linux/fs/ubifs/gc.c

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/*
* 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 view. The other LEBs are not so
* good, and GC takes extra care when moving them.
*/
include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h percpu.h is included by sched.h and module.h and thus ends up being included when building most .c files. percpu.h includes slab.h which in turn includes gfp.h making everything defined by the two files universally available and complicating inclusion dependencies. percpu.h -> slab.h dependency is about to be removed. Prepare for this change by updating users of gfp and slab facilities include those headers directly instead of assuming availability. As this conversion needs to touch large number of source files, the following script is used as the basis of conversion. http://userweb.kernel.org/~tj/misc/slabh-sweep.py The script does the followings. * Scan files for gfp and slab usages and update includes such that only the necessary includes are there. ie. if only gfp is used, gfp.h, if slab is used, slab.h. * When the script inserts a new include, it looks at the include blocks and try to put the new include such that its order conforms to its surrounding. It's put in the include block which contains core kernel includes, in the same order that the rest are ordered - alphabetical, Christmas tree, rev-Xmas-tree or at the end if there doesn't seem to be any matching order. * If the script can't find a place to put a new include (mostly because the file doesn't have fitting include block), it prints out an error message indicating which .h file needs to be added to the file. The conversion was done in the following steps. 1. The initial automatic conversion of all .c files updated slightly over 4000 files, deleting around 700 includes and adding ~480 gfp.h and ~3000 slab.h inclusions. The script emitted errors for ~400 files. 2. Each error was manually checked. Some didn't need the inclusion, some needed manual addition while adding it to implementation .h or embedding .c file was more appropriate for others. This step added inclusions to around 150 files. 3. The script was run again and the output was compared to the edits from #2 to make sure no file was left behind. 4. Several build tests were done and a couple of problems were fixed. e.g. lib/decompress_*.c used malloc/free() wrappers around slab APIs requiring slab.h to be added manually. 5. The script was run on all .h files but without automatically editing them as sprinkling gfp.h and slab.h inclusions around .h files could easily lead to inclusion dependency hell. Most gfp.h inclusion directives were ignored as stuff from gfp.h was usually wildly available and often used in preprocessor macros. Each slab.h inclusion directive was examined and added manually as necessary. 6. percpu.h was updated not to include slab.h. 7. Build test were done on the following configurations and failures were fixed. CONFIG_GCOV_KERNEL was turned off for all tests (as my distributed build env didn't work with gcov compiles) and a few more options had to be turned off depending on archs to make things build (like ipr on powerpc/64 which failed due to missing writeq). * x86 and x86_64 UP and SMP allmodconfig and a custom test config. * powerpc and powerpc64 SMP allmodconfig * sparc and sparc64 SMP allmodconfig * ia64 SMP allmodconfig * s390 SMP allmodconfig * alpha SMP allmodconfig * um on x86_64 SMP allmodconfig 8. percpu.h modifications were reverted so that it could be applied as a separate patch and serve as bisection point. Given the fact that I had only a couple of failures from tests on step 6, I'm fairly confident about the coverage of this conversion patch. If there is a breakage, it's likely to be something in one of the arch headers which should be easily discoverable easily on most builds of the specific arch. Signed-off-by: Tejun Heo <tj@kernel.org> Guess-its-ok-by: Christoph Lameter <cl@linux-foundation.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com>
2010-03-24 08:04:11 +00:00
#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(c, 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);
return err;
}
/**
* data_nodes_cmp - compare 2 data nodes.
* @priv: UBIFS file-system description object
* @a: first data node
* @b: second data node
*
* This function compares data nodes @a and @b. Returns %1 if @a has greater
* inode or block number, and %-1 otherwise.
*/
static 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(c, key_type(c, &sa->key) == UBIFS_DATA_KEY);
ubifs_assert(c, key_type(c, &sb->key) == UBIFS_DATA_KEY);
ubifs_assert(c, sa->type == UBIFS_DATA_NODE);
ubifs_assert(c, 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.
*/
static 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(c, key_type(c, &sa->key) != UBIFS_DATA_KEY &&
key_type(c, &sb->key) != UBIFS_DATA_KEY);
ubifs_assert(c, 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(c, key_type(c, &sa->key) == UBIFS_DENT_KEY ||
key_type(c, &sa->key) == UBIFS_XENT_KEY);
ubifs_assert(c, key_type(c, &sb->key) == UBIFS_DENT_KEY ||
key_type(c, &sb->key) == UBIFS_XENT_KEY);
ubifs_assert(c, sa->type == UBIFS_DENT_NODE ||
sa->type == UBIFS_XENT_NODE);
ubifs_assert(c, 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(c, snod->type == UBIFS_INO_NODE ||
snod->type == UBIFS_DATA_NODE ||
snod->type == UBIFS_DENT_NODE ||
snod->type == UBIFS_XENT_NODE ||
ubifs: Add authentication nodes to journal Nodes that are written to flash can only be authenticated through the index after the next commit. When a journal replay is necessary the nodes are not yet referenced by the index and thus can't be authenticated. This patch overcomes this situation by creating a hash over all nodes beginning from the commit start node over the reference node(s) and the buds themselves. From time to time we insert authentication nodes. Authentication nodes contain a HMAC from the current hash state, so that they can be used to authenticate a journal replay up to the point where the authentication node is. The hash is continued afterwards so that theoretically we would only have to check the HMAC of the last authentication node we find. Overall we get this picture: ,,,,,,,, ,......,........................................... ,. CS , hash1.----. hash2.----. ,. | , . |hmac . |hmac ,. v , . v . v ,.REF#0,-> bud -> bud -> bud.-> auth -> bud -> bud.-> auth ... ,..|...,........................................... , | , , | ,,,,,,,,,,,,,,, . | hash3,----. , | , |hmac , v , v , REF#1 -> bud -> bud,-> auth ... ,,,|,,,,,,,,,,,,,,,,,, v REF#2 -> ... | V ... Note how hash3 covers CS, REF#0 and REF#1 so that it is not possible to exchange or skip any reference nodes. Unlike the picture suggests the auth nodes themselves are not hashed. With this it is possible for an offline attacker to cut each journal head or to drop the last reference node(s), but not to skip any journal heads or to reorder any operations. Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de> Signed-off-by: Richard Weinberger <richard@nod.at>
2018-09-07 12:36:36 +00:00
snod->type == UBIFS_TRUN_NODE ||
snod->type == UBIFS_AUTH_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(c, 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, moved = 0;
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 -
ubifs_auth_node_sz(c);
if (snod->len > avail)
/*
* Do not skip data nodes in order to optimize
* bulk-read.
*/
break;
err = ubifs_shash_update(c, c->jheads[GCHD].log_hash,
snod->node, snod->len);
if (err)
goto out;
err = move_node(c, sleb, snod, wbuf);
if (err)
goto out;
moved = 1;
}
/* Move non-data nodes */
list_for_each_entry_safe(snod, tmp, &nondata, list) {
avail = c->leb_size - wbuf->offs - wbuf->used -
ubifs_auth_node_sz(c);
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 = ubifs_shash_update(c, c->jheads[GCHD].log_hash,
snod->node, snod->len);
if (err)
goto out;
err = move_node(c, sleb, snod, wbuf);
if (err)
goto out;
moved = 1;
}
if (ubifs_authenticated(c) && moved) {
struct ubifs_auth_node *auth;
auth = kmalloc(ubifs_auth_node_sz(c), GFP_NOFS);
if (!auth) {
err = -ENOMEM;
goto out;
}
err = ubifs_prepare_auth_node(c, auth,
c->jheads[GCHD].log_hash);
if (err) {
kfree(auth);
goto out;
}
err = ubifs_wbuf_write_nolock(wbuf, auth,
ubifs_auth_node_sz(c));
if (err) {
kfree(auth);
goto out;
}
ubifs_add_dirt(c, wbuf->lnum, ubifs_auth_node_sz(c));
}
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, c->gc_lnum != -1 || wbuf->offs + wbuf->used == 0 ||
c->need_recovery);
ubifs_assert(c, c->gc_lnum != lnum);
ubifs_assert(c, wbuf->lnum != lnum);
if (lp->free + lp->dirty == c->leb_size) {
/* Special case - a free LEB */
dbg_gc("LEB %d is free, return it", lp->lnum);
ubifs_assert(c, !(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->lnum'.
*/
err = gc_sync_wbufs(c);
if (err)
return err;
err = ubifs_change_one_lp(c, lp->lnum, c->leb_size,
0, 0, 0, 0);
if (err)
return err;
}
err = ubifs_leb_unmap(c, lp->lnum);
if (err)
return err;
if (c->gc_lnum == -1) {
c->gc_lnum = lnum;
return LEB_RETAINED;
}
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;
}