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2 * This file is part of UBIFS.
4 * Copyright (C) 2006-2008 Nokia Corporation.
6 * This program is free software; you can redistribute it and/or modify it
7 * under the terms of the GNU General Public License version 2 as published by
8 * the Free Software Foundation.
10 * This program is distributed in the hope that it will be useful, but WITHOUT
11 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
12 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
15 * You should have received a copy of the GNU General Public License along with
16 * this program; if not, write to the Free Software Foundation, Inc., 51
17 * Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
19 * Authors: Adrian Hunter
20 * Artem Bityutskiy (Битюцкий Артём)
24 * This file implements garbage collection. The procedure for garbage collection
25 * is different depending on whether a LEB as an index LEB (contains index
26 * nodes) or not. For non-index LEBs, garbage collection finds a LEB which
27 * contains a lot of dirty space (obsolete nodes), and copies the non-obsolete
28 * nodes to the journal, at which point the garbage-collected LEB is free to be
29 * reused. For index LEBs, garbage collection marks the non-obsolete index nodes
30 * dirty in the TNC, and after the next commit, the garbage-collected LEB is
31 * to be reused. Garbage collection will cause the number of dirty index nodes
32 * to grow, however sufficient space is reserved for the index to ensure the
33 * commit will never run out of space.
35 * Notes about dead watermark. At current UBIFS implementation we assume that
36 * LEBs which have less than @c->dead_wm bytes of free + dirty space are full
37 * and not worth garbage-collecting. The dead watermark is one min. I/O unit
38 * size, or min. UBIFS node size, depending on what is greater. Indeed, UBIFS
39 * Garbage Collector has to synchronize the GC head's write buffer before
40 * returning, so this is about wasting one min. I/O unit. However, UBIFS GC can
41 * actually reclaim even very small pieces of dirty space by garbage collecting
42 * enough dirty LEBs, but we do not bother doing this at this implementation.
44 * Notes about dark watermark. The results of GC work depends on how big are
45 * the UBIFS nodes GC deals with. Large nodes make GC waste more space. Indeed,
46 * if GC move data from LEB A to LEB B and nodes in LEB A are large, GC would
47 * have to waste large pieces of free space at the end of LEB B, because nodes
48 * from LEB A would not fit. And the worst situation is when all nodes are of
49 * maximum size. So dark watermark is the amount of free + dirty space in LEB
50 * which are guaranteed to be reclaimable. If LEB has less space, the GC might
51 * be unable to reclaim it. So, LEBs with free + dirty greater than dark
52 * watermark are "good" LEBs from GC's point of few. The other LEBs are not so
53 * good, and GC takes extra care when moving them.
56 #include <linux/slab.h>
57 #include <linux/pagemap.h>
58 #include <linux/list_sort.h>
62 * GC may need to move more than one LEB to make progress. The below constants
63 * define "soft" and "hard" limits on the number of LEBs the garbage collector
66 #define SOFT_LEBS_LIMIT 4
67 #define HARD_LEBS_LIMIT 32
70 * switch_gc_head - switch the garbage collection journal head.
71 * @c: UBIFS file-system description object
72 * @buf: buffer to write
73 * @len: length of the buffer to write
74 * @lnum: LEB number written is returned here
75 * @offs: offset written is returned here
77 * This function switch the GC head to the next LEB which is reserved in
78 * @c->gc_lnum. Returns %0 in case of success, %-EAGAIN if commit is required,
79 * and other negative error code in case of failures.
81 static int switch_gc_head(struct ubifs_info
*c
)
83 int err
, gc_lnum
= c
->gc_lnum
;
84 struct ubifs_wbuf
*wbuf
= &c
->jheads
[GCHD
].wbuf
;
86 ubifs_assert(gc_lnum
!= -1);
87 dbg_gc("switch GC head from LEB %d:%d to LEB %d (waste %d bytes)",
88 wbuf
->lnum
, wbuf
->offs
+ wbuf
->used
, gc_lnum
,
89 c
->leb_size
- wbuf
->offs
- wbuf
->used
);
91 err
= ubifs_wbuf_sync_nolock(wbuf
);
96 * The GC write-buffer was synchronized, we may safely unmap
99 err
= ubifs_leb_unmap(c
, gc_lnum
);
103 err
= ubifs_add_bud_to_log(c
, GCHD
, gc_lnum
, 0);
108 err
= ubifs_wbuf_seek_nolock(wbuf
, gc_lnum
, 0, UBI_LONGTERM
);
113 * data_nodes_cmp - compare 2 data nodes.
114 * @priv: UBIFS file-system description object
115 * @a: first data node
116 * @a: second data node
118 * This function compares data nodes @a and @b. Returns %1 if @a has greater
119 * inode or block number, and %-1 otherwise.
121 int data_nodes_cmp(void *priv
, struct list_head
*a
, struct list_head
*b
)
124 struct ubifs_info
*c
= priv
;
125 struct ubifs_scan_node
*sa
, *sb
;
131 sa
= list_entry(a
, struct ubifs_scan_node
, list
);
132 sb
= list_entry(b
, struct ubifs_scan_node
, list
);
134 ubifs_assert(key_type(c
, &sa
->key
) == UBIFS_DATA_KEY
);
135 ubifs_assert(key_type(c
, &sb
->key
) == UBIFS_DATA_KEY
);
136 ubifs_assert(sa
->type
== UBIFS_DATA_NODE
);
137 ubifs_assert(sb
->type
== UBIFS_DATA_NODE
);
139 inuma
= key_inum(c
, &sa
->key
);
140 inumb
= key_inum(c
, &sb
->key
);
142 if (inuma
== inumb
) {
143 unsigned int blka
= key_block(c
, &sa
->key
);
144 unsigned int blkb
= key_block(c
, &sb
->key
);
148 } else if (inuma
<= inumb
)
155 * nondata_nodes_cmp - compare 2 non-data nodes.
156 * @priv: UBIFS file-system description object
160 * This function compares nodes @a and @b. It makes sure that inode nodes go
161 * first and sorted by length in descending order. Directory entry nodes go
162 * after inode nodes and are sorted in ascending hash valuer order.
164 int nondata_nodes_cmp(void *priv
, struct list_head
*a
, struct list_head
*b
)
167 struct ubifs_info
*c
= priv
;
168 struct ubifs_scan_node
*sa
, *sb
;
174 sa
= list_entry(a
, struct ubifs_scan_node
, list
);
175 sb
= list_entry(b
, struct ubifs_scan_node
, list
);
177 ubifs_assert(key_type(c
, &sa
->key
) != UBIFS_DATA_KEY
&&
178 key_type(c
, &sb
->key
) != UBIFS_DATA_KEY
);
179 ubifs_assert(sa
->type
!= UBIFS_DATA_NODE
&&
180 sb
->type
!= UBIFS_DATA_NODE
);
182 /* Inodes go before directory entries */
183 if (sa
->type
== UBIFS_INO_NODE
) {
184 if (sb
->type
== UBIFS_INO_NODE
)
185 return sb
->len
- sa
->len
;
188 if (sb
->type
== UBIFS_INO_NODE
)
191 ubifs_assert(key_type(c
, &sa
->key
) == UBIFS_DENT_KEY
||
192 key_type(c
, &sa
->key
) == UBIFS_XENT_KEY
);
193 ubifs_assert(key_type(c
, &sb
->key
) == UBIFS_DENT_KEY
||
194 key_type(c
, &sb
->key
) == UBIFS_XENT_KEY
);
195 ubifs_assert(sa
->type
== UBIFS_DENT_NODE
||
196 sa
->type
== UBIFS_XENT_NODE
);
197 ubifs_assert(sb
->type
== UBIFS_DENT_NODE
||
198 sb
->type
== UBIFS_XENT_NODE
);
200 inuma
= key_inum(c
, &sa
->key
);
201 inumb
= key_inum(c
, &sb
->key
);
203 if (inuma
== inumb
) {
204 uint32_t hasha
= key_hash(c
, &sa
->key
);
205 uint32_t hashb
= key_hash(c
, &sb
->key
);
209 } else if (inuma
<= inumb
)
216 * sort_nodes - sort nodes for GC.
217 * @c: UBIFS file-system description object
218 * @sleb: describes nodes to sort and contains the result on exit
219 * @nondata: contains non-data nodes on exit
220 * @min: minimum node size is returned here
222 * This function sorts the list of inodes to garbage collect. First of all, it
223 * kills obsolete nodes and separates data and non-data nodes to the
224 * @sleb->nodes and @nondata lists correspondingly.
226 * Data nodes are then sorted in block number order - this is important for
227 * bulk-read; data nodes with lower inode number go before data nodes with
228 * higher inode number, and data nodes with lower block number go before data
229 * nodes with higher block number;
231 * Non-data nodes are sorted as follows.
232 * o First go inode nodes - they are sorted in descending length order.
233 * o Then go directory entry nodes - they are sorted in hash order, which
234 * should supposedly optimize 'readdir()'. Direntry nodes with lower parent
235 * inode number go before direntry nodes with higher parent inode number,
236 * and direntry nodes with lower name hash values go before direntry nodes
237 * with higher name hash values.
239 * This function returns zero in case of success and a negative error code in
242 static int sort_nodes(struct ubifs_info
*c
, struct ubifs_scan_leb
*sleb
,
243 struct list_head
*nondata
, int *min
)
246 struct ubifs_scan_node
*snod
, *tmp
;
250 /* Separate data nodes and non-data nodes */
251 list_for_each_entry_safe(snod
, tmp
, &sleb
->nodes
, list
) {
252 ubifs_assert(snod
->type
== UBIFS_INO_NODE
||
253 snod
->type
== UBIFS_DATA_NODE
||
254 snod
->type
== UBIFS_DENT_NODE
||
255 snod
->type
== UBIFS_XENT_NODE
||
256 snod
->type
== UBIFS_TRUN_NODE
);
258 if (snod
->type
!= UBIFS_INO_NODE
&&
259 snod
->type
!= UBIFS_DATA_NODE
&&
260 snod
->type
!= UBIFS_DENT_NODE
&&
261 snod
->type
!= UBIFS_XENT_NODE
) {
262 /* Probably truncation node, zap it */
263 list_del(&snod
->list
);
268 ubifs_assert(key_type(c
, &snod
->key
) == UBIFS_DATA_KEY
||
269 key_type(c
, &snod
->key
) == UBIFS_INO_KEY
||
270 key_type(c
, &snod
->key
) == UBIFS_DENT_KEY
||
271 key_type(c
, &snod
->key
) == UBIFS_XENT_KEY
);
273 err
= ubifs_tnc_has_node(c
, &snod
->key
, 0, sleb
->lnum
,
279 /* The node is obsolete, remove it from the list */
280 list_del(&snod
->list
);
285 if (snod
->len
< *min
)
288 if (key_type(c
, &snod
->key
) != UBIFS_DATA_KEY
)
289 list_move_tail(&snod
->list
, nondata
);
292 /* Sort data and non-data nodes */
293 list_sort(c
, &sleb
->nodes
, &data_nodes_cmp
);
294 list_sort(c
, nondata
, &nondata_nodes_cmp
);
296 err
= dbg_check_data_nodes_order(c
, &sleb
->nodes
);
299 err
= dbg_check_nondata_nodes_order(c
, nondata
);
306 * move_node - move a node.
307 * @c: UBIFS file-system description object
308 * @sleb: describes the LEB to move nodes from
309 * @snod: the mode to move
310 * @wbuf: write-buffer to move node to
312 * This function moves node @snod to @wbuf, changes TNC correspondingly, and
313 * destroys @snod. Returns zero in case of success and a negative error code in
316 static int move_node(struct ubifs_info
*c
, struct ubifs_scan_leb
*sleb
,
317 struct ubifs_scan_node
*snod
, struct ubifs_wbuf
*wbuf
)
319 int err
, new_lnum
= wbuf
->lnum
, new_offs
= wbuf
->offs
+ wbuf
->used
;
322 err
= ubifs_wbuf_write_nolock(wbuf
, snod
->node
, snod
->len
);
326 err
= ubifs_tnc_replace(c
, &snod
->key
, sleb
->lnum
,
327 snod
->offs
, new_lnum
, new_offs
,
329 list_del(&snod
->list
);
335 * move_nodes - move nodes.
336 * @c: UBIFS file-system description object
337 * @sleb: describes the LEB to move nodes from
339 * This function moves valid nodes from data LEB described by @sleb to the GC
340 * journal head. This function returns zero in case of success, %-EAGAIN if
341 * commit is required, and other negative error codes in case of other
344 static int move_nodes(struct ubifs_info
*c
, struct ubifs_scan_leb
*sleb
)
348 struct ubifs_wbuf
*wbuf
= &c
->jheads
[GCHD
].wbuf
;
350 if (wbuf
->lnum
== -1) {
352 * The GC journal head is not set, because it is the first GC
353 * invocation since mount.
355 err
= switch_gc_head(c
);
360 err
= sort_nodes(c
, sleb
, &nondata
, &min
);
364 /* Write nodes to their new location. Use the first-fit strategy */
367 struct ubifs_scan_node
*snod
, *tmp
;
369 /* Move data nodes */
370 list_for_each_entry_safe(snod
, tmp
, &sleb
->nodes
, list
) {
371 avail
= c
->leb_size
- wbuf
->offs
- wbuf
->used
;
372 if (snod
->len
> avail
)
374 * Do not skip data nodes in order to optimize
379 err
= move_node(c
, sleb
, snod
, wbuf
);
384 /* Move non-data nodes */
385 list_for_each_entry_safe(snod
, tmp
, &nondata
, list
) {
386 avail
= c
->leb_size
- wbuf
->offs
- wbuf
->used
;
390 if (snod
->len
> avail
) {
392 * Keep going only if this is an inode with
393 * some data. Otherwise stop and switch the GC
394 * head. IOW, we assume that data-less inode
395 * nodes and direntry nodes are roughly of the
398 if (key_type(c
, &snod
->key
) == UBIFS_DENT_KEY
||
399 snod
->len
== UBIFS_INO_NODE_SZ
)
404 err
= move_node(c
, sleb
, snod
, wbuf
);
409 if (list_empty(&sleb
->nodes
) && list_empty(&nondata
))
413 * Waste the rest of the space in the LEB and switch to the
416 err
= switch_gc_head(c
);
424 list_splice_tail(&nondata
, &sleb
->nodes
);
429 * gc_sync_wbufs - sync write-buffers for GC.
430 * @c: UBIFS file-system description object
432 * We must guarantee that obsoleting nodes are on flash. Unfortunately they may
433 * be in a write-buffer instead. That is, a node could be written to a
434 * write-buffer, obsoleting another node in a LEB that is GC'd. If that LEB is
435 * erased before the write-buffer is sync'd and then there is an unclean
436 * unmount, then an existing node is lost. To avoid this, we sync all
439 * This function returns %0 on success or a negative error code on failure.
441 static int gc_sync_wbufs(struct ubifs_info
*c
)
445 for (i
= 0; i
< c
->jhead_cnt
; i
++) {
448 err
= ubifs_wbuf_sync(&c
->jheads
[i
].wbuf
);
456 * ubifs_garbage_collect_leb - garbage-collect a logical eraseblock.
457 * @c: UBIFS file-system description object
458 * @lp: describes the LEB to garbage collect
460 * This function garbage-collects an LEB and returns one of the @LEB_FREED,
461 * @LEB_RETAINED, etc positive codes in case of success, %-EAGAIN if commit is
462 * required, and other negative error codes in case of failures.
464 int ubifs_garbage_collect_leb(struct ubifs_info
*c
, struct ubifs_lprops
*lp
)
466 struct ubifs_scan_leb
*sleb
;
467 struct ubifs_scan_node
*snod
;
468 struct ubifs_wbuf
*wbuf
= &c
->jheads
[GCHD
].wbuf
;
469 int err
= 0, lnum
= lp
->lnum
;
471 ubifs_assert(c
->gc_lnum
!= -1 || wbuf
->offs
+ wbuf
->used
== 0 ||
473 ubifs_assert(c
->gc_lnum
!= lnum
);
474 ubifs_assert(wbuf
->lnum
!= lnum
);
477 * We scan the entire LEB even though we only really need to scan up to
478 * (c->leb_size - lp->free).
480 sleb
= ubifs_scan(c
, lnum
, 0, c
->sbuf
, 0);
482 return PTR_ERR(sleb
);
484 ubifs_assert(!list_empty(&sleb
->nodes
));
485 snod
= list_entry(sleb
->nodes
.next
, struct ubifs_scan_node
, list
);
487 if (snod
->type
== UBIFS_IDX_NODE
) {
488 struct ubifs_gced_idx_leb
*idx_gc
;
490 dbg_gc("indexing LEB %d (free %d, dirty %d)",
491 lnum
, lp
->free
, lp
->dirty
);
492 list_for_each_entry(snod
, &sleb
->nodes
, list
) {
493 struct ubifs_idx_node
*idx
= snod
->node
;
494 int level
= le16_to_cpu(idx
->level
);
496 ubifs_assert(snod
->type
== UBIFS_IDX_NODE
);
497 key_read(c
, ubifs_idx_key(c
, idx
), &snod
->key
);
498 err
= ubifs_dirty_idx_node(c
, &snod
->key
, level
, lnum
,
504 idx_gc
= kmalloc(sizeof(struct ubifs_gced_idx_leb
), GFP_NOFS
);
512 list_add(&idx_gc
->list
, &c
->idx_gc
);
515 * Don't release the LEB until after the next commit, because
516 * it may contain data which is needed for recovery. So
517 * although we freed this LEB, it will become usable only after
520 err
= ubifs_change_one_lp(c
, lnum
, c
->leb_size
, 0, 0,
526 dbg_gc("data LEB %d (free %d, dirty %d)",
527 lnum
, lp
->free
, lp
->dirty
);
529 err
= move_nodes(c
, sleb
);
533 err
= gc_sync_wbufs(c
);
537 err
= ubifs_change_one_lp(c
, lnum
, c
->leb_size
, 0, 0, 0, 0);
541 /* Allow for races with TNC */
547 if (c
->gc_lnum
== -1) {
551 err
= ubifs_wbuf_sync_nolock(wbuf
);
555 err
= ubifs_leb_unmap(c
, lnum
);
564 ubifs_scan_destroy(sleb
);
568 /* We may have moved at least some nodes so allow for races with TNC */
577 * ubifs_garbage_collect - UBIFS garbage collector.
578 * @c: UBIFS file-system description object
579 * @anyway: do GC even if there are free LEBs
581 * This function does out-of-place garbage collection. The return codes are:
582 * o positive LEB number if the LEB has been freed and may be used;
583 * o %-EAGAIN if the caller has to run commit;
584 * o %-ENOSPC if GC failed to make any progress;
585 * o other negative error codes in case of other errors.
587 * Garbage collector writes data to the journal when GC'ing data LEBs, and just
588 * marking indexing nodes dirty when GC'ing indexing LEBs. Thus, at some point
589 * commit may be required. But commit cannot be run from inside GC, because the
590 * caller might be holding the commit lock, so %-EAGAIN is returned instead;
591 * And this error code means that the caller has to run commit, and re-run GC
592 * if there is still no free space.
594 * There are many reasons why this function may return %-EAGAIN:
595 * o the log is full and there is no space to write an LEB reference for
597 * o the journal is too large and exceeds size limitations;
598 * o GC moved indexing LEBs, but they can be used only after the commit;
599 * o the shrinker fails to find clean znodes to free and requests the commit;
602 * Note, if the file-system is close to be full, this function may return
603 * %-EAGAIN infinitely, so the caller has to limit amount of re-invocations of
604 * the function. E.g., this happens if the limits on the journal size are too
605 * tough and GC writes too much to the journal before an LEB is freed. This
606 * might also mean that the journal is too large, and the TNC becomes to big,
607 * so that the shrinker is constantly called, finds not clean znodes to free,
608 * and requests commit. Well, this may also happen if the journal is all right,
609 * but another kernel process consumes too much memory. Anyway, infinite
610 * %-EAGAIN may happen, but in some extreme/misconfiguration cases.
612 int ubifs_garbage_collect(struct ubifs_info
*c
, int anyway
)
614 int i
, err
, ret
, min_space
= c
->dead_wm
;
615 struct ubifs_lprops lp
;
616 struct ubifs_wbuf
*wbuf
= &c
->jheads
[GCHD
].wbuf
;
618 ubifs_assert_cmt_locked(c
);
619 ubifs_assert(!c
->ro_media
&& !c
->ro_mount
);
621 if (ubifs_gc_should_commit(c
))
624 mutex_lock_nested(&wbuf
->io_mutex
, wbuf
->jhead
);
631 /* We expect the write-buffer to be empty on entry */
632 ubifs_assert(!wbuf
->used
);
635 int space_before
= c
->leb_size
- wbuf
->offs
- wbuf
->used
;
640 /* Give the commit an opportunity to run */
641 if (ubifs_gc_should_commit(c
)) {
646 if (i
> SOFT_LEBS_LIMIT
&& !list_empty(&c
->idx_gc
)) {
648 * We've done enough iterations. Indexing LEBs were
649 * moved and will be available after the commit.
651 dbg_gc("soft limit, some index LEBs GC'ed, -EAGAIN");
652 ubifs_commit_required(c
);
657 if (i
> HARD_LEBS_LIMIT
) {
659 * We've moved too many LEBs and have not made
662 dbg_gc("hard limit, -ENOSPC");
668 * Empty and freeable LEBs can turn up while we waited for
669 * the wbuf lock, or while we have been running GC. In that
670 * case, we should just return one of those instead of
671 * continuing to GC dirty LEBs. Hence we request
672 * 'ubifs_find_dirty_leb()' to return an empty LEB if it can.
674 ret
= ubifs_find_dirty_leb(c
, &lp
, min_space
, anyway
? 0 : 1);
677 dbg_gc("no more dirty LEBs");
681 dbg_gc("found LEB %d: free %d, dirty %d, sum %d "
682 "(min. space %d)", lp
.lnum
, lp
.free
, lp
.dirty
,
683 lp
.free
+ lp
.dirty
, min_space
);
685 if (lp
.free
+ lp
.dirty
== c
->leb_size
) {
686 /* An empty LEB was returned */
687 dbg_gc("LEB %d is free, return it", lp
.lnum
);
689 * ubifs_find_dirty_leb() doesn't return freeable index
692 ubifs_assert(!(lp
.flags
& LPROPS_INDEX
));
693 if (lp
.free
!= c
->leb_size
) {
695 * Write buffers must be sync'd before
696 * unmapping freeable LEBs, because one of them
697 * may contain data which obsoletes something
700 ret
= gc_sync_wbufs(c
);
703 ret
= ubifs_change_one_lp(c
, lp
.lnum
,
704 c
->leb_size
, 0, 0, 0,
709 ret
= ubifs_leb_unmap(c
, lp
.lnum
);
716 space_before
= c
->leb_size
- wbuf
->offs
- wbuf
->used
;
717 if (wbuf
->lnum
== -1)
720 ret
= ubifs_garbage_collect_leb(c
, &lp
);
722 if (ret
== -EAGAIN
) {
724 * This is not error, so we have to return the
725 * LEB to lprops. But if 'ubifs_return_leb()'
726 * fails, its failure code is propagated to the
727 * caller instead of the original '-EAGAIN'.
729 err
= ubifs_return_leb(c
, lp
.lnum
);
737 if (ret
== LEB_FREED
) {
738 /* An LEB has been freed and is ready for use */
739 dbg_gc("LEB %d freed, return", lp
.lnum
);
744 if (ret
== LEB_FREED_IDX
) {
746 * This was an indexing LEB and it cannot be
747 * immediately used. And instead of requesting the
748 * commit straight away, we try to garbage collect some
751 dbg_gc("indexing LEB %d freed, continue", lp
.lnum
);
755 ubifs_assert(ret
== LEB_RETAINED
);
756 space_after
= c
->leb_size
- wbuf
->offs
- wbuf
->used
;
757 dbg_gc("LEB %d retained, freed %d bytes", lp
.lnum
,
758 space_after
- space_before
);
760 if (space_after
> space_before
) {
761 /* GC makes progress, keep working */
763 if (min_space
< c
->dead_wm
)
764 min_space
= c
->dead_wm
;
768 dbg_gc("did not make progress");
771 * GC moved an LEB bud have not done any progress. This means
772 * that the previous GC head LEB contained too few free space
773 * and the LEB which was GC'ed contained only large nodes which
774 * did not fit that space.
776 * We can do 2 things:
777 * 1. pick another LEB in a hope it'll contain a small node
778 * which will fit the space we have at the end of current GC
779 * head LEB, but there is no guarantee, so we try this out
780 * unless we have already been working for too long;
781 * 2. request an LEB with more dirty space, which will force
782 * 'ubifs_find_dirty_leb()' to start scanning the lprops
783 * table, instead of just picking one from the heap
784 * (previously it already picked the dirtiest LEB).
786 if (i
< SOFT_LEBS_LIMIT
) {
792 if (min_space
> c
->dark_wm
)
793 min_space
= c
->dark_wm
;
794 dbg_gc("set min. space to %d", min_space
);
797 if (ret
== -ENOSPC
&& !list_empty(&c
->idx_gc
)) {
798 dbg_gc("no space, some index LEBs GC'ed, -EAGAIN");
799 ubifs_commit_required(c
);
803 err
= ubifs_wbuf_sync_nolock(wbuf
);
805 err
= ubifs_leb_unmap(c
, c
->gc_lnum
);
811 mutex_unlock(&wbuf
->io_mutex
);
815 ubifs_assert(ret
< 0);
816 ubifs_assert(ret
!= -ENOSPC
&& ret
!= -EAGAIN
);
817 ubifs_wbuf_sync_nolock(wbuf
);
818 ubifs_ro_mode(c
, ret
);
819 mutex_unlock(&wbuf
->io_mutex
);
820 ubifs_return_leb(c
, lp
.lnum
);
825 * ubifs_gc_start_commit - garbage collection at start of commit.
826 * @c: UBIFS file-system description object
828 * If a LEB has only dirty and free space, then we may safely unmap it and make
829 * it free. Note, we cannot do this with indexing LEBs because dirty space may
830 * correspond index nodes that are required for recovery. In that case, the
831 * LEB cannot be unmapped until after the next commit.
833 * This function returns %0 upon success and a negative error code upon failure.
835 int ubifs_gc_start_commit(struct ubifs_info
*c
)
837 struct ubifs_gced_idx_leb
*idx_gc
;
838 const struct ubifs_lprops
*lp
;
844 * Unmap (non-index) freeable LEBs. Note that recovery requires that all
845 * wbufs are sync'd before this, which is done in 'do_commit()'.
848 lp
= ubifs_fast_find_freeable(c
);
855 ubifs_assert(!(lp
->flags
& LPROPS_TAKEN
));
856 ubifs_assert(!(lp
->flags
& LPROPS_INDEX
));
857 err
= ubifs_leb_unmap(c
, lp
->lnum
);
860 lp
= ubifs_change_lp(c
, lp
, c
->leb_size
, 0, lp
->flags
, 0);
865 ubifs_assert(!(lp
->flags
& LPROPS_TAKEN
));
866 ubifs_assert(!(lp
->flags
& LPROPS_INDEX
));
869 /* Mark GC'd index LEBs OK to unmap after this commit finishes */
870 list_for_each_entry(idx_gc
, &c
->idx_gc
, list
)
873 /* Record index freeable LEBs for unmapping after commit */
875 lp
= ubifs_fast_find_frdi_idx(c
);
882 idx_gc
= kmalloc(sizeof(struct ubifs_gced_idx_leb
), GFP_NOFS
);
887 ubifs_assert(!(lp
->flags
& LPROPS_TAKEN
));
888 ubifs_assert(lp
->flags
& LPROPS_INDEX
);
889 /* Don't release the LEB until after the next commit */
890 flags
= (lp
->flags
| LPROPS_TAKEN
) ^ LPROPS_INDEX
;
891 lp
= ubifs_change_lp(c
, lp
, c
->leb_size
, 0, flags
, 1);
897 ubifs_assert(lp
->flags
& LPROPS_TAKEN
);
898 ubifs_assert(!(lp
->flags
& LPROPS_INDEX
));
899 idx_gc
->lnum
= lp
->lnum
;
901 list_add(&idx_gc
->list
, &c
->idx_gc
);
904 ubifs_release_lprops(c
);
909 * ubifs_gc_end_commit - garbage collection at end of commit.
910 * @c: UBIFS file-system description object
912 * This function completes out-of-place garbage collection of index LEBs.
914 int ubifs_gc_end_commit(struct ubifs_info
*c
)
916 struct ubifs_gced_idx_leb
*idx_gc
, *tmp
;
917 struct ubifs_wbuf
*wbuf
;
920 wbuf
= &c
->jheads
[GCHD
].wbuf
;
921 mutex_lock_nested(&wbuf
->io_mutex
, wbuf
->jhead
);
922 list_for_each_entry_safe(idx_gc
, tmp
, &c
->idx_gc
, list
)
924 dbg_gc("LEB %d", idx_gc
->lnum
);
925 err
= ubifs_leb_unmap(c
, idx_gc
->lnum
);
928 err
= ubifs_change_one_lp(c
, idx_gc
->lnum
, LPROPS_NC
,
929 LPROPS_NC
, 0, LPROPS_TAKEN
, -1);
932 list_del(&idx_gc
->list
);
936 mutex_unlock(&wbuf
->io_mutex
);
941 * ubifs_destroy_idx_gc - destroy idx_gc list.
942 * @c: UBIFS file-system description object
944 * This function destroys the @c->idx_gc list. It is called when unmounting
945 * so locks are not needed. Returns zero in case of success and a negative
946 * error code in case of failure.
948 void ubifs_destroy_idx_gc(struct ubifs_info
*c
)
950 while (!list_empty(&c
->idx_gc
)) {
951 struct ubifs_gced_idx_leb
*idx_gc
;
953 idx_gc
= list_entry(c
->idx_gc
.next
, struct ubifs_gced_idx_leb
,
956 list_del(&idx_gc
->list
);
962 * ubifs_get_idx_gc_leb - get a LEB from GC'd index LEB list.
963 * @c: UBIFS file-system description object
965 * Called during start commit so locks are not needed.
967 int ubifs_get_idx_gc_leb(struct ubifs_info
*c
)
969 struct ubifs_gced_idx_leb
*idx_gc
;
972 if (list_empty(&c
->idx_gc
))
974 idx_gc
= list_entry(c
->idx_gc
.next
, struct ubifs_gced_idx_leb
, list
);
976 /* c->idx_gc_cnt is updated by the caller when lprops are updated */
977 list_del(&idx_gc
->list
);