- 根目录:
- fs
- ubifs
- gc.c
/*
* This file is part of UBIFS.
*
* Copyright (C) 2006-2008 Nokia Corporation.
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 as published by
* the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
* more details.
*
* You should have received a copy of the GNU General Public License along with
* this program; if not, write to the Free Software Foundation, Inc., 51
* Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*
* Authors: Adrian Hunter
* Artem Bityutskiy (Битюцкий Артём)
*/
/*
* This file implements garbage collection. The procedure for garbage collection
* is different depending on whether a LEB as an index LEB (contains index
* nodes) or not. For non-index LEBs, garbage collection finds a LEB which
* contains a lot of dirty space (obsolete nodes), and copies the non-obsolete
* nodes to the journal, at which point the garbage-collected LEB is free to be
* reused. For index LEBs, garbage collection marks the non-obsolete index nodes
* dirty in the TNC, and after the next commit, the garbage-collected LEB is
* to be reused. Garbage collection will cause the number of dirty index nodes
* to grow, however sufficient space is reserved for the index to ensure the
* commit will never run out of space.
*
* Notes about dead watermark. At current UBIFS implementation we assume that
* LEBs which have less than @c->dead_wm bytes of free + dirty space are full
* and not worth garbage-collecting. The dead watermark is one min. I/O unit
* size, or min. UBIFS node size, depending on what is greater. Indeed, UBIFS
* Garbage Collector has to synchronize the GC head's write buffer before
* returning, so this is about wasting one min. I/O unit. However, UBIFS GC can
* actually reclaim even very small pieces of dirty space by garbage collecting
* enough dirty LEBs, but we do not bother doing this at this implementation.
*
* Notes about dark watermark. The results of GC work depends on how big are
* the UBIFS nodes GC deals with. Large nodes make GC waste more space. Indeed,
* if GC move data from LEB A to LEB B and nodes in LEB A are large, GC would
* have to waste large pieces of free space at the end of LEB B, because nodes
* from LEB A would not fit. And the worst situation is when all nodes are of
* maximum size. So dark watermark is the amount of free + dirty space in LEB
* which are guaranteed to be reclaimable. If LEB has less space, the GC might
* be unable to reclaim it. So, LEBs with free + dirty greater than dark
* watermark are "good" LEBs from GC's point of few. The other LEBs are not so
* good, and GC takes extra care when moving them.
*/
#include <linux/slab.h>
#include <linux/pagemap.h>
#include <linux/list_sort.h>
#include "ubifs.h"
/*
* GC may need to move more than one LEB to make progress. The below constants
* define "soft" and "hard" limits on the number of LEBs the garbage collector
* may move.
*/
#define SOFT_LEBS_LIMIT 4
#define HARD_LEBS_LIMIT 32
/**
* switch_gc_head - switch the garbage collection journal head.
* @c: UBIFS file-system description object
* @buf: buffer to write
* @len: length of the buffer to write
* @lnum: LEB number written is returned here
* @offs: offset written is returned here
*
* This function switch the GC head to the next LEB which is reserved in
* @c->gc_lnum. Returns %0 in case of success, %-EAGAIN if commit is required,
* and other negative error code in case of failures.
*/
static int switch_gc_head(struct ubifs_info *c)
{
int err, gc_lnum = c->gc_lnum;
struct ubifs_wbuf *wbuf = &c->jheads[GCHD].wbuf;
ubifs_assert(gc_lnum != -1);
dbg_gc("switch GC head from LEB %d:%d to LEB %d (waste %d bytes)",
wbuf->lnum, wbuf->offs + wbuf->used, gc_lnum,
c->leb_size - wbuf->offs - wbuf->used);
err = ubifs_wbuf_sync_nolock(wbuf);
if (err)
return err;
/*
* The GC write-buffer was synchronized, we may safely unmap
* 'c->gc_lnum'.
*/
err = ubifs_leb_unmap(c, gc_lnum);
if (err)
return err;
err = ubifs_add_bud_to_log(c, GCHD, gc_lnum, 0);
if (err)
return err;
c->gc_lnum = -1;
err = ubifs_wbuf_seek_nolock(wbuf, gc_lnum, 0, UBI_LONGTERM);
return err;
}
/**
* data_nodes_cmp - compare 2 data nodes.
* @priv: UBIFS file-system description object
* @a: first data node
* @a: second data node
*
* This function compares data nodes @a and @b. Returns %1 if @a has greater
* inode or block number, and %-1 otherwise.
*/
int data_nodes_cmp(void *priv, struct list_head *a, struct list_head *b)
{
ino_t inuma, inumb;
struct ubifs_info *c = priv;
struct ubifs_scan_node *sa, *sb;
cond_resched();
if (a == b)
return 0;
sa = list_entry(a, struct ubifs_scan_node, list);
sb = list_entry(b, struct ubifs_scan_node, list);
ubifs_assert(key_type(c, &sa->key) == UBIFS_DATA_KEY);
ubifs_assert(key_type(c, &sb->key) == UBIFS_DATA_KEY);
ubifs_assert(sa->type == UBIFS_DATA_NODE);
ubifs_assert(sb->type == UBIFS_DATA_NODE);
inuma = key_inum(c, &sa->key);
inumb = key_inum(c, &sb->key);
if (inuma == inumb) {
unsigned int blka = key_block(c, &sa->key);
unsigned int blkb = key_block(c, &sb->key);
if (blka <= blkb)
return -1;
} else if (inuma <= inumb)
return -1;
return 1;
}
/*
* nondata_nodes_cmp - compare 2 non-data nodes.
* @priv: UBIFS file-system description object
* @a: first node
* @a: second node
*
* This function compares nodes @a and @b. It makes sure that inode nodes go
* first and sorted by length in descending order. Directory entry nodes go
* after inode nodes and are sorted in ascending hash valuer order.
*/
int nondata_nodes_cmp(void *priv, struct list_head *a, struct list_head *b)
{
ino_t inuma, inumb;
struct ubifs_info *c = priv;
struct ubifs_scan_node *sa, *sb;
cond_resched();
if (a == b)
return 0;
sa = list_entry(a, struct ubifs_scan_node, list);
sb = list_entry(b, struct ubifs_scan_node, list);
ubifs_assert(key_type(c, &sa->key) != UBIFS_DATA_KEY &&
key_type(c, &sb->key) != UBIFS_DATA_KEY);
ubifs_assert(sa->type != UBIFS_DATA_NODE &&
sb->type != UBIFS_DATA_NODE);
/* Inodes go before directory entries */
if (sa->type == UBIFS_INO_NODE) {
if (sb->type == UBIFS_INO_NODE)
return sb->len - sa->len;
return -1;
}
if (sb->type == UBIFS_INO_NODE)
return 1;
ubifs_assert(key_type(c, &sa->key) == UBIFS_DENT_KEY ||
key_type(c, &sa->key) == UBIFS_XENT_KEY);
ubifs_assert(key_type(c, &sb->key) == UBIFS_DENT_KEY ||
key_type(c, &sb->key) == UBIFS_XENT_KEY);
ubifs_assert(sa->type == UBIFS_DENT_NODE ||
sa->type == UBIFS_XENT_NODE);
ubifs_assert(sb->type == UBIFS_DENT_NODE ||
sb->type == UBIFS_XENT_NODE);
inuma = key_inum(c, &sa->key);
inumb = key_inum(c, &sb->key);
if (inuma == inumb) {
uint32_t hasha = key_hash(c, &sa->key);
uint32_t hashb = key_hash(c, &sb->key);
if (hasha <= hashb)
return -1;
} else if (inuma <= inumb)
return -1;
return 1;
}
/**
* sort_nodes - sort nodes for GC.
* @c: UBIFS file-system description object
* @sleb: describes nodes to sort and contains the result on exit
* @nondata: contains non-data nodes on exit
* @min: minimum node size is returned here
*
* This function sorts the list of inodes to garbage collect. First of all, it
* kills obsolete nodes and separates data and non-data nodes to the
* @sleb->nodes and @nondata lists correspondingly.
*
* Data nodes are then sorted in block number order - this is important for
* bulk-read; data nodes with lower inode number go before data nodes with
* higher inode number, and data nodes with lower block number go before data
* nodes with higher block number;
*
* Non-data nodes are sorted as follows.
* o First go inode nodes - they are sorted in descending length order.
* o Then go directory entry nodes - they are sorted in hash order, which
* should supposedly optimize 'readdir()'. Direntry nodes with lower parent
* inode number go before direntry nodes with higher parent inode number,
* and direntry nodes with lower name hash values go before direntry nodes
* with higher name hash values.
*
* This function returns zero in case of success and a negative error code in
* case of failure.
*/
static int sort_nodes(struct ubifs_info *c, struct ubifs_scan_leb *sleb,
struct list_head *nondata, int *min)
{
int err;
struct ubifs_scan_node *snod, *tmp;
*min = INT_MAX;
/* Separate data nodes and non-data nodes */
list_for_each_entry_safe(snod, tmp, &sleb->nodes, list) {
ubifs_assert(snod->type == UBIFS_INO_NODE ||
snod->type == UBIFS_DATA_NODE ||
snod->type == UBIFS_DENT_NODE ||
snod->type == UBIFS_XENT_NODE ||
snod->type == UBIFS_TRUN_NODE);
if (snod->type != UBIFS_INO_NODE &&
snod->type != UBIFS_DATA_NODE &&
snod->type != UBIFS_DENT_NODE &&
snod->type != UBIFS_XENT_NODE) {
/* Probably truncation node, zap it */
list_del(&snod->list);
kfree(snod);
continue;
}
ubifs_assert(key_type(c, &snod->key) == UBIFS_DATA_KEY ||
key_type(c, &snod->key) == UBIFS_INO_KEY ||
key_type(c, &snod->key) == UBIFS_DENT_KEY ||
key_type(c, &snod->key) == UBIFS_XENT_KEY);
err = ubifs_tnc_has_node(c, &snod->key, 0, sleb->lnum,
snod->offs, 0);
if (err < 0)
return err;
if (!err) {
/* The node is obsolete, remove it from the list */
list_del(&snod->list);
kfree(snod);
continue;
}
if (snod->len < *min)
*min = snod->len;
if (key_type(c, &snod->key) != UBIFS_DATA_KEY)
list_move_tail(&snod->list, nondata);
}
/* Sort data and non-data nodes */
list_sort(c, &sleb->nodes, &data_nodes_cmp);
list_sort(c, nondata, &nondata_nodes_cmp);
err = dbg_check_data_nodes_order(c, &sleb->nodes);
if (err)
return err;
err = dbg_check_nondata_nodes_order(c, nondata);
if (err)
return err;
return 0;
}
/**
* move_node - move a node.
* @c: UBIFS file-system description object
* @sleb: describes the LEB to move nodes from
* @snod: the mode to move
* @wbuf: write-buffer to move node to
*
* This function moves node @snod to @wbuf, changes TNC correspondingly, and
* destroys @snod. Returns zero in case of success and a negative error code in
* case of failure.
*/
static int move_node(struct ubifs_info *c, struct ubifs_scan_leb *sleb,
struct ubifs_scan_node *snod, struct ubifs_wbuf *wbuf)
{
int err, new_lnum = wbuf->lnum, new_offs = wbuf->offs + wbuf->used;
cond_resched();
err = ubifs_wbuf_write_nolock(wbuf, snod->node, snod->len);
if (err)
return err;
err = ubifs_tnc_replace(c, &snod->key, sleb->lnum,
snod->offs, new_lnum, new_offs,
snod->len);
list_del(&snod->list);
kfree(snod);
return err;
}
/**
* move_nodes - move nodes.
* @c: UBIFS file-system description object
* @sleb: describes the LEB to move nodes from
*
* This function moves valid nodes from data LEB described by @sleb to the GC
* journal head. This function returns zero in case of success, %-EAGAIN if
* commit is required, and other negative error codes in case of other
* failures.
*/
static int move_nodes(struct ubifs_info *c, struct ubifs_scan_leb *sleb)
{
int err, min;
LIST_HEAD(nondata);
struct ubifs_wbuf *wbuf = &c->jheads[GCHD].wbuf;
if (wbuf->lnum == -1) {
/*
* The GC journal head is not set, because it is the first GC
* invocation since mount.
*/
err = switch_gc_head(c);
if (err)
return err;
}
err = sort_nodes(c, sleb, &nondata, &min);
if (err)
goto out;
/* Write nodes to their new location. Use the first-fit strategy */
while (1) {
int avail;
struct ubifs_scan_node *snod, *tmp;
/* Move data nodes */
list_for_each_entry_safe(snod, tmp, &sleb->nodes, list) {
avail = c->leb_size - wbuf->offs - wbuf->used;
if (snod->len > avail)
/*
* Do not skip data nodes in order to optimize
* bulk-read.
*/
break;
err = move_node(c, sleb, snod, wbuf);
if (err)
goto out;
}
/* Move non-data nodes */
list_for_each_entry_safe(snod, tmp, &nondata, list) {
avail = c->leb_size - wbuf->offs - wbuf->used;
if (avail < min)
break;
if (snod->len > avail) {
/*
* Keep going only if this is an inode with
* some data. Otherwise stop and switch the GC
* head. IOW, we assume that data-less inode
* nodes and direntry nodes are roughly of the
* same size.
*/
if (key_type(c, &snod->key) == UBIFS_DENT_KEY ||
snod->len == UBIFS_INO_NODE_SZ)
break;
continue;
}
err = move_node(c, sleb, snod, wbuf);
if (err)
goto out;
}
if (list_empty(&sleb->nodes) && list_empty(&nondata))
break;
/*
* Waste the rest of the space in the LEB and switch to the
* next LEB.
*/
err = switch_gc_head(c);
if (err)
goto out;
}
return 0;
out:
list_splice_tail(&nondata, &sleb->nodes);
return err;
}
/**
* gc_sync_wbufs - sync write-buffers for GC.
* @c: UBIFS file-system description object
*
* We must guarantee that obsoleting nodes are on flash. Unfortunately they may
* be in a write-buffer instead. That is, a node could be written to a
* write-buffer, obsoleting another node in a LEB that is GC'd. If that LEB is
* erased before the write-buffer is sync'd and then there is an unclean
* unmount, then an existing node is lost. To avoid this, we sync all
* write-buffers.
*
* This function returns %0 on success or a negative error code on failure.
*/
static int gc_sync_wbufs(struct ubifs_info *c)
{
int err, i;
for (i = 0; i < c->jhead_cnt; i++) {
if (i == GCHD)
continue;
err = ubifs_wbuf_sync(&c->jheads[i].wbuf);
if (err)
return err;
}
return 0;
}
/**
* ubifs_garbage_collect_leb - garbage-collect a logical eraseblock.
* @c: UBIFS file-system description object
* @lp: describes the LEB to garbage collect
*
* This function garbage-collects an LEB and returns one of the @LEB_FREED,
* @LEB_RETAINED, etc positive codes in case of success, %-EAGAIN if commit is
* required, and other negative error codes in case of failures.
*/
int ubifs_garbage_collect_leb(struct ubifs_info *c, struct ubifs_lprops *lp)
{
struct ubifs_scan_leb *sleb;
struct ubifs_scan_node *snod;
struct ubifs_wbuf *wbuf = &c->jheads[GCHD].wbuf;
int err = 0, lnum = lp->lnum;
ubifs_assert(c->gc_lnum != -1 || wbuf->offs + wbuf->used == 0 ||
c->need_recovery);
ubifs_assert(c->gc_lnum != lnum);
ubifs_assert(wbuf->lnum != lnum);
/*
* 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(!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(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->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(!wbuf->used);
for (i = 0; ; i++) {
int space_before = c->leb_size - wbuf->offs - wbuf->used;
int 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);
if (lp.free + lp.dirty == c->leb_size) {
/* An empty LEB was returned */
dbg_gc("LEB %d is free, return it", lp.lnum);
/*
* ubifs_find_dirty_leb() doesn't return freeable index
* LEBs.
*/
ubifs_assert(!(lp.flags & LPROPS_INDEX));
if (lp.free != c->leb_size) {
/*
* Write buffers must be sync'd before
* unmapping freeable LEBs, because one of them
* may contain data which obsoletes something
* in 'lp.pnum'.
*/
ret = gc_sync_wbufs(c);
if (ret)
goto out;
ret = ubifs_change_one_lp(c, lp.lnum,
c->leb_size, 0, 0, 0,
0);
if (ret)
goto out;
}
ret = ubifs_leb_unmap(c, lp.lnum);
if (ret)
goto out;
ret = lp.lnum;
break;
}
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(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(ret < 0);
ubifs_assert(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 (IS_ERR(lp)) {
err = PTR_ERR(lp);
goto out;
}
if (!lp)
break;
ubifs_assert(!(lp->flags & LPROPS_TAKEN));
ubifs_assert(!(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(!(lp->flags & LPROPS_TAKEN));
ubifs_assert(!(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(!(lp->flags & LPROPS_TAKEN));
ubifs_assert(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(lp->flags & LPROPS_TAKEN);
ubifs_assert(!(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;
}