Merge branch 'for-linus' of git://oss.sgi.com:8090/xfs/xfs-2.6
[linux-2.6] / fs / ext4 / inode.c
1 /*
2  *  linux/fs/ext4/inode.c
3  *
4  * Copyright (C) 1992, 1993, 1994, 1995
5  * Remy Card (card@masi.ibp.fr)
6  * Laboratoire MASI - Institut Blaise Pascal
7  * Universite Pierre et Marie Curie (Paris VI)
8  *
9  *  from
10  *
11  *  linux/fs/minix/inode.c
12  *
13  *  Copyright (C) 1991, 1992  Linus Torvalds
14  *
15  *  Goal-directed block allocation by Stephen Tweedie
16  *      (sct@redhat.com), 1993, 1998
17  *  Big-endian to little-endian byte-swapping/bitmaps by
18  *        David S. Miller (davem@caip.rutgers.edu), 1995
19  *  64-bit file support on 64-bit platforms by Jakub Jelinek
20  *      (jj@sunsite.ms.mff.cuni.cz)
21  *
22  *  Assorted race fixes, rewrite of ext4_get_block() by Al Viro, 2000
23  */
24
25 #include <linux/module.h>
26 #include <linux/fs.h>
27 #include <linux/time.h>
28 #include <linux/ext4_jbd2.h>
29 #include <linux/jbd2.h>
30 #include <linux/highuid.h>
31 #include <linux/pagemap.h>
32 #include <linux/quotaops.h>
33 #include <linux/string.h>
34 #include <linux/buffer_head.h>
35 #include <linux/writeback.h>
36 #include <linux/mpage.h>
37 #include <linux/uio.h>
38 #include <linux/bio.h>
39 #include "xattr.h"
40 #include "acl.h"
41
42 /*
43  * Test whether an inode is a fast symlink.
44  */
45 static int ext4_inode_is_fast_symlink(struct inode *inode)
46 {
47         int ea_blocks = EXT4_I(inode)->i_file_acl ?
48                 (inode->i_sb->s_blocksize >> 9) : 0;
49
50         return (S_ISLNK(inode->i_mode) && inode->i_blocks - ea_blocks == 0);
51 }
52
53 /*
54  * The ext4 forget function must perform a revoke if we are freeing data
55  * which has been journaled.  Metadata (eg. indirect blocks) must be
56  * revoked in all cases.
57  *
58  * "bh" may be NULL: a metadata block may have been freed from memory
59  * but there may still be a record of it in the journal, and that record
60  * still needs to be revoked.
61  */
62 int ext4_forget(handle_t *handle, int is_metadata, struct inode *inode,
63                         struct buffer_head *bh, ext4_fsblk_t blocknr)
64 {
65         int err;
66
67         might_sleep();
68
69         BUFFER_TRACE(bh, "enter");
70
71         jbd_debug(4, "forgetting bh %p: is_metadata = %d, mode %o, "
72                   "data mode %lx\n",
73                   bh, is_metadata, inode->i_mode,
74                   test_opt(inode->i_sb, DATA_FLAGS));
75
76         /* Never use the revoke function if we are doing full data
77          * journaling: there is no need to, and a V1 superblock won't
78          * support it.  Otherwise, only skip the revoke on un-journaled
79          * data blocks. */
80
81         if (test_opt(inode->i_sb, DATA_FLAGS) == EXT4_MOUNT_JOURNAL_DATA ||
82             (!is_metadata && !ext4_should_journal_data(inode))) {
83                 if (bh) {
84                         BUFFER_TRACE(bh, "call jbd2_journal_forget");
85                         return ext4_journal_forget(handle, bh);
86                 }
87                 return 0;
88         }
89
90         /*
91          * data!=journal && (is_metadata || should_journal_data(inode))
92          */
93         BUFFER_TRACE(bh, "call ext4_journal_revoke");
94         err = ext4_journal_revoke(handle, blocknr, bh);
95         if (err)
96                 ext4_abort(inode->i_sb, __FUNCTION__,
97                            "error %d when attempting revoke", err);
98         BUFFER_TRACE(bh, "exit");
99         return err;
100 }
101
102 /*
103  * Work out how many blocks we need to proceed with the next chunk of a
104  * truncate transaction.
105  */
106 static unsigned long blocks_for_truncate(struct inode *inode)
107 {
108         ext4_lblk_t needed;
109
110         needed = inode->i_blocks >> (inode->i_sb->s_blocksize_bits - 9);
111
112         /* Give ourselves just enough room to cope with inodes in which
113          * i_blocks is corrupt: we've seen disk corruptions in the past
114          * which resulted in random data in an inode which looked enough
115          * like a regular file for ext4 to try to delete it.  Things
116          * will go a bit crazy if that happens, but at least we should
117          * try not to panic the whole kernel. */
118         if (needed < 2)
119                 needed = 2;
120
121         /* But we need to bound the transaction so we don't overflow the
122          * journal. */
123         if (needed > EXT4_MAX_TRANS_DATA)
124                 needed = EXT4_MAX_TRANS_DATA;
125
126         return EXT4_DATA_TRANS_BLOCKS(inode->i_sb) + needed;
127 }
128
129 /*
130  * Truncate transactions can be complex and absolutely huge.  So we need to
131  * be able to restart the transaction at a conventient checkpoint to make
132  * sure we don't overflow the journal.
133  *
134  * start_transaction gets us a new handle for a truncate transaction,
135  * and extend_transaction tries to extend the existing one a bit.  If
136  * extend fails, we need to propagate the failure up and restart the
137  * transaction in the top-level truncate loop. --sct
138  */
139 static handle_t *start_transaction(struct inode *inode)
140 {
141         handle_t *result;
142
143         result = ext4_journal_start(inode, blocks_for_truncate(inode));
144         if (!IS_ERR(result))
145                 return result;
146
147         ext4_std_error(inode->i_sb, PTR_ERR(result));
148         return result;
149 }
150
151 /*
152  * Try to extend this transaction for the purposes of truncation.
153  *
154  * Returns 0 if we managed to create more room.  If we can't create more
155  * room, and the transaction must be restarted we return 1.
156  */
157 static int try_to_extend_transaction(handle_t *handle, struct inode *inode)
158 {
159         if (handle->h_buffer_credits > EXT4_RESERVE_TRANS_BLOCKS)
160                 return 0;
161         if (!ext4_journal_extend(handle, blocks_for_truncate(inode)))
162                 return 0;
163         return 1;
164 }
165
166 /*
167  * Restart the transaction associated with *handle.  This does a commit,
168  * so before we call here everything must be consistently dirtied against
169  * this transaction.
170  */
171 static int ext4_journal_test_restart(handle_t *handle, struct inode *inode)
172 {
173         jbd_debug(2, "restarting handle %p\n", handle);
174         return ext4_journal_restart(handle, blocks_for_truncate(inode));
175 }
176
177 /*
178  * Called at the last iput() if i_nlink is zero.
179  */
180 void ext4_delete_inode (struct inode * inode)
181 {
182         handle_t *handle;
183
184         truncate_inode_pages(&inode->i_data, 0);
185
186         if (is_bad_inode(inode))
187                 goto no_delete;
188
189         handle = start_transaction(inode);
190         if (IS_ERR(handle)) {
191                 /*
192                  * If we're going to skip the normal cleanup, we still need to
193                  * make sure that the in-core orphan linked list is properly
194                  * cleaned up.
195                  */
196                 ext4_orphan_del(NULL, inode);
197                 goto no_delete;
198         }
199
200         if (IS_SYNC(inode))
201                 handle->h_sync = 1;
202         inode->i_size = 0;
203         if (inode->i_blocks)
204                 ext4_truncate(inode);
205         /*
206          * Kill off the orphan record which ext4_truncate created.
207          * AKPM: I think this can be inside the above `if'.
208          * Note that ext4_orphan_del() has to be able to cope with the
209          * deletion of a non-existent orphan - this is because we don't
210          * know if ext4_truncate() actually created an orphan record.
211          * (Well, we could do this if we need to, but heck - it works)
212          */
213         ext4_orphan_del(handle, inode);
214         EXT4_I(inode)->i_dtime  = get_seconds();
215
216         /*
217          * One subtle ordering requirement: if anything has gone wrong
218          * (transaction abort, IO errors, whatever), then we can still
219          * do these next steps (the fs will already have been marked as
220          * having errors), but we can't free the inode if the mark_dirty
221          * fails.
222          */
223         if (ext4_mark_inode_dirty(handle, inode))
224                 /* If that failed, just do the required in-core inode clear. */
225                 clear_inode(inode);
226         else
227                 ext4_free_inode(handle, inode);
228         ext4_journal_stop(handle);
229         return;
230 no_delete:
231         clear_inode(inode);     /* We must guarantee clearing of inode... */
232 }
233
234 typedef struct {
235         __le32  *p;
236         __le32  key;
237         struct buffer_head *bh;
238 } Indirect;
239
240 static inline void add_chain(Indirect *p, struct buffer_head *bh, __le32 *v)
241 {
242         p->key = *(p->p = v);
243         p->bh = bh;
244 }
245
246 /**
247  *      ext4_block_to_path - parse the block number into array of offsets
248  *      @inode: inode in question (we are only interested in its superblock)
249  *      @i_block: block number to be parsed
250  *      @offsets: array to store the offsets in
251  *      @boundary: set this non-zero if the referred-to block is likely to be
252  *             followed (on disk) by an indirect block.
253  *
254  *      To store the locations of file's data ext4 uses a data structure common
255  *      for UNIX filesystems - tree of pointers anchored in the inode, with
256  *      data blocks at leaves and indirect blocks in intermediate nodes.
257  *      This function translates the block number into path in that tree -
258  *      return value is the path length and @offsets[n] is the offset of
259  *      pointer to (n+1)th node in the nth one. If @block is out of range
260  *      (negative or too large) warning is printed and zero returned.
261  *
262  *      Note: function doesn't find node addresses, so no IO is needed. All
263  *      we need to know is the capacity of indirect blocks (taken from the
264  *      inode->i_sb).
265  */
266
267 /*
268  * Portability note: the last comparison (check that we fit into triple
269  * indirect block) is spelled differently, because otherwise on an
270  * architecture with 32-bit longs and 8Kb pages we might get into trouble
271  * if our filesystem had 8Kb blocks. We might use long long, but that would
272  * kill us on x86. Oh, well, at least the sign propagation does not matter -
273  * i_block would have to be negative in the very beginning, so we would not
274  * get there at all.
275  */
276
277 static int ext4_block_to_path(struct inode *inode,
278                         ext4_lblk_t i_block,
279                         ext4_lblk_t offsets[4], int *boundary)
280 {
281         int ptrs = EXT4_ADDR_PER_BLOCK(inode->i_sb);
282         int ptrs_bits = EXT4_ADDR_PER_BLOCK_BITS(inode->i_sb);
283         const long direct_blocks = EXT4_NDIR_BLOCKS,
284                 indirect_blocks = ptrs,
285                 double_blocks = (1 << (ptrs_bits * 2));
286         int n = 0;
287         int final = 0;
288
289         if (i_block < 0) {
290                 ext4_warning (inode->i_sb, "ext4_block_to_path", "block < 0");
291         } else if (i_block < direct_blocks) {
292                 offsets[n++] = i_block;
293                 final = direct_blocks;
294         } else if ( (i_block -= direct_blocks) < indirect_blocks) {
295                 offsets[n++] = EXT4_IND_BLOCK;
296                 offsets[n++] = i_block;
297                 final = ptrs;
298         } else if ((i_block -= indirect_blocks) < double_blocks) {
299                 offsets[n++] = EXT4_DIND_BLOCK;
300                 offsets[n++] = i_block >> ptrs_bits;
301                 offsets[n++] = i_block & (ptrs - 1);
302                 final = ptrs;
303         } else if (((i_block -= double_blocks) >> (ptrs_bits * 2)) < ptrs) {
304                 offsets[n++] = EXT4_TIND_BLOCK;
305                 offsets[n++] = i_block >> (ptrs_bits * 2);
306                 offsets[n++] = (i_block >> ptrs_bits) & (ptrs - 1);
307                 offsets[n++] = i_block & (ptrs - 1);
308                 final = ptrs;
309         } else {
310                 ext4_warning(inode->i_sb, "ext4_block_to_path",
311                                 "block %lu > max",
312                                 i_block + direct_blocks +
313                                 indirect_blocks + double_blocks);
314         }
315         if (boundary)
316                 *boundary = final - 1 - (i_block & (ptrs - 1));
317         return n;
318 }
319
320 /**
321  *      ext4_get_branch - read the chain of indirect blocks leading to data
322  *      @inode: inode in question
323  *      @depth: depth of the chain (1 - direct pointer, etc.)
324  *      @offsets: offsets of pointers in inode/indirect blocks
325  *      @chain: place to store the result
326  *      @err: here we store the error value
327  *
328  *      Function fills the array of triples <key, p, bh> and returns %NULL
329  *      if everything went OK or the pointer to the last filled triple
330  *      (incomplete one) otherwise. Upon the return chain[i].key contains
331  *      the number of (i+1)-th block in the chain (as it is stored in memory,
332  *      i.e. little-endian 32-bit), chain[i].p contains the address of that
333  *      number (it points into struct inode for i==0 and into the bh->b_data
334  *      for i>0) and chain[i].bh points to the buffer_head of i-th indirect
335  *      block for i>0 and NULL for i==0. In other words, it holds the block
336  *      numbers of the chain, addresses they were taken from (and where we can
337  *      verify that chain did not change) and buffer_heads hosting these
338  *      numbers.
339  *
340  *      Function stops when it stumbles upon zero pointer (absent block)
341  *              (pointer to last triple returned, *@err == 0)
342  *      or when it gets an IO error reading an indirect block
343  *              (ditto, *@err == -EIO)
344  *      or when it reads all @depth-1 indirect blocks successfully and finds
345  *      the whole chain, all way to the data (returns %NULL, *err == 0).
346  *
347  *      Need to be called with
348  *      down_read(&EXT4_I(inode)->i_data_sem)
349  */
350 static Indirect *ext4_get_branch(struct inode *inode, int depth,
351                                  ext4_lblk_t  *offsets,
352                                  Indirect chain[4], int *err)
353 {
354         struct super_block *sb = inode->i_sb;
355         Indirect *p = chain;
356         struct buffer_head *bh;
357
358         *err = 0;
359         /* i_data is not going away, no lock needed */
360         add_chain (chain, NULL, EXT4_I(inode)->i_data + *offsets);
361         if (!p->key)
362                 goto no_block;
363         while (--depth) {
364                 bh = sb_bread(sb, le32_to_cpu(p->key));
365                 if (!bh)
366                         goto failure;
367                 add_chain(++p, bh, (__le32*)bh->b_data + *++offsets);
368                 /* Reader: end */
369                 if (!p->key)
370                         goto no_block;
371         }
372         return NULL;
373
374 failure:
375         *err = -EIO;
376 no_block:
377         return p;
378 }
379
380 /**
381  *      ext4_find_near - find a place for allocation with sufficient locality
382  *      @inode: owner
383  *      @ind: descriptor of indirect block.
384  *
385  *      This function returns the prefered place for block allocation.
386  *      It is used when heuristic for sequential allocation fails.
387  *      Rules are:
388  *        + if there is a block to the left of our position - allocate near it.
389  *        + if pointer will live in indirect block - allocate near that block.
390  *        + if pointer will live in inode - allocate in the same
391  *          cylinder group.
392  *
393  * In the latter case we colour the starting block by the callers PID to
394  * prevent it from clashing with concurrent allocations for a different inode
395  * in the same block group.   The PID is used here so that functionally related
396  * files will be close-by on-disk.
397  *
398  *      Caller must make sure that @ind is valid and will stay that way.
399  */
400 static ext4_fsblk_t ext4_find_near(struct inode *inode, Indirect *ind)
401 {
402         struct ext4_inode_info *ei = EXT4_I(inode);
403         __le32 *start = ind->bh ? (__le32*) ind->bh->b_data : ei->i_data;
404         __le32 *p;
405         ext4_fsblk_t bg_start;
406         ext4_fsblk_t last_block;
407         ext4_grpblk_t colour;
408
409         /* Try to find previous block */
410         for (p = ind->p - 1; p >= start; p--) {
411                 if (*p)
412                         return le32_to_cpu(*p);
413         }
414
415         /* No such thing, so let's try location of indirect block */
416         if (ind->bh)
417                 return ind->bh->b_blocknr;
418
419         /*
420          * It is going to be referred to from the inode itself? OK, just put it
421          * into the same cylinder group then.
422          */
423         bg_start = ext4_group_first_block_no(inode->i_sb, ei->i_block_group);
424         last_block = ext4_blocks_count(EXT4_SB(inode->i_sb)->s_es) - 1;
425
426         if (bg_start + EXT4_BLOCKS_PER_GROUP(inode->i_sb) <= last_block)
427                 colour = (current->pid % 16) *
428                         (EXT4_BLOCKS_PER_GROUP(inode->i_sb) / 16);
429         else
430                 colour = (current->pid % 16) * ((last_block - bg_start) / 16);
431         return bg_start + colour;
432 }
433
434 /**
435  *      ext4_find_goal - find a prefered place for allocation.
436  *      @inode: owner
437  *      @block:  block we want
438  *      @partial: pointer to the last triple within a chain
439  *
440  *      Normally this function find the prefered place for block allocation,
441  *      returns it.
442  */
443 static ext4_fsblk_t ext4_find_goal(struct inode *inode, ext4_lblk_t block,
444                 Indirect *partial)
445 {
446         struct ext4_block_alloc_info *block_i;
447
448         block_i =  EXT4_I(inode)->i_block_alloc_info;
449
450         /*
451          * try the heuristic for sequential allocation,
452          * failing that at least try to get decent locality.
453          */
454         if (block_i && (block == block_i->last_alloc_logical_block + 1)
455                 && (block_i->last_alloc_physical_block != 0)) {
456                 return block_i->last_alloc_physical_block + 1;
457         }
458
459         return ext4_find_near(inode, partial);
460 }
461
462 /**
463  *      ext4_blks_to_allocate: Look up the block map and count the number
464  *      of direct blocks need to be allocated for the given branch.
465  *
466  *      @branch: chain of indirect blocks
467  *      @k: number of blocks need for indirect blocks
468  *      @blks: number of data blocks to be mapped.
469  *      @blocks_to_boundary:  the offset in the indirect block
470  *
471  *      return the total number of blocks to be allocate, including the
472  *      direct and indirect blocks.
473  */
474 static int ext4_blks_to_allocate(Indirect *branch, int k, unsigned long blks,
475                 int blocks_to_boundary)
476 {
477         unsigned long count = 0;
478
479         /*
480          * Simple case, [t,d]Indirect block(s) has not allocated yet
481          * then it's clear blocks on that path have not allocated
482          */
483         if (k > 0) {
484                 /* right now we don't handle cross boundary allocation */
485                 if (blks < blocks_to_boundary + 1)
486                         count += blks;
487                 else
488                         count += blocks_to_boundary + 1;
489                 return count;
490         }
491
492         count++;
493         while (count < blks && count <= blocks_to_boundary &&
494                 le32_to_cpu(*(branch[0].p + count)) == 0) {
495                 count++;
496         }
497         return count;
498 }
499
500 /**
501  *      ext4_alloc_blocks: multiple allocate blocks needed for a branch
502  *      @indirect_blks: the number of blocks need to allocate for indirect
503  *                      blocks
504  *
505  *      @new_blocks: on return it will store the new block numbers for
506  *      the indirect blocks(if needed) and the first direct block,
507  *      @blks:  on return it will store the total number of allocated
508  *              direct blocks
509  */
510 static int ext4_alloc_blocks(handle_t *handle, struct inode *inode,
511                         ext4_fsblk_t goal, int indirect_blks, int blks,
512                         ext4_fsblk_t new_blocks[4], int *err)
513 {
514         int target, i;
515         unsigned long count = 0;
516         int index = 0;
517         ext4_fsblk_t current_block = 0;
518         int ret = 0;
519
520         /*
521          * Here we try to allocate the requested multiple blocks at once,
522          * on a best-effort basis.
523          * To build a branch, we should allocate blocks for
524          * the indirect blocks(if not allocated yet), and at least
525          * the first direct block of this branch.  That's the
526          * minimum number of blocks need to allocate(required)
527          */
528         target = blks + indirect_blks;
529
530         while (1) {
531                 count = target;
532                 /* allocating blocks for indirect blocks and direct blocks */
533                 current_block = ext4_new_blocks(handle,inode,goal,&count,err);
534                 if (*err)
535                         goto failed_out;
536
537                 target -= count;
538                 /* allocate blocks for indirect blocks */
539                 while (index < indirect_blks && count) {
540                         new_blocks[index++] = current_block++;
541                         count--;
542                 }
543
544                 if (count > 0)
545                         break;
546         }
547
548         /* save the new block number for the first direct block */
549         new_blocks[index] = current_block;
550
551         /* total number of blocks allocated for direct blocks */
552         ret = count;
553         *err = 0;
554         return ret;
555 failed_out:
556         for (i = 0; i <index; i++)
557                 ext4_free_blocks(handle, inode, new_blocks[i], 1, 0);
558         return ret;
559 }
560
561 /**
562  *      ext4_alloc_branch - allocate and set up a chain of blocks.
563  *      @inode: owner
564  *      @indirect_blks: number of allocated indirect blocks
565  *      @blks: number of allocated direct blocks
566  *      @offsets: offsets (in the blocks) to store the pointers to next.
567  *      @branch: place to store the chain in.
568  *
569  *      This function allocates blocks, zeroes out all but the last one,
570  *      links them into chain and (if we are synchronous) writes them to disk.
571  *      In other words, it prepares a branch that can be spliced onto the
572  *      inode. It stores the information about that chain in the branch[], in
573  *      the same format as ext4_get_branch() would do. We are calling it after
574  *      we had read the existing part of chain and partial points to the last
575  *      triple of that (one with zero ->key). Upon the exit we have the same
576  *      picture as after the successful ext4_get_block(), except that in one
577  *      place chain is disconnected - *branch->p is still zero (we did not
578  *      set the last link), but branch->key contains the number that should
579  *      be placed into *branch->p to fill that gap.
580  *
581  *      If allocation fails we free all blocks we've allocated (and forget
582  *      their buffer_heads) and return the error value the from failed
583  *      ext4_alloc_block() (normally -ENOSPC). Otherwise we set the chain
584  *      as described above and return 0.
585  */
586 static int ext4_alloc_branch(handle_t *handle, struct inode *inode,
587                         int indirect_blks, int *blks, ext4_fsblk_t goal,
588                         ext4_lblk_t *offsets, Indirect *branch)
589 {
590         int blocksize = inode->i_sb->s_blocksize;
591         int i, n = 0;
592         int err = 0;
593         struct buffer_head *bh;
594         int num;
595         ext4_fsblk_t new_blocks[4];
596         ext4_fsblk_t current_block;
597
598         num = ext4_alloc_blocks(handle, inode, goal, indirect_blks,
599                                 *blks, new_blocks, &err);
600         if (err)
601                 return err;
602
603         branch[0].key = cpu_to_le32(new_blocks[0]);
604         /*
605          * metadata blocks and data blocks are allocated.
606          */
607         for (n = 1; n <= indirect_blks;  n++) {
608                 /*
609                  * Get buffer_head for parent block, zero it out
610                  * and set the pointer to new one, then send
611                  * parent to disk.
612                  */
613                 bh = sb_getblk(inode->i_sb, new_blocks[n-1]);
614                 branch[n].bh = bh;
615                 lock_buffer(bh);
616                 BUFFER_TRACE(bh, "call get_create_access");
617                 err = ext4_journal_get_create_access(handle, bh);
618                 if (err) {
619                         unlock_buffer(bh);
620                         brelse(bh);
621                         goto failed;
622                 }
623
624                 memset(bh->b_data, 0, blocksize);
625                 branch[n].p = (__le32 *) bh->b_data + offsets[n];
626                 branch[n].key = cpu_to_le32(new_blocks[n]);
627                 *branch[n].p = branch[n].key;
628                 if ( n == indirect_blks) {
629                         current_block = new_blocks[n];
630                         /*
631                          * End of chain, update the last new metablock of
632                          * the chain to point to the new allocated
633                          * data blocks numbers
634                          */
635                         for (i=1; i < num; i++)
636                                 *(branch[n].p + i) = cpu_to_le32(++current_block);
637                 }
638                 BUFFER_TRACE(bh, "marking uptodate");
639                 set_buffer_uptodate(bh);
640                 unlock_buffer(bh);
641
642                 BUFFER_TRACE(bh, "call ext4_journal_dirty_metadata");
643                 err = ext4_journal_dirty_metadata(handle, bh);
644                 if (err)
645                         goto failed;
646         }
647         *blks = num;
648         return err;
649 failed:
650         /* Allocation failed, free what we already allocated */
651         for (i = 1; i <= n ; i++) {
652                 BUFFER_TRACE(branch[i].bh, "call jbd2_journal_forget");
653                 ext4_journal_forget(handle, branch[i].bh);
654         }
655         for (i = 0; i <indirect_blks; i++)
656                 ext4_free_blocks(handle, inode, new_blocks[i], 1, 0);
657
658         ext4_free_blocks(handle, inode, new_blocks[i], num, 0);
659
660         return err;
661 }
662
663 /**
664  * ext4_splice_branch - splice the allocated branch onto inode.
665  * @inode: owner
666  * @block: (logical) number of block we are adding
667  * @chain: chain of indirect blocks (with a missing link - see
668  *      ext4_alloc_branch)
669  * @where: location of missing link
670  * @num:   number of indirect blocks we are adding
671  * @blks:  number of direct blocks we are adding
672  *
673  * This function fills the missing link and does all housekeeping needed in
674  * inode (->i_blocks, etc.). In case of success we end up with the full
675  * chain to new block and return 0.
676  */
677 static int ext4_splice_branch(handle_t *handle, struct inode *inode,
678                         ext4_lblk_t block, Indirect *where, int num, int blks)
679 {
680         int i;
681         int err = 0;
682         struct ext4_block_alloc_info *block_i;
683         ext4_fsblk_t current_block;
684
685         block_i = EXT4_I(inode)->i_block_alloc_info;
686         /*
687          * If we're splicing into a [td]indirect block (as opposed to the
688          * inode) then we need to get write access to the [td]indirect block
689          * before the splice.
690          */
691         if (where->bh) {
692                 BUFFER_TRACE(where->bh, "get_write_access");
693                 err = ext4_journal_get_write_access(handle, where->bh);
694                 if (err)
695                         goto err_out;
696         }
697         /* That's it */
698
699         *where->p = where->key;
700
701         /*
702          * Update the host buffer_head or inode to point to more just allocated
703          * direct blocks blocks
704          */
705         if (num == 0 && blks > 1) {
706                 current_block = le32_to_cpu(where->key) + 1;
707                 for (i = 1; i < blks; i++)
708                         *(where->p + i ) = cpu_to_le32(current_block++);
709         }
710
711         /*
712          * update the most recently allocated logical & physical block
713          * in i_block_alloc_info, to assist find the proper goal block for next
714          * allocation
715          */
716         if (block_i) {
717                 block_i->last_alloc_logical_block = block + blks - 1;
718                 block_i->last_alloc_physical_block =
719                                 le32_to_cpu(where[num].key) + blks - 1;
720         }
721
722         /* We are done with atomic stuff, now do the rest of housekeeping */
723
724         inode->i_ctime = ext4_current_time(inode);
725         ext4_mark_inode_dirty(handle, inode);
726
727         /* had we spliced it onto indirect block? */
728         if (where->bh) {
729                 /*
730                  * If we spliced it onto an indirect block, we haven't
731                  * altered the inode.  Note however that if it is being spliced
732                  * onto an indirect block at the very end of the file (the
733                  * file is growing) then we *will* alter the inode to reflect
734                  * the new i_size.  But that is not done here - it is done in
735                  * generic_commit_write->__mark_inode_dirty->ext4_dirty_inode.
736                  */
737                 jbd_debug(5, "splicing indirect only\n");
738                 BUFFER_TRACE(where->bh, "call ext4_journal_dirty_metadata");
739                 err = ext4_journal_dirty_metadata(handle, where->bh);
740                 if (err)
741                         goto err_out;
742         } else {
743                 /*
744                  * OK, we spliced it into the inode itself on a direct block.
745                  * Inode was dirtied above.
746                  */
747                 jbd_debug(5, "splicing direct\n");
748         }
749         return err;
750
751 err_out:
752         for (i = 1; i <= num; i++) {
753                 BUFFER_TRACE(where[i].bh, "call jbd2_journal_forget");
754                 ext4_journal_forget(handle, where[i].bh);
755                 ext4_free_blocks(handle, inode,
756                                         le32_to_cpu(where[i-1].key), 1, 0);
757         }
758         ext4_free_blocks(handle, inode, le32_to_cpu(where[num].key), blks, 0);
759
760         return err;
761 }
762
763 /*
764  * Allocation strategy is simple: if we have to allocate something, we will
765  * have to go the whole way to leaf. So let's do it before attaching anything
766  * to tree, set linkage between the newborn blocks, write them if sync is
767  * required, recheck the path, free and repeat if check fails, otherwise
768  * set the last missing link (that will protect us from any truncate-generated
769  * removals - all blocks on the path are immune now) and possibly force the
770  * write on the parent block.
771  * That has a nice additional property: no special recovery from the failed
772  * allocations is needed - we simply release blocks and do not touch anything
773  * reachable from inode.
774  *
775  * `handle' can be NULL if create == 0.
776  *
777  * return > 0, # of blocks mapped or allocated.
778  * return = 0, if plain lookup failed.
779  * return < 0, error case.
780  *
781  *
782  * Need to be called with
783  * down_read(&EXT4_I(inode)->i_data_sem) if not allocating file system block
784  * (ie, create is zero). Otherwise down_write(&EXT4_I(inode)->i_data_sem)
785  */
786 int ext4_get_blocks_handle(handle_t *handle, struct inode *inode,
787                 ext4_lblk_t iblock, unsigned long maxblocks,
788                 struct buffer_head *bh_result,
789                 int create, int extend_disksize)
790 {
791         int err = -EIO;
792         ext4_lblk_t offsets[4];
793         Indirect chain[4];
794         Indirect *partial;
795         ext4_fsblk_t goal;
796         int indirect_blks;
797         int blocks_to_boundary = 0;
798         int depth;
799         struct ext4_inode_info *ei = EXT4_I(inode);
800         int count = 0;
801         ext4_fsblk_t first_block = 0;
802
803
804         J_ASSERT(!(EXT4_I(inode)->i_flags & EXT4_EXTENTS_FL));
805         J_ASSERT(handle != NULL || create == 0);
806         depth = ext4_block_to_path(inode, iblock, offsets,
807                                         &blocks_to_boundary);
808
809         if (depth == 0)
810                 goto out;
811
812         partial = ext4_get_branch(inode, depth, offsets, chain, &err);
813
814         /* Simplest case - block found, no allocation needed */
815         if (!partial) {
816                 first_block = le32_to_cpu(chain[depth - 1].key);
817                 clear_buffer_new(bh_result);
818                 count++;
819                 /*map more blocks*/
820                 while (count < maxblocks && count <= blocks_to_boundary) {
821                         ext4_fsblk_t blk;
822
823                         blk = le32_to_cpu(*(chain[depth-1].p + count));
824
825                         if (blk == first_block + count)
826                                 count++;
827                         else
828                                 break;
829                 }
830                 goto got_it;
831         }
832
833         /* Next simple case - plain lookup or failed read of indirect block */
834         if (!create || err == -EIO)
835                 goto cleanup;
836
837         /*
838          * Okay, we need to do block allocation.  Lazily initialize the block
839          * allocation info here if necessary
840         */
841         if (S_ISREG(inode->i_mode) && (!ei->i_block_alloc_info))
842                 ext4_init_block_alloc_info(inode);
843
844         goal = ext4_find_goal(inode, iblock, partial);
845
846         /* the number of blocks need to allocate for [d,t]indirect blocks */
847         indirect_blks = (chain + depth) - partial - 1;
848
849         /*
850          * Next look up the indirect map to count the totoal number of
851          * direct blocks to allocate for this branch.
852          */
853         count = ext4_blks_to_allocate(partial, indirect_blks,
854                                         maxblocks, blocks_to_boundary);
855         /*
856          * Block out ext4_truncate while we alter the tree
857          */
858         err = ext4_alloc_branch(handle, inode, indirect_blks, &count, goal,
859                                 offsets + (partial - chain), partial);
860
861         /*
862          * The ext4_splice_branch call will free and forget any buffers
863          * on the new chain if there is a failure, but that risks using
864          * up transaction credits, especially for bitmaps where the
865          * credits cannot be returned.  Can we handle this somehow?  We
866          * may need to return -EAGAIN upwards in the worst case.  --sct
867          */
868         if (!err)
869                 err = ext4_splice_branch(handle, inode, iblock,
870                                         partial, indirect_blks, count);
871         /*
872          * i_disksize growing is protected by i_data_sem.  Don't forget to
873          * protect it if you're about to implement concurrent
874          * ext4_get_block() -bzzz
875         */
876         if (!err && extend_disksize && inode->i_size > ei->i_disksize)
877                 ei->i_disksize = inode->i_size;
878         if (err)
879                 goto cleanup;
880
881         set_buffer_new(bh_result);
882 got_it:
883         map_bh(bh_result, inode->i_sb, le32_to_cpu(chain[depth-1].key));
884         if (count > blocks_to_boundary)
885                 set_buffer_boundary(bh_result);
886         err = count;
887         /* Clean up and exit */
888         partial = chain + depth - 1;    /* the whole chain */
889 cleanup:
890         while (partial > chain) {
891                 BUFFER_TRACE(partial->bh, "call brelse");
892                 brelse(partial->bh);
893                 partial--;
894         }
895         BUFFER_TRACE(bh_result, "returned");
896 out:
897         return err;
898 }
899
900 /* Maximum number of blocks we map for direct IO at once. */
901 #define DIO_MAX_BLOCKS 4096
902 /*
903  * Number of credits we need for writing DIO_MAX_BLOCKS:
904  * We need sb + group descriptor + bitmap + inode -> 4
905  * For B blocks with A block pointers per block we need:
906  * 1 (triple ind.) + (B/A/A + 2) (doubly ind.) + (B/A + 2) (indirect).
907  * If we plug in 4096 for B and 256 for A (for 1KB block size), we get 25.
908  */
909 #define DIO_CREDITS 25
910
911
912 /*
913  *
914  *
915  * ext4_ext4 get_block() wrapper function
916  * It will do a look up first, and returns if the blocks already mapped.
917  * Otherwise it takes the write lock of the i_data_sem and allocate blocks
918  * and store the allocated blocks in the result buffer head and mark it
919  * mapped.
920  *
921  * If file type is extents based, it will call ext4_ext_get_blocks(),
922  * Otherwise, call with ext4_get_blocks_handle() to handle indirect mapping
923  * based files
924  *
925  * On success, it returns the number of blocks being mapped or allocate.
926  * if create==0 and the blocks are pre-allocated and uninitialized block,
927  * the result buffer head is unmapped. If the create ==1, it will make sure
928  * the buffer head is mapped.
929  *
930  * It returns 0 if plain look up failed (blocks have not been allocated), in
931  * that casem, buffer head is unmapped
932  *
933  * It returns the error in case of allocation failure.
934  */
935 int ext4_get_blocks_wrap(handle_t *handle, struct inode *inode, sector_t block,
936                         unsigned long max_blocks, struct buffer_head *bh,
937                         int create, int extend_disksize)
938 {
939         int retval;
940
941         clear_buffer_mapped(bh);
942
943         /*
944          * Try to see if we can get  the block without requesting
945          * for new file system block.
946          */
947         down_read((&EXT4_I(inode)->i_data_sem));
948         if (EXT4_I(inode)->i_flags & EXT4_EXTENTS_FL) {
949                 retval =  ext4_ext_get_blocks(handle, inode, block, max_blocks,
950                                 bh, 0, 0);
951         } else {
952                 retval = ext4_get_blocks_handle(handle,
953                                 inode, block, max_blocks, bh, 0, 0);
954         }
955         up_read((&EXT4_I(inode)->i_data_sem));
956
957         /* If it is only a block(s) look up */
958         if (!create)
959                 return retval;
960
961         /*
962          * Returns if the blocks have already allocated
963          *
964          * Note that if blocks have been preallocated
965          * ext4_ext_get_block() returns th create = 0
966          * with buffer head unmapped.
967          */
968         if (retval > 0 && buffer_mapped(bh))
969                 return retval;
970
971         /*
972          * New blocks allocate and/or writing to uninitialized extent
973          * will possibly result in updating i_data, so we take
974          * the write lock of i_data_sem, and call get_blocks()
975          * with create == 1 flag.
976          */
977         down_write((&EXT4_I(inode)->i_data_sem));
978         /*
979          * We need to check for EXT4 here because migrate
980          * could have changed the inode type in between
981          */
982         if (EXT4_I(inode)->i_flags & EXT4_EXTENTS_FL) {
983                 retval =  ext4_ext_get_blocks(handle, inode, block, max_blocks,
984                                 bh, create, extend_disksize);
985         } else {
986                 retval = ext4_get_blocks_handle(handle, inode, block,
987                                 max_blocks, bh, create, extend_disksize);
988         }
989         up_write((&EXT4_I(inode)->i_data_sem));
990         return retval;
991 }
992
993 static int ext4_get_block(struct inode *inode, sector_t iblock,
994                         struct buffer_head *bh_result, int create)
995 {
996         handle_t *handle = ext4_journal_current_handle();
997         int ret = 0, started = 0;
998         unsigned max_blocks = bh_result->b_size >> inode->i_blkbits;
999
1000         if (create && !handle) {
1001                 /* Direct IO write... */
1002                 if (max_blocks > DIO_MAX_BLOCKS)
1003                         max_blocks = DIO_MAX_BLOCKS;
1004                 handle = ext4_journal_start(inode, DIO_CREDITS +
1005                               2 * EXT4_QUOTA_TRANS_BLOCKS(inode->i_sb));
1006                 if (IS_ERR(handle)) {
1007                         ret = PTR_ERR(handle);
1008                         goto out;
1009                 }
1010                 started = 1;
1011         }
1012
1013         ret = ext4_get_blocks_wrap(handle, inode, iblock,
1014                                         max_blocks, bh_result, create, 0);
1015         if (ret > 0) {
1016                 bh_result->b_size = (ret << inode->i_blkbits);
1017                 ret = 0;
1018         }
1019         if (started)
1020                 ext4_journal_stop(handle);
1021 out:
1022         return ret;
1023 }
1024
1025 /*
1026  * `handle' can be NULL if create is zero
1027  */
1028 struct buffer_head *ext4_getblk(handle_t *handle, struct inode *inode,
1029                                 ext4_lblk_t block, int create, int *errp)
1030 {
1031         struct buffer_head dummy;
1032         int fatal = 0, err;
1033
1034         J_ASSERT(handle != NULL || create == 0);
1035
1036         dummy.b_state = 0;
1037         dummy.b_blocknr = -1000;
1038         buffer_trace_init(&dummy.b_history);
1039         err = ext4_get_blocks_wrap(handle, inode, block, 1,
1040                                         &dummy, create, 1);
1041         /*
1042          * ext4_get_blocks_handle() returns number of blocks
1043          * mapped. 0 in case of a HOLE.
1044          */
1045         if (err > 0) {
1046                 if (err > 1)
1047                         WARN_ON(1);
1048                 err = 0;
1049         }
1050         *errp = err;
1051         if (!err && buffer_mapped(&dummy)) {
1052                 struct buffer_head *bh;
1053                 bh = sb_getblk(inode->i_sb, dummy.b_blocknr);
1054                 if (!bh) {
1055                         *errp = -EIO;
1056                         goto err;
1057                 }
1058                 if (buffer_new(&dummy)) {
1059                         J_ASSERT(create != 0);
1060                         J_ASSERT(handle != NULL);
1061
1062                         /*
1063                          * Now that we do not always journal data, we should
1064                          * keep in mind whether this should always journal the
1065                          * new buffer as metadata.  For now, regular file
1066                          * writes use ext4_get_block instead, so it's not a
1067                          * problem.
1068                          */
1069                         lock_buffer(bh);
1070                         BUFFER_TRACE(bh, "call get_create_access");
1071                         fatal = ext4_journal_get_create_access(handle, bh);
1072                         if (!fatal && !buffer_uptodate(bh)) {
1073                                 memset(bh->b_data,0,inode->i_sb->s_blocksize);
1074                                 set_buffer_uptodate(bh);
1075                         }
1076                         unlock_buffer(bh);
1077                         BUFFER_TRACE(bh, "call ext4_journal_dirty_metadata");
1078                         err = ext4_journal_dirty_metadata(handle, bh);
1079                         if (!fatal)
1080                                 fatal = err;
1081                 } else {
1082                         BUFFER_TRACE(bh, "not a new buffer");
1083                 }
1084                 if (fatal) {
1085                         *errp = fatal;
1086                         brelse(bh);
1087                         bh = NULL;
1088                 }
1089                 return bh;
1090         }
1091 err:
1092         return NULL;
1093 }
1094
1095 struct buffer_head *ext4_bread(handle_t *handle, struct inode *inode,
1096                                ext4_lblk_t block, int create, int *err)
1097 {
1098         struct buffer_head * bh;
1099
1100         bh = ext4_getblk(handle, inode, block, create, err);
1101         if (!bh)
1102                 return bh;
1103         if (buffer_uptodate(bh))
1104                 return bh;
1105         ll_rw_block(READ_META, 1, &bh);
1106         wait_on_buffer(bh);
1107         if (buffer_uptodate(bh))
1108                 return bh;
1109         put_bh(bh);
1110         *err = -EIO;
1111         return NULL;
1112 }
1113
1114 static int walk_page_buffers(   handle_t *handle,
1115                                 struct buffer_head *head,
1116                                 unsigned from,
1117                                 unsigned to,
1118                                 int *partial,
1119                                 int (*fn)(      handle_t *handle,
1120                                                 struct buffer_head *bh))
1121 {
1122         struct buffer_head *bh;
1123         unsigned block_start, block_end;
1124         unsigned blocksize = head->b_size;
1125         int err, ret = 0;
1126         struct buffer_head *next;
1127
1128         for (   bh = head, block_start = 0;
1129                 ret == 0 && (bh != head || !block_start);
1130                 block_start = block_end, bh = next)
1131         {
1132                 next = bh->b_this_page;
1133                 block_end = block_start + blocksize;
1134                 if (block_end <= from || block_start >= to) {
1135                         if (partial && !buffer_uptodate(bh))
1136                                 *partial = 1;
1137                         continue;
1138                 }
1139                 err = (*fn)(handle, bh);
1140                 if (!ret)
1141                         ret = err;
1142         }
1143         return ret;
1144 }
1145
1146 /*
1147  * To preserve ordering, it is essential that the hole instantiation and
1148  * the data write be encapsulated in a single transaction.  We cannot
1149  * close off a transaction and start a new one between the ext4_get_block()
1150  * and the commit_write().  So doing the jbd2_journal_start at the start of
1151  * prepare_write() is the right place.
1152  *
1153  * Also, this function can nest inside ext4_writepage() ->
1154  * block_write_full_page(). In that case, we *know* that ext4_writepage()
1155  * has generated enough buffer credits to do the whole page.  So we won't
1156  * block on the journal in that case, which is good, because the caller may
1157  * be PF_MEMALLOC.
1158  *
1159  * By accident, ext4 can be reentered when a transaction is open via
1160  * quota file writes.  If we were to commit the transaction while thus
1161  * reentered, there can be a deadlock - we would be holding a quota
1162  * lock, and the commit would never complete if another thread had a
1163  * transaction open and was blocking on the quota lock - a ranking
1164  * violation.
1165  *
1166  * So what we do is to rely on the fact that jbd2_journal_stop/journal_start
1167  * will _not_ run commit under these circumstances because handle->h_ref
1168  * is elevated.  We'll still have enough credits for the tiny quotafile
1169  * write.
1170  */
1171 static int do_journal_get_write_access(handle_t *handle,
1172                                         struct buffer_head *bh)
1173 {
1174         if (!buffer_mapped(bh) || buffer_freed(bh))
1175                 return 0;
1176         return ext4_journal_get_write_access(handle, bh);
1177 }
1178
1179 static int ext4_write_begin(struct file *file, struct address_space *mapping,
1180                                 loff_t pos, unsigned len, unsigned flags,
1181                                 struct page **pagep, void **fsdata)
1182 {
1183         struct inode *inode = mapping->host;
1184         int ret, needed_blocks = ext4_writepage_trans_blocks(inode);
1185         handle_t *handle;
1186         int retries = 0;
1187         struct page *page;
1188         pgoff_t index;
1189         unsigned from, to;
1190
1191         index = pos >> PAGE_CACHE_SHIFT;
1192         from = pos & (PAGE_CACHE_SIZE - 1);
1193         to = from + len;
1194
1195 retry:
1196         page = __grab_cache_page(mapping, index);
1197         if (!page)
1198                 return -ENOMEM;
1199         *pagep = page;
1200
1201         handle = ext4_journal_start(inode, needed_blocks);
1202         if (IS_ERR(handle)) {
1203                 unlock_page(page);
1204                 page_cache_release(page);
1205                 ret = PTR_ERR(handle);
1206                 goto out;
1207         }
1208
1209         ret = block_write_begin(file, mapping, pos, len, flags, pagep, fsdata,
1210                                                         ext4_get_block);
1211
1212         if (!ret && ext4_should_journal_data(inode)) {
1213                 ret = walk_page_buffers(handle, page_buffers(page),
1214                                 from, to, NULL, do_journal_get_write_access);
1215         }
1216
1217         if (ret) {
1218                 ext4_journal_stop(handle);
1219                 unlock_page(page);
1220                 page_cache_release(page);
1221         }
1222
1223         if (ret == -ENOSPC && ext4_should_retry_alloc(inode->i_sb, &retries))
1224                 goto retry;
1225 out:
1226         return ret;
1227 }
1228
1229 int ext4_journal_dirty_data(handle_t *handle, struct buffer_head *bh)
1230 {
1231         int err = jbd2_journal_dirty_data(handle, bh);
1232         if (err)
1233                 ext4_journal_abort_handle(__FUNCTION__, __FUNCTION__,
1234                                                 bh, handle, err);
1235         return err;
1236 }
1237
1238 /* For write_end() in data=journal mode */
1239 static int write_end_fn(handle_t *handle, struct buffer_head *bh)
1240 {
1241         if (!buffer_mapped(bh) || buffer_freed(bh))
1242                 return 0;
1243         set_buffer_uptodate(bh);
1244         return ext4_journal_dirty_metadata(handle, bh);
1245 }
1246
1247 /*
1248  * Generic write_end handler for ordered and writeback ext4 journal modes.
1249  * We can't use generic_write_end, because that unlocks the page and we need to
1250  * unlock the page after ext4_journal_stop, but ext4_journal_stop must run
1251  * after block_write_end.
1252  */
1253 static int ext4_generic_write_end(struct file *file,
1254                                 struct address_space *mapping,
1255                                 loff_t pos, unsigned len, unsigned copied,
1256                                 struct page *page, void *fsdata)
1257 {
1258         struct inode *inode = file->f_mapping->host;
1259
1260         copied = block_write_end(file, mapping, pos, len, copied, page, fsdata);
1261
1262         if (pos+copied > inode->i_size) {
1263                 i_size_write(inode, pos+copied);
1264                 mark_inode_dirty(inode);
1265         }
1266
1267         return copied;
1268 }
1269
1270 /*
1271  * We need to pick up the new inode size which generic_commit_write gave us
1272  * `file' can be NULL - eg, when called from page_symlink().
1273  *
1274  * ext4 never places buffers on inode->i_mapping->private_list.  metadata
1275  * buffers are managed internally.
1276  */
1277 static int ext4_ordered_write_end(struct file *file,
1278                                 struct address_space *mapping,
1279                                 loff_t pos, unsigned len, unsigned copied,
1280                                 struct page *page, void *fsdata)
1281 {
1282         handle_t *handle = ext4_journal_current_handle();
1283         struct inode *inode = file->f_mapping->host;
1284         unsigned from, to;
1285         int ret = 0, ret2;
1286
1287         from = pos & (PAGE_CACHE_SIZE - 1);
1288         to = from + len;
1289
1290         ret = walk_page_buffers(handle, page_buffers(page),
1291                 from, to, NULL, ext4_journal_dirty_data);
1292
1293         if (ret == 0) {
1294                 /*
1295                  * generic_write_end() will run mark_inode_dirty() if i_size
1296                  * changes.  So let's piggyback the i_disksize mark_inode_dirty
1297                  * into that.
1298                  */
1299                 loff_t new_i_size;
1300
1301                 new_i_size = pos + copied;
1302                 if (new_i_size > EXT4_I(inode)->i_disksize)
1303                         EXT4_I(inode)->i_disksize = new_i_size;
1304                 copied = ext4_generic_write_end(file, mapping, pos, len, copied,
1305                                                         page, fsdata);
1306                 if (copied < 0)
1307                         ret = copied;
1308         }
1309         ret2 = ext4_journal_stop(handle);
1310         if (!ret)
1311                 ret = ret2;
1312         unlock_page(page);
1313         page_cache_release(page);
1314
1315         return ret ? ret : copied;
1316 }
1317
1318 static int ext4_writeback_write_end(struct file *file,
1319                                 struct address_space *mapping,
1320                                 loff_t pos, unsigned len, unsigned copied,
1321                                 struct page *page, void *fsdata)
1322 {
1323         handle_t *handle = ext4_journal_current_handle();
1324         struct inode *inode = file->f_mapping->host;
1325         int ret = 0, ret2;
1326         loff_t new_i_size;
1327
1328         new_i_size = pos + copied;
1329         if (new_i_size > EXT4_I(inode)->i_disksize)
1330                 EXT4_I(inode)->i_disksize = new_i_size;
1331
1332         copied = ext4_generic_write_end(file, mapping, pos, len, copied,
1333                                                         page, fsdata);
1334         if (copied < 0)
1335                 ret = copied;
1336
1337         ret2 = ext4_journal_stop(handle);
1338         if (!ret)
1339                 ret = ret2;
1340         unlock_page(page);
1341         page_cache_release(page);
1342
1343         return ret ? ret : copied;
1344 }
1345
1346 static int ext4_journalled_write_end(struct file *file,
1347                                 struct address_space *mapping,
1348                                 loff_t pos, unsigned len, unsigned copied,
1349                                 struct page *page, void *fsdata)
1350 {
1351         handle_t *handle = ext4_journal_current_handle();
1352         struct inode *inode = mapping->host;
1353         int ret = 0, ret2;
1354         int partial = 0;
1355         unsigned from, to;
1356
1357         from = pos & (PAGE_CACHE_SIZE - 1);
1358         to = from + len;
1359
1360         if (copied < len) {
1361                 if (!PageUptodate(page))
1362                         copied = 0;
1363                 page_zero_new_buffers(page, from+copied, to);
1364         }
1365
1366         ret = walk_page_buffers(handle, page_buffers(page), from,
1367                                 to, &partial, write_end_fn);
1368         if (!partial)
1369                 SetPageUptodate(page);
1370         if (pos+copied > inode->i_size)
1371                 i_size_write(inode, pos+copied);
1372         EXT4_I(inode)->i_state |= EXT4_STATE_JDATA;
1373         if (inode->i_size > EXT4_I(inode)->i_disksize) {
1374                 EXT4_I(inode)->i_disksize = inode->i_size;
1375                 ret2 = ext4_mark_inode_dirty(handle, inode);
1376                 if (!ret)
1377                         ret = ret2;
1378         }
1379
1380         ret2 = ext4_journal_stop(handle);
1381         if (!ret)
1382                 ret = ret2;
1383         unlock_page(page);
1384         page_cache_release(page);
1385
1386         return ret ? ret : copied;
1387 }
1388
1389 /*
1390  * bmap() is special.  It gets used by applications such as lilo and by
1391  * the swapper to find the on-disk block of a specific piece of data.
1392  *
1393  * Naturally, this is dangerous if the block concerned is still in the
1394  * journal.  If somebody makes a swapfile on an ext4 data-journaling
1395  * filesystem and enables swap, then they may get a nasty shock when the
1396  * data getting swapped to that swapfile suddenly gets overwritten by
1397  * the original zero's written out previously to the journal and
1398  * awaiting writeback in the kernel's buffer cache.
1399  *
1400  * So, if we see any bmap calls here on a modified, data-journaled file,
1401  * take extra steps to flush any blocks which might be in the cache.
1402  */
1403 static sector_t ext4_bmap(struct address_space *mapping, sector_t block)
1404 {
1405         struct inode *inode = mapping->host;
1406         journal_t *journal;
1407         int err;
1408
1409         if (EXT4_I(inode)->i_state & EXT4_STATE_JDATA) {
1410                 /*
1411                  * This is a REALLY heavyweight approach, but the use of
1412                  * bmap on dirty files is expected to be extremely rare:
1413                  * only if we run lilo or swapon on a freshly made file
1414                  * do we expect this to happen.
1415                  *
1416                  * (bmap requires CAP_SYS_RAWIO so this does not
1417                  * represent an unprivileged user DOS attack --- we'd be
1418                  * in trouble if mortal users could trigger this path at
1419                  * will.)
1420                  *
1421                  * NB. EXT4_STATE_JDATA is not set on files other than
1422                  * regular files.  If somebody wants to bmap a directory
1423                  * or symlink and gets confused because the buffer
1424                  * hasn't yet been flushed to disk, they deserve
1425                  * everything they get.
1426                  */
1427
1428                 EXT4_I(inode)->i_state &= ~EXT4_STATE_JDATA;
1429                 journal = EXT4_JOURNAL(inode);
1430                 jbd2_journal_lock_updates(journal);
1431                 err = jbd2_journal_flush(journal);
1432                 jbd2_journal_unlock_updates(journal);
1433
1434                 if (err)
1435                         return 0;
1436         }
1437
1438         return generic_block_bmap(mapping,block,ext4_get_block);
1439 }
1440
1441 static int bget_one(handle_t *handle, struct buffer_head *bh)
1442 {
1443         get_bh(bh);
1444         return 0;
1445 }
1446
1447 static int bput_one(handle_t *handle, struct buffer_head *bh)
1448 {
1449         put_bh(bh);
1450         return 0;
1451 }
1452
1453 static int jbd2_journal_dirty_data_fn(handle_t *handle, struct buffer_head *bh)
1454 {
1455         if (buffer_mapped(bh))
1456                 return ext4_journal_dirty_data(handle, bh);
1457         return 0;
1458 }
1459
1460 /*
1461  * Note that we always start a transaction even if we're not journalling
1462  * data.  This is to preserve ordering: any hole instantiation within
1463  * __block_write_full_page -> ext4_get_block() should be journalled
1464  * along with the data so we don't crash and then get metadata which
1465  * refers to old data.
1466  *
1467  * In all journalling modes block_write_full_page() will start the I/O.
1468  *
1469  * Problem:
1470  *
1471  *      ext4_writepage() -> kmalloc() -> __alloc_pages() -> page_launder() ->
1472  *              ext4_writepage()
1473  *
1474  * Similar for:
1475  *
1476  *      ext4_file_write() -> generic_file_write() -> __alloc_pages() -> ...
1477  *
1478  * Same applies to ext4_get_block().  We will deadlock on various things like
1479  * lock_journal and i_data_sem
1480  *
1481  * Setting PF_MEMALLOC here doesn't work - too many internal memory
1482  * allocations fail.
1483  *
1484  * 16May01: If we're reentered then journal_current_handle() will be
1485  *          non-zero. We simply *return*.
1486  *
1487  * 1 July 2001: @@@ FIXME:
1488  *   In journalled data mode, a data buffer may be metadata against the
1489  *   current transaction.  But the same file is part of a shared mapping
1490  *   and someone does a writepage() on it.
1491  *
1492  *   We will move the buffer onto the async_data list, but *after* it has
1493  *   been dirtied. So there's a small window where we have dirty data on
1494  *   BJ_Metadata.
1495  *
1496  *   Note that this only applies to the last partial page in the file.  The
1497  *   bit which block_write_full_page() uses prepare/commit for.  (That's
1498  *   broken code anyway: it's wrong for msync()).
1499  *
1500  *   It's a rare case: affects the final partial page, for journalled data
1501  *   where the file is subject to bith write() and writepage() in the same
1502  *   transction.  To fix it we'll need a custom block_write_full_page().
1503  *   We'll probably need that anyway for journalling writepage() output.
1504  *
1505  * We don't honour synchronous mounts for writepage().  That would be
1506  * disastrous.  Any write() or metadata operation will sync the fs for
1507  * us.
1508  *
1509  * AKPM2: if all the page's buffers are mapped to disk and !data=journal,
1510  * we don't need to open a transaction here.
1511  */
1512 static int ext4_ordered_writepage(struct page *page,
1513                                 struct writeback_control *wbc)
1514 {
1515         struct inode *inode = page->mapping->host;
1516         struct buffer_head *page_bufs;
1517         handle_t *handle = NULL;
1518         int ret = 0;
1519         int err;
1520
1521         J_ASSERT(PageLocked(page));
1522
1523         /*
1524          * We give up here if we're reentered, because it might be for a
1525          * different filesystem.
1526          */
1527         if (ext4_journal_current_handle())
1528                 goto out_fail;
1529
1530         handle = ext4_journal_start(inode, ext4_writepage_trans_blocks(inode));
1531
1532         if (IS_ERR(handle)) {
1533                 ret = PTR_ERR(handle);
1534                 goto out_fail;
1535         }
1536
1537         if (!page_has_buffers(page)) {
1538                 create_empty_buffers(page, inode->i_sb->s_blocksize,
1539                                 (1 << BH_Dirty)|(1 << BH_Uptodate));
1540         }
1541         page_bufs = page_buffers(page);
1542         walk_page_buffers(handle, page_bufs, 0,
1543                         PAGE_CACHE_SIZE, NULL, bget_one);
1544
1545         ret = block_write_full_page(page, ext4_get_block, wbc);
1546
1547         /*
1548          * The page can become unlocked at any point now, and
1549          * truncate can then come in and change things.  So we
1550          * can't touch *page from now on.  But *page_bufs is
1551          * safe due to elevated refcount.
1552          */
1553
1554         /*
1555          * And attach them to the current transaction.  But only if
1556          * block_write_full_page() succeeded.  Otherwise they are unmapped,
1557          * and generally junk.
1558          */
1559         if (ret == 0) {
1560                 err = walk_page_buffers(handle, page_bufs, 0, PAGE_CACHE_SIZE,
1561                                         NULL, jbd2_journal_dirty_data_fn);
1562                 if (!ret)
1563                         ret = err;
1564         }
1565         walk_page_buffers(handle, page_bufs, 0,
1566                         PAGE_CACHE_SIZE, NULL, bput_one);
1567         err = ext4_journal_stop(handle);
1568         if (!ret)
1569                 ret = err;
1570         return ret;
1571
1572 out_fail:
1573         redirty_page_for_writepage(wbc, page);
1574         unlock_page(page);
1575         return ret;
1576 }
1577
1578 static int ext4_writeback_writepage(struct page *page,
1579                                 struct writeback_control *wbc)
1580 {
1581         struct inode *inode = page->mapping->host;
1582         handle_t *handle = NULL;
1583         int ret = 0;
1584         int err;
1585
1586         if (ext4_journal_current_handle())
1587                 goto out_fail;
1588
1589         handle = ext4_journal_start(inode, ext4_writepage_trans_blocks(inode));
1590         if (IS_ERR(handle)) {
1591                 ret = PTR_ERR(handle);
1592                 goto out_fail;
1593         }
1594
1595         if (test_opt(inode->i_sb, NOBH) && ext4_should_writeback_data(inode))
1596                 ret = nobh_writepage(page, ext4_get_block, wbc);
1597         else
1598                 ret = block_write_full_page(page, ext4_get_block, wbc);
1599
1600         err = ext4_journal_stop(handle);
1601         if (!ret)
1602                 ret = err;
1603         return ret;
1604
1605 out_fail:
1606         redirty_page_for_writepage(wbc, page);
1607         unlock_page(page);
1608         return ret;
1609 }
1610
1611 static int ext4_journalled_writepage(struct page *page,
1612                                 struct writeback_control *wbc)
1613 {
1614         struct inode *inode = page->mapping->host;
1615         handle_t *handle = NULL;
1616         int ret = 0;
1617         int err;
1618
1619         if (ext4_journal_current_handle())
1620                 goto no_write;
1621
1622         handle = ext4_journal_start(inode, ext4_writepage_trans_blocks(inode));
1623         if (IS_ERR(handle)) {
1624                 ret = PTR_ERR(handle);
1625                 goto no_write;
1626         }
1627
1628         if (!page_has_buffers(page) || PageChecked(page)) {
1629                 /*
1630                  * It's mmapped pagecache.  Add buffers and journal it.  There
1631                  * doesn't seem much point in redirtying the page here.
1632                  */
1633                 ClearPageChecked(page);
1634                 ret = block_prepare_write(page, 0, PAGE_CACHE_SIZE,
1635                                         ext4_get_block);
1636                 if (ret != 0) {
1637                         ext4_journal_stop(handle);
1638                         goto out_unlock;
1639                 }
1640                 ret = walk_page_buffers(handle, page_buffers(page), 0,
1641                         PAGE_CACHE_SIZE, NULL, do_journal_get_write_access);
1642
1643                 err = walk_page_buffers(handle, page_buffers(page), 0,
1644                                 PAGE_CACHE_SIZE, NULL, write_end_fn);
1645                 if (ret == 0)
1646                         ret = err;
1647                 EXT4_I(inode)->i_state |= EXT4_STATE_JDATA;
1648                 unlock_page(page);
1649         } else {
1650                 /*
1651                  * It may be a page full of checkpoint-mode buffers.  We don't
1652                  * really know unless we go poke around in the buffer_heads.
1653                  * But block_write_full_page will do the right thing.
1654                  */
1655                 ret = block_write_full_page(page, ext4_get_block, wbc);
1656         }
1657         err = ext4_journal_stop(handle);
1658         if (!ret)
1659                 ret = err;
1660 out:
1661         return ret;
1662
1663 no_write:
1664         redirty_page_for_writepage(wbc, page);
1665 out_unlock:
1666         unlock_page(page);
1667         goto out;
1668 }
1669
1670 static int ext4_readpage(struct file *file, struct page *page)
1671 {
1672         return mpage_readpage(page, ext4_get_block);
1673 }
1674
1675 static int
1676 ext4_readpages(struct file *file, struct address_space *mapping,
1677                 struct list_head *pages, unsigned nr_pages)
1678 {
1679         return mpage_readpages(mapping, pages, nr_pages, ext4_get_block);
1680 }
1681
1682 static void ext4_invalidatepage(struct page *page, unsigned long offset)
1683 {
1684         journal_t *journal = EXT4_JOURNAL(page->mapping->host);
1685
1686         /*
1687          * If it's a full truncate we just forget about the pending dirtying
1688          */
1689         if (offset == 0)
1690                 ClearPageChecked(page);
1691
1692         jbd2_journal_invalidatepage(journal, page, offset);
1693 }
1694
1695 static int ext4_releasepage(struct page *page, gfp_t wait)
1696 {
1697         journal_t *journal = EXT4_JOURNAL(page->mapping->host);
1698
1699         WARN_ON(PageChecked(page));
1700         if (!page_has_buffers(page))
1701                 return 0;
1702         return jbd2_journal_try_to_free_buffers(journal, page, wait);
1703 }
1704
1705 /*
1706  * If the O_DIRECT write will extend the file then add this inode to the
1707  * orphan list.  So recovery will truncate it back to the original size
1708  * if the machine crashes during the write.
1709  *
1710  * If the O_DIRECT write is intantiating holes inside i_size and the machine
1711  * crashes then stale disk data _may_ be exposed inside the file. But current
1712  * VFS code falls back into buffered path in that case so we are safe.
1713  */
1714 static ssize_t ext4_direct_IO(int rw, struct kiocb *iocb,
1715                         const struct iovec *iov, loff_t offset,
1716                         unsigned long nr_segs)
1717 {
1718         struct file *file = iocb->ki_filp;
1719         struct inode *inode = file->f_mapping->host;
1720         struct ext4_inode_info *ei = EXT4_I(inode);
1721         handle_t *handle;
1722         ssize_t ret;
1723         int orphan = 0;
1724         size_t count = iov_length(iov, nr_segs);
1725
1726         if (rw == WRITE) {
1727                 loff_t final_size = offset + count;
1728
1729                 if (final_size > inode->i_size) {
1730                         /* Credits for sb + inode write */
1731                         handle = ext4_journal_start(inode, 2);
1732                         if (IS_ERR(handle)) {
1733                                 ret = PTR_ERR(handle);
1734                                 goto out;
1735                         }
1736                         ret = ext4_orphan_add(handle, inode);
1737                         if (ret) {
1738                                 ext4_journal_stop(handle);
1739                                 goto out;
1740                         }
1741                         orphan = 1;
1742                         ei->i_disksize = inode->i_size;
1743                         ext4_journal_stop(handle);
1744                 }
1745         }
1746
1747         ret = blockdev_direct_IO(rw, iocb, inode, inode->i_sb->s_bdev, iov,
1748                                  offset, nr_segs,
1749                                  ext4_get_block, NULL);
1750
1751         if (orphan) {
1752                 int err;
1753
1754                 /* Credits for sb + inode write */
1755                 handle = ext4_journal_start(inode, 2);
1756                 if (IS_ERR(handle)) {
1757                         /* This is really bad luck. We've written the data
1758                          * but cannot extend i_size. Bail out and pretend
1759                          * the write failed... */
1760                         ret = PTR_ERR(handle);
1761                         goto out;
1762                 }
1763                 if (inode->i_nlink)
1764                         ext4_orphan_del(handle, inode);
1765                 if (ret > 0) {
1766                         loff_t end = offset + ret;
1767                         if (end > inode->i_size) {
1768                                 ei->i_disksize = end;
1769                                 i_size_write(inode, end);
1770                                 /*
1771                                  * We're going to return a positive `ret'
1772                                  * here due to non-zero-length I/O, so there's
1773                                  * no way of reporting error returns from
1774                                  * ext4_mark_inode_dirty() to userspace.  So
1775                                  * ignore it.
1776                                  */
1777                                 ext4_mark_inode_dirty(handle, inode);
1778                         }
1779                 }
1780                 err = ext4_journal_stop(handle);
1781                 if (ret == 0)
1782                         ret = err;
1783         }
1784 out:
1785         return ret;
1786 }
1787
1788 /*
1789  * Pages can be marked dirty completely asynchronously from ext4's journalling
1790  * activity.  By filemap_sync_pte(), try_to_unmap_one(), etc.  We cannot do
1791  * much here because ->set_page_dirty is called under VFS locks.  The page is
1792  * not necessarily locked.
1793  *
1794  * We cannot just dirty the page and leave attached buffers clean, because the
1795  * buffers' dirty state is "definitive".  We cannot just set the buffers dirty
1796  * or jbddirty because all the journalling code will explode.
1797  *
1798  * So what we do is to mark the page "pending dirty" and next time writepage
1799  * is called, propagate that into the buffers appropriately.
1800  */
1801 static int ext4_journalled_set_page_dirty(struct page *page)
1802 {
1803         SetPageChecked(page);
1804         return __set_page_dirty_nobuffers(page);
1805 }
1806
1807 static const struct address_space_operations ext4_ordered_aops = {
1808         .readpage       = ext4_readpage,
1809         .readpages      = ext4_readpages,
1810         .writepage      = ext4_ordered_writepage,
1811         .sync_page      = block_sync_page,
1812         .write_begin    = ext4_write_begin,
1813         .write_end      = ext4_ordered_write_end,
1814         .bmap           = ext4_bmap,
1815         .invalidatepage = ext4_invalidatepage,
1816         .releasepage    = ext4_releasepage,
1817         .direct_IO      = ext4_direct_IO,
1818         .migratepage    = buffer_migrate_page,
1819 };
1820
1821 static const struct address_space_operations ext4_writeback_aops = {
1822         .readpage       = ext4_readpage,
1823         .readpages      = ext4_readpages,
1824         .writepage      = ext4_writeback_writepage,
1825         .sync_page      = block_sync_page,
1826         .write_begin    = ext4_write_begin,
1827         .write_end      = ext4_writeback_write_end,
1828         .bmap           = ext4_bmap,
1829         .invalidatepage = ext4_invalidatepage,
1830         .releasepage    = ext4_releasepage,
1831         .direct_IO      = ext4_direct_IO,
1832         .migratepage    = buffer_migrate_page,
1833 };
1834
1835 static const struct address_space_operations ext4_journalled_aops = {
1836         .readpage       = ext4_readpage,
1837         .readpages      = ext4_readpages,
1838         .writepage      = ext4_journalled_writepage,
1839         .sync_page      = block_sync_page,
1840         .write_begin    = ext4_write_begin,
1841         .write_end      = ext4_journalled_write_end,
1842         .set_page_dirty = ext4_journalled_set_page_dirty,
1843         .bmap           = ext4_bmap,
1844         .invalidatepage = ext4_invalidatepage,
1845         .releasepage    = ext4_releasepage,
1846 };
1847
1848 void ext4_set_aops(struct inode *inode)
1849 {
1850         if (ext4_should_order_data(inode))
1851                 inode->i_mapping->a_ops = &ext4_ordered_aops;
1852         else if (ext4_should_writeback_data(inode))
1853                 inode->i_mapping->a_ops = &ext4_writeback_aops;
1854         else
1855                 inode->i_mapping->a_ops = &ext4_journalled_aops;
1856 }
1857
1858 /*
1859  * ext4_block_truncate_page() zeroes out a mapping from file offset `from'
1860  * up to the end of the block which corresponds to `from'.
1861  * This required during truncate. We need to physically zero the tail end
1862  * of that block so it doesn't yield old data if the file is later grown.
1863  */
1864 int ext4_block_truncate_page(handle_t *handle, struct page *page,
1865                 struct address_space *mapping, loff_t from)
1866 {
1867         ext4_fsblk_t index = from >> PAGE_CACHE_SHIFT;
1868         unsigned offset = from & (PAGE_CACHE_SIZE-1);
1869         unsigned blocksize, length, pos;
1870         ext4_lblk_t iblock;
1871         struct inode *inode = mapping->host;
1872         struct buffer_head *bh;
1873         int err = 0;
1874
1875         blocksize = inode->i_sb->s_blocksize;
1876         length = blocksize - (offset & (blocksize - 1));
1877         iblock = index << (PAGE_CACHE_SHIFT - inode->i_sb->s_blocksize_bits);
1878
1879         /*
1880          * For "nobh" option,  we can only work if we don't need to
1881          * read-in the page - otherwise we create buffers to do the IO.
1882          */
1883         if (!page_has_buffers(page) && test_opt(inode->i_sb, NOBH) &&
1884              ext4_should_writeback_data(inode) && PageUptodate(page)) {
1885                 zero_user(page, offset, length);
1886                 set_page_dirty(page);
1887                 goto unlock;
1888         }
1889
1890         if (!page_has_buffers(page))
1891                 create_empty_buffers(page, blocksize, 0);
1892
1893         /* Find the buffer that contains "offset" */
1894         bh = page_buffers(page);
1895         pos = blocksize;
1896         while (offset >= pos) {
1897                 bh = bh->b_this_page;
1898                 iblock++;
1899                 pos += blocksize;
1900         }
1901
1902         err = 0;
1903         if (buffer_freed(bh)) {
1904                 BUFFER_TRACE(bh, "freed: skip");
1905                 goto unlock;
1906         }
1907
1908         if (!buffer_mapped(bh)) {
1909                 BUFFER_TRACE(bh, "unmapped");
1910                 ext4_get_block(inode, iblock, bh, 0);
1911                 /* unmapped? It's a hole - nothing to do */
1912                 if (!buffer_mapped(bh)) {
1913                         BUFFER_TRACE(bh, "still unmapped");
1914                         goto unlock;
1915                 }
1916         }
1917
1918         /* Ok, it's mapped. Make sure it's up-to-date */
1919         if (PageUptodate(page))
1920                 set_buffer_uptodate(bh);
1921
1922         if (!buffer_uptodate(bh)) {
1923                 err = -EIO;
1924                 ll_rw_block(READ, 1, &bh);
1925                 wait_on_buffer(bh);
1926                 /* Uhhuh. Read error. Complain and punt. */
1927                 if (!buffer_uptodate(bh))
1928                         goto unlock;
1929         }
1930
1931         if (ext4_should_journal_data(inode)) {
1932                 BUFFER_TRACE(bh, "get write access");
1933                 err = ext4_journal_get_write_access(handle, bh);
1934                 if (err)
1935                         goto unlock;
1936         }
1937
1938         zero_user(page, offset, length);
1939
1940         BUFFER_TRACE(bh, "zeroed end of block");
1941
1942         err = 0;
1943         if (ext4_should_journal_data(inode)) {
1944                 err = ext4_journal_dirty_metadata(handle, bh);
1945         } else {
1946                 if (ext4_should_order_data(inode))
1947                         err = ext4_journal_dirty_data(handle, bh);
1948                 mark_buffer_dirty(bh);
1949         }
1950
1951 unlock:
1952         unlock_page(page);
1953         page_cache_release(page);
1954         return err;
1955 }
1956
1957 /*
1958  * Probably it should be a library function... search for first non-zero word
1959  * or memcmp with zero_page, whatever is better for particular architecture.
1960  * Linus?
1961  */
1962 static inline int all_zeroes(__le32 *p, __le32 *q)
1963 {
1964         while (p < q)
1965                 if (*p++)
1966                         return 0;
1967         return 1;
1968 }
1969
1970 /**
1971  *      ext4_find_shared - find the indirect blocks for partial truncation.
1972  *      @inode:   inode in question
1973  *      @depth:   depth of the affected branch
1974  *      @offsets: offsets of pointers in that branch (see ext4_block_to_path)
1975  *      @chain:   place to store the pointers to partial indirect blocks
1976  *      @top:     place to the (detached) top of branch
1977  *
1978  *      This is a helper function used by ext4_truncate().
1979  *
1980  *      When we do truncate() we may have to clean the ends of several
1981  *      indirect blocks but leave the blocks themselves alive. Block is
1982  *      partially truncated if some data below the new i_size is refered
1983  *      from it (and it is on the path to the first completely truncated
1984  *      data block, indeed).  We have to free the top of that path along
1985  *      with everything to the right of the path. Since no allocation
1986  *      past the truncation point is possible until ext4_truncate()
1987  *      finishes, we may safely do the latter, but top of branch may
1988  *      require special attention - pageout below the truncation point
1989  *      might try to populate it.
1990  *
1991  *      We atomically detach the top of branch from the tree, store the
1992  *      block number of its root in *@top, pointers to buffer_heads of
1993  *      partially truncated blocks - in @chain[].bh and pointers to
1994  *      their last elements that should not be removed - in
1995  *      @chain[].p. Return value is the pointer to last filled element
1996  *      of @chain.
1997  *
1998  *      The work left to caller to do the actual freeing of subtrees:
1999  *              a) free the subtree starting from *@top
2000  *              b) free the subtrees whose roots are stored in
2001  *                      (@chain[i].p+1 .. end of @chain[i].bh->b_data)
2002  *              c) free the subtrees growing from the inode past the @chain[0].
2003  *                      (no partially truncated stuff there).  */
2004
2005 static Indirect *ext4_find_shared(struct inode *inode, int depth,
2006                         ext4_lblk_t offsets[4], Indirect chain[4], __le32 *top)
2007 {
2008         Indirect *partial, *p;
2009         int k, err;
2010
2011         *top = 0;
2012         /* Make k index the deepest non-null offest + 1 */
2013         for (k = depth; k > 1 && !offsets[k-1]; k--)
2014                 ;
2015         partial = ext4_get_branch(inode, k, offsets, chain, &err);
2016         /* Writer: pointers */
2017         if (!partial)
2018                 partial = chain + k-1;
2019         /*
2020          * If the branch acquired continuation since we've looked at it -
2021          * fine, it should all survive and (new) top doesn't belong to us.
2022          */
2023         if (!partial->key && *partial->p)
2024                 /* Writer: end */
2025                 goto no_top;
2026         for (p=partial; p>chain && all_zeroes((__le32*)p->bh->b_data,p->p); p--)
2027                 ;
2028         /*
2029          * OK, we've found the last block that must survive. The rest of our
2030          * branch should be detached before unlocking. However, if that rest
2031          * of branch is all ours and does not grow immediately from the inode
2032          * it's easier to cheat and just decrement partial->p.
2033          */
2034         if (p == chain + k - 1 && p > chain) {
2035                 p->p--;
2036         } else {
2037                 *top = *p->p;
2038                 /* Nope, don't do this in ext4.  Must leave the tree intact */
2039 #if 0
2040                 *p->p = 0;
2041 #endif
2042         }
2043         /* Writer: end */
2044
2045         while(partial > p) {
2046                 brelse(partial->bh);
2047                 partial--;
2048         }
2049 no_top:
2050         return partial;
2051 }
2052
2053 /*
2054  * Zero a number of block pointers in either an inode or an indirect block.
2055  * If we restart the transaction we must again get write access to the
2056  * indirect block for further modification.
2057  *
2058  * We release `count' blocks on disk, but (last - first) may be greater
2059  * than `count' because there can be holes in there.
2060  */
2061 static void ext4_clear_blocks(handle_t *handle, struct inode *inode,
2062                 struct buffer_head *bh, ext4_fsblk_t block_to_free,
2063                 unsigned long count, __le32 *first, __le32 *last)
2064 {
2065         __le32 *p;
2066         if (try_to_extend_transaction(handle, inode)) {
2067                 if (bh) {
2068                         BUFFER_TRACE(bh, "call ext4_journal_dirty_metadata");
2069                         ext4_journal_dirty_metadata(handle, bh);
2070                 }
2071                 ext4_mark_inode_dirty(handle, inode);
2072                 ext4_journal_test_restart(handle, inode);
2073                 if (bh) {
2074                         BUFFER_TRACE(bh, "retaking write access");
2075                         ext4_journal_get_write_access(handle, bh);
2076                 }
2077         }
2078
2079         /*
2080          * Any buffers which are on the journal will be in memory. We find
2081          * them on the hash table so jbd2_journal_revoke() will run jbd2_journal_forget()
2082          * on them.  We've already detached each block from the file, so
2083          * bforget() in jbd2_journal_forget() should be safe.
2084          *
2085          * AKPM: turn on bforget in jbd2_journal_forget()!!!
2086          */
2087         for (p = first; p < last; p++) {
2088                 u32 nr = le32_to_cpu(*p);
2089                 if (nr) {
2090                         struct buffer_head *tbh;
2091
2092                         *p = 0;
2093                         tbh = sb_find_get_block(inode->i_sb, nr);
2094                         ext4_forget(handle, 0, inode, tbh, nr);
2095                 }
2096         }
2097
2098         ext4_free_blocks(handle, inode, block_to_free, count, 0);
2099 }
2100
2101 /**
2102  * ext4_free_data - free a list of data blocks
2103  * @handle:     handle for this transaction
2104  * @inode:      inode we are dealing with
2105  * @this_bh:    indirect buffer_head which contains *@first and *@last
2106  * @first:      array of block numbers
2107  * @last:       points immediately past the end of array
2108  *
2109  * We are freeing all blocks refered from that array (numbers are stored as
2110  * little-endian 32-bit) and updating @inode->i_blocks appropriately.
2111  *
2112  * We accumulate contiguous runs of blocks to free.  Conveniently, if these
2113  * blocks are contiguous then releasing them at one time will only affect one
2114  * or two bitmap blocks (+ group descriptor(s) and superblock) and we won't
2115  * actually use a lot of journal space.
2116  *
2117  * @this_bh will be %NULL if @first and @last point into the inode's direct
2118  * block pointers.
2119  */
2120 static void ext4_free_data(handle_t *handle, struct inode *inode,
2121                            struct buffer_head *this_bh,
2122                            __le32 *first, __le32 *last)
2123 {
2124         ext4_fsblk_t block_to_free = 0;    /* Starting block # of a run */
2125         unsigned long count = 0;            /* Number of blocks in the run */
2126         __le32 *block_to_free_p = NULL;     /* Pointer into inode/ind
2127                                                corresponding to
2128                                                block_to_free */
2129         ext4_fsblk_t nr;                    /* Current block # */
2130         __le32 *p;                          /* Pointer into inode/ind
2131                                                for current block */
2132         int err;
2133
2134         if (this_bh) {                          /* For indirect block */
2135                 BUFFER_TRACE(this_bh, "get_write_access");
2136                 err = ext4_journal_get_write_access(handle, this_bh);
2137                 /* Important: if we can't update the indirect pointers
2138                  * to the blocks, we can't free them. */
2139                 if (err)
2140                         return;
2141         }
2142
2143         for (p = first; p < last; p++) {
2144                 nr = le32_to_cpu(*p);
2145                 if (nr) {
2146                         /* accumulate blocks to free if they're contiguous */
2147                         if (count == 0) {
2148                                 block_to_free = nr;
2149                                 block_to_free_p = p;
2150                                 count = 1;
2151                         } else if (nr == block_to_free + count) {
2152                                 count++;
2153                         } else {
2154                                 ext4_clear_blocks(handle, inode, this_bh,
2155                                                   block_to_free,
2156                                                   count, block_to_free_p, p);
2157                                 block_to_free = nr;
2158                                 block_to_free_p = p;
2159                                 count = 1;
2160                         }
2161                 }
2162         }
2163
2164         if (count > 0)
2165                 ext4_clear_blocks(handle, inode, this_bh, block_to_free,
2166                                   count, block_to_free_p, p);
2167
2168         if (this_bh) {
2169                 BUFFER_TRACE(this_bh, "call ext4_journal_dirty_metadata");
2170                 ext4_journal_dirty_metadata(handle, this_bh);
2171         }
2172 }
2173
2174 /**
2175  *      ext4_free_branches - free an array of branches
2176  *      @handle: JBD handle for this transaction
2177  *      @inode: inode we are dealing with
2178  *      @parent_bh: the buffer_head which contains *@first and *@last
2179  *      @first: array of block numbers
2180  *      @last:  pointer immediately past the end of array
2181  *      @depth: depth of the branches to free
2182  *
2183  *      We are freeing all blocks refered from these branches (numbers are
2184  *      stored as little-endian 32-bit) and updating @inode->i_blocks
2185  *      appropriately.
2186  */
2187 static void ext4_free_branches(handle_t *handle, struct inode *inode,
2188                                struct buffer_head *parent_bh,
2189                                __le32 *first, __le32 *last, int depth)
2190 {
2191         ext4_fsblk_t nr;
2192         __le32 *p;
2193
2194         if (is_handle_aborted(handle))
2195                 return;
2196
2197         if (depth--) {
2198                 struct buffer_head *bh;
2199                 int addr_per_block = EXT4_ADDR_PER_BLOCK(inode->i_sb);
2200                 p = last;
2201                 while (--p >= first) {
2202                         nr = le32_to_cpu(*p);
2203                         if (!nr)
2204                                 continue;               /* A hole */
2205
2206                         /* Go read the buffer for the next level down */
2207                         bh = sb_bread(inode->i_sb, nr);
2208
2209                         /*
2210                          * A read failure? Report error and clear slot
2211                          * (should be rare).
2212                          */
2213                         if (!bh) {
2214                                 ext4_error(inode->i_sb, "ext4_free_branches",
2215                                            "Read failure, inode=%lu, block=%llu",
2216                                            inode->i_ino, nr);
2217                                 continue;
2218                         }
2219
2220                         /* This zaps the entire block.  Bottom up. */
2221                         BUFFER_TRACE(bh, "free child branches");
2222                         ext4_free_branches(handle, inode, bh,
2223                                            (__le32*)bh->b_data,
2224                                            (__le32*)bh->b_data + addr_per_block,
2225                                            depth);
2226
2227                         /*
2228                          * We've probably journalled the indirect block several
2229                          * times during the truncate.  But it's no longer
2230                          * needed and we now drop it from the transaction via
2231                          * jbd2_journal_revoke().
2232                          *
2233                          * That's easy if it's exclusively part of this
2234                          * transaction.  But if it's part of the committing
2235                          * transaction then jbd2_journal_forget() will simply
2236                          * brelse() it.  That means that if the underlying
2237                          * block is reallocated in ext4_get_block(),
2238                          * unmap_underlying_metadata() will find this block
2239                          * and will try to get rid of it.  damn, damn.
2240                          *
2241                          * If this block has already been committed to the
2242                          * journal, a revoke record will be written.  And
2243                          * revoke records must be emitted *before* clearing
2244                          * this block's bit in the bitmaps.
2245                          */
2246                         ext4_forget(handle, 1, inode, bh, bh->b_blocknr);
2247
2248                         /*
2249                          * Everything below this this pointer has been
2250                          * released.  Now let this top-of-subtree go.
2251                          *
2252                          * We want the freeing of this indirect block to be
2253                          * atomic in the journal with the updating of the
2254                          * bitmap block which owns it.  So make some room in
2255                          * the journal.
2256                          *
2257                          * We zero the parent pointer *after* freeing its
2258                          * pointee in the bitmaps, so if extend_transaction()
2259                          * for some reason fails to put the bitmap changes and
2260                          * the release into the same transaction, recovery
2261                          * will merely complain about releasing a free block,
2262                          * rather than leaking blocks.
2263                          */
2264                         if (is_handle_aborted(handle))
2265                                 return;
2266                         if (try_to_extend_transaction(handle, inode)) {
2267                                 ext4_mark_inode_dirty(handle, inode);
2268                                 ext4_journal_test_restart(handle, inode);
2269                         }
2270
2271                         ext4_free_blocks(handle, inode, nr, 1, 1);
2272
2273                         if (parent_bh) {
2274                                 /*
2275                                  * The block which we have just freed is
2276                                  * pointed to by an indirect block: journal it
2277                                  */
2278                                 BUFFER_TRACE(parent_bh, "get_write_access");
2279                                 if (!ext4_journal_get_write_access(handle,
2280                                                                    parent_bh)){
2281                                         *p = 0;
2282                                         BUFFER_TRACE(parent_bh,
2283                                         "call ext4_journal_dirty_metadata");
2284                                         ext4_journal_dirty_metadata(handle,
2285                                                                     parent_bh);
2286                                 }
2287                         }
2288                 }
2289         } else {
2290                 /* We have reached the bottom of the tree. */
2291                 BUFFER_TRACE(parent_bh, "free data blocks");
2292                 ext4_free_data(handle, inode, parent_bh, first, last);
2293         }
2294 }
2295
2296 /*
2297  * ext4_truncate()
2298  *
2299  * We block out ext4_get_block() block instantiations across the entire
2300  * transaction, and VFS/VM ensures that ext4_truncate() cannot run
2301  * simultaneously on behalf of the same inode.
2302  *
2303  * As we work through the truncate and commmit bits of it to the journal there
2304  * is one core, guiding principle: the file's tree must always be consistent on
2305  * disk.  We must be able to restart the truncate after a crash.
2306  *
2307  * The file's tree may be transiently inconsistent in memory (although it
2308  * probably isn't), but whenever we close off and commit a journal transaction,
2309  * the contents of (the filesystem + the journal) must be consistent and
2310  * restartable.  It's pretty simple, really: bottom up, right to left (although
2311  * left-to-right works OK too).
2312  *
2313  * Note that at recovery time, journal replay occurs *before* the restart of
2314  * truncate against the orphan inode list.
2315  *
2316  * The committed inode has the new, desired i_size (which is the same as
2317  * i_disksize in this case).  After a crash, ext4_orphan_cleanup() will see
2318  * that this inode's truncate did not complete and it will again call
2319  * ext4_truncate() to have another go.  So there will be instantiated blocks
2320  * to the right of the truncation point in a crashed ext4 filesystem.  But
2321  * that's fine - as long as they are linked from the inode, the post-crash
2322  * ext4_truncate() run will find them and release them.
2323  */
2324 void ext4_truncate(struct inode *inode)
2325 {
2326         handle_t *handle;
2327         struct ext4_inode_info *ei = EXT4_I(inode);
2328         __le32 *i_data = ei->i_data;
2329         int addr_per_block = EXT4_ADDR_PER_BLOCK(inode->i_sb);
2330         struct address_space *mapping = inode->i_mapping;
2331         ext4_lblk_t offsets[4];
2332         Indirect chain[4];
2333         Indirect *partial;
2334         __le32 nr = 0;
2335         int n;
2336         ext4_lblk_t last_block;
2337         unsigned blocksize = inode->i_sb->s_blocksize;
2338         struct page *page;
2339
2340         if (!(S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode) ||
2341             S_ISLNK(inode->i_mode)))
2342                 return;
2343         if (ext4_inode_is_fast_symlink(inode))
2344                 return;
2345         if (IS_APPEND(inode) || IS_IMMUTABLE(inode))
2346                 return;
2347
2348         /*
2349          * We have to lock the EOF page here, because lock_page() nests
2350          * outside jbd2_journal_start().
2351          */
2352         if ((inode->i_size & (blocksize - 1)) == 0) {
2353                 /* Block boundary? Nothing to do */
2354                 page = NULL;
2355         } else {
2356                 page = grab_cache_page(mapping,
2357                                 inode->i_size >> PAGE_CACHE_SHIFT);
2358                 if (!page)
2359                         return;
2360         }
2361
2362         if (EXT4_I(inode)->i_flags & EXT4_EXTENTS_FL) {
2363                 ext4_ext_truncate(inode, page);
2364                 return;
2365         }
2366
2367         handle = start_transaction(inode);
2368         if (IS_ERR(handle)) {
2369                 if (page) {
2370                         clear_highpage(page);
2371                         flush_dcache_page(page);
2372                         unlock_page(page);
2373                         page_cache_release(page);
2374                 }
2375                 return;         /* AKPM: return what? */
2376         }
2377
2378         last_block = (inode->i_size + blocksize-1)
2379                                         >> EXT4_BLOCK_SIZE_BITS(inode->i_sb);
2380
2381         if (page)
2382                 ext4_block_truncate_page(handle, page, mapping, inode->i_size);
2383
2384         n = ext4_block_to_path(inode, last_block, offsets, NULL);
2385         if (n == 0)
2386                 goto out_stop;  /* error */
2387
2388         /*
2389          * OK.  This truncate is going to happen.  We add the inode to the
2390          * orphan list, so that if this truncate spans multiple transactions,
2391          * and we crash, we will resume the truncate when the filesystem
2392          * recovers.  It also marks the inode dirty, to catch the new size.
2393          *
2394          * Implication: the file must always be in a sane, consistent
2395          * truncatable state while each transaction commits.
2396          */
2397         if (ext4_orphan_add(handle, inode))
2398                 goto out_stop;
2399
2400         /*
2401          * The orphan list entry will now protect us from any crash which
2402          * occurs before the truncate completes, so it is now safe to propagate
2403          * the new, shorter inode size (held for now in i_size) into the
2404          * on-disk inode. We do this via i_disksize, which is the value which
2405          * ext4 *really* writes onto the disk inode.
2406          */
2407         ei->i_disksize = inode->i_size;
2408
2409         /*
2410          * From here we block out all ext4_get_block() callers who want to
2411          * modify the block allocation tree.
2412          */
2413         down_write(&ei->i_data_sem);
2414
2415         if (n == 1) {           /* direct blocks */
2416                 ext4_free_data(handle, inode, NULL, i_data+offsets[0],
2417                                i_data + EXT4_NDIR_BLOCKS);
2418                 goto do_indirects;
2419         }
2420
2421         partial = ext4_find_shared(inode, n, offsets, chain, &nr);
2422         /* Kill the top of shared branch (not detached) */
2423         if (nr) {
2424                 if (partial == chain) {
2425                         /* Shared branch grows from the inode */
2426                         ext4_free_branches(handle, inode, NULL,
2427                                            &nr, &nr+1, (chain+n-1) - partial);
2428                         *partial->p = 0;
2429                         /*
2430                          * We mark the inode dirty prior to restart,
2431                          * and prior to stop.  No need for it here.
2432                          */
2433                 } else {
2434                         /* Shared branch grows from an indirect block */
2435                         BUFFER_TRACE(partial->bh, "get_write_access");
2436                         ext4_free_branches(handle, inode, partial->bh,
2437                                         partial->p,
2438                                         partial->p+1, (chain+n-1) - partial);
2439                 }
2440         }
2441         /* Clear the ends of indirect blocks on the shared branch */
2442         while (partial > chain) {
2443                 ext4_free_branches(handle, inode, partial->bh, partial->p + 1,
2444                                    (__le32*)partial->bh->b_data+addr_per_block,
2445                                    (chain+n-1) - partial);
2446                 BUFFER_TRACE(partial->bh, "call brelse");
2447                 brelse (partial->bh);
2448                 partial--;
2449         }
2450 do_indirects:
2451         /* Kill the remaining (whole) subtrees */
2452         switch (offsets[0]) {
2453         default:
2454                 nr = i_data[EXT4_IND_BLOCK];
2455                 if (nr) {
2456                         ext4_free_branches(handle, inode, NULL, &nr, &nr+1, 1);
2457                         i_data[EXT4_IND_BLOCK] = 0;
2458                 }
2459         case EXT4_IND_BLOCK:
2460                 nr = i_data[EXT4_DIND_BLOCK];
2461                 if (nr) {
2462                         ext4_free_branches(handle, inode, NULL, &nr, &nr+1, 2);
2463                         i_data[EXT4_DIND_BLOCK] = 0;
2464                 }
2465         case EXT4_DIND_BLOCK:
2466                 nr = i_data[EXT4_TIND_BLOCK];
2467                 if (nr) {
2468                         ext4_free_branches(handle, inode, NULL, &nr, &nr+1, 3);
2469                         i_data[EXT4_TIND_BLOCK] = 0;
2470                 }
2471         case EXT4_TIND_BLOCK:
2472                 ;
2473         }
2474
2475         ext4_discard_reservation(inode);
2476
2477         up_write(&ei->i_data_sem);
2478         inode->i_mtime = inode->i_ctime = ext4_current_time(inode);
2479         ext4_mark_inode_dirty(handle, inode);
2480
2481         /*
2482          * In a multi-transaction truncate, we only make the final transaction
2483          * synchronous
2484          */
2485         if (IS_SYNC(inode))
2486                 handle->h_sync = 1;
2487 out_stop:
2488         /*
2489          * If this was a simple ftruncate(), and the file will remain alive
2490          * then we need to clear up the orphan record which we created above.
2491          * However, if this was a real unlink then we were called by
2492          * ext4_delete_inode(), and we allow that function to clean up the
2493          * orphan info for us.
2494          */
2495         if (inode->i_nlink)
2496                 ext4_orphan_del(handle, inode);
2497
2498         ext4_journal_stop(handle);
2499 }
2500
2501 static ext4_fsblk_t ext4_get_inode_block(struct super_block *sb,
2502                 unsigned long ino, struct ext4_iloc *iloc)
2503 {
2504         unsigned long desc, group_desc;
2505         ext4_group_t block_group;
2506         unsigned long offset;
2507         ext4_fsblk_t block;
2508         struct buffer_head *bh;
2509         struct ext4_group_desc * gdp;
2510
2511         if (!ext4_valid_inum(sb, ino)) {
2512                 /*
2513                  * This error is already checked for in namei.c unless we are
2514                  * looking at an NFS filehandle, in which case no error
2515                  * report is needed
2516                  */
2517                 return 0;
2518         }
2519
2520         block_group = (ino - 1) / EXT4_INODES_PER_GROUP(sb);
2521         if (block_group >= EXT4_SB(sb)->s_groups_count) {
2522                 ext4_error(sb,"ext4_get_inode_block","group >= groups count");
2523                 return 0;
2524         }
2525         smp_rmb();
2526         group_desc = block_group >> EXT4_DESC_PER_BLOCK_BITS(sb);
2527         desc = block_group & (EXT4_DESC_PER_BLOCK(sb) - 1);
2528         bh = EXT4_SB(sb)->s_group_desc[group_desc];
2529         if (!bh) {
2530                 ext4_error (sb, "ext4_get_inode_block",
2531                             "Descriptor not loaded");
2532                 return 0;
2533         }
2534
2535         gdp = (struct ext4_group_desc *)((__u8 *)bh->b_data +
2536                 desc * EXT4_DESC_SIZE(sb));
2537         /*
2538          * Figure out the offset within the block group inode table
2539          */
2540         offset = ((ino - 1) % EXT4_INODES_PER_GROUP(sb)) *
2541                 EXT4_INODE_SIZE(sb);
2542         block = ext4_inode_table(sb, gdp) +
2543                 (offset >> EXT4_BLOCK_SIZE_BITS(sb));
2544
2545         iloc->block_group = block_group;
2546         iloc->offset = offset & (EXT4_BLOCK_SIZE(sb) - 1);
2547         return block;
2548 }
2549
2550 /*
2551  * ext4_get_inode_loc returns with an extra refcount against the inode's
2552  * underlying buffer_head on success. If 'in_mem' is true, we have all
2553  * data in memory that is needed to recreate the on-disk version of this
2554  * inode.
2555  */
2556 static int __ext4_get_inode_loc(struct inode *inode,
2557                                 struct ext4_iloc *iloc, int in_mem)
2558 {
2559         ext4_fsblk_t block;
2560         struct buffer_head *bh;
2561
2562         block = ext4_get_inode_block(inode->i_sb, inode->i_ino, iloc);
2563         if (!block)
2564                 return -EIO;
2565
2566         bh = sb_getblk(inode->i_sb, block);
2567         if (!bh) {
2568                 ext4_error (inode->i_sb, "ext4_get_inode_loc",
2569                                 "unable to read inode block - "
2570                                 "inode=%lu, block=%llu",
2571                                  inode->i_ino, block);
2572                 return -EIO;
2573         }
2574         if (!buffer_uptodate(bh)) {
2575                 lock_buffer(bh);
2576                 if (buffer_uptodate(bh)) {
2577                         /* someone brought it uptodate while we waited */
2578                         unlock_buffer(bh);
2579                         goto has_buffer;
2580                 }
2581
2582                 /*
2583                  * If we have all information of the inode in memory and this
2584                  * is the only valid inode in the block, we need not read the
2585                  * block.
2586                  */
2587                 if (in_mem) {
2588                         struct buffer_head *bitmap_bh;
2589                         struct ext4_group_desc *desc;
2590                         int inodes_per_buffer;
2591                         int inode_offset, i;
2592                         ext4_group_t block_group;
2593                         int start;
2594
2595                         block_group = (inode->i_ino - 1) /
2596                                         EXT4_INODES_PER_GROUP(inode->i_sb);
2597                         inodes_per_buffer = bh->b_size /
2598                                 EXT4_INODE_SIZE(inode->i_sb);
2599                         inode_offset = ((inode->i_ino - 1) %
2600                                         EXT4_INODES_PER_GROUP(inode->i_sb));
2601                         start = inode_offset & ~(inodes_per_buffer - 1);
2602
2603                         /* Is the inode bitmap in cache? */
2604                         desc = ext4_get_group_desc(inode->i_sb,
2605                                                 block_group, NULL);
2606                         if (!desc)
2607                                 goto make_io;
2608
2609                         bitmap_bh = sb_getblk(inode->i_sb,
2610                                 ext4_inode_bitmap(inode->i_sb, desc));
2611                         if (!bitmap_bh)
2612                                 goto make_io;
2613
2614                         /*
2615                          * If the inode bitmap isn't in cache then the
2616                          * optimisation may end up performing two reads instead
2617                          * of one, so skip it.
2618                          */
2619                         if (!buffer_uptodate(bitmap_bh)) {
2620                                 brelse(bitmap_bh);
2621                                 goto make_io;
2622                         }
2623                         for (i = start; i < start + inodes_per_buffer; i++) {
2624                                 if (i == inode_offset)
2625                                         continue;
2626                                 if (ext4_test_bit(i, bitmap_bh->b_data))
2627                                         break;
2628                         }
2629                         brelse(bitmap_bh);
2630                         if (i == start + inodes_per_buffer) {
2631                                 /* all other inodes are free, so skip I/O */
2632                                 memset(bh->b_data, 0, bh->b_size);
2633                                 set_buffer_uptodate(bh);
2634                                 unlock_buffer(bh);
2635                                 goto has_buffer;
2636                         }
2637                 }
2638
2639 make_io:
2640                 /*
2641                  * There are other valid inodes in the buffer, this inode
2642                  * has in-inode xattrs, or we don't have this inode in memory.
2643                  * Read the block from disk.
2644                  */
2645                 get_bh(bh);
2646                 bh->b_end_io = end_buffer_read_sync;
2647                 submit_bh(READ_META, bh);
2648                 wait_on_buffer(bh);
2649                 if (!buffer_uptodate(bh)) {
2650                         ext4_error(inode->i_sb, "ext4_get_inode_loc",
2651                                         "unable to read inode block - "
2652                                         "inode=%lu, block=%llu",
2653                                         inode->i_ino, block);
2654                         brelse(bh);
2655                         return -EIO;
2656                 }
2657         }
2658 has_buffer:
2659         iloc->bh = bh;
2660         return 0;
2661 }
2662
2663 int ext4_get_inode_loc(struct inode *inode, struct ext4_iloc *iloc)
2664 {
2665         /* We have all inode data except xattrs in memory here. */
2666         return __ext4_get_inode_loc(inode, iloc,
2667                 !(EXT4_I(inode)->i_state & EXT4_STATE_XATTR));
2668 }
2669
2670 void ext4_set_inode_flags(struct inode *inode)
2671 {
2672         unsigned int flags = EXT4_I(inode)->i_flags;
2673
2674         inode->i_flags &= ~(S_SYNC|S_APPEND|S_IMMUTABLE|S_NOATIME|S_DIRSYNC);
2675         if (flags & EXT4_SYNC_FL)
2676                 inode->i_flags |= S_SYNC;
2677         if (flags & EXT4_APPEND_FL)
2678                 inode->i_flags |= S_APPEND;
2679         if (flags & EXT4_IMMUTABLE_FL)
2680                 inode->i_flags |= S_IMMUTABLE;
2681         if (flags & EXT4_NOATIME_FL)
2682                 inode->i_flags |= S_NOATIME;
2683         if (flags & EXT4_DIRSYNC_FL)
2684                 inode->i_flags |= S_DIRSYNC;
2685 }
2686
2687 /* Propagate flags from i_flags to EXT4_I(inode)->i_flags */
2688 void ext4_get_inode_flags(struct ext4_inode_info *ei)
2689 {
2690         unsigned int flags = ei->vfs_inode.i_flags;
2691
2692         ei->i_flags &= ~(EXT4_SYNC_FL|EXT4_APPEND_FL|
2693                         EXT4_IMMUTABLE_FL|EXT4_NOATIME_FL|EXT4_DIRSYNC_FL);
2694         if (flags & S_SYNC)
2695                 ei->i_flags |= EXT4_SYNC_FL;
2696         if (flags & S_APPEND)
2697                 ei->i_flags |= EXT4_APPEND_FL;
2698         if (flags & S_IMMUTABLE)
2699                 ei->i_flags |= EXT4_IMMUTABLE_FL;
2700         if (flags & S_NOATIME)
2701                 ei->i_flags |= EXT4_NOATIME_FL;
2702         if (flags & S_DIRSYNC)
2703                 ei->i_flags |= EXT4_DIRSYNC_FL;
2704 }
2705 static blkcnt_t ext4_inode_blocks(struct ext4_inode *raw_inode,
2706                                         struct ext4_inode_info *ei)
2707 {
2708         blkcnt_t i_blocks ;
2709         struct inode *inode = &(ei->vfs_inode);
2710         struct super_block *sb = inode->i_sb;
2711
2712         if (EXT4_HAS_RO_COMPAT_FEATURE(sb,
2713                                 EXT4_FEATURE_RO_COMPAT_HUGE_FILE)) {
2714                 /* we are using combined 48 bit field */
2715                 i_blocks = ((u64)le16_to_cpu(raw_inode->i_blocks_high)) << 32 |
2716                                         le32_to_cpu(raw_inode->i_blocks_lo);
2717                 if (ei->i_flags & EXT4_HUGE_FILE_FL) {
2718                         /* i_blocks represent file system block size */
2719                         return i_blocks  << (inode->i_blkbits - 9);
2720                 } else {
2721                         return i_blocks;
2722                 }
2723         } else {
2724                 return le32_to_cpu(raw_inode->i_blocks_lo);
2725         }
2726 }
2727
2728 struct inode *ext4_iget(struct super_block *sb, unsigned long ino)
2729 {
2730         struct ext4_iloc iloc;
2731         struct ext4_inode *raw_inode;
2732         struct ext4_inode_info *ei;
2733         struct buffer_head *bh;
2734         struct inode *inode;
2735         long ret;
2736         int block;
2737
2738         inode = iget_locked(sb, ino);
2739         if (!inode)
2740                 return ERR_PTR(-ENOMEM);
2741         if (!(inode->i_state & I_NEW))
2742                 return inode;
2743
2744         ei = EXT4_I(inode);
2745 #ifdef CONFIG_EXT4DEV_FS_POSIX_ACL
2746         ei->i_acl = EXT4_ACL_NOT_CACHED;
2747         ei->i_default_acl = EXT4_ACL_NOT_CACHED;
2748 #endif
2749         ei->i_block_alloc_info = NULL;
2750
2751         ret = __ext4_get_inode_loc(inode, &iloc, 0);
2752         if (ret < 0)
2753                 goto bad_inode;
2754         bh = iloc.bh;
2755         raw_inode = ext4_raw_inode(&iloc);
2756         inode->i_mode = le16_to_cpu(raw_inode->i_mode);
2757         inode->i_uid = (uid_t)le16_to_cpu(raw_inode->i_uid_low);
2758         inode->i_gid = (gid_t)le16_to_cpu(raw_inode->i_gid_low);
2759         if(!(test_opt (inode->i_sb, NO_UID32))) {
2760                 inode->i_uid |= le16_to_cpu(raw_inode->i_uid_high) << 16;
2761                 inode->i_gid |= le16_to_cpu(raw_inode->i_gid_high) << 16;
2762         }
2763         inode->i_nlink = le16_to_cpu(raw_inode->i_links_count);
2764
2765         ei->i_state = 0;
2766         ei->i_dir_start_lookup = 0;
2767         ei->i_dtime = le32_to_cpu(raw_inode->i_dtime);
2768         /* We now have enough fields to check if the inode was active or not.
2769          * This is needed because nfsd might try to access dead inodes
2770          * the test is that same one that e2fsck uses
2771          * NeilBrown 1999oct15
2772          */
2773         if (inode->i_nlink == 0) {
2774                 if (inode->i_mode == 0 ||
2775                     !(EXT4_SB(inode->i_sb)->s_mount_state & EXT4_ORPHAN_FS)) {
2776                         /* this inode is deleted */
2777                         brelse (bh);
2778                         ret = -ESTALE;
2779                         goto bad_inode;
2780                 }
2781                 /* The only unlinked inodes we let through here have
2782                  * valid i_mode and are being read by the orphan
2783                  * recovery code: that's fine, we're about to complete
2784                  * the process of deleting those. */
2785         }
2786         ei->i_flags = le32_to_cpu(raw_inode->i_flags);
2787         inode->i_blocks = ext4_inode_blocks(raw_inode, ei);
2788         ei->i_file_acl = le32_to_cpu(raw_inode->i_file_acl_lo);
2789         if (EXT4_SB(inode->i_sb)->s_es->s_creator_os !=
2790             cpu_to_le32(EXT4_OS_HURD)) {
2791                 ei->i_file_acl |=
2792                         ((__u64)le16_to_cpu(raw_inode->i_file_acl_high)) << 32;
2793         }
2794         inode->i_size = ext4_isize(raw_inode);
2795         ei->i_disksize = inode->i_size;
2796         inode->i_generation = le32_to_cpu(raw_inode->i_generation);
2797         ei->i_block_group = iloc.block_group;
2798         /*
2799          * NOTE! The in-memory inode i_data array is in little-endian order
2800          * even on big-endian machines: we do NOT byteswap the block numbers!
2801          */
2802         for (block = 0; block < EXT4_N_BLOCKS; block++)
2803                 ei->i_data[block] = raw_inode->i_block[block];
2804         INIT_LIST_HEAD(&ei->i_orphan);
2805
2806         if (EXT4_INODE_SIZE(inode->i_sb) > EXT4_GOOD_OLD_INODE_SIZE) {
2807                 ei->i_extra_isize = le16_to_cpu(raw_inode->i_extra_isize);
2808                 if (EXT4_GOOD_OLD_INODE_SIZE + ei->i_extra_isize >
2809                     EXT4_INODE_SIZE(inode->i_sb)) {
2810                         brelse (bh);
2811                         ret = -EIO;
2812                         goto bad_inode;
2813                 }
2814                 if (ei->i_extra_isize == 0) {
2815                         /* The extra space is currently unused. Use it. */
2816                         ei->i_extra_isize = sizeof(struct ext4_inode) -
2817                                             EXT4_GOOD_OLD_INODE_SIZE;
2818                 } else {
2819                         __le32 *magic = (void *)raw_inode +
2820                                         EXT4_GOOD_OLD_INODE_SIZE +
2821                                         ei->i_extra_isize;
2822                         if (*magic == cpu_to_le32(EXT4_XATTR_MAGIC))
2823                                  ei->i_state |= EXT4_STATE_XATTR;
2824                 }
2825         } else
2826                 ei->i_extra_isize = 0;
2827
2828         EXT4_INODE_GET_XTIME(i_ctime, inode, raw_inode);
2829         EXT4_INODE_GET_XTIME(i_mtime, inode, raw_inode);
2830         EXT4_INODE_GET_XTIME(i_atime, inode, raw_inode);
2831         EXT4_EINODE_GET_XTIME(i_crtime, ei, raw_inode);
2832
2833         inode->i_version = le32_to_cpu(raw_inode->i_disk_version);
2834         if (EXT4_INODE_SIZE(inode->i_sb) > EXT4_GOOD_OLD_INODE_SIZE) {
2835                 if (EXT4_FITS_IN_INODE(raw_inode, ei, i_version_hi))
2836                         inode->i_version |=
2837                         (__u64)(le32_to_cpu(raw_inode->i_version_hi)) << 32;
2838         }
2839
2840         if (S_ISREG(inode->i_mode)) {
2841                 inode->i_op = &ext4_file_inode_operations;
2842                 inode->i_fop = &ext4_file_operations;
2843                 ext4_set_aops(inode);
2844         } else if (S_ISDIR(inode->i_mode)) {
2845                 inode->i_op = &ext4_dir_inode_operations;
2846                 inode->i_fop = &ext4_dir_operations;
2847         } else if (S_ISLNK(inode->i_mode)) {
2848                 if (ext4_inode_is_fast_symlink(inode))
2849                         inode->i_op = &ext4_fast_symlink_inode_operations;
2850                 else {
2851                         inode->i_op = &ext4_symlink_inode_operations;
2852                         ext4_set_aops(inode);
2853                 }
2854         } else {
2855                 inode->i_op = &ext4_special_inode_operations;
2856                 if (raw_inode->i_block[0])
2857                         init_special_inode(inode, inode->i_mode,
2858                            old_decode_dev(le32_to_cpu(raw_inode->i_block[0])));
2859                 else
2860                         init_special_inode(inode, inode->i_mode,
2861                            new_decode_dev(le32_to_cpu(raw_inode->i_block[1])));
2862         }
2863         brelse (iloc.bh);
2864         ext4_set_inode_flags(inode);
2865         unlock_new_inode(inode);
2866         return inode;
2867
2868 bad_inode:
2869         iget_failed(inode);
2870         return ERR_PTR(ret);
2871 }
2872
2873 static int ext4_inode_blocks_set(handle_t *handle,
2874                                 struct ext4_inode *raw_inode,
2875                                 struct ext4_inode_info *ei)
2876 {
2877         struct inode *inode = &(ei->vfs_inode);
2878         u64 i_blocks = inode->i_blocks;
2879         struct super_block *sb = inode->i_sb;
2880         int err = 0;
2881
2882         if (i_blocks <= ~0U) {
2883                 /*
2884                  * i_blocks can be represnted in a 32 bit variable
2885                  * as multiple of 512 bytes
2886                  */
2887                 raw_inode->i_blocks_lo   = cpu_to_le32(i_blocks);
2888                 raw_inode->i_blocks_high = 0;
2889                 ei->i_flags &= ~EXT4_HUGE_FILE_FL;
2890         } else if (i_blocks <= 0xffffffffffffULL) {
2891                 /*
2892                  * i_blocks can be represented in a 48 bit variable
2893                  * as multiple of 512 bytes
2894                  */
2895                 err = ext4_update_rocompat_feature(handle, sb,
2896                                             EXT4_FEATURE_RO_COMPAT_HUGE_FILE);
2897                 if (err)
2898                         goto  err_out;
2899                 /* i_block is stored in the split  48 bit fields */
2900                 raw_inode->i_blocks_lo   = cpu_to_le32(i_blocks);
2901                 raw_inode->i_blocks_high = cpu_to_le16(i_blocks >> 32);
2902                 ei->i_flags &= ~EXT4_HUGE_FILE_FL;
2903         } else {
2904                 /*
2905                  * i_blocks should be represented in a 48 bit variable
2906                  * as multiple of  file system block size
2907                  */
2908                 err = ext4_update_rocompat_feature(handle, sb,
2909                                             EXT4_FEATURE_RO_COMPAT_HUGE_FILE);
2910                 if (err)
2911                         goto  err_out;
2912                 ei->i_flags |= EXT4_HUGE_FILE_FL;
2913                 /* i_block is stored in file system block size */
2914                 i_blocks = i_blocks >> (inode->i_blkbits - 9);
2915                 raw_inode->i_blocks_lo   = cpu_to_le32(i_blocks);
2916                 raw_inode->i_blocks_high = cpu_to_le16(i_blocks >> 32);
2917         }
2918 err_out:
2919         return err;
2920 }
2921
2922 /*
2923  * Post the struct inode info into an on-disk inode location in the
2924  * buffer-cache.  This gobbles the caller's reference to the
2925  * buffer_head in the inode location struct.
2926  *
2927  * The caller must have write access to iloc->bh.
2928  */
2929 static int ext4_do_update_inode(handle_t *handle,
2930                                 struct inode *inode,
2931                                 struct ext4_iloc *iloc)
2932 {
2933         struct ext4_inode *raw_inode = ext4_raw_inode(iloc);
2934         struct ext4_inode_info *ei = EXT4_I(inode);
2935         struct buffer_head *bh = iloc->bh;
2936         int err = 0, rc, block;
2937
2938         /* For fields not not tracking in the in-memory inode,
2939          * initialise them to zero for new inodes. */
2940         if (ei->i_state & EXT4_STATE_NEW)
2941                 memset(raw_inode, 0, EXT4_SB(inode->i_sb)->s_inode_size);
2942
2943         ext4_get_inode_flags(ei);
2944         raw_inode->i_mode = cpu_to_le16(inode->i_mode);
2945         if(!(test_opt(inode->i_sb, NO_UID32))) {
2946                 raw_inode->i_uid_low = cpu_to_le16(low_16_bits(inode->i_uid));
2947                 raw_inode->i_gid_low = cpu_to_le16(low_16_bits(inode->i_gid));
2948 /*
2949  * Fix up interoperability with old kernels. Otherwise, old inodes get
2950  * re-used with the upper 16 bits of the uid/gid intact
2951  */
2952                 if(!ei->i_dtime) {
2953                         raw_inode->i_uid_high =
2954                                 cpu_to_le16(high_16_bits(inode->i_uid));
2955                         raw_inode->i_gid_high =
2956                                 cpu_to_le16(high_16_bits(inode->i_gid));
2957                 } else {
2958                         raw_inode->i_uid_high = 0;
2959                         raw_inode->i_gid_high = 0;
2960                 }
2961         } else {
2962                 raw_inode->i_uid_low =
2963                         cpu_to_le16(fs_high2lowuid(inode->i_uid));
2964                 raw_inode->i_gid_low =
2965                         cpu_to_le16(fs_high2lowgid(inode->i_gid));
2966                 raw_inode->i_uid_high = 0;
2967                 raw_inode->i_gid_high = 0;
2968         }
2969         raw_inode->i_links_count = cpu_to_le16(inode->i_nlink);
2970
2971         EXT4_INODE_SET_XTIME(i_ctime, inode, raw_inode);
2972         EXT4_INODE_SET_XTIME(i_mtime, inode, raw_inode);
2973         EXT4_INODE_SET_XTIME(i_atime, inode, raw_inode);
2974         EXT4_EINODE_SET_XTIME(i_crtime, ei, raw_inode);
2975
2976         if (ext4_inode_blocks_set(handle, raw_inode, ei))
2977                 goto out_brelse;
2978         raw_inode->i_dtime = cpu_to_le32(ei->i_dtime);
2979         raw_inode->i_flags = cpu_to_le32(ei->i_flags);
2980         if (EXT4_SB(inode->i_sb)->s_es->s_creator_os !=
2981             cpu_to_le32(EXT4_OS_HURD))
2982                 raw_inode->i_file_acl_high =
2983                         cpu_to_le16(ei->i_file_acl >> 32);
2984         raw_inode->i_file_acl_lo = cpu_to_le32(ei->i_file_acl);
2985         ext4_isize_set(raw_inode, ei->i_disksize);
2986         if (ei->i_disksize > 0x7fffffffULL) {
2987                 struct super_block *sb = inode->i_sb;
2988                 if (!EXT4_HAS_RO_COMPAT_FEATURE(sb,
2989                                 EXT4_FEATURE_RO_COMPAT_LARGE_FILE) ||
2990                                 EXT4_SB(sb)->s_es->s_rev_level ==
2991                                 cpu_to_le32(EXT4_GOOD_OLD_REV)) {
2992                         /* If this is the first large file
2993                          * created, add a flag to the superblock.
2994                          */
2995                         err = ext4_journal_get_write_access(handle,
2996                                         EXT4_SB(sb)->s_sbh);
2997                         if (err)
2998                                 goto out_brelse;
2999                         ext4_update_dynamic_rev(sb);
3000                         EXT4_SET_RO_COMPAT_FEATURE(sb,
3001                                         EXT4_FEATURE_RO_COMPAT_LARGE_FILE);
3002                         sb->s_dirt = 1;
3003                         handle->h_sync = 1;
3004                         err = ext4_journal_dirty_metadata(handle,
3005                                         EXT4_SB(sb)->s_sbh);
3006                 }
3007         }
3008         raw_inode->i_generation = cpu_to_le32(inode->i_generation);
3009         if (S_ISCHR(inode->i_mode) || S_ISBLK(inode->i_mode)) {
3010                 if (old_valid_dev(inode->i_rdev)) {
3011                         raw_inode->i_block[0] =
3012                                 cpu_to_le32(old_encode_dev(inode->i_rdev));
3013                         raw_inode->i_block[1] = 0;
3014                 } else {
3015                         raw_inode->i_block[0] = 0;
3016                         raw_inode->i_block[1] =
3017                                 cpu_to_le32(new_encode_dev(inode->i_rdev));
3018                         raw_inode->i_block[2] = 0;
3019                 }
3020         } else for (block = 0; block < EXT4_N_BLOCKS; block++)
3021                 raw_inode->i_block[block] = ei->i_data[block];
3022
3023         raw_inode->i_disk_version = cpu_to_le32(inode->i_version);
3024         if (ei->i_extra_isize) {
3025                 if (EXT4_FITS_IN_INODE(raw_inode, ei, i_version_hi))
3026                         raw_inode->i_version_hi =
3027                         cpu_to_le32(inode->i_version >> 32);
3028                 raw_inode->i_extra_isize = cpu_to_le16(ei->i_extra_isize);
3029         }
3030
3031
3032         BUFFER_TRACE(bh, "call ext4_journal_dirty_metadata");
3033         rc = ext4_journal_dirty_metadata(handle, bh);
3034         if (!err)
3035                 err = rc;
3036         ei->i_state &= ~EXT4_STATE_NEW;
3037
3038 out_brelse:
3039         brelse (bh);
3040         ext4_std_error(inode->i_sb, err);
3041         return err;
3042 }
3043
3044 /*
3045  * ext4_write_inode()
3046  *
3047  * We are called from a few places:
3048  *
3049  * - Within generic_file_write() for O_SYNC files.
3050  *   Here, there will be no transaction running. We wait for any running
3051  *   trasnaction to commit.
3052  *
3053  * - Within sys_sync(), kupdate and such.
3054  *   We wait on commit, if tol to.
3055  *
3056  * - Within prune_icache() (PF_MEMALLOC == true)
3057  *   Here we simply return.  We can't afford to block kswapd on the
3058  *   journal commit.
3059  *
3060  * In all cases it is actually safe for us to return without doing anything,
3061  * because the inode has been copied into a raw inode buffer in
3062  * ext4_mark_inode_dirty().  This is a correctness thing for O_SYNC and for
3063  * knfsd.
3064  *
3065  * Note that we are absolutely dependent upon all inode dirtiers doing the
3066  * right thing: they *must* call mark_inode_dirty() after dirtying info in
3067  * which we are interested.
3068  *
3069  * It would be a bug for them to not do this.  The code:
3070  *
3071  *      mark_inode_dirty(inode)
3072  *      stuff();
3073  *      inode->i_size = expr;
3074  *
3075  * is in error because a kswapd-driven write_inode() could occur while
3076  * `stuff()' is running, and the new i_size will be lost.  Plus the inode
3077  * will no longer be on the superblock's dirty inode list.
3078  */
3079 int ext4_write_inode(struct inode *inode, int wait)
3080 {
3081         if (current->flags & PF_MEMALLOC)
3082                 return 0;
3083
3084         if (ext4_journal_current_handle()) {
3085                 jbd_debug(1, "called recursively, non-PF_MEMALLOC!\n");
3086                 dump_stack();
3087                 return -EIO;
3088         }
3089
3090         if (!wait)
3091                 return 0;
3092
3093         return ext4_force_commit(inode->i_sb);
3094 }
3095
3096 /*
3097  * ext4_setattr()
3098  *
3099  * Called from notify_change.
3100  *
3101  * We want to trap VFS attempts to truncate the file as soon as
3102  * possible.  In particular, we want to make sure that when the VFS
3103  * shrinks i_size, we put the inode on the orphan list and modify
3104  * i_disksize immediately, so that during the subsequent flushing of
3105  * dirty pages and freeing of disk blocks, we can guarantee that any
3106  * commit will leave the blocks being flushed in an unused state on
3107  * disk.  (On recovery, the inode will get truncated and the blocks will
3108  * be freed, so we have a strong guarantee that no future commit will
3109  * leave these blocks visible to the user.)
3110  *
3111  * Called with inode->sem down.
3112  */
3113 int ext4_setattr(struct dentry *dentry, struct iattr *attr)
3114 {
3115         struct inode *inode = dentry->d_inode;
3116         int error, rc = 0;
3117         const unsigned int ia_valid = attr->ia_valid;
3118
3119         error = inode_change_ok(inode, attr);
3120         if (error)
3121                 return error;
3122
3123         if ((ia_valid & ATTR_UID && attr->ia_uid != inode->i_uid) ||
3124                 (ia_valid & ATTR_GID && attr->ia_gid != inode->i_gid)) {
3125                 handle_t *handle;
3126
3127                 /* (user+group)*(old+new) structure, inode write (sb,
3128                  * inode block, ? - but truncate inode update has it) */
3129                 handle = ext4_journal_start(inode, 2*(EXT4_QUOTA_INIT_BLOCKS(inode->i_sb)+
3130                                         EXT4_QUOTA_DEL_BLOCKS(inode->i_sb))+3);
3131                 if (IS_ERR(handle)) {
3132                         error = PTR_ERR(handle);
3133                         goto err_out;
3134                 }
3135                 error = DQUOT_TRANSFER(inode, attr) ? -EDQUOT : 0;
3136                 if (error) {
3137                         ext4_journal_stop(handle);
3138                         return error;
3139                 }
3140                 /* Update corresponding info in inode so that everything is in
3141                  * one transaction */
3142                 if (attr->ia_valid & ATTR_UID)
3143                         inode->i_uid = attr->ia_uid;
3144                 if (attr->ia_valid & ATTR_GID)
3145                         inode->i_gid = attr->ia_gid;
3146                 error = ext4_mark_inode_dirty(handle, inode);
3147                 ext4_journal_stop(handle);
3148         }
3149
3150         if (attr->ia_valid & ATTR_SIZE) {
3151                 if (!(EXT4_I(inode)->i_flags & EXT4_EXTENTS_FL)) {
3152                         struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
3153
3154                         if (attr->ia_size > sbi->s_bitmap_maxbytes) {
3155                                 error = -EFBIG;
3156                                 goto err_out;
3157                         }
3158                 }
3159         }
3160
3161         if (S_ISREG(inode->i_mode) &&
3162             attr->ia_valid & ATTR_SIZE && attr->ia_size < inode->i_size) {
3163                 handle_t *handle;
3164
3165                 handle = ext4_journal_start(inode, 3);
3166                 if (IS_ERR(handle)) {
3167                         error = PTR_ERR(handle);
3168                         goto err_out;
3169                 }
3170
3171                 error = ext4_orphan_add(handle, inode);
3172                 EXT4_I(inode)->i_disksize = attr->ia_size;
3173                 rc = ext4_mark_inode_dirty(handle, inode);
3174                 if (!error)
3175                         error = rc;
3176                 ext4_journal_stop(handle);
3177         }
3178
3179         rc = inode_setattr(inode, attr);
3180
3181         /* If inode_setattr's call to ext4_truncate failed to get a
3182          * transaction handle at all, we need to clean up the in-core
3183          * orphan list manually. */
3184         if (inode->i_nlink)
3185                 ext4_orphan_del(NULL, inode);
3186
3187         if (!rc && (ia_valid & ATTR_MODE))
3188                 rc = ext4_acl_chmod(inode);
3189
3190 err_out:
3191         ext4_std_error(inode->i_sb, error);
3192         if (!error)
3193                 error = rc;
3194         return error;
3195 }
3196
3197
3198 /*
3199  * How many blocks doth make a writepage()?
3200  *
3201  * With N blocks per page, it may be:
3202  * N data blocks
3203  * 2 indirect block
3204  * 2 dindirect
3205  * 1 tindirect
3206  * N+5 bitmap blocks (from the above)
3207  * N+5 group descriptor summary blocks
3208  * 1 inode block
3209  * 1 superblock.
3210  * 2 * EXT4_SINGLEDATA_TRANS_BLOCKS for the quote files
3211  *
3212  * 3 * (N + 5) + 2 + 2 * EXT4_SINGLEDATA_TRANS_BLOCKS
3213  *
3214  * With ordered or writeback data it's the same, less the N data blocks.
3215  *
3216  * If the inode's direct blocks can hold an integral number of pages then a
3217  * page cannot straddle two indirect blocks, and we can only touch one indirect
3218  * and dindirect block, and the "5" above becomes "3".
3219  *
3220  * This still overestimates under most circumstances.  If we were to pass the
3221  * start and end offsets in here as well we could do block_to_path() on each
3222  * block and work out the exact number of indirects which are touched.  Pah.
3223  */
3224
3225 int ext4_writepage_trans_blocks(struct inode *inode)
3226 {
3227         int bpp = ext4_journal_blocks_per_page(inode);
3228         int indirects = (EXT4_NDIR_BLOCKS % bpp) ? 5 : 3;
3229         int ret;
3230
3231         if (EXT4_I(inode)->i_flags & EXT4_EXTENTS_FL)
3232                 return ext4_ext_writepage_trans_blocks(inode, bpp);
3233
3234         if (ext4_should_journal_data(inode))
3235                 ret = 3 * (bpp + indirects) + 2;
3236         else
3237                 ret = 2 * (bpp + indirects) + 2;
3238
3239 #ifdef CONFIG_QUOTA
3240         /* We know that structure was already allocated during DQUOT_INIT so
3241          * we will be updating only the data blocks + inodes */
3242         ret += 2*EXT4_QUOTA_TRANS_BLOCKS(inode->i_sb);
3243 #endif
3244
3245         return ret;
3246 }
3247
3248 /*
3249  * The caller must have previously called ext4_reserve_inode_write().
3250  * Give this, we know that the caller already has write access to iloc->bh.
3251  */
3252 int ext4_mark_iloc_dirty(handle_t *handle,
3253                 struct inode *inode, struct ext4_iloc *iloc)
3254 {
3255         int err = 0;
3256
3257         if (test_opt(inode->i_sb, I_VERSION))
3258                 inode_inc_iversion(inode);
3259
3260         /* the do_update_inode consumes one bh->b_count */
3261         get_bh(iloc->bh);
3262
3263         /* ext4_do_update_inode() does jbd2_journal_dirty_metadata */
3264         err = ext4_do_update_inode(handle, inode, iloc);
3265         put_bh(iloc->bh);
3266         return err;
3267 }
3268
3269 /*
3270  * On success, We end up with an outstanding reference count against
3271  * iloc->bh.  This _must_ be cleaned up later.
3272  */
3273
3274 int
3275 ext4_reserve_inode_write(handle_t *handle, struct inode *inode,
3276                          struct ext4_iloc *iloc)
3277 {
3278         int err = 0;
3279         if (handle) {
3280                 err = ext4_get_inode_loc(inode, iloc);
3281                 if (!err) {
3282                         BUFFER_TRACE(iloc->bh, "get_write_access");
3283                         err = ext4_journal_get_write_access(handle, iloc->bh);
3284                         if (err) {
3285                                 brelse(iloc->bh);
3286                                 iloc->bh = NULL;
3287                         }
3288                 }
3289         }
3290         ext4_std_error(inode->i_sb, err);
3291         return err;
3292 }
3293
3294 /*
3295  * Expand an inode by new_extra_isize bytes.
3296  * Returns 0 on success or negative error number on failure.
3297  */
3298 static int ext4_expand_extra_isize(struct inode *inode,
3299                                    unsigned int new_extra_isize,
3300                                    struct ext4_iloc iloc,
3301                                    handle_t *handle)
3302 {
3303         struct ext4_inode *raw_inode;
3304         struct ext4_xattr_ibody_header *header;
3305         struct ext4_xattr_entry *entry;
3306
3307         if (EXT4_I(inode)->i_extra_isize >= new_extra_isize)
3308                 return 0;
3309
3310         raw_inode = ext4_raw_inode(&iloc);
3311
3312         header = IHDR(inode, raw_inode);
3313         entry = IFIRST(header);
3314
3315         /* No extended attributes present */
3316         if (!(EXT4_I(inode)->i_state & EXT4_STATE_XATTR) ||
3317                 header->h_magic != cpu_to_le32(EXT4_XATTR_MAGIC)) {
3318                 memset((void *)raw_inode + EXT4_GOOD_OLD_INODE_SIZE, 0,
3319                         new_extra_isize);
3320                 EXT4_I(inode)->i_extra_isize = new_extra_isize;
3321                 return 0;
3322         }
3323
3324         /* try to expand with EAs present */
3325         return ext4_expand_extra_isize_ea(inode, new_extra_isize,
3326                                           raw_inode, handle);
3327 }
3328
3329 /*
3330  * What we do here is to mark the in-core inode as clean with respect to inode
3331  * dirtiness (it may still be data-dirty).
3332  * This means that the in-core inode may be reaped by prune_icache
3333  * without having to perform any I/O.  This is a very good thing,
3334  * because *any* task may call prune_icache - even ones which
3335  * have a transaction open against a different journal.
3336  *
3337  * Is this cheating?  Not really.  Sure, we haven't written the
3338  * inode out, but prune_icache isn't a user-visible syncing function.
3339  * Whenever the user wants stuff synced (sys_sync, sys_msync, sys_fsync)
3340  * we start and wait on commits.
3341  *
3342  * Is this efficient/effective?  Well, we're being nice to the system
3343  * by cleaning up our inodes proactively so they can be reaped
3344  * without I/O.  But we are potentially leaving up to five seconds'
3345  * worth of inodes floating about which prune_icache wants us to
3346  * write out.  One way to fix that would be to get prune_icache()
3347  * to do a write_super() to free up some memory.  It has the desired
3348  * effect.
3349  */
3350 int ext4_mark_inode_dirty(handle_t *handle, struct inode *inode)
3351 {
3352         struct ext4_iloc iloc;
3353         struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
3354         static unsigned int mnt_count;
3355         int err, ret;
3356
3357         might_sleep();
3358         err = ext4_reserve_inode_write(handle, inode, &iloc);
3359         if (EXT4_I(inode)->i_extra_isize < sbi->s_want_extra_isize &&
3360             !(EXT4_I(inode)->i_state & EXT4_STATE_NO_EXPAND)) {
3361                 /*
3362                  * We need extra buffer credits since we may write into EA block
3363                  * with this same handle. If journal_extend fails, then it will
3364                  * only result in a minor loss of functionality for that inode.
3365                  * If this is felt to be critical, then e2fsck should be run to
3366                  * force a large enough s_min_extra_isize.
3367                  */
3368                 if ((jbd2_journal_extend(handle,
3369                              EXT4_DATA_TRANS_BLOCKS(inode->i_sb))) == 0) {
3370                         ret = ext4_expand_extra_isize(inode,
3371                                                       sbi->s_want_extra_isize,
3372                                                       iloc, handle);
3373                         if (ret) {
3374                                 EXT4_I(inode)->i_state |= EXT4_STATE_NO_EXPAND;
3375                                 if (mnt_count !=
3376                                         le16_to_cpu(sbi->s_es->s_mnt_count)) {
3377                                         ext4_warning(inode->i_sb, __FUNCTION__,
3378                                         "Unable to expand inode %lu. Delete"
3379                                         " some EAs or run e2fsck.",
3380                                         inode->i_ino);
3381                                         mnt_count =
3382                                           le16_to_cpu(sbi->s_es->s_mnt_count);
3383                                 }
3384                         }
3385                 }
3386         }
3387         if (!err)
3388                 err = ext4_mark_iloc_dirty(handle, inode, &iloc);
3389         return err;
3390 }
3391
3392 /*
3393  * ext4_dirty_inode() is called from __mark_inode_dirty()
3394  *
3395  * We're really interested in the case where a file is being extended.
3396  * i_size has been changed by generic_commit_write() and we thus need
3397  * to include the updated inode in the current transaction.
3398  *
3399  * Also, DQUOT_ALLOC_SPACE() will always dirty the inode when blocks
3400  * are allocated to the file.
3401  *
3402  * If the inode is marked synchronous, we don't honour that here - doing
3403  * so would cause a commit on atime updates, which we don't bother doing.
3404  * We handle synchronous inodes at the highest possible level.
3405  */
3406 void ext4_dirty_inode(struct inode *inode)
3407 {
3408         handle_t *current_handle = ext4_journal_current_handle();
3409         handle_t *handle;
3410
3411         handle = ext4_journal_start(inode, 2);
3412         if (IS_ERR(handle))
3413                 goto out;
3414         if (current_handle &&
3415                 current_handle->h_transaction != handle->h_transaction) {
3416                 /* This task has a transaction open against a different fs */
3417                 printk(KERN_EMERG "%s: transactions do not match!\n",
3418                        __FUNCTION__);
3419         } else {
3420                 jbd_debug(5, "marking dirty.  outer handle=%p\n",
3421                                 current_handle);
3422                 ext4_mark_inode_dirty(handle, inode);
3423         }
3424         ext4_journal_stop(handle);
3425 out:
3426         return;
3427 }
3428
3429 #if 0
3430 /*
3431  * Bind an inode's backing buffer_head into this transaction, to prevent
3432  * it from being flushed to disk early.  Unlike
3433  * ext4_reserve_inode_write, this leaves behind no bh reference and
3434  * returns no iloc structure, so the caller needs to repeat the iloc
3435  * lookup to mark the inode dirty later.
3436  */
3437 static int ext4_pin_inode(handle_t *handle, struct inode *inode)
3438 {
3439         struct ext4_iloc iloc;
3440
3441         int err = 0;
3442         if (handle) {
3443                 err = ext4_get_inode_loc(inode, &iloc);
3444                 if (!err) {
3445                         BUFFER_TRACE(iloc.bh, "get_write_access");
3446                         err = jbd2_journal_get_write_access(handle, iloc.bh);
3447                         if (!err)
3448                                 err = ext4_journal_dirty_metadata(handle,
3449                                                                   iloc.bh);
3450                         brelse(iloc.bh);
3451                 }
3452         }
3453         ext4_std_error(inode->i_sb, err);
3454         return err;
3455 }
3456 #endif
3457
3458 int ext4_change_inode_journal_flag(struct inode *inode, int val)
3459 {
3460         journal_t *journal;
3461         handle_t *handle;
3462         int err;
3463
3464         /*
3465          * We have to be very careful here: changing a data block's
3466          * journaling status dynamically is dangerous.  If we write a
3467          * data block to the journal, change the status and then delete
3468          * that block, we risk forgetting to revoke the old log record
3469          * from the journal and so a subsequent replay can corrupt data.
3470          * So, first we make sure that the journal is empty and that
3471          * nobody is changing anything.
3472          */
3473
3474         journal = EXT4_JOURNAL(inode);
3475         if (is_journal_aborted(journal))
3476                 return -EROFS;
3477
3478         jbd2_journal_lock_updates(journal);
3479         jbd2_journal_flush(journal);
3480
3481         /*
3482          * OK, there are no updates running now, and all cached data is
3483          * synced to disk.  We are now in a completely consistent state
3484          * which doesn't have anything in the journal, and we know that
3485          * no filesystem updates are running, so it is safe to modify
3486          * the inode's in-core data-journaling state flag now.
3487          */
3488
3489         if (val)
3490                 EXT4_I(inode)->i_flags |= EXT4_JOURNAL_DATA_FL;
3491         else
3492                 EXT4_I(inode)->i_flags &= ~EXT4_JOURNAL_DATA_FL;
3493         ext4_set_aops(inode);
3494
3495         jbd2_journal_unlock_updates(journal);
3496
3497         /* Finally we can mark the inode as dirty. */
3498
3499         handle = ext4_journal_start(inode, 1);
3500         if (IS_ERR(handle))
3501                 return PTR_ERR(handle);
3502
3503         err = ext4_mark_inode_dirty(handle, inode);
3504         handle->h_sync = 1;
3505         ext4_journal_stop(handle);
3506         ext4_std_error(inode->i_sb, err);
3507
3508         return err;
3509 }