[PATCH] ext4 calls journal_stop
[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/smp_lock.h>
31 #include <linux/highuid.h>
32 #include <linux/pagemap.h>
33 #include <linux/quotaops.h>
34 #include <linux/string.h>
35 #include <linux/buffer_head.h>
36 #include <linux/writeback.h>
37 #include <linux/mpage.h>
38 #include <linux/uio.h>
39 #include <linux/bio.h>
40 #include "xattr.h"
41 #include "acl.h"
42
43 /*
44  * Test whether an inode is a fast symlink.
45  */
46 static int ext4_inode_is_fast_symlink(struct inode *inode)
47 {
48         int ea_blocks = EXT4_I(inode)->i_file_acl ?
49                 (inode->i_sb->s_blocksize >> 9) : 0;
50
51         return (S_ISLNK(inode->i_mode) && inode->i_blocks - ea_blocks == 0);
52 }
53
54 /*
55  * The ext4 forget function must perform a revoke if we are freeing data
56  * which has been journaled.  Metadata (eg. indirect blocks) must be
57  * revoked in all cases.
58  *
59  * "bh" may be NULL: a metadata block may have been freed from memory
60  * but there may still be a record of it in the journal, and that record
61  * still needs to be revoked.
62  */
63 int ext4_forget(handle_t *handle, int is_metadata, struct inode *inode,
64                         struct buffer_head *bh, ext4_fsblk_t blocknr)
65 {
66         int err;
67
68         might_sleep();
69
70         BUFFER_TRACE(bh, "enter");
71
72         jbd_debug(4, "forgetting bh %p: is_metadata = %d, mode %o, "
73                   "data mode %lx\n",
74                   bh, is_metadata, inode->i_mode,
75                   test_opt(inode->i_sb, DATA_FLAGS));
76
77         /* Never use the revoke function if we are doing full data
78          * journaling: there is no need to, and a V1 superblock won't
79          * support it.  Otherwise, only skip the revoke on un-journaled
80          * data blocks. */
81
82         if (test_opt(inode->i_sb, DATA_FLAGS) == EXT4_MOUNT_JOURNAL_DATA ||
83             (!is_metadata && !ext4_should_journal_data(inode))) {
84                 if (bh) {
85                         BUFFER_TRACE(bh, "call jbd2_journal_forget");
86                         return ext4_journal_forget(handle, bh);
87                 }
88                 return 0;
89         }
90
91         /*
92          * data!=journal && (is_metadata || should_journal_data(inode))
93          */
94         BUFFER_TRACE(bh, "call ext4_journal_revoke");
95         err = ext4_journal_revoke(handle, blocknr, bh);
96         if (err)
97                 ext4_abort(inode->i_sb, __FUNCTION__,
98                            "error %d when attempting revoke", err);
99         BUFFER_TRACE(bh, "exit");
100         return err;
101 }
102
103 /*
104  * Work out how many blocks we need to proceed with the next chunk of a
105  * truncate transaction.
106  */
107 static unsigned long blocks_for_truncate(struct inode *inode)
108 {
109         unsigned long needed;
110
111         needed = inode->i_blocks >> (inode->i_sb->s_blocksize_bits - 9);
112
113         /* Give ourselves just enough room to cope with inodes in which
114          * i_blocks is corrupt: we've seen disk corruptions in the past
115          * which resulted in random data in an inode which looked enough
116          * like a regular file for ext4 to try to delete it.  Things
117          * will go a bit crazy if that happens, but at least we should
118          * try not to panic the whole kernel. */
119         if (needed < 2)
120                 needed = 2;
121
122         /* But we need to bound the transaction so we don't overflow the
123          * journal. */
124         if (needed > EXT4_MAX_TRANS_DATA)
125                 needed = EXT4_MAX_TRANS_DATA;
126
127         return EXT4_DATA_TRANS_BLOCKS(inode->i_sb) + needed;
128 }
129
130 /*
131  * Truncate transactions can be complex and absolutely huge.  So we need to
132  * be able to restart the transaction at a conventient checkpoint to make
133  * sure we don't overflow the journal.
134  *
135  * start_transaction gets us a new handle for a truncate transaction,
136  * and extend_transaction tries to extend the existing one a bit.  If
137  * extend fails, we need to propagate the failure up and restart the
138  * transaction in the top-level truncate loop. --sct
139  */
140 static handle_t *start_transaction(struct inode *inode)
141 {
142         handle_t *result;
143
144         result = ext4_journal_start(inode, blocks_for_truncate(inode));
145         if (!IS_ERR(result))
146                 return result;
147
148         ext4_std_error(inode->i_sb, PTR_ERR(result));
149         return result;
150 }
151
152 /*
153  * Try to extend this transaction for the purposes of truncation.
154  *
155  * Returns 0 if we managed to create more room.  If we can't create more
156  * room, and the transaction must be restarted we return 1.
157  */
158 static int try_to_extend_transaction(handle_t *handle, struct inode *inode)
159 {
160         if (handle->h_buffer_credits > EXT4_RESERVE_TRANS_BLOCKS)
161                 return 0;
162         if (!ext4_journal_extend(handle, blocks_for_truncate(inode)))
163                 return 0;
164         return 1;
165 }
166
167 /*
168  * Restart the transaction associated with *handle.  This does a commit,
169  * so before we call here everything must be consistently dirtied against
170  * this transaction.
171  */
172 static int ext4_journal_test_restart(handle_t *handle, struct inode *inode)
173 {
174         jbd_debug(2, "restarting handle %p\n", handle);
175         return ext4_journal_restart(handle, blocks_for_truncate(inode));
176 }
177
178 /*
179  * Called at the last iput() if i_nlink is zero.
180  */
181 void ext4_delete_inode (struct inode * inode)
182 {
183         handle_t *handle;
184
185         truncate_inode_pages(&inode->i_data, 0);
186
187         if (is_bad_inode(inode))
188                 goto no_delete;
189
190         handle = start_transaction(inode);
191         if (IS_ERR(handle)) {
192                 /*
193                  * If we're going to skip the normal cleanup, we still need to
194                  * make sure that the in-core orphan linked list is properly
195                  * cleaned up.
196                  */
197                 ext4_orphan_del(NULL, inode);
198                 goto no_delete;
199         }
200
201         if (IS_SYNC(inode))
202                 handle->h_sync = 1;
203         inode->i_size = 0;
204         if (inode->i_blocks)
205                 ext4_truncate(inode);
206         /*
207          * Kill off the orphan record which ext4_truncate created.
208          * AKPM: I think this can be inside the above `if'.
209          * Note that ext4_orphan_del() has to be able to cope with the
210          * deletion of a non-existent orphan - this is because we don't
211          * know if ext4_truncate() actually created an orphan record.
212          * (Well, we could do this if we need to, but heck - it works)
213          */
214         ext4_orphan_del(handle, inode);
215         EXT4_I(inode)->i_dtime  = get_seconds();
216
217         /*
218          * One subtle ordering requirement: if anything has gone wrong
219          * (transaction abort, IO errors, whatever), then we can still
220          * do these next steps (the fs will already have been marked as
221          * having errors), but we can't free the inode if the mark_dirty
222          * fails.
223          */
224         if (ext4_mark_inode_dirty(handle, inode))
225                 /* If that failed, just do the required in-core inode clear. */
226                 clear_inode(inode);
227         else
228                 ext4_free_inode(handle, inode);
229         ext4_journal_stop(handle);
230         return;
231 no_delete:
232         clear_inode(inode);     /* We must guarantee clearing of inode... */
233 }
234
235 typedef struct {
236         __le32  *p;
237         __le32  key;
238         struct buffer_head *bh;
239 } Indirect;
240
241 static inline void add_chain(Indirect *p, struct buffer_head *bh, __le32 *v)
242 {
243         p->key = *(p->p = v);
244         p->bh = bh;
245 }
246
247 static int verify_chain(Indirect *from, Indirect *to)
248 {
249         while (from <= to && from->key == *from->p)
250                 from++;
251         return (from > to);
252 }
253
254 /**
255  *      ext4_block_to_path - parse the block number into array of offsets
256  *      @inode: inode in question (we are only interested in its superblock)
257  *      @i_block: block number to be parsed
258  *      @offsets: array to store the offsets in
259  *      @boundary: set this non-zero if the referred-to block is likely to be
260  *             followed (on disk) by an indirect block.
261  *
262  *      To store the locations of file's data ext4 uses a data structure common
263  *      for UNIX filesystems - tree of pointers anchored in the inode, with
264  *      data blocks at leaves and indirect blocks in intermediate nodes.
265  *      This function translates the block number into path in that tree -
266  *      return value is the path length and @offsets[n] is the offset of
267  *      pointer to (n+1)th node in the nth one. If @block is out of range
268  *      (negative or too large) warning is printed and zero returned.
269  *
270  *      Note: function doesn't find node addresses, so no IO is needed. All
271  *      we need to know is the capacity of indirect blocks (taken from the
272  *      inode->i_sb).
273  */
274
275 /*
276  * Portability note: the last comparison (check that we fit into triple
277  * indirect block) is spelled differently, because otherwise on an
278  * architecture with 32-bit longs and 8Kb pages we might get into trouble
279  * if our filesystem had 8Kb blocks. We might use long long, but that would
280  * kill us on x86. Oh, well, at least the sign propagation does not matter -
281  * i_block would have to be negative in the very beginning, so we would not
282  * get there at all.
283  */
284
285 static int ext4_block_to_path(struct inode *inode,
286                         long i_block, int offsets[4], int *boundary)
287 {
288         int ptrs = EXT4_ADDR_PER_BLOCK(inode->i_sb);
289         int ptrs_bits = EXT4_ADDR_PER_BLOCK_BITS(inode->i_sb);
290         const long direct_blocks = EXT4_NDIR_BLOCKS,
291                 indirect_blocks = ptrs,
292                 double_blocks = (1 << (ptrs_bits * 2));
293         int n = 0;
294         int final = 0;
295
296         if (i_block < 0) {
297                 ext4_warning (inode->i_sb, "ext4_block_to_path", "block < 0");
298         } else if (i_block < direct_blocks) {
299                 offsets[n++] = i_block;
300                 final = direct_blocks;
301         } else if ( (i_block -= direct_blocks) < indirect_blocks) {
302                 offsets[n++] = EXT4_IND_BLOCK;
303                 offsets[n++] = i_block;
304                 final = ptrs;
305         } else if ((i_block -= indirect_blocks) < double_blocks) {
306                 offsets[n++] = EXT4_DIND_BLOCK;
307                 offsets[n++] = i_block >> ptrs_bits;
308                 offsets[n++] = i_block & (ptrs - 1);
309                 final = ptrs;
310         } else if (((i_block -= double_blocks) >> (ptrs_bits * 2)) < ptrs) {
311                 offsets[n++] = EXT4_TIND_BLOCK;
312                 offsets[n++] = i_block >> (ptrs_bits * 2);
313                 offsets[n++] = (i_block >> ptrs_bits) & (ptrs - 1);
314                 offsets[n++] = i_block & (ptrs - 1);
315                 final = ptrs;
316         } else {
317                 ext4_warning(inode->i_sb, "ext4_block_to_path", "block > big");
318         }
319         if (boundary)
320                 *boundary = final - 1 - (i_block & (ptrs - 1));
321         return n;
322 }
323
324 /**
325  *      ext4_get_branch - read the chain of indirect blocks leading to data
326  *      @inode: inode in question
327  *      @depth: depth of the chain (1 - direct pointer, etc.)
328  *      @offsets: offsets of pointers in inode/indirect blocks
329  *      @chain: place to store the result
330  *      @err: here we store the error value
331  *
332  *      Function fills the array of triples <key, p, bh> and returns %NULL
333  *      if everything went OK or the pointer to the last filled triple
334  *      (incomplete one) otherwise. Upon the return chain[i].key contains
335  *      the number of (i+1)-th block in the chain (as it is stored in memory,
336  *      i.e. little-endian 32-bit), chain[i].p contains the address of that
337  *      number (it points into struct inode for i==0 and into the bh->b_data
338  *      for i>0) and chain[i].bh points to the buffer_head of i-th indirect
339  *      block for i>0 and NULL for i==0. In other words, it holds the block
340  *      numbers of the chain, addresses they were taken from (and where we can
341  *      verify that chain did not change) and buffer_heads hosting these
342  *      numbers.
343  *
344  *      Function stops when it stumbles upon zero pointer (absent block)
345  *              (pointer to last triple returned, *@err == 0)
346  *      or when it gets an IO error reading an indirect block
347  *              (ditto, *@err == -EIO)
348  *      or when it notices that chain had been changed while it was reading
349  *              (ditto, *@err == -EAGAIN)
350  *      or when it reads all @depth-1 indirect blocks successfully and finds
351  *      the whole chain, all way to the data (returns %NULL, *err == 0).
352  */
353 static Indirect *ext4_get_branch(struct inode *inode, int depth, int *offsets,
354                                  Indirect chain[4], int *err)
355 {
356         struct super_block *sb = inode->i_sb;
357         Indirect *p = chain;
358         struct buffer_head *bh;
359
360         *err = 0;
361         /* i_data is not going away, no lock needed */
362         add_chain (chain, NULL, EXT4_I(inode)->i_data + *offsets);
363         if (!p->key)
364                 goto no_block;
365         while (--depth) {
366                 bh = sb_bread(sb, le32_to_cpu(p->key));
367                 if (!bh)
368                         goto failure;
369                 /* Reader: pointers */
370                 if (!verify_chain(chain, p))
371                         goto changed;
372                 add_chain(++p, bh, (__le32*)bh->b_data + *++offsets);
373                 /* Reader: end */
374                 if (!p->key)
375                         goto no_block;
376         }
377         return NULL;
378
379 changed:
380         brelse(bh);
381         *err = -EAGAIN;
382         goto no_block;
383 failure:
384         *err = -EIO;
385 no_block:
386         return p;
387 }
388
389 /**
390  *      ext4_find_near - find a place for allocation with sufficient locality
391  *      @inode: owner
392  *      @ind: descriptor of indirect block.
393  *
394  *      This function returns the prefered place for block allocation.
395  *      It is used when heuristic for sequential allocation fails.
396  *      Rules are:
397  *        + if there is a block to the left of our position - allocate near it.
398  *        + if pointer will live in indirect block - allocate near that block.
399  *        + if pointer will live in inode - allocate in the same
400  *          cylinder group.
401  *
402  * In the latter case we colour the starting block by the callers PID to
403  * prevent it from clashing with concurrent allocations for a different inode
404  * in the same block group.   The PID is used here so that functionally related
405  * files will be close-by on-disk.
406  *
407  *      Caller must make sure that @ind is valid and will stay that way.
408  */
409 static ext4_fsblk_t ext4_find_near(struct inode *inode, Indirect *ind)
410 {
411         struct ext4_inode_info *ei = EXT4_I(inode);
412         __le32 *start = ind->bh ? (__le32*) ind->bh->b_data : ei->i_data;
413         __le32 *p;
414         ext4_fsblk_t bg_start;
415         ext4_grpblk_t colour;
416
417         /* Try to find previous block */
418         for (p = ind->p - 1; p >= start; p--) {
419                 if (*p)
420                         return le32_to_cpu(*p);
421         }
422
423         /* No such thing, so let's try location of indirect block */
424         if (ind->bh)
425                 return ind->bh->b_blocknr;
426
427         /*
428          * It is going to be referred to from the inode itself? OK, just put it
429          * into the same cylinder group then.
430          */
431         bg_start = ext4_group_first_block_no(inode->i_sb, ei->i_block_group);
432         colour = (current->pid % 16) *
433                         (EXT4_BLOCKS_PER_GROUP(inode->i_sb) / 16);
434         return bg_start + colour;
435 }
436
437 /**
438  *      ext4_find_goal - find a prefered place for allocation.
439  *      @inode: owner
440  *      @block:  block we want
441  *      @chain:  chain of indirect blocks
442  *      @partial: pointer to the last triple within a chain
443  *      @goal:  place to store the result.
444  *
445  *      Normally this function find the prefered place for block allocation,
446  *      stores it in *@goal and returns zero.
447  */
448
449 static ext4_fsblk_t ext4_find_goal(struct inode *inode, long block,
450                 Indirect chain[4], Indirect *partial)
451 {
452         struct ext4_block_alloc_info *block_i;
453
454         block_i =  EXT4_I(inode)->i_block_alloc_info;
455
456         /*
457          * try the heuristic for sequential allocation,
458          * failing that at least try to get decent locality.
459          */
460         if (block_i && (block == block_i->last_alloc_logical_block + 1)
461                 && (block_i->last_alloc_physical_block != 0)) {
462                 return block_i->last_alloc_physical_block + 1;
463         }
464
465         return ext4_find_near(inode, partial);
466 }
467
468 /**
469  *      ext4_blks_to_allocate: Look up the block map and count the number
470  *      of direct blocks need to be allocated for the given branch.
471  *
472  *      @branch: chain of indirect blocks
473  *      @k: number of blocks need for indirect blocks
474  *      @blks: number of data blocks to be mapped.
475  *      @blocks_to_boundary:  the offset in the indirect block
476  *
477  *      return the total number of blocks to be allocate, including the
478  *      direct and indirect blocks.
479  */
480 static int ext4_blks_to_allocate(Indirect *branch, int k, unsigned long blks,
481                 int blocks_to_boundary)
482 {
483         unsigned long count = 0;
484
485         /*
486          * Simple case, [t,d]Indirect block(s) has not allocated yet
487          * then it's clear blocks on that path have not allocated
488          */
489         if (k > 0) {
490                 /* right now we don't handle cross boundary allocation */
491                 if (blks < blocks_to_boundary + 1)
492                         count += blks;
493                 else
494                         count += blocks_to_boundary + 1;
495                 return count;
496         }
497
498         count++;
499         while (count < blks && count <= blocks_to_boundary &&
500                 le32_to_cpu(*(branch[0].p + count)) == 0) {
501                 count++;
502         }
503         return count;
504 }
505
506 /**
507  *      ext4_alloc_blocks: multiple allocate blocks needed for a branch
508  *      @indirect_blks: the number of blocks need to allocate for indirect
509  *                      blocks
510  *
511  *      @new_blocks: on return it will store the new block numbers for
512  *      the indirect blocks(if needed) and the first direct block,
513  *      @blks:  on return it will store the total number of allocated
514  *              direct blocks
515  */
516 static int ext4_alloc_blocks(handle_t *handle, struct inode *inode,
517                         ext4_fsblk_t goal, int indirect_blks, int blks,
518                         ext4_fsblk_t new_blocks[4], int *err)
519 {
520         int target, i;
521         unsigned long count = 0;
522         int index = 0;
523         ext4_fsblk_t current_block = 0;
524         int ret = 0;
525
526         /*
527          * Here we try to allocate the requested multiple blocks at once,
528          * on a best-effort basis.
529          * To build a branch, we should allocate blocks for
530          * the indirect blocks(if not allocated yet), and at least
531          * the first direct block of this branch.  That's the
532          * minimum number of blocks need to allocate(required)
533          */
534         target = blks + indirect_blks;
535
536         while (1) {
537                 count = target;
538                 /* allocating blocks for indirect blocks and direct blocks */
539                 current_block = ext4_new_blocks(handle,inode,goal,&count,err);
540                 if (*err)
541                         goto failed_out;
542
543                 target -= count;
544                 /* allocate blocks for indirect blocks */
545                 while (index < indirect_blks && count) {
546                         new_blocks[index++] = current_block++;
547                         count--;
548                 }
549
550                 if (count > 0)
551                         break;
552         }
553
554         /* save the new block number for the first direct block */
555         new_blocks[index] = current_block;
556
557         /* total number of blocks allocated for direct blocks */
558         ret = count;
559         *err = 0;
560         return ret;
561 failed_out:
562         for (i = 0; i <index; i++)
563                 ext4_free_blocks(handle, inode, new_blocks[i], 1);
564         return ret;
565 }
566
567 /**
568  *      ext4_alloc_branch - allocate and set up a chain of blocks.
569  *      @inode: owner
570  *      @indirect_blks: number of allocated indirect blocks
571  *      @blks: number of allocated direct blocks
572  *      @offsets: offsets (in the blocks) to store the pointers to next.
573  *      @branch: place to store the chain in.
574  *
575  *      This function allocates blocks, zeroes out all but the last one,
576  *      links them into chain and (if we are synchronous) writes them to disk.
577  *      In other words, it prepares a branch that can be spliced onto the
578  *      inode. It stores the information about that chain in the branch[], in
579  *      the same format as ext4_get_branch() would do. We are calling it after
580  *      we had read the existing part of chain and partial points to the last
581  *      triple of that (one with zero ->key). Upon the exit we have the same
582  *      picture as after the successful ext4_get_block(), except that in one
583  *      place chain is disconnected - *branch->p is still zero (we did not
584  *      set the last link), but branch->key contains the number that should
585  *      be placed into *branch->p to fill that gap.
586  *
587  *      If allocation fails we free all blocks we've allocated (and forget
588  *      their buffer_heads) and return the error value the from failed
589  *      ext4_alloc_block() (normally -ENOSPC). Otherwise we set the chain
590  *      as described above and return 0.
591  */
592 static int ext4_alloc_branch(handle_t *handle, struct inode *inode,
593                         int indirect_blks, int *blks, ext4_fsblk_t goal,
594                         int *offsets, Indirect *branch)
595 {
596         int blocksize = inode->i_sb->s_blocksize;
597         int i, n = 0;
598         int err = 0;
599         struct buffer_head *bh;
600         int num;
601         ext4_fsblk_t new_blocks[4];
602         ext4_fsblk_t current_block;
603
604         num = ext4_alloc_blocks(handle, inode, goal, indirect_blks,
605                                 *blks, new_blocks, &err);
606         if (err)
607                 return err;
608
609         branch[0].key = cpu_to_le32(new_blocks[0]);
610         /*
611          * metadata blocks and data blocks are allocated.
612          */
613         for (n = 1; n <= indirect_blks;  n++) {
614                 /*
615                  * Get buffer_head for parent block, zero it out
616                  * and set the pointer to new one, then send
617                  * parent to disk.
618                  */
619                 bh = sb_getblk(inode->i_sb, new_blocks[n-1]);
620                 branch[n].bh = bh;
621                 lock_buffer(bh);
622                 BUFFER_TRACE(bh, "call get_create_access");
623                 err = ext4_journal_get_create_access(handle, bh);
624                 if (err) {
625                         unlock_buffer(bh);
626                         brelse(bh);
627                         goto failed;
628                 }
629
630                 memset(bh->b_data, 0, blocksize);
631                 branch[n].p = (__le32 *) bh->b_data + offsets[n];
632                 branch[n].key = cpu_to_le32(new_blocks[n]);
633                 *branch[n].p = branch[n].key;
634                 if ( n == indirect_blks) {
635                         current_block = new_blocks[n];
636                         /*
637                          * End of chain, update the last new metablock of
638                          * the chain to point to the new allocated
639                          * data blocks numbers
640                          */
641                         for (i=1; i < num; i++)
642                                 *(branch[n].p + i) = cpu_to_le32(++current_block);
643                 }
644                 BUFFER_TRACE(bh, "marking uptodate");
645                 set_buffer_uptodate(bh);
646                 unlock_buffer(bh);
647
648                 BUFFER_TRACE(bh, "call ext4_journal_dirty_metadata");
649                 err = ext4_journal_dirty_metadata(handle, bh);
650                 if (err)
651                         goto failed;
652         }
653         *blks = num;
654         return err;
655 failed:
656         /* Allocation failed, free what we already allocated */
657         for (i = 1; i <= n ; i++) {
658                 BUFFER_TRACE(branch[i].bh, "call jbd2_journal_forget");
659                 ext4_journal_forget(handle, branch[i].bh);
660         }
661         for (i = 0; i <indirect_blks; i++)
662                 ext4_free_blocks(handle, inode, new_blocks[i], 1);
663
664         ext4_free_blocks(handle, inode, new_blocks[i], num);
665
666         return err;
667 }
668
669 /**
670  * ext4_splice_branch - splice the allocated branch onto inode.
671  * @inode: owner
672  * @block: (logical) number of block we are adding
673  * @chain: chain of indirect blocks (with a missing link - see
674  *      ext4_alloc_branch)
675  * @where: location of missing link
676  * @num:   number of indirect blocks we are adding
677  * @blks:  number of direct blocks we are adding
678  *
679  * This function fills the missing link and does all housekeeping needed in
680  * inode (->i_blocks, etc.). In case of success we end up with the full
681  * chain to new block and return 0.
682  */
683 static int ext4_splice_branch(handle_t *handle, struct inode *inode,
684                         long block, Indirect *where, int num, int blks)
685 {
686         int i;
687         int err = 0;
688         struct ext4_block_alloc_info *block_i;
689         ext4_fsblk_t current_block;
690
691         block_i = EXT4_I(inode)->i_block_alloc_info;
692         /*
693          * If we're splicing into a [td]indirect block (as opposed to the
694          * inode) then we need to get write access to the [td]indirect block
695          * before the splice.
696          */
697         if (where->bh) {
698                 BUFFER_TRACE(where->bh, "get_write_access");
699                 err = ext4_journal_get_write_access(handle, where->bh);
700                 if (err)
701                         goto err_out;
702         }
703         /* That's it */
704
705         *where->p = where->key;
706
707         /*
708          * Update the host buffer_head or inode to point to more just allocated
709          * direct blocks blocks
710          */
711         if (num == 0 && blks > 1) {
712                 current_block = le32_to_cpu(where->key) + 1;
713                 for (i = 1; i < blks; i++)
714                         *(where->p + i ) = cpu_to_le32(current_block++);
715         }
716
717         /*
718          * update the most recently allocated logical & physical block
719          * in i_block_alloc_info, to assist find the proper goal block for next
720          * allocation
721          */
722         if (block_i) {
723                 block_i->last_alloc_logical_block = block + blks - 1;
724                 block_i->last_alloc_physical_block =
725                                 le32_to_cpu(where[num].key) + blks - 1;
726         }
727
728         /* We are done with atomic stuff, now do the rest of housekeeping */
729
730         inode->i_ctime = CURRENT_TIME_SEC;
731         ext4_mark_inode_dirty(handle, inode);
732
733         /* had we spliced it onto indirect block? */
734         if (where->bh) {
735                 /*
736                  * If we spliced it onto an indirect block, we haven't
737                  * altered the inode.  Note however that if it is being spliced
738                  * onto an indirect block at the very end of the file (the
739                  * file is growing) then we *will* alter the inode to reflect
740                  * the new i_size.  But that is not done here - it is done in
741                  * generic_commit_write->__mark_inode_dirty->ext4_dirty_inode.
742                  */
743                 jbd_debug(5, "splicing indirect only\n");
744                 BUFFER_TRACE(where->bh, "call ext4_journal_dirty_metadata");
745                 err = ext4_journal_dirty_metadata(handle, where->bh);
746                 if (err)
747                         goto err_out;
748         } else {
749                 /*
750                  * OK, we spliced it into the inode itself on a direct block.
751                  * Inode was dirtied above.
752                  */
753                 jbd_debug(5, "splicing direct\n");
754         }
755         return err;
756
757 err_out:
758         for (i = 1; i <= num; i++) {
759                 BUFFER_TRACE(where[i].bh, "call jbd2_journal_forget");
760                 ext4_journal_forget(handle, where[i].bh);
761                 ext4_free_blocks(handle,inode,le32_to_cpu(where[i-1].key),1);
762         }
763         ext4_free_blocks(handle, inode, le32_to_cpu(where[num].key), blks);
764
765         return err;
766 }
767
768 /*
769  * Allocation strategy is simple: if we have to allocate something, we will
770  * have to go the whole way to leaf. So let's do it before attaching anything
771  * to tree, set linkage between the newborn blocks, write them if sync is
772  * required, recheck the path, free and repeat if check fails, otherwise
773  * set the last missing link (that will protect us from any truncate-generated
774  * removals - all blocks on the path are immune now) and possibly force the
775  * write on the parent block.
776  * That has a nice additional property: no special recovery from the failed
777  * allocations is needed - we simply release blocks and do not touch anything
778  * reachable from inode.
779  *
780  * `handle' can be NULL if create == 0.
781  *
782  * The BKL may not be held on entry here.  Be sure to take it early.
783  * return > 0, # of blocks mapped or allocated.
784  * return = 0, if plain lookup failed.
785  * return < 0, error case.
786  */
787 int ext4_get_blocks_handle(handle_t *handle, struct inode *inode,
788                 sector_t iblock, unsigned long maxblocks,
789                 struct buffer_head *bh_result,
790                 int create, int extend_disksize)
791 {
792         int err = -EIO;
793         int offsets[4];
794         Indirect chain[4];
795         Indirect *partial;
796         ext4_fsblk_t goal;
797         int indirect_blks;
798         int blocks_to_boundary = 0;
799         int depth;
800         struct ext4_inode_info *ei = EXT4_I(inode);
801         int count = 0;
802         ext4_fsblk_t first_block = 0;
803
804
805         J_ASSERT(!(EXT4_I(inode)->i_flags & EXT4_EXTENTS_FL));
806         J_ASSERT(handle != NULL || create == 0);
807         depth = ext4_block_to_path(inode,iblock,offsets,&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                         if (!verify_chain(chain, partial)) {
824                                 /*
825                                  * Indirect block might be removed by
826                                  * truncate while we were reading it.
827                                  * Handling of that case: forget what we've
828                                  * got now. Flag the err as EAGAIN, so it
829                                  * will reread.
830                                  */
831                                 err = -EAGAIN;
832                                 count = 0;
833                                 break;
834                         }
835                         blk = le32_to_cpu(*(chain[depth-1].p + count));
836
837                         if (blk == first_block + count)
838                                 count++;
839                         else
840                                 break;
841                 }
842                 if (err != -EAGAIN)
843                         goto got_it;
844         }
845
846         /* Next simple case - plain lookup or failed read of indirect block */
847         if (!create || err == -EIO)
848                 goto cleanup;
849
850         mutex_lock(&ei->truncate_mutex);
851
852         /*
853          * If the indirect block is missing while we are reading
854          * the chain(ext4_get_branch() returns -EAGAIN err), or
855          * if the chain has been changed after we grab the semaphore,
856          * (either because another process truncated this branch, or
857          * another get_block allocated this branch) re-grab the chain to see if
858          * the request block has been allocated or not.
859          *
860          * Since we already block the truncate/other get_block
861          * at this point, we will have the current copy of the chain when we
862          * splice the branch into the tree.
863          */
864         if (err == -EAGAIN || !verify_chain(chain, partial)) {
865                 while (partial > chain) {
866                         brelse(partial->bh);
867                         partial--;
868                 }
869                 partial = ext4_get_branch(inode, depth, offsets, chain, &err);
870                 if (!partial) {
871                         count++;
872                         mutex_unlock(&ei->truncate_mutex);
873                         if (err)
874                                 goto cleanup;
875                         clear_buffer_new(bh_result);
876                         goto got_it;
877                 }
878         }
879
880         /*
881          * Okay, we need to do block allocation.  Lazily initialize the block
882          * allocation info here if necessary
883         */
884         if (S_ISREG(inode->i_mode) && (!ei->i_block_alloc_info))
885                 ext4_init_block_alloc_info(inode);
886
887         goal = ext4_find_goal(inode, iblock, chain, partial);
888
889         /* the number of blocks need to allocate for [d,t]indirect blocks */
890         indirect_blks = (chain + depth) - partial - 1;
891
892         /*
893          * Next look up the indirect map to count the totoal number of
894          * direct blocks to allocate for this branch.
895          */
896         count = ext4_blks_to_allocate(partial, indirect_blks,
897                                         maxblocks, blocks_to_boundary);
898         /*
899          * Block out ext4_truncate while we alter the tree
900          */
901         err = ext4_alloc_branch(handle, inode, indirect_blks, &count, goal,
902                                 offsets + (partial - chain), partial);
903
904         /*
905          * The ext4_splice_branch call will free and forget any buffers
906          * on the new chain if there is a failure, but that risks using
907          * up transaction credits, especially for bitmaps where the
908          * credits cannot be returned.  Can we handle this somehow?  We
909          * may need to return -EAGAIN upwards in the worst case.  --sct
910          */
911         if (!err)
912                 err = ext4_splice_branch(handle, inode, iblock,
913                                         partial, indirect_blks, count);
914         /*
915          * i_disksize growing is protected by truncate_mutex.  Don't forget to
916          * protect it if you're about to implement concurrent
917          * ext4_get_block() -bzzz
918         */
919         if (!err && extend_disksize && inode->i_size > ei->i_disksize)
920                 ei->i_disksize = inode->i_size;
921         mutex_unlock(&ei->truncate_mutex);
922         if (err)
923                 goto cleanup;
924
925         set_buffer_new(bh_result);
926 got_it:
927         map_bh(bh_result, inode->i_sb, le32_to_cpu(chain[depth-1].key));
928         if (count > blocks_to_boundary)
929                 set_buffer_boundary(bh_result);
930         err = count;
931         /* Clean up and exit */
932         partial = chain + depth - 1;    /* the whole chain */
933 cleanup:
934         while (partial > chain) {
935                 BUFFER_TRACE(partial->bh, "call brelse");
936                 brelse(partial->bh);
937                 partial--;
938         }
939         BUFFER_TRACE(bh_result, "returned");
940 out:
941         return err;
942 }
943
944 #define DIO_CREDITS (EXT4_RESERVE_TRANS_BLOCKS + 32)
945
946 static int ext4_get_block(struct inode *inode, sector_t iblock,
947                         struct buffer_head *bh_result, int create)
948 {
949         handle_t *handle = journal_current_handle();
950         int ret = 0;
951         unsigned max_blocks = bh_result->b_size >> inode->i_blkbits;
952
953         if (!create)
954                 goto get_block;         /* A read */
955
956         if (max_blocks == 1)
957                 goto get_block;         /* A single block get */
958
959         if (handle->h_transaction->t_state == T_LOCKED) {
960                 /*
961                  * Huge direct-io writes can hold off commits for long
962                  * periods of time.  Let this commit run.
963                  */
964                 ext4_journal_stop(handle);
965                 handle = ext4_journal_start(inode, DIO_CREDITS);
966                 if (IS_ERR(handle))
967                         ret = PTR_ERR(handle);
968                 goto get_block;
969         }
970
971         if (handle->h_buffer_credits <= EXT4_RESERVE_TRANS_BLOCKS) {
972                 /*
973                  * Getting low on buffer credits...
974                  */
975                 ret = ext4_journal_extend(handle, DIO_CREDITS);
976                 if (ret > 0) {
977                         /*
978                          * Couldn't extend the transaction.  Start a new one.
979                          */
980                         ret = ext4_journal_restart(handle, DIO_CREDITS);
981                 }
982         }
983
984 get_block:
985         if (ret == 0) {
986                 ret = ext4_get_blocks_wrap(handle, inode, iblock,
987                                         max_blocks, bh_result, create, 0);
988                 if (ret > 0) {
989                         bh_result->b_size = (ret << inode->i_blkbits);
990                         ret = 0;
991                 }
992         }
993         return ret;
994 }
995
996 /*
997  * `handle' can be NULL if create is zero
998  */
999 struct buffer_head *ext4_getblk(handle_t *handle, struct inode *inode,
1000                                 long block, int create, int *errp)
1001 {
1002         struct buffer_head dummy;
1003         int fatal = 0, err;
1004
1005         J_ASSERT(handle != NULL || create == 0);
1006
1007         dummy.b_state = 0;
1008         dummy.b_blocknr = -1000;
1009         buffer_trace_init(&dummy.b_history);
1010         err = ext4_get_blocks_wrap(handle, inode, block, 1,
1011                                         &dummy, create, 1);
1012         /*
1013          * ext4_get_blocks_handle() returns number of blocks
1014          * mapped. 0 in case of a HOLE.
1015          */
1016         if (err > 0) {
1017                 if (err > 1)
1018                         WARN_ON(1);
1019                 err = 0;
1020         }
1021         *errp = err;
1022         if (!err && buffer_mapped(&dummy)) {
1023                 struct buffer_head *bh;
1024                 bh = sb_getblk(inode->i_sb, dummy.b_blocknr);
1025                 if (!bh) {
1026                         *errp = -EIO;
1027                         goto err;
1028                 }
1029                 if (buffer_new(&dummy)) {
1030                         J_ASSERT(create != 0);
1031                         J_ASSERT(handle != 0);
1032
1033                         /*
1034                          * Now that we do not always journal data, we should
1035                          * keep in mind whether this should always journal the
1036                          * new buffer as metadata.  For now, regular file
1037                          * writes use ext4_get_block instead, so it's not a
1038                          * problem.
1039                          */
1040                         lock_buffer(bh);
1041                         BUFFER_TRACE(bh, "call get_create_access");
1042                         fatal = ext4_journal_get_create_access(handle, bh);
1043                         if (!fatal && !buffer_uptodate(bh)) {
1044                                 memset(bh->b_data,0,inode->i_sb->s_blocksize);
1045                                 set_buffer_uptodate(bh);
1046                         }
1047                         unlock_buffer(bh);
1048                         BUFFER_TRACE(bh, "call ext4_journal_dirty_metadata");
1049                         err = ext4_journal_dirty_metadata(handle, bh);
1050                         if (!fatal)
1051                                 fatal = err;
1052                 } else {
1053                         BUFFER_TRACE(bh, "not a new buffer");
1054                 }
1055                 if (fatal) {
1056                         *errp = fatal;
1057                         brelse(bh);
1058                         bh = NULL;
1059                 }
1060                 return bh;
1061         }
1062 err:
1063         return NULL;
1064 }
1065
1066 struct buffer_head *ext4_bread(handle_t *handle, struct inode *inode,
1067                                int block, int create, int *err)
1068 {
1069         struct buffer_head * bh;
1070
1071         bh = ext4_getblk(handle, inode, block, create, err);
1072         if (!bh)
1073                 return bh;
1074         if (buffer_uptodate(bh))
1075                 return bh;
1076         ll_rw_block(READ_META, 1, &bh);
1077         wait_on_buffer(bh);
1078         if (buffer_uptodate(bh))
1079                 return bh;
1080         put_bh(bh);
1081         *err = -EIO;
1082         return NULL;
1083 }
1084
1085 static int walk_page_buffers(   handle_t *handle,
1086                                 struct buffer_head *head,
1087                                 unsigned from,
1088                                 unsigned to,
1089                                 int *partial,
1090                                 int (*fn)(      handle_t *handle,
1091                                                 struct buffer_head *bh))
1092 {
1093         struct buffer_head *bh;
1094         unsigned block_start, block_end;
1095         unsigned blocksize = head->b_size;
1096         int err, ret = 0;
1097         struct buffer_head *next;
1098
1099         for (   bh = head, block_start = 0;
1100                 ret == 0 && (bh != head || !block_start);
1101                 block_start = block_end, bh = next)
1102         {
1103                 next = bh->b_this_page;
1104                 block_end = block_start + blocksize;
1105                 if (block_end <= from || block_start >= to) {
1106                         if (partial && !buffer_uptodate(bh))
1107                                 *partial = 1;
1108                         continue;
1109                 }
1110                 err = (*fn)(handle, bh);
1111                 if (!ret)
1112                         ret = err;
1113         }
1114         return ret;
1115 }
1116
1117 /*
1118  * To preserve ordering, it is essential that the hole instantiation and
1119  * the data write be encapsulated in a single transaction.  We cannot
1120  * close off a transaction and start a new one between the ext4_get_block()
1121  * and the commit_write().  So doing the jbd2_journal_start at the start of
1122  * prepare_write() is the right place.
1123  *
1124  * Also, this function can nest inside ext4_writepage() ->
1125  * block_write_full_page(). In that case, we *know* that ext4_writepage()
1126  * has generated enough buffer credits to do the whole page.  So we won't
1127  * block on the journal in that case, which is good, because the caller may
1128  * be PF_MEMALLOC.
1129  *
1130  * By accident, ext4 can be reentered when a transaction is open via
1131  * quota file writes.  If we were to commit the transaction while thus
1132  * reentered, there can be a deadlock - we would be holding a quota
1133  * lock, and the commit would never complete if another thread had a
1134  * transaction open and was blocking on the quota lock - a ranking
1135  * violation.
1136  *
1137  * So what we do is to rely on the fact that jbd2_journal_stop/journal_start
1138  * will _not_ run commit under these circumstances because handle->h_ref
1139  * is elevated.  We'll still have enough credits for the tiny quotafile
1140  * write.
1141  */
1142 static int do_journal_get_write_access(handle_t *handle,
1143                                         struct buffer_head *bh)
1144 {
1145         if (!buffer_mapped(bh) || buffer_freed(bh))
1146                 return 0;
1147         return ext4_journal_get_write_access(handle, bh);
1148 }
1149
1150 /*
1151  * The idea of this helper function is following:
1152  * if prepare_write has allocated some blocks, but not all of them, the
1153  * transaction must include the content of the newly allocated blocks.
1154  * This content is expected to be set to zeroes by block_prepare_write().
1155  * 2006/10/14  SAW
1156  */
1157 static int ext4_prepare_failure(struct file *file, struct page *page,
1158                                 unsigned from, unsigned to)
1159 {
1160         struct address_space *mapping;
1161         struct buffer_head *bh, *head, *next;
1162         unsigned block_start, block_end;
1163         unsigned blocksize;
1164         int ret;
1165         handle_t *handle = ext4_journal_current_handle();
1166
1167         mapping = page->mapping;
1168         if (ext4_should_writeback_data(mapping->host)) {
1169                 /* optimization: no constraints about data */
1170 skip:
1171                 return ext4_journal_stop(handle);
1172         }
1173
1174         head = page_buffers(page);
1175         blocksize = head->b_size;
1176         for (   bh = head, block_start = 0;
1177                 bh != head || !block_start;
1178                 block_start = block_end, bh = next)
1179         {
1180                 next = bh->b_this_page;
1181                 block_end = block_start + blocksize;
1182                 if (block_end <= from)
1183                         continue;
1184                 if (block_start >= to) {
1185                         block_start = to;
1186                         break;
1187                 }
1188                 if (!buffer_mapped(bh))
1189                 /* prepare_write failed on this bh */
1190                         break;
1191                 if (ext4_should_journal_data(mapping->host)) {
1192                         ret = do_journal_get_write_access(handle, bh);
1193                         if (ret) {
1194                                 ext4_journal_stop(handle);
1195                                 return ret;
1196                         }
1197                 }
1198         /*
1199          * block_start here becomes the first block where the current iteration
1200          * of prepare_write failed.
1201          */
1202         }
1203         if (block_start <= from)
1204                 goto skip;
1205
1206         /* commit allocated and zeroed buffers */
1207         return mapping->a_ops->commit_write(file, page, from, block_start);
1208 }
1209
1210 static int ext4_prepare_write(struct file *file, struct page *page,
1211                               unsigned from, unsigned to)
1212 {
1213         struct inode *inode = page->mapping->host;
1214         int ret, ret2;
1215         int needed_blocks = ext4_writepage_trans_blocks(inode);
1216         handle_t *handle;
1217         int retries = 0;
1218
1219 retry:
1220         handle = ext4_journal_start(inode, needed_blocks);
1221         if (IS_ERR(handle))
1222                 return PTR_ERR(handle);
1223         if (test_opt(inode->i_sb, NOBH) && ext4_should_writeback_data(inode))
1224                 ret = nobh_prepare_write(page, from, to, ext4_get_block);
1225         else
1226                 ret = block_prepare_write(page, from, to, ext4_get_block);
1227         if (ret)
1228                 goto failure;
1229
1230         if (ext4_should_journal_data(inode)) {
1231                 ret = walk_page_buffers(handle, page_buffers(page),
1232                                 from, to, NULL, do_journal_get_write_access);
1233                 if (ret)
1234                         /* fatal error, just put the handle and return */
1235                         ext4_journal_stop(handle);
1236         }
1237         return ret;
1238
1239 failure:
1240         ret2 = ext4_prepare_failure(file, page, from, to);
1241         if (ret2 < 0)
1242                 return ret2;
1243         if (ret == -ENOSPC && ext4_should_retry_alloc(inode->i_sb, &retries))
1244                 goto retry;
1245         /* retry number exceeded, or other error like -EDQUOT */
1246         return ret;
1247 }
1248
1249 int ext4_journal_dirty_data(handle_t *handle, struct buffer_head *bh)
1250 {
1251         int err = jbd2_journal_dirty_data(handle, bh);
1252         if (err)
1253                 ext4_journal_abort_handle(__FUNCTION__, __FUNCTION__,
1254                                                 bh, handle,err);
1255         return err;
1256 }
1257
1258 /* For commit_write() in data=journal mode */
1259 static int commit_write_fn(handle_t *handle, struct buffer_head *bh)
1260 {
1261         if (!buffer_mapped(bh) || buffer_freed(bh))
1262                 return 0;
1263         set_buffer_uptodate(bh);
1264         return ext4_journal_dirty_metadata(handle, bh);
1265 }
1266
1267 /*
1268  * We need to pick up the new inode size which generic_commit_write gave us
1269  * `file' can be NULL - eg, when called from page_symlink().
1270  *
1271  * ext4 never places buffers on inode->i_mapping->private_list.  metadata
1272  * buffers are managed internally.
1273  */
1274 static int ext4_ordered_commit_write(struct file *file, struct page *page,
1275                              unsigned from, unsigned to)
1276 {
1277         handle_t *handle = ext4_journal_current_handle();
1278         struct inode *inode = page->mapping->host;
1279         int ret = 0, ret2;
1280
1281         ret = walk_page_buffers(handle, page_buffers(page),
1282                 from, to, NULL, ext4_journal_dirty_data);
1283
1284         if (ret == 0) {
1285                 /*
1286                  * generic_commit_write() will run mark_inode_dirty() if i_size
1287                  * changes.  So let's piggyback the i_disksize mark_inode_dirty
1288                  * into that.
1289                  */
1290                 loff_t new_i_size;
1291
1292                 new_i_size = ((loff_t)page->index << PAGE_CACHE_SHIFT) + to;
1293                 if (new_i_size > EXT4_I(inode)->i_disksize)
1294                         EXT4_I(inode)->i_disksize = new_i_size;
1295                 ret = generic_commit_write(file, page, from, to);
1296         }
1297         ret2 = ext4_journal_stop(handle);
1298         if (!ret)
1299                 ret = ret2;
1300         return ret;
1301 }
1302
1303 static int ext4_writeback_commit_write(struct file *file, struct page *page,
1304                              unsigned from, unsigned to)
1305 {
1306         handle_t *handle = ext4_journal_current_handle();
1307         struct inode *inode = page->mapping->host;
1308         int ret = 0, ret2;
1309         loff_t new_i_size;
1310
1311         new_i_size = ((loff_t)page->index << PAGE_CACHE_SHIFT) + to;
1312         if (new_i_size > EXT4_I(inode)->i_disksize)
1313                 EXT4_I(inode)->i_disksize = new_i_size;
1314
1315         if (test_opt(inode->i_sb, NOBH) && ext4_should_writeback_data(inode))
1316                 ret = nobh_commit_write(file, page, from, to);
1317         else
1318                 ret = generic_commit_write(file, page, from, to);
1319
1320         ret2 = ext4_journal_stop(handle);
1321         if (!ret)
1322                 ret = ret2;
1323         return ret;
1324 }
1325
1326 static int ext4_journalled_commit_write(struct file *file,
1327                         struct page *page, unsigned from, unsigned to)
1328 {
1329         handle_t *handle = ext4_journal_current_handle();
1330         struct inode *inode = page->mapping->host;
1331         int ret = 0, ret2;
1332         int partial = 0;
1333         loff_t pos;
1334
1335         /*
1336          * Here we duplicate the generic_commit_write() functionality
1337          */
1338         pos = ((loff_t)page->index << PAGE_CACHE_SHIFT) + to;
1339
1340         ret = walk_page_buffers(handle, page_buffers(page), from,
1341                                 to, &partial, commit_write_fn);
1342         if (!partial)
1343                 SetPageUptodate(page);
1344         if (pos > inode->i_size)
1345                 i_size_write(inode, pos);
1346         EXT4_I(inode)->i_state |= EXT4_STATE_JDATA;
1347         if (inode->i_size > EXT4_I(inode)->i_disksize) {
1348                 EXT4_I(inode)->i_disksize = inode->i_size;
1349                 ret2 = ext4_mark_inode_dirty(handle, inode);
1350                 if (!ret)
1351                         ret = ret2;
1352         }
1353         ret2 = ext4_journal_stop(handle);
1354         if (!ret)
1355                 ret = ret2;
1356         return ret;
1357 }
1358
1359 /*
1360  * bmap() is special.  It gets used by applications such as lilo and by
1361  * the swapper to find the on-disk block of a specific piece of data.
1362  *
1363  * Naturally, this is dangerous if the block concerned is still in the
1364  * journal.  If somebody makes a swapfile on an ext4 data-journaling
1365  * filesystem and enables swap, then they may get a nasty shock when the
1366  * data getting swapped to that swapfile suddenly gets overwritten by
1367  * the original zero's written out previously to the journal and
1368  * awaiting writeback in the kernel's buffer cache.
1369  *
1370  * So, if we see any bmap calls here on a modified, data-journaled file,
1371  * take extra steps to flush any blocks which might be in the cache.
1372  */
1373 static sector_t ext4_bmap(struct address_space *mapping, sector_t block)
1374 {
1375         struct inode *inode = mapping->host;
1376         journal_t *journal;
1377         int err;
1378
1379         if (EXT4_I(inode)->i_state & EXT4_STATE_JDATA) {
1380                 /*
1381                  * This is a REALLY heavyweight approach, but the use of
1382                  * bmap on dirty files is expected to be extremely rare:
1383                  * only if we run lilo or swapon on a freshly made file
1384                  * do we expect this to happen.
1385                  *
1386                  * (bmap requires CAP_SYS_RAWIO so this does not
1387                  * represent an unprivileged user DOS attack --- we'd be
1388                  * in trouble if mortal users could trigger this path at
1389                  * will.)
1390                  *
1391                  * NB. EXT4_STATE_JDATA is not set on files other than
1392                  * regular files.  If somebody wants to bmap a directory
1393                  * or symlink and gets confused because the buffer
1394                  * hasn't yet been flushed to disk, they deserve
1395                  * everything they get.
1396                  */
1397
1398                 EXT4_I(inode)->i_state &= ~EXT4_STATE_JDATA;
1399                 journal = EXT4_JOURNAL(inode);
1400                 jbd2_journal_lock_updates(journal);
1401                 err = jbd2_journal_flush(journal);
1402                 jbd2_journal_unlock_updates(journal);
1403
1404                 if (err)
1405                         return 0;
1406         }
1407
1408         return generic_block_bmap(mapping,block,ext4_get_block);
1409 }
1410
1411 static int bget_one(handle_t *handle, struct buffer_head *bh)
1412 {
1413         get_bh(bh);
1414         return 0;
1415 }
1416
1417 static int bput_one(handle_t *handle, struct buffer_head *bh)
1418 {
1419         put_bh(bh);
1420         return 0;
1421 }
1422
1423 static int jbd2_journal_dirty_data_fn(handle_t *handle, struct buffer_head *bh)
1424 {
1425         if (buffer_mapped(bh))
1426                 return ext4_journal_dirty_data(handle, bh);
1427         return 0;
1428 }
1429
1430 /*
1431  * Note that we always start a transaction even if we're not journalling
1432  * data.  This is to preserve ordering: any hole instantiation within
1433  * __block_write_full_page -> ext4_get_block() should be journalled
1434  * along with the data so we don't crash and then get metadata which
1435  * refers to old data.
1436  *
1437  * In all journalling modes block_write_full_page() will start the I/O.
1438  *
1439  * Problem:
1440  *
1441  *      ext4_writepage() -> kmalloc() -> __alloc_pages() -> page_launder() ->
1442  *              ext4_writepage()
1443  *
1444  * Similar for:
1445  *
1446  *      ext4_file_write() -> generic_file_write() -> __alloc_pages() -> ...
1447  *
1448  * Same applies to ext4_get_block().  We will deadlock on various things like
1449  * lock_journal and i_truncate_mutex.
1450  *
1451  * Setting PF_MEMALLOC here doesn't work - too many internal memory
1452  * allocations fail.
1453  *
1454  * 16May01: If we're reentered then journal_current_handle() will be
1455  *          non-zero. We simply *return*.
1456  *
1457  * 1 July 2001: @@@ FIXME:
1458  *   In journalled data mode, a data buffer may be metadata against the
1459  *   current transaction.  But the same file is part of a shared mapping
1460  *   and someone does a writepage() on it.
1461  *
1462  *   We will move the buffer onto the async_data list, but *after* it has
1463  *   been dirtied. So there's a small window where we have dirty data on
1464  *   BJ_Metadata.
1465  *
1466  *   Note that this only applies to the last partial page in the file.  The
1467  *   bit which block_write_full_page() uses prepare/commit for.  (That's
1468  *   broken code anyway: it's wrong for msync()).
1469  *
1470  *   It's a rare case: affects the final partial page, for journalled data
1471  *   where the file is subject to bith write() and writepage() in the same
1472  *   transction.  To fix it we'll need a custom block_write_full_page().
1473  *   We'll probably need that anyway for journalling writepage() output.
1474  *
1475  * We don't honour synchronous mounts for writepage().  That would be
1476  * disastrous.  Any write() or metadata operation will sync the fs for
1477  * us.
1478  *
1479  * AKPM2: if all the page's buffers are mapped to disk and !data=journal,
1480  * we don't need to open a transaction here.
1481  */
1482 static int ext4_ordered_writepage(struct page *page,
1483                                 struct writeback_control *wbc)
1484 {
1485         struct inode *inode = page->mapping->host;
1486         struct buffer_head *page_bufs;
1487         handle_t *handle = NULL;
1488         int ret = 0;
1489         int err;
1490
1491         J_ASSERT(PageLocked(page));
1492
1493         /*
1494          * We give up here if we're reentered, because it might be for a
1495          * different filesystem.
1496          */
1497         if (ext4_journal_current_handle())
1498                 goto out_fail;
1499
1500         handle = ext4_journal_start(inode, ext4_writepage_trans_blocks(inode));
1501
1502         if (IS_ERR(handle)) {
1503                 ret = PTR_ERR(handle);
1504                 goto out_fail;
1505         }
1506
1507         if (!page_has_buffers(page)) {
1508                 create_empty_buffers(page, inode->i_sb->s_blocksize,
1509                                 (1 << BH_Dirty)|(1 << BH_Uptodate));
1510         }
1511         page_bufs = page_buffers(page);
1512         walk_page_buffers(handle, page_bufs, 0,
1513                         PAGE_CACHE_SIZE, NULL, bget_one);
1514
1515         ret = block_write_full_page(page, ext4_get_block, wbc);
1516
1517         /*
1518          * The page can become unlocked at any point now, and
1519          * truncate can then come in and change things.  So we
1520          * can't touch *page from now on.  But *page_bufs is
1521          * safe due to elevated refcount.
1522          */
1523
1524         /*
1525          * And attach them to the current transaction.  But only if
1526          * block_write_full_page() succeeded.  Otherwise they are unmapped,
1527          * and generally junk.
1528          */
1529         if (ret == 0) {
1530                 err = walk_page_buffers(handle, page_bufs, 0, PAGE_CACHE_SIZE,
1531                                         NULL, jbd2_journal_dirty_data_fn);
1532                 if (!ret)
1533                         ret = err;
1534         }
1535         walk_page_buffers(handle, page_bufs, 0,
1536                         PAGE_CACHE_SIZE, NULL, bput_one);
1537         err = ext4_journal_stop(handle);
1538         if (!ret)
1539                 ret = err;
1540         return ret;
1541
1542 out_fail:
1543         redirty_page_for_writepage(wbc, page);
1544         unlock_page(page);
1545         return ret;
1546 }
1547
1548 static int ext4_writeback_writepage(struct page *page,
1549                                 struct writeback_control *wbc)
1550 {
1551         struct inode *inode = page->mapping->host;
1552         handle_t *handle = NULL;
1553         int ret = 0;
1554         int err;
1555
1556         if (ext4_journal_current_handle())
1557                 goto out_fail;
1558
1559         handle = ext4_journal_start(inode, ext4_writepage_trans_blocks(inode));
1560         if (IS_ERR(handle)) {
1561                 ret = PTR_ERR(handle);
1562                 goto out_fail;
1563         }
1564
1565         if (test_opt(inode->i_sb, NOBH) && ext4_should_writeback_data(inode))
1566                 ret = nobh_writepage(page, ext4_get_block, wbc);
1567         else
1568                 ret = block_write_full_page(page, ext4_get_block, wbc);
1569
1570         err = ext4_journal_stop(handle);
1571         if (!ret)
1572                 ret = err;
1573         return ret;
1574
1575 out_fail:
1576         redirty_page_for_writepage(wbc, page);
1577         unlock_page(page);
1578         return ret;
1579 }
1580
1581 static int ext4_journalled_writepage(struct page *page,
1582                                 struct writeback_control *wbc)
1583 {
1584         struct inode *inode = page->mapping->host;
1585         handle_t *handle = NULL;
1586         int ret = 0;
1587         int err;
1588
1589         if (ext4_journal_current_handle())
1590                 goto no_write;
1591
1592         handle = ext4_journal_start(inode, ext4_writepage_trans_blocks(inode));
1593         if (IS_ERR(handle)) {
1594                 ret = PTR_ERR(handle);
1595                 goto no_write;
1596         }
1597
1598         if (!page_has_buffers(page) || PageChecked(page)) {
1599                 /*
1600                  * It's mmapped pagecache.  Add buffers and journal it.  There
1601                  * doesn't seem much point in redirtying the page here.
1602                  */
1603                 ClearPageChecked(page);
1604                 ret = block_prepare_write(page, 0, PAGE_CACHE_SIZE,
1605                                         ext4_get_block);
1606                 if (ret != 0) {
1607                         ext4_journal_stop(handle);
1608                         goto out_unlock;
1609                 }
1610                 ret = walk_page_buffers(handle, page_buffers(page), 0,
1611                         PAGE_CACHE_SIZE, NULL, do_journal_get_write_access);
1612
1613                 err = walk_page_buffers(handle, page_buffers(page), 0,
1614                                 PAGE_CACHE_SIZE, NULL, commit_write_fn);
1615                 if (ret == 0)
1616                         ret = err;
1617                 EXT4_I(inode)->i_state |= EXT4_STATE_JDATA;
1618                 unlock_page(page);
1619         } else {
1620                 /*
1621                  * It may be a page full of checkpoint-mode buffers.  We don't
1622                  * really know unless we go poke around in the buffer_heads.
1623                  * But block_write_full_page will do the right thing.
1624                  */
1625                 ret = block_write_full_page(page, ext4_get_block, wbc);
1626         }
1627         err = ext4_journal_stop(handle);
1628         if (!ret)
1629                 ret = err;
1630 out:
1631         return ret;
1632
1633 no_write:
1634         redirty_page_for_writepage(wbc, page);
1635 out_unlock:
1636         unlock_page(page);
1637         goto out;
1638 }
1639
1640 static int ext4_readpage(struct file *file, struct page *page)
1641 {
1642         return mpage_readpage(page, ext4_get_block);
1643 }
1644
1645 static int
1646 ext4_readpages(struct file *file, struct address_space *mapping,
1647                 struct list_head *pages, unsigned nr_pages)
1648 {
1649         return mpage_readpages(mapping, pages, nr_pages, ext4_get_block);
1650 }
1651
1652 static void ext4_invalidatepage(struct page *page, unsigned long offset)
1653 {
1654         journal_t *journal = EXT4_JOURNAL(page->mapping->host);
1655
1656         /*
1657          * If it's a full truncate we just forget about the pending dirtying
1658          */
1659         if (offset == 0)
1660                 ClearPageChecked(page);
1661
1662         jbd2_journal_invalidatepage(journal, page, offset);
1663 }
1664
1665 static int ext4_releasepage(struct page *page, gfp_t wait)
1666 {
1667         journal_t *journal = EXT4_JOURNAL(page->mapping->host);
1668
1669         WARN_ON(PageChecked(page));
1670         if (!page_has_buffers(page))
1671                 return 0;
1672         return jbd2_journal_try_to_free_buffers(journal, page, wait);
1673 }
1674
1675 /*
1676  * If the O_DIRECT write will extend the file then add this inode to the
1677  * orphan list.  So recovery will truncate it back to the original size
1678  * if the machine crashes during the write.
1679  *
1680  * If the O_DIRECT write is intantiating holes inside i_size and the machine
1681  * crashes then stale disk data _may_ be exposed inside the file.
1682  */
1683 static ssize_t ext4_direct_IO(int rw, struct kiocb *iocb,
1684                         const struct iovec *iov, loff_t offset,
1685                         unsigned long nr_segs)
1686 {
1687         struct file *file = iocb->ki_filp;
1688         struct inode *inode = file->f_mapping->host;
1689         struct ext4_inode_info *ei = EXT4_I(inode);
1690         handle_t *handle = NULL;
1691         ssize_t ret;
1692         int orphan = 0;
1693         size_t count = iov_length(iov, nr_segs);
1694
1695         if (rw == WRITE) {
1696                 loff_t final_size = offset + count;
1697
1698                 handle = ext4_journal_start(inode, DIO_CREDITS);
1699                 if (IS_ERR(handle)) {
1700                         ret = PTR_ERR(handle);
1701                         goto out;
1702                 }
1703                 if (final_size > inode->i_size) {
1704                         ret = ext4_orphan_add(handle, inode);
1705                         if (ret)
1706                                 goto out_stop;
1707                         orphan = 1;
1708                         ei->i_disksize = inode->i_size;
1709                 }
1710         }
1711
1712         ret = blockdev_direct_IO(rw, iocb, inode, inode->i_sb->s_bdev, iov,
1713                                  offset, nr_segs,
1714                                  ext4_get_block, NULL);
1715
1716         /*
1717          * Reacquire the handle: ext4_get_block() can restart the transaction
1718          */
1719         handle = journal_current_handle();
1720
1721 out_stop:
1722         if (handle) {
1723                 int err;
1724
1725                 if (orphan && inode->i_nlink)
1726                         ext4_orphan_del(handle, inode);
1727                 if (orphan && ret > 0) {
1728                         loff_t end = offset + ret;
1729                         if (end > inode->i_size) {
1730                                 ei->i_disksize = end;
1731                                 i_size_write(inode, end);
1732                                 /*
1733                                  * We're going to return a positive `ret'
1734                                  * here due to non-zero-length I/O, so there's
1735                                  * no way of reporting error returns from
1736                                  * ext4_mark_inode_dirty() to userspace.  So
1737                                  * ignore it.
1738                                  */
1739                                 ext4_mark_inode_dirty(handle, inode);
1740                         }
1741                 }
1742                 err = ext4_journal_stop(handle);
1743                 if (ret == 0)
1744                         ret = err;
1745         }
1746 out:
1747         return ret;
1748 }
1749
1750 /*
1751  * Pages can be marked dirty completely asynchronously from ext4's journalling
1752  * activity.  By filemap_sync_pte(), try_to_unmap_one(), etc.  We cannot do
1753  * much here because ->set_page_dirty is called under VFS locks.  The page is
1754  * not necessarily locked.
1755  *
1756  * We cannot just dirty the page and leave attached buffers clean, because the
1757  * buffers' dirty state is "definitive".  We cannot just set the buffers dirty
1758  * or jbddirty because all the journalling code will explode.
1759  *
1760  * So what we do is to mark the page "pending dirty" and next time writepage
1761  * is called, propagate that into the buffers appropriately.
1762  */
1763 static int ext4_journalled_set_page_dirty(struct page *page)
1764 {
1765         SetPageChecked(page);
1766         return __set_page_dirty_nobuffers(page);
1767 }
1768
1769 static const struct address_space_operations ext4_ordered_aops = {
1770         .readpage       = ext4_readpage,
1771         .readpages      = ext4_readpages,
1772         .writepage      = ext4_ordered_writepage,
1773         .sync_page      = block_sync_page,
1774         .prepare_write  = ext4_prepare_write,
1775         .commit_write   = ext4_ordered_commit_write,
1776         .bmap           = ext4_bmap,
1777         .invalidatepage = ext4_invalidatepage,
1778         .releasepage    = ext4_releasepage,
1779         .direct_IO      = ext4_direct_IO,
1780         .migratepage    = buffer_migrate_page,
1781 };
1782
1783 static const struct address_space_operations ext4_writeback_aops = {
1784         .readpage       = ext4_readpage,
1785         .readpages      = ext4_readpages,
1786         .writepage      = ext4_writeback_writepage,
1787         .sync_page      = block_sync_page,
1788         .prepare_write  = ext4_prepare_write,
1789         .commit_write   = ext4_writeback_commit_write,
1790         .bmap           = ext4_bmap,
1791         .invalidatepage = ext4_invalidatepage,
1792         .releasepage    = ext4_releasepage,
1793         .direct_IO      = ext4_direct_IO,
1794         .migratepage    = buffer_migrate_page,
1795 };
1796
1797 static const struct address_space_operations ext4_journalled_aops = {
1798         .readpage       = ext4_readpage,
1799         .readpages      = ext4_readpages,
1800         .writepage      = ext4_journalled_writepage,
1801         .sync_page      = block_sync_page,
1802         .prepare_write  = ext4_prepare_write,
1803         .commit_write   = ext4_journalled_commit_write,
1804         .set_page_dirty = ext4_journalled_set_page_dirty,
1805         .bmap           = ext4_bmap,
1806         .invalidatepage = ext4_invalidatepage,
1807         .releasepage    = ext4_releasepage,
1808 };
1809
1810 void ext4_set_aops(struct inode *inode)
1811 {
1812         if (ext4_should_order_data(inode))
1813                 inode->i_mapping->a_ops = &ext4_ordered_aops;
1814         else if (ext4_should_writeback_data(inode))
1815                 inode->i_mapping->a_ops = &ext4_writeback_aops;
1816         else
1817                 inode->i_mapping->a_ops = &ext4_journalled_aops;
1818 }
1819
1820 /*
1821  * ext4_block_truncate_page() zeroes out a mapping from file offset `from'
1822  * up to the end of the block which corresponds to `from'.
1823  * This required during truncate. We need to physically zero the tail end
1824  * of that block so it doesn't yield old data if the file is later grown.
1825  */
1826 int ext4_block_truncate_page(handle_t *handle, struct page *page,
1827                 struct address_space *mapping, loff_t from)
1828 {
1829         ext4_fsblk_t index = from >> PAGE_CACHE_SHIFT;
1830         unsigned offset = from & (PAGE_CACHE_SIZE-1);
1831         unsigned blocksize, iblock, length, pos;
1832         struct inode *inode = mapping->host;
1833         struct buffer_head *bh;
1834         int err = 0;
1835         void *kaddr;
1836
1837         blocksize = inode->i_sb->s_blocksize;
1838         length = blocksize - (offset & (blocksize - 1));
1839         iblock = index << (PAGE_CACHE_SHIFT - inode->i_sb->s_blocksize_bits);
1840
1841         /*
1842          * For "nobh" option,  we can only work if we don't need to
1843          * read-in the page - otherwise we create buffers to do the IO.
1844          */
1845         if (!page_has_buffers(page) && test_opt(inode->i_sb, NOBH) &&
1846              ext4_should_writeback_data(inode) && PageUptodate(page)) {
1847                 kaddr = kmap_atomic(page, KM_USER0);
1848                 memset(kaddr + offset, 0, length);
1849                 flush_dcache_page(page);
1850                 kunmap_atomic(kaddr, KM_USER0);
1851                 set_page_dirty(page);
1852                 goto unlock;
1853         }
1854
1855         if (!page_has_buffers(page))
1856                 create_empty_buffers(page, blocksize, 0);
1857
1858         /* Find the buffer that contains "offset" */
1859         bh = page_buffers(page);
1860         pos = blocksize;
1861         while (offset >= pos) {
1862                 bh = bh->b_this_page;
1863                 iblock++;
1864                 pos += blocksize;
1865         }
1866
1867         err = 0;
1868         if (buffer_freed(bh)) {
1869                 BUFFER_TRACE(bh, "freed: skip");
1870                 goto unlock;
1871         }
1872
1873         if (!buffer_mapped(bh)) {
1874                 BUFFER_TRACE(bh, "unmapped");
1875                 ext4_get_block(inode, iblock, bh, 0);
1876                 /* unmapped? It's a hole - nothing to do */
1877                 if (!buffer_mapped(bh)) {
1878                         BUFFER_TRACE(bh, "still unmapped");
1879                         goto unlock;
1880                 }
1881         }
1882
1883         /* Ok, it's mapped. Make sure it's up-to-date */
1884         if (PageUptodate(page))
1885                 set_buffer_uptodate(bh);
1886
1887         if (!buffer_uptodate(bh)) {
1888                 err = -EIO;
1889                 ll_rw_block(READ, 1, &bh);
1890                 wait_on_buffer(bh);
1891                 /* Uhhuh. Read error. Complain and punt. */
1892                 if (!buffer_uptodate(bh))
1893                         goto unlock;
1894         }
1895
1896         if (ext4_should_journal_data(inode)) {
1897                 BUFFER_TRACE(bh, "get write access");
1898                 err = ext4_journal_get_write_access(handle, bh);
1899                 if (err)
1900                         goto unlock;
1901         }
1902
1903         kaddr = kmap_atomic(page, KM_USER0);
1904         memset(kaddr + offset, 0, length);
1905         flush_dcache_page(page);
1906         kunmap_atomic(kaddr, KM_USER0);
1907
1908         BUFFER_TRACE(bh, "zeroed end of block");
1909
1910         err = 0;
1911         if (ext4_should_journal_data(inode)) {
1912                 err = ext4_journal_dirty_metadata(handle, bh);
1913         } else {
1914                 if (ext4_should_order_data(inode))
1915                         err = ext4_journal_dirty_data(handle, bh);
1916                 mark_buffer_dirty(bh);
1917         }
1918
1919 unlock:
1920         unlock_page(page);
1921         page_cache_release(page);
1922         return err;
1923 }
1924
1925 /*
1926  * Probably it should be a library function... search for first non-zero word
1927  * or memcmp with zero_page, whatever is better for particular architecture.
1928  * Linus?
1929  */
1930 static inline int all_zeroes(__le32 *p, __le32 *q)
1931 {
1932         while (p < q)
1933                 if (*p++)
1934                         return 0;
1935         return 1;
1936 }
1937
1938 /**
1939  *      ext4_find_shared - find the indirect blocks for partial truncation.
1940  *      @inode:   inode in question
1941  *      @depth:   depth of the affected branch
1942  *      @offsets: offsets of pointers in that branch (see ext4_block_to_path)
1943  *      @chain:   place to store the pointers to partial indirect blocks
1944  *      @top:     place to the (detached) top of branch
1945  *
1946  *      This is a helper function used by ext4_truncate().
1947  *
1948  *      When we do truncate() we may have to clean the ends of several
1949  *      indirect blocks but leave the blocks themselves alive. Block is
1950  *      partially truncated if some data below the new i_size is refered
1951  *      from it (and it is on the path to the first completely truncated
1952  *      data block, indeed).  We have to free the top of that path along
1953  *      with everything to the right of the path. Since no allocation
1954  *      past the truncation point is possible until ext4_truncate()
1955  *      finishes, we may safely do the latter, but top of branch may
1956  *      require special attention - pageout below the truncation point
1957  *      might try to populate it.
1958  *
1959  *      We atomically detach the top of branch from the tree, store the
1960  *      block number of its root in *@top, pointers to buffer_heads of
1961  *      partially truncated blocks - in @chain[].bh and pointers to
1962  *      their last elements that should not be removed - in
1963  *      @chain[].p. Return value is the pointer to last filled element
1964  *      of @chain.
1965  *
1966  *      The work left to caller to do the actual freeing of subtrees:
1967  *              a) free the subtree starting from *@top
1968  *              b) free the subtrees whose roots are stored in
1969  *                      (@chain[i].p+1 .. end of @chain[i].bh->b_data)
1970  *              c) free the subtrees growing from the inode past the @chain[0].
1971  *                      (no partially truncated stuff there).  */
1972
1973 static Indirect *ext4_find_shared(struct inode *inode, int depth,
1974                         int offsets[4], Indirect chain[4], __le32 *top)
1975 {
1976         Indirect *partial, *p;
1977         int k, err;
1978
1979         *top = 0;
1980         /* Make k index the deepest non-null offest + 1 */
1981         for (k = depth; k > 1 && !offsets[k-1]; k--)
1982                 ;
1983         partial = ext4_get_branch(inode, k, offsets, chain, &err);
1984         /* Writer: pointers */
1985         if (!partial)
1986                 partial = chain + k-1;
1987         /*
1988          * If the branch acquired continuation since we've looked at it -
1989          * fine, it should all survive and (new) top doesn't belong to us.
1990          */
1991         if (!partial->key && *partial->p)
1992                 /* Writer: end */
1993                 goto no_top;
1994         for (p=partial; p>chain && all_zeroes((__le32*)p->bh->b_data,p->p); p--)
1995                 ;
1996         /*
1997          * OK, we've found the last block that must survive. The rest of our
1998          * branch should be detached before unlocking. However, if that rest
1999          * of branch is all ours and does not grow immediately from the inode
2000          * it's easier to cheat and just decrement partial->p.
2001          */
2002         if (p == chain + k - 1 && p > chain) {
2003                 p->p--;
2004         } else {
2005                 *top = *p->p;
2006                 /* Nope, don't do this in ext4.  Must leave the tree intact */
2007 #if 0
2008                 *p->p = 0;
2009 #endif
2010         }
2011         /* Writer: end */
2012
2013         while(partial > p) {
2014                 brelse(partial->bh);
2015                 partial--;
2016         }
2017 no_top:
2018         return partial;
2019 }
2020
2021 /*
2022  * Zero a number of block pointers in either an inode or an indirect block.
2023  * If we restart the transaction we must again get write access to the
2024  * indirect block for further modification.
2025  *
2026  * We release `count' blocks on disk, but (last - first) may be greater
2027  * than `count' because there can be holes in there.
2028  */
2029 static void ext4_clear_blocks(handle_t *handle, struct inode *inode,
2030                 struct buffer_head *bh, ext4_fsblk_t block_to_free,
2031                 unsigned long count, __le32 *first, __le32 *last)
2032 {
2033         __le32 *p;
2034         if (try_to_extend_transaction(handle, inode)) {
2035                 if (bh) {
2036                         BUFFER_TRACE(bh, "call ext4_journal_dirty_metadata");
2037                         ext4_journal_dirty_metadata(handle, bh);
2038                 }
2039                 ext4_mark_inode_dirty(handle, inode);
2040                 ext4_journal_test_restart(handle, inode);
2041                 if (bh) {
2042                         BUFFER_TRACE(bh, "retaking write access");
2043                         ext4_journal_get_write_access(handle, bh);
2044                 }
2045         }
2046
2047         /*
2048          * Any buffers which are on the journal will be in memory. We find
2049          * them on the hash table so jbd2_journal_revoke() will run jbd2_journal_forget()
2050          * on them.  We've already detached each block from the file, so
2051          * bforget() in jbd2_journal_forget() should be safe.
2052          *
2053          * AKPM: turn on bforget in jbd2_journal_forget()!!!
2054          */
2055         for (p = first; p < last; p++) {
2056                 u32 nr = le32_to_cpu(*p);
2057                 if (nr) {
2058                         struct buffer_head *bh;
2059
2060                         *p = 0;
2061                         bh = sb_find_get_block(inode->i_sb, nr);
2062                         ext4_forget(handle, 0, inode, bh, nr);
2063                 }
2064         }
2065
2066         ext4_free_blocks(handle, inode, block_to_free, count);
2067 }
2068
2069 /**
2070  * ext4_free_data - free a list of data blocks
2071  * @handle:     handle for this transaction
2072  * @inode:      inode we are dealing with
2073  * @this_bh:    indirect buffer_head which contains *@first and *@last
2074  * @first:      array of block numbers
2075  * @last:       points immediately past the end of array
2076  *
2077  * We are freeing all blocks refered from that array (numbers are stored as
2078  * little-endian 32-bit) and updating @inode->i_blocks appropriately.
2079  *
2080  * We accumulate contiguous runs of blocks to free.  Conveniently, if these
2081  * blocks are contiguous then releasing them at one time will only affect one
2082  * or two bitmap blocks (+ group descriptor(s) and superblock) and we won't
2083  * actually use a lot of journal space.
2084  *
2085  * @this_bh will be %NULL if @first and @last point into the inode's direct
2086  * block pointers.
2087  */
2088 static void ext4_free_data(handle_t *handle, struct inode *inode,
2089                            struct buffer_head *this_bh,
2090                            __le32 *first, __le32 *last)
2091 {
2092         ext4_fsblk_t block_to_free = 0;    /* Starting block # of a run */
2093         unsigned long count = 0;            /* Number of blocks in the run */
2094         __le32 *block_to_free_p = NULL;     /* Pointer into inode/ind
2095                                                corresponding to
2096                                                block_to_free */
2097         ext4_fsblk_t nr;                    /* Current block # */
2098         __le32 *p;                          /* Pointer into inode/ind
2099                                                for current block */
2100         int err;
2101
2102         if (this_bh) {                          /* For indirect block */
2103                 BUFFER_TRACE(this_bh, "get_write_access");
2104                 err = ext4_journal_get_write_access(handle, this_bh);
2105                 /* Important: if we can't update the indirect pointers
2106                  * to the blocks, we can't free them. */
2107                 if (err)
2108                         return;
2109         }
2110
2111         for (p = first; p < last; p++) {
2112                 nr = le32_to_cpu(*p);
2113                 if (nr) {
2114                         /* accumulate blocks to free if they're contiguous */
2115                         if (count == 0) {
2116                                 block_to_free = nr;
2117                                 block_to_free_p = p;
2118                                 count = 1;
2119                         } else if (nr == block_to_free + count) {
2120                                 count++;
2121                         } else {
2122                                 ext4_clear_blocks(handle, inode, this_bh,
2123                                                   block_to_free,
2124                                                   count, block_to_free_p, p);
2125                                 block_to_free = nr;
2126                                 block_to_free_p = p;
2127                                 count = 1;
2128                         }
2129                 }
2130         }
2131
2132         if (count > 0)
2133                 ext4_clear_blocks(handle, inode, this_bh, block_to_free,
2134                                   count, block_to_free_p, p);
2135
2136         if (this_bh) {
2137                 BUFFER_TRACE(this_bh, "call ext4_journal_dirty_metadata");
2138                 ext4_journal_dirty_metadata(handle, this_bh);
2139         }
2140 }
2141
2142 /**
2143  *      ext4_free_branches - free an array of branches
2144  *      @handle: JBD handle for this transaction
2145  *      @inode: inode we are dealing with
2146  *      @parent_bh: the buffer_head which contains *@first and *@last
2147  *      @first: array of block numbers
2148  *      @last:  pointer immediately past the end of array
2149  *      @depth: depth of the branches to free
2150  *
2151  *      We are freeing all blocks refered from these branches (numbers are
2152  *      stored as little-endian 32-bit) and updating @inode->i_blocks
2153  *      appropriately.
2154  */
2155 static void ext4_free_branches(handle_t *handle, struct inode *inode,
2156                                struct buffer_head *parent_bh,
2157                                __le32 *first, __le32 *last, int depth)
2158 {
2159         ext4_fsblk_t nr;
2160         __le32 *p;
2161
2162         if (is_handle_aborted(handle))
2163                 return;
2164
2165         if (depth--) {
2166                 struct buffer_head *bh;
2167                 int addr_per_block = EXT4_ADDR_PER_BLOCK(inode->i_sb);
2168                 p = last;
2169                 while (--p >= first) {
2170                         nr = le32_to_cpu(*p);
2171                         if (!nr)
2172                                 continue;               /* A hole */
2173
2174                         /* Go read the buffer for the next level down */
2175                         bh = sb_bread(inode->i_sb, nr);
2176
2177                         /*
2178                          * A read failure? Report error and clear slot
2179                          * (should be rare).
2180                          */
2181                         if (!bh) {
2182                                 ext4_error(inode->i_sb, "ext4_free_branches",
2183                                            "Read failure, inode=%lu, block=%llu",
2184                                            inode->i_ino, nr);
2185                                 continue;
2186                         }
2187
2188                         /* This zaps the entire block.  Bottom up. */
2189                         BUFFER_TRACE(bh, "free child branches");
2190                         ext4_free_branches(handle, inode, bh,
2191                                            (__le32*)bh->b_data,
2192                                            (__le32*)bh->b_data + addr_per_block,
2193                                            depth);
2194
2195                         /*
2196                          * We've probably journalled the indirect block several
2197                          * times during the truncate.  But it's no longer
2198                          * needed and we now drop it from the transaction via
2199                          * jbd2_journal_revoke().
2200                          *
2201                          * That's easy if it's exclusively part of this
2202                          * transaction.  But if it's part of the committing
2203                          * transaction then jbd2_journal_forget() will simply
2204                          * brelse() it.  That means that if the underlying
2205                          * block is reallocated in ext4_get_block(),
2206                          * unmap_underlying_metadata() will find this block
2207                          * and will try to get rid of it.  damn, damn.
2208                          *
2209                          * If this block has already been committed to the
2210                          * journal, a revoke record will be written.  And
2211                          * revoke records must be emitted *before* clearing
2212                          * this block's bit in the bitmaps.
2213                          */
2214                         ext4_forget(handle, 1, inode, bh, bh->b_blocknr);
2215
2216                         /*
2217                          * Everything below this this pointer has been
2218                          * released.  Now let this top-of-subtree go.
2219                          *
2220                          * We want the freeing of this indirect block to be
2221                          * atomic in the journal with the updating of the
2222                          * bitmap block which owns it.  So make some room in
2223                          * the journal.
2224                          *
2225                          * We zero the parent pointer *after* freeing its
2226                          * pointee in the bitmaps, so if extend_transaction()
2227                          * for some reason fails to put the bitmap changes and
2228                          * the release into the same transaction, recovery
2229                          * will merely complain about releasing a free block,
2230                          * rather than leaking blocks.
2231                          */
2232                         if (is_handle_aborted(handle))
2233                                 return;
2234                         if (try_to_extend_transaction(handle, inode)) {
2235                                 ext4_mark_inode_dirty(handle, inode);
2236                                 ext4_journal_test_restart(handle, inode);
2237                         }
2238
2239                         ext4_free_blocks(handle, inode, nr, 1);
2240
2241                         if (parent_bh) {
2242                                 /*
2243                                  * The block which we have just freed is
2244                                  * pointed to by an indirect block: journal it
2245                                  */
2246                                 BUFFER_TRACE(parent_bh, "get_write_access");
2247                                 if (!ext4_journal_get_write_access(handle,
2248                                                                    parent_bh)){
2249                                         *p = 0;
2250                                         BUFFER_TRACE(parent_bh,
2251                                         "call ext4_journal_dirty_metadata");
2252                                         ext4_journal_dirty_metadata(handle,
2253                                                                     parent_bh);
2254                                 }
2255                         }
2256                 }
2257         } else {
2258                 /* We have reached the bottom of the tree. */
2259                 BUFFER_TRACE(parent_bh, "free data blocks");
2260                 ext4_free_data(handle, inode, parent_bh, first, last);
2261         }
2262 }
2263
2264 /*
2265  * ext4_truncate()
2266  *
2267  * We block out ext4_get_block() block instantiations across the entire
2268  * transaction, and VFS/VM ensures that ext4_truncate() cannot run
2269  * simultaneously on behalf of the same inode.
2270  *
2271  * As we work through the truncate and commmit bits of it to the journal there
2272  * is one core, guiding principle: the file's tree must always be consistent on
2273  * disk.  We must be able to restart the truncate after a crash.
2274  *
2275  * The file's tree may be transiently inconsistent in memory (although it
2276  * probably isn't), but whenever we close off and commit a journal transaction,
2277  * the contents of (the filesystem + the journal) must be consistent and
2278  * restartable.  It's pretty simple, really: bottom up, right to left (although
2279  * left-to-right works OK too).
2280  *
2281  * Note that at recovery time, journal replay occurs *before* the restart of
2282  * truncate against the orphan inode list.
2283  *
2284  * The committed inode has the new, desired i_size (which is the same as
2285  * i_disksize in this case).  After a crash, ext4_orphan_cleanup() will see
2286  * that this inode's truncate did not complete and it will again call
2287  * ext4_truncate() to have another go.  So there will be instantiated blocks
2288  * to the right of the truncation point in a crashed ext4 filesystem.  But
2289  * that's fine - as long as they are linked from the inode, the post-crash
2290  * ext4_truncate() run will find them and release them.
2291  */
2292 void ext4_truncate(struct inode *inode)
2293 {
2294         handle_t *handle;
2295         struct ext4_inode_info *ei = EXT4_I(inode);
2296         __le32 *i_data = ei->i_data;
2297         int addr_per_block = EXT4_ADDR_PER_BLOCK(inode->i_sb);
2298         struct address_space *mapping = inode->i_mapping;
2299         int offsets[4];
2300         Indirect chain[4];
2301         Indirect *partial;
2302         __le32 nr = 0;
2303         int n;
2304         long last_block;
2305         unsigned blocksize = inode->i_sb->s_blocksize;
2306         struct page *page;
2307
2308         if (!(S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode) ||
2309             S_ISLNK(inode->i_mode)))
2310                 return;
2311         if (ext4_inode_is_fast_symlink(inode))
2312                 return;
2313         if (IS_APPEND(inode) || IS_IMMUTABLE(inode))
2314                 return;
2315
2316         /*
2317          * We have to lock the EOF page here, because lock_page() nests
2318          * outside jbd2_journal_start().
2319          */
2320         if ((inode->i_size & (blocksize - 1)) == 0) {
2321                 /* Block boundary? Nothing to do */
2322                 page = NULL;
2323         } else {
2324                 page = grab_cache_page(mapping,
2325                                 inode->i_size >> PAGE_CACHE_SHIFT);
2326                 if (!page)
2327                         return;
2328         }
2329
2330         if (EXT4_I(inode)->i_flags & EXT4_EXTENTS_FL)
2331                 return ext4_ext_truncate(inode, page);
2332
2333         handle = start_transaction(inode);
2334         if (IS_ERR(handle)) {
2335                 if (page) {
2336                         clear_highpage(page);
2337                         flush_dcache_page(page);
2338                         unlock_page(page);
2339                         page_cache_release(page);
2340                 }
2341                 return;         /* AKPM: return what? */
2342         }
2343
2344         last_block = (inode->i_size + blocksize-1)
2345                                         >> EXT4_BLOCK_SIZE_BITS(inode->i_sb);
2346
2347         if (page)
2348                 ext4_block_truncate_page(handle, page, mapping, inode->i_size);
2349
2350         n = ext4_block_to_path(inode, last_block, offsets, NULL);
2351         if (n == 0)
2352                 goto out_stop;  /* error */
2353
2354         /*
2355          * OK.  This truncate is going to happen.  We add the inode to the
2356          * orphan list, so that if this truncate spans multiple transactions,
2357          * and we crash, we will resume the truncate when the filesystem
2358          * recovers.  It also marks the inode dirty, to catch the new size.
2359          *
2360          * Implication: the file must always be in a sane, consistent
2361          * truncatable state while each transaction commits.
2362          */
2363         if (ext4_orphan_add(handle, inode))
2364                 goto out_stop;
2365
2366         /*
2367          * The orphan list entry will now protect us from any crash which
2368          * occurs before the truncate completes, so it is now safe to propagate
2369          * the new, shorter inode size (held for now in i_size) into the
2370          * on-disk inode. We do this via i_disksize, which is the value which
2371          * ext4 *really* writes onto the disk inode.
2372          */
2373         ei->i_disksize = inode->i_size;
2374
2375         /*
2376          * From here we block out all ext4_get_block() callers who want to
2377          * modify the block allocation tree.
2378          */
2379         mutex_lock(&ei->truncate_mutex);
2380
2381         if (n == 1) {           /* direct blocks */
2382                 ext4_free_data(handle, inode, NULL, i_data+offsets[0],
2383                                i_data + EXT4_NDIR_BLOCKS);
2384                 goto do_indirects;
2385         }
2386
2387         partial = ext4_find_shared(inode, n, offsets, chain, &nr);
2388         /* Kill the top of shared branch (not detached) */
2389         if (nr) {
2390                 if (partial == chain) {
2391                         /* Shared branch grows from the inode */
2392                         ext4_free_branches(handle, inode, NULL,
2393                                            &nr, &nr+1, (chain+n-1) - partial);
2394                         *partial->p = 0;
2395                         /*
2396                          * We mark the inode dirty prior to restart,
2397                          * and prior to stop.  No need for it here.
2398                          */
2399                 } else {
2400                         /* Shared branch grows from an indirect block */
2401                         BUFFER_TRACE(partial->bh, "get_write_access");
2402                         ext4_free_branches(handle, inode, partial->bh,
2403                                         partial->p,
2404                                         partial->p+1, (chain+n-1) - partial);
2405                 }
2406         }
2407         /* Clear the ends of indirect blocks on the shared branch */
2408         while (partial > chain) {
2409                 ext4_free_branches(handle, inode, partial->bh, partial->p + 1,
2410                                    (__le32*)partial->bh->b_data+addr_per_block,
2411                                    (chain+n-1) - partial);
2412                 BUFFER_TRACE(partial->bh, "call brelse");
2413                 brelse (partial->bh);
2414                 partial--;
2415         }
2416 do_indirects:
2417         /* Kill the remaining (whole) subtrees */
2418         switch (offsets[0]) {
2419         default:
2420                 nr = i_data[EXT4_IND_BLOCK];
2421                 if (nr) {
2422                         ext4_free_branches(handle, inode, NULL, &nr, &nr+1, 1);
2423                         i_data[EXT4_IND_BLOCK] = 0;
2424                 }
2425         case EXT4_IND_BLOCK:
2426                 nr = i_data[EXT4_DIND_BLOCK];
2427                 if (nr) {
2428                         ext4_free_branches(handle, inode, NULL, &nr, &nr+1, 2);
2429                         i_data[EXT4_DIND_BLOCK] = 0;
2430                 }
2431         case EXT4_DIND_BLOCK:
2432                 nr = i_data[EXT4_TIND_BLOCK];
2433                 if (nr) {
2434                         ext4_free_branches(handle, inode, NULL, &nr, &nr+1, 3);
2435                         i_data[EXT4_TIND_BLOCK] = 0;
2436                 }
2437         case EXT4_TIND_BLOCK:
2438                 ;
2439         }
2440
2441         ext4_discard_reservation(inode);
2442
2443         mutex_unlock(&ei->truncate_mutex);
2444         inode->i_mtime = inode->i_ctime = CURRENT_TIME_SEC;
2445         ext4_mark_inode_dirty(handle, inode);
2446
2447         /*
2448          * In a multi-transaction truncate, we only make the final transaction
2449          * synchronous
2450          */
2451         if (IS_SYNC(inode))
2452                 handle->h_sync = 1;
2453 out_stop:
2454         /*
2455          * If this was a simple ftruncate(), and the file will remain alive
2456          * then we need to clear up the orphan record which we created above.
2457          * However, if this was a real unlink then we were called by
2458          * ext4_delete_inode(), and we allow that function to clean up the
2459          * orphan info for us.
2460          */
2461         if (inode->i_nlink)
2462                 ext4_orphan_del(handle, inode);
2463
2464         ext4_journal_stop(handle);
2465 }
2466
2467 static ext4_fsblk_t ext4_get_inode_block(struct super_block *sb,
2468                 unsigned long ino, struct ext4_iloc *iloc)
2469 {
2470         unsigned long desc, group_desc, block_group;
2471         unsigned long offset;
2472         ext4_fsblk_t block;
2473         struct buffer_head *bh;
2474         struct ext4_group_desc * gdp;
2475
2476         if (!ext4_valid_inum(sb, ino)) {
2477                 /*
2478                  * This error is already checked for in namei.c unless we are
2479                  * looking at an NFS filehandle, in which case no error
2480                  * report is needed
2481                  */
2482                 return 0;
2483         }
2484
2485         block_group = (ino - 1) / EXT4_INODES_PER_GROUP(sb);
2486         if (block_group >= EXT4_SB(sb)->s_groups_count) {
2487                 ext4_error(sb,"ext4_get_inode_block","group >= groups count");
2488                 return 0;
2489         }
2490         smp_rmb();
2491         group_desc = block_group >> EXT4_DESC_PER_BLOCK_BITS(sb);
2492         desc = block_group & (EXT4_DESC_PER_BLOCK(sb) - 1);
2493         bh = EXT4_SB(sb)->s_group_desc[group_desc];
2494         if (!bh) {
2495                 ext4_error (sb, "ext4_get_inode_block",
2496                             "Descriptor not loaded");
2497                 return 0;
2498         }
2499
2500         gdp = (struct ext4_group_desc *)((__u8 *)bh->b_data +
2501                 desc * EXT4_DESC_SIZE(sb));
2502         /*
2503          * Figure out the offset within the block group inode table
2504          */
2505         offset = ((ino - 1) % EXT4_INODES_PER_GROUP(sb)) *
2506                 EXT4_INODE_SIZE(sb);
2507         block = ext4_inode_table(sb, gdp) +
2508                 (offset >> EXT4_BLOCK_SIZE_BITS(sb));
2509
2510         iloc->block_group = block_group;
2511         iloc->offset = offset & (EXT4_BLOCK_SIZE(sb) - 1);
2512         return block;
2513 }
2514
2515 /*
2516  * ext4_get_inode_loc returns with an extra refcount against the inode's
2517  * underlying buffer_head on success. If 'in_mem' is true, we have all
2518  * data in memory that is needed to recreate the on-disk version of this
2519  * inode.
2520  */
2521 static int __ext4_get_inode_loc(struct inode *inode,
2522                                 struct ext4_iloc *iloc, int in_mem)
2523 {
2524         ext4_fsblk_t block;
2525         struct buffer_head *bh;
2526
2527         block = ext4_get_inode_block(inode->i_sb, inode->i_ino, iloc);
2528         if (!block)
2529                 return -EIO;
2530
2531         bh = sb_getblk(inode->i_sb, block);
2532         if (!bh) {
2533                 ext4_error (inode->i_sb, "ext4_get_inode_loc",
2534                                 "unable to read inode block - "
2535                                 "inode=%lu, block=%llu",
2536                                  inode->i_ino, block);
2537                 return -EIO;
2538         }
2539         if (!buffer_uptodate(bh)) {
2540                 lock_buffer(bh);
2541                 if (buffer_uptodate(bh)) {
2542                         /* someone brought it uptodate while we waited */
2543                         unlock_buffer(bh);
2544                         goto has_buffer;
2545                 }
2546
2547                 /*
2548                  * If we have all information of the inode in memory and this
2549                  * is the only valid inode in the block, we need not read the
2550                  * block.
2551                  */
2552                 if (in_mem) {
2553                         struct buffer_head *bitmap_bh;
2554                         struct ext4_group_desc *desc;
2555                         int inodes_per_buffer;
2556                         int inode_offset, i;
2557                         int block_group;
2558                         int start;
2559
2560                         block_group = (inode->i_ino - 1) /
2561                                         EXT4_INODES_PER_GROUP(inode->i_sb);
2562                         inodes_per_buffer = bh->b_size /
2563                                 EXT4_INODE_SIZE(inode->i_sb);
2564                         inode_offset = ((inode->i_ino - 1) %
2565                                         EXT4_INODES_PER_GROUP(inode->i_sb));
2566                         start = inode_offset & ~(inodes_per_buffer - 1);
2567
2568                         /* Is the inode bitmap in cache? */
2569                         desc = ext4_get_group_desc(inode->i_sb,
2570                                                 block_group, NULL);
2571                         if (!desc)
2572                                 goto make_io;
2573
2574                         bitmap_bh = sb_getblk(inode->i_sb,
2575                                 ext4_inode_bitmap(inode->i_sb, desc));
2576                         if (!bitmap_bh)
2577                                 goto make_io;
2578
2579                         /*
2580                          * If the inode bitmap isn't in cache then the
2581                          * optimisation may end up performing two reads instead
2582                          * of one, so skip it.
2583                          */
2584                         if (!buffer_uptodate(bitmap_bh)) {
2585                                 brelse(bitmap_bh);
2586                                 goto make_io;
2587                         }
2588                         for (i = start; i < start + inodes_per_buffer; i++) {
2589                                 if (i == inode_offset)
2590                                         continue;
2591                                 if (ext4_test_bit(i, bitmap_bh->b_data))
2592                                         break;
2593                         }
2594                         brelse(bitmap_bh);
2595                         if (i == start + inodes_per_buffer) {
2596                                 /* all other inodes are free, so skip I/O */
2597                                 memset(bh->b_data, 0, bh->b_size);
2598                                 set_buffer_uptodate(bh);
2599                                 unlock_buffer(bh);
2600                                 goto has_buffer;
2601                         }
2602                 }
2603
2604 make_io:
2605                 /*
2606                  * There are other valid inodes in the buffer, this inode
2607                  * has in-inode xattrs, or we don't have this inode in memory.
2608                  * Read the block from disk.
2609                  */
2610                 get_bh(bh);
2611                 bh->b_end_io = end_buffer_read_sync;
2612                 submit_bh(READ_META, bh);
2613                 wait_on_buffer(bh);
2614                 if (!buffer_uptodate(bh)) {
2615                         ext4_error(inode->i_sb, "ext4_get_inode_loc",
2616                                         "unable to read inode block - "
2617                                         "inode=%lu, block=%llu",
2618                                         inode->i_ino, block);
2619                         brelse(bh);
2620                         return -EIO;
2621                 }
2622         }
2623 has_buffer:
2624         iloc->bh = bh;
2625         return 0;
2626 }
2627
2628 int ext4_get_inode_loc(struct inode *inode, struct ext4_iloc *iloc)
2629 {
2630         /* We have all inode data except xattrs in memory here. */
2631         return __ext4_get_inode_loc(inode, iloc,
2632                 !(EXT4_I(inode)->i_state & EXT4_STATE_XATTR));
2633 }
2634
2635 void ext4_set_inode_flags(struct inode *inode)
2636 {
2637         unsigned int flags = EXT4_I(inode)->i_flags;
2638
2639         inode->i_flags &= ~(S_SYNC|S_APPEND|S_IMMUTABLE|S_NOATIME|S_DIRSYNC);
2640         if (flags & EXT4_SYNC_FL)
2641                 inode->i_flags |= S_SYNC;
2642         if (flags & EXT4_APPEND_FL)
2643                 inode->i_flags |= S_APPEND;
2644         if (flags & EXT4_IMMUTABLE_FL)
2645                 inode->i_flags |= S_IMMUTABLE;
2646         if (flags & EXT4_NOATIME_FL)
2647                 inode->i_flags |= S_NOATIME;
2648         if (flags & EXT4_DIRSYNC_FL)
2649                 inode->i_flags |= S_DIRSYNC;
2650 }
2651
2652 void ext4_read_inode(struct inode * inode)
2653 {
2654         struct ext4_iloc iloc;
2655         struct ext4_inode *raw_inode;
2656         struct ext4_inode_info *ei = EXT4_I(inode);
2657         struct buffer_head *bh;
2658         int block;
2659
2660 #ifdef CONFIG_EXT4DEV_FS_POSIX_ACL
2661         ei->i_acl = EXT4_ACL_NOT_CACHED;
2662         ei->i_default_acl = EXT4_ACL_NOT_CACHED;
2663 #endif
2664         ei->i_block_alloc_info = NULL;
2665
2666         if (__ext4_get_inode_loc(inode, &iloc, 0))
2667                 goto bad_inode;
2668         bh = iloc.bh;
2669         raw_inode = ext4_raw_inode(&iloc);
2670         inode->i_mode = le16_to_cpu(raw_inode->i_mode);
2671         inode->i_uid = (uid_t)le16_to_cpu(raw_inode->i_uid_low);
2672         inode->i_gid = (gid_t)le16_to_cpu(raw_inode->i_gid_low);
2673         if(!(test_opt (inode->i_sb, NO_UID32))) {
2674                 inode->i_uid |= le16_to_cpu(raw_inode->i_uid_high) << 16;
2675                 inode->i_gid |= le16_to_cpu(raw_inode->i_gid_high) << 16;
2676         }
2677         inode->i_nlink = le16_to_cpu(raw_inode->i_links_count);
2678         inode->i_size = le32_to_cpu(raw_inode->i_size);
2679         inode->i_atime.tv_sec = le32_to_cpu(raw_inode->i_atime);
2680         inode->i_ctime.tv_sec = le32_to_cpu(raw_inode->i_ctime);
2681         inode->i_mtime.tv_sec = le32_to_cpu(raw_inode->i_mtime);
2682         inode->i_atime.tv_nsec = inode->i_ctime.tv_nsec = inode->i_mtime.tv_nsec = 0;
2683
2684         ei->i_state = 0;
2685         ei->i_dir_start_lookup = 0;
2686         ei->i_dtime = le32_to_cpu(raw_inode->i_dtime);
2687         /* We now have enough fields to check if the inode was active or not.
2688          * This is needed because nfsd might try to access dead inodes
2689          * the test is that same one that e2fsck uses
2690          * NeilBrown 1999oct15
2691          */
2692         if (inode->i_nlink == 0) {
2693                 if (inode->i_mode == 0 ||
2694                     !(EXT4_SB(inode->i_sb)->s_mount_state & EXT4_ORPHAN_FS)) {
2695                         /* this inode is deleted */
2696                         brelse (bh);
2697                         goto bad_inode;
2698                 }
2699                 /* The only unlinked inodes we let through here have
2700                  * valid i_mode and are being read by the orphan
2701                  * recovery code: that's fine, we're about to complete
2702                  * the process of deleting those. */
2703         }
2704         inode->i_blocks = le32_to_cpu(raw_inode->i_blocks);
2705         ei->i_flags = le32_to_cpu(raw_inode->i_flags);
2706 #ifdef EXT4_FRAGMENTS
2707         ei->i_faddr = le32_to_cpu(raw_inode->i_faddr);
2708         ei->i_frag_no = raw_inode->i_frag;
2709         ei->i_frag_size = raw_inode->i_fsize;
2710 #endif
2711         ei->i_file_acl = le32_to_cpu(raw_inode->i_file_acl);
2712         if (EXT4_SB(inode->i_sb)->s_es->s_creator_os !=
2713             cpu_to_le32(EXT4_OS_HURD))
2714                 ei->i_file_acl |=
2715                         ((__u64)le16_to_cpu(raw_inode->i_file_acl_high)) << 32;
2716         if (!S_ISREG(inode->i_mode)) {
2717                 ei->i_dir_acl = le32_to_cpu(raw_inode->i_dir_acl);
2718         } else {
2719                 inode->i_size |=
2720                         ((__u64)le32_to_cpu(raw_inode->i_size_high)) << 32;
2721         }
2722         ei->i_disksize = inode->i_size;
2723         inode->i_generation = le32_to_cpu(raw_inode->i_generation);
2724         ei->i_block_group = iloc.block_group;
2725         /*
2726          * NOTE! The in-memory inode i_data array is in little-endian order
2727          * even on big-endian machines: we do NOT byteswap the block numbers!
2728          */
2729         for (block = 0; block < EXT4_N_BLOCKS; block++)
2730                 ei->i_data[block] = raw_inode->i_block[block];
2731         INIT_LIST_HEAD(&ei->i_orphan);
2732
2733         if (inode->i_ino >= EXT4_FIRST_INO(inode->i_sb) + 1 &&
2734             EXT4_INODE_SIZE(inode->i_sb) > EXT4_GOOD_OLD_INODE_SIZE) {
2735                 /*
2736                  * When mke2fs creates big inodes it does not zero out
2737                  * the unused bytes above EXT4_GOOD_OLD_INODE_SIZE,
2738                  * so ignore those first few inodes.
2739                  */
2740                 ei->i_extra_isize = le16_to_cpu(raw_inode->i_extra_isize);
2741                 if (EXT4_GOOD_OLD_INODE_SIZE + ei->i_extra_isize >
2742                     EXT4_INODE_SIZE(inode->i_sb))
2743                         goto bad_inode;
2744                 if (ei->i_extra_isize == 0) {
2745                         /* The extra space is currently unused. Use it. */
2746                         ei->i_extra_isize = sizeof(struct ext4_inode) -
2747                                             EXT4_GOOD_OLD_INODE_SIZE;
2748                 } else {
2749                         __le32 *magic = (void *)raw_inode +
2750                                         EXT4_GOOD_OLD_INODE_SIZE +
2751                                         ei->i_extra_isize;
2752                         if (*magic == cpu_to_le32(EXT4_XATTR_MAGIC))
2753                                  ei->i_state |= EXT4_STATE_XATTR;
2754                 }
2755         } else
2756                 ei->i_extra_isize = 0;
2757
2758         if (S_ISREG(inode->i_mode)) {
2759                 inode->i_op = &ext4_file_inode_operations;
2760                 inode->i_fop = &ext4_file_operations;
2761                 ext4_set_aops(inode);
2762         } else if (S_ISDIR(inode->i_mode)) {
2763                 inode->i_op = &ext4_dir_inode_operations;
2764                 inode->i_fop = &ext4_dir_operations;
2765         } else if (S_ISLNK(inode->i_mode)) {
2766                 if (ext4_inode_is_fast_symlink(inode))
2767                         inode->i_op = &ext4_fast_symlink_inode_operations;
2768                 else {
2769                         inode->i_op = &ext4_symlink_inode_operations;
2770                         ext4_set_aops(inode);
2771                 }
2772         } else {
2773                 inode->i_op = &ext4_special_inode_operations;
2774                 if (raw_inode->i_block[0])
2775                         init_special_inode(inode, inode->i_mode,
2776                            old_decode_dev(le32_to_cpu(raw_inode->i_block[0])));
2777                 else
2778                         init_special_inode(inode, inode->i_mode,
2779                            new_decode_dev(le32_to_cpu(raw_inode->i_block[1])));
2780         }
2781         brelse (iloc.bh);
2782         ext4_set_inode_flags(inode);
2783         return;
2784
2785 bad_inode:
2786         make_bad_inode(inode);
2787         return;
2788 }
2789
2790 /*
2791  * Post the struct inode info into an on-disk inode location in the
2792  * buffer-cache.  This gobbles the caller's reference to the
2793  * buffer_head in the inode location struct.
2794  *
2795  * The caller must have write access to iloc->bh.
2796  */
2797 static int ext4_do_update_inode(handle_t *handle,
2798                                 struct inode *inode,
2799                                 struct ext4_iloc *iloc)
2800 {
2801         struct ext4_inode *raw_inode = ext4_raw_inode(iloc);
2802         struct ext4_inode_info *ei = EXT4_I(inode);
2803         struct buffer_head *bh = iloc->bh;
2804         int err = 0, rc, block;
2805
2806         /* For fields not not tracking in the in-memory inode,
2807          * initialise them to zero for new inodes. */
2808         if (ei->i_state & EXT4_STATE_NEW)
2809                 memset(raw_inode, 0, EXT4_SB(inode->i_sb)->s_inode_size);
2810
2811         raw_inode->i_mode = cpu_to_le16(inode->i_mode);
2812         if(!(test_opt(inode->i_sb, NO_UID32))) {
2813                 raw_inode->i_uid_low = cpu_to_le16(low_16_bits(inode->i_uid));
2814                 raw_inode->i_gid_low = cpu_to_le16(low_16_bits(inode->i_gid));
2815 /*
2816  * Fix up interoperability with old kernels. Otherwise, old inodes get
2817  * re-used with the upper 16 bits of the uid/gid intact
2818  */
2819                 if(!ei->i_dtime) {
2820                         raw_inode->i_uid_high =
2821                                 cpu_to_le16(high_16_bits(inode->i_uid));
2822                         raw_inode->i_gid_high =
2823                                 cpu_to_le16(high_16_bits(inode->i_gid));
2824                 } else {
2825                         raw_inode->i_uid_high = 0;
2826                         raw_inode->i_gid_high = 0;
2827                 }
2828         } else {
2829                 raw_inode->i_uid_low =
2830                         cpu_to_le16(fs_high2lowuid(inode->i_uid));
2831                 raw_inode->i_gid_low =
2832                         cpu_to_le16(fs_high2lowgid(inode->i_gid));
2833                 raw_inode->i_uid_high = 0;
2834                 raw_inode->i_gid_high = 0;
2835         }
2836         raw_inode->i_links_count = cpu_to_le16(inode->i_nlink);
2837         raw_inode->i_size = cpu_to_le32(ei->i_disksize);
2838         raw_inode->i_atime = cpu_to_le32(inode->i_atime.tv_sec);
2839         raw_inode->i_ctime = cpu_to_le32(inode->i_ctime.tv_sec);
2840         raw_inode->i_mtime = cpu_to_le32(inode->i_mtime.tv_sec);
2841         raw_inode->i_blocks = cpu_to_le32(inode->i_blocks);
2842         raw_inode->i_dtime = cpu_to_le32(ei->i_dtime);
2843         raw_inode->i_flags = cpu_to_le32(ei->i_flags);
2844 #ifdef EXT4_FRAGMENTS
2845         raw_inode->i_faddr = cpu_to_le32(ei->i_faddr);
2846         raw_inode->i_frag = ei->i_frag_no;
2847         raw_inode->i_fsize = ei->i_frag_size;
2848 #endif
2849         if (EXT4_SB(inode->i_sb)->s_es->s_creator_os !=
2850             cpu_to_le32(EXT4_OS_HURD))
2851                 raw_inode->i_file_acl_high =
2852                         cpu_to_le16(ei->i_file_acl >> 32);
2853         raw_inode->i_file_acl = cpu_to_le32(ei->i_file_acl);
2854         if (!S_ISREG(inode->i_mode)) {
2855                 raw_inode->i_dir_acl = cpu_to_le32(ei->i_dir_acl);
2856         } else {
2857                 raw_inode->i_size_high =
2858                         cpu_to_le32(ei->i_disksize >> 32);
2859                 if (ei->i_disksize > 0x7fffffffULL) {
2860                         struct super_block *sb = inode->i_sb;
2861                         if (!EXT4_HAS_RO_COMPAT_FEATURE(sb,
2862                                         EXT4_FEATURE_RO_COMPAT_LARGE_FILE) ||
2863                             EXT4_SB(sb)->s_es->s_rev_level ==
2864                                         cpu_to_le32(EXT4_GOOD_OLD_REV)) {
2865                                /* If this is the first large file
2866                                 * created, add a flag to the superblock.
2867                                 */
2868                                 err = ext4_journal_get_write_access(handle,
2869                                                 EXT4_SB(sb)->s_sbh);
2870                                 if (err)
2871                                         goto out_brelse;
2872                                 ext4_update_dynamic_rev(sb);
2873                                 EXT4_SET_RO_COMPAT_FEATURE(sb,
2874                                         EXT4_FEATURE_RO_COMPAT_LARGE_FILE);
2875                                 sb->s_dirt = 1;
2876                                 handle->h_sync = 1;
2877                                 err = ext4_journal_dirty_metadata(handle,
2878                                                 EXT4_SB(sb)->s_sbh);
2879                         }
2880                 }
2881         }
2882         raw_inode->i_generation = cpu_to_le32(inode->i_generation);
2883         if (S_ISCHR(inode->i_mode) || S_ISBLK(inode->i_mode)) {
2884                 if (old_valid_dev(inode->i_rdev)) {
2885                         raw_inode->i_block[0] =
2886                                 cpu_to_le32(old_encode_dev(inode->i_rdev));
2887                         raw_inode->i_block[1] = 0;
2888                 } else {
2889                         raw_inode->i_block[0] = 0;
2890                         raw_inode->i_block[1] =
2891                                 cpu_to_le32(new_encode_dev(inode->i_rdev));
2892                         raw_inode->i_block[2] = 0;
2893                 }
2894         } else for (block = 0; block < EXT4_N_BLOCKS; block++)
2895                 raw_inode->i_block[block] = ei->i_data[block];
2896
2897         if (ei->i_extra_isize)
2898                 raw_inode->i_extra_isize = cpu_to_le16(ei->i_extra_isize);
2899
2900         BUFFER_TRACE(bh, "call ext4_journal_dirty_metadata");
2901         rc = ext4_journal_dirty_metadata(handle, bh);
2902         if (!err)
2903                 err = rc;
2904         ei->i_state &= ~EXT4_STATE_NEW;
2905
2906 out_brelse:
2907         brelse (bh);
2908         ext4_std_error(inode->i_sb, err);
2909         return err;
2910 }
2911
2912 /*
2913  * ext4_write_inode()
2914  *
2915  * We are called from a few places:
2916  *
2917  * - Within generic_file_write() for O_SYNC files.
2918  *   Here, there will be no transaction running. We wait for any running
2919  *   trasnaction to commit.
2920  *
2921  * - Within sys_sync(), kupdate and such.
2922  *   We wait on commit, if tol to.
2923  *
2924  * - Within prune_icache() (PF_MEMALLOC == true)
2925  *   Here we simply return.  We can't afford to block kswapd on the
2926  *   journal commit.
2927  *
2928  * In all cases it is actually safe for us to return without doing anything,
2929  * because the inode has been copied into a raw inode buffer in
2930  * ext4_mark_inode_dirty().  This is a correctness thing for O_SYNC and for
2931  * knfsd.
2932  *
2933  * Note that we are absolutely dependent upon all inode dirtiers doing the
2934  * right thing: they *must* call mark_inode_dirty() after dirtying info in
2935  * which we are interested.
2936  *
2937  * It would be a bug for them to not do this.  The code:
2938  *
2939  *      mark_inode_dirty(inode)
2940  *      stuff();
2941  *      inode->i_size = expr;
2942  *
2943  * is in error because a kswapd-driven write_inode() could occur while
2944  * `stuff()' is running, and the new i_size will be lost.  Plus the inode
2945  * will no longer be on the superblock's dirty inode list.
2946  */
2947 int ext4_write_inode(struct inode *inode, int wait)
2948 {
2949         if (current->flags & PF_MEMALLOC)
2950                 return 0;
2951
2952         if (ext4_journal_current_handle()) {
2953                 jbd_debug(0, "called recursively, non-PF_MEMALLOC!\n");
2954                 dump_stack();
2955                 return -EIO;
2956         }
2957
2958         if (!wait)
2959                 return 0;
2960
2961         return ext4_force_commit(inode->i_sb);
2962 }
2963
2964 /*
2965  * ext4_setattr()
2966  *
2967  * Called from notify_change.
2968  *
2969  * We want to trap VFS attempts to truncate the file as soon as
2970  * possible.  In particular, we want to make sure that when the VFS
2971  * shrinks i_size, we put the inode on the orphan list and modify
2972  * i_disksize immediately, so that during the subsequent flushing of
2973  * dirty pages and freeing of disk blocks, we can guarantee that any
2974  * commit will leave the blocks being flushed in an unused state on
2975  * disk.  (On recovery, the inode will get truncated and the blocks will
2976  * be freed, so we have a strong guarantee that no future commit will
2977  * leave these blocks visible to the user.)
2978  *
2979  * Called with inode->sem down.
2980  */
2981 int ext4_setattr(struct dentry *dentry, struct iattr *attr)
2982 {
2983         struct inode *inode = dentry->d_inode;
2984         int error, rc = 0;
2985         const unsigned int ia_valid = attr->ia_valid;
2986
2987         error = inode_change_ok(inode, attr);
2988         if (error)
2989                 return error;
2990
2991         if ((ia_valid & ATTR_UID && attr->ia_uid != inode->i_uid) ||
2992                 (ia_valid & ATTR_GID && attr->ia_gid != inode->i_gid)) {
2993                 handle_t *handle;
2994
2995                 /* (user+group)*(old+new) structure, inode write (sb,
2996                  * inode block, ? - but truncate inode update has it) */
2997                 handle = ext4_journal_start(inode, 2*(EXT4_QUOTA_INIT_BLOCKS(inode->i_sb)+
2998                                         EXT4_QUOTA_DEL_BLOCKS(inode->i_sb))+3);
2999                 if (IS_ERR(handle)) {
3000                         error = PTR_ERR(handle);
3001                         goto err_out;
3002                 }
3003                 error = DQUOT_TRANSFER(inode, attr) ? -EDQUOT : 0;
3004                 if (error) {
3005                         ext4_journal_stop(handle);
3006                         return error;
3007                 }
3008                 /* Update corresponding info in inode so that everything is in
3009                  * one transaction */
3010                 if (attr->ia_valid & ATTR_UID)
3011                         inode->i_uid = attr->ia_uid;
3012                 if (attr->ia_valid & ATTR_GID)
3013                         inode->i_gid = attr->ia_gid;
3014                 error = ext4_mark_inode_dirty(handle, inode);
3015                 ext4_journal_stop(handle);
3016         }
3017
3018         if (S_ISREG(inode->i_mode) &&
3019             attr->ia_valid & ATTR_SIZE && attr->ia_size < inode->i_size) {
3020                 handle_t *handle;
3021
3022                 handle = ext4_journal_start(inode, 3);
3023                 if (IS_ERR(handle)) {
3024                         error = PTR_ERR(handle);
3025                         goto err_out;
3026                 }
3027
3028                 error = ext4_orphan_add(handle, inode);
3029                 EXT4_I(inode)->i_disksize = attr->ia_size;
3030                 rc = ext4_mark_inode_dirty(handle, inode);
3031                 if (!error)
3032                         error = rc;
3033                 ext4_journal_stop(handle);
3034         }
3035
3036         rc = inode_setattr(inode, attr);
3037
3038         /* If inode_setattr's call to ext4_truncate failed to get a
3039          * transaction handle at all, we need to clean up the in-core
3040          * orphan list manually. */
3041         if (inode->i_nlink)
3042                 ext4_orphan_del(NULL, inode);
3043
3044         if (!rc && (ia_valid & ATTR_MODE))
3045                 rc = ext4_acl_chmod(inode);
3046
3047 err_out:
3048         ext4_std_error(inode->i_sb, error);
3049         if (!error)
3050                 error = rc;
3051         return error;
3052 }
3053
3054
3055 /*
3056  * How many blocks doth make a writepage()?
3057  *
3058  * With N blocks per page, it may be:
3059  * N data blocks
3060  * 2 indirect block
3061  * 2 dindirect
3062  * 1 tindirect
3063  * N+5 bitmap blocks (from the above)
3064  * N+5 group descriptor summary blocks
3065  * 1 inode block
3066  * 1 superblock.
3067  * 2 * EXT4_SINGLEDATA_TRANS_BLOCKS for the quote files
3068  *
3069  * 3 * (N + 5) + 2 + 2 * EXT4_SINGLEDATA_TRANS_BLOCKS
3070  *
3071  * With ordered or writeback data it's the same, less the N data blocks.
3072  *
3073  * If the inode's direct blocks can hold an integral number of pages then a
3074  * page cannot straddle two indirect blocks, and we can only touch one indirect
3075  * and dindirect block, and the "5" above becomes "3".
3076  *
3077  * This still overestimates under most circumstances.  If we were to pass the
3078  * start and end offsets in here as well we could do block_to_path() on each
3079  * block and work out the exact number of indirects which are touched.  Pah.
3080  */
3081
3082 int ext4_writepage_trans_blocks(struct inode *inode)
3083 {
3084         int bpp = ext4_journal_blocks_per_page(inode);
3085         int indirects = (EXT4_NDIR_BLOCKS % bpp) ? 5 : 3;
3086         int ret;
3087
3088         if (EXT4_I(inode)->i_flags & EXT4_EXTENTS_FL)
3089                 return ext4_ext_writepage_trans_blocks(inode, bpp);
3090
3091         if (ext4_should_journal_data(inode))
3092                 ret = 3 * (bpp + indirects) + 2;
3093         else
3094                 ret = 2 * (bpp + indirects) + 2;
3095
3096 #ifdef CONFIG_QUOTA
3097         /* We know that structure was already allocated during DQUOT_INIT so
3098          * we will be updating only the data blocks + inodes */
3099         ret += 2*EXT4_QUOTA_TRANS_BLOCKS(inode->i_sb);
3100 #endif
3101
3102         return ret;
3103 }
3104
3105 /*
3106  * The caller must have previously called ext4_reserve_inode_write().
3107  * Give this, we know that the caller already has write access to iloc->bh.
3108  */
3109 int ext4_mark_iloc_dirty(handle_t *handle,
3110                 struct inode *inode, struct ext4_iloc *iloc)
3111 {
3112         int err = 0;
3113
3114         /* the do_update_inode consumes one bh->b_count */
3115         get_bh(iloc->bh);
3116
3117         /* ext4_do_update_inode() does jbd2_journal_dirty_metadata */
3118         err = ext4_do_update_inode(handle, inode, iloc);
3119         put_bh(iloc->bh);
3120         return err;
3121 }
3122
3123 /*
3124  * On success, We end up with an outstanding reference count against
3125  * iloc->bh.  This _must_ be cleaned up later.
3126  */
3127
3128 int
3129 ext4_reserve_inode_write(handle_t *handle, struct inode *inode,
3130                          struct ext4_iloc *iloc)
3131 {
3132         int err = 0;
3133         if (handle) {
3134                 err = ext4_get_inode_loc(inode, iloc);
3135                 if (!err) {
3136                         BUFFER_TRACE(iloc->bh, "get_write_access");
3137                         err = ext4_journal_get_write_access(handle, iloc->bh);
3138                         if (err) {
3139                                 brelse(iloc->bh);
3140                                 iloc->bh = NULL;
3141                         }
3142                 }
3143         }
3144         ext4_std_error(inode->i_sb, err);
3145         return err;
3146 }
3147
3148 /*
3149  * What we do here is to mark the in-core inode as clean with respect to inode
3150  * dirtiness (it may still be data-dirty).
3151  * This means that the in-core inode may be reaped by prune_icache
3152  * without having to perform any I/O.  This is a very good thing,
3153  * because *any* task may call prune_icache - even ones which
3154  * have a transaction open against a different journal.
3155  *
3156  * Is this cheating?  Not really.  Sure, we haven't written the
3157  * inode out, but prune_icache isn't a user-visible syncing function.
3158  * Whenever the user wants stuff synced (sys_sync, sys_msync, sys_fsync)
3159  * we start and wait on commits.
3160  *
3161  * Is this efficient/effective?  Well, we're being nice to the system
3162  * by cleaning up our inodes proactively so they can be reaped
3163  * without I/O.  But we are potentially leaving up to five seconds'
3164  * worth of inodes floating about which prune_icache wants us to
3165  * write out.  One way to fix that would be to get prune_icache()
3166  * to do a write_super() to free up some memory.  It has the desired
3167  * effect.
3168  */
3169 int ext4_mark_inode_dirty(handle_t *handle, struct inode *inode)
3170 {
3171         struct ext4_iloc iloc;
3172         int err;
3173
3174         might_sleep();
3175         err = ext4_reserve_inode_write(handle, inode, &iloc);
3176         if (!err)
3177                 err = ext4_mark_iloc_dirty(handle, inode, &iloc);
3178         return err;
3179 }
3180
3181 /*
3182  * ext4_dirty_inode() is called from __mark_inode_dirty()
3183  *
3184  * We're really interested in the case where a file is being extended.
3185  * i_size has been changed by generic_commit_write() and we thus need
3186  * to include the updated inode in the current transaction.
3187  *
3188  * Also, DQUOT_ALLOC_SPACE() will always dirty the inode when blocks
3189  * are allocated to the file.
3190  *
3191  * If the inode is marked synchronous, we don't honour that here - doing
3192  * so would cause a commit on atime updates, which we don't bother doing.
3193  * We handle synchronous inodes at the highest possible level.
3194  */
3195 void ext4_dirty_inode(struct inode *inode)
3196 {
3197         handle_t *current_handle = ext4_journal_current_handle();
3198         handle_t *handle;
3199
3200         handle = ext4_journal_start(inode, 2);
3201         if (IS_ERR(handle))
3202                 goto out;
3203         if (current_handle &&
3204                 current_handle->h_transaction != handle->h_transaction) {
3205                 /* This task has a transaction open against a different fs */
3206                 printk(KERN_EMERG "%s: transactions do not match!\n",
3207                        __FUNCTION__);
3208         } else {
3209                 jbd_debug(5, "marking dirty.  outer handle=%p\n",
3210                                 current_handle);
3211                 ext4_mark_inode_dirty(handle, inode);
3212         }
3213         ext4_journal_stop(handle);
3214 out:
3215         return;
3216 }
3217
3218 #if 0
3219 /*
3220  * Bind an inode's backing buffer_head into this transaction, to prevent
3221  * it from being flushed to disk early.  Unlike
3222  * ext4_reserve_inode_write, this leaves behind no bh reference and
3223  * returns no iloc structure, so the caller needs to repeat the iloc
3224  * lookup to mark the inode dirty later.
3225  */
3226 static int ext4_pin_inode(handle_t *handle, struct inode *inode)
3227 {
3228         struct ext4_iloc iloc;
3229
3230         int err = 0;
3231         if (handle) {
3232                 err = ext4_get_inode_loc(inode, &iloc);
3233                 if (!err) {
3234                         BUFFER_TRACE(iloc.bh, "get_write_access");
3235                         err = jbd2_journal_get_write_access(handle, iloc.bh);
3236                         if (!err)
3237                                 err = ext4_journal_dirty_metadata(handle,
3238                                                                   iloc.bh);
3239                         brelse(iloc.bh);
3240                 }
3241         }
3242         ext4_std_error(inode->i_sb, err);
3243         return err;
3244 }
3245 #endif
3246
3247 int ext4_change_inode_journal_flag(struct inode *inode, int val)
3248 {
3249         journal_t *journal;
3250         handle_t *handle;
3251         int err;
3252
3253         /*
3254          * We have to be very careful here: changing a data block's
3255          * journaling status dynamically is dangerous.  If we write a
3256          * data block to the journal, change the status and then delete
3257          * that block, we risk forgetting to revoke the old log record
3258          * from the journal and so a subsequent replay can corrupt data.
3259          * So, first we make sure that the journal is empty and that
3260          * nobody is changing anything.
3261          */
3262
3263         journal = EXT4_JOURNAL(inode);
3264         if (is_journal_aborted(journal) || IS_RDONLY(inode))
3265                 return -EROFS;
3266
3267         jbd2_journal_lock_updates(journal);
3268         jbd2_journal_flush(journal);
3269
3270         /*
3271          * OK, there are no updates running now, and all cached data is
3272          * synced to disk.  We are now in a completely consistent state
3273          * which doesn't have anything in the journal, and we know that
3274          * no filesystem updates are running, so it is safe to modify
3275          * the inode's in-core data-journaling state flag now.
3276          */
3277
3278         if (val)
3279                 EXT4_I(inode)->i_flags |= EXT4_JOURNAL_DATA_FL;
3280         else
3281                 EXT4_I(inode)->i_flags &= ~EXT4_JOURNAL_DATA_FL;
3282         ext4_set_aops(inode);
3283
3284         jbd2_journal_unlock_updates(journal);
3285
3286         /* Finally we can mark the inode as dirty. */
3287
3288         handle = ext4_journal_start(inode, 1);
3289         if (IS_ERR(handle))
3290                 return PTR_ERR(handle);
3291
3292         err = ext4_mark_inode_dirty(handle, inode);
3293         handle->h_sync = 1;
3294         ext4_journal_stop(handle);
3295         ext4_std_error(inode->i_sb, err);
3296
3297         return err;
3298 }