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1001 lines
28 KiB
1001 lines
28 KiB
// SPDX-License-Identifier: GPL-2.0-only |
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/* |
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* This file is part of UBIFS. |
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* |
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* Copyright (C) 2006-2008 Nokia Corporation. |
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* |
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* Authors: Adrian Hunter |
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* Artem Bityutskiy (Битюцкий Артём) |
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*/ |
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|
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/* |
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* This file implements garbage collection. The procedure for garbage collection |
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* is different depending on whether a LEB as an index LEB (contains index |
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* nodes) or not. For non-index LEBs, garbage collection finds a LEB which |
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* contains a lot of dirty space (obsolete nodes), and copies the non-obsolete |
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* nodes to the journal, at which point the garbage-collected LEB is free to be |
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* reused. For index LEBs, garbage collection marks the non-obsolete index nodes |
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* dirty in the TNC, and after the next commit, the garbage-collected LEB is |
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* to be reused. Garbage collection will cause the number of dirty index nodes |
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* to grow, however sufficient space is reserved for the index to ensure the |
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* commit will never run out of space. |
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* |
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* Notes about dead watermark. At current UBIFS implementation we assume that |
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* LEBs which have less than @c->dead_wm bytes of free + dirty space are full |
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* and not worth garbage-collecting. The dead watermark is one min. I/O unit |
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* size, or min. UBIFS node size, depending on what is greater. Indeed, UBIFS |
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* Garbage Collector has to synchronize the GC head's write buffer before |
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* returning, so this is about wasting one min. I/O unit. However, UBIFS GC can |
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* actually reclaim even very small pieces of dirty space by garbage collecting |
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* enough dirty LEBs, but we do not bother doing this at this implementation. |
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* |
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* Notes about dark watermark. The results of GC work depends on how big are |
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* the UBIFS nodes GC deals with. Large nodes make GC waste more space. Indeed, |
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* if GC move data from LEB A to LEB B and nodes in LEB A are large, GC would |
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* have to waste large pieces of free space at the end of LEB B, because nodes |
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* from LEB A would not fit. And the worst situation is when all nodes are of |
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* maximum size. So dark watermark is the amount of free + dirty space in LEB |
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* which are guaranteed to be reclaimable. If LEB has less space, the GC might |
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* be unable to reclaim it. So, LEBs with free + dirty greater than dark |
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* watermark are "good" LEBs from GC's point of view. The other LEBs are not so |
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* good, and GC takes extra care when moving them. |
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*/ |
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|
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#include <linux/slab.h> |
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#include <linux/pagemap.h> |
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#include <linux/list_sort.h> |
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#include "ubifs.h" |
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|
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/* |
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* GC may need to move more than one LEB to make progress. The below constants |
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* define "soft" and "hard" limits on the number of LEBs the garbage collector |
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* may move. |
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*/ |
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#define SOFT_LEBS_LIMIT 4 |
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#define HARD_LEBS_LIMIT 32 |
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|
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/** |
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* switch_gc_head - switch the garbage collection journal head. |
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* @c: UBIFS file-system description object |
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* |
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* This function switch the GC head to the next LEB which is reserved in |
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* @c->gc_lnum. Returns %0 in case of success, %-EAGAIN if commit is required, |
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* and other negative error code in case of failures. |
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*/ |
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static int switch_gc_head(struct ubifs_info *c) |
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{ |
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int err, gc_lnum = c->gc_lnum; |
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struct ubifs_wbuf *wbuf = &c->jheads[GCHD].wbuf; |
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|
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ubifs_assert(c, gc_lnum != -1); |
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dbg_gc("switch GC head from LEB %d:%d to LEB %d (waste %d bytes)", |
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wbuf->lnum, wbuf->offs + wbuf->used, gc_lnum, |
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c->leb_size - wbuf->offs - wbuf->used); |
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|
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err = ubifs_wbuf_sync_nolock(wbuf); |
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if (err) |
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return err; |
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|
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/* |
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* The GC write-buffer was synchronized, we may safely unmap |
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* 'c->gc_lnum'. |
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*/ |
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err = ubifs_leb_unmap(c, gc_lnum); |
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if (err) |
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return err; |
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|
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err = ubifs_add_bud_to_log(c, GCHD, gc_lnum, 0); |
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if (err) |
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return err; |
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c->gc_lnum = -1; |
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err = ubifs_wbuf_seek_nolock(wbuf, gc_lnum, 0); |
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return err; |
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} |
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|
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/** |
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* data_nodes_cmp - compare 2 data nodes. |
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* @priv: UBIFS file-system description object |
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* @a: first data node |
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* @b: second data node |
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* |
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* This function compares data nodes @a and @b. Returns %1 if @a has greater |
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* inode or block number, and %-1 otherwise. |
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*/ |
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static int data_nodes_cmp(void *priv, struct list_head *a, struct list_head *b) |
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{ |
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ino_t inuma, inumb; |
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struct ubifs_info *c = priv; |
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struct ubifs_scan_node *sa, *sb; |
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|
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cond_resched(); |
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if (a == b) |
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return 0; |
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sa = list_entry(a, struct ubifs_scan_node, list); |
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sb = list_entry(b, struct ubifs_scan_node, list); |
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ubifs_assert(c, key_type(c, &sa->key) == UBIFS_DATA_KEY); |
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ubifs_assert(c, key_type(c, &sb->key) == UBIFS_DATA_KEY); |
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ubifs_assert(c, sa->type == UBIFS_DATA_NODE); |
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ubifs_assert(c, sb->type == UBIFS_DATA_NODE); |
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inuma = key_inum(c, &sa->key); |
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inumb = key_inum(c, &sb->key); |
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if (inuma == inumb) { |
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unsigned int blka = key_block(c, &sa->key); |
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unsigned int blkb = key_block(c, &sb->key); |
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|
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if (blka <= blkb) |
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return -1; |
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} else if (inuma <= inumb) |
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return -1; |
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return 1; |
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} |
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/* |
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* nondata_nodes_cmp - compare 2 non-data nodes. |
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* @priv: UBIFS file-system description object |
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* @a: first node |
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* @a: second node |
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* |
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* This function compares nodes @a and @b. It makes sure that inode nodes go |
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* first and sorted by length in descending order. Directory entry nodes go |
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* after inode nodes and are sorted in ascending hash valuer order. |
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*/ |
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static int nondata_nodes_cmp(void *priv, struct list_head *a, |
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struct list_head *b) |
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{ |
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ino_t inuma, inumb; |
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struct ubifs_info *c = priv; |
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struct ubifs_scan_node *sa, *sb; |
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cond_resched(); |
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if (a == b) |
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return 0; |
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sa = list_entry(a, struct ubifs_scan_node, list); |
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sb = list_entry(b, struct ubifs_scan_node, list); |
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ubifs_assert(c, key_type(c, &sa->key) != UBIFS_DATA_KEY && |
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key_type(c, &sb->key) != UBIFS_DATA_KEY); |
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ubifs_assert(c, sa->type != UBIFS_DATA_NODE && |
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sb->type != UBIFS_DATA_NODE); |
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/* Inodes go before directory entries */ |
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if (sa->type == UBIFS_INO_NODE) { |
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if (sb->type == UBIFS_INO_NODE) |
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return sb->len - sa->len; |
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return -1; |
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} |
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if (sb->type == UBIFS_INO_NODE) |
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return 1; |
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ubifs_assert(c, key_type(c, &sa->key) == UBIFS_DENT_KEY || |
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key_type(c, &sa->key) == UBIFS_XENT_KEY); |
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ubifs_assert(c, key_type(c, &sb->key) == UBIFS_DENT_KEY || |
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key_type(c, &sb->key) == UBIFS_XENT_KEY); |
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ubifs_assert(c, sa->type == UBIFS_DENT_NODE || |
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sa->type == UBIFS_XENT_NODE); |
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ubifs_assert(c, sb->type == UBIFS_DENT_NODE || |
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sb->type == UBIFS_XENT_NODE); |
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inuma = key_inum(c, &sa->key); |
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inumb = key_inum(c, &sb->key); |
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if (inuma == inumb) { |
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uint32_t hasha = key_hash(c, &sa->key); |
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uint32_t hashb = key_hash(c, &sb->key); |
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if (hasha <= hashb) |
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return -1; |
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} else if (inuma <= inumb) |
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return -1; |
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return 1; |
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} |
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|
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/** |
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* sort_nodes - sort nodes for GC. |
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* @c: UBIFS file-system description object |
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* @sleb: describes nodes to sort and contains the result on exit |
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* @nondata: contains non-data nodes on exit |
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* @min: minimum node size is returned here |
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* |
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* This function sorts the list of inodes to garbage collect. First of all, it |
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* kills obsolete nodes and separates data and non-data nodes to the |
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* @sleb->nodes and @nondata lists correspondingly. |
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* |
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* Data nodes are then sorted in block number order - this is important for |
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* bulk-read; data nodes with lower inode number go before data nodes with |
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* higher inode number, and data nodes with lower block number go before data |
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* nodes with higher block number; |
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* |
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* Non-data nodes are sorted as follows. |
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* o First go inode nodes - they are sorted in descending length order. |
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* o Then go directory entry nodes - they are sorted in hash order, which |
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* should supposedly optimize 'readdir()'. Direntry nodes with lower parent |
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* inode number go before direntry nodes with higher parent inode number, |
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* and direntry nodes with lower name hash values go before direntry nodes |
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* with higher name hash values. |
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* |
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* This function returns zero in case of success and a negative error code in |
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* case of failure. |
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*/ |
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static int sort_nodes(struct ubifs_info *c, struct ubifs_scan_leb *sleb, |
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struct list_head *nondata, int *min) |
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{ |
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int err; |
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struct ubifs_scan_node *snod, *tmp; |
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*min = INT_MAX; |
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|
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/* Separate data nodes and non-data nodes */ |
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list_for_each_entry_safe(snod, tmp, &sleb->nodes, list) { |
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ubifs_assert(c, snod->type == UBIFS_INO_NODE || |
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snod->type == UBIFS_DATA_NODE || |
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snod->type == UBIFS_DENT_NODE || |
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snod->type == UBIFS_XENT_NODE || |
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snod->type == UBIFS_TRUN_NODE || |
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snod->type == UBIFS_AUTH_NODE); |
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|
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if (snod->type != UBIFS_INO_NODE && |
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snod->type != UBIFS_DATA_NODE && |
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snod->type != UBIFS_DENT_NODE && |
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snod->type != UBIFS_XENT_NODE) { |
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/* Probably truncation node, zap it */ |
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list_del(&snod->list); |
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kfree(snod); |
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continue; |
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} |
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ubifs_assert(c, key_type(c, &snod->key) == UBIFS_DATA_KEY || |
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key_type(c, &snod->key) == UBIFS_INO_KEY || |
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key_type(c, &snod->key) == UBIFS_DENT_KEY || |
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key_type(c, &snod->key) == UBIFS_XENT_KEY); |
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err = ubifs_tnc_has_node(c, &snod->key, 0, sleb->lnum, |
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snod->offs, 0); |
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if (err < 0) |
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return err; |
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if (!err) { |
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/* The node is obsolete, remove it from the list */ |
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list_del(&snod->list); |
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kfree(snod); |
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continue; |
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} |
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if (snod->len < *min) |
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*min = snod->len; |
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if (key_type(c, &snod->key) != UBIFS_DATA_KEY) |
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list_move_tail(&snod->list, nondata); |
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} |
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/* Sort data and non-data nodes */ |
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list_sort(c, &sleb->nodes, &data_nodes_cmp); |
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list_sort(c, nondata, &nondata_nodes_cmp); |
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|
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err = dbg_check_data_nodes_order(c, &sleb->nodes); |
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if (err) |
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return err; |
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err = dbg_check_nondata_nodes_order(c, nondata); |
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if (err) |
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return err; |
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return 0; |
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} |
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/** |
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* move_node - move a node. |
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* @c: UBIFS file-system description object |
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* @sleb: describes the LEB to move nodes from |
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* @snod: the mode to move |
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* @wbuf: write-buffer to move node to |
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* |
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* This function moves node @snod to @wbuf, changes TNC correspondingly, and |
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* destroys @snod. Returns zero in case of success and a negative error code in |
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* case of failure. |
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*/ |
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static int move_node(struct ubifs_info *c, struct ubifs_scan_leb *sleb, |
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struct ubifs_scan_node *snod, struct ubifs_wbuf *wbuf) |
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{ |
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int err, new_lnum = wbuf->lnum, new_offs = wbuf->offs + wbuf->used; |
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|
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cond_resched(); |
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err = ubifs_wbuf_write_nolock(wbuf, snod->node, snod->len); |
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if (err) |
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return err; |
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err = ubifs_tnc_replace(c, &snod->key, sleb->lnum, |
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snod->offs, new_lnum, new_offs, |
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snod->len); |
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list_del(&snod->list); |
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kfree(snod); |
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return err; |
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} |
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/** |
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* move_nodes - move nodes. |
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* @c: UBIFS file-system description object |
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* @sleb: describes the LEB to move nodes from |
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* |
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* This function moves valid nodes from data LEB described by @sleb to the GC |
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* journal head. This function returns zero in case of success, %-EAGAIN if |
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* commit is required, and other negative error codes in case of other |
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* failures. |
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*/ |
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static int move_nodes(struct ubifs_info *c, struct ubifs_scan_leb *sleb) |
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{ |
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int err, min; |
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LIST_HEAD(nondata); |
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struct ubifs_wbuf *wbuf = &c->jheads[GCHD].wbuf; |
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|
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if (wbuf->lnum == -1) { |
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/* |
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* The GC journal head is not set, because it is the first GC |
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* invocation since mount. |
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*/ |
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err = switch_gc_head(c); |
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if (err) |
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return err; |
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} |
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err = sort_nodes(c, sleb, &nondata, &min); |
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if (err) |
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goto out; |
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|
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/* Write nodes to their new location. Use the first-fit strategy */ |
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while (1) { |
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int avail, moved = 0; |
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struct ubifs_scan_node *snod, *tmp; |
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|
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/* Move data nodes */ |
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list_for_each_entry_safe(snod, tmp, &sleb->nodes, list) { |
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avail = c->leb_size - wbuf->offs - wbuf->used - |
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ubifs_auth_node_sz(c); |
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if (snod->len > avail) |
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/* |
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* Do not skip data nodes in order to optimize |
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* bulk-read. |
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*/ |
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break; |
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err = ubifs_shash_update(c, c->jheads[GCHD].log_hash, |
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snod->node, snod->len); |
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if (err) |
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goto out; |
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|
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err = move_node(c, sleb, snod, wbuf); |
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if (err) |
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goto out; |
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moved = 1; |
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} |
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|
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/* Move non-data nodes */ |
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list_for_each_entry_safe(snod, tmp, &nondata, list) { |
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avail = c->leb_size - wbuf->offs - wbuf->used - |
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ubifs_auth_node_sz(c); |
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if (avail < min) |
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break; |
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|
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if (snod->len > avail) { |
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/* |
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* Keep going only if this is an inode with |
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* some data. Otherwise stop and switch the GC |
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* head. IOW, we assume that data-less inode |
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* nodes and direntry nodes are roughly of the |
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* same size. |
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*/ |
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if (key_type(c, &snod->key) == UBIFS_DENT_KEY || |
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snod->len == UBIFS_INO_NODE_SZ) |
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break; |
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continue; |
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} |
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err = ubifs_shash_update(c, c->jheads[GCHD].log_hash, |
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snod->node, snod->len); |
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if (err) |
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goto out; |
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err = move_node(c, sleb, snod, wbuf); |
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if (err) |
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goto out; |
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moved = 1; |
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} |
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|
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if (ubifs_authenticated(c) && moved) { |
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struct ubifs_auth_node *auth; |
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|
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auth = kmalloc(ubifs_auth_node_sz(c), GFP_NOFS); |
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if (!auth) { |
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err = -ENOMEM; |
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goto out; |
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} |
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|
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err = ubifs_prepare_auth_node(c, auth, |
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c->jheads[GCHD].log_hash); |
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if (err) { |
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kfree(auth); |
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goto out; |
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} |
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|
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err = ubifs_wbuf_write_nolock(wbuf, auth, |
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ubifs_auth_node_sz(c)); |
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if (err) { |
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kfree(auth); |
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goto out; |
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} |
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|
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ubifs_add_dirt(c, wbuf->lnum, ubifs_auth_node_sz(c)); |
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} |
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|
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if (list_empty(&sleb->nodes) && list_empty(&nondata)) |
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break; |
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|
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/* |
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* Waste the rest of the space in the LEB and switch to the |
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* next LEB. |
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*/ |
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err = switch_gc_head(c); |
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if (err) |
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goto out; |
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} |
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|
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return 0; |
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|
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out: |
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list_splice_tail(&nondata, &sleb->nodes); |
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return err; |
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} |
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|
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/** |
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* gc_sync_wbufs - sync write-buffers for GC. |
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* @c: UBIFS file-system description object |
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* |
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* We must guarantee that obsoleting nodes are on flash. Unfortunately they may |
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* be in a write-buffer instead. That is, a node could be written to a |
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* write-buffer, obsoleting another node in a LEB that is GC'd. If that LEB is |
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* erased before the write-buffer is sync'd and then there is an unclean |
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* unmount, then an existing node is lost. To avoid this, we sync all |
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* write-buffers. |
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* |
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* This function returns %0 on success or a negative error code on failure. |
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*/ |
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static int gc_sync_wbufs(struct ubifs_info *c) |
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{ |
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int err, i; |
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|
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for (i = 0; i < c->jhead_cnt; i++) { |
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if (i == GCHD) |
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continue; |
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err = ubifs_wbuf_sync(&c->jheads[i].wbuf); |
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if (err) |
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return err; |
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} |
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return 0; |
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} |
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|
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/** |
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* ubifs_garbage_collect_leb - garbage-collect a logical eraseblock. |
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* @c: UBIFS file-system description object |
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* @lp: describes the LEB to garbage collect |
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* |
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* This function garbage-collects an LEB and returns one of the @LEB_FREED, |
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* @LEB_RETAINED, etc positive codes in case of success, %-EAGAIN if commit is |
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* required, and other negative error codes in case of failures. |
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*/ |
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int ubifs_garbage_collect_leb(struct ubifs_info *c, struct ubifs_lprops *lp) |
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{ |
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struct ubifs_scan_leb *sleb; |
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struct ubifs_scan_node *snod; |
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struct ubifs_wbuf *wbuf = &c->jheads[GCHD].wbuf; |
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int err = 0, lnum = lp->lnum; |
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|
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ubifs_assert(c, c->gc_lnum != -1 || wbuf->offs + wbuf->used == 0 || |
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c->need_recovery); |
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ubifs_assert(c, c->gc_lnum != lnum); |
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ubifs_assert(c, wbuf->lnum != lnum); |
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|
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if (lp->free + lp->dirty == c->leb_size) { |
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/* Special case - a free LEB */ |
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dbg_gc("LEB %d is free, return it", lp->lnum); |
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ubifs_assert(c, !(lp->flags & LPROPS_INDEX)); |
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|
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if (lp->free != c->leb_size) { |
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/* |
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* Write buffers must be sync'd before unmapping |
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* freeable LEBs, because one of them may contain data |
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* which obsoletes something in 'lp->lnum'. |
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*/ |
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err = gc_sync_wbufs(c); |
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if (err) |
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return err; |
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err = ubifs_change_one_lp(c, lp->lnum, c->leb_size, |
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0, 0, 0, 0); |
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if (err) |
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return err; |
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} |
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err = ubifs_leb_unmap(c, lp->lnum); |
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if (err) |
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return err; |
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|
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if (c->gc_lnum == -1) { |
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c->gc_lnum = lnum; |
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return LEB_RETAINED; |
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} |
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|
|
return LEB_FREED; |
|
} |
|
|
|
/* |
|
* We scan the entire LEB even though we only really need to scan up to |
|
* (c->leb_size - lp->free). |
|
*/ |
|
sleb = ubifs_scan(c, lnum, 0, c->sbuf, 0); |
|
if (IS_ERR(sleb)) |
|
return PTR_ERR(sleb); |
|
|
|
ubifs_assert(c, !list_empty(&sleb->nodes)); |
|
snod = list_entry(sleb->nodes.next, struct ubifs_scan_node, list); |
|
|
|
if (snod->type == UBIFS_IDX_NODE) { |
|
struct ubifs_gced_idx_leb *idx_gc; |
|
|
|
dbg_gc("indexing LEB %d (free %d, dirty %d)", |
|
lnum, lp->free, lp->dirty); |
|
list_for_each_entry(snod, &sleb->nodes, list) { |
|
struct ubifs_idx_node *idx = snod->node; |
|
int level = le16_to_cpu(idx->level); |
|
|
|
ubifs_assert(c, snod->type == UBIFS_IDX_NODE); |
|
key_read(c, ubifs_idx_key(c, idx), &snod->key); |
|
err = ubifs_dirty_idx_node(c, &snod->key, level, lnum, |
|
snod->offs); |
|
if (err) |
|
goto out; |
|
} |
|
|
|
idx_gc = kmalloc(sizeof(struct ubifs_gced_idx_leb), GFP_NOFS); |
|
if (!idx_gc) { |
|
err = -ENOMEM; |
|
goto out; |
|
} |
|
|
|
idx_gc->lnum = lnum; |
|
idx_gc->unmap = 0; |
|
list_add(&idx_gc->list, &c->idx_gc); |
|
|
|
/* |
|
* Don't release the LEB until after the next commit, because |
|
* it may contain data which is needed for recovery. So |
|
* although we freed this LEB, it will become usable only after |
|
* the commit. |
|
*/ |
|
err = ubifs_change_one_lp(c, lnum, c->leb_size, 0, 0, |
|
LPROPS_INDEX, 1); |
|
if (err) |
|
goto out; |
|
err = LEB_FREED_IDX; |
|
} else { |
|
dbg_gc("data LEB %d (free %d, dirty %d)", |
|
lnum, lp->free, lp->dirty); |
|
|
|
err = move_nodes(c, sleb); |
|
if (err) |
|
goto out_inc_seq; |
|
|
|
err = gc_sync_wbufs(c); |
|
if (err) |
|
goto out_inc_seq; |
|
|
|
err = ubifs_change_one_lp(c, lnum, c->leb_size, 0, 0, 0, 0); |
|
if (err) |
|
goto out_inc_seq; |
|
|
|
/* Allow for races with TNC */ |
|
c->gced_lnum = lnum; |
|
smp_wmb(); |
|
c->gc_seq += 1; |
|
smp_wmb(); |
|
|
|
if (c->gc_lnum == -1) { |
|
c->gc_lnum = lnum; |
|
err = LEB_RETAINED; |
|
} else { |
|
err = ubifs_wbuf_sync_nolock(wbuf); |
|
if (err) |
|
goto out; |
|
|
|
err = ubifs_leb_unmap(c, lnum); |
|
if (err) |
|
goto out; |
|
|
|
err = LEB_FREED; |
|
} |
|
} |
|
|
|
out: |
|
ubifs_scan_destroy(sleb); |
|
return err; |
|
|
|
out_inc_seq: |
|
/* We may have moved at least some nodes so allow for races with TNC */ |
|
c->gced_lnum = lnum; |
|
smp_wmb(); |
|
c->gc_seq += 1; |
|
smp_wmb(); |
|
goto out; |
|
} |
|
|
|
/** |
|
* ubifs_garbage_collect - UBIFS garbage collector. |
|
* @c: UBIFS file-system description object |
|
* @anyway: do GC even if there are free LEBs |
|
* |
|
* This function does out-of-place garbage collection. The return codes are: |
|
* o positive LEB number if the LEB has been freed and may be used; |
|
* o %-EAGAIN if the caller has to run commit; |
|
* o %-ENOSPC if GC failed to make any progress; |
|
* o other negative error codes in case of other errors. |
|
* |
|
* Garbage collector writes data to the journal when GC'ing data LEBs, and just |
|
* marking indexing nodes dirty when GC'ing indexing LEBs. Thus, at some point |
|
* commit may be required. But commit cannot be run from inside GC, because the |
|
* caller might be holding the commit lock, so %-EAGAIN is returned instead; |
|
* And this error code means that the caller has to run commit, and re-run GC |
|
* if there is still no free space. |
|
* |
|
* There are many reasons why this function may return %-EAGAIN: |
|
* o the log is full and there is no space to write an LEB reference for |
|
* @c->gc_lnum; |
|
* o the journal is too large and exceeds size limitations; |
|
* o GC moved indexing LEBs, but they can be used only after the commit; |
|
* o the shrinker fails to find clean znodes to free and requests the commit; |
|
* o etc. |
|
* |
|
* Note, if the file-system is close to be full, this function may return |
|
* %-EAGAIN infinitely, so the caller has to limit amount of re-invocations of |
|
* the function. E.g., this happens if the limits on the journal size are too |
|
* tough and GC writes too much to the journal before an LEB is freed. This |
|
* might also mean that the journal is too large, and the TNC becomes to big, |
|
* so that the shrinker is constantly called, finds not clean znodes to free, |
|
* and requests commit. Well, this may also happen if the journal is all right, |
|
* but another kernel process consumes too much memory. Anyway, infinite |
|
* %-EAGAIN may happen, but in some extreme/misconfiguration cases. |
|
*/ |
|
int ubifs_garbage_collect(struct ubifs_info *c, int anyway) |
|
{ |
|
int i, err, ret, min_space = c->dead_wm; |
|
struct ubifs_lprops lp; |
|
struct ubifs_wbuf *wbuf = &c->jheads[GCHD].wbuf; |
|
|
|
ubifs_assert_cmt_locked(c); |
|
ubifs_assert(c, !c->ro_media && !c->ro_mount); |
|
|
|
if (ubifs_gc_should_commit(c)) |
|
return -EAGAIN; |
|
|
|
mutex_lock_nested(&wbuf->io_mutex, wbuf->jhead); |
|
|
|
if (c->ro_error) { |
|
ret = -EROFS; |
|
goto out_unlock; |
|
} |
|
|
|
/* We expect the write-buffer to be empty on entry */ |
|
ubifs_assert(c, !wbuf->used); |
|
|
|
for (i = 0; ; i++) { |
|
int space_before, space_after; |
|
|
|
cond_resched(); |
|
|
|
/* Give the commit an opportunity to run */ |
|
if (ubifs_gc_should_commit(c)) { |
|
ret = -EAGAIN; |
|
break; |
|
} |
|
|
|
if (i > SOFT_LEBS_LIMIT && !list_empty(&c->idx_gc)) { |
|
/* |
|
* We've done enough iterations. Indexing LEBs were |
|
* moved and will be available after the commit. |
|
*/ |
|
dbg_gc("soft limit, some index LEBs GC'ed, -EAGAIN"); |
|
ubifs_commit_required(c); |
|
ret = -EAGAIN; |
|
break; |
|
} |
|
|
|
if (i > HARD_LEBS_LIMIT) { |
|
/* |
|
* We've moved too many LEBs and have not made |
|
* progress, give up. |
|
*/ |
|
dbg_gc("hard limit, -ENOSPC"); |
|
ret = -ENOSPC; |
|
break; |
|
} |
|
|
|
/* |
|
* Empty and freeable LEBs can turn up while we waited for |
|
* the wbuf lock, or while we have been running GC. In that |
|
* case, we should just return one of those instead of |
|
* continuing to GC dirty LEBs. Hence we request |
|
* 'ubifs_find_dirty_leb()' to return an empty LEB if it can. |
|
*/ |
|
ret = ubifs_find_dirty_leb(c, &lp, min_space, anyway ? 0 : 1); |
|
if (ret) { |
|
if (ret == -ENOSPC) |
|
dbg_gc("no more dirty LEBs"); |
|
break; |
|
} |
|
|
|
dbg_gc("found LEB %d: free %d, dirty %d, sum %d (min. space %d)", |
|
lp.lnum, lp.free, lp.dirty, lp.free + lp.dirty, |
|
min_space); |
|
|
|
space_before = c->leb_size - wbuf->offs - wbuf->used; |
|
if (wbuf->lnum == -1) |
|
space_before = 0; |
|
|
|
ret = ubifs_garbage_collect_leb(c, &lp); |
|
if (ret < 0) { |
|
if (ret == -EAGAIN) { |
|
/* |
|
* This is not error, so we have to return the |
|
* LEB to lprops. But if 'ubifs_return_leb()' |
|
* fails, its failure code is propagated to the |
|
* caller instead of the original '-EAGAIN'. |
|
*/ |
|
err = ubifs_return_leb(c, lp.lnum); |
|
if (err) |
|
ret = err; |
|
break; |
|
} |
|
goto out; |
|
} |
|
|
|
if (ret == LEB_FREED) { |
|
/* An LEB has been freed and is ready for use */ |
|
dbg_gc("LEB %d freed, return", lp.lnum); |
|
ret = lp.lnum; |
|
break; |
|
} |
|
|
|
if (ret == LEB_FREED_IDX) { |
|
/* |
|
* This was an indexing LEB and it cannot be |
|
* immediately used. And instead of requesting the |
|
* commit straight away, we try to garbage collect some |
|
* more. |
|
*/ |
|
dbg_gc("indexing LEB %d freed, continue", lp.lnum); |
|
continue; |
|
} |
|
|
|
ubifs_assert(c, ret == LEB_RETAINED); |
|
space_after = c->leb_size - wbuf->offs - wbuf->used; |
|
dbg_gc("LEB %d retained, freed %d bytes", lp.lnum, |
|
space_after - space_before); |
|
|
|
if (space_after > space_before) { |
|
/* GC makes progress, keep working */ |
|
min_space >>= 1; |
|
if (min_space < c->dead_wm) |
|
min_space = c->dead_wm; |
|
continue; |
|
} |
|
|
|
dbg_gc("did not make progress"); |
|
|
|
/* |
|
* GC moved an LEB bud have not done any progress. This means |
|
* that the previous GC head LEB contained too few free space |
|
* and the LEB which was GC'ed contained only large nodes which |
|
* did not fit that space. |
|
* |
|
* We can do 2 things: |
|
* 1. pick another LEB in a hope it'll contain a small node |
|
* which will fit the space we have at the end of current GC |
|
* head LEB, but there is no guarantee, so we try this out |
|
* unless we have already been working for too long; |
|
* 2. request an LEB with more dirty space, which will force |
|
* 'ubifs_find_dirty_leb()' to start scanning the lprops |
|
* table, instead of just picking one from the heap |
|
* (previously it already picked the dirtiest LEB). |
|
*/ |
|
if (i < SOFT_LEBS_LIMIT) { |
|
dbg_gc("try again"); |
|
continue; |
|
} |
|
|
|
min_space <<= 1; |
|
if (min_space > c->dark_wm) |
|
min_space = c->dark_wm; |
|
dbg_gc("set min. space to %d", min_space); |
|
} |
|
|
|
if (ret == -ENOSPC && !list_empty(&c->idx_gc)) { |
|
dbg_gc("no space, some index LEBs GC'ed, -EAGAIN"); |
|
ubifs_commit_required(c); |
|
ret = -EAGAIN; |
|
} |
|
|
|
err = ubifs_wbuf_sync_nolock(wbuf); |
|
if (!err) |
|
err = ubifs_leb_unmap(c, c->gc_lnum); |
|
if (err) { |
|
ret = err; |
|
goto out; |
|
} |
|
out_unlock: |
|
mutex_unlock(&wbuf->io_mutex); |
|
return ret; |
|
|
|
out: |
|
ubifs_assert(c, ret < 0); |
|
ubifs_assert(c, ret != -ENOSPC && ret != -EAGAIN); |
|
ubifs_wbuf_sync_nolock(wbuf); |
|
ubifs_ro_mode(c, ret); |
|
mutex_unlock(&wbuf->io_mutex); |
|
ubifs_return_leb(c, lp.lnum); |
|
return ret; |
|
} |
|
|
|
/** |
|
* ubifs_gc_start_commit - garbage collection at start of commit. |
|
* @c: UBIFS file-system description object |
|
* |
|
* If a LEB has only dirty and free space, then we may safely unmap it and make |
|
* it free. Note, we cannot do this with indexing LEBs because dirty space may |
|
* correspond index nodes that are required for recovery. In that case, the |
|
* LEB cannot be unmapped until after the next commit. |
|
* |
|
* This function returns %0 upon success and a negative error code upon failure. |
|
*/ |
|
int ubifs_gc_start_commit(struct ubifs_info *c) |
|
{ |
|
struct ubifs_gced_idx_leb *idx_gc; |
|
const struct ubifs_lprops *lp; |
|
int err = 0, flags; |
|
|
|
ubifs_get_lprops(c); |
|
|
|
/* |
|
* Unmap (non-index) freeable LEBs. Note that recovery requires that all |
|
* wbufs are sync'd before this, which is done in 'do_commit()'. |
|
*/ |
|
while (1) { |
|
lp = ubifs_fast_find_freeable(c); |
|
if (!lp) |
|
break; |
|
ubifs_assert(c, !(lp->flags & LPROPS_TAKEN)); |
|
ubifs_assert(c, !(lp->flags & LPROPS_INDEX)); |
|
err = ubifs_leb_unmap(c, lp->lnum); |
|
if (err) |
|
goto out; |
|
lp = ubifs_change_lp(c, lp, c->leb_size, 0, lp->flags, 0); |
|
if (IS_ERR(lp)) { |
|
err = PTR_ERR(lp); |
|
goto out; |
|
} |
|
ubifs_assert(c, !(lp->flags & LPROPS_TAKEN)); |
|
ubifs_assert(c, !(lp->flags & LPROPS_INDEX)); |
|
} |
|
|
|
/* Mark GC'd index LEBs OK to unmap after this commit finishes */ |
|
list_for_each_entry(idx_gc, &c->idx_gc, list) |
|
idx_gc->unmap = 1; |
|
|
|
/* Record index freeable LEBs for unmapping after commit */ |
|
while (1) { |
|
lp = ubifs_fast_find_frdi_idx(c); |
|
if (IS_ERR(lp)) { |
|
err = PTR_ERR(lp); |
|
goto out; |
|
} |
|
if (!lp) |
|
break; |
|
idx_gc = kmalloc(sizeof(struct ubifs_gced_idx_leb), GFP_NOFS); |
|
if (!idx_gc) { |
|
err = -ENOMEM; |
|
goto out; |
|
} |
|
ubifs_assert(c, !(lp->flags & LPROPS_TAKEN)); |
|
ubifs_assert(c, lp->flags & LPROPS_INDEX); |
|
/* Don't release the LEB until after the next commit */ |
|
flags = (lp->flags | LPROPS_TAKEN) ^ LPROPS_INDEX; |
|
lp = ubifs_change_lp(c, lp, c->leb_size, 0, flags, 1); |
|
if (IS_ERR(lp)) { |
|
err = PTR_ERR(lp); |
|
kfree(idx_gc); |
|
goto out; |
|
} |
|
ubifs_assert(c, lp->flags & LPROPS_TAKEN); |
|
ubifs_assert(c, !(lp->flags & LPROPS_INDEX)); |
|
idx_gc->lnum = lp->lnum; |
|
idx_gc->unmap = 1; |
|
list_add(&idx_gc->list, &c->idx_gc); |
|
} |
|
out: |
|
ubifs_release_lprops(c); |
|
return err; |
|
} |
|
|
|
/** |
|
* ubifs_gc_end_commit - garbage collection at end of commit. |
|
* @c: UBIFS file-system description object |
|
* |
|
* This function completes out-of-place garbage collection of index LEBs. |
|
*/ |
|
int ubifs_gc_end_commit(struct ubifs_info *c) |
|
{ |
|
struct ubifs_gced_idx_leb *idx_gc, *tmp; |
|
struct ubifs_wbuf *wbuf; |
|
int err = 0; |
|
|
|
wbuf = &c->jheads[GCHD].wbuf; |
|
mutex_lock_nested(&wbuf->io_mutex, wbuf->jhead); |
|
list_for_each_entry_safe(idx_gc, tmp, &c->idx_gc, list) |
|
if (idx_gc->unmap) { |
|
dbg_gc("LEB %d", idx_gc->lnum); |
|
err = ubifs_leb_unmap(c, idx_gc->lnum); |
|
if (err) |
|
goto out; |
|
err = ubifs_change_one_lp(c, idx_gc->lnum, LPROPS_NC, |
|
LPROPS_NC, 0, LPROPS_TAKEN, -1); |
|
if (err) |
|
goto out; |
|
list_del(&idx_gc->list); |
|
kfree(idx_gc); |
|
} |
|
out: |
|
mutex_unlock(&wbuf->io_mutex); |
|
return err; |
|
} |
|
|
|
/** |
|
* ubifs_destroy_idx_gc - destroy idx_gc list. |
|
* @c: UBIFS file-system description object |
|
* |
|
* This function destroys the @c->idx_gc list. It is called when unmounting |
|
* so locks are not needed. Returns zero in case of success and a negative |
|
* error code in case of failure. |
|
*/ |
|
void ubifs_destroy_idx_gc(struct ubifs_info *c) |
|
{ |
|
while (!list_empty(&c->idx_gc)) { |
|
struct ubifs_gced_idx_leb *idx_gc; |
|
|
|
idx_gc = list_entry(c->idx_gc.next, struct ubifs_gced_idx_leb, |
|
list); |
|
c->idx_gc_cnt -= 1; |
|
list_del(&idx_gc->list); |
|
kfree(idx_gc); |
|
} |
|
} |
|
|
|
/** |
|
* ubifs_get_idx_gc_leb - get a LEB from GC'd index LEB list. |
|
* @c: UBIFS file-system description object |
|
* |
|
* Called during start commit so locks are not needed. |
|
*/ |
|
int ubifs_get_idx_gc_leb(struct ubifs_info *c) |
|
{ |
|
struct ubifs_gced_idx_leb *idx_gc; |
|
int lnum; |
|
|
|
if (list_empty(&c->idx_gc)) |
|
return -ENOSPC; |
|
idx_gc = list_entry(c->idx_gc.next, struct ubifs_gced_idx_leb, list); |
|
lnum = idx_gc->lnum; |
|
/* c->idx_gc_cnt is updated by the caller when lprops are updated */ |
|
list_del(&idx_gc->list); |
|
kfree(idx_gc); |
|
return lnum; |
|
}
|
|
|