- 根目录:
- fs
- ubifs
- commit.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 functions that manage the running of the commit process.
* Each affected module has its own functions to accomplish their part in the
* commit and those functions are called here.
*
* The commit is the process whereby all updates to the index and LEB properties
* are written out together and the journal becomes empty. This keeps the
* file system consistent - at all times the state can be recreated by reading
* the index and LEB properties and then replaying the journal.
*
* The commit is split into two parts named "commit start" and "commit end".
* During commit start, the commit process has exclusive access to the journal
* by holding the commit semaphore down for writing. As few I/O operations as
* possible are performed during commit start, instead the nodes that are to be
* written are merely identified. During commit end, the commit semaphore is no
* longer held and the journal is again in operation, allowing users to continue
* to use the file system while the bulk of the commit I/O is performed. The
* purpose of this two-step approach is to prevent the commit from causing any
* latency blips. Note that in any case, the commit does not prevent lookups
* (as permitted by the TNC mutex), or access to VFS data structures e.g. page
* cache.
*/
#include <linux/freezer.h>
#include <linux/kthread.h>
#include <linux/slab.h>
#include "ubifs.h"
/*
* nothing_to_commit - check if there is nothing to commit.
* @c: UBIFS file-system description object
*
* This is a helper function which checks if there is anything to commit. It is
* used as an optimization to avoid starting the commit if it is not really
* necessary. Indeed, the commit operation always assumes flash I/O (e.g.,
* writing the commit start node to the log), and it is better to avoid doing
* this unnecessarily. E.g., 'ubifs_sync_fs()' runs the commit, but if there is
* nothing to commit, it is more optimal to avoid any flash I/O.
*
* This function has to be called with @c->commit_sem locked for writing -
* this function does not take LPT/TNC locks because the @c->commit_sem
* guarantees that we have exclusive access to the TNC and LPT data structures.
*
* This function returns %1 if there is nothing to commit and %0 otherwise.
*/
static int nothing_to_commit(struct ubifs_info *c)
{
/*
* During mounting or remounting from R/O mode to R/W mode we may
* commit for various recovery-related reasons.
*/
if (c->mounting || c->remounting_rw)
return 0;
/*
* If the root TNC node is dirty, we definitely have something to
* commit.
*/
if (c->zroot.znode && ubifs_zn_dirty(c->zroot.znode))
return 0;
/*
* Even though the TNC is clean, the LPT tree may have dirty nodes. For
* example, this may happen if the budgeting subsystem invoked GC to
* make some free space, and the GC found an LEB with only dirty and
* free space. In this case GC would just change the lprops of this
* LEB (by turning all space into free space) and unmap it.
*/
if (c->nroot && test_bit(DIRTY_CNODE, &c->nroot->flags))
return 0;
ubifs_assert(atomic_long_read(&c->dirty_zn_cnt) == 0);
ubifs_assert(c->dirty_pn_cnt == 0);
ubifs_assert(c->dirty_nn_cnt == 0);
return 1;
}
/**
* do_commit - commit the journal.
* @c: UBIFS file-system description object
*
* This function implements UBIFS commit. It has to be called with commit lock
* locked. Returns zero in case of success and a negative error code in case of
* failure.
*/
static int do_commit(struct ubifs_info *c)
{
int err, new_ltail_lnum, old_ltail_lnum, i;
struct ubifs_zbranch zroot;
struct ubifs_lp_stats lst;
dbg_cmt("start");
ubifs_assert(!c->ro_media && !c->ro_mount);
if (c->ro_error) {
err = -EROFS;
goto out_up;
}
if (nothing_to_commit(c)) {
up_write(&c->commit_sem);
err = 0;
goto out_cancel;
}
/* Sync all write buffers (necessary for recovery) */
for (i = 0; i < c->jhead_cnt; i++) {
err = ubifs_wbuf_sync(&c->jheads[i].wbuf);
if (err)
goto out_up;
}
c->cmt_no += 1;
err = ubifs_gc_start_commit(c);
if (err)
goto out_up;
err = dbg_check_lprops(c);
if (err)
goto out_up;
err = ubifs_log_start_commit(c, &new_ltail_lnum);
if (err)
goto out_up;
err = ubifs_tnc_start_commit(c, &zroot);
if (err)
goto out_up;
err = ubifs_lpt_start_commit(c);
if (err)
goto out_up;
err = ubifs_orphan_start_commit(c);
if (err)
goto out_up;
ubifs_get_lp_stats(c, &lst);
up_write(&c->commit_sem);
err = ubifs_tnc_end_commit(c);
if (err)
goto out;
err = ubifs_lpt_end_commit(c);
if (err)
goto out;
err = ubifs_orphan_end_commit(c);
if (err)
goto out;
err = dbg_check_old_index(c, &zroot);
if (err)
goto out;
c->mst_node->cmt_no = cpu_to_le64(c->cmt_no);
c->mst_node->log_lnum = cpu_to_le32(new_ltail_lnum);
c->mst_node->root_lnum = cpu_to_le32(zroot.lnum);
c->mst_node->root_offs = cpu_to_le32(zroot.offs);
c->mst_node->root_len = cpu_to_le32(zroot.len);
c->mst_node->ihead_lnum = cpu_to_le32(c->ihead_lnum);
c->mst_node->ihead_offs = cpu_to_le32(c->ihead_offs);
c->mst_node->index_size = cpu_to_le64(c->bi.old_idx_sz);
c->mst_node->lpt_lnum = cpu_to_le32(c->lpt_lnum);
c->mst_node->lpt_offs = cpu_to_le32(c->lpt_offs);
c->mst_node->nhead_lnum = cpu_to_le32(c->nhead_lnum);
c->mst_node->nhead_offs = cpu_to_le32(c->nhead_offs);
c->mst_node->ltab_lnum = cpu_to_le32(c->ltab_lnum);
c->mst_node->ltab_offs = cpu_to_le32(c->ltab_offs);
c->mst_node->lsave_lnum = cpu_to_le32(c->lsave_lnum);
c->mst_node->lsave_offs = cpu_to_le32(c->lsave_offs);
c->mst_node->lscan_lnum = cpu_to_le32(c->lscan_lnum);
c->mst_node->empty_lebs = cpu_to_le32(lst.empty_lebs);
c->mst_node->idx_lebs = cpu_to_le32(lst.idx_lebs);
c->mst_node->total_free = cpu_to_le64(lst.total_free);
c->mst_node->total_dirty = cpu_to_le64(lst.total_dirty);
c->mst_node->total_used = cpu_to_le64(lst.total_used);
c->mst_node->total_dead = cpu_to_le64(lst.total_dead);
c->mst_node->total_dark = cpu_to_le64(lst.total_dark);
if (c->no_orphs)
c->mst_node->flags |= cpu_to_le32(UBIFS_MST_NO_ORPHS);
else
c->mst_node->flags &= ~cpu_to_le32(UBIFS_MST_NO_ORPHS);
old_ltail_lnum = c->ltail_lnum;
err = ubifs_log_end_commit(c, new_ltail_lnum);
if (err)
goto out;
err = ubifs_log_post_commit(c, old_ltail_lnum);
if (err)
goto out;
err = ubifs_gc_end_commit(c);
if (err)
goto out;
err = ubifs_lpt_post_commit(c);
if (err)
goto out;
out_cancel:
spin_lock(&c->cs_lock);
c->cmt_state = COMMIT_RESTING;
wake_up(&c->cmt_wq);
dbg_cmt("commit end");
spin_unlock(&c->cs_lock);
return 0;
out_up:
up_write(&c->commit_sem);
out:
ubifs_err(c, "commit failed, error %d", err);
spin_lock(&c->cs_lock);
c->cmt_state = COMMIT_BROKEN;
wake_up(&c->cmt_wq);
spin_unlock(&c->cs_lock);
ubifs_ro_mode(c, err);
return err;
}
/**
* run_bg_commit - run background commit if it is needed.
* @c: UBIFS file-system description object
*
* This function runs background commit if it is needed. Returns zero in case
* of success and a negative error code in case of failure.
*/
static int run_bg_commit(struct ubifs_info *c)
{
spin_lock(&c->cs_lock);
/*
* Run background commit only if background commit was requested or if
* commit is required.
*/
if (c->cmt_state != COMMIT_BACKGROUND &&
c->cmt_state != COMMIT_REQUIRED)
goto out;
spin_unlock(&c->cs_lock);
down_write(&c->commit_sem);
spin_lock(&c->cs_lock);
if (c->cmt_state == COMMIT_REQUIRED)
c->cmt_state = COMMIT_RUNNING_REQUIRED;
else if (c->cmt_state == COMMIT_BACKGROUND)
c->cmt_state = COMMIT_RUNNING_BACKGROUND;
else
goto out_cmt_unlock;
spin_unlock(&c->cs_lock);
return do_commit(c);
out_cmt_unlock:
up_write(&c->commit_sem);
out:
spin_unlock(&c->cs_lock);
return 0;
}
/**
* ubifs_bg_thread - UBIFS background thread function.
* @info: points to the file-system description object
*
* This function implements various file-system background activities:
* o when a write-buffer timer expires it synchronizes the appropriate
* write-buffer;
* o when the journal is about to be full, it starts in-advance commit.
*
* Note, other stuff like background garbage collection may be added here in
* future.
*/
int ubifs_bg_thread(void *info)
{
int err;
struct ubifs_info *c = info;
ubifs_msg(c, "background thread \"%s\" started, PID %d",
c->bgt_name, current->pid);
set_freezable();
while (1) {
if (kthread_should_stop())
break;
if (try_to_freeze())
continue;
set_current_state(TASK_INTERRUPTIBLE);
/* Check if there is something to do */
if (!c->need_bgt) {
/*
* Nothing prevents us from going sleep now and
* be never woken up and block the task which
* could wait in 'kthread_stop()' forever.
*/
if (kthread_should_stop())
break;
schedule();
continue;
} else
__set_current_state(TASK_RUNNING);
c->need_bgt = 0;
err = ubifs_bg_wbufs_sync(c);
if (err)
ubifs_ro_mode(c, err);
run_bg_commit(c);
cond_resched();
}
ubifs_msg(c, "background thread \"%s\" stops", c->bgt_name);
return 0;
}
/**
* ubifs_commit_required - set commit state to "required".
* @c: UBIFS file-system description object
*
* This function is called if a commit is required but cannot be done from the
* calling function, so it is just flagged instead.
*/
void ubifs_commit_required(struct ubifs_info *c)
{
spin_lock(&c->cs_lock);
switch (c->cmt_state) {
case COMMIT_RESTING:
case COMMIT_BACKGROUND:
dbg_cmt("old: %s, new: %s", dbg_cstate(c->cmt_state),
dbg_cstate(COMMIT_REQUIRED));
c->cmt_state = COMMIT_REQUIRED;
break;
case COMMIT_RUNNING_BACKGROUND:
dbg_cmt("old: %s, new: %s", dbg_cstate(c->cmt_state),
dbg_cstate(COMMIT_RUNNING_REQUIRED));
c->cmt_state = COMMIT_RUNNING_REQUIRED;
break;
case COMMIT_REQUIRED:
case COMMIT_RUNNING_REQUIRED:
case COMMIT_BROKEN:
break;
}
spin_unlock(&c->cs_lock);
}
/**
* ubifs_request_bg_commit - notify the background thread to do a commit.
* @c: UBIFS file-system description object
*
* This function is called if the journal is full enough to make a commit
* worthwhile, so background thread is kicked to start it.
*/
void ubifs_request_bg_commit(struct ubifs_info *c)
{
spin_lock(&c->cs_lock);
if (c->cmt_state == COMMIT_RESTING) {
dbg_cmt("old: %s, new: %s", dbg_cstate(c->cmt_state),
dbg_cstate(COMMIT_BACKGROUND));
c->cmt_state = COMMIT_BACKGROUND;
spin_unlock(&c->cs_lock);
ubifs_wake_up_bgt(c);
} else
spin_unlock(&c->cs_lock);
}
/**
* wait_for_commit - wait for commit.
* @c: UBIFS file-system description object
*
* This function sleeps until the commit operation is no longer running.
*/
static int wait_for_commit(struct ubifs_info *c)
{
dbg_cmt("pid %d goes sleep", current->pid);
/*
* The following sleeps if the condition is false, and will be woken
* when the commit ends. It is possible, although very unlikely, that we
* will wake up and see the subsequent commit running, rather than the
* one we were waiting for, and go back to sleep. However, we will be
* woken again, so there is no danger of sleeping forever.
*/
wait_event(c->cmt_wq, c->cmt_state != COMMIT_RUNNING_BACKGROUND &&
c->cmt_state != COMMIT_RUNNING_REQUIRED);
dbg_cmt("commit finished, pid %d woke up", current->pid);
return 0;
}
/**
* ubifs_run_commit - run or wait for commit.
* @c: UBIFS file-system description object
*
* This function runs commit and returns zero in case of success and a negative
* error code in case of failure.
*/
int ubifs_run_commit(struct ubifs_info *c)
{
int err = 0;
spin_lock(&c->cs_lock);
if (c->cmt_state == COMMIT_BROKEN) {
err = -EROFS;
goto out;
}
if (c->cmt_state == COMMIT_RUNNING_BACKGROUND)
/*
* We set the commit state to 'running required' to indicate
* that we want it to complete as quickly as possible.
*/
c->cmt_state = COMMIT_RUNNING_REQUIRED;
if (c->cmt_state == COMMIT_RUNNING_REQUIRED) {
spin_unlock(&c->cs_lock);
return wait_for_commit(c);
}
spin_unlock(&c->cs_lock);
/* Ok, the commit is indeed needed */
down_write(&c->commit_sem);
spin_lock(&c->cs_lock);
/*
* Since we unlocked 'c->cs_lock', the state may have changed, so
* re-check it.
*/
if (c->cmt_state == COMMIT_BROKEN) {
err = -EROFS;
goto out_cmt_unlock;
}
if (c->cmt_state == COMMIT_RUNNING_BACKGROUND)
c->cmt_state = COMMIT_RUNNING_REQUIRED;
if (c->cmt_state == COMMIT_RUNNING_REQUIRED) {
up_write(&c->commit_sem);
spin_unlock(&c->cs_lock);
return wait_for_commit(c);
}
c->cmt_state = COMMIT_RUNNING_REQUIRED;
spin_unlock(&c->cs_lock);
err = do_commit(c);
return err;
out_cmt_unlock:
up_write(&c->commit_sem);
out:
spin_unlock(&c->cs_lock);
return err;
}
/**
* ubifs_gc_should_commit - determine if it is time for GC to run commit.
* @c: UBIFS file-system description object
*
* This function is called by garbage collection to determine if commit should
* be run. If commit state is @COMMIT_BACKGROUND, which means that the journal
* is full enough to start commit, this function returns true. It is not
* absolutely necessary to commit yet, but it feels like this should be better
* then to keep doing GC. This function returns %1 if GC has to initiate commit
* and %0 if not.
*/
int ubifs_gc_should_commit(struct ubifs_info *c)
{
int ret = 0;
spin_lock(&c->cs_lock);
if (c->cmt_state == COMMIT_BACKGROUND) {
dbg_cmt("commit required now");
c->cmt_state = COMMIT_REQUIRED;
} else
dbg_cmt("commit not requested");
if (c->cmt_state == COMMIT_REQUIRED)
ret = 1;
spin_unlock(&c->cs_lock);
return ret;
}
/*
* Everything below is related to debugging.
*/
/**
* struct idx_node - hold index nodes during index tree traversal.
* @list: list
* @iip: index in parent (slot number of this indexing node in the parent
* indexing node)
* @upper_key: all keys in this indexing node have to be less or equivalent to
* this key
* @idx: index node (8-byte aligned because all node structures must be 8-byte
* aligned)
*/
struct idx_node {
struct list_head list;
int iip;
union ubifs_key upper_key;
struct ubifs_idx_node idx __aligned(8);
};
/**
* dbg_old_index_check_init - get information for the next old index check.
* @c: UBIFS file-system description object
* @zroot: root of the index
*
* This function records information about the index that will be needed for the
* next old index check i.e. 'dbg_check_old_index()'.
*
* This function returns %0 on success and a negative error code on failure.
*/
int dbg_old_index_check_init(struct ubifs_info *c, struct ubifs_zbranch *zroot)
{
struct ubifs_idx_node *idx;
int lnum, offs, len, err = 0;
struct ubifs_debug_info *d = c->dbg;
d->old_zroot = *zroot;
lnum = d->old_zroot.lnum;
offs = d->old_zroot.offs;
len = d->old_zroot.len;
idx = kmalloc(c->max_idx_node_sz, GFP_NOFS);
if (!idx)
return -ENOMEM;
err = ubifs_read_node(c, idx, UBIFS_IDX_NODE, len, lnum, offs);
if (err)
goto out;
d->old_zroot_level = le16_to_cpu(idx->level);
d->old_zroot_sqnum = le64_to_cpu(idx->ch.sqnum);
out:
kfree(idx);
return err;
}
/**
* dbg_check_old_index - check the old copy of the index.
* @c: UBIFS file-system description object
* @zroot: root of the new index
*
* In order to be able to recover from an unclean unmount, a complete copy of
* the index must exist on flash. This is the "old" index. The commit process
* must write the "new" index to flash without overwriting or destroying any
* part of the old index. This function is run at commit end in order to check
* that the old index does indeed exist completely intact.
*
* This function returns %0 on success and a negative error code on failure.
*/
int dbg_check_old_index(struct ubifs_info *c, struct ubifs_zbranch *zroot)
{
int lnum, offs, len, err = 0, uninitialized_var(last_level), child_cnt;
int first = 1, iip;
struct ubifs_debug_info *d = c->dbg;
union ubifs_key uninitialized_var(lower_key), upper_key, l_key, u_key;
unsigned long long uninitialized_var(last_sqnum);
struct ubifs_idx_node *idx;
struct list_head list;
struct idx_node *i;
size_t sz;
if (!dbg_is_chk_index(c))
return 0;
INIT_LIST_HEAD(&list);
sz = sizeof(struct idx_node) + ubifs_idx_node_sz(c, c->fanout) -
UBIFS_IDX_NODE_SZ;
/* Start at the old zroot */
lnum = d->old_zroot.lnum;
offs = d->old_zroot.offs;
len = d->old_zroot.len;
iip = 0;
/*
* Traverse the index tree preorder depth-first i.e. do a node and then
* its subtrees from left to right.
*/
while (1) {
struct ubifs_branch *br;
/* Get the next index node */
i = kmalloc(sz, GFP_NOFS);
if (!i) {
err = -ENOMEM;
goto out_free;
}
i->iip = iip;
/* Keep the index nodes on our path in a linked list */
list_add_tail(&i->list, &list);
/* Read the index node */
idx = &i->idx;
err = ubifs_read_node(c, idx, UBIFS_IDX_NODE, len, lnum, offs);
if (err)
goto out_free;
/* Validate index node */
child_cnt = le16_to_cpu(idx->child_cnt);
if (child_cnt < 1 || child_cnt > c->fanout) {
err = 1;
goto out_dump;
}
if (first) {
first = 0;
/* Check root level and sqnum */
if (le16_to_cpu(idx->level) != d->old_zroot_level) {
err = 2;
goto out_dump;
}
if (le64_to_cpu(idx->ch.sqnum) != d->old_zroot_sqnum) {
err = 3;
goto out_dump;
}
/* Set last values as though root had a parent */
last_level = le16_to_cpu(idx->level) + 1;
last_sqnum = le64_to_cpu(idx->ch.sqnum) + 1;
key_read(c, ubifs_idx_key(c, idx), &lower_key);
highest_ino_key(c, &upper_key, INUM_WATERMARK);
}
key_copy(c, &upper_key, &i->upper_key);
if (le16_to_cpu(idx->level) != last_level - 1) {
err = 3;
goto out_dump;
}
/*
* The index is always written bottom up hence a child's sqnum
* is always less than the parents.
*/
if (le64_to_cpu(idx->ch.sqnum) >= last_sqnum) {
err = 4;
goto out_dump;
}
/* Check key range */
key_read(c, ubifs_idx_key(c, idx), &l_key);
br = ubifs_idx_branch(c, idx, child_cnt - 1);
key_read(c, &br->key, &u_key);
if (keys_cmp(c, &lower_key, &l_key) > 0) {
err = 5;
goto out_dump;
}
if (keys_cmp(c, &upper_key, &u_key) < 0) {
err = 6;
goto out_dump;
}
if (keys_cmp(c, &upper_key, &u_key) == 0)
if (!is_hash_key(c, &u_key)) {
err = 7;
goto out_dump;
}
/* Go to next index node */
if (le16_to_cpu(idx->level) == 0) {
/* At the bottom, so go up until can go right */
while (1) {
/* Drop the bottom of the list */
list_del(&i->list);
kfree(i);
/* No more list means we are done */
if (list_empty(&list))
goto out;
/* Look at the new bottom */
i = list_entry(list.prev, struct idx_node,
list);
idx = &i->idx;
/* Can we go right */
if (iip + 1 < le16_to_cpu(idx->child_cnt)) {
iip = iip + 1;
break;
} else
/* Nope, so go up again */
iip = i->iip;
}
} else
/* Go down left */
iip = 0;
/*
* We have the parent in 'idx' and now we set up for reading the
* child pointed to by slot 'iip'.
*/
last_level = le16_to_cpu(idx->level);
last_sqnum = le64_to_cpu(idx->ch.sqnum);
br = ubifs_idx_branch(c, idx, iip);
lnum = le32_to_cpu(br->lnum);
offs = le32_to_cpu(br->offs);
len = le32_to_cpu(br->len);
key_read(c, &br->key, &lower_key);
if (iip + 1 < le16_to_cpu(idx->child_cnt)) {
br = ubifs_idx_branch(c, idx, iip + 1);
key_read(c, &br->key, &upper_key);
} else
key_copy(c, &i->upper_key, &upper_key);
}
out:
err = dbg_old_index_check_init(c, zroot);
if (err)
goto out_free;
return 0;
out_dump:
ubifs_err(c, "dumping index node (iip=%d)", i->iip);
ubifs_dump_node(c, idx);
list_del(&i->list);
kfree(i);
if (!list_empty(&list)) {
i = list_entry(list.prev, struct idx_node, list);
ubifs_err(c, "dumping parent index node");
ubifs_dump_node(c, &i->idx);
}
out_free:
while (!list_empty(&list)) {
i = list_entry(list.next, struct idx_node, list);
list_del(&i->list);
kfree(i);
}
ubifs_err(c, "failed, error %d", err);
if (err > 0)
err = -EINVAL;
return err;
}