blob: e463dca008e4a9ad16cb54ca2dcdba7ef1793168 [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
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/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
41struct 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 */
82static struct buffer_head *
83read_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));
97error_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
115static 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
122restart:
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
164static int
165goal_in_my_reservation(struct ext3_reserve_window *rsv, int goal,
166 unsigned int group, struct super_block * sb)
167{
168 unsigned long group_first_block, group_last_block;
169
170 group_first_block = le32_to_cpu(EXT3_SB(sb)->s_es->s_first_data_block) +
171 group * EXT3_BLOCKS_PER_GROUP(sb);
172 group_last_block = group_first_block + EXT3_BLOCKS_PER_GROUP(sb) - 1;
173
174 if ((rsv->_rsv_start > group_last_block) ||
175 (rsv->_rsv_end < group_first_block))
176 return 0;
177 if ((goal >= 0) && ((goal + group_first_block < rsv->_rsv_start)
178 || (goal + group_first_block > rsv->_rsv_end)))
179 return 0;
180 return 1;
181}
182
183/*
184 * Find the reserved window which includes the goal, or the previous one
185 * if the goal is not in any window.
186 * Returns NULL if there are no windows or if all windows start after the goal.
187 */
188static struct ext3_reserve_window_node *
189search_reserve_window(struct rb_root *root, unsigned long goal)
190{
191 struct rb_node *n = root->rb_node;
192 struct ext3_reserve_window_node *rsv;
193
194 if (!n)
195 return NULL;
196
197 do {
198 rsv = rb_entry(n, struct ext3_reserve_window_node, rsv_node);
199
200 if (goal < rsv->rsv_start)
201 n = n->rb_left;
202 else if (goal > rsv->rsv_end)
203 n = n->rb_right;
204 else
205 return rsv;
206 } while (n);
207 /*
208 * We've fallen off the end of the tree: the goal wasn't inside
209 * any particular node. OK, the previous node must be to one
210 * side of the interval containing the goal. If it's the RHS,
211 * we need to back up one.
212 */
213 if (rsv->rsv_start > goal) {
214 n = rb_prev(&rsv->rsv_node);
215 rsv = rb_entry(n, struct ext3_reserve_window_node, rsv_node);
216 }
217 return rsv;
218}
219
220void ext3_rsv_window_add(struct super_block *sb,
221 struct ext3_reserve_window_node *rsv)
222{
223 struct rb_root *root = &EXT3_SB(sb)->s_rsv_window_root;
224 struct rb_node *node = &rsv->rsv_node;
225 unsigned int start = rsv->rsv_start;
226
227 struct rb_node ** p = &root->rb_node;
228 struct rb_node * parent = NULL;
229 struct ext3_reserve_window_node *this;
230
231 while (*p)
232 {
233 parent = *p;
234 this = rb_entry(parent, struct ext3_reserve_window_node, rsv_node);
235
236 if (start < this->rsv_start)
237 p = &(*p)->rb_left;
238 else if (start > this->rsv_end)
239 p = &(*p)->rb_right;
240 else
241 BUG();
242 }
243
244 rb_link_node(node, parent, p);
245 rb_insert_color(node, root);
246}
247
248static void rsv_window_remove(struct super_block *sb,
249 struct ext3_reserve_window_node *rsv)
250{
251 rsv->rsv_start = EXT3_RESERVE_WINDOW_NOT_ALLOCATED;
252 rsv->rsv_end = EXT3_RESERVE_WINDOW_NOT_ALLOCATED;
253 rsv->rsv_alloc_hit = 0;
254 rb_erase(&rsv->rsv_node, &EXT3_SB(sb)->s_rsv_window_root);
255}
256
257static inline int rsv_is_empty(struct ext3_reserve_window *rsv)
258{
259 /* a valid reservation end block could not be 0 */
260 return (rsv->_rsv_end == EXT3_RESERVE_WINDOW_NOT_ALLOCATED);
261}
262void ext3_init_block_alloc_info(struct inode *inode)
263{
264 struct ext3_inode_info *ei = EXT3_I(inode);
265 struct ext3_block_alloc_info *block_i = ei->i_block_alloc_info;
266 struct super_block *sb = inode->i_sb;
267
268 block_i = kmalloc(sizeof(*block_i), GFP_NOFS);
269 if (block_i) {
270 struct ext3_reserve_window_node *rsv = &block_i->rsv_window_node;
271
272 rsv->rsv_start = EXT3_RESERVE_WINDOW_NOT_ALLOCATED;
273 rsv->rsv_end = EXT3_RESERVE_WINDOW_NOT_ALLOCATED;
274
275 /*
276 * if filesystem is mounted with NORESERVATION, the goal
277 * reservation window size is set to zero to indicate
278 * block reservation is off
279 */
280 if (!test_opt(sb, RESERVATION))
281 rsv->rsv_goal_size = 0;
282 else
283 rsv->rsv_goal_size = EXT3_DEFAULT_RESERVE_BLOCKS;
284 rsv->rsv_alloc_hit = 0;
285 block_i->last_alloc_logical_block = 0;
286 block_i->last_alloc_physical_block = 0;
287 }
288 ei->i_block_alloc_info = block_i;
289}
290
291void ext3_discard_reservation(struct inode *inode)
292{
293 struct ext3_inode_info *ei = EXT3_I(inode);
294 struct ext3_block_alloc_info *block_i = ei->i_block_alloc_info;
295 struct ext3_reserve_window_node *rsv;
296 spinlock_t *rsv_lock = &EXT3_SB(inode->i_sb)->s_rsv_window_lock;
297
298 if (!block_i)
299 return;
300
301 rsv = &block_i->rsv_window_node;
302 if (!rsv_is_empty(&rsv->rsv_window)) {
303 spin_lock(rsv_lock);
304 if (!rsv_is_empty(&rsv->rsv_window))
305 rsv_window_remove(inode->i_sb, rsv);
306 spin_unlock(rsv_lock);
307 }
308}
309
310/* Free given blocks, update quota and i_blocks field */
311void ext3_free_blocks_sb(handle_t *handle, struct super_block *sb,
312 unsigned long block, unsigned long count,
313 int *pdquot_freed_blocks)
314{
315 struct buffer_head *bitmap_bh = NULL;
316 struct buffer_head *gd_bh;
317 unsigned long block_group;
318 unsigned long bit;
319 unsigned long i;
320 unsigned long overflow;
321 struct ext3_group_desc * desc;
322 struct ext3_super_block * es;
323 struct ext3_sb_info *sbi;
324 int err = 0, ret;
325 unsigned group_freed;
326
327 *pdquot_freed_blocks = 0;
328 sbi = EXT3_SB(sb);
329 es = sbi->s_es;
330 if (block < le32_to_cpu(es->s_first_data_block) ||
331 block + count < block ||
332 block + count > le32_to_cpu(es->s_blocks_count)) {
333 ext3_error (sb, "ext3_free_blocks",
334 "Freeing blocks not in datazone - "
335 "block = %lu, count = %lu", block, count);
336 goto error_return;
337 }
338
339 ext3_debug ("freeing block(s) %lu-%lu\n", block, block + count - 1);
340
341do_more:
342 overflow = 0;
343 block_group = (block - le32_to_cpu(es->s_first_data_block)) /
344 EXT3_BLOCKS_PER_GROUP(sb);
345 bit = (block - le32_to_cpu(es->s_first_data_block)) %
346 EXT3_BLOCKS_PER_GROUP(sb);
347 /*
348 * Check to see if we are freeing blocks across a group
349 * boundary.
350 */
351 if (bit + count > EXT3_BLOCKS_PER_GROUP(sb)) {
352 overflow = bit + count - EXT3_BLOCKS_PER_GROUP(sb);
353 count -= overflow;
354 }
355 brelse(bitmap_bh);
356 bitmap_bh = read_block_bitmap(sb, block_group);
357 if (!bitmap_bh)
358 goto error_return;
359 desc = ext3_get_group_desc (sb, block_group, &gd_bh);
360 if (!desc)
361 goto error_return;
362
363 if (in_range (le32_to_cpu(desc->bg_block_bitmap), block, count) ||
364 in_range (le32_to_cpu(desc->bg_inode_bitmap), block, count) ||
365 in_range (block, le32_to_cpu(desc->bg_inode_table),
366 sbi->s_itb_per_group) ||
367 in_range (block + count - 1, le32_to_cpu(desc->bg_inode_table),
368 sbi->s_itb_per_group))
369 ext3_error (sb, "ext3_free_blocks",
370 "Freeing blocks in system zones - "
371 "Block = %lu, count = %lu",
372 block, count);
373
374 /*
375 * We are about to start releasing blocks in the bitmap,
376 * so we need undo access.
377 */
378 /* @@@ check errors */
379 BUFFER_TRACE(bitmap_bh, "getting undo access");
380 err = ext3_journal_get_undo_access(handle, bitmap_bh);
381 if (err)
382 goto error_return;
383
384 /*
385 * We are about to modify some metadata. Call the journal APIs
386 * to unshare ->b_data if a currently-committing transaction is
387 * using it
388 */
389 BUFFER_TRACE(gd_bh, "get_write_access");
390 err = ext3_journal_get_write_access(handle, gd_bh);
391 if (err)
392 goto error_return;
393
394 jbd_lock_bh_state(bitmap_bh);
395
396 for (i = 0, group_freed = 0; i < count; i++) {
397 /*
398 * An HJ special. This is expensive...
399 */
400#ifdef CONFIG_JBD_DEBUG
401 jbd_unlock_bh_state(bitmap_bh);
402 {
403 struct buffer_head *debug_bh;
404 debug_bh = sb_find_get_block(sb, block + i);
405 if (debug_bh) {
406 BUFFER_TRACE(debug_bh, "Deleted!");
407 if (!bh2jh(bitmap_bh)->b_committed_data)
408 BUFFER_TRACE(debug_bh,
409 "No commited data in bitmap");
410 BUFFER_TRACE2(debug_bh, bitmap_bh, "bitmap");
411 __brelse(debug_bh);
412 }
413 }
414 jbd_lock_bh_state(bitmap_bh);
415#endif
416 if (need_resched()) {
417 jbd_unlock_bh_state(bitmap_bh);
418 cond_resched();
419 jbd_lock_bh_state(bitmap_bh);
420 }
421 /* @@@ This prevents newly-allocated data from being
422 * freed and then reallocated within the same
423 * transaction.
424 *
425 * Ideally we would want to allow that to happen, but to
426 * do so requires making journal_forget() capable of
427 * revoking the queued write of a data block, which
428 * implies blocking on the journal lock. *forget()
429 * cannot block due to truncate races.
430 *
431 * Eventually we can fix this by making journal_forget()
432 * return a status indicating whether or not it was able
433 * to revoke the buffer. On successful revoke, it is
434 * safe not to set the allocation bit in the committed
435 * bitmap, because we know that there is no outstanding
436 * activity on the buffer any more and so it is safe to
437 * reallocate it.
438 */
439 BUFFER_TRACE(bitmap_bh, "set in b_committed_data");
440 J_ASSERT_BH(bitmap_bh,
441 bh2jh(bitmap_bh)->b_committed_data != NULL);
442 ext3_set_bit_atomic(sb_bgl_lock(sbi, block_group), bit + i,
443 bh2jh(bitmap_bh)->b_committed_data);
444
445 /*
446 * We clear the bit in the bitmap after setting the committed
447 * data bit, because this is the reverse order to that which
448 * the allocator uses.
449 */
450 BUFFER_TRACE(bitmap_bh, "clear bit");
451 if (!ext3_clear_bit_atomic(sb_bgl_lock(sbi, block_group),
452 bit + i, bitmap_bh->b_data)) {
453 jbd_unlock_bh_state(bitmap_bh);
454 ext3_error(sb, __FUNCTION__,
455 "bit already cleared for block %lu", 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;
487error_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 */
494void ext3_free_blocks(handle_t *handle, struct inode *inode,
495 unsigned long block, unsigned long count)
496{
497 struct super_block * sb;
498 int 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 */
527static int ext3_test_allocatable(int 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
544static int
545bitmap_search_next_usable_block(int start, struct buffer_head *bh,
546 int maxblocks)
547{
548 int 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 */
578static int
579find_next_usable_block(int start, struct buffer_head *bh, int maxblocks)
580{
581 int here, next;
582 char *p, *r;
583
584 if (start > 0) {
585 /*
586 * The goal was occupied; search forward for a free
587 * block within the next XX blocks.
588 *
589 * end_goal is more or less random, but it has to be
590 * less than EXT3_BLOCKS_PER_GROUP. Aligning up to the
591 * next 64-bit boundary is simple..
592 */
593 int end_goal = (start + 63) & ~63;
594 if (end_goal > maxblocks)
595 end_goal = maxblocks;
596 here = ext3_find_next_zero_bit(bh->b_data, end_goal, start);
597 if (here < end_goal && ext3_test_allocatable(here, bh))
598 return here;
599 ext3_debug("Bit not found near goal\n");
600 }
601
602 here = start;
603 if (here < 0)
604 here = 0;
605
606 p = ((char *)bh->b_data) + (here >> 3);
607 r = memscan(p, 0, (maxblocks - here + 7) >> 3);
608 next = (r - ((char *)bh->b_data)) << 3;
609
610 if (next < maxblocks && next >= start && ext3_test_allocatable(next, bh))
611 return next;
612
613 /*
614 * The bitmap search --- search forward alternately through the actual
615 * bitmap and the last-committed copy until we find a bit free in
616 * both
617 */
618 here = bitmap_search_next_usable_block(here, bh, maxblocks);
619 return here;
620}
621
622/*
623 * We think we can allocate this block in this bitmap. Try to set the bit.
624 * If that succeeds then check that nobody has allocated and then freed the
625 * block since we saw that is was not marked in b_committed_data. If it _was_
626 * allocated and freed then clear the bit in the bitmap again and return
627 * zero (failure).
628 */
629static inline int
630claim_block(spinlock_t *lock, int block, struct buffer_head *bh)
631{
632 struct journal_head *jh = bh2jh(bh);
633 int ret;
634
635 if (ext3_set_bit_atomic(lock, block, bh->b_data))
636 return 0;
637 jbd_lock_bh_state(bh);
638 if (jh->b_committed_data && ext3_test_bit(block,jh->b_committed_data)) {
639 ext3_clear_bit_atomic(lock, block, bh->b_data);
640 ret = 0;
641 } else {
642 ret = 1;
643 }
644 jbd_unlock_bh_state(bh);
645 return ret;
646}
647
648/*
649 * If we failed to allocate the desired block then we may end up crossing to a
650 * new bitmap. In that case we must release write access to the old one via
651 * ext3_journal_release_buffer(), else we'll run out of credits.
652 */
653static int
654ext3_try_to_allocate(struct super_block *sb, handle_t *handle, int group,
655 struct buffer_head *bitmap_bh, int goal, struct ext3_reserve_window *my_rsv)
656{
657 int group_first_block, start, end;
658
659 /* we do allocation within the reservation window if we have a window */
660 if (my_rsv) {
661 group_first_block =
662 le32_to_cpu(EXT3_SB(sb)->s_es->s_first_data_block) +
663 group * EXT3_BLOCKS_PER_GROUP(sb);
664 if (my_rsv->_rsv_start >= group_first_block)
665 start = my_rsv->_rsv_start - group_first_block;
666 else
667 /* reservation window cross group boundary */
668 start = 0;
669 end = my_rsv->_rsv_end - group_first_block + 1;
670 if (end > EXT3_BLOCKS_PER_GROUP(sb))
671 /* reservation window crosses group boundary */
672 end = EXT3_BLOCKS_PER_GROUP(sb);
673 if ((start <= goal) && (goal < end))
674 start = goal;
675 else
676 goal = -1;
677 } else {
678 if (goal > 0)
679 start = goal;
680 else
681 start = 0;
682 end = EXT3_BLOCKS_PER_GROUP(sb);
683 }
684
685 BUG_ON(start > EXT3_BLOCKS_PER_GROUP(sb));
686
687repeat:
688 if (goal < 0 || !ext3_test_allocatable(goal, bitmap_bh)) {
689 goal = find_next_usable_block(start, bitmap_bh, end);
690 if (goal < 0)
691 goto fail_access;
692 if (!my_rsv) {
693 int i;
694
695 for (i = 0; i < 7 && goal > start &&
696 ext3_test_allocatable(goal - 1,
697 bitmap_bh);
698 i++, goal--)
699 ;
700 }
701 }
702 start = goal;
703
704 if (!claim_block(sb_bgl_lock(EXT3_SB(sb), group), goal, bitmap_bh)) {
705 /*
706 * The block was allocated by another thread, or it was
707 * allocated and then freed by another thread
708 */
709 start++;
710 goal++;
711 if (start >= end)
712 goto fail_access;
713 goto repeat;
714 }
715 return goal;
716fail_access:
717 return -1;
718}
719
720/**
721 * find_next_reservable_window():
722 * find a reservable space within the given range.
723 * It does not allocate the reservation window for now:
724 * alloc_new_reservation() will do the work later.
725 *
726 * @search_head: the head of the searching list;
727 * This is not necessarily the list head of the whole filesystem
728 *
729 * We have both head and start_block to assist the search
730 * for the reservable space. The list starts from head,
731 * but we will shift to the place where start_block is,
732 * then start from there, when looking for a reservable space.
733 *
734 * @size: the target new reservation window size
735 *
736 * @group_first_block: the first block we consider to start
737 * the real search from
738 *
739 * @last_block:
740 * the maximum block number that our goal reservable space
741 * could start from. This is normally the last block in this
742 * group. The search will end when we found the start of next
743 * possible reservable space is out of this boundary.
744 * This could handle the cross boundary reservation window
745 * request.
746 *
747 * basically we search from the given range, rather than the whole
748 * reservation double linked list, (start_block, last_block)
749 * to find a free region that is of my size and has not
750 * been reserved.
751 *
Linus Torvalds1da177e2005-04-16 15:20:36 -0700752 */
Mingming Cao21fe3472005-06-28 20:45:16 -0700753static int find_next_reservable_window(
Linus Torvalds1da177e2005-04-16 15:20:36 -0700754 struct ext3_reserve_window_node *search_head,
Mingming Cao21fe3472005-06-28 20:45:16 -0700755 struct ext3_reserve_window_node *my_rsv,
756 struct super_block * sb, int start_block,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700757 int last_block)
758{
759 struct rb_node *next;
760 struct ext3_reserve_window_node *rsv, *prev;
761 int cur;
Mingming Cao21fe3472005-06-28 20:45:16 -0700762 int size = my_rsv->rsv_goal_size;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700763
764 /* TODO: make the start of the reservation window byte-aligned */
765 /* cur = *start_block & ~7;*/
Mingming Cao21fe3472005-06-28 20:45:16 -0700766 cur = start_block;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700767 rsv = search_head;
768 if (!rsv)
Mingming Cao21fe3472005-06-28 20:45:16 -0700769 return -1;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700770
771 while (1) {
772 if (cur <= rsv->rsv_end)
773 cur = rsv->rsv_end + 1;
774
775 /* TODO?
776 * in the case we could not find a reservable space
777 * that is what is expected, during the re-search, we could
778 * remember what's the largest reservable space we could have
779 * and return that one.
780 *
781 * For now it will fail if we could not find the reservable
782 * space with expected-size (or more)...
783 */
784 if (cur > last_block)
Mingming Cao21fe3472005-06-28 20:45:16 -0700785 return -1; /* fail */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700786
787 prev = rsv;
788 next = rb_next(&rsv->rsv_node);
Mingming Cao21fe3472005-06-28 20:45:16 -0700789 rsv = list_entry(next,struct ext3_reserve_window_node,rsv_node);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700790
791 /*
792 * Reached the last reservation, we can just append to the
793 * previous one.
794 */
795 if (!next)
796 break;
797
798 if (cur + size <= rsv->rsv_start) {
799 /*
800 * Found a reserveable space big enough. We could
801 * have a reservation across the group boundary here
802 */
803 break;
804 }
805 }
806 /*
807 * we come here either :
808 * when we reach the end of the whole list,
809 * and there is empty reservable space after last entry in the list.
810 * append it to the end of the list.
811 *
812 * or we found one reservable space in the middle of the list,
813 * return the reservation window that we could append to.
814 * succeed.
815 */
Mingming Cao21fe3472005-06-28 20:45:16 -0700816
817 if ((prev != my_rsv) && (!rsv_is_empty(&my_rsv->rsv_window)))
818 rsv_window_remove(sb, my_rsv);
819
820 /*
821 * Let's book the whole avaliable window for now. We will check the
822 * disk bitmap later and then, if there are free blocks then we adjust
823 * the window size if it's larger than requested.
824 * Otherwise, we will remove this node from the tree next time
825 * call find_next_reservable_window.
826 */
827 my_rsv->rsv_start = cur;
828 my_rsv->rsv_end = cur + size - 1;
829 my_rsv->rsv_alloc_hit = 0;
830
831 if (prev != my_rsv)
832 ext3_rsv_window_add(sb, my_rsv);
833
834 return 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700835}
836
837/**
838 * alloc_new_reservation()--allocate a new reservation window
839 *
840 * To make a new reservation, we search part of the filesystem
841 * reservation list (the list that inside the group). We try to
842 * allocate a new reservation window near the allocation goal,
843 * or the beginning of the group, if there is no goal.
844 *
845 * We first find a reservable space after the goal, then from
846 * there, we check the bitmap for the first free block after
847 * it. If there is no free block until the end of group, then the
848 * whole group is full, we failed. Otherwise, check if the free
849 * block is inside the expected reservable space, if so, we
850 * succeed.
851 * If the first free block is outside the reservable space, then
852 * start from the first free block, we search for next available
853 * space, and go on.
854 *
855 * on succeed, a new reservation will be found and inserted into the list
856 * It contains at least one free block, and it does not overlap with other
857 * reservation windows.
858 *
859 * failed: we failed to find a reservation window in this group
860 *
861 * @rsv: the reservation
862 *
863 * @goal: The goal (group-relative). It is where the search for a
864 * free reservable space should start from.
865 * if we have a goal(goal >0 ), then start from there,
866 * no goal(goal = -1), we start from the first block
867 * of the group.
868 *
869 * @sb: the super block
870 * @group: the group we are trying to allocate in
871 * @bitmap_bh: the block group block bitmap
Mingming Cao21fe3472005-06-28 20:45:16 -0700872 *
Linus Torvalds1da177e2005-04-16 15:20:36 -0700873 */
874static int alloc_new_reservation(struct ext3_reserve_window_node *my_rsv,
875 int goal, struct super_block *sb,
876 unsigned int group, struct buffer_head *bitmap_bh)
877{
878 struct ext3_reserve_window_node *search_head;
879 int group_first_block, group_end_block, start_block;
880 int first_free_block;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700881 struct rb_root *fs_rsv_root = &EXT3_SB(sb)->s_rsv_window_root;
882 unsigned long size;
Mingming Cao21fe3472005-06-28 20:45:16 -0700883 int ret;
884 spinlock_t *rsv_lock = &EXT3_SB(sb)->s_rsv_window_lock;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700885
886 group_first_block = le32_to_cpu(EXT3_SB(sb)->s_es->s_first_data_block) +
887 group * EXT3_BLOCKS_PER_GROUP(sb);
888 group_end_block = group_first_block + EXT3_BLOCKS_PER_GROUP(sb) - 1;
889
890 if (goal < 0)
891 start_block = group_first_block;
892 else
893 start_block = goal + group_first_block;
894
895 size = my_rsv->rsv_goal_size;
Mingming Cao21fe3472005-06-28 20:45:16 -0700896
Linus Torvalds1da177e2005-04-16 15:20:36 -0700897 if (!rsv_is_empty(&my_rsv->rsv_window)) {
898 /*
899 * if the old reservation is cross group boundary
900 * and if the goal is inside the old reservation window,
901 * we will come here when we just failed to allocate from
902 * the first part of the window. We still have another part
903 * that belongs to the next group. In this case, there is no
904 * point to discard our window and try to allocate a new one
905 * in this group(which will fail). we should
906 * keep the reservation window, just simply move on.
907 *
908 * Maybe we could shift the start block of the reservation
909 * window to the first block of next group.
910 */
911
912 if ((my_rsv->rsv_start <= group_end_block) &&
913 (my_rsv->rsv_end > group_end_block) &&
914 (start_block >= my_rsv->rsv_start))
915 return -1;
916
917 if ((my_rsv->rsv_alloc_hit >
918 (my_rsv->rsv_end - my_rsv->rsv_start + 1) / 2)) {
919 /*
920 * if we previously allocation hit ration is greater than half
921 * we double the size of reservation window next time
922 * otherwise keep the same
923 */
924 size = size * 2;
925 if (size > EXT3_MAX_RESERVE_BLOCKS)
926 size = EXT3_MAX_RESERVE_BLOCKS;
927 my_rsv->rsv_goal_size= size;
928 }
929 }
Mingming Cao21fe3472005-06-28 20:45:16 -0700930
931 spin_lock(rsv_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700932 /*
933 * shift the search start to the window near the goal block
934 */
935 search_head = search_reserve_window(fs_rsv_root, start_block);
936
937 /*
938 * find_next_reservable_window() simply finds a reservable window
939 * inside the given range(start_block, group_end_block).
940 *
941 * To make sure the reservation window has a free bit inside it, we
942 * need to check the bitmap after we found a reservable window.
943 */
944retry:
Mingming Cao21fe3472005-06-28 20:45:16 -0700945 ret = find_next_reservable_window(search_head, my_rsv, sb,
946 start_block, group_end_block);
947
948 if (ret == -1) {
949 if (!rsv_is_empty(&my_rsv->rsv_window))
950 rsv_window_remove(sb, my_rsv);
951 spin_unlock(rsv_lock);
952 return -1;
953 }
954
Linus Torvalds1da177e2005-04-16 15:20:36 -0700955 /*
956 * On success, find_next_reservable_window() returns the
957 * reservation window where there is a reservable space after it.
958 * Before we reserve this reservable space, we need
959 * to make sure there is at least a free block inside this region.
960 *
961 * searching the first free bit on the block bitmap and copy of
962 * last committed bitmap alternatively, until we found a allocatable
963 * block. Search start from the start block of the reservable space
964 * we just found.
965 */
Mingming Cao21fe3472005-06-28 20:45:16 -0700966 spin_unlock(rsv_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700967 first_free_block = bitmap_search_next_usable_block(
Mingming Cao21fe3472005-06-28 20:45:16 -0700968 my_rsv->rsv_start - group_first_block,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700969 bitmap_bh, group_end_block - group_first_block + 1);
970
971 if (first_free_block < 0) {
972 /*
973 * no free block left on the bitmap, no point
974 * to reserve the space. return failed.
975 */
Mingming Cao21fe3472005-06-28 20:45:16 -0700976 spin_lock(rsv_lock);
977 if (!rsv_is_empty(&my_rsv->rsv_window))
978 rsv_window_remove(sb, my_rsv);
979 spin_unlock(rsv_lock);
980 return -1; /* failed */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700981 }
Mingming Cao21fe3472005-06-28 20:45:16 -0700982
Linus Torvalds1da177e2005-04-16 15:20:36 -0700983 start_block = first_free_block + group_first_block;
984 /*
985 * check if the first free block is within the
Mingming Cao21fe3472005-06-28 20:45:16 -0700986 * free space we just reserved
Linus Torvalds1da177e2005-04-16 15:20:36 -0700987 */
Mingming Cao21fe3472005-06-28 20:45:16 -0700988 if (start_block >= my_rsv->rsv_start && start_block < my_rsv->rsv_end)
989 return 0; /* success */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700990 /*
991 * if the first free bit we found is out of the reservable space
Mingming Cao21fe3472005-06-28 20:45:16 -0700992 * continue search for next reservable space,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700993 * start from where the free block is,
994 * we also shift the list head to where we stopped last time
995 */
Mingming Cao21fe3472005-06-28 20:45:16 -0700996 search_head = my_rsv;
997 spin_lock(rsv_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700998 goto retry;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700999}
1000
1001/*
1002 * This is the main function used to allocate a new block and its reservation
1003 * window.
1004 *
1005 * Each time when a new block allocation is need, first try to allocate from
1006 * its own reservation. If it does not have a reservation window, instead of
1007 * looking for a free bit on bitmap first, then look up the reservation list to
1008 * see if it is inside somebody else's reservation window, we try to allocate a
1009 * reservation window for it starting from the goal first. Then do the block
1010 * allocation within the reservation window.
1011 *
1012 * This will avoid keeping on searching the reservation list again and
1013 * again when someboday is looking for a free block (without
1014 * reservation), and there are lots of free blocks, but they are all
1015 * being reserved.
1016 *
1017 * We use a sorted double linked list for the per-filesystem reservation list.
1018 * The insert, remove and find a free space(non-reserved) operations for the
1019 * sorted double linked list should be fast.
1020 *
1021 */
1022static int
1023ext3_try_to_allocate_with_rsv(struct super_block *sb, handle_t *handle,
1024 unsigned int group, struct buffer_head *bitmap_bh,
1025 int goal, struct ext3_reserve_window_node * my_rsv,
1026 int *errp)
1027{
Linus Torvalds1da177e2005-04-16 15:20:36 -07001028 unsigned long group_first_block;
1029 int ret = 0;
1030 int fatal;
1031
1032 *errp = 0;
1033
1034 /*
1035 * Make sure we use undo access for the bitmap, because it is critical
1036 * that we do the frozen_data COW on bitmap buffers in all cases even
1037 * if the buffer is in BJ_Forget state in the committing transaction.
1038 */
1039 BUFFER_TRACE(bitmap_bh, "get undo access for new block");
1040 fatal = ext3_journal_get_undo_access(handle, bitmap_bh);
1041 if (fatal) {
1042 *errp = fatal;
1043 return -1;
1044 }
1045
1046 /*
1047 * we don't deal with reservation when
1048 * filesystem is mounted without reservation
1049 * or the file is not a regular file
1050 * or last attempt to allocate a block with reservation turned on failed
1051 */
1052 if (my_rsv == NULL ) {
1053 ret = ext3_try_to_allocate(sb, handle, group, bitmap_bh, goal, NULL);
1054 goto out;
1055 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001056 /*
1057 * goal is a group relative block number (if there is a goal)
1058 * 0 < goal < EXT3_BLOCKS_PER_GROUP(sb)
1059 * first block is a filesystem wide block number
1060 * first block is the block number of the first block in this group
1061 */
1062 group_first_block = le32_to_cpu(EXT3_SB(sb)->s_es->s_first_data_block) +
1063 group * EXT3_BLOCKS_PER_GROUP(sb);
1064
1065 /*
1066 * Basically we will allocate a new block from inode's reservation
1067 * window.
1068 *
1069 * We need to allocate a new reservation window, if:
1070 * a) inode does not have a reservation window; or
1071 * b) last attempt to allocate a block from existing reservation
1072 * failed; or
1073 * c) we come here with a goal and with a reservation window
1074 *
1075 * We do not need to allocate a new reservation window if we come here
1076 * at the beginning with a goal and the goal is inside the window, or
1077 * we don't have a goal but already have a reservation window.
1078 * then we could go to allocate from the reservation window directly.
1079 */
1080 while (1) {
Mingming Cao21fe3472005-06-28 20:45:16 -07001081 if (rsv_is_empty(&my_rsv->rsv_window) || (ret < 0) ||
1082 !goal_in_my_reservation(&my_rsv->rsv_window, goal, group, sb)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07001083 ret = alloc_new_reservation(my_rsv, goal, sb,
1084 group, bitmap_bh);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001085 if (ret < 0)
1086 break; /* failed */
1087
Mingming Cao21fe3472005-06-28 20:45:16 -07001088 if (!goal_in_my_reservation(&my_rsv->rsv_window, goal, group, sb))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001089 goal = -1;
1090 }
Mingming Cao21fe3472005-06-28 20:45:16 -07001091 if ((my_rsv->rsv_start >= group_first_block + EXT3_BLOCKS_PER_GROUP(sb))
1092 || (my_rsv->rsv_end < group_first_block))
Linus Torvalds1da177e2005-04-16 15:20:36 -07001093 BUG();
1094 ret = ext3_try_to_allocate(sb, handle, group, bitmap_bh, goal,
Mingming Cao21fe3472005-06-28 20:45:16 -07001095 &my_rsv->rsv_window);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001096 if (ret >= 0) {
1097 my_rsv->rsv_alloc_hit++;
1098 break; /* succeed */
1099 }
1100 }
1101out:
1102 if (ret >= 0) {
1103 BUFFER_TRACE(bitmap_bh, "journal_dirty_metadata for "
1104 "bitmap block");
1105 fatal = ext3_journal_dirty_metadata(handle, bitmap_bh);
1106 if (fatal) {
1107 *errp = fatal;
1108 return -1;
1109 }
1110 return ret;
1111 }
1112
1113 BUFFER_TRACE(bitmap_bh, "journal_release_buffer");
1114 ext3_journal_release_buffer(handle, bitmap_bh);
1115 return ret;
1116}
1117
1118static int ext3_has_free_blocks(struct ext3_sb_info *sbi)
1119{
1120 int free_blocks, root_blocks;
1121
1122 free_blocks = percpu_counter_read_positive(&sbi->s_freeblocks_counter);
1123 root_blocks = le32_to_cpu(sbi->s_es->s_r_blocks_count);
1124 if (free_blocks < root_blocks + 1 && !capable(CAP_SYS_RESOURCE) &&
1125 sbi->s_resuid != current->fsuid &&
1126 (sbi->s_resgid == 0 || !in_group_p (sbi->s_resgid))) {
1127 return 0;
1128 }
1129 return 1;
1130}
1131
1132/*
1133 * ext3_should_retry_alloc() is called when ENOSPC is returned, and if
1134 * it is profitable to retry the operation, this function will wait
1135 * for the current or commiting transaction to complete, and then
1136 * return TRUE.
1137 */
1138int ext3_should_retry_alloc(struct super_block *sb, int *retries)
1139{
1140 if (!ext3_has_free_blocks(EXT3_SB(sb)) || (*retries)++ > 3)
1141 return 0;
1142
1143 jbd_debug(1, "%s: retrying operation after ENOSPC\n", sb->s_id);
1144
1145 return journal_force_commit_nested(EXT3_SB(sb)->s_journal);
1146}
1147
1148/*
1149 * ext3_new_block uses a goal block to assist allocation. If the goal is
1150 * free, or there is a free block within 32 blocks of the goal, that block
1151 * is allocated. Otherwise a forward search is made for a free block; within
1152 * each block group the search first looks for an entire free byte in the block
1153 * bitmap, and then for any free bit if that fails.
1154 * This function also updates quota and i_blocks field.
1155 */
1156int ext3_new_block(handle_t *handle, struct inode *inode,
1157 unsigned long goal, int *errp)
1158{
1159 struct buffer_head *bitmap_bh = NULL;
1160 struct buffer_head *gdp_bh;
1161 int group_no;
1162 int goal_group;
1163 int ret_block;
1164 int bgi; /* blockgroup iteration index */
1165 int target_block;
1166 int fatal = 0, err;
1167 int performed_allocation = 0;
1168 int free_blocks;
1169 struct super_block *sb;
1170 struct ext3_group_desc *gdp;
1171 struct ext3_super_block *es;
1172 struct ext3_sb_info *sbi;
1173 struct ext3_reserve_window_node *my_rsv = NULL;
1174 struct ext3_block_alloc_info *block_i;
1175 unsigned short windowsz = 0;
1176#ifdef EXT3FS_DEBUG
1177 static int goal_hits, goal_attempts;
1178#endif
1179 unsigned long ngroups;
1180
1181 *errp = -ENOSPC;
1182 sb = inode->i_sb;
1183 if (!sb) {
1184 printk("ext3_new_block: nonexistent device");
1185 return 0;
1186 }
1187
1188 /*
1189 * Check quota for allocation of this block.
1190 */
1191 if (DQUOT_ALLOC_BLOCK(inode, 1)) {
1192 *errp = -EDQUOT;
1193 return 0;
1194 }
1195
1196 sbi = EXT3_SB(sb);
1197 es = EXT3_SB(sb)->s_es;
1198 ext3_debug("goal=%lu.\n", goal);
1199 /*
1200 * Allocate a block from reservation only when
1201 * filesystem is mounted with reservation(default,-o reservation), and
1202 * it's a regular file, and
1203 * the desired window size is greater than 0 (One could use ioctl
1204 * command EXT3_IOC_SETRSVSZ to set the window size to 0 to turn off
1205 * reservation on that particular file)
1206 */
1207 block_i = EXT3_I(inode)->i_block_alloc_info;
1208 if (block_i && ((windowsz = block_i->rsv_window_node.rsv_goal_size) > 0))
1209 my_rsv = &block_i->rsv_window_node;
1210
1211 if (!ext3_has_free_blocks(sbi)) {
1212 *errp = -ENOSPC;
1213 goto out;
1214 }
1215
1216 /*
1217 * First, test whether the goal block is free.
1218 */
1219 if (goal < le32_to_cpu(es->s_first_data_block) ||
1220 goal >= le32_to_cpu(es->s_blocks_count))
1221 goal = le32_to_cpu(es->s_first_data_block);
1222 group_no = (goal - le32_to_cpu(es->s_first_data_block)) /
1223 EXT3_BLOCKS_PER_GROUP(sb);
1224 gdp = ext3_get_group_desc(sb, group_no, &gdp_bh);
1225 if (!gdp)
1226 goto io_error;
1227
1228 goal_group = group_no;
1229retry:
1230 free_blocks = le16_to_cpu(gdp->bg_free_blocks_count);
1231 /*
1232 * if there is not enough free blocks to make a new resevation
1233 * turn off reservation for this allocation
1234 */
1235 if (my_rsv && (free_blocks < windowsz)
1236 && (rsv_is_empty(&my_rsv->rsv_window)))
1237 my_rsv = NULL;
1238
1239 if (free_blocks > 0) {
1240 ret_block = ((goal - le32_to_cpu(es->s_first_data_block)) %
1241 EXT3_BLOCKS_PER_GROUP(sb));
1242 bitmap_bh = read_block_bitmap(sb, group_no);
1243 if (!bitmap_bh)
1244 goto io_error;
1245 ret_block = ext3_try_to_allocate_with_rsv(sb, handle, group_no,
1246 bitmap_bh, ret_block, my_rsv, &fatal);
1247 if (fatal)
1248 goto out;
1249 if (ret_block >= 0)
1250 goto allocated;
1251 }
1252
1253 ngroups = EXT3_SB(sb)->s_groups_count;
1254 smp_rmb();
1255
1256 /*
1257 * Now search the rest of the groups. We assume that
1258 * i and gdp correctly point to the last group visited.
1259 */
1260 for (bgi = 0; bgi < ngroups; bgi++) {
1261 group_no++;
1262 if (group_no >= ngroups)
1263 group_no = 0;
1264 gdp = ext3_get_group_desc(sb, group_no, &gdp_bh);
1265 if (!gdp) {
1266 *errp = -EIO;
1267 goto out;
1268 }
1269 free_blocks = le16_to_cpu(gdp->bg_free_blocks_count);
1270 /*
1271 * skip this group if the number of
1272 * free blocks is less than half of the reservation
1273 * window size.
1274 */
1275 if (free_blocks <= (windowsz/2))
1276 continue;
1277
1278 brelse(bitmap_bh);
1279 bitmap_bh = read_block_bitmap(sb, group_no);
1280 if (!bitmap_bh)
1281 goto io_error;
1282 ret_block = ext3_try_to_allocate_with_rsv(sb, handle, group_no,
1283 bitmap_bh, -1, my_rsv, &fatal);
1284 if (fatal)
1285 goto out;
1286 if (ret_block >= 0)
1287 goto allocated;
1288 }
1289 /*
1290 * We may end up a bogus ealier ENOSPC error due to
1291 * filesystem is "full" of reservations, but
1292 * there maybe indeed free blocks avaliable on disk
1293 * In this case, we just forget about the reservations
1294 * just do block allocation as without reservations.
1295 */
1296 if (my_rsv) {
1297 my_rsv = NULL;
1298 group_no = goal_group;
1299 goto retry;
1300 }
1301 /* No space left on the device */
1302 *errp = -ENOSPC;
1303 goto out;
1304
1305allocated:
1306
1307 ext3_debug("using block group %d(%d)\n",
1308 group_no, gdp->bg_free_blocks_count);
1309
1310 BUFFER_TRACE(gdp_bh, "get_write_access");
1311 fatal = ext3_journal_get_write_access(handle, gdp_bh);
1312 if (fatal)
1313 goto out;
1314
1315 target_block = ret_block + group_no * EXT3_BLOCKS_PER_GROUP(sb)
1316 + le32_to_cpu(es->s_first_data_block);
1317
1318 if (target_block == le32_to_cpu(gdp->bg_block_bitmap) ||
1319 target_block == le32_to_cpu(gdp->bg_inode_bitmap) ||
1320 in_range(target_block, le32_to_cpu(gdp->bg_inode_table),
1321 EXT3_SB(sb)->s_itb_per_group))
1322 ext3_error(sb, "ext3_new_block",
1323 "Allocating block in system zone - "
1324 "block = %u", target_block);
1325
1326 performed_allocation = 1;
1327
1328#ifdef CONFIG_JBD_DEBUG
1329 {
1330 struct buffer_head *debug_bh;
1331
1332 /* Record bitmap buffer state in the newly allocated block */
1333 debug_bh = sb_find_get_block(sb, target_block);
1334 if (debug_bh) {
1335 BUFFER_TRACE(debug_bh, "state when allocated");
1336 BUFFER_TRACE2(debug_bh, bitmap_bh, "bitmap state");
1337 brelse(debug_bh);
1338 }
1339 }
1340 jbd_lock_bh_state(bitmap_bh);
1341 spin_lock(sb_bgl_lock(sbi, group_no));
1342 if (buffer_jbd(bitmap_bh) && bh2jh(bitmap_bh)->b_committed_data) {
1343 if (ext3_test_bit(ret_block,
1344 bh2jh(bitmap_bh)->b_committed_data)) {
1345 printk("%s: block was unexpectedly set in "
1346 "b_committed_data\n", __FUNCTION__);
1347 }
1348 }
1349 ext3_debug("found bit %d\n", ret_block);
1350 spin_unlock(sb_bgl_lock(sbi, group_no));
1351 jbd_unlock_bh_state(bitmap_bh);
1352#endif
1353
1354 /* ret_block was blockgroup-relative. Now it becomes fs-relative */
1355 ret_block = target_block;
1356
1357 if (ret_block >= le32_to_cpu(es->s_blocks_count)) {
1358 ext3_error(sb, "ext3_new_block",
1359 "block(%d) >= blocks count(%d) - "
1360 "block_group = %d, es == %p ", ret_block,
1361 le32_to_cpu(es->s_blocks_count), group_no, es);
1362 goto out;
1363 }
1364
1365 /*
1366 * It is up to the caller to add the new buffer to a journal
1367 * list of some description. We don't know in advance whether
1368 * the caller wants to use it as metadata or data.
1369 */
1370 ext3_debug("allocating block %d. Goal hits %d of %d.\n",
1371 ret_block, goal_hits, goal_attempts);
1372
1373 spin_lock(sb_bgl_lock(sbi, group_no));
1374 gdp->bg_free_blocks_count =
1375 cpu_to_le16(le16_to_cpu(gdp->bg_free_blocks_count) - 1);
1376 spin_unlock(sb_bgl_lock(sbi, group_no));
1377 percpu_counter_mod(&sbi->s_freeblocks_counter, -1);
1378
1379 BUFFER_TRACE(gdp_bh, "journal_dirty_metadata for group descriptor");
1380 err = ext3_journal_dirty_metadata(handle, gdp_bh);
1381 if (!fatal)
1382 fatal = err;
1383
1384 sb->s_dirt = 1;
1385 if (fatal)
1386 goto out;
1387
1388 *errp = 0;
1389 brelse(bitmap_bh);
1390 return ret_block;
1391
1392io_error:
1393 *errp = -EIO;
1394out:
1395 if (fatal) {
1396 *errp = fatal;
1397 ext3_std_error(sb, fatal);
1398 }
1399 /*
1400 * Undo the block allocation
1401 */
1402 if (!performed_allocation)
1403 DQUOT_FREE_BLOCK(inode, 1);
1404 brelse(bitmap_bh);
1405 return 0;
1406}
1407
1408unsigned long ext3_count_free_blocks(struct super_block *sb)
1409{
1410 unsigned long desc_count;
1411 struct ext3_group_desc *gdp;
1412 int i;
1413 unsigned long ngroups;
1414#ifdef EXT3FS_DEBUG
1415 struct ext3_super_block *es;
1416 unsigned long bitmap_count, x;
1417 struct buffer_head *bitmap_bh = NULL;
1418
1419 lock_super(sb);
1420 es = EXT3_SB(sb)->s_es;
1421 desc_count = 0;
1422 bitmap_count = 0;
1423 gdp = NULL;
1424 for (i = 0; i < EXT3_SB(sb)->s_groups_count; i++) {
1425 gdp = ext3_get_group_desc(sb, i, NULL);
1426 if (!gdp)
1427 continue;
1428 desc_count += le16_to_cpu(gdp->bg_free_blocks_count);
1429 brelse(bitmap_bh);
1430 bitmap_bh = read_block_bitmap(sb, i);
1431 if (bitmap_bh == NULL)
1432 continue;
1433
1434 x = ext3_count_free(bitmap_bh, sb->s_blocksize);
1435 printk("group %d: stored = %d, counted = %lu\n",
1436 i, le16_to_cpu(gdp->bg_free_blocks_count), x);
1437 bitmap_count += x;
1438 }
1439 brelse(bitmap_bh);
1440 printk("ext3_count_free_blocks: stored = %u, computed = %lu, %lu\n",
1441 le32_to_cpu(es->s_free_blocks_count), desc_count, bitmap_count);
1442 unlock_super(sb);
1443 return bitmap_count;
1444#else
1445 desc_count = 0;
1446 ngroups = EXT3_SB(sb)->s_groups_count;
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
1459static inline int
1460block_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
1467static 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
1476static 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 */
1494int 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 */
1511unsigned 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
1519#ifdef CONFIG_EXT3_CHECK
1520/* Called at mount-time, super-block is locked */
1521void ext3_check_blocks_bitmap (struct super_block * sb)
1522{
1523 struct ext3_super_block *es;
1524 unsigned long desc_count, bitmap_count, x, j;
1525 unsigned long desc_blocks;
1526 struct buffer_head *bitmap_bh = NULL;
1527 struct ext3_group_desc *gdp;
1528 int i;
1529
1530 es = EXT3_SB(sb)->s_es;
1531 desc_count = 0;
1532 bitmap_count = 0;
1533 gdp = NULL;
1534 for (i = 0; i < EXT3_SB(sb)->s_groups_count; i++) {
1535 gdp = ext3_get_group_desc (sb, i, NULL);
1536 if (!gdp)
1537 continue;
1538 desc_count += le16_to_cpu(gdp->bg_free_blocks_count);
1539 brelse(bitmap_bh);
1540 bitmap_bh = read_block_bitmap(sb, i);
1541 if (bitmap_bh == NULL)
1542 continue;
1543
1544 if (ext3_bg_has_super(sb, i) &&
1545 !ext3_test_bit(0, bitmap_bh->b_data))
1546 ext3_error(sb, __FUNCTION__,
1547 "Superblock in group %d is marked free", i);
1548
1549 desc_blocks = ext3_bg_num_gdb(sb, i);
1550 for (j = 0; j < desc_blocks; j++)
1551 if (!ext3_test_bit(j + 1, bitmap_bh->b_data))
1552 ext3_error(sb, __FUNCTION__,
1553 "Descriptor block #%ld in group "
1554 "%d is marked free", j, i);
1555
1556 if (!block_in_use (le32_to_cpu(gdp->bg_block_bitmap),
1557 sb, bitmap_bh->b_data))
1558 ext3_error (sb, "ext3_check_blocks_bitmap",
1559 "Block bitmap for group %d is marked free",
1560 i);
1561
1562 if (!block_in_use (le32_to_cpu(gdp->bg_inode_bitmap),
1563 sb, bitmap_bh->b_data))
1564 ext3_error (sb, "ext3_check_blocks_bitmap",
1565 "Inode bitmap for group %d is marked free",
1566 i);
1567
1568 for (j = 0; j < EXT3_SB(sb)->s_itb_per_group; j++)
1569 if (!block_in_use (le32_to_cpu(gdp->bg_inode_table) + j,
1570 sb, bitmap_bh->b_data))
1571 ext3_error (sb, "ext3_check_blocks_bitmap",
1572 "Block #%d of the inode table in "
1573 "group %d is marked free", j, i);
1574
1575 x = ext3_count_free(bitmap_bh, sb->s_blocksize);
1576 if (le16_to_cpu(gdp->bg_free_blocks_count) != x)
1577 ext3_error (sb, "ext3_check_blocks_bitmap",
1578 "Wrong free blocks count for group %d, "
1579 "stored = %d, counted = %lu", i,
1580 le16_to_cpu(gdp->bg_free_blocks_count), x);
1581 bitmap_count += x;
1582 }
1583 brelse(bitmap_bh);
1584 if (le32_to_cpu(es->s_free_blocks_count) != bitmap_count)
1585 ext3_error (sb, "ext3_check_blocks_bitmap",
1586 "Wrong free blocks count in super block, "
1587 "stored = %lu, counted = %lu",
1588 (unsigned long)le32_to_cpu(es->s_free_blocks_count),
1589 bitmap_count);
1590}
1591#endif