Merge git://oss.sgi.com:8090/oss/git/xfs-2.6
[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/config.h>
15 #include <linux/time.h>
16 #include <linux/capability.h>
17 #include <linux/fs.h>
18 #include <linux/jbd.h>
19 #include <linux/ext3_fs.h>
20 #include <linux/ext3_jbd.h>
21 #include <linux/quotaops.h>
22 #include <linux/buffer_head.h>
23
24 /*
25  * balloc.c contains the blocks allocation and deallocation routines
26  */
27
28 /*
29  * The free blocks are managed by bitmaps.  A file system contains several
30  * blocks groups.  Each group contains 1 bitmap block for blocks, 1 bitmap
31  * block for inodes, N blocks for the inode table and data blocks.
32  *
33  * The file system contains group descriptors which are located after the
34  * super block.  Each descriptor contains the number of the bitmap block and
35  * the free blocks count in the block.  The descriptors are loaded in memory
36  * when a file system is mounted (see ext3_read_super).
37  */
38
39
40 #define in_range(b, first, len) ((b) >= (first) && (b) <= (first) + (len) - 1)
41
42 struct ext3_group_desc * ext3_get_group_desc(struct super_block * sb,
43                                              unsigned int block_group,
44                                              struct buffer_head ** bh)
45 {
46         unsigned long group_desc;
47         unsigned long offset;
48         struct ext3_group_desc * desc;
49         struct ext3_sb_info *sbi = EXT3_SB(sb);
50
51         if (block_group >= sbi->s_groups_count) {
52                 ext3_error (sb, "ext3_get_group_desc",
53                             "block_group >= groups_count - "
54                             "block_group = %d, groups_count = %lu",
55                             block_group, sbi->s_groups_count);
56
57                 return NULL;
58         }
59         smp_rmb();
60
61         group_desc = block_group >> EXT3_DESC_PER_BLOCK_BITS(sb);
62         offset = block_group & (EXT3_DESC_PER_BLOCK(sb) - 1);
63         if (!sbi->s_group_desc[group_desc]) {
64                 ext3_error (sb, "ext3_get_group_desc",
65                             "Group descriptor not loaded - "
66                             "block_group = %d, group_desc = %lu, desc = %lu",
67                              block_group, group_desc, offset);
68                 return NULL;
69         }
70
71         desc = (struct ext3_group_desc *) sbi->s_group_desc[group_desc]->b_data;
72         if (bh)
73                 *bh = sbi->s_group_desc[group_desc];
74         return desc + offset;
75 }
76
77 /*
78  * Read the bitmap for a given block_group, reading into the specified 
79  * slot in the superblock's bitmap cache.
80  *
81  * Return buffer_head on success or NULL in case of failure.
82  */
83 static struct buffer_head *
84 read_block_bitmap(struct super_block *sb, unsigned int block_group)
85 {
86         struct ext3_group_desc * desc;
87         struct buffer_head * bh = NULL;
88
89         desc = ext3_get_group_desc (sb, block_group, NULL);
90         if (!desc)
91                 goto error_out;
92         bh = sb_bread(sb, le32_to_cpu(desc->bg_block_bitmap));
93         if (!bh)
94                 ext3_error (sb, "read_block_bitmap",
95                             "Cannot read block bitmap - "
96                             "block_group = %d, block_bitmap = %u",
97                             block_group, le32_to_cpu(desc->bg_block_bitmap));
98 error_out:
99         return bh;
100 }
101 /*
102  * The reservation window structure operations
103  * --------------------------------------------
104  * Operations include:
105  * dump, find, add, remove, is_empty, find_next_reservable_window, etc.
106  *
107  * We use sorted double linked list for the per-filesystem reservation
108  * window list. (like in vm_region).
109  *
110  * Initially, we keep those small operations in the abstract functions,
111  * so later if we need a better searching tree than double linked-list,
112  * we could easily switch to that without changing too much
113  * code.
114  */
115 #if 0
116 static void __rsv_window_dump(struct rb_root *root, int verbose,
117                               const char *fn)
118 {
119         struct rb_node *n;
120         struct ext3_reserve_window_node *rsv, *prev;
121         int bad;
122
123 restart:
124         n = rb_first(root);
125         bad = 0;
126         prev = NULL;
127
128         printk("Block Allocation Reservation Windows Map (%s):\n", fn);
129         while (n) {
130                 rsv = list_entry(n, struct ext3_reserve_window_node, rsv_node);
131                 if (verbose)
132                         printk("reservation window 0x%p "
133                                "start:  %d, end:  %d\n",
134                                rsv, rsv->rsv_start, rsv->rsv_end);
135                 if (rsv->rsv_start && rsv->rsv_start >= rsv->rsv_end) {
136                         printk("Bad reservation %p (start >= end)\n",
137                                rsv);
138                         bad = 1;
139                 }
140                 if (prev && prev->rsv_end >= rsv->rsv_start) {
141                         printk("Bad reservation %p (prev->end >= start)\n",
142                                rsv);
143                         bad = 1;
144                 }
145                 if (bad) {
146                         if (!verbose) {
147                                 printk("Restarting reservation walk in verbose mode\n");
148                                 verbose = 1;
149                                 goto restart;
150                         }
151                 }
152                 n = rb_next(n);
153                 prev = rsv;
154         }
155         printk("Window map complete.\n");
156         if (bad)
157                 BUG();
158 }
159 #define rsv_window_dump(root, verbose) \
160         __rsv_window_dump((root), (verbose), __FUNCTION__)
161 #else
162 #define rsv_window_dump(root, verbose) do {} while (0)
163 #endif
164
165 static int
166 goal_in_my_reservation(struct ext3_reserve_window *rsv, int goal,
167                         unsigned int group, struct super_block * sb)
168 {
169         unsigned long group_first_block, group_last_block;
170
171         group_first_block = le32_to_cpu(EXT3_SB(sb)->s_es->s_first_data_block) +
172                                 group * EXT3_BLOCKS_PER_GROUP(sb);
173         group_last_block = group_first_block + EXT3_BLOCKS_PER_GROUP(sb) - 1;
174
175         if ((rsv->_rsv_start > group_last_block) ||
176             (rsv->_rsv_end < group_first_block))
177                 return 0;
178         if ((goal >= 0) && ((goal + group_first_block < rsv->_rsv_start)
179                 || (goal + group_first_block > rsv->_rsv_end)))
180                 return 0;
181         return 1;
182 }
183
184 /*
185  * Find the reserved window which includes the goal, or the previous one
186  * if the goal is not in any window.
187  * Returns NULL if there are no windows or if all windows start after the goal.
188  */
189 static struct ext3_reserve_window_node *
190 search_reserve_window(struct rb_root *root, unsigned long goal)
191 {
192         struct rb_node *n = root->rb_node;
193         struct ext3_reserve_window_node *rsv;
194
195         if (!n)
196                 return NULL;
197
198         do {
199                 rsv = rb_entry(n, struct ext3_reserve_window_node, rsv_node);
200
201                 if (goal < rsv->rsv_start)
202                         n = n->rb_left;
203                 else if (goal > rsv->rsv_end)
204                         n = n->rb_right;
205                 else
206                         return rsv;
207         } while (n);
208         /*
209          * We've fallen off the end of the tree: the goal wasn't inside
210          * any particular node.  OK, the previous node must be to one
211          * side of the interval containing the goal.  If it's the RHS,
212          * we need to back up one.
213          */
214         if (rsv->rsv_start > goal) {
215                 n = rb_prev(&rsv->rsv_node);
216                 rsv = rb_entry(n, struct ext3_reserve_window_node, rsv_node);
217         }
218         return rsv;
219 }
220
221 void ext3_rsv_window_add(struct super_block *sb,
222                     struct ext3_reserve_window_node *rsv)
223 {
224         struct rb_root *root = &EXT3_SB(sb)->s_rsv_window_root;
225         struct rb_node *node = &rsv->rsv_node;
226         unsigned int start = rsv->rsv_start;
227
228         struct rb_node ** p = &root->rb_node;
229         struct rb_node * parent = NULL;
230         struct ext3_reserve_window_node *this;
231
232         while (*p)
233         {
234                 parent = *p;
235                 this = rb_entry(parent, struct ext3_reserve_window_node, rsv_node);
236
237                 if (start < this->rsv_start)
238                         p = &(*p)->rb_left;
239                 else if (start > this->rsv_end)
240                         p = &(*p)->rb_right;
241                 else
242                         BUG();
243         }
244
245         rb_link_node(node, parent, p);
246         rb_insert_color(node, root);
247 }
248
249 static void rsv_window_remove(struct super_block *sb,
250                               struct ext3_reserve_window_node *rsv)
251 {
252         rsv->rsv_start = EXT3_RESERVE_WINDOW_NOT_ALLOCATED;
253         rsv->rsv_end = EXT3_RESERVE_WINDOW_NOT_ALLOCATED;
254         rsv->rsv_alloc_hit = 0;
255         rb_erase(&rsv->rsv_node, &EXT3_SB(sb)->s_rsv_window_root);
256 }
257
258 static inline int rsv_is_empty(struct ext3_reserve_window *rsv)
259 {
260         /* a valid reservation end block could not be 0 */
261         return (rsv->_rsv_end == EXT3_RESERVE_WINDOW_NOT_ALLOCATED);
262 }
263 void ext3_init_block_alloc_info(struct inode *inode)
264 {
265         struct ext3_inode_info *ei = EXT3_I(inode);
266         struct ext3_block_alloc_info *block_i = ei->i_block_alloc_info;
267         struct super_block *sb = inode->i_sb;
268
269         block_i = kmalloc(sizeof(*block_i), GFP_NOFS);
270         if (block_i) {
271                 struct ext3_reserve_window_node *rsv = &block_i->rsv_window_node;
272
273                 rsv->rsv_start = EXT3_RESERVE_WINDOW_NOT_ALLOCATED;
274                 rsv->rsv_end = EXT3_RESERVE_WINDOW_NOT_ALLOCATED;
275
276                 /*
277                  * if filesystem is mounted with NORESERVATION, the goal
278                  * reservation window size is set to zero to indicate
279                  * block reservation is off
280                  */
281                 if (!test_opt(sb, RESERVATION))
282                         rsv->rsv_goal_size = 0;
283                 else
284                         rsv->rsv_goal_size = EXT3_DEFAULT_RESERVE_BLOCKS;
285                 rsv->rsv_alloc_hit = 0;
286                 block_i->last_alloc_logical_block = 0;
287                 block_i->last_alloc_physical_block = 0;
288         }
289         ei->i_block_alloc_info = block_i;
290 }
291
292 void ext3_discard_reservation(struct inode *inode)
293 {
294         struct ext3_inode_info *ei = EXT3_I(inode);
295         struct ext3_block_alloc_info *block_i = ei->i_block_alloc_info;
296         struct ext3_reserve_window_node *rsv;
297         spinlock_t *rsv_lock = &EXT3_SB(inode->i_sb)->s_rsv_window_lock;
298
299         if (!block_i)
300                 return;
301
302         rsv = &block_i->rsv_window_node;
303         if (!rsv_is_empty(&rsv->rsv_window)) {
304                 spin_lock(rsv_lock);
305                 if (!rsv_is_empty(&rsv->rsv_window))
306                         rsv_window_remove(inode->i_sb, rsv);
307                 spin_unlock(rsv_lock);
308         }
309 }
310
311 /* Free given blocks, update quota and i_blocks field */
312 void ext3_free_blocks_sb(handle_t *handle, struct super_block *sb,
313                          unsigned long block, unsigned long count,
314                          int *pdquot_freed_blocks)
315 {
316         struct buffer_head *bitmap_bh = NULL;
317         struct buffer_head *gd_bh;
318         unsigned long block_group;
319         unsigned long bit;
320         unsigned long i;
321         unsigned long overflow;
322         struct ext3_group_desc * desc;
323         struct ext3_super_block * es;
324         struct ext3_sb_info *sbi;
325         int err = 0, ret;
326         unsigned group_freed;
327
328         *pdquot_freed_blocks = 0;
329         sbi = EXT3_SB(sb);
330         es = sbi->s_es;
331         if (block < le32_to_cpu(es->s_first_data_block) ||
332             block + count < block ||
333             block + count > le32_to_cpu(es->s_blocks_count)) {
334                 ext3_error (sb, "ext3_free_blocks",
335                             "Freeing blocks not in datazone - "
336                             "block = %lu, count = %lu", block, count);
337                 goto error_return;
338         }
339
340         ext3_debug ("freeing block(s) %lu-%lu\n", block, block + count - 1);
341
342 do_more:
343         overflow = 0;
344         block_group = (block - le32_to_cpu(es->s_first_data_block)) /
345                       EXT3_BLOCKS_PER_GROUP(sb);
346         bit = (block - le32_to_cpu(es->s_first_data_block)) %
347                       EXT3_BLOCKS_PER_GROUP(sb);
348         /*
349          * Check to see if we are freeing blocks across a group
350          * boundary.
351          */
352         if (bit + count > EXT3_BLOCKS_PER_GROUP(sb)) {
353                 overflow = bit + count - EXT3_BLOCKS_PER_GROUP(sb);
354                 count -= overflow;
355         }
356         brelse(bitmap_bh);
357         bitmap_bh = read_block_bitmap(sb, block_group);
358         if (!bitmap_bh)
359                 goto error_return;
360         desc = ext3_get_group_desc (sb, block_group, &gd_bh);
361         if (!desc)
362                 goto error_return;
363
364         if (in_range (le32_to_cpu(desc->bg_block_bitmap), block, count) ||
365             in_range (le32_to_cpu(desc->bg_inode_bitmap), block, count) ||
366             in_range (block, le32_to_cpu(desc->bg_inode_table),
367                       sbi->s_itb_per_group) ||
368             in_range (block + count - 1, le32_to_cpu(desc->bg_inode_table),
369                       sbi->s_itb_per_group))
370                 ext3_error (sb, "ext3_free_blocks",
371                             "Freeing blocks in system zones - "
372                             "Block = %lu, count = %lu",
373                             block, count);
374
375         /*
376          * We are about to start releasing blocks in the bitmap,
377          * so we need undo access.
378          */
379         /* @@@ check errors */
380         BUFFER_TRACE(bitmap_bh, "getting undo access");
381         err = ext3_journal_get_undo_access(handle, bitmap_bh);
382         if (err)
383                 goto error_return;
384
385         /*
386          * We are about to modify some metadata.  Call the journal APIs
387          * to unshare ->b_data if a currently-committing transaction is
388          * using it
389          */
390         BUFFER_TRACE(gd_bh, "get_write_access");
391         err = ext3_journal_get_write_access(handle, gd_bh);
392         if (err)
393                 goto error_return;
394
395         jbd_lock_bh_state(bitmap_bh);
396
397         for (i = 0, group_freed = 0; i < count; i++) {
398                 /*
399                  * An HJ special.  This is expensive...
400                  */
401 #ifdef CONFIG_JBD_DEBUG
402                 jbd_unlock_bh_state(bitmap_bh);
403                 {
404                         struct buffer_head *debug_bh;
405                         debug_bh = sb_find_get_block(sb, block + i);
406                         if (debug_bh) {
407                                 BUFFER_TRACE(debug_bh, "Deleted!");
408                                 if (!bh2jh(bitmap_bh)->b_committed_data)
409                                         BUFFER_TRACE(debug_bh,
410                                                 "No commited data in bitmap");
411                                 BUFFER_TRACE2(debug_bh, bitmap_bh, "bitmap");
412                                 __brelse(debug_bh);
413                         }
414                 }
415                 jbd_lock_bh_state(bitmap_bh);
416 #endif
417                 if (need_resched()) {
418                         jbd_unlock_bh_state(bitmap_bh);
419                         cond_resched();
420                         jbd_lock_bh_state(bitmap_bh);
421                 }
422                 /* @@@ This prevents newly-allocated data from being
423                  * freed and then reallocated within the same
424                  * transaction. 
425                  * 
426                  * Ideally we would want to allow that to happen, but to
427                  * do so requires making journal_forget() capable of
428                  * revoking the queued write of a data block, which
429                  * implies blocking on the journal lock.  *forget()
430                  * cannot block due to truncate races.
431                  *
432                  * Eventually we can fix this by making journal_forget()
433                  * return a status indicating whether or not it was able
434                  * to revoke the buffer.  On successful revoke, it is
435                  * safe not to set the allocation bit in the committed
436                  * bitmap, because we know that there is no outstanding
437                  * activity on the buffer any more and so it is safe to
438                  * reallocate it.  
439                  */
440                 BUFFER_TRACE(bitmap_bh, "set in b_committed_data");
441                 J_ASSERT_BH(bitmap_bh,
442                                 bh2jh(bitmap_bh)->b_committed_data != NULL);
443                 ext3_set_bit_atomic(sb_bgl_lock(sbi, block_group), bit + i,
444                                 bh2jh(bitmap_bh)->b_committed_data);
445
446                 /*
447                  * We clear the bit in the bitmap after setting the committed
448                  * data bit, because this is the reverse order to that which
449                  * the allocator uses.
450                  */
451                 BUFFER_TRACE(bitmap_bh, "clear bit");
452                 if (!ext3_clear_bit_atomic(sb_bgl_lock(sbi, block_group),
453                                                 bit + i, bitmap_bh->b_data)) {
454                         jbd_unlock_bh_state(bitmap_bh);
455                         ext3_error(sb, __FUNCTION__,
456                                 "bit already cleared for block %lu", block + i);
457                         jbd_lock_bh_state(bitmap_bh);
458                         BUFFER_TRACE(bitmap_bh, "bit already cleared");
459                 } else {
460                         group_freed++;
461                 }
462         }
463         jbd_unlock_bh_state(bitmap_bh);
464
465         spin_lock(sb_bgl_lock(sbi, block_group));
466         desc->bg_free_blocks_count =
467                 cpu_to_le16(le16_to_cpu(desc->bg_free_blocks_count) +
468                         group_freed);
469         spin_unlock(sb_bgl_lock(sbi, block_group));
470         percpu_counter_mod(&sbi->s_freeblocks_counter, count);
471
472         /* We dirtied the bitmap block */
473         BUFFER_TRACE(bitmap_bh, "dirtied bitmap block");
474         err = ext3_journal_dirty_metadata(handle, bitmap_bh);
475
476         /* And the group descriptor block */
477         BUFFER_TRACE(gd_bh, "dirtied group descriptor block");
478         ret = ext3_journal_dirty_metadata(handle, gd_bh);
479         if (!err) err = ret;
480         *pdquot_freed_blocks += group_freed;
481
482         if (overflow && !err) {
483                 block += count;
484                 count = overflow;
485                 goto do_more;
486         }
487         sb->s_dirt = 1;
488 error_return:
489         brelse(bitmap_bh);
490         ext3_std_error(sb, err);
491         return;
492 }
493
494 /* Free given blocks, update quota and i_blocks field */
495 void ext3_free_blocks(handle_t *handle, struct inode *inode,
496                         unsigned long block, unsigned long count)
497 {
498         struct super_block * sb;
499         int dquot_freed_blocks;
500
501         sb = inode->i_sb;
502         if (!sb) {
503                 printk ("ext3_free_blocks: nonexistent device");
504                 return;
505         }
506         ext3_free_blocks_sb(handle, sb, block, count, &dquot_freed_blocks);
507         if (dquot_freed_blocks)
508                 DQUOT_FREE_BLOCK(inode, dquot_freed_blocks);
509         return;
510 }
511
512 /*
513  * For ext3 allocations, we must not reuse any blocks which are
514  * allocated in the bitmap buffer's "last committed data" copy.  This
515  * prevents deletes from freeing up the page for reuse until we have
516  * committed the delete transaction.
517  *
518  * If we didn't do this, then deleting something and reallocating it as
519  * data would allow the old block to be overwritten before the
520  * transaction committed (because we force data to disk before commit).
521  * This would lead to corruption if we crashed between overwriting the
522  * data and committing the delete. 
523  *
524  * @@@ We may want to make this allocation behaviour conditional on
525  * data-writes at some point, and disable it for metadata allocations or
526  * sync-data inodes.
527  */
528 static int ext3_test_allocatable(int nr, struct buffer_head *bh)
529 {
530         int ret;
531         struct journal_head *jh = bh2jh(bh);
532
533         if (ext3_test_bit(nr, bh->b_data))
534                 return 0;
535
536         jbd_lock_bh_state(bh);
537         if (!jh->b_committed_data)
538                 ret = 1;
539         else
540                 ret = !ext3_test_bit(nr, jh->b_committed_data);
541         jbd_unlock_bh_state(bh);
542         return ret;
543 }
544
545 static int
546 bitmap_search_next_usable_block(int start, struct buffer_head *bh,
547                                         int maxblocks)
548 {
549         int next;
550         struct journal_head *jh = bh2jh(bh);
551
552         /*
553          * The bitmap search --- search forward alternately through the actual
554          * bitmap and the last-committed copy until we find a bit free in
555          * both
556          */
557         while (start < maxblocks) {
558                 next = ext3_find_next_zero_bit(bh->b_data, maxblocks, start);
559                 if (next >= maxblocks)
560                         return -1;
561                 if (ext3_test_allocatable(next, bh))
562                         return next;
563                 jbd_lock_bh_state(bh);
564                 if (jh->b_committed_data)
565                         start = ext3_find_next_zero_bit(jh->b_committed_data,
566                                                         maxblocks, next);
567                 jbd_unlock_bh_state(bh);
568         }
569         return -1;
570 }
571
572 /*
573  * Find an allocatable block in a bitmap.  We honour both the bitmap and
574  * its last-committed copy (if that exists), and perform the "most
575  * appropriate allocation" algorithm of looking for a free block near
576  * the initial goal; then for a free byte somewhere in the bitmap; then
577  * for any free bit in the bitmap.
578  */
579 static int
580 find_next_usable_block(int start, struct buffer_head *bh, int maxblocks)
581 {
582         int 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                 int 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, int 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 int
655 ext3_try_to_allocate(struct super_block *sb, handle_t *handle, int group,
656         struct buffer_head *bitmap_bh, int goal, struct ext3_reserve_window *my_rsv)
657 {
658         int group_first_block, start, end;
659
660         /* we do allocation within the reservation window if we have a window */
661         if (my_rsv) {
662                 group_first_block =
663                         le32_to_cpu(EXT3_SB(sb)->s_es->s_first_data_block) +
664                         group * EXT3_BLOCKS_PER_GROUP(sb);
665                 if (my_rsv->_rsv_start >= group_first_block)
666                         start = my_rsv->_rsv_start - group_first_block;
667                 else
668                         /* reservation window cross group boundary */
669                         start = 0;
670                 end = my_rsv->_rsv_end - group_first_block + 1;
671                 if (end > EXT3_BLOCKS_PER_GROUP(sb))
672                         /* reservation window crosses group boundary */
673                         end = EXT3_BLOCKS_PER_GROUP(sb);
674                 if ((start <= goal) && (goal < end))
675                         start = goal;
676                 else
677                         goal = -1;
678         } else {
679                 if (goal > 0)
680                         start = goal;
681                 else
682                         start = 0;
683                 end = EXT3_BLOCKS_PER_GROUP(sb);
684         }
685
686         BUG_ON(start > EXT3_BLOCKS_PER_GROUP(sb));
687
688 repeat:
689         if (goal < 0 || !ext3_test_allocatable(goal, bitmap_bh)) {
690                 goal = find_next_usable_block(start, bitmap_bh, end);
691                 if (goal < 0)
692                         goto fail_access;
693                 if (!my_rsv) {
694                         int i;
695
696                         for (i = 0; i < 7 && goal > start &&
697                                         ext3_test_allocatable(goal - 1,
698                                                                 bitmap_bh);
699                                         i++, goal--)
700                                 ;
701                 }
702         }
703         start = goal;
704
705         if (!claim_block(sb_bgl_lock(EXT3_SB(sb), group), goal, bitmap_bh)) {
706                 /*
707                  * The block was allocated by another thread, or it was
708                  * allocated and then freed by another thread
709                  */
710                 start++;
711                 goal++;
712                 if (start >= end)
713                         goto fail_access;
714                 goto repeat;
715         }
716         return goal;
717 fail_access:
718         return -1;
719 }
720
721 /**
722  *      find_next_reservable_window():
723  *              find a reservable space within the given range.
724  *              It does not allocate the reservation window for now:
725  *              alloc_new_reservation() will do the work later.
726  *
727  *      @search_head: the head of the searching list;
728  *              This is not necessarily the list head of the whole filesystem
729  *
730  *              We have both head and start_block to assist the search
731  *              for the reservable space. The list starts from head,
732  *              but we will shift to the place where start_block is,
733  *              then start from there, when looking for a reservable space.
734  *
735  *      @size: the target new reservation window size
736  *
737  *      @group_first_block: the first block we consider to start
738  *                      the real search from
739  *
740  *      @last_block:
741  *              the maximum block number that our goal reservable space
742  *              could start from. This is normally the last block in this
743  *              group. The search will end when we found the start of next
744  *              possible reservable space is out of this boundary.
745  *              This could handle the cross boundary reservation window
746  *              request.
747  *
748  *      basically we search from the given range, rather than the whole
749  *      reservation double linked list, (start_block, last_block)
750  *      to find a free region that is of my size and has not
751  *      been reserved.
752  *
753  */
754 static int find_next_reservable_window(
755                                 struct ext3_reserve_window_node *search_head,
756                                 struct ext3_reserve_window_node *my_rsv,
757                                 struct super_block * sb, int start_block,
758                                 int last_block)
759 {
760         struct rb_node *next;
761         struct ext3_reserve_window_node *rsv, *prev;
762         int cur;
763         int size = my_rsv->rsv_goal_size;
764
765         /* TODO: make the start of the reservation window byte-aligned */
766         /* cur = *start_block & ~7;*/
767         cur = start_block;
768         rsv = search_head;
769         if (!rsv)
770                 return -1;
771
772         while (1) {
773                 if (cur <= rsv->rsv_end)
774                         cur = rsv->rsv_end + 1;
775
776                 /* TODO?
777                  * in the case we could not find a reservable space
778                  * that is what is expected, during the re-search, we could
779                  * remember what's the largest reservable space we could have
780                  * and return that one.
781                  *
782                  * For now it will fail if we could not find the reservable
783                  * space with expected-size (or more)...
784                  */
785                 if (cur > last_block)
786                         return -1;              /* fail */
787
788                 prev = rsv;
789                 next = rb_next(&rsv->rsv_node);
790                 rsv = list_entry(next,struct ext3_reserve_window_node,rsv_node);
791
792                 /*
793                  * Reached the last reservation, we can just append to the
794                  * previous one.
795                  */
796                 if (!next)
797                         break;
798
799                 if (cur + size <= rsv->rsv_start) {
800                         /*
801                          * Found a reserveable space big enough.  We could
802                          * have a reservation across the group boundary here
803                          */
804                         break;
805                 }
806         }
807         /*
808          * we come here either :
809          * when we reach the end of the whole list,
810          * and there is empty reservable space after last entry in the list.
811          * append it to the end of the list.
812          *
813          * or we found one reservable space in the middle of the list,
814          * return the reservation window that we could append to.
815          * succeed.
816          */
817
818         if ((prev != my_rsv) && (!rsv_is_empty(&my_rsv->rsv_window)))
819                 rsv_window_remove(sb, my_rsv);
820
821         /*
822          * Let's book the whole avaliable window for now.  We will check the
823          * disk bitmap later and then, if there are free blocks then we adjust
824          * the window size if it's larger than requested.
825          * Otherwise, we will remove this node from the tree next time
826          * call find_next_reservable_window.
827          */
828         my_rsv->rsv_start = cur;
829         my_rsv->rsv_end = cur + size - 1;
830         my_rsv->rsv_alloc_hit = 0;
831
832         if (prev != my_rsv)
833                 ext3_rsv_window_add(sb, my_rsv);
834
835         return 0;
836 }
837
838 /**
839  *      alloc_new_reservation()--allocate a new reservation window
840  *
841  *              To make a new reservation, we search part of the filesystem
842  *              reservation list (the list that inside the group). We try to
843  *              allocate a new reservation window near the allocation goal,
844  *              or the beginning of the group, if there is no goal.
845  *
846  *              We first find a reservable space after the goal, then from
847  *              there, we check the bitmap for the first free block after
848  *              it. If there is no free block until the end of group, then the
849  *              whole group is full, we failed. Otherwise, check if the free
850  *              block is inside the expected reservable space, if so, we
851  *              succeed.
852  *              If the first free block is outside the reservable space, then
853  *              start from the first free block, we search for next available
854  *              space, and go on.
855  *
856  *      on succeed, a new reservation will be found and inserted into the list
857  *      It contains at least one free block, and it does not overlap with other
858  *      reservation windows.
859  *
860  *      failed: we failed to find a reservation window in this group
861  *
862  *      @rsv: the reservation
863  *
864  *      @goal: The goal (group-relative).  It is where the search for a
865  *              free reservable space should start from.
866  *              if we have a goal(goal >0 ), then start from there,
867  *              no goal(goal = -1), we start from the first block
868  *              of the group.
869  *
870  *      @sb: the super block
871  *      @group: the group we are trying to allocate in
872  *      @bitmap_bh: the block group block bitmap
873  *
874  */
875 static int alloc_new_reservation(struct ext3_reserve_window_node *my_rsv,
876                 int goal, struct super_block *sb,
877                 unsigned int group, struct buffer_head *bitmap_bh)
878 {
879         struct ext3_reserve_window_node *search_head;
880         int group_first_block, group_end_block, start_block;
881         int first_free_block;
882         struct rb_root *fs_rsv_root = &EXT3_SB(sb)->s_rsv_window_root;
883         unsigned long size;
884         int ret;
885         spinlock_t *rsv_lock = &EXT3_SB(sb)->s_rsv_window_lock;
886
887         group_first_block = le32_to_cpu(EXT3_SB(sb)->s_es->s_first_data_block) +
888                                 group * EXT3_BLOCKS_PER_GROUP(sb);
889         group_end_block = group_first_block + EXT3_BLOCKS_PER_GROUP(sb) - 1;
890
891         if (goal < 0)
892                 start_block = group_first_block;
893         else
894                 start_block = goal + group_first_block;
895
896         size = my_rsv->rsv_goal_size;
897
898         if (!rsv_is_empty(&my_rsv->rsv_window)) {
899                 /*
900                  * if the old reservation is cross group boundary
901                  * and if the goal is inside the old reservation window,
902                  * we will come here when we just failed to allocate from
903                  * the first part of the window. We still have another part
904                  * that belongs to the next group. In this case, there is no
905                  * point to discard our window and try to allocate a new one
906                  * in this group(which will fail). we should
907                  * keep the reservation window, just simply move on.
908                  *
909                  * Maybe we could shift the start block of the reservation
910                  * window to the first block of next group.
911                  */
912
913                 if ((my_rsv->rsv_start <= group_end_block) &&
914                                 (my_rsv->rsv_end > group_end_block) &&
915                                 (start_block >= my_rsv->rsv_start))
916                         return -1;
917
918                 if ((my_rsv->rsv_alloc_hit >
919                      (my_rsv->rsv_end - my_rsv->rsv_start + 1) / 2)) {
920                         /*
921                          * if we previously allocation hit ration is greater than half
922                          * we double the size of reservation window next time
923                          * otherwise keep the same
924                          */
925                         size = size * 2;
926                         if (size > EXT3_MAX_RESERVE_BLOCKS)
927                                 size = EXT3_MAX_RESERVE_BLOCKS;
928                         my_rsv->rsv_goal_size= size;
929                 }
930         }
931
932         spin_lock(rsv_lock);
933         /*
934          * shift the search start to the window near the goal block
935          */
936         search_head = search_reserve_window(fs_rsv_root, start_block);
937
938         /*
939          * find_next_reservable_window() simply finds a reservable window
940          * inside the given range(start_block, group_end_block).
941          *
942          * To make sure the reservation window has a free bit inside it, we
943          * need to check the bitmap after we found a reservable window.
944          */
945 retry:
946         ret = find_next_reservable_window(search_head, my_rsv, sb,
947                                                 start_block, group_end_block);
948
949         if (ret == -1) {
950                 if (!rsv_is_empty(&my_rsv->rsv_window))
951                         rsv_window_remove(sb, my_rsv);
952                 spin_unlock(rsv_lock);
953                 return -1;
954         }
955
956         /*
957          * On success, find_next_reservable_window() returns the
958          * reservation window where there is a reservable space after it.
959          * Before we reserve this reservable space, we need
960          * to make sure there is at least a free block inside this region.
961          *
962          * searching the first free bit on the block bitmap and copy of
963          * last committed bitmap alternatively, until we found a allocatable
964          * block. Search start from the start block of the reservable space
965          * we just found.
966          */
967         spin_unlock(rsv_lock);
968         first_free_block = bitmap_search_next_usable_block(
969                         my_rsv->rsv_start - group_first_block,
970                         bitmap_bh, group_end_block - group_first_block + 1);
971
972         if (first_free_block < 0) {
973                 /*
974                  * no free block left on the bitmap, no point
975                  * to reserve the space. return failed.
976                  */
977                 spin_lock(rsv_lock);
978                 if (!rsv_is_empty(&my_rsv->rsv_window))
979                         rsv_window_remove(sb, my_rsv);
980                 spin_unlock(rsv_lock);
981                 return -1;              /* failed */
982         }
983
984         start_block = first_free_block + group_first_block;
985         /*
986          * check if the first free block is within the
987          * free space we just reserved
988          */
989         if (start_block >= my_rsv->rsv_start && start_block < my_rsv->rsv_end)
990                 return 0;               /* success */
991         /*
992          * if the first free bit we found is out of the reservable space
993          * continue search for next reservable space,
994          * start from where the free block is,
995          * we also shift the list head to where we stopped last time
996          */
997         search_head = my_rsv;
998         spin_lock(rsv_lock);
999         goto retry;
1000 }
1001
1002 /*
1003  * This is the main function used to allocate a new block and its reservation
1004  * window.
1005  *
1006  * Each time when a new block allocation is need, first try to allocate from
1007  * its own reservation.  If it does not have a reservation window, instead of
1008  * looking for a free bit on bitmap first, then look up the reservation list to
1009  * see if it is inside somebody else's reservation window, we try to allocate a
1010  * reservation window for it starting from the goal first. Then do the block
1011  * allocation within the reservation window.
1012  *
1013  * This will avoid keeping on searching the reservation list again and
1014  * again when somebody is looking for a free block (without
1015  * reservation), and there are lots of free blocks, but they are all
1016  * being reserved.
1017  *
1018  * We use a sorted double linked list for the per-filesystem reservation list.
1019  * The insert, remove and find a free space(non-reserved) operations for the
1020  * sorted double linked list should be fast.
1021  *
1022  */
1023 static int
1024 ext3_try_to_allocate_with_rsv(struct super_block *sb, handle_t *handle,
1025                         unsigned int group, struct buffer_head *bitmap_bh,
1026                         int goal, struct ext3_reserve_window_node * my_rsv,
1027                         int *errp)
1028 {
1029         unsigned long group_first_block;
1030         int ret = 0;
1031         int fatal;
1032
1033         *errp = 0;
1034
1035         /*
1036          * Make sure we use undo access for the bitmap, because it is critical
1037          * that we do the frozen_data COW on bitmap buffers in all cases even
1038          * if the buffer is in BJ_Forget state in the committing transaction.
1039          */
1040         BUFFER_TRACE(bitmap_bh, "get undo access for new block");
1041         fatal = ext3_journal_get_undo_access(handle, bitmap_bh);
1042         if (fatal) {
1043                 *errp = fatal;
1044                 return -1;
1045         }
1046
1047         /*
1048          * we don't deal with reservation when
1049          * filesystem is mounted without reservation
1050          * or the file is not a regular file
1051          * or last attempt to allocate a block with reservation turned on failed
1052          */
1053         if (my_rsv == NULL ) {
1054                 ret = ext3_try_to_allocate(sb, handle, group, bitmap_bh, goal, NULL);
1055                 goto out;
1056         }
1057         /*
1058          * goal is a group relative block number (if there is a goal)
1059          * 0 < goal < EXT3_BLOCKS_PER_GROUP(sb)
1060          * first block is a filesystem wide block number
1061          * first block is the block number of the first block in this group
1062          */
1063         group_first_block = le32_to_cpu(EXT3_SB(sb)->s_es->s_first_data_block) +
1064                         group * EXT3_BLOCKS_PER_GROUP(sb);
1065
1066         /*
1067          * Basically we will allocate a new block from inode's reservation
1068          * window.
1069          *
1070          * We need to allocate a new reservation window, if:
1071          * a) inode does not have a reservation window; or
1072          * b) last attempt to allocate a block from existing reservation
1073          *    failed; or
1074          * c) we come here with a goal and with a reservation window
1075          *
1076          * We do not need to allocate a new reservation window if we come here
1077          * at the beginning with a goal and the goal is inside the window, or
1078          * we don't have a goal but already have a reservation window.
1079          * then we could go to allocate from the reservation window directly.
1080          */
1081         while (1) {
1082                 if (rsv_is_empty(&my_rsv->rsv_window) || (ret < 0) ||
1083                         !goal_in_my_reservation(&my_rsv->rsv_window, goal, group, sb)) {
1084                         ret = alloc_new_reservation(my_rsv, goal, sb,
1085                                                         group, bitmap_bh);
1086                         if (ret < 0)
1087                                 break;                  /* failed */
1088
1089                         if (!goal_in_my_reservation(&my_rsv->rsv_window, goal, group, sb))
1090                                 goal = -1;
1091                 }
1092                 if ((my_rsv->rsv_start >= group_first_block + EXT3_BLOCKS_PER_GROUP(sb))
1093                     || (my_rsv->rsv_end < group_first_block))
1094                         BUG();
1095                 ret = ext3_try_to_allocate(sb, handle, group, bitmap_bh, goal,
1096                                            &my_rsv->rsv_window);
1097                 if (ret >= 0) {
1098                         my_rsv->rsv_alloc_hit++;
1099                         break;                          /* succeed */
1100                 }
1101         }
1102 out:
1103         if (ret >= 0) {
1104                 BUFFER_TRACE(bitmap_bh, "journal_dirty_metadata for "
1105                                         "bitmap block");
1106                 fatal = ext3_journal_dirty_metadata(handle, bitmap_bh);
1107                 if (fatal) {
1108                         *errp = fatal;
1109                         return -1;
1110                 }
1111                 return ret;
1112         }
1113
1114         BUFFER_TRACE(bitmap_bh, "journal_release_buffer");
1115         ext3_journal_release_buffer(handle, bitmap_bh);
1116         return ret;
1117 }
1118
1119 static int ext3_has_free_blocks(struct ext3_sb_info *sbi)
1120 {
1121         int free_blocks, root_blocks;
1122
1123         free_blocks = percpu_counter_read_positive(&sbi->s_freeblocks_counter);
1124         root_blocks = le32_to_cpu(sbi->s_es->s_r_blocks_count);
1125         if (free_blocks < root_blocks + 1 && !capable(CAP_SYS_RESOURCE) &&
1126                 sbi->s_resuid != current->fsuid &&
1127                 (sbi->s_resgid == 0 || !in_group_p (sbi->s_resgid))) {
1128                 return 0;
1129         }
1130         return 1;
1131 }
1132
1133 /*
1134  * ext3_should_retry_alloc() is called when ENOSPC is returned, and if
1135  * it is profitable to retry the operation, this function will wait
1136  * for the current or commiting transaction to complete, and then
1137  * return TRUE.
1138  */
1139 int ext3_should_retry_alloc(struct super_block *sb, int *retries)
1140 {
1141         if (!ext3_has_free_blocks(EXT3_SB(sb)) || (*retries)++ > 3)
1142                 return 0;
1143
1144         jbd_debug(1, "%s: retrying operation after ENOSPC\n", sb->s_id);
1145
1146         return journal_force_commit_nested(EXT3_SB(sb)->s_journal);
1147 }
1148
1149 /*
1150  * ext3_new_block uses a goal block to assist allocation.  If the goal is
1151  * free, or there is a free block within 32 blocks of the goal, that block
1152  * is allocated.  Otherwise a forward search is made for a free block; within 
1153  * each block group the search first looks for an entire free byte in the block
1154  * bitmap, and then for any free bit if that fails.
1155  * This function also updates quota and i_blocks field.
1156  */
1157 int ext3_new_block(handle_t *handle, struct inode *inode,
1158                         unsigned long goal, int *errp)
1159 {
1160         struct buffer_head *bitmap_bh = NULL;
1161         struct buffer_head *gdp_bh;
1162         int group_no;
1163         int goal_group;
1164         int ret_block;
1165         int bgi;                        /* blockgroup iteration index */
1166         int target_block;
1167         int fatal = 0, err;
1168         int performed_allocation = 0;
1169         int free_blocks;
1170         struct super_block *sb;
1171         struct ext3_group_desc *gdp;
1172         struct ext3_super_block *es;
1173         struct ext3_sb_info *sbi;
1174         struct ext3_reserve_window_node *my_rsv = NULL;
1175         struct ext3_block_alloc_info *block_i;
1176         unsigned short windowsz = 0;
1177 #ifdef EXT3FS_DEBUG
1178         static int goal_hits, goal_attempts;
1179 #endif
1180         unsigned long ngroups;
1181
1182         *errp = -ENOSPC;
1183         sb = inode->i_sb;
1184         if (!sb) {
1185                 printk("ext3_new_block: nonexistent device");
1186                 return 0;
1187         }
1188
1189         /*
1190          * Check quota for allocation of this block.
1191          */
1192         if (DQUOT_ALLOC_BLOCK(inode, 1)) {
1193                 *errp = -EDQUOT;
1194                 return 0;
1195         }
1196
1197         sbi = EXT3_SB(sb);
1198         es = EXT3_SB(sb)->s_es;
1199         ext3_debug("goal=%lu.\n", goal);
1200         /*
1201          * Allocate a block from reservation only when
1202          * filesystem is mounted with reservation(default,-o reservation), and
1203          * it's a regular file, and
1204          * the desired window size is greater than 0 (One could use ioctl
1205          * command EXT3_IOC_SETRSVSZ to set the window size to 0 to turn off
1206          * reservation on that particular file)
1207          */
1208         block_i = EXT3_I(inode)->i_block_alloc_info;
1209         if (block_i && ((windowsz = block_i->rsv_window_node.rsv_goal_size) > 0))
1210                 my_rsv = &block_i->rsv_window_node;
1211
1212         if (!ext3_has_free_blocks(sbi)) {
1213                 *errp = -ENOSPC;
1214                 goto out;
1215         }
1216
1217         /*
1218          * First, test whether the goal block is free.
1219          */
1220         if (goal < le32_to_cpu(es->s_first_data_block) ||
1221             goal >= le32_to_cpu(es->s_blocks_count))
1222                 goal = le32_to_cpu(es->s_first_data_block);
1223         group_no = (goal - le32_to_cpu(es->s_first_data_block)) /
1224                         EXT3_BLOCKS_PER_GROUP(sb);
1225         gdp = ext3_get_group_desc(sb, group_no, &gdp_bh);
1226         if (!gdp)
1227                 goto io_error;
1228
1229         goal_group = group_no;
1230 retry:
1231         free_blocks = le16_to_cpu(gdp->bg_free_blocks_count);
1232         /*
1233          * if there is not enough free blocks to make a new resevation
1234          * turn off reservation for this allocation
1235          */
1236         if (my_rsv && (free_blocks < windowsz)
1237                 && (rsv_is_empty(&my_rsv->rsv_window)))
1238                 my_rsv = NULL;
1239
1240         if (free_blocks > 0) {
1241                 ret_block = ((goal - le32_to_cpu(es->s_first_data_block)) %
1242                                 EXT3_BLOCKS_PER_GROUP(sb));
1243                 bitmap_bh = read_block_bitmap(sb, group_no);
1244                 if (!bitmap_bh)
1245                         goto io_error;
1246                 ret_block = ext3_try_to_allocate_with_rsv(sb, handle, group_no,
1247                                         bitmap_bh, ret_block, my_rsv, &fatal);
1248                 if (fatal)
1249                         goto out;
1250                 if (ret_block >= 0)
1251                         goto allocated;
1252         }
1253
1254         ngroups = EXT3_SB(sb)->s_groups_count;
1255         smp_rmb();
1256
1257         /*
1258          * Now search the rest of the groups.  We assume that 
1259          * i and gdp correctly point to the last group visited.
1260          */
1261         for (bgi = 0; bgi < ngroups; bgi++) {
1262                 group_no++;
1263                 if (group_no >= ngroups)
1264                         group_no = 0;
1265                 gdp = ext3_get_group_desc(sb, group_no, &gdp_bh);
1266                 if (!gdp) {
1267                         *errp = -EIO;
1268                         goto out;
1269                 }
1270                 free_blocks = le16_to_cpu(gdp->bg_free_blocks_count);
1271                 /*
1272                  * skip this group if the number of
1273                  * free blocks is less than half of the reservation
1274                  * window size.
1275                  */
1276                 if (free_blocks <= (windowsz/2))
1277                         continue;
1278
1279                 brelse(bitmap_bh);
1280                 bitmap_bh = read_block_bitmap(sb, group_no);
1281                 if (!bitmap_bh)
1282                         goto io_error;
1283                 ret_block = ext3_try_to_allocate_with_rsv(sb, handle, group_no,
1284                                         bitmap_bh, -1, my_rsv, &fatal);
1285                 if (fatal)
1286                         goto out;
1287                 if (ret_block >= 0) 
1288                         goto allocated;
1289         }
1290         /*
1291          * We may end up a bogus ealier ENOSPC error due to
1292          * filesystem is "full" of reservations, but
1293          * there maybe indeed free blocks avaliable on disk
1294          * In this case, we just forget about the reservations
1295          * just do block allocation as without reservations.
1296          */
1297         if (my_rsv) {
1298                 my_rsv = NULL;
1299                 group_no = goal_group;
1300                 goto retry;
1301         }
1302         /* No space left on the device */
1303         *errp = -ENOSPC;
1304         goto out;
1305
1306 allocated:
1307
1308         ext3_debug("using block group %d(%d)\n",
1309                         group_no, gdp->bg_free_blocks_count);
1310
1311         BUFFER_TRACE(gdp_bh, "get_write_access");
1312         fatal = ext3_journal_get_write_access(handle, gdp_bh);
1313         if (fatal)
1314                 goto out;
1315
1316         target_block = ret_block + group_no * EXT3_BLOCKS_PER_GROUP(sb)
1317                                 + le32_to_cpu(es->s_first_data_block);
1318
1319         if (target_block == le32_to_cpu(gdp->bg_block_bitmap) ||
1320             target_block == le32_to_cpu(gdp->bg_inode_bitmap) ||
1321             in_range(target_block, le32_to_cpu(gdp->bg_inode_table),
1322                       EXT3_SB(sb)->s_itb_per_group))
1323                 ext3_error(sb, "ext3_new_block",
1324                             "Allocating block in system zone - "
1325                             "block = %u", target_block);
1326
1327         performed_allocation = 1;
1328
1329 #ifdef CONFIG_JBD_DEBUG
1330         {
1331                 struct buffer_head *debug_bh;
1332
1333                 /* Record bitmap buffer state in the newly allocated block */
1334                 debug_bh = sb_find_get_block(sb, target_block);
1335                 if (debug_bh) {
1336                         BUFFER_TRACE(debug_bh, "state when allocated");
1337                         BUFFER_TRACE2(debug_bh, bitmap_bh, "bitmap state");
1338                         brelse(debug_bh);
1339                 }
1340         }
1341         jbd_lock_bh_state(bitmap_bh);
1342         spin_lock(sb_bgl_lock(sbi, group_no));
1343         if (buffer_jbd(bitmap_bh) && bh2jh(bitmap_bh)->b_committed_data) {
1344                 if (ext3_test_bit(ret_block,
1345                                 bh2jh(bitmap_bh)->b_committed_data)) {
1346                         printk("%s: block was unexpectedly set in "
1347                                 "b_committed_data\n", __FUNCTION__);
1348                 }
1349         }
1350         ext3_debug("found bit %d\n", ret_block);
1351         spin_unlock(sb_bgl_lock(sbi, group_no));
1352         jbd_unlock_bh_state(bitmap_bh);
1353 #endif
1354
1355         /* ret_block was blockgroup-relative.  Now it becomes fs-relative */
1356         ret_block = target_block;
1357
1358         if (ret_block >= le32_to_cpu(es->s_blocks_count)) {
1359                 ext3_error(sb, "ext3_new_block",
1360                             "block(%d) >= blocks count(%d) - "
1361                             "block_group = %d, es == %p ", ret_block,
1362                         le32_to_cpu(es->s_blocks_count), group_no, es);
1363                 goto out;
1364         }
1365
1366         /*
1367          * It is up to the caller to add the new buffer to a journal
1368          * list of some description.  We don't know in advance whether
1369          * the caller wants to use it as metadata or data.
1370          */
1371         ext3_debug("allocating block %d. Goal hits %d of %d.\n",
1372                         ret_block, goal_hits, goal_attempts);
1373
1374         spin_lock(sb_bgl_lock(sbi, group_no));
1375         gdp->bg_free_blocks_count =
1376                         cpu_to_le16(le16_to_cpu(gdp->bg_free_blocks_count) - 1);
1377         spin_unlock(sb_bgl_lock(sbi, group_no));
1378         percpu_counter_mod(&sbi->s_freeblocks_counter, -1);
1379
1380         BUFFER_TRACE(gdp_bh, "journal_dirty_metadata for group descriptor");
1381         err = ext3_journal_dirty_metadata(handle, gdp_bh);
1382         if (!fatal)
1383                 fatal = err;
1384
1385         sb->s_dirt = 1;
1386         if (fatal)
1387                 goto out;
1388
1389         *errp = 0;
1390         brelse(bitmap_bh);
1391         return ret_block;
1392
1393 io_error:
1394         *errp = -EIO;
1395 out:
1396         if (fatal) {
1397                 *errp = fatal;
1398                 ext3_std_error(sb, fatal);
1399         }
1400         /*
1401          * Undo the block allocation
1402          */
1403         if (!performed_allocation)
1404                 DQUOT_FREE_BLOCK(inode, 1);
1405         brelse(bitmap_bh);
1406         return 0;
1407 }
1408
1409 unsigned long ext3_count_free_blocks(struct super_block *sb)
1410 {
1411         unsigned long desc_count;
1412         struct ext3_group_desc *gdp;
1413         int i;
1414         unsigned long ngroups = EXT3_SB(sb)->s_groups_count;
1415 #ifdef EXT3FS_DEBUG
1416         struct ext3_super_block *es;
1417         unsigned long bitmap_count, x;
1418         struct buffer_head *bitmap_bh = NULL;
1419
1420         es = EXT3_SB(sb)->s_es;
1421         desc_count = 0;
1422         bitmap_count = 0;
1423         gdp = NULL;
1424
1425         smp_rmb();
1426         for (i = 0; i < ngroups; i++) {
1427                 gdp = ext3_get_group_desc(sb, i, NULL);
1428                 if (!gdp)
1429                         continue;
1430                 desc_count += le16_to_cpu(gdp->bg_free_blocks_count);
1431                 brelse(bitmap_bh);
1432                 bitmap_bh = read_block_bitmap(sb, i);
1433                 if (bitmap_bh == NULL)
1434                         continue;
1435
1436                 x = ext3_count_free(bitmap_bh, sb->s_blocksize);
1437                 printk("group %d: stored = %d, counted = %lu\n",
1438                         i, le16_to_cpu(gdp->bg_free_blocks_count), x);
1439                 bitmap_count += x;
1440         }
1441         brelse(bitmap_bh);
1442         printk("ext3_count_free_blocks: stored = %u, computed = %lu, %lu\n",
1443                le32_to_cpu(es->s_free_blocks_count), desc_count, bitmap_count);
1444         return bitmap_count;
1445 #else
1446         desc_count = 0;
1447         smp_rmb();
1448         for (i = 0; i < ngroups; i++) {
1449                 gdp = ext3_get_group_desc(sb, i, NULL);
1450                 if (!gdp)
1451                         continue;
1452                 desc_count += le16_to_cpu(gdp->bg_free_blocks_count);
1453         }
1454
1455         return desc_count;
1456 #endif
1457 }
1458
1459 static inline int
1460 block_in_use(unsigned long block, struct super_block *sb, unsigned char *map)
1461 {
1462         return ext3_test_bit ((block -
1463                 le32_to_cpu(EXT3_SB(sb)->s_es->s_first_data_block)) %
1464                          EXT3_BLOCKS_PER_GROUP(sb), map);
1465 }
1466
1467 static inline int test_root(int a, int b)
1468 {
1469         int num = b;
1470
1471         while (a > num)
1472                 num *= b;
1473         return num == a;
1474 }
1475
1476 static int ext3_group_sparse(int group)
1477 {
1478         if (group <= 1)
1479                 return 1;
1480         if (!(group & 1))
1481                 return 0;
1482         return (test_root(group, 7) || test_root(group, 5) ||
1483                 test_root(group, 3));
1484 }
1485
1486 /**
1487  *      ext3_bg_has_super - number of blocks used by the superblock in group
1488  *      @sb: superblock for filesystem
1489  *      @group: group number to check
1490  *
1491  *      Return the number of blocks used by the superblock (primary or backup)
1492  *      in this group.  Currently this will be only 0 or 1.
1493  */
1494 int ext3_bg_has_super(struct super_block *sb, int group)
1495 {
1496         if (EXT3_HAS_RO_COMPAT_FEATURE(sb,EXT3_FEATURE_RO_COMPAT_SPARSE_SUPER)&&
1497             !ext3_group_sparse(group))
1498                 return 0;
1499         return 1;
1500 }
1501
1502 /**
1503  *      ext3_bg_num_gdb - number of blocks used by the group table in group
1504  *      @sb: superblock for filesystem
1505  *      @group: group number to check
1506  *
1507  *      Return the number of blocks used by the group descriptor table
1508  *      (primary or backup) in this group.  In the future there may be a
1509  *      different number of descriptor blocks in each group.
1510  */
1511 unsigned long ext3_bg_num_gdb(struct super_block *sb, int group)
1512 {
1513         if (EXT3_HAS_RO_COMPAT_FEATURE(sb,EXT3_FEATURE_RO_COMPAT_SPARSE_SUPER)&&
1514             !ext3_group_sparse(group))
1515                 return 0;
1516         return EXT3_SB(sb)->s_gdb_count;
1517 }
1518