[PATCH] ext3 filesystem bogus ENOSPC with reservation fix
[linux-2.6] / fs / ext3 / balloc.c
1 /*
2  *  linux/fs/ext3/balloc.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  *  Enhanced block allocation by Stephen Tweedie (sct@redhat.com), 1993
10  *  Big-endian to little-endian byte-swapping/bitmaps by
11  *        David S. Miller (davem@caip.rutgers.edu), 1995
12  */
13
14 #include <linux/time.h>
15 #include <linux/capability.h>
16 #include <linux/fs.h>
17 #include <linux/jbd.h>
18 #include <linux/ext3_fs.h>
19 #include <linux/ext3_jbd.h>
20 #include <linux/quotaops.h>
21 #include <linux/buffer_head.h>
22
23 /*
24  * balloc.c contains the blocks allocation and deallocation routines
25  */
26
27 /*
28  * The free blocks are managed by bitmaps.  A file system contains several
29  * blocks groups.  Each group contains 1 bitmap block for blocks, 1 bitmap
30  * block for inodes, N blocks for the inode table and data blocks.
31  *
32  * The file system contains group descriptors which are located after the
33  * super block.  Each descriptor contains the number of the bitmap block and
34  * the free blocks count in the block.  The descriptors are loaded in memory
35  * when a file system is mounted (see ext3_read_super).
36  */
37
38
39 #define in_range(b, first, len) ((b) >= (first) && (b) <= (first) + (len) - 1)
40
41 struct ext3_group_desc * ext3_get_group_desc(struct super_block * sb,
42                                              unsigned int block_group,
43                                              struct buffer_head ** bh)
44 {
45         unsigned long group_desc;
46         unsigned long offset;
47         struct ext3_group_desc * desc;
48         struct ext3_sb_info *sbi = EXT3_SB(sb);
49
50         if (block_group >= sbi->s_groups_count) {
51                 ext3_error (sb, "ext3_get_group_desc",
52                             "block_group >= groups_count - "
53                             "block_group = %d, groups_count = %lu",
54                             block_group, sbi->s_groups_count);
55
56                 return NULL;
57         }
58         smp_rmb();
59
60         group_desc = block_group >> EXT3_DESC_PER_BLOCK_BITS(sb);
61         offset = block_group & (EXT3_DESC_PER_BLOCK(sb) - 1);
62         if (!sbi->s_group_desc[group_desc]) {
63                 ext3_error (sb, "ext3_get_group_desc",
64                             "Group descriptor not loaded - "
65                             "block_group = %d, group_desc = %lu, desc = %lu",
66                              block_group, group_desc, offset);
67                 return NULL;
68         }
69
70         desc = (struct ext3_group_desc *) sbi->s_group_desc[group_desc]->b_data;
71         if (bh)
72                 *bh = sbi->s_group_desc[group_desc];
73         return desc + offset;
74 }
75
76 /*
77  * Read the bitmap for a given block_group, reading into the specified 
78  * slot in the superblock's bitmap cache.
79  *
80  * Return buffer_head on success or NULL in case of failure.
81  */
82 static struct buffer_head *
83 read_block_bitmap(struct super_block *sb, unsigned int block_group)
84 {
85         struct ext3_group_desc * desc;
86         struct buffer_head * bh = NULL;
87
88         desc = ext3_get_group_desc (sb, block_group, NULL);
89         if (!desc)
90                 goto error_out;
91         bh = sb_bread(sb, le32_to_cpu(desc->bg_block_bitmap));
92         if (!bh)
93                 ext3_error (sb, "read_block_bitmap",
94                             "Cannot read block bitmap - "
95                             "block_group = %d, block_bitmap = %u",
96                             block_group, le32_to_cpu(desc->bg_block_bitmap));
97 error_out:
98         return bh;
99 }
100 /*
101  * The reservation window structure operations
102  * --------------------------------------------
103  * Operations include:
104  * dump, find, add, remove, is_empty, find_next_reservable_window, etc.
105  *
106  * We use sorted double linked list for the per-filesystem reservation
107  * window list. (like in vm_region).
108  *
109  * Initially, we keep those small operations in the abstract functions,
110  * so later if we need a better searching tree than double linked-list,
111  * we could easily switch to that without changing too much
112  * code.
113  */
114 #if 0
115 static void __rsv_window_dump(struct rb_root *root, int verbose,
116                               const char *fn)
117 {
118         struct rb_node *n;
119         struct ext3_reserve_window_node *rsv, *prev;
120         int bad;
121
122 restart:
123         n = rb_first(root);
124         bad = 0;
125         prev = NULL;
126
127         printk("Block Allocation Reservation Windows Map (%s):\n", fn);
128         while (n) {
129                 rsv = list_entry(n, struct ext3_reserve_window_node, rsv_node);
130                 if (verbose)
131                         printk("reservation window 0x%p "
132                                "start:  %d, end:  %d\n",
133                                rsv, rsv->rsv_start, rsv->rsv_end);
134                 if (rsv->rsv_start && rsv->rsv_start >= rsv->rsv_end) {
135                         printk("Bad reservation %p (start >= end)\n",
136                                rsv);
137                         bad = 1;
138                 }
139                 if (prev && prev->rsv_end >= rsv->rsv_start) {
140                         printk("Bad reservation %p (prev->end >= start)\n",
141                                rsv);
142                         bad = 1;
143                 }
144                 if (bad) {
145                         if (!verbose) {
146                                 printk("Restarting reservation walk in verbose mode\n");
147                                 verbose = 1;
148                                 goto restart;
149                         }
150                 }
151                 n = rb_next(n);
152                 prev = rsv;
153         }
154         printk("Window map complete.\n");
155         if (bad)
156                 BUG();
157 }
158 #define rsv_window_dump(root, verbose) \
159         __rsv_window_dump((root), (verbose), __FUNCTION__)
160 #else
161 #define rsv_window_dump(root, verbose) do {} while (0)
162 #endif
163
164 static int
165 goal_in_my_reservation(struct ext3_reserve_window *rsv, ext3_grpblk_t grp_goal,
166                         unsigned int group, struct super_block * sb)
167 {
168         ext3_fsblk_t group_first_block, group_last_block;
169
170         group_first_block = ext3_group_first_block_no(sb, group);
171         group_last_block = group_first_block + EXT3_BLOCKS_PER_GROUP(sb) - 1;
172
173         if ((rsv->_rsv_start > group_last_block) ||
174             (rsv->_rsv_end < group_first_block))
175                 return 0;
176         if ((grp_goal >= 0) && ((grp_goal + group_first_block < rsv->_rsv_start)
177                 || (grp_goal + group_first_block > rsv->_rsv_end)))
178                 return 0;
179         return 1;
180 }
181
182 /*
183  * Find the reserved window which includes the goal, or the previous one
184  * if the goal is not in any window.
185  * Returns NULL if there are no windows or if all windows start after the goal.
186  */
187 static struct ext3_reserve_window_node *
188 search_reserve_window(struct rb_root *root, ext3_fsblk_t goal)
189 {
190         struct rb_node *n = root->rb_node;
191         struct ext3_reserve_window_node *rsv;
192
193         if (!n)
194                 return NULL;
195
196         do {
197                 rsv = rb_entry(n, struct ext3_reserve_window_node, rsv_node);
198
199                 if (goal < rsv->rsv_start)
200                         n = n->rb_left;
201                 else if (goal > rsv->rsv_end)
202                         n = n->rb_right;
203                 else
204                         return rsv;
205         } while (n);
206         /*
207          * We've fallen off the end of the tree: the goal wasn't inside
208          * any particular node.  OK, the previous node must be to one
209          * side of the interval containing the goal.  If it's the RHS,
210          * we need to back up one.
211          */
212         if (rsv->rsv_start > goal) {
213                 n = rb_prev(&rsv->rsv_node);
214                 rsv = rb_entry(n, struct ext3_reserve_window_node, rsv_node);
215         }
216         return rsv;
217 }
218
219 void ext3_rsv_window_add(struct super_block *sb,
220                     struct ext3_reserve_window_node *rsv)
221 {
222         struct rb_root *root = &EXT3_SB(sb)->s_rsv_window_root;
223         struct rb_node *node = &rsv->rsv_node;
224         ext3_fsblk_t start = rsv->rsv_start;
225
226         struct rb_node ** p = &root->rb_node;
227         struct rb_node * parent = NULL;
228         struct ext3_reserve_window_node *this;
229
230         while (*p)
231         {
232                 parent = *p;
233                 this = rb_entry(parent, struct ext3_reserve_window_node, rsv_node);
234
235                 if (start < this->rsv_start)
236                         p = &(*p)->rb_left;
237                 else if (start > this->rsv_end)
238                         p = &(*p)->rb_right;
239                 else
240                         BUG();
241         }
242
243         rb_link_node(node, parent, p);
244         rb_insert_color(node, root);
245 }
246
247 static void rsv_window_remove(struct super_block *sb,
248                               struct ext3_reserve_window_node *rsv)
249 {
250         rsv->rsv_start = EXT3_RESERVE_WINDOW_NOT_ALLOCATED;
251         rsv->rsv_end = EXT3_RESERVE_WINDOW_NOT_ALLOCATED;
252         rsv->rsv_alloc_hit = 0;
253         rb_erase(&rsv->rsv_node, &EXT3_SB(sb)->s_rsv_window_root);
254 }
255
256 static inline int rsv_is_empty(struct ext3_reserve_window *rsv)
257 {
258         /* a valid reservation end block could not be 0 */
259         return (rsv->_rsv_end == EXT3_RESERVE_WINDOW_NOT_ALLOCATED);
260 }
261 void ext3_init_block_alloc_info(struct inode *inode)
262 {
263         struct ext3_inode_info *ei = EXT3_I(inode);
264         struct ext3_block_alloc_info *block_i = ei->i_block_alloc_info;
265         struct super_block *sb = inode->i_sb;
266
267         block_i = kmalloc(sizeof(*block_i), GFP_NOFS);
268         if (block_i) {
269                 struct ext3_reserve_window_node *rsv = &block_i->rsv_window_node;
270
271                 rsv->rsv_start = EXT3_RESERVE_WINDOW_NOT_ALLOCATED;
272                 rsv->rsv_end = EXT3_RESERVE_WINDOW_NOT_ALLOCATED;
273
274                 /*
275                  * if filesystem is mounted with NORESERVATION, the goal
276                  * reservation window size is set to zero to indicate
277                  * block reservation is off
278                  */
279                 if (!test_opt(sb, RESERVATION))
280                         rsv->rsv_goal_size = 0;
281                 else
282                         rsv->rsv_goal_size = EXT3_DEFAULT_RESERVE_BLOCKS;
283                 rsv->rsv_alloc_hit = 0;
284                 block_i->last_alloc_logical_block = 0;
285                 block_i->last_alloc_physical_block = 0;
286         }
287         ei->i_block_alloc_info = block_i;
288 }
289
290 void ext3_discard_reservation(struct inode *inode)
291 {
292         struct ext3_inode_info *ei = EXT3_I(inode);
293         struct ext3_block_alloc_info *block_i = ei->i_block_alloc_info;
294         struct ext3_reserve_window_node *rsv;
295         spinlock_t *rsv_lock = &EXT3_SB(inode->i_sb)->s_rsv_window_lock;
296
297         if (!block_i)
298                 return;
299
300         rsv = &block_i->rsv_window_node;
301         if (!rsv_is_empty(&rsv->rsv_window)) {
302                 spin_lock(rsv_lock);
303                 if (!rsv_is_empty(&rsv->rsv_window))
304                         rsv_window_remove(inode->i_sb, rsv);
305                 spin_unlock(rsv_lock);
306         }
307 }
308
309 /* Free given blocks, update quota and i_blocks field */
310 void ext3_free_blocks_sb(handle_t *handle, struct super_block *sb,
311                          ext3_fsblk_t block, unsigned long count,
312                          unsigned long *pdquot_freed_blocks)
313 {
314         struct buffer_head *bitmap_bh = NULL;
315         struct buffer_head *gd_bh;
316         unsigned long block_group;
317         ext3_grpblk_t bit;
318         unsigned long i;
319         unsigned long overflow;
320         struct ext3_group_desc * desc;
321         struct ext3_super_block * es;
322         struct ext3_sb_info *sbi;
323         int err = 0, ret;
324         ext3_grpblk_t group_freed;
325
326         *pdquot_freed_blocks = 0;
327         sbi = EXT3_SB(sb);
328         es = sbi->s_es;
329         if (block < le32_to_cpu(es->s_first_data_block) ||
330             block + count < block ||
331             block + count > le32_to_cpu(es->s_blocks_count)) {
332                 ext3_error (sb, "ext3_free_blocks",
333                             "Freeing blocks not in datazone - "
334                             "block = "E3FSBLK", count = %lu", block, count);
335                 goto error_return;
336         }
337
338         ext3_debug ("freeing block(s) %lu-%lu\n", block, block + count - 1);
339
340 do_more:
341         overflow = 0;
342         block_group = (block - le32_to_cpu(es->s_first_data_block)) /
343                       EXT3_BLOCKS_PER_GROUP(sb);
344         bit = (block - le32_to_cpu(es->s_first_data_block)) %
345                       EXT3_BLOCKS_PER_GROUP(sb);
346         /*
347          * Check to see if we are freeing blocks across a group
348          * boundary.
349          */
350         if (bit + count > EXT3_BLOCKS_PER_GROUP(sb)) {
351                 overflow = bit + count - EXT3_BLOCKS_PER_GROUP(sb);
352                 count -= overflow;
353         }
354         brelse(bitmap_bh);
355         bitmap_bh = read_block_bitmap(sb, block_group);
356         if (!bitmap_bh)
357                 goto error_return;
358         desc = ext3_get_group_desc (sb, block_group, &gd_bh);
359         if (!desc)
360                 goto error_return;
361
362         if (in_range (le32_to_cpu(desc->bg_block_bitmap), block, count) ||
363             in_range (le32_to_cpu(desc->bg_inode_bitmap), block, count) ||
364             in_range (block, le32_to_cpu(desc->bg_inode_table),
365                       sbi->s_itb_per_group) ||
366             in_range (block + count - 1, le32_to_cpu(desc->bg_inode_table),
367                       sbi->s_itb_per_group))
368                 ext3_error (sb, "ext3_free_blocks",
369                             "Freeing blocks in system zones - "
370                             "Block = "E3FSBLK", count = %lu",
371                             block, count);
372
373         /*
374          * We are about to start releasing blocks in the bitmap,
375          * so we need undo access.
376          */
377         /* @@@ check errors */
378         BUFFER_TRACE(bitmap_bh, "getting undo access");
379         err = ext3_journal_get_undo_access(handle, bitmap_bh);
380         if (err)
381                 goto error_return;
382
383         /*
384          * We are about to modify some metadata.  Call the journal APIs
385          * to unshare ->b_data if a currently-committing transaction is
386          * using it
387          */
388         BUFFER_TRACE(gd_bh, "get_write_access");
389         err = ext3_journal_get_write_access(handle, gd_bh);
390         if (err)
391                 goto error_return;
392
393         jbd_lock_bh_state(bitmap_bh);
394
395         for (i = 0, group_freed = 0; i < count; i++) {
396                 /*
397                  * An HJ special.  This is expensive...
398                  */
399 #ifdef CONFIG_JBD_DEBUG
400                 jbd_unlock_bh_state(bitmap_bh);
401                 {
402                         struct buffer_head *debug_bh;
403                         debug_bh = sb_find_get_block(sb, block + i);
404                         if (debug_bh) {
405                                 BUFFER_TRACE(debug_bh, "Deleted!");
406                                 if (!bh2jh(bitmap_bh)->b_committed_data)
407                                         BUFFER_TRACE(debug_bh,
408                                                 "No commited data in bitmap");
409                                 BUFFER_TRACE2(debug_bh, bitmap_bh, "bitmap");
410                                 __brelse(debug_bh);
411                         }
412                 }
413                 jbd_lock_bh_state(bitmap_bh);
414 #endif
415                 if (need_resched()) {
416                         jbd_unlock_bh_state(bitmap_bh);
417                         cond_resched();
418                         jbd_lock_bh_state(bitmap_bh);
419                 }
420                 /* @@@ This prevents newly-allocated data from being
421                  * freed and then reallocated within the same
422                  * transaction. 
423                  * 
424                  * Ideally we would want to allow that to happen, but to
425                  * do so requires making journal_forget() capable of
426                  * revoking the queued write of a data block, which
427                  * implies blocking on the journal lock.  *forget()
428                  * cannot block due to truncate races.
429                  *
430                  * Eventually we can fix this by making journal_forget()
431                  * return a status indicating whether or not it was able
432                  * to revoke the buffer.  On successful revoke, it is
433                  * safe not to set the allocation bit in the committed
434                  * bitmap, because we know that there is no outstanding
435                  * activity on the buffer any more and so it is safe to
436                  * reallocate it.  
437                  */
438                 BUFFER_TRACE(bitmap_bh, "set in b_committed_data");
439                 J_ASSERT_BH(bitmap_bh,
440                                 bh2jh(bitmap_bh)->b_committed_data != NULL);
441                 ext3_set_bit_atomic(sb_bgl_lock(sbi, block_group), bit + i,
442                                 bh2jh(bitmap_bh)->b_committed_data);
443
444                 /*
445                  * We clear the bit in the bitmap after setting the committed
446                  * data bit, because this is the reverse order to that which
447                  * the allocator uses.
448                  */
449                 BUFFER_TRACE(bitmap_bh, "clear bit");
450                 if (!ext3_clear_bit_atomic(sb_bgl_lock(sbi, block_group),
451                                                 bit + i, bitmap_bh->b_data)) {
452                         jbd_unlock_bh_state(bitmap_bh);
453                         ext3_error(sb, __FUNCTION__,
454                                 "bit already cleared for block "E3FSBLK,
455                                  block + i);
456                         jbd_lock_bh_state(bitmap_bh);
457                         BUFFER_TRACE(bitmap_bh, "bit already cleared");
458                 } else {
459                         group_freed++;
460                 }
461         }
462         jbd_unlock_bh_state(bitmap_bh);
463
464         spin_lock(sb_bgl_lock(sbi, block_group));
465         desc->bg_free_blocks_count =
466                 cpu_to_le16(le16_to_cpu(desc->bg_free_blocks_count) +
467                         group_freed);
468         spin_unlock(sb_bgl_lock(sbi, block_group));
469         percpu_counter_mod(&sbi->s_freeblocks_counter, count);
470
471         /* We dirtied the bitmap block */
472         BUFFER_TRACE(bitmap_bh, "dirtied bitmap block");
473         err = ext3_journal_dirty_metadata(handle, bitmap_bh);
474
475         /* And the group descriptor block */
476         BUFFER_TRACE(gd_bh, "dirtied group descriptor block");
477         ret = ext3_journal_dirty_metadata(handle, gd_bh);
478         if (!err) err = ret;
479         *pdquot_freed_blocks += group_freed;
480
481         if (overflow && !err) {
482                 block += count;
483                 count = overflow;
484                 goto do_more;
485         }
486         sb->s_dirt = 1;
487 error_return:
488         brelse(bitmap_bh);
489         ext3_std_error(sb, err);
490         return;
491 }
492
493 /* Free given blocks, update quota and i_blocks field */
494 void ext3_free_blocks(handle_t *handle, struct inode *inode,
495                         ext3_fsblk_t block, unsigned long count)
496 {
497         struct super_block * sb;
498         unsigned long dquot_freed_blocks;
499
500         sb = inode->i_sb;
501         if (!sb) {
502                 printk ("ext3_free_blocks: nonexistent device");
503                 return;
504         }
505         ext3_free_blocks_sb(handle, sb, block, count, &dquot_freed_blocks);
506         if (dquot_freed_blocks)
507                 DQUOT_FREE_BLOCK(inode, dquot_freed_blocks);
508         return;
509 }
510
511 /*
512  * For ext3 allocations, we must not reuse any blocks which are
513  * allocated in the bitmap buffer's "last committed data" copy.  This
514  * prevents deletes from freeing up the page for reuse until we have
515  * committed the delete transaction.
516  *
517  * If we didn't do this, then deleting something and reallocating it as
518  * data would allow the old block to be overwritten before the
519  * transaction committed (because we force data to disk before commit).
520  * This would lead to corruption if we crashed between overwriting the
521  * data and committing the delete. 
522  *
523  * @@@ We may want to make this allocation behaviour conditional on
524  * data-writes at some point, and disable it for metadata allocations or
525  * sync-data inodes.
526  */
527 static int ext3_test_allocatable(ext3_grpblk_t nr, struct buffer_head *bh)
528 {
529         int ret;
530         struct journal_head *jh = bh2jh(bh);
531
532         if (ext3_test_bit(nr, bh->b_data))
533                 return 0;
534
535         jbd_lock_bh_state(bh);
536         if (!jh->b_committed_data)
537                 ret = 1;
538         else
539                 ret = !ext3_test_bit(nr, jh->b_committed_data);
540         jbd_unlock_bh_state(bh);
541         return ret;
542 }
543
544 static ext3_grpblk_t
545 bitmap_search_next_usable_block(ext3_grpblk_t start, struct buffer_head *bh,
546                                         ext3_grpblk_t maxblocks)
547 {
548         ext3_grpblk_t next;
549         struct journal_head *jh = bh2jh(bh);
550
551         /*
552          * The bitmap search --- search forward alternately through the actual
553          * bitmap and the last-committed copy until we find a bit free in
554          * both
555          */
556         while (start < maxblocks) {
557                 next = ext3_find_next_zero_bit(bh->b_data, maxblocks, start);
558                 if (next >= maxblocks)
559                         return -1;
560                 if (ext3_test_allocatable(next, bh))
561                         return next;
562                 jbd_lock_bh_state(bh);
563                 if (jh->b_committed_data)
564                         start = ext3_find_next_zero_bit(jh->b_committed_data,
565                                                         maxblocks, next);
566                 jbd_unlock_bh_state(bh);
567         }
568         return -1;
569 }
570
571 /*
572  * Find an allocatable block in a bitmap.  We honour both the bitmap and
573  * its last-committed copy (if that exists), and perform the "most
574  * appropriate allocation" algorithm of looking for a free block near
575  * the initial goal; then for a free byte somewhere in the bitmap; then
576  * for any free bit in the bitmap.
577  */
578 static ext3_grpblk_t
579 find_next_usable_block(ext3_grpblk_t start, struct buffer_head *bh,
580                         ext3_grpblk_t maxblocks)
581 {
582         ext3_grpblk_t here, next;
583         char *p, *r;
584
585         if (start > 0) {
586                 /*
587                  * The goal was occupied; search forward for a free 
588                  * block within the next XX blocks.
589                  *
590                  * end_goal is more or less random, but it has to be
591                  * less than EXT3_BLOCKS_PER_GROUP. Aligning up to the
592                  * next 64-bit boundary is simple..
593                  */
594                 ext3_grpblk_t end_goal = (start + 63) & ~63;
595                 if (end_goal > maxblocks)
596                         end_goal = maxblocks;
597                 here = ext3_find_next_zero_bit(bh->b_data, end_goal, start);
598                 if (here < end_goal && ext3_test_allocatable(here, bh))
599                         return here;
600                 ext3_debug("Bit not found near goal\n");
601         }
602
603         here = start;
604         if (here < 0)
605                 here = 0;
606
607         p = ((char *)bh->b_data) + (here >> 3);
608         r = memscan(p, 0, (maxblocks - here + 7) >> 3);
609         next = (r - ((char *)bh->b_data)) << 3;
610
611         if (next < maxblocks && next >= start && ext3_test_allocatable(next, bh))
612                 return next;
613
614         /*
615          * The bitmap search --- search forward alternately through the actual
616          * bitmap and the last-committed copy until we find a bit free in
617          * both
618          */
619         here = bitmap_search_next_usable_block(here, bh, maxblocks);
620         return here;
621 }
622
623 /*
624  * We think we can allocate this block in this bitmap.  Try to set the bit.
625  * If that succeeds then check that nobody has allocated and then freed the
626  * block since we saw that is was not marked in b_committed_data.  If it _was_
627  * allocated and freed then clear the bit in the bitmap again and return
628  * zero (failure).
629  */
630 static inline int
631 claim_block(spinlock_t *lock, ext3_grpblk_t block, struct buffer_head *bh)
632 {
633         struct journal_head *jh = bh2jh(bh);
634         int ret;
635
636         if (ext3_set_bit_atomic(lock, block, bh->b_data))
637                 return 0;
638         jbd_lock_bh_state(bh);
639         if (jh->b_committed_data && ext3_test_bit(block,jh->b_committed_data)) {
640                 ext3_clear_bit_atomic(lock, block, bh->b_data);
641                 ret = 0;
642         } else {
643                 ret = 1;
644         }
645         jbd_unlock_bh_state(bh);
646         return ret;
647 }
648
649 /*
650  * If we failed to allocate the desired block then we may end up crossing to a
651  * new bitmap.  In that case we must release write access to the old one via
652  * ext3_journal_release_buffer(), else we'll run out of credits.
653  */
654 static ext3_grpblk_t
655 ext3_try_to_allocate(struct super_block *sb, handle_t *handle, int group,
656                         struct buffer_head *bitmap_bh, ext3_grpblk_t grp_goal,
657                         unsigned long *count, struct ext3_reserve_window *my_rsv)
658 {
659         ext3_fsblk_t group_first_block;
660         ext3_grpblk_t start, end;
661         unsigned long num = 0;
662
663         /* we do allocation within the reservation window if we have a window */
664         if (my_rsv) {
665                 group_first_block = ext3_group_first_block_no(sb, group);
666                 if (my_rsv->_rsv_start >= group_first_block)
667                         start = my_rsv->_rsv_start - group_first_block;
668                 else
669                         /* reservation window cross group boundary */
670                         start = 0;
671                 end = my_rsv->_rsv_end - group_first_block + 1;
672                 if (end > EXT3_BLOCKS_PER_GROUP(sb))
673                         /* reservation window crosses group boundary */
674                         end = EXT3_BLOCKS_PER_GROUP(sb);
675                 if ((start <= grp_goal) && (grp_goal < end))
676                         start = grp_goal;
677                 else
678                         grp_goal = -1;
679         } else {
680                 if (grp_goal > 0)
681                         start = grp_goal;
682                 else
683                         start = 0;
684                 end = EXT3_BLOCKS_PER_GROUP(sb);
685         }
686
687         BUG_ON(start > EXT3_BLOCKS_PER_GROUP(sb));
688
689 repeat:
690         if (grp_goal < 0 || !ext3_test_allocatable(grp_goal, bitmap_bh)) {
691                 grp_goal = find_next_usable_block(start, bitmap_bh, end);
692                 if (grp_goal < 0)
693                         goto fail_access;
694                 if (!my_rsv) {
695                         int i;
696
697                         for (i = 0; i < 7 && grp_goal > start &&
698                                         ext3_test_allocatable(grp_goal - 1,
699                                                                 bitmap_bh);
700                                         i++, grp_goal--)
701                                 ;
702                 }
703         }
704         start = grp_goal;
705
706         if (!claim_block(sb_bgl_lock(EXT3_SB(sb), group), grp_goal, bitmap_bh)) {
707                 /*
708                  * The block was allocated by another thread, or it was
709                  * allocated and then freed by another thread
710                  */
711                 start++;
712                 grp_goal++;
713                 if (start >= end)
714                         goto fail_access;
715                 goto repeat;
716         }
717         num++;
718         grp_goal++;
719         while (num < *count && grp_goal < end
720                 && ext3_test_allocatable(grp_goal, bitmap_bh)
721                 && claim_block(sb_bgl_lock(EXT3_SB(sb), group), grp_goal, bitmap_bh)) {
722                 num++;
723                 grp_goal++;
724         }
725         *count = num;
726         return grp_goal - num;
727 fail_access:
728         *count = num;
729         return -1;
730 }
731
732 /**
733  *      find_next_reservable_window():
734  *              find a reservable space within the given range.
735  *              It does not allocate the reservation window for now:
736  *              alloc_new_reservation() will do the work later.
737  *
738  *      @search_head: the head of the searching list;
739  *              This is not necessarily the list head of the whole filesystem
740  *
741  *              We have both head and start_block to assist the search
742  *              for the reservable space. The list starts from head,
743  *              but we will shift to the place where start_block is,
744  *              then start from there, when looking for a reservable space.
745  *
746  *      @size: the target new reservation window size
747  *
748  *      @group_first_block: the first block we consider to start
749  *                      the real search from
750  *
751  *      @last_block:
752  *              the maximum block number that our goal reservable space
753  *              could start from. This is normally the last block in this
754  *              group. The search will end when we found the start of next
755  *              possible reservable space is out of this boundary.
756  *              This could handle the cross boundary reservation window
757  *              request.
758  *
759  *      basically we search from the given range, rather than the whole
760  *      reservation double linked list, (start_block, last_block)
761  *      to find a free region that is of my size and has not
762  *      been reserved.
763  *
764  */
765 static int find_next_reservable_window(
766                                 struct ext3_reserve_window_node *search_head,
767                                 struct ext3_reserve_window_node *my_rsv,
768                                 struct super_block * sb,
769                                 ext3_fsblk_t start_block,
770                                 ext3_fsblk_t last_block)
771 {
772         struct rb_node *next;
773         struct ext3_reserve_window_node *rsv, *prev;
774         ext3_fsblk_t cur;
775         int size = my_rsv->rsv_goal_size;
776
777         /* TODO: make the start of the reservation window byte-aligned */
778         /* cur = *start_block & ~7;*/
779         cur = start_block;
780         rsv = search_head;
781         if (!rsv)
782                 return -1;
783
784         while (1) {
785                 if (cur <= rsv->rsv_end)
786                         cur = rsv->rsv_end + 1;
787
788                 /* TODO?
789                  * in the case we could not find a reservable space
790                  * that is what is expected, during the re-search, we could
791                  * remember what's the largest reservable space we could have
792                  * and return that one.
793                  *
794                  * For now it will fail if we could not find the reservable
795                  * space with expected-size (or more)...
796                  */
797                 if (cur > last_block)
798                         return -1;              /* fail */
799
800                 prev = rsv;
801                 next = rb_next(&rsv->rsv_node);
802                 rsv = list_entry(next,struct ext3_reserve_window_node,rsv_node);
803
804                 /*
805                  * Reached the last reservation, we can just append to the
806                  * previous one.
807                  */
808                 if (!next)
809                         break;
810
811                 if (cur + size <= rsv->rsv_start) {
812                         /*
813                          * Found a reserveable space big enough.  We could
814                          * have a reservation across the group boundary here
815                          */
816                         break;
817                 }
818         }
819         /*
820          * we come here either :
821          * when we reach the end of the whole list,
822          * and there is empty reservable space after last entry in the list.
823          * append it to the end of the list.
824          *
825          * or we found one reservable space in the middle of the list,
826          * return the reservation window that we could append to.
827          * succeed.
828          */
829
830         if ((prev != my_rsv) && (!rsv_is_empty(&my_rsv->rsv_window)))
831                 rsv_window_remove(sb, my_rsv);
832
833         /*
834          * Let's book the whole avaliable window for now.  We will check the
835          * disk bitmap later and then, if there are free blocks then we adjust
836          * the window size if it's larger than requested.
837          * Otherwise, we will remove this node from the tree next time
838          * call find_next_reservable_window.
839          */
840         my_rsv->rsv_start = cur;
841         my_rsv->rsv_end = cur + size - 1;
842         my_rsv->rsv_alloc_hit = 0;
843
844         if (prev != my_rsv)
845                 ext3_rsv_window_add(sb, my_rsv);
846
847         return 0;
848 }
849
850 /**
851  *      alloc_new_reservation()--allocate a new reservation window
852  *
853  *              To make a new reservation, we search part of the filesystem
854  *              reservation list (the list that inside the group). We try to
855  *              allocate a new reservation window near the allocation goal,
856  *              or the beginning of the group, if there is no goal.
857  *
858  *              We first find a reservable space after the goal, then from
859  *              there, we check the bitmap for the first free block after
860  *              it. If there is no free block until the end of group, then the
861  *              whole group is full, we failed. Otherwise, check if the free
862  *              block is inside the expected reservable space, if so, we
863  *              succeed.
864  *              If the first free block is outside the reservable space, then
865  *              start from the first free block, we search for next available
866  *              space, and go on.
867  *
868  *      on succeed, a new reservation will be found and inserted into the list
869  *      It contains at least one free block, and it does not overlap with other
870  *      reservation windows.
871  *
872  *      failed: we failed to find a reservation window in this group
873  *
874  *      @rsv: the reservation
875  *
876  *      @grp_goal: The goal (group-relative).  It is where the search for a
877  *              free reservable space should start from.
878  *              if we have a grp_goal(grp_goal >0 ), then start from there,
879  *              no grp_goal(grp_goal = -1), we start from the first block
880  *              of the group.
881  *
882  *      @sb: the super block
883  *      @group: the group we are trying to allocate in
884  *      @bitmap_bh: the block group block bitmap
885  *
886  */
887 static int alloc_new_reservation(struct ext3_reserve_window_node *my_rsv,
888                 ext3_grpblk_t grp_goal, struct super_block *sb,
889                 unsigned int group, struct buffer_head *bitmap_bh)
890 {
891         struct ext3_reserve_window_node *search_head;
892         ext3_fsblk_t group_first_block, group_end_block, start_block;
893         ext3_grpblk_t first_free_block;
894         struct rb_root *fs_rsv_root = &EXT3_SB(sb)->s_rsv_window_root;
895         unsigned long size;
896         int ret;
897         spinlock_t *rsv_lock = &EXT3_SB(sb)->s_rsv_window_lock;
898
899         group_first_block = ext3_group_first_block_no(sb, group);
900         group_end_block = group_first_block + EXT3_BLOCKS_PER_GROUP(sb) - 1;
901
902         if (grp_goal < 0)
903                 start_block = group_first_block;
904         else
905                 start_block = grp_goal + group_first_block;
906
907         size = my_rsv->rsv_goal_size;
908
909         if (!rsv_is_empty(&my_rsv->rsv_window)) {
910                 /*
911                  * if the old reservation is cross group boundary
912                  * and if the goal is inside the old reservation window,
913                  * we will come here when we just failed to allocate from
914                  * the first part of the window. We still have another part
915                  * that belongs to the next group. In this case, there is no
916                  * point to discard our window and try to allocate a new one
917                  * in this group(which will fail). we should
918                  * keep the reservation window, just simply move on.
919                  *
920                  * Maybe we could shift the start block of the reservation
921                  * window to the first block of next group.
922                  */
923
924                 if ((my_rsv->rsv_start <= group_end_block) &&
925                                 (my_rsv->rsv_end > group_end_block) &&
926                                 (start_block >= my_rsv->rsv_start))
927                         return -1;
928
929                 if ((my_rsv->rsv_alloc_hit >
930                      (my_rsv->rsv_end - my_rsv->rsv_start + 1) / 2)) {
931                         /*
932                          * if we previously allocation hit ration is greater than half
933                          * we double the size of reservation window next time
934                          * otherwise keep the same
935                          */
936                         size = size * 2;
937                         if (size > EXT3_MAX_RESERVE_BLOCKS)
938                                 size = EXT3_MAX_RESERVE_BLOCKS;
939                         my_rsv->rsv_goal_size= size;
940                 }
941         }
942
943         spin_lock(rsv_lock);
944         /*
945          * shift the search start to the window near the goal block
946          */
947         search_head = search_reserve_window(fs_rsv_root, start_block);
948
949         /*
950          * find_next_reservable_window() simply finds a reservable window
951          * inside the given range(start_block, group_end_block).
952          *
953          * To make sure the reservation window has a free bit inside it, we
954          * need to check the bitmap after we found a reservable window.
955          */
956 retry:
957         ret = find_next_reservable_window(search_head, my_rsv, sb,
958                                                 start_block, group_end_block);
959
960         if (ret == -1) {
961                 if (!rsv_is_empty(&my_rsv->rsv_window))
962                         rsv_window_remove(sb, my_rsv);
963                 spin_unlock(rsv_lock);
964                 return -1;
965         }
966
967         /*
968          * On success, find_next_reservable_window() returns the
969          * reservation window where there is a reservable space after it.
970          * Before we reserve this reservable space, we need
971          * to make sure there is at least a free block inside this region.
972          *
973          * searching the first free bit on the block bitmap and copy of
974          * last committed bitmap alternatively, until we found a allocatable
975          * block. Search start from the start block of the reservable space
976          * we just found.
977          */
978         spin_unlock(rsv_lock);
979         first_free_block = bitmap_search_next_usable_block(
980                         my_rsv->rsv_start - group_first_block,
981                         bitmap_bh, group_end_block - group_first_block + 1);
982
983         if (first_free_block < 0) {
984                 /*
985                  * no free block left on the bitmap, no point
986                  * to reserve the space. return failed.
987                  */
988                 spin_lock(rsv_lock);
989                 if (!rsv_is_empty(&my_rsv->rsv_window))
990                         rsv_window_remove(sb, my_rsv);
991                 spin_unlock(rsv_lock);
992                 return -1;              /* failed */
993         }
994
995         start_block = first_free_block + group_first_block;
996         /*
997          * check if the first free block is within the
998          * free space we just reserved
999          */
1000         if (start_block >= my_rsv->rsv_start && start_block < my_rsv->rsv_end)
1001                 return 0;               /* success */
1002         /*
1003          * if the first free bit we found is out of the reservable space
1004          * continue search for next reservable space,
1005          * start from where the free block is,
1006          * we also shift the list head to where we stopped last time
1007          */
1008         search_head = my_rsv;
1009         spin_lock(rsv_lock);
1010         goto retry;
1011 }
1012
1013 static void try_to_extend_reservation(struct ext3_reserve_window_node *my_rsv,
1014                         struct super_block *sb, int size)
1015 {
1016         struct ext3_reserve_window_node *next_rsv;
1017         struct rb_node *next;
1018         spinlock_t *rsv_lock = &EXT3_SB(sb)->s_rsv_window_lock;
1019
1020         if (!spin_trylock(rsv_lock))
1021                 return;
1022
1023         next = rb_next(&my_rsv->rsv_node);
1024
1025         if (!next)
1026                 my_rsv->rsv_end += size;
1027         else {
1028                 next_rsv = list_entry(next, struct ext3_reserve_window_node, rsv_node);
1029
1030                 if ((next_rsv->rsv_start - my_rsv->rsv_end - 1) >= size)
1031                         my_rsv->rsv_end += size;
1032                 else
1033                         my_rsv->rsv_end = next_rsv->rsv_start - 1;
1034         }
1035         spin_unlock(rsv_lock);
1036 }
1037
1038 /*
1039  * This is the main function used to allocate a new block and its reservation
1040  * window.
1041  *
1042  * Each time when a new block allocation is need, first try to allocate from
1043  * its own reservation.  If it does not have a reservation window, instead of
1044  * looking for a free bit on bitmap first, then look up the reservation list to
1045  * see if it is inside somebody else's reservation window, we try to allocate a
1046  * reservation window for it starting from the goal first. Then do the block
1047  * allocation within the reservation window.
1048  *
1049  * This will avoid keeping on searching the reservation list again and
1050  * again when somebody is looking for a free block (without
1051  * reservation), and there are lots of free blocks, but they are all
1052  * being reserved.
1053  *
1054  * We use a sorted double linked list for the per-filesystem reservation list.
1055  * The insert, remove and find a free space(non-reserved) operations for the
1056  * sorted double linked list should be fast.
1057  *
1058  */
1059 static ext3_grpblk_t
1060 ext3_try_to_allocate_with_rsv(struct super_block *sb, handle_t *handle,
1061                         unsigned int group, struct buffer_head *bitmap_bh,
1062                         ext3_grpblk_t grp_goal,
1063                         struct ext3_reserve_window_node * my_rsv,
1064                         unsigned long *count, int *errp)
1065 {
1066         ext3_fsblk_t group_first_block;
1067         ext3_grpblk_t ret = 0;
1068         int fatal;
1069         unsigned long num = *count;
1070
1071         *errp = 0;
1072
1073         /*
1074          * Make sure we use undo access for the bitmap, because it is critical
1075          * that we do the frozen_data COW on bitmap buffers in all cases even
1076          * if the buffer is in BJ_Forget state in the committing transaction.
1077          */
1078         BUFFER_TRACE(bitmap_bh, "get undo access for new block");
1079         fatal = ext3_journal_get_undo_access(handle, bitmap_bh);
1080         if (fatal) {
1081                 *errp = fatal;
1082                 return -1;
1083         }
1084
1085         /*
1086          * we don't deal with reservation when
1087          * filesystem is mounted without reservation
1088          * or the file is not a regular file
1089          * or last attempt to allocate a block with reservation turned on failed
1090          */
1091         if (my_rsv == NULL ) {
1092                 ret = ext3_try_to_allocate(sb, handle, group, bitmap_bh,
1093                                                 grp_goal, count, NULL);
1094                 goto out;
1095         }
1096         /*
1097          * grp_goal is a group relative block number (if there is a goal)
1098          * 0 < grp_goal < EXT3_BLOCKS_PER_GROUP(sb)
1099          * first block is a filesystem wide block number
1100          * first block is the block number of the first block in this group
1101          */
1102         group_first_block = ext3_group_first_block_no(sb, group);
1103
1104         /*
1105          * Basically we will allocate a new block from inode's reservation
1106          * window.
1107          *
1108          * We need to allocate a new reservation window, if:
1109          * a) inode does not have a reservation window; or
1110          * b) last attempt to allocate a block from existing reservation
1111          *    failed; or
1112          * c) we come here with a goal and with a reservation window
1113          *
1114          * We do not need to allocate a new reservation window if we come here
1115          * at the beginning with a goal and the goal is inside the window, or
1116          * we don't have a goal but already have a reservation window.
1117          * then we could go to allocate from the reservation window directly.
1118          */
1119         while (1) {
1120                 if (rsv_is_empty(&my_rsv->rsv_window) || (ret < 0) ||
1121                         !goal_in_my_reservation(&my_rsv->rsv_window, grp_goal, group, sb)) {
1122                         if (my_rsv->rsv_goal_size < *count)
1123                                 my_rsv->rsv_goal_size = *count;
1124                         ret = alloc_new_reservation(my_rsv, grp_goal, sb,
1125                                                         group, bitmap_bh);
1126                         if (ret < 0)
1127                                 break;                  /* failed */
1128
1129                         if (!goal_in_my_reservation(&my_rsv->rsv_window, grp_goal, group, sb))
1130                                 grp_goal = -1;
1131                 } else if (grp_goal > 0 && (my_rsv->rsv_end-grp_goal+1) < *count)
1132                         try_to_extend_reservation(my_rsv, sb,
1133                                         *count-my_rsv->rsv_end + grp_goal - 1);
1134
1135                 if ((my_rsv->rsv_start >= group_first_block + EXT3_BLOCKS_PER_GROUP(sb))
1136                     || (my_rsv->rsv_end < group_first_block))
1137                         BUG();
1138                 ret = ext3_try_to_allocate(sb, handle, group, bitmap_bh, grp_goal,
1139                                            &num, &my_rsv->rsv_window);
1140                 if (ret >= 0) {
1141                         my_rsv->rsv_alloc_hit += num;
1142                         *count = num;
1143                         break;                          /* succeed */
1144                 }
1145                 num = *count;
1146         }
1147 out:
1148         if (ret >= 0) {
1149                 BUFFER_TRACE(bitmap_bh, "journal_dirty_metadata for "
1150                                         "bitmap block");
1151                 fatal = ext3_journal_dirty_metadata(handle, bitmap_bh);
1152                 if (fatal) {
1153                         *errp = fatal;
1154                         return -1;
1155                 }
1156                 return ret;
1157         }
1158
1159         BUFFER_TRACE(bitmap_bh, "journal_release_buffer");
1160         ext3_journal_release_buffer(handle, bitmap_bh);
1161         return ret;
1162 }
1163
1164 static int ext3_has_free_blocks(struct ext3_sb_info *sbi)
1165 {
1166         ext3_fsblk_t free_blocks, root_blocks;
1167
1168         free_blocks = percpu_counter_read_positive(&sbi->s_freeblocks_counter);
1169         root_blocks = le32_to_cpu(sbi->s_es->s_r_blocks_count);
1170         if (free_blocks < root_blocks + 1 && !capable(CAP_SYS_RESOURCE) &&
1171                 sbi->s_resuid != current->fsuid &&
1172                 (sbi->s_resgid == 0 || !in_group_p (sbi->s_resgid))) {
1173                 return 0;
1174         }
1175         return 1;
1176 }
1177
1178 /*
1179  * ext3_should_retry_alloc() is called when ENOSPC is returned, and if
1180  * it is profitable to retry the operation, this function will wait
1181  * for the current or commiting transaction to complete, and then
1182  * return TRUE.
1183  */
1184 int ext3_should_retry_alloc(struct super_block *sb, int *retries)
1185 {
1186         if (!ext3_has_free_blocks(EXT3_SB(sb)) || (*retries)++ > 3)
1187                 return 0;
1188
1189         jbd_debug(1, "%s: retrying operation after ENOSPC\n", sb->s_id);
1190
1191         return journal_force_commit_nested(EXT3_SB(sb)->s_journal);
1192 }
1193
1194 /*
1195  * ext3_new_block uses a goal block to assist allocation.  If the goal is
1196  * free, or there is a free block within 32 blocks of the goal, that block
1197  * is allocated.  Otherwise a forward search is made for a free block; within 
1198  * each block group the search first looks for an entire free byte in the block
1199  * bitmap, and then for any free bit if that fails.
1200  * This function also updates quota and i_blocks field.
1201  */
1202 ext3_fsblk_t ext3_new_blocks(handle_t *handle, struct inode *inode,
1203                         ext3_fsblk_t goal, unsigned long *count, int *errp)
1204 {
1205         struct buffer_head *bitmap_bh = NULL;
1206         struct buffer_head *gdp_bh;
1207         int group_no;
1208         int goal_group;
1209         ext3_grpblk_t grp_target_blk;   /* blockgroup relative goal block */
1210         ext3_grpblk_t grp_alloc_blk;    /* blockgroup-relative allocated block*/
1211         ext3_fsblk_t ret_block;         /* filesyetem-wide allocated block */
1212         int bgi;                        /* blockgroup iteration index */
1213         int fatal = 0, err;
1214         int performed_allocation = 0;
1215         ext3_grpblk_t free_blocks;      /* number of free blocks in a group */
1216         struct super_block *sb;
1217         struct ext3_group_desc *gdp;
1218         struct ext3_super_block *es;
1219         struct ext3_sb_info *sbi;
1220         struct ext3_reserve_window_node *my_rsv = NULL;
1221         struct ext3_block_alloc_info *block_i;
1222         unsigned short windowsz = 0;
1223 #ifdef EXT3FS_DEBUG
1224         static int goal_hits, goal_attempts;
1225 #endif
1226         unsigned long ngroups;
1227         unsigned long num = *count;
1228
1229         *errp = -ENOSPC;
1230         sb = inode->i_sb;
1231         if (!sb) {
1232                 printk("ext3_new_block: nonexistent device");
1233                 return 0;
1234         }
1235
1236         /*
1237          * Check quota for allocation of this block.
1238          */
1239         if (DQUOT_ALLOC_BLOCK(inode, num)) {
1240                 *errp = -EDQUOT;
1241                 return 0;
1242         }
1243
1244         sbi = EXT3_SB(sb);
1245         es = EXT3_SB(sb)->s_es;
1246         ext3_debug("goal=%lu.\n", goal);
1247         /*
1248          * Allocate a block from reservation only when
1249          * filesystem is mounted with reservation(default,-o reservation), and
1250          * it's a regular file, and
1251          * the desired window size is greater than 0 (One could use ioctl
1252          * command EXT3_IOC_SETRSVSZ to set the window size to 0 to turn off
1253          * reservation on that particular file)
1254          */
1255         block_i = EXT3_I(inode)->i_block_alloc_info;
1256         if (block_i && ((windowsz = block_i->rsv_window_node.rsv_goal_size) > 0))
1257                 my_rsv = &block_i->rsv_window_node;
1258
1259         if (!ext3_has_free_blocks(sbi)) {
1260                 *errp = -ENOSPC;
1261                 goto out;
1262         }
1263
1264         /*
1265          * First, test whether the goal block is free.
1266          */
1267         if (goal < le32_to_cpu(es->s_first_data_block) ||
1268             goal >= le32_to_cpu(es->s_blocks_count))
1269                 goal = le32_to_cpu(es->s_first_data_block);
1270         group_no = (goal - le32_to_cpu(es->s_first_data_block)) /
1271                         EXT3_BLOCKS_PER_GROUP(sb);
1272         goal_group = group_no;
1273 retry_alloc:
1274         gdp = ext3_get_group_desc(sb, group_no, &gdp_bh);
1275         if (!gdp)
1276                 goto io_error;
1277
1278         free_blocks = le16_to_cpu(gdp->bg_free_blocks_count);
1279         /*
1280          * if there is not enough free blocks to make a new resevation
1281          * turn off reservation for this allocation
1282          */
1283         if (my_rsv && (free_blocks < windowsz)
1284                 && (rsv_is_empty(&my_rsv->rsv_window)))
1285                 my_rsv = NULL;
1286
1287         if (free_blocks > 0) {
1288                 grp_target_blk = ((goal - le32_to_cpu(es->s_first_data_block)) %
1289                                 EXT3_BLOCKS_PER_GROUP(sb));
1290                 bitmap_bh = read_block_bitmap(sb, group_no);
1291                 if (!bitmap_bh)
1292                         goto io_error;
1293                 grp_alloc_blk = ext3_try_to_allocate_with_rsv(sb, handle,
1294                                         group_no, bitmap_bh, grp_target_blk,
1295                                         my_rsv, &num, &fatal);
1296                 if (fatal)
1297                         goto out;
1298                 if (grp_alloc_blk >= 0)
1299                         goto allocated;
1300         }
1301
1302         ngroups = EXT3_SB(sb)->s_groups_count;
1303         smp_rmb();
1304
1305         /*
1306          * Now search the rest of the groups.  We assume that 
1307          * i and gdp correctly point to the last group visited.
1308          */
1309         for (bgi = 0; bgi < ngroups; bgi++) {
1310                 group_no++;
1311                 if (group_no >= ngroups)
1312                         group_no = 0;
1313                 gdp = ext3_get_group_desc(sb, group_no, &gdp_bh);
1314                 if (!gdp) {
1315                         *errp = -EIO;
1316                         goto out;
1317                 }
1318                 free_blocks = le16_to_cpu(gdp->bg_free_blocks_count);
1319                 /*
1320                  * skip this group if the number of
1321                  * free blocks is less than half of the reservation
1322                  * window size.
1323                  */
1324                 if (free_blocks <= (windowsz/2))
1325                         continue;
1326
1327                 brelse(bitmap_bh);
1328                 bitmap_bh = read_block_bitmap(sb, group_no);
1329                 if (!bitmap_bh)
1330                         goto io_error;
1331                 /*
1332                  * try to allocate block(s) from this group, without a goal(-1).
1333                  */
1334                 grp_alloc_blk = ext3_try_to_allocate_with_rsv(sb, handle,
1335                                         group_no, bitmap_bh, -1, my_rsv,
1336                                         &num, &fatal);
1337                 if (fatal)
1338                         goto out;
1339                 if (grp_alloc_blk >= 0)
1340                         goto allocated;
1341         }
1342         /*
1343          * We may end up a bogus ealier ENOSPC error due to
1344          * filesystem is "full" of reservations, but
1345          * there maybe indeed free blocks avaliable on disk
1346          * In this case, we just forget about the reservations
1347          * just do block allocation as without reservations.
1348          */
1349         if (my_rsv) {
1350                 my_rsv = NULL;
1351                 group_no = goal_group;
1352                 goto retry_alloc;
1353         }
1354         /* No space left on the device */
1355         *errp = -ENOSPC;
1356         goto out;
1357
1358 allocated:
1359
1360         ext3_debug("using block group %d(%d)\n",
1361                         group_no, gdp->bg_free_blocks_count);
1362
1363         BUFFER_TRACE(gdp_bh, "get_write_access");
1364         fatal = ext3_journal_get_write_access(handle, gdp_bh);
1365         if (fatal)
1366                 goto out;
1367
1368         ret_block = grp_alloc_blk + ext3_group_first_block_no(sb, group_no);
1369
1370         if (in_range(le32_to_cpu(gdp->bg_block_bitmap), ret_block, num) ||
1371             in_range(le32_to_cpu(gdp->bg_inode_bitmap), ret_block, num) ||
1372             in_range(ret_block, le32_to_cpu(gdp->bg_inode_table),
1373                       EXT3_SB(sb)->s_itb_per_group) ||
1374             in_range(ret_block + num - 1, le32_to_cpu(gdp->bg_inode_table),
1375                       EXT3_SB(sb)->s_itb_per_group))
1376                 ext3_error(sb, "ext3_new_block",
1377                             "Allocating block in system zone - "
1378                             "blocks from "E3FSBLK", length %lu",
1379                              ret_block, num);
1380
1381         performed_allocation = 1;
1382
1383 #ifdef CONFIG_JBD_DEBUG
1384         {
1385                 struct buffer_head *debug_bh;
1386
1387                 /* Record bitmap buffer state in the newly allocated block */
1388                 debug_bh = sb_find_get_block(sb, ret_block);
1389                 if (debug_bh) {
1390                         BUFFER_TRACE(debug_bh, "state when allocated");
1391                         BUFFER_TRACE2(debug_bh, bitmap_bh, "bitmap state");
1392                         brelse(debug_bh);
1393                 }
1394         }
1395         jbd_lock_bh_state(bitmap_bh);
1396         spin_lock(sb_bgl_lock(sbi, group_no));
1397         if (buffer_jbd(bitmap_bh) && bh2jh(bitmap_bh)->b_committed_data) {
1398                 int i;
1399
1400                 for (i = 0; i < num; i++) {
1401                         if (ext3_test_bit(grp_alloc_blk+i,
1402                                         bh2jh(bitmap_bh)->b_committed_data)) {
1403                                 printk("%s: block was unexpectedly set in "
1404                                         "b_committed_data\n", __FUNCTION__);
1405                         }
1406                 }
1407         }
1408         ext3_debug("found bit %d\n", grp_alloc_blk);
1409         spin_unlock(sb_bgl_lock(sbi, group_no));
1410         jbd_unlock_bh_state(bitmap_bh);
1411 #endif
1412
1413         if (ret_block + num - 1 >= le32_to_cpu(es->s_blocks_count)) {
1414                 ext3_error(sb, "ext3_new_block",
1415                             "block("E3FSBLK") >= blocks count(%d) - "
1416                             "block_group = %d, es == %p ", ret_block,
1417                         le32_to_cpu(es->s_blocks_count), group_no, es);
1418                 goto out;
1419         }
1420
1421         /*
1422          * It is up to the caller to add the new buffer to a journal
1423          * list of some description.  We don't know in advance whether
1424          * the caller wants to use it as metadata or data.
1425          */
1426         ext3_debug("allocating block %lu. Goal hits %d of %d.\n",
1427                         ret_block, goal_hits, goal_attempts);
1428
1429         spin_lock(sb_bgl_lock(sbi, group_no));
1430         gdp->bg_free_blocks_count =
1431                         cpu_to_le16(le16_to_cpu(gdp->bg_free_blocks_count) - num);
1432         spin_unlock(sb_bgl_lock(sbi, group_no));
1433         percpu_counter_mod(&sbi->s_freeblocks_counter, -num);
1434
1435         BUFFER_TRACE(gdp_bh, "journal_dirty_metadata for group descriptor");
1436         err = ext3_journal_dirty_metadata(handle, gdp_bh);
1437         if (!fatal)
1438                 fatal = err;
1439
1440         sb->s_dirt = 1;
1441         if (fatal)
1442                 goto out;
1443
1444         *errp = 0;
1445         brelse(bitmap_bh);
1446         DQUOT_FREE_BLOCK(inode, *count-num);
1447         *count = num;
1448         return ret_block;
1449
1450 io_error:
1451         *errp = -EIO;
1452 out:
1453         if (fatal) {
1454                 *errp = fatal;
1455                 ext3_std_error(sb, fatal);
1456         }
1457         /*
1458          * Undo the block allocation
1459          */
1460         if (!performed_allocation)
1461                 DQUOT_FREE_BLOCK(inode, *count);
1462         brelse(bitmap_bh);
1463         return 0;
1464 }
1465
1466 ext3_fsblk_t ext3_new_block(handle_t *handle, struct inode *inode,
1467                         ext3_fsblk_t goal, int *errp)
1468 {
1469         unsigned long count = 1;
1470
1471         return ext3_new_blocks(handle, inode, goal, &count, errp);
1472 }
1473
1474 ext3_fsblk_t ext3_count_free_blocks(struct super_block *sb)
1475 {
1476         ext3_fsblk_t desc_count;
1477         struct ext3_group_desc *gdp;
1478         int i;
1479         unsigned long ngroups = EXT3_SB(sb)->s_groups_count;
1480 #ifdef EXT3FS_DEBUG
1481         struct ext3_super_block *es;
1482         ext3_fsblk_t bitmap_count;
1483         unsigned long x;
1484         struct buffer_head *bitmap_bh = NULL;
1485
1486         es = EXT3_SB(sb)->s_es;
1487         desc_count = 0;
1488         bitmap_count = 0;
1489         gdp = NULL;
1490
1491         smp_rmb();
1492         for (i = 0; i < ngroups; i++) {
1493                 gdp = ext3_get_group_desc(sb, i, NULL);
1494                 if (!gdp)
1495                         continue;
1496                 desc_count += le16_to_cpu(gdp->bg_free_blocks_count);
1497                 brelse(bitmap_bh);
1498                 bitmap_bh = read_block_bitmap(sb, i);
1499                 if (bitmap_bh == NULL)
1500                         continue;
1501
1502                 x = ext3_count_free(bitmap_bh, sb->s_blocksize);
1503                 printk("group %d: stored = %d, counted = %lu\n",
1504                         i, le16_to_cpu(gdp->bg_free_blocks_count), x);
1505                 bitmap_count += x;
1506         }
1507         brelse(bitmap_bh);
1508         printk("ext3_count_free_blocks: stored = "E3FSBLK
1509                 ", computed = "E3FSBLK", "E3FSBLK"\n",
1510                le32_to_cpu(es->s_free_blocks_count),
1511                 desc_count, bitmap_count);
1512         return bitmap_count;
1513 #else
1514         desc_count = 0;
1515         smp_rmb();
1516         for (i = 0; i < ngroups; i++) {
1517                 gdp = ext3_get_group_desc(sb, i, NULL);
1518                 if (!gdp)
1519                         continue;
1520                 desc_count += le16_to_cpu(gdp->bg_free_blocks_count);
1521         }
1522
1523         return desc_count;
1524 #endif
1525 }
1526
1527 static inline int
1528 block_in_use(ext3_fsblk_t block, struct super_block *sb, unsigned char *map)
1529 {
1530         return ext3_test_bit ((block -
1531                 le32_to_cpu(EXT3_SB(sb)->s_es->s_first_data_block)) %
1532                          EXT3_BLOCKS_PER_GROUP(sb), map);
1533 }
1534
1535 static inline int test_root(int a, int b)
1536 {
1537         int num = b;
1538
1539         while (a > num)
1540                 num *= b;
1541         return num == a;
1542 }
1543
1544 static int ext3_group_sparse(int group)
1545 {
1546         if (group <= 1)
1547                 return 1;
1548         if (!(group & 1))
1549                 return 0;
1550         return (test_root(group, 7) || test_root(group, 5) ||
1551                 test_root(group, 3));
1552 }
1553
1554 /**
1555  *      ext3_bg_has_super - number of blocks used by the superblock in group
1556  *      @sb: superblock for filesystem
1557  *      @group: group number to check
1558  *
1559  *      Return the number of blocks used by the superblock (primary or backup)
1560  *      in this group.  Currently this will be only 0 or 1.
1561  */
1562 int ext3_bg_has_super(struct super_block *sb, int group)
1563 {
1564         if (EXT3_HAS_RO_COMPAT_FEATURE(sb,
1565                                 EXT3_FEATURE_RO_COMPAT_SPARSE_SUPER) &&
1566                         !ext3_group_sparse(group))
1567                 return 0;
1568         return 1;
1569 }
1570
1571 static unsigned long ext3_bg_num_gdb_meta(struct super_block *sb, int group)
1572 {
1573         unsigned long metagroup = group / EXT3_DESC_PER_BLOCK(sb);
1574         unsigned long first = metagroup * EXT3_DESC_PER_BLOCK(sb);
1575         unsigned long last = first + EXT3_DESC_PER_BLOCK(sb) - 1;
1576
1577         if (group == first || group == first + 1 || group == last)
1578                 return 1;
1579         return 0;
1580 }
1581
1582 static unsigned long ext3_bg_num_gdb_nometa(struct super_block *sb, int group)
1583 {
1584         if (EXT3_HAS_RO_COMPAT_FEATURE(sb,
1585                                 EXT3_FEATURE_RO_COMPAT_SPARSE_SUPER) &&
1586                         !ext3_group_sparse(group))
1587                 return 0;
1588         return EXT3_SB(sb)->s_gdb_count;
1589 }
1590
1591 /**
1592  *      ext3_bg_num_gdb - number of blocks used by the group table in group
1593  *      @sb: superblock for filesystem
1594  *      @group: group number to check
1595  *
1596  *      Return the number of blocks used by the group descriptor table
1597  *      (primary or backup) in this group.  In the future there may be a
1598  *      different number of descriptor blocks in each group.
1599  */
1600 unsigned long ext3_bg_num_gdb(struct super_block *sb, int group)
1601 {
1602         unsigned long first_meta_bg =
1603                         le32_to_cpu(EXT3_SB(sb)->s_es->s_first_meta_bg);
1604         unsigned long metagroup = group / EXT3_DESC_PER_BLOCK(sb);
1605
1606         if (!EXT3_HAS_INCOMPAT_FEATURE(sb,EXT3_FEATURE_INCOMPAT_META_BG) ||
1607                         metagroup < first_meta_bg)
1608                 return ext3_bg_num_gdb_nometa(sb,group);
1609
1610         return ext3_bg_num_gdb_meta(sb,group);
1611
1612 }