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-rw-r--r--fs/ext4/balloc.c1833
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diff --git a/fs/ext4/balloc.c b/fs/ext4/balloc.c
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1/*
2 * linux/fs/ext4/balloc.c
3 *
4 * Copyright (C) 1992, 1993, 1994, 1995
5 * Remy Card (card@masi.ibp.fr)
6 * Laboratoire MASI - Institut Blaise Pascal
7 * Universite Pierre et Marie Curie (Paris VI)
8 *
9 * Enhanced block allocation by Stephen Tweedie (sct@redhat.com), 1993
10 * Big-endian to little-endian byte-swapping/bitmaps by
11 * David S. Miller (davem@caip.rutgers.edu), 1995
12 */
13
14#include <linux/time.h>
15#include <linux/capability.h>
16#include <linux/fs.h>
17#include <linux/jbd2.h>
18#include <linux/ext4_fs.h>
19#include <linux/ext4_jbd2.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 * Calculate the block group number and offset, given a block number
29 */
30void ext4_get_group_no_and_offset(struct super_block *sb, ext4_fsblk_t blocknr,
31 unsigned long *blockgrpp, ext4_grpblk_t *offsetp)
32{
33 struct ext4_super_block *es = EXT4_SB(sb)->s_es;
34 ext4_grpblk_t offset;
35
36 blocknr = blocknr - le32_to_cpu(es->s_first_data_block);
37 offset = do_div(blocknr, EXT4_BLOCKS_PER_GROUP(sb));
38 if (offsetp)
39 *offsetp = offset;
40 if (blockgrpp)
41 *blockgrpp = blocknr;
42
43}
44
45/*
46 * The free blocks are managed by bitmaps. A file system contains several
47 * blocks groups. Each group contains 1 bitmap block for blocks, 1 bitmap
48 * block for inodes, N blocks for the inode table and data blocks.
49 *
50 * The file system contains group descriptors which are located after the
51 * super block. Each descriptor contains the number of the bitmap block and
52 * the free blocks count in the block. The descriptors are loaded in memory
53 * when a file system is mounted (see ext4_read_super).
54 */
55
56
57#define in_range(b, first, len) ((b) >= (first) && (b) <= (first) + (len) - 1)
58
59/**
60 * ext4_get_group_desc() -- load group descriptor from disk
61 * @sb: super block
62 * @block_group: given block group
63 * @bh: pointer to the buffer head to store the block
64 * group descriptor
65 */
66struct ext4_group_desc * ext4_get_group_desc(struct super_block * sb,
67 unsigned int block_group,
68 struct buffer_head ** bh)
69{
70 unsigned long group_desc;
71 unsigned long offset;
72 struct ext4_group_desc * desc;
73 struct ext4_sb_info *sbi = EXT4_SB(sb);
74
75 if (block_group >= sbi->s_groups_count) {
76 ext4_error (sb, "ext4_get_group_desc",
77 "block_group >= groups_count - "
78 "block_group = %d, groups_count = %lu",
79 block_group, sbi->s_groups_count);
80
81 return NULL;
82 }
83 smp_rmb();
84
85 group_desc = block_group >> EXT4_DESC_PER_BLOCK_BITS(sb);
86 offset = block_group & (EXT4_DESC_PER_BLOCK(sb) - 1);
87 if (!sbi->s_group_desc[group_desc]) {
88 ext4_error (sb, "ext4_get_group_desc",
89 "Group descriptor not loaded - "
90 "block_group = %d, group_desc = %lu, desc = %lu",
91 block_group, group_desc, offset);
92 return NULL;
93 }
94
95 desc = (struct ext4_group_desc *)(
96 (__u8 *)sbi->s_group_desc[group_desc]->b_data +
97 offset * EXT4_DESC_SIZE(sb));
98 if (bh)
99 *bh = sbi->s_group_desc[group_desc];
100 return desc;
101}
102
103/**
104 * read_block_bitmap()
105 * @sb: super block
106 * @block_group: given block group
107 *
108 * Read the bitmap for a given block_group, reading into the specified
109 * slot in the superblock's bitmap cache.
110 *
111 * Return buffer_head on success or NULL in case of failure.
112 */
113static struct buffer_head *
114read_block_bitmap(struct super_block *sb, unsigned int block_group)
115{
116 struct ext4_group_desc * desc;
117 struct buffer_head * bh = NULL;
118
119 desc = ext4_get_group_desc (sb, block_group, NULL);
120 if (!desc)
121 goto error_out;
122 bh = sb_bread(sb, ext4_block_bitmap(sb, desc));
123 if (!bh)
124 ext4_error (sb, "read_block_bitmap",
125 "Cannot read block bitmap - "
126 "block_group = %d, block_bitmap = %llu",
127 block_group,
128 ext4_block_bitmap(sb, desc));
129error_out:
130 return bh;
131}
132/*
133 * The reservation window structure operations
134 * --------------------------------------------
135 * Operations include:
136 * dump, find, add, remove, is_empty, find_next_reservable_window, etc.
137 *
138 * We use a red-black tree to represent per-filesystem reservation
139 * windows.
140 *
141 */
142
143/**
144 * __rsv_window_dump() -- Dump the filesystem block allocation reservation map
145 * @rb_root: root of per-filesystem reservation rb tree
146 * @verbose: verbose mode
147 * @fn: function which wishes to dump the reservation map
148 *
149 * If verbose is turned on, it will print the whole block reservation
150 * windows(start, end). Otherwise, it will only print out the "bad" windows,
151 * those windows that overlap with their immediate neighbors.
152 */
153#if 1
154static void __rsv_window_dump(struct rb_root *root, int verbose,
155 const char *fn)
156{
157 struct rb_node *n;
158 struct ext4_reserve_window_node *rsv, *prev;
159 int bad;
160
161restart:
162 n = rb_first(root);
163 bad = 0;
164 prev = NULL;
165
166 printk("Block Allocation Reservation Windows Map (%s):\n", fn);
167 while (n) {
168 rsv = list_entry(n, struct ext4_reserve_window_node, rsv_node);
169 if (verbose)
170 printk("reservation window 0x%p "
171 "start: %llu, end: %llu\n",
172 rsv, rsv->rsv_start, rsv->rsv_end);
173 if (rsv->rsv_start && rsv->rsv_start >= rsv->rsv_end) {
174 printk("Bad reservation %p (start >= end)\n",
175 rsv);
176 bad = 1;
177 }
178 if (prev && prev->rsv_end >= rsv->rsv_start) {
179 printk("Bad reservation %p (prev->end >= start)\n",
180 rsv);
181 bad = 1;
182 }
183 if (bad) {
184 if (!verbose) {
185 printk("Restarting reservation walk in verbose mode\n");
186 verbose = 1;
187 goto restart;
188 }
189 }
190 n = rb_next(n);
191 prev = rsv;
192 }
193 printk("Window map complete.\n");
194 if (bad)
195 BUG();
196}
197#define rsv_window_dump(root, verbose) \
198 __rsv_window_dump((root), (verbose), __FUNCTION__)
199#else
200#define rsv_window_dump(root, verbose) do {} while (0)
201#endif
202
203/**
204 * goal_in_my_reservation()
205 * @rsv: inode's reservation window
206 * @grp_goal: given goal block relative to the allocation block group
207 * @group: the current allocation block group
208 * @sb: filesystem super block
209 *
210 * Test if the given goal block (group relative) is within the file's
211 * own block reservation window range.
212 *
213 * If the reservation window is outside the goal allocation group, return 0;
214 * grp_goal (given goal block) could be -1, which means no specific
215 * goal block. In this case, always return 1.
216 * If the goal block is within the reservation window, return 1;
217 * otherwise, return 0;
218 */
219static int
220goal_in_my_reservation(struct ext4_reserve_window *rsv, ext4_grpblk_t grp_goal,
221 unsigned int group, struct super_block * sb)
222{
223 ext4_fsblk_t group_first_block, group_last_block;
224
225 group_first_block = ext4_group_first_block_no(sb, group);
226 group_last_block = group_first_block + (EXT4_BLOCKS_PER_GROUP(sb) - 1);
227
228 if ((rsv->_rsv_start > group_last_block) ||
229 (rsv->_rsv_end < group_first_block))
230 return 0;
231 if ((grp_goal >= 0) && ((grp_goal + group_first_block < rsv->_rsv_start)
232 || (grp_goal + group_first_block > rsv->_rsv_end)))
233 return 0;
234 return 1;
235}
236
237/**
238 * search_reserve_window()
239 * @rb_root: root of reservation tree
240 * @goal: target allocation block
241 *
242 * Find the reserved window which includes the goal, or the previous one
243 * if the goal is not in any window.
244 * Returns NULL if there are no windows or if all windows start after the goal.
245 */
246static struct ext4_reserve_window_node *
247search_reserve_window(struct rb_root *root, ext4_fsblk_t goal)
248{
249 struct rb_node *n = root->rb_node;
250 struct ext4_reserve_window_node *rsv;
251
252 if (!n)
253 return NULL;
254
255 do {
256 rsv = rb_entry(n, struct ext4_reserve_window_node, rsv_node);
257
258 if (goal < rsv->rsv_start)
259 n = n->rb_left;
260 else if (goal > rsv->rsv_end)
261 n = n->rb_right;
262 else
263 return rsv;
264 } while (n);
265 /*
266 * We've fallen off the end of the tree: the goal wasn't inside
267 * any particular node. OK, the previous node must be to one
268 * side of the interval containing the goal. If it's the RHS,
269 * we need to back up one.
270 */
271 if (rsv->rsv_start > goal) {
272 n = rb_prev(&rsv->rsv_node);
273 rsv = rb_entry(n, struct ext4_reserve_window_node, rsv_node);
274 }
275 return rsv;
276}
277
278/**
279 * ext4_rsv_window_add() -- Insert a window to the block reservation rb tree.
280 * @sb: super block
281 * @rsv: reservation window to add
282 *
283 * Must be called with rsv_lock hold.
284 */
285void ext4_rsv_window_add(struct super_block *sb,
286 struct ext4_reserve_window_node *rsv)
287{
288 struct rb_root *root = &EXT4_SB(sb)->s_rsv_window_root;
289 struct rb_node *node = &rsv->rsv_node;
290 ext4_fsblk_t start = rsv->rsv_start;
291
292 struct rb_node ** p = &root->rb_node;
293 struct rb_node * parent = NULL;
294 struct ext4_reserve_window_node *this;
295
296 while (*p)
297 {
298 parent = *p;
299 this = rb_entry(parent, struct ext4_reserve_window_node, rsv_node);
300
301 if (start < this->rsv_start)
302 p = &(*p)->rb_left;
303 else if (start > this->rsv_end)
304 p = &(*p)->rb_right;
305 else {
306 rsv_window_dump(root, 1);
307 BUG();
308 }
309 }
310
311 rb_link_node(node, parent, p);
312 rb_insert_color(node, root);
313}
314
315/**
316 * ext4_rsv_window_remove() -- unlink a window from the reservation rb tree
317 * @sb: super block
318 * @rsv: reservation window to remove
319 *
320 * Mark the block reservation window as not allocated, and unlink it
321 * from the filesystem reservation window rb tree. Must be called with
322 * rsv_lock hold.
323 */
324static void rsv_window_remove(struct super_block *sb,
325 struct ext4_reserve_window_node *rsv)
326{
327 rsv->rsv_start = EXT4_RESERVE_WINDOW_NOT_ALLOCATED;
328 rsv->rsv_end = EXT4_RESERVE_WINDOW_NOT_ALLOCATED;
329 rsv->rsv_alloc_hit = 0;
330 rb_erase(&rsv->rsv_node, &EXT4_SB(sb)->s_rsv_window_root);
331}
332
333/*
334 * rsv_is_empty() -- Check if the reservation window is allocated.
335 * @rsv: given reservation window to check
336 *
337 * returns 1 if the end block is EXT4_RESERVE_WINDOW_NOT_ALLOCATED.
338 */
339static inline int rsv_is_empty(struct ext4_reserve_window *rsv)
340{
341 /* a valid reservation end block could not be 0 */
342 return rsv->_rsv_end == EXT4_RESERVE_WINDOW_NOT_ALLOCATED;
343}
344
345/**
346 * ext4_init_block_alloc_info()
347 * @inode: file inode structure
348 *
349 * Allocate and initialize the reservation window structure, and
350 * link the window to the ext4 inode structure at last
351 *
352 * The reservation window structure is only dynamically allocated
353 * and linked to ext4 inode the first time the open file
354 * needs a new block. So, before every ext4_new_block(s) call, for
355 * regular files, we should check whether the reservation window
356 * structure exists or not. In the latter case, this function is called.
357 * Fail to do so will result in block reservation being turned off for that
358 * open file.
359 *
360 * This function is called from ext4_get_blocks_handle(), also called
361 * when setting the reservation window size through ioctl before the file
362 * is open for write (needs block allocation).
363 *
364 * Needs truncate_mutex protection prior to call this function.
365 */
366void ext4_init_block_alloc_info(struct inode *inode)
367{
368 struct ext4_inode_info *ei = EXT4_I(inode);
369 struct ext4_block_alloc_info *block_i = ei->i_block_alloc_info;
370 struct super_block *sb = inode->i_sb;
371
372 block_i = kmalloc(sizeof(*block_i), GFP_NOFS);
373 if (block_i) {
374 struct ext4_reserve_window_node *rsv = &block_i->rsv_window_node;
375
376 rsv->rsv_start = EXT4_RESERVE_WINDOW_NOT_ALLOCATED;
377 rsv->rsv_end = EXT4_RESERVE_WINDOW_NOT_ALLOCATED;
378
379 /*
380 * if filesystem is mounted with NORESERVATION, the goal
381 * reservation window size is set to zero to indicate
382 * block reservation is off
383 */
384 if (!test_opt(sb, RESERVATION))
385 rsv->rsv_goal_size = 0;
386 else
387 rsv->rsv_goal_size = EXT4_DEFAULT_RESERVE_BLOCKS;
388 rsv->rsv_alloc_hit = 0;
389 block_i->last_alloc_logical_block = 0;
390 block_i->last_alloc_physical_block = 0;
391 }
392 ei->i_block_alloc_info = block_i;
393}
394
395/**
396 * ext4_discard_reservation()
397 * @inode: inode
398 *
399 * Discard(free) block reservation window on last file close, or truncate
400 * or at last iput().
401 *
402 * It is being called in three cases:
403 * ext4_release_file(): last writer close the file
404 * ext4_clear_inode(): last iput(), when nobody link to this file.
405 * ext4_truncate(): when the block indirect map is about to change.
406 *
407 */
408void ext4_discard_reservation(struct inode *inode)
409{
410 struct ext4_inode_info *ei = EXT4_I(inode);
411 struct ext4_block_alloc_info *block_i = ei->i_block_alloc_info;
412 struct ext4_reserve_window_node *rsv;
413 spinlock_t *rsv_lock = &EXT4_SB(inode->i_sb)->s_rsv_window_lock;
414
415 if (!block_i)
416 return;
417
418 rsv = &block_i->rsv_window_node;
419 if (!rsv_is_empty(&rsv->rsv_window)) {
420 spin_lock(rsv_lock);
421 if (!rsv_is_empty(&rsv->rsv_window))
422 rsv_window_remove(inode->i_sb, rsv);
423 spin_unlock(rsv_lock);
424 }
425}
426
427/**
428 * ext4_free_blocks_sb() -- Free given blocks and update quota
429 * @handle: handle to this transaction
430 * @sb: super block
431 * @block: start physcial block to free
432 * @count: number of blocks to free
433 * @pdquot_freed_blocks: pointer to quota
434 */
435void ext4_free_blocks_sb(handle_t *handle, struct super_block *sb,
436 ext4_fsblk_t block, unsigned long count,
437 unsigned long *pdquot_freed_blocks)
438{
439 struct buffer_head *bitmap_bh = NULL;
440 struct buffer_head *gd_bh;
441 unsigned long block_group;
442 ext4_grpblk_t bit;
443 unsigned long i;
444 unsigned long overflow;
445 struct ext4_group_desc * desc;
446 struct ext4_super_block * es;
447 struct ext4_sb_info *sbi;
448 int err = 0, ret;
449 ext4_grpblk_t group_freed;
450
451 *pdquot_freed_blocks = 0;
452 sbi = EXT4_SB(sb);
453 es = sbi->s_es;
454 if (block < le32_to_cpu(es->s_first_data_block) ||
455 block + count < block ||
456 block + count > ext4_blocks_count(es)) {
457 ext4_error (sb, "ext4_free_blocks",
458 "Freeing blocks not in datazone - "
459 "block = %llu, count = %lu", block, count);
460 goto error_return;
461 }
462
463 ext4_debug ("freeing block(s) %llu-%llu\n", block, block + count - 1);
464
465do_more:
466 overflow = 0;
467 ext4_get_group_no_and_offset(sb, block, &block_group, &bit);
468 /*
469 * Check to see if we are freeing blocks across a group
470 * boundary.
471 */
472 if (bit + count > EXT4_BLOCKS_PER_GROUP(sb)) {
473 overflow = bit + count - EXT4_BLOCKS_PER_GROUP(sb);
474 count -= overflow;
475 }
476 brelse(bitmap_bh);
477 bitmap_bh = read_block_bitmap(sb, block_group);
478 if (!bitmap_bh)
479 goto error_return;
480 desc = ext4_get_group_desc (sb, block_group, &gd_bh);
481 if (!desc)
482 goto error_return;
483
484 if (in_range(ext4_block_bitmap(sb, desc), block, count) ||
485 in_range(ext4_inode_bitmap(sb, desc), block, count) ||
486 in_range(block, ext4_inode_table(sb, desc), sbi->s_itb_per_group) ||
487 in_range(block + count - 1, ext4_inode_table(sb, desc),
488 sbi->s_itb_per_group))
489 ext4_error (sb, "ext4_free_blocks",
490 "Freeing blocks in system zones - "
491 "Block = %llu, count = %lu",
492 block, count);
493
494 /*
495 * We are about to start releasing blocks in the bitmap,
496 * so we need undo access.
497 */
498 /* @@@ check errors */
499 BUFFER_TRACE(bitmap_bh, "getting undo access");
500 err = ext4_journal_get_undo_access(handle, bitmap_bh);
501 if (err)
502 goto error_return;
503
504 /*
505 * We are about to modify some metadata. Call the journal APIs
506 * to unshare ->b_data if a currently-committing transaction is
507 * using it
508 */
509 BUFFER_TRACE(gd_bh, "get_write_access");
510 err = ext4_journal_get_write_access(handle, gd_bh);
511 if (err)
512 goto error_return;
513
514 jbd_lock_bh_state(bitmap_bh);
515
516 for (i = 0, group_freed = 0; i < count; i++) {
517 /*
518 * An HJ special. This is expensive...
519 */
520#ifdef CONFIG_JBD_DEBUG
521 jbd_unlock_bh_state(bitmap_bh);
522 {
523 struct buffer_head *debug_bh;
524 debug_bh = sb_find_get_block(sb, block + i);
525 if (debug_bh) {
526 BUFFER_TRACE(debug_bh, "Deleted!");
527 if (!bh2jh(bitmap_bh)->b_committed_data)
528 BUFFER_TRACE(debug_bh,
529 "No commited data in bitmap");
530 BUFFER_TRACE2(debug_bh, bitmap_bh, "bitmap");
531 __brelse(debug_bh);
532 }
533 }
534 jbd_lock_bh_state(bitmap_bh);
535#endif
536 if (need_resched()) {
537 jbd_unlock_bh_state(bitmap_bh);
538 cond_resched();
539 jbd_lock_bh_state(bitmap_bh);
540 }
541 /* @@@ This prevents newly-allocated data from being
542 * freed and then reallocated within the same
543 * transaction.
544 *
545 * Ideally we would want to allow that to happen, but to
546 * do so requires making jbd2_journal_forget() capable of
547 * revoking the queued write of a data block, which
548 * implies blocking on the journal lock. *forget()
549 * cannot block due to truncate races.
550 *
551 * Eventually we can fix this by making jbd2_journal_forget()
552 * return a status indicating whether or not it was able
553 * to revoke the buffer. On successful revoke, it is
554 * safe not to set the allocation bit in the committed
555 * bitmap, because we know that there is no outstanding
556 * activity on the buffer any more and so it is safe to
557 * reallocate it.
558 */
559 BUFFER_TRACE(bitmap_bh, "set in b_committed_data");
560 J_ASSERT_BH(bitmap_bh,
561 bh2jh(bitmap_bh)->b_committed_data != NULL);
562 ext4_set_bit_atomic(sb_bgl_lock(sbi, block_group), bit + i,
563 bh2jh(bitmap_bh)->b_committed_data);
564
565 /*
566 * We clear the bit in the bitmap after setting the committed
567 * data bit, because this is the reverse order to that which
568 * the allocator uses.
569 */
570 BUFFER_TRACE(bitmap_bh, "clear bit");
571 if (!ext4_clear_bit_atomic(sb_bgl_lock(sbi, block_group),
572 bit + i, bitmap_bh->b_data)) {
573 jbd_unlock_bh_state(bitmap_bh);
574 ext4_error(sb, __FUNCTION__,
575 "bit already cleared for block %llu",
576 (ext4_fsblk_t)(block + i));
577 jbd_lock_bh_state(bitmap_bh);
578 BUFFER_TRACE(bitmap_bh, "bit already cleared");
579 } else {
580 group_freed++;
581 }
582 }
583 jbd_unlock_bh_state(bitmap_bh);
584
585 spin_lock(sb_bgl_lock(sbi, block_group));
586 desc->bg_free_blocks_count =
587 cpu_to_le16(le16_to_cpu(desc->bg_free_blocks_count) +
588 group_freed);
589 spin_unlock(sb_bgl_lock(sbi, block_group));
590 percpu_counter_mod(&sbi->s_freeblocks_counter, count);
591
592 /* We dirtied the bitmap block */
593 BUFFER_TRACE(bitmap_bh, "dirtied bitmap block");
594 err = ext4_journal_dirty_metadata(handle, bitmap_bh);
595
596 /* And the group descriptor block */
597 BUFFER_TRACE(gd_bh, "dirtied group descriptor block");
598 ret = ext4_journal_dirty_metadata(handle, gd_bh);
599 if (!err) err = ret;
600 *pdquot_freed_blocks += group_freed;
601
602 if (overflow && !err) {
603 block += count;
604 count = overflow;
605 goto do_more;
606 }
607 sb->s_dirt = 1;
608error_return:
609 brelse(bitmap_bh);
610 ext4_std_error(sb, err);
611 return;
612}
613
614/**
615 * ext4_free_blocks() -- Free given blocks and update quota
616 * @handle: handle for this transaction
617 * @inode: inode
618 * @block: start physical block to free
619 * @count: number of blocks to count
620 */
621void ext4_free_blocks(handle_t *handle, struct inode *inode,
622 ext4_fsblk_t block, unsigned long count)
623{
624 struct super_block * sb;
625 unsigned long dquot_freed_blocks;
626
627 sb = inode->i_sb;
628 if (!sb) {
629 printk ("ext4_free_blocks: nonexistent device");
630 return;
631 }
632 ext4_free_blocks_sb(handle, sb, block, count, &dquot_freed_blocks);
633 if (dquot_freed_blocks)
634 DQUOT_FREE_BLOCK(inode, dquot_freed_blocks);
635 return;
636}
637
638/**
639 * ext4_test_allocatable()
640 * @nr: given allocation block group
641 * @bh: bufferhead contains the bitmap of the given block group
642 *
643 * For ext4 allocations, we must not reuse any blocks which are
644 * allocated in the bitmap buffer's "last committed data" copy. This
645 * prevents deletes from freeing up the page for reuse until we have
646 * committed the delete transaction.
647 *
648 * If we didn't do this, then deleting something and reallocating it as
649 * data would allow the old block to be overwritten before the
650 * transaction committed (because we force data to disk before commit).
651 * This would lead to corruption if we crashed between overwriting the
652 * data and committing the delete.
653 *
654 * @@@ We may want to make this allocation behaviour conditional on
655 * data-writes at some point, and disable it for metadata allocations or
656 * sync-data inodes.
657 */
658static int ext4_test_allocatable(ext4_grpblk_t nr, struct buffer_head *bh)
659{
660 int ret;
661 struct journal_head *jh = bh2jh(bh);
662
663 if (ext4_test_bit(nr, bh->b_data))
664 return 0;
665
666 jbd_lock_bh_state(bh);
667 if (!jh->b_committed_data)
668 ret = 1;
669 else
670 ret = !ext4_test_bit(nr, jh->b_committed_data);
671 jbd_unlock_bh_state(bh);
672 return ret;
673}
674
675/**
676 * bitmap_search_next_usable_block()
677 * @start: the starting block (group relative) of the search
678 * @bh: bufferhead contains the block group bitmap
679 * @maxblocks: the ending block (group relative) of the reservation
680 *
681 * The bitmap search --- search forward alternately through the actual
682 * bitmap on disk and the last-committed copy in journal, until we find a
683 * bit free in both bitmaps.
684 */
685static ext4_grpblk_t
686bitmap_search_next_usable_block(ext4_grpblk_t start, struct buffer_head *bh,
687 ext4_grpblk_t maxblocks)
688{
689 ext4_grpblk_t next;
690 struct journal_head *jh = bh2jh(bh);
691
692 while (start < maxblocks) {
693 next = ext4_find_next_zero_bit(bh->b_data, maxblocks, start);
694 if (next >= maxblocks)
695 return -1;
696 if (ext4_test_allocatable(next, bh))
697 return next;
698 jbd_lock_bh_state(bh);
699 if (jh->b_committed_data)
700 start = ext4_find_next_zero_bit(jh->b_committed_data,
701 maxblocks, next);
702 jbd_unlock_bh_state(bh);
703 }
704 return -1;
705}
706
707/**
708 * find_next_usable_block()
709 * @start: the starting block (group relative) to find next
710 * allocatable block in bitmap.
711 * @bh: bufferhead contains the block group bitmap
712 * @maxblocks: the ending block (group relative) for the search
713 *
714 * Find an allocatable block in a bitmap. We honor both the bitmap and
715 * its last-committed copy (if that exists), and perform the "most
716 * appropriate allocation" algorithm of looking for a free block near
717 * the initial goal; then for a free byte somewhere in the bitmap; then
718 * for any free bit in the bitmap.
719 */
720static ext4_grpblk_t
721find_next_usable_block(ext4_grpblk_t start, struct buffer_head *bh,
722 ext4_grpblk_t maxblocks)
723{
724 ext4_grpblk_t here, next;
725 char *p, *r;
726
727 if (start > 0) {
728 /*
729 * The goal was occupied; search forward for a free
730 * block within the next XX blocks.
731 *
732 * end_goal is more or less random, but it has to be
733 * less than EXT4_BLOCKS_PER_GROUP. Aligning up to the
734 * next 64-bit boundary is simple..
735 */
736 ext4_grpblk_t end_goal = (start + 63) & ~63;
737 if (end_goal > maxblocks)
738 end_goal = maxblocks;
739 here = ext4_find_next_zero_bit(bh->b_data, end_goal, start);
740 if (here < end_goal && ext4_test_allocatable(here, bh))
741 return here;
742 ext4_debug("Bit not found near goal\n");
743 }
744
745 here = start;
746 if (here < 0)
747 here = 0;
748
749 p = ((char *)bh->b_data) + (here >> 3);
750 r = memscan(p, 0, (maxblocks - here + 7) >> 3);
751 next = (r - ((char *)bh->b_data)) << 3;
752
753 if (next < maxblocks && next >= start && ext4_test_allocatable(next, bh))
754 return next;
755
756 /*
757 * The bitmap search --- search forward alternately through the actual
758 * bitmap and the last-committed copy until we find a bit free in
759 * both
760 */
761 here = bitmap_search_next_usable_block(here, bh, maxblocks);
762 return here;
763}
764
765/**
766 * claim_block()
767 * @block: the free block (group relative) to allocate
768 * @bh: the bufferhead containts the block group bitmap
769 *
770 * We think we can allocate this block in this bitmap. Try to set the bit.
771 * If that succeeds then check that nobody has allocated and then freed the
772 * block since we saw that is was not marked in b_committed_data. If it _was_
773 * allocated and freed then clear the bit in the bitmap again and return
774 * zero (failure).
775 */
776static inline int
777claim_block(spinlock_t *lock, ext4_grpblk_t block, struct buffer_head *bh)
778{
779 struct journal_head *jh = bh2jh(bh);
780 int ret;
781
782 if (ext4_set_bit_atomic(lock, block, bh->b_data))
783 return 0;
784 jbd_lock_bh_state(bh);
785 if (jh->b_committed_data && ext4_test_bit(block,jh->b_committed_data)) {
786 ext4_clear_bit_atomic(lock, block, bh->b_data);
787 ret = 0;
788 } else {
789 ret = 1;
790 }
791 jbd_unlock_bh_state(bh);
792 return ret;
793}
794
795/**
796 * ext4_try_to_allocate()
797 * @sb: superblock
798 * @handle: handle to this transaction
799 * @group: given allocation block group
800 * @bitmap_bh: bufferhead holds the block bitmap
801 * @grp_goal: given target block within the group
802 * @count: target number of blocks to allocate
803 * @my_rsv: reservation window
804 *
805 * Attempt to allocate blocks within a give range. Set the range of allocation
806 * first, then find the first free bit(s) from the bitmap (within the range),
807 * and at last, allocate the blocks by claiming the found free bit as allocated.
808 *
809 * To set the range of this allocation:
810 * if there is a reservation window, only try to allocate block(s) from the
811 * file's own reservation window;
812 * Otherwise, the allocation range starts from the give goal block, ends at
813 * the block group's last block.
814 *
815 * If we failed to allocate the desired block then we may end up crossing to a
816 * new bitmap. In that case we must release write access to the old one via
817 * ext4_journal_release_buffer(), else we'll run out of credits.
818 */
819static ext4_grpblk_t
820ext4_try_to_allocate(struct super_block *sb, handle_t *handle, int group,
821 struct buffer_head *bitmap_bh, ext4_grpblk_t grp_goal,
822 unsigned long *count, struct ext4_reserve_window *my_rsv)
823{
824 ext4_fsblk_t group_first_block;
825 ext4_grpblk_t start, end;
826 unsigned long num = 0;
827
828 /* we do allocation within the reservation window if we have a window */
829 if (my_rsv) {
830 group_first_block = ext4_group_first_block_no(sb, group);
831 if (my_rsv->_rsv_start >= group_first_block)
832 start = my_rsv->_rsv_start - group_first_block;
833 else
834 /* reservation window cross group boundary */
835 start = 0;
836 end = my_rsv->_rsv_end - group_first_block + 1;
837 if (end > EXT4_BLOCKS_PER_GROUP(sb))
838 /* reservation window crosses group boundary */
839 end = EXT4_BLOCKS_PER_GROUP(sb);
840 if ((start <= grp_goal) && (grp_goal < end))
841 start = grp_goal;
842 else
843 grp_goal = -1;
844 } else {
845 if (grp_goal > 0)
846 start = grp_goal;
847 else
848 start = 0;
849 end = EXT4_BLOCKS_PER_GROUP(sb);
850 }
851
852 BUG_ON(start > EXT4_BLOCKS_PER_GROUP(sb));
853
854repeat:
855 if (grp_goal < 0 || !ext4_test_allocatable(grp_goal, bitmap_bh)) {
856 grp_goal = find_next_usable_block(start, bitmap_bh, end);
857 if (grp_goal < 0)
858 goto fail_access;
859 if (!my_rsv) {
860 int i;
861
862 for (i = 0; i < 7 && grp_goal > start &&
863 ext4_test_allocatable(grp_goal - 1,
864 bitmap_bh);
865 i++, grp_goal--)
866 ;
867 }
868 }
869 start = grp_goal;
870
871 if (!claim_block(sb_bgl_lock(EXT4_SB(sb), group),
872 grp_goal, bitmap_bh)) {
873 /*
874 * The block was allocated by another thread, or it was
875 * allocated and then freed by another thread
876 */
877 start++;
878 grp_goal++;
879 if (start >= end)
880 goto fail_access;
881 goto repeat;
882 }
883 num++;
884 grp_goal++;
885 while (num < *count && grp_goal < end
886 && ext4_test_allocatable(grp_goal, bitmap_bh)
887 && claim_block(sb_bgl_lock(EXT4_SB(sb), group),
888 grp_goal, bitmap_bh)) {
889 num++;
890 grp_goal++;
891 }
892 *count = num;
893 return grp_goal - num;
894fail_access:
895 *count = num;
896 return -1;
897}
898
899/**
900 * find_next_reservable_window():
901 * find a reservable space within the given range.
902 * It does not allocate the reservation window for now:
903 * alloc_new_reservation() will do the work later.
904 *
905 * @search_head: the head of the searching list;
906 * This is not necessarily the list head of the whole filesystem
907 *
908 * We have both head and start_block to assist the search
909 * for the reservable space. The list starts from head,
910 * but we will shift to the place where start_block is,
911 * then start from there, when looking for a reservable space.
912 *
913 * @size: the target new reservation window size
914 *
915 * @group_first_block: the first block we consider to start
916 * the real search from
917 *
918 * @last_block:
919 * the maximum block number that our goal reservable space
920 * could start from. This is normally the last block in this
921 * group. The search will end when we found the start of next
922 * possible reservable space is out of this boundary.
923 * This could handle the cross boundary reservation window
924 * request.
925 *
926 * basically we search from the given range, rather than the whole
927 * reservation double linked list, (start_block, last_block)
928 * to find a free region that is of my size and has not
929 * been reserved.
930 *
931 */
932static int find_next_reservable_window(
933 struct ext4_reserve_window_node *search_head,
934 struct ext4_reserve_window_node *my_rsv,
935 struct super_block * sb,
936 ext4_fsblk_t start_block,
937 ext4_fsblk_t last_block)
938{
939 struct rb_node *next;
940 struct ext4_reserve_window_node *rsv, *prev;
941 ext4_fsblk_t cur;
942 int size = my_rsv->rsv_goal_size;
943
944 /* TODO: make the start of the reservation window byte-aligned */
945 /* cur = *start_block & ~7;*/
946 cur = start_block;
947 rsv = search_head;
948 if (!rsv)
949 return -1;
950
951 while (1) {
952 if (cur <= rsv->rsv_end)
953 cur = rsv->rsv_end + 1;
954
955 /* TODO?
956 * in the case we could not find a reservable space
957 * that is what is expected, during the re-search, we could
958 * remember what's the largest reservable space we could have
959 * and return that one.
960 *
961 * For now it will fail if we could not find the reservable
962 * space with expected-size (or more)...
963 */
964 if (cur > last_block)
965 return -1; /* fail */
966
967 prev = rsv;
968 next = rb_next(&rsv->rsv_node);
969 rsv = list_entry(next,struct ext4_reserve_window_node,rsv_node);
970
971 /*
972 * Reached the last reservation, we can just append to the
973 * previous one.
974 */
975 if (!next)
976 break;
977
978 if (cur + size <= rsv->rsv_start) {
979 /*
980 * Found a reserveable space big enough. We could
981 * have a reservation across the group boundary here
982 */
983 break;
984 }
985 }
986 /*
987 * we come here either :
988 * when we reach the end of the whole list,
989 * and there is empty reservable space after last entry in the list.
990 * append it to the end of the list.
991 *
992 * or we found one reservable space in the middle of the list,
993 * return the reservation window that we could append to.
994 * succeed.
995 */
996
997 if ((prev != my_rsv) && (!rsv_is_empty(&my_rsv->rsv_window)))
998 rsv_window_remove(sb, my_rsv);
999
1000 /*
1001 * Let's book the whole avaliable window for now. We will check the
1002 * disk bitmap later and then, if there are free blocks then we adjust
1003 * the window size if it's larger than requested.
1004 * Otherwise, we will remove this node from the tree next time
1005 * call find_next_reservable_window.
1006 */
1007 my_rsv->rsv_start = cur;
1008 my_rsv->rsv_end = cur + size - 1;
1009 my_rsv->rsv_alloc_hit = 0;
1010
1011 if (prev != my_rsv)
1012 ext4_rsv_window_add(sb, my_rsv);
1013
1014 return 0;
1015}
1016
1017/**
1018 * alloc_new_reservation()--allocate a new reservation window
1019 *
1020 * To make a new reservation, we search part of the filesystem
1021 * reservation list (the list that inside the group). We try to
1022 * allocate a new reservation window near the allocation goal,
1023 * or the beginning of the group, if there is no goal.
1024 *
1025 * We first find a reservable space after the goal, then from
1026 * there, we check the bitmap for the first free block after
1027 * it. If there is no free block until the end of group, then the
1028 * whole group is full, we failed. Otherwise, check if the free
1029 * block is inside the expected reservable space, if so, we
1030 * succeed.
1031 * If the first free block is outside the reservable space, then
1032 * start from the first free block, we search for next available
1033 * space, and go on.
1034 *
1035 * on succeed, a new reservation will be found and inserted into the list
1036 * It contains at least one free block, and it does not overlap with other
1037 * reservation windows.
1038 *
1039 * failed: we failed to find a reservation window in this group
1040 *
1041 * @rsv: the reservation
1042 *
1043 * @grp_goal: The goal (group-relative). It is where the search for a
1044 * free reservable space should start from.
1045 * if we have a grp_goal(grp_goal >0 ), then start from there,
1046 * no grp_goal(grp_goal = -1), we start from the first block
1047 * of the group.
1048 *
1049 * @sb: the super block
1050 * @group: the group we are trying to allocate in
1051 * @bitmap_bh: the block group block bitmap
1052 *
1053 */
1054static int alloc_new_reservation(struct ext4_reserve_window_node *my_rsv,
1055 ext4_grpblk_t grp_goal, struct super_block *sb,
1056 unsigned int group, struct buffer_head *bitmap_bh)
1057{
1058 struct ext4_reserve_window_node *search_head;
1059 ext4_fsblk_t group_first_block, group_end_block, start_block;
1060 ext4_grpblk_t first_free_block;
1061 struct rb_root *fs_rsv_root = &EXT4_SB(sb)->s_rsv_window_root;
1062 unsigned long size;
1063 int ret;
1064 spinlock_t *rsv_lock = &EXT4_SB(sb)->s_rsv_window_lock;
1065
1066 group_first_block = ext4_group_first_block_no(sb, group);
1067 group_end_block = group_first_block + (EXT4_BLOCKS_PER_GROUP(sb) - 1);
1068
1069 if (grp_goal < 0)
1070 start_block = group_first_block;
1071 else
1072 start_block = grp_goal + group_first_block;
1073
1074 size = my_rsv->rsv_goal_size;
1075
1076 if (!rsv_is_empty(&my_rsv->rsv_window)) {
1077 /*
1078 * if the old reservation is cross group boundary
1079 * and if the goal is inside the old reservation window,
1080 * we will come here when we just failed to allocate from
1081 * the first part of the window. We still have another part
1082 * that belongs to the next group. In this case, there is no
1083 * point to discard our window and try to allocate a new one
1084 * in this group(which will fail). we should
1085 * keep the reservation window, just simply move on.
1086 *
1087 * Maybe we could shift the start block of the reservation
1088 * window to the first block of next group.
1089 */
1090
1091 if ((my_rsv->rsv_start <= group_end_block) &&
1092 (my_rsv->rsv_end > group_end_block) &&
1093 (start_block >= my_rsv->rsv_start))
1094 return -1;
1095
1096 if ((my_rsv->rsv_alloc_hit >
1097 (my_rsv->rsv_end - my_rsv->rsv_start + 1) / 2)) {
1098 /*
1099 * if the previously allocation hit ratio is
1100 * greater than 1/2, then we double the size of
1101 * the reservation window the next time,
1102 * otherwise we keep the same size window
1103 */
1104 size = size * 2;
1105 if (size > EXT4_MAX_RESERVE_BLOCKS)
1106 size = EXT4_MAX_RESERVE_BLOCKS;
1107 my_rsv->rsv_goal_size= size;
1108 }
1109 }
1110
1111 spin_lock(rsv_lock);
1112 /*
1113 * shift the search start to the window near the goal block
1114 */
1115 search_head = search_reserve_window(fs_rsv_root, start_block);
1116
1117 /*
1118 * find_next_reservable_window() simply finds a reservable window
1119 * inside the given range(start_block, group_end_block).
1120 *
1121 * To make sure the reservation window has a free bit inside it, we
1122 * need to check the bitmap after we found a reservable window.
1123 */
1124retry:
1125 ret = find_next_reservable_window(search_head, my_rsv, sb,
1126 start_block, group_end_block);
1127
1128 if (ret == -1) {
1129 if (!rsv_is_empty(&my_rsv->rsv_window))
1130 rsv_window_remove(sb, my_rsv);
1131 spin_unlock(rsv_lock);
1132 return -1;
1133 }
1134
1135 /*
1136 * On success, find_next_reservable_window() returns the
1137 * reservation window where there is a reservable space after it.
1138 * Before we reserve this reservable space, we need
1139 * to make sure there is at least a free block inside this region.
1140 *
1141 * searching the first free bit on the block bitmap and copy of
1142 * last committed bitmap alternatively, until we found a allocatable
1143 * block. Search start from the start block of the reservable space
1144 * we just found.
1145 */
1146 spin_unlock(rsv_lock);
1147 first_free_block = bitmap_search_next_usable_block(
1148 my_rsv->rsv_start - group_first_block,
1149 bitmap_bh, group_end_block - group_first_block + 1);
1150
1151 if (first_free_block < 0) {
1152 /*
1153 * no free block left on the bitmap, no point
1154 * to reserve the space. return failed.
1155 */
1156 spin_lock(rsv_lock);
1157 if (!rsv_is_empty(&my_rsv->rsv_window))
1158 rsv_window_remove(sb, my_rsv);
1159 spin_unlock(rsv_lock);
1160 return -1; /* failed */
1161 }
1162
1163 start_block = first_free_block + group_first_block;
1164 /*
1165 * check if the first free block is within the
1166 * free space we just reserved
1167 */
1168 if (start_block >= my_rsv->rsv_start && start_block < my_rsv->rsv_end)
1169 return 0; /* success */
1170 /*
1171 * if the first free bit we found is out of the reservable space
1172 * continue search for next reservable space,
1173 * start from where the free block is,
1174 * we also shift the list head to where we stopped last time
1175 */
1176 search_head = my_rsv;
1177 spin_lock(rsv_lock);
1178 goto retry;
1179}
1180
1181/**
1182 * try_to_extend_reservation()
1183 * @my_rsv: given reservation window
1184 * @sb: super block
1185 * @size: the delta to extend
1186 *
1187 * Attempt to expand the reservation window large enough to have
1188 * required number of free blocks
1189 *
1190 * Since ext4_try_to_allocate() will always allocate blocks within
1191 * the reservation window range, if the window size is too small,
1192 * multiple blocks allocation has to stop at the end of the reservation
1193 * window. To make this more efficient, given the total number of
1194 * blocks needed and the current size of the window, we try to
1195 * expand the reservation window size if necessary on a best-effort
1196 * basis before ext4_new_blocks() tries to allocate blocks,
1197 */
1198static void try_to_extend_reservation(struct ext4_reserve_window_node *my_rsv,
1199 struct super_block *sb, int size)
1200{
1201 struct ext4_reserve_window_node *next_rsv;
1202 struct rb_node *next;
1203 spinlock_t *rsv_lock = &EXT4_SB(sb)->s_rsv_window_lock;
1204
1205 if (!spin_trylock(rsv_lock))
1206 return;
1207
1208 next = rb_next(&my_rsv->rsv_node);
1209
1210 if (!next)
1211 my_rsv->rsv_end += size;
1212 else {
1213 next_rsv = list_entry(next, struct ext4_reserve_window_node, rsv_node);
1214
1215 if ((next_rsv->rsv_start - my_rsv->rsv_end - 1) >= size)
1216 my_rsv->rsv_end += size;
1217 else
1218 my_rsv->rsv_end = next_rsv->rsv_start - 1;
1219 }
1220 spin_unlock(rsv_lock);
1221}
1222
1223/**
1224 * ext4_try_to_allocate_with_rsv()
1225 * @sb: superblock
1226 * @handle: handle to this transaction
1227 * @group: given allocation block group
1228 * @bitmap_bh: bufferhead holds the block bitmap
1229 * @grp_goal: given target block within the group
1230 * @count: target number of blocks to allocate
1231 * @my_rsv: reservation window
1232 * @errp: pointer to store the error code
1233 *
1234 * This is the main function used to allocate a new block and its reservation
1235 * window.
1236 *
1237 * Each time when a new block allocation is need, first try to allocate from
1238 * its own reservation. If it does not have a reservation window, instead of
1239 * looking for a free bit on bitmap first, then look up the reservation list to
1240 * see if it is inside somebody else's reservation window, we try to allocate a
1241 * reservation window for it starting from the goal first. Then do the block
1242 * allocation within the reservation window.
1243 *
1244 * This will avoid keeping on searching the reservation list again and
1245 * again when somebody is looking for a free block (without
1246 * reservation), and there are lots of free blocks, but they are all
1247 * being reserved.
1248 *
1249 * We use a red-black tree for the per-filesystem reservation list.
1250 *
1251 */
1252static ext4_grpblk_t
1253ext4_try_to_allocate_with_rsv(struct super_block *sb, handle_t *handle,
1254 unsigned int group, struct buffer_head *bitmap_bh,
1255 ext4_grpblk_t grp_goal,
1256 struct ext4_reserve_window_node * my_rsv,
1257 unsigned long *count, int *errp)
1258{
1259 ext4_fsblk_t group_first_block, group_last_block;
1260 ext4_grpblk_t ret = 0;
1261 int fatal;
1262 unsigned long num = *count;
1263
1264 *errp = 0;
1265
1266 /*
1267 * Make sure we use undo access for the bitmap, because it is critical
1268 * that we do the frozen_data COW on bitmap buffers in all cases even
1269 * if the buffer is in BJ_Forget state in the committing transaction.
1270 */
1271 BUFFER_TRACE(bitmap_bh, "get undo access for new block");
1272 fatal = ext4_journal_get_undo_access(handle, bitmap_bh);
1273 if (fatal) {
1274 *errp = fatal;
1275 return -1;
1276 }
1277
1278 /*
1279 * we don't deal with reservation when
1280 * filesystem is mounted without reservation
1281 * or the file is not a regular file
1282 * or last attempt to allocate a block with reservation turned on failed
1283 */
1284 if (my_rsv == NULL ) {
1285 ret = ext4_try_to_allocate(sb, handle, group, bitmap_bh,
1286 grp_goal, count, NULL);
1287 goto out;
1288 }
1289 /*
1290 * grp_goal is a group relative block number (if there is a goal)
1291 * 0 < grp_goal < EXT4_BLOCKS_PER_GROUP(sb)
1292 * first block is a filesystem wide block number
1293 * first block is the block number of the first block in this group
1294 */
1295 group_first_block = ext4_group_first_block_no(sb, group);
1296 group_last_block = group_first_block + (EXT4_BLOCKS_PER_GROUP(sb) - 1);
1297
1298 /*
1299 * Basically we will allocate a new block from inode's reservation
1300 * window.
1301 *
1302 * We need to allocate a new reservation window, if:
1303 * a) inode does not have a reservation window; or
1304 * b) last attempt to allocate a block from existing reservation
1305 * failed; or
1306 * c) we come here with a goal and with a reservation window
1307 *
1308 * We do not need to allocate a new reservation window if we come here
1309 * at the beginning with a goal and the goal is inside the window, or
1310 * we don't have a goal but already have a reservation window.
1311 * then we could go to allocate from the reservation window directly.
1312 */
1313 while (1) {
1314 if (rsv_is_empty(&my_rsv->rsv_window) || (ret < 0) ||
1315 !goal_in_my_reservation(&my_rsv->rsv_window,
1316 grp_goal, group, sb)) {
1317 if (my_rsv->rsv_goal_size < *count)
1318 my_rsv->rsv_goal_size = *count;
1319 ret = alloc_new_reservation(my_rsv, grp_goal, sb,
1320 group, bitmap_bh);
1321 if (ret < 0)
1322 break; /* failed */
1323
1324 if (!goal_in_my_reservation(&my_rsv->rsv_window,
1325 grp_goal, group, sb))
1326 grp_goal = -1;
1327 } else if (grp_goal > 0 &&
1328 (my_rsv->rsv_end-grp_goal+1) < *count)
1329 try_to_extend_reservation(my_rsv, sb,
1330 *count-my_rsv->rsv_end + grp_goal - 1);
1331
1332 if ((my_rsv->rsv_start > group_last_block) ||
1333 (my_rsv->rsv_end < group_first_block)) {
1334 rsv_window_dump(&EXT4_SB(sb)->s_rsv_window_root, 1);
1335 BUG();
1336 }
1337 ret = ext4_try_to_allocate(sb, handle, group, bitmap_bh,
1338 grp_goal, &num, &my_rsv->rsv_window);
1339 if (ret >= 0) {
1340 my_rsv->rsv_alloc_hit += num;
1341 *count = num;
1342 break; /* succeed */
1343 }
1344 num = *count;
1345 }
1346out:
1347 if (ret >= 0) {
1348 BUFFER_TRACE(bitmap_bh, "journal_dirty_metadata for "
1349 "bitmap block");
1350 fatal = ext4_journal_dirty_metadata(handle, bitmap_bh);
1351 if (fatal) {
1352 *errp = fatal;
1353 return -1;
1354 }
1355 return ret;
1356 }
1357
1358 BUFFER_TRACE(bitmap_bh, "journal_release_buffer");
1359 ext4_journal_release_buffer(handle, bitmap_bh);
1360 return ret;
1361}
1362
1363/**
1364 * ext4_has_free_blocks()
1365 * @sbi: in-core super block structure.
1366 *
1367 * Check if filesystem has at least 1 free block available for allocation.
1368 */
1369static int ext4_has_free_blocks(struct ext4_sb_info *sbi)
1370{
1371 ext4_fsblk_t free_blocks, root_blocks;
1372
1373 free_blocks = percpu_counter_read_positive(&sbi->s_freeblocks_counter);
1374 root_blocks = ext4_r_blocks_count(sbi->s_es);
1375 if (free_blocks < root_blocks + 1 && !capable(CAP_SYS_RESOURCE) &&
1376 sbi->s_resuid != current->fsuid &&
1377 (sbi->s_resgid == 0 || !in_group_p (sbi->s_resgid))) {
1378 return 0;
1379 }
1380 return 1;
1381}
1382
1383/**
1384 * ext4_should_retry_alloc()
1385 * @sb: super block
1386 * @retries number of attemps has been made
1387 *
1388 * ext4_should_retry_alloc() is called when ENOSPC is returned, and if
1389 * it is profitable to retry the operation, this function will wait
1390 * for the current or commiting transaction to complete, and then
1391 * return TRUE.
1392 *
1393 * if the total number of retries exceed three times, return FALSE.
1394 */
1395int ext4_should_retry_alloc(struct super_block *sb, int *retries)
1396{
1397 if (!ext4_has_free_blocks(EXT4_SB(sb)) || (*retries)++ > 3)
1398 return 0;
1399
1400 jbd_debug(1, "%s: retrying operation after ENOSPC\n", sb->s_id);
1401
1402 return jbd2_journal_force_commit_nested(EXT4_SB(sb)->s_journal);
1403}
1404
1405/**
1406 * ext4_new_blocks() -- core block(s) allocation function
1407 * @handle: handle to this transaction
1408 * @inode: file inode
1409 * @goal: given target block(filesystem wide)
1410 * @count: target number of blocks to allocate
1411 * @errp: error code
1412 *
1413 * ext4_new_blocks uses a goal block to assist allocation. It tries to
1414 * allocate block(s) from the block group contains the goal block first. If that
1415 * fails, it will try to allocate block(s) from other block groups without
1416 * any specific goal block.
1417 *
1418 */
1419ext4_fsblk_t ext4_new_blocks(handle_t *handle, struct inode *inode,
1420 ext4_fsblk_t goal, unsigned long *count, int *errp)
1421{
1422 struct buffer_head *bitmap_bh = NULL;
1423 struct buffer_head *gdp_bh;
1424 unsigned long group_no;
1425 int goal_group;
1426 ext4_grpblk_t grp_target_blk; /* blockgroup relative goal block */
1427 ext4_grpblk_t grp_alloc_blk; /* blockgroup-relative allocated block*/
1428 ext4_fsblk_t ret_block; /* filesyetem-wide allocated block */
1429 int bgi; /* blockgroup iteration index */
1430 int fatal = 0, err;
1431 int performed_allocation = 0;
1432 ext4_grpblk_t free_blocks; /* number of free blocks in a group */
1433 struct super_block *sb;
1434 struct ext4_group_desc *gdp;
1435 struct ext4_super_block *es;
1436 struct ext4_sb_info *sbi;
1437 struct ext4_reserve_window_node *my_rsv = NULL;
1438 struct ext4_block_alloc_info *block_i;
1439 unsigned short windowsz = 0;
1440#ifdef EXT4FS_DEBUG
1441 static int goal_hits, goal_attempts;
1442#endif
1443 unsigned long ngroups;
1444 unsigned long num = *count;
1445
1446 *errp = -ENOSPC;
1447 sb = inode->i_sb;
1448 if (!sb) {
1449 printk("ext4_new_block: nonexistent device");
1450 return 0;
1451 }
1452
1453 /*
1454 * Check quota for allocation of this block.
1455 */
1456 if (DQUOT_ALLOC_BLOCK(inode, num)) {
1457 *errp = -EDQUOT;
1458 return 0;
1459 }
1460
1461 sbi = EXT4_SB(sb);
1462 es = EXT4_SB(sb)->s_es;
1463 ext4_debug("goal=%lu.\n", goal);
1464 /*
1465 * Allocate a block from reservation only when
1466 * filesystem is mounted with reservation(default,-o reservation), and
1467 * it's a regular file, and
1468 * the desired window size is greater than 0 (One could use ioctl
1469 * command EXT4_IOC_SETRSVSZ to set the window size to 0 to turn off
1470 * reservation on that particular file)
1471 */
1472 block_i = EXT4_I(inode)->i_block_alloc_info;
1473 if (block_i && ((windowsz = block_i->rsv_window_node.rsv_goal_size) > 0))
1474 my_rsv = &block_i->rsv_window_node;
1475
1476 if (!ext4_has_free_blocks(sbi)) {
1477 *errp = -ENOSPC;
1478 goto out;
1479 }
1480
1481 /*
1482 * First, test whether the goal block is free.
1483 */
1484 if (goal < le32_to_cpu(es->s_first_data_block) ||
1485 goal >= ext4_blocks_count(es))
1486 goal = le32_to_cpu(es->s_first_data_block);
1487 ext4_get_group_no_and_offset(sb, goal, &group_no, &grp_target_blk);
1488 goal_group = group_no;
1489retry_alloc:
1490 gdp = ext4_get_group_desc(sb, group_no, &gdp_bh);
1491 if (!gdp)
1492 goto io_error;
1493
1494 free_blocks = le16_to_cpu(gdp->bg_free_blocks_count);
1495 /*
1496 * if there is not enough free blocks to make a new resevation
1497 * turn off reservation for this allocation
1498 */
1499 if (my_rsv && (free_blocks < windowsz)
1500 && (rsv_is_empty(&my_rsv->rsv_window)))
1501 my_rsv = NULL;
1502
1503 if (free_blocks > 0) {
1504 bitmap_bh = read_block_bitmap(sb, group_no);
1505 if (!bitmap_bh)
1506 goto io_error;
1507 grp_alloc_blk = ext4_try_to_allocate_with_rsv(sb, handle,
1508 group_no, bitmap_bh, grp_target_blk,
1509 my_rsv, &num, &fatal);
1510 if (fatal)
1511 goto out;
1512 if (grp_alloc_blk >= 0)
1513 goto allocated;
1514 }
1515
1516 ngroups = EXT4_SB(sb)->s_groups_count;
1517 smp_rmb();
1518
1519 /*
1520 * Now search the rest of the groups. We assume that
1521 * i and gdp correctly point to the last group visited.
1522 */
1523 for (bgi = 0; bgi < ngroups; bgi++) {
1524 group_no++;
1525 if (group_no >= ngroups)
1526 group_no = 0;
1527 gdp = ext4_get_group_desc(sb, group_no, &gdp_bh);
1528 if (!gdp) {
1529 *errp = -EIO;
1530 goto out;
1531 }
1532 free_blocks = le16_to_cpu(gdp->bg_free_blocks_count);
1533 /*
1534 * skip this group if the number of
1535 * free blocks is less than half of the reservation
1536 * window size.
1537 */
1538 if (free_blocks <= (windowsz/2))
1539 continue;
1540
1541 brelse(bitmap_bh);
1542 bitmap_bh = read_block_bitmap(sb, group_no);
1543 if (!bitmap_bh)
1544 goto io_error;
1545 /*
1546 * try to allocate block(s) from this group, without a goal(-1).
1547 */
1548 grp_alloc_blk = ext4_try_to_allocate_with_rsv(sb, handle,
1549 group_no, bitmap_bh, -1, my_rsv,
1550 &num, &fatal);
1551 if (fatal)
1552 goto out;
1553 if (grp_alloc_blk >= 0)
1554 goto allocated;
1555 }
1556 /*
1557 * We may end up a bogus ealier ENOSPC error due to
1558 * filesystem is "full" of reservations, but
1559 * there maybe indeed free blocks avaliable on disk
1560 * In this case, we just forget about the reservations
1561 * just do block allocation as without reservations.
1562 */
1563 if (my_rsv) {
1564 my_rsv = NULL;
1565 group_no = goal_group;
1566 goto retry_alloc;
1567 }
1568 /* No space left on the device */
1569 *errp = -ENOSPC;
1570 goto out;
1571
1572allocated:
1573
1574 ext4_debug("using block group %d(%d)\n",
1575 group_no, gdp->bg_free_blocks_count);
1576
1577 BUFFER_TRACE(gdp_bh, "get_write_access");
1578 fatal = ext4_journal_get_write_access(handle, gdp_bh);
1579 if (fatal)
1580 goto out;
1581
1582 ret_block = grp_alloc_blk + ext4_group_first_block_no(sb, group_no);
1583
1584 if (in_range(ext4_block_bitmap(sb, gdp), ret_block, num) ||
1585 in_range(ext4_block_bitmap(sb, gdp), ret_block, num) ||
1586 in_range(ret_block, ext4_inode_table(sb, gdp),
1587 EXT4_SB(sb)->s_itb_per_group) ||
1588 in_range(ret_block + num - 1, ext4_inode_table(sb, gdp),
1589 EXT4_SB(sb)->s_itb_per_group))
1590 ext4_error(sb, "ext4_new_block",
1591 "Allocating block in system zone - "
1592 "blocks from %llu, length %lu",
1593 ret_block, num);
1594
1595 performed_allocation = 1;
1596
1597#ifdef CONFIG_JBD_DEBUG
1598 {
1599 struct buffer_head *debug_bh;
1600
1601 /* Record bitmap buffer state in the newly allocated block */
1602 debug_bh = sb_find_get_block(sb, ret_block);
1603 if (debug_bh) {
1604 BUFFER_TRACE(debug_bh, "state when allocated");
1605 BUFFER_TRACE2(debug_bh, bitmap_bh, "bitmap state");
1606 brelse(debug_bh);
1607 }
1608 }
1609 jbd_lock_bh_state(bitmap_bh);
1610 spin_lock(sb_bgl_lock(sbi, group_no));
1611 if (buffer_jbd(bitmap_bh) && bh2jh(bitmap_bh)->b_committed_data) {
1612 int i;
1613
1614 for (i = 0; i < num; i++) {
1615 if (ext4_test_bit(grp_alloc_blk+i,
1616 bh2jh(bitmap_bh)->b_committed_data)) {
1617 printk("%s: block was unexpectedly set in "
1618 "b_committed_data\n", __FUNCTION__);
1619 }
1620 }
1621 }
1622 ext4_debug("found bit %d\n", grp_alloc_blk);
1623 spin_unlock(sb_bgl_lock(sbi, group_no));
1624 jbd_unlock_bh_state(bitmap_bh);
1625#endif
1626
1627 if (ret_block + num - 1 >= ext4_blocks_count(es)) {
1628 ext4_error(sb, "ext4_new_block",
1629 "block(%llu) >= blocks count(%llu) - "
1630 "block_group = %lu, es == %p ", ret_block,
1631 ext4_blocks_count(es), group_no, es);
1632 goto out;
1633 }
1634
1635 /*
1636 * It is up to the caller to add the new buffer to a journal
1637 * list of some description. We don't know in advance whether
1638 * the caller wants to use it as metadata or data.
1639 */
1640 ext4_debug("allocating block %lu. Goal hits %d of %d.\n",
1641 ret_block, goal_hits, goal_attempts);
1642
1643 spin_lock(sb_bgl_lock(sbi, group_no));
1644 gdp->bg_free_blocks_count =
1645 cpu_to_le16(le16_to_cpu(gdp->bg_free_blocks_count)-num);
1646 spin_unlock(sb_bgl_lock(sbi, group_no));
1647 percpu_counter_mod(&sbi->s_freeblocks_counter, -num);
1648
1649 BUFFER_TRACE(gdp_bh, "journal_dirty_metadata for group descriptor");
1650 err = ext4_journal_dirty_metadata(handle, gdp_bh);
1651 if (!fatal)
1652 fatal = err;
1653
1654 sb->s_dirt = 1;
1655 if (fatal)
1656 goto out;
1657
1658 *errp = 0;
1659 brelse(bitmap_bh);
1660 DQUOT_FREE_BLOCK(inode, *count-num);
1661 *count = num;
1662 return ret_block;
1663
1664io_error:
1665 *errp = -EIO;
1666out:
1667 if (fatal) {
1668 *errp = fatal;
1669 ext4_std_error(sb, fatal);
1670 }
1671 /*
1672 * Undo the block allocation
1673 */
1674 if (!performed_allocation)
1675 DQUOT_FREE_BLOCK(inode, *count);
1676 brelse(bitmap_bh);
1677 return 0;
1678}
1679
1680ext4_fsblk_t ext4_new_block(handle_t *handle, struct inode *inode,
1681 ext4_fsblk_t goal, int *errp)
1682{
1683 unsigned long count = 1;
1684
1685 return ext4_new_blocks(handle, inode, goal, &count, errp);
1686}
1687
1688/**
1689 * ext4_count_free_blocks() -- count filesystem free blocks
1690 * @sb: superblock
1691 *
1692 * Adds up the number of free blocks from each block group.
1693 */
1694ext4_fsblk_t ext4_count_free_blocks(struct super_block *sb)
1695{
1696 ext4_fsblk_t desc_count;
1697 struct ext4_group_desc *gdp;
1698 int i;
1699 unsigned long ngroups = EXT4_SB(sb)->s_groups_count;
1700#ifdef EXT4FS_DEBUG
1701 struct ext4_super_block *es;
1702 ext4_fsblk_t bitmap_count;
1703 unsigned long x;
1704 struct buffer_head *bitmap_bh = NULL;
1705
1706 es = EXT4_SB(sb)->s_es;
1707 desc_count = 0;
1708 bitmap_count = 0;
1709 gdp = NULL;
1710
1711 smp_rmb();
1712 for (i = 0; i < ngroups; i++) {
1713 gdp = ext4_get_group_desc(sb, i, NULL);
1714 if (!gdp)
1715 continue;
1716 desc_count += le16_to_cpu(gdp->bg_free_blocks_count);
1717 brelse(bitmap_bh);
1718 bitmap_bh = read_block_bitmap(sb, i);
1719 if (bitmap_bh == NULL)
1720 continue;
1721
1722 x = ext4_count_free(bitmap_bh, sb->s_blocksize);
1723 printk("group %d: stored = %d, counted = %lu\n",
1724 i, le16_to_cpu(gdp->bg_free_blocks_count), x);
1725 bitmap_count += x;
1726 }
1727 brelse(bitmap_bh);
1728 printk("ext4_count_free_blocks: stored = %llu"
1729 ", computed = %llu, %llu\n",
1730 EXT4_FREE_BLOCKS_COUNT(es),
1731 desc_count, bitmap_count);
1732 return bitmap_count;
1733#else
1734 desc_count = 0;
1735 smp_rmb();
1736 for (i = 0; i < ngroups; i++) {
1737 gdp = ext4_get_group_desc(sb, i, NULL);
1738 if (!gdp)
1739 continue;
1740 desc_count += le16_to_cpu(gdp->bg_free_blocks_count);
1741 }
1742
1743 return desc_count;
1744#endif
1745}
1746
1747static inline int
1748block_in_use(ext4_fsblk_t block, struct super_block *sb, unsigned char *map)
1749{
1750 ext4_grpblk_t offset;
1751
1752 ext4_get_group_no_and_offset(sb, block, NULL, &offset);
1753 return ext4_test_bit (offset, map);
1754}
1755
1756static inline int test_root(int a, int b)
1757{
1758 int num = b;
1759
1760 while (a > num)
1761 num *= b;
1762 return num == a;
1763}
1764
1765static int ext4_group_sparse(int group)
1766{
1767 if (group <= 1)
1768 return 1;
1769 if (!(group & 1))
1770 return 0;
1771 return (test_root(group, 7) || test_root(group, 5) ||
1772 test_root(group, 3));
1773}
1774
1775/**
1776 * ext4_bg_has_super - number of blocks used by the superblock in group
1777 * @sb: superblock for filesystem
1778 * @group: group number to check
1779 *
1780 * Return the number of blocks used by the superblock (primary or backup)
1781 * in this group. Currently this will be only 0 or 1.
1782 */
1783int ext4_bg_has_super(struct super_block *sb, int group)
1784{
1785 if (EXT4_HAS_RO_COMPAT_FEATURE(sb,
1786 EXT4_FEATURE_RO_COMPAT_SPARSE_SUPER) &&
1787 !ext4_group_sparse(group))
1788 return 0;
1789 return 1;
1790}
1791
1792static unsigned long ext4_bg_num_gdb_meta(struct super_block *sb, int group)
1793{
1794 unsigned long metagroup = group / EXT4_DESC_PER_BLOCK(sb);
1795 unsigned long first = metagroup * EXT4_DESC_PER_BLOCK(sb);
1796 unsigned long last = first + EXT4_DESC_PER_BLOCK(sb) - 1;
1797
1798 if (group == first || group == first + 1 || group == last)
1799 return 1;
1800 return 0;
1801}
1802
1803static unsigned long ext4_bg_num_gdb_nometa(struct super_block *sb, int group)
1804{
1805 if (EXT4_HAS_RO_COMPAT_FEATURE(sb,
1806 EXT4_FEATURE_RO_COMPAT_SPARSE_SUPER) &&
1807 !ext4_group_sparse(group))
1808 return 0;
1809 return EXT4_SB(sb)->s_gdb_count;
1810}
1811
1812/**
1813 * ext4_bg_num_gdb - number of blocks used by the group table in group
1814 * @sb: superblock for filesystem
1815 * @group: group number to check
1816 *
1817 * Return the number of blocks used by the group descriptor table
1818 * (primary or backup) in this group. In the future there may be a
1819 * different number of descriptor blocks in each group.
1820 */
1821unsigned long ext4_bg_num_gdb(struct super_block *sb, int group)
1822{
1823 unsigned long first_meta_bg =
1824 le32_to_cpu(EXT4_SB(sb)->s_es->s_first_meta_bg);
1825 unsigned long metagroup = group / EXT4_DESC_PER_BLOCK(sb);
1826
1827 if (!EXT4_HAS_INCOMPAT_FEATURE(sb,EXT4_FEATURE_INCOMPAT_META_BG) ||
1828 metagroup < first_meta_bg)
1829 return ext4_bg_num_gdb_nometa(sb,group);
1830
1831 return ext4_bg_num_gdb_meta(sb,group);
1832
1833}
generated by cgit v1.2.2 (git 2.25.0) at 2025-09-12 14:04:11 -0400