linux/fs/jbd/checkpoint.c

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/*
* linux/fs/jbd/checkpoint.c
*
* Written by Stephen C. Tweedie <sct@redhat.com>, 1999
*
* Copyright 1999 Red Hat Software --- All Rights Reserved
*
* This file is part of the Linux kernel and is made available under
* the terms of the GNU General Public License, version 2, or at your
* option, any later version, incorporated herein by reference.
*
* Checkpoint routines for the generic filesystem journaling code.
* Part of the ext2fs journaling system.
*
* Checkpointing is the process of ensuring that a section of the log is
* committed fully to disk, so that that portion of the log can be
* reused.
*/
#include <linux/time.h>
#include <linux/fs.h>
#include <linux/jbd.h>
#include <linux/errno.h>
#include <linux/slab.h>
#include <linux/blkdev.h>
#include <trace/events/jbd.h>
/*
* Unlink a buffer from a transaction checkpoint list.
*
* Called with j_list_lock held.
*/
static inline void __buffer_unlink_first(struct journal_head *jh)
{
transaction_t *transaction = jh->b_cp_transaction;
jh->b_cpnext->b_cpprev = jh->b_cpprev;
jh->b_cpprev->b_cpnext = jh->b_cpnext;
if (transaction->t_checkpoint_list == jh) {
transaction->t_checkpoint_list = jh->b_cpnext;
if (transaction->t_checkpoint_list == jh)
transaction->t_checkpoint_list = NULL;
}
}
/*
* Unlink a buffer from a transaction checkpoint(io) list.
*
* Called with j_list_lock held.
*/
static inline void __buffer_unlink(struct journal_head *jh)
{
transaction_t *transaction = jh->b_cp_transaction;
__buffer_unlink_first(jh);
if (transaction->t_checkpoint_io_list == jh) {
transaction->t_checkpoint_io_list = jh->b_cpnext;
if (transaction->t_checkpoint_io_list == jh)
transaction->t_checkpoint_io_list = NULL;
}
}
/*
* Move a buffer from the checkpoint list to the checkpoint io list
*
* Called with j_list_lock held
*/
static inline void __buffer_relink_io(struct journal_head *jh)
{
transaction_t *transaction = jh->b_cp_transaction;
__buffer_unlink_first(jh);
if (!transaction->t_checkpoint_io_list) {
jh->b_cpnext = jh->b_cpprev = jh;
} else {
jh->b_cpnext = transaction->t_checkpoint_io_list;
jh->b_cpprev = transaction->t_checkpoint_io_list->b_cpprev;
jh->b_cpprev->b_cpnext = jh;
jh->b_cpnext->b_cpprev = jh;
}
transaction->t_checkpoint_io_list = jh;
}
/*
* Try to release a checkpointed buffer from its transaction.
* Returns 1 if we released it and 2 if we also released the
* whole transaction.
*
* Requires j_list_lock
* Called under jbd_lock_bh_state(jh2bh(jh)), and drops it
*/
static int __try_to_free_cp_buf(struct journal_head *jh)
{
int ret = 0;
struct buffer_head *bh = jh2bh(jh);
jbd: fix error handling for checkpoint io When a checkpointing IO fails, current JBD code doesn't check the error and continue journaling. This means latest metadata can be lost from both the journal and filesystem. This patch leaves the failed metadata blocks in the journal space and aborts journaling in the case of log_do_checkpoint(). To achieve this, we need to do: 1. don't remove the failed buffer from the checkpoint list where in the case of __try_to_free_cp_buf() because it may be released or overwritten by a later transaction 2. log_do_checkpoint() is the last chance, remove the failed buffer from the checkpoint list and abort the journal 3. when checkpointing fails, don't update the journal super block to prevent the journaled contents from being cleaned. For safety, don't update j_tail and j_tail_sequence either 4. when checkpointing fails, notify this error to the ext3 layer so that ext3 don't clear the needs_recovery flag, otherwise the journaled contents are ignored and cleaned in the recovery phase 5. if the recovery fails, keep the needs_recovery flag 6. prevent cleanup_journal_tail() from being called between __journal_drop_transaction() and journal_abort() (a race issue between journal_flush() and __log_wait_for_space() Signed-off-by: Hidehiro Kawai <hidehiro.kawai.ez@hitachi.com> Acked-by: Jan Kara <jack@suse.cz> Cc: <linux-ext4@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-10-22 21:15:00 +00:00
if (jh->b_jlist == BJ_None && !buffer_locked(bh) &&
!buffer_dirty(bh) && !buffer_write_io_error(bh)) {
jbd: Fix oops in journal_remove_journal_head() journal_remove_journal_head() can oops when trying to access journal_head returned by bh2jh(). This is caused for example by the following race: TASK1 TASK2 journal_commit_transaction() ... processing t_forget list __journal_refile_buffer(jh); if (!jh->b_transaction) { jbd_unlock_bh_state(bh); journal_try_to_free_buffers() journal_grab_journal_head(bh) jbd_lock_bh_state(bh) __journal_try_to_free_buffer() journal_put_journal_head(jh) journal_remove_journal_head(bh); journal_put_journal_head() in TASK2 sees that b_jcount == 0 and buffer is not part of any transaction and thus frees journal_head before TASK1 gets to doing so. Note that even buffer_head can be released by try_to_free_buffers() after journal_put_journal_head() which adds even larger opportunity for oops (but I didn't see this happen in reality). Fix the problem by making transactions hold their own journal_head reference (in b_jcount). That way we don't have to remove journal_head explicitely via journal_remove_journal_head() and instead just remove journal_head when b_jcount drops to zero. The result of this is that [__]journal_refile_buffer(), [__]journal_unfile_buffer(), and __journal_remove_checkpoint() can free journal_head which needs modification of a few callers. Also we have to be careful because once journal_head is removed, buffer_head might be freed as well. So we have to get our own buffer_head reference where it matters. Signed-off-by: Jan Kara <jack@suse.cz>
2011-06-24 21:11:59 +00:00
/*
* Get our reference so that bh cannot be freed before
* we unlock it
*/
get_bh(bh);
JBUFFER_TRACE(jh, "remove from checkpoint list");
ret = __journal_remove_checkpoint(jh) + 1;
jbd_unlock_bh_state(bh);
BUFFER_TRACE(bh, "release");
__brelse(bh);
} else {
jbd_unlock_bh_state(bh);
}
return ret;
}
/*
* __log_wait_for_space: wait until there is space in the journal.
*
* Called under j-state_lock *only*. It will be unlocked if we have to wait
* for a checkpoint to free up some space in the log.
*/
void __log_wait_for_space(journal_t *journal)
{
int nblocks, space_left;
assert_spin_locked(&journal->j_state_lock);
nblocks = jbd_space_needed(journal);
while (__log_space_left(journal) < nblocks) {
if (journal->j_flags & JFS_ABORT)
return;
spin_unlock(&journal->j_state_lock);
mutex_lock(&journal->j_checkpoint_mutex);
/*
* Test again, another process may have checkpointed while we
* were waiting for the checkpoint lock. If there are no
* transactions ready to be checkpointed, try to recover
* journal space by calling cleanup_journal_tail(), and if
* that doesn't work, by waiting for the currently committing
* transaction to complete. If there is absolutely no way
* to make progress, this is either a BUG or corrupted
* filesystem, so abort the journal and leave a stack
* trace for forensic evidence.
*/
spin_lock(&journal->j_state_lock);
spin_lock(&journal->j_list_lock);
nblocks = jbd_space_needed(journal);
space_left = __log_space_left(journal);
if (space_left < nblocks) {
int chkpt = journal->j_checkpoint_transactions != NULL;
tid_t tid = 0;
if (journal->j_committing_transaction)
tid = journal->j_committing_transaction->t_tid;
spin_unlock(&journal->j_list_lock);
spin_unlock(&journal->j_state_lock);
if (chkpt) {
log_do_checkpoint(journal);
} else if (cleanup_journal_tail(journal) == 0) {
/* We were able to recover space; yay! */
;
} else if (tid) {
log_wait_commit(journal, tid);
} else {
printk(KERN_ERR "%s: needed %d blocks and "
"only had %d space available\n",
__func__, nblocks, space_left);
printk(KERN_ERR "%s: no way to get more "
"journal space\n", __func__);
WARN_ON(1);
journal_abort(journal, 0);
}
spin_lock(&journal->j_state_lock);
} else {
spin_unlock(&journal->j_list_lock);
}
mutex_unlock(&journal->j_checkpoint_mutex);
}
}
/*
* We were unable to perform jbd_trylock_bh_state() inside j_list_lock.
* The caller must restart a list walk. Wait for someone else to run
* jbd_unlock_bh_state().
*/
static void jbd_sync_bh(journal_t *journal, struct buffer_head *bh)
__releases(journal->j_list_lock)
{
get_bh(bh);
spin_unlock(&journal->j_list_lock);
jbd_lock_bh_state(bh);
jbd_unlock_bh_state(bh);
put_bh(bh);
}
/*
* Clean up transaction's list of buffers submitted for io.
* We wait for any pending IO to complete and remove any clean
* buffers. Note that we take the buffers in the opposite ordering
* from the one in which they were submitted for IO.
*
jbd: fix error handling for checkpoint io When a checkpointing IO fails, current JBD code doesn't check the error and continue journaling. This means latest metadata can be lost from both the journal and filesystem. This patch leaves the failed metadata blocks in the journal space and aborts journaling in the case of log_do_checkpoint(). To achieve this, we need to do: 1. don't remove the failed buffer from the checkpoint list where in the case of __try_to_free_cp_buf() because it may be released or overwritten by a later transaction 2. log_do_checkpoint() is the last chance, remove the failed buffer from the checkpoint list and abort the journal 3. when checkpointing fails, don't update the journal super block to prevent the journaled contents from being cleaned. For safety, don't update j_tail and j_tail_sequence either 4. when checkpointing fails, notify this error to the ext3 layer so that ext3 don't clear the needs_recovery flag, otherwise the journaled contents are ignored and cleaned in the recovery phase 5. if the recovery fails, keep the needs_recovery flag 6. prevent cleanup_journal_tail() from being called between __journal_drop_transaction() and journal_abort() (a race issue between journal_flush() and __log_wait_for_space() Signed-off-by: Hidehiro Kawai <hidehiro.kawai.ez@hitachi.com> Acked-by: Jan Kara <jack@suse.cz> Cc: <linux-ext4@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-10-22 21:15:00 +00:00
* Return 0 on success, and return <0 if some buffers have failed
* to be written out.
*
* Called with j_list_lock held.
*/
jbd: fix error handling for checkpoint io When a checkpointing IO fails, current JBD code doesn't check the error and continue journaling. This means latest metadata can be lost from both the journal and filesystem. This patch leaves the failed metadata blocks in the journal space and aborts journaling in the case of log_do_checkpoint(). To achieve this, we need to do: 1. don't remove the failed buffer from the checkpoint list where in the case of __try_to_free_cp_buf() because it may be released or overwritten by a later transaction 2. log_do_checkpoint() is the last chance, remove the failed buffer from the checkpoint list and abort the journal 3. when checkpointing fails, don't update the journal super block to prevent the journaled contents from being cleaned. For safety, don't update j_tail and j_tail_sequence either 4. when checkpointing fails, notify this error to the ext3 layer so that ext3 don't clear the needs_recovery flag, otherwise the journaled contents are ignored and cleaned in the recovery phase 5. if the recovery fails, keep the needs_recovery flag 6. prevent cleanup_journal_tail() from being called between __journal_drop_transaction() and journal_abort() (a race issue between journal_flush() and __log_wait_for_space() Signed-off-by: Hidehiro Kawai <hidehiro.kawai.ez@hitachi.com> Acked-by: Jan Kara <jack@suse.cz> Cc: <linux-ext4@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-10-22 21:15:00 +00:00
static int __wait_cp_io(journal_t *journal, transaction_t *transaction)
{
struct journal_head *jh;
struct buffer_head *bh;
tid_t this_tid;
int released = 0;
jbd: fix error handling for checkpoint io When a checkpointing IO fails, current JBD code doesn't check the error and continue journaling. This means latest metadata can be lost from both the journal and filesystem. This patch leaves the failed metadata blocks in the journal space and aborts journaling in the case of log_do_checkpoint(). To achieve this, we need to do: 1. don't remove the failed buffer from the checkpoint list where in the case of __try_to_free_cp_buf() because it may be released or overwritten by a later transaction 2. log_do_checkpoint() is the last chance, remove the failed buffer from the checkpoint list and abort the journal 3. when checkpointing fails, don't update the journal super block to prevent the journaled contents from being cleaned. For safety, don't update j_tail and j_tail_sequence either 4. when checkpointing fails, notify this error to the ext3 layer so that ext3 don't clear the needs_recovery flag, otherwise the journaled contents are ignored and cleaned in the recovery phase 5. if the recovery fails, keep the needs_recovery flag 6. prevent cleanup_journal_tail() from being called between __journal_drop_transaction() and journal_abort() (a race issue between journal_flush() and __log_wait_for_space() Signed-off-by: Hidehiro Kawai <hidehiro.kawai.ez@hitachi.com> Acked-by: Jan Kara <jack@suse.cz> Cc: <linux-ext4@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-10-22 21:15:00 +00:00
int ret = 0;
this_tid = transaction->t_tid;
restart:
/* Did somebody clean up the transaction in the meanwhile? */
if (journal->j_checkpoint_transactions != transaction ||
transaction->t_tid != this_tid)
jbd: fix error handling for checkpoint io When a checkpointing IO fails, current JBD code doesn't check the error and continue journaling. This means latest metadata can be lost from both the journal and filesystem. This patch leaves the failed metadata blocks in the journal space and aborts journaling in the case of log_do_checkpoint(). To achieve this, we need to do: 1. don't remove the failed buffer from the checkpoint list where in the case of __try_to_free_cp_buf() because it may be released or overwritten by a later transaction 2. log_do_checkpoint() is the last chance, remove the failed buffer from the checkpoint list and abort the journal 3. when checkpointing fails, don't update the journal super block to prevent the journaled contents from being cleaned. For safety, don't update j_tail and j_tail_sequence either 4. when checkpointing fails, notify this error to the ext3 layer so that ext3 don't clear the needs_recovery flag, otherwise the journaled contents are ignored and cleaned in the recovery phase 5. if the recovery fails, keep the needs_recovery flag 6. prevent cleanup_journal_tail() from being called between __journal_drop_transaction() and journal_abort() (a race issue between journal_flush() and __log_wait_for_space() Signed-off-by: Hidehiro Kawai <hidehiro.kawai.ez@hitachi.com> Acked-by: Jan Kara <jack@suse.cz> Cc: <linux-ext4@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-10-22 21:15:00 +00:00
return ret;
while (!released && transaction->t_checkpoint_io_list) {
jh = transaction->t_checkpoint_io_list;
bh = jh2bh(jh);
if (!jbd_trylock_bh_state(bh)) {
jbd_sync_bh(journal, bh);
spin_lock(&journal->j_list_lock);
goto restart;
}
jbd: Fix oops in journal_remove_journal_head() journal_remove_journal_head() can oops when trying to access journal_head returned by bh2jh(). This is caused for example by the following race: TASK1 TASK2 journal_commit_transaction() ... processing t_forget list __journal_refile_buffer(jh); if (!jh->b_transaction) { jbd_unlock_bh_state(bh); journal_try_to_free_buffers() journal_grab_journal_head(bh) jbd_lock_bh_state(bh) __journal_try_to_free_buffer() journal_put_journal_head(jh) journal_remove_journal_head(bh); journal_put_journal_head() in TASK2 sees that b_jcount == 0 and buffer is not part of any transaction and thus frees journal_head before TASK1 gets to doing so. Note that even buffer_head can be released by try_to_free_buffers() after journal_put_journal_head() which adds even larger opportunity for oops (but I didn't see this happen in reality). Fix the problem by making transactions hold their own journal_head reference (in b_jcount). That way we don't have to remove journal_head explicitely via journal_remove_journal_head() and instead just remove journal_head when b_jcount drops to zero. The result of this is that [__]journal_refile_buffer(), [__]journal_unfile_buffer(), and __journal_remove_checkpoint() can free journal_head which needs modification of a few callers. Also we have to be careful because once journal_head is removed, buffer_head might be freed as well. So we have to get our own buffer_head reference where it matters. Signed-off-by: Jan Kara <jack@suse.cz>
2011-06-24 21:11:59 +00:00
get_bh(bh);
if (buffer_locked(bh)) {
spin_unlock(&journal->j_list_lock);
jbd_unlock_bh_state(bh);
wait_on_buffer(bh);
/* the journal_head may have gone by now */
BUFFER_TRACE(bh, "brelse");
__brelse(bh);
spin_lock(&journal->j_list_lock);
goto restart;
}
if (unlikely(buffer_write_io_error(bh)))
jbd: fix error handling for checkpoint io When a checkpointing IO fails, current JBD code doesn't check the error and continue journaling. This means latest metadata can be lost from both the journal and filesystem. This patch leaves the failed metadata blocks in the journal space and aborts journaling in the case of log_do_checkpoint(). To achieve this, we need to do: 1. don't remove the failed buffer from the checkpoint list where in the case of __try_to_free_cp_buf() because it may be released or overwritten by a later transaction 2. log_do_checkpoint() is the last chance, remove the failed buffer from the checkpoint list and abort the journal 3. when checkpointing fails, don't update the journal super block to prevent the journaled contents from being cleaned. For safety, don't update j_tail and j_tail_sequence either 4. when checkpointing fails, notify this error to the ext3 layer so that ext3 don't clear the needs_recovery flag, otherwise the journaled contents are ignored and cleaned in the recovery phase 5. if the recovery fails, keep the needs_recovery flag 6. prevent cleanup_journal_tail() from being called between __journal_drop_transaction() and journal_abort() (a race issue between journal_flush() and __log_wait_for_space() Signed-off-by: Hidehiro Kawai <hidehiro.kawai.ez@hitachi.com> Acked-by: Jan Kara <jack@suse.cz> Cc: <linux-ext4@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-10-22 21:15:00 +00:00
ret = -EIO;
/*
* Now in whatever state the buffer currently is, we know that
* it has been written out and so we can drop it from the list
*/
released = __journal_remove_checkpoint(jh);
jbd_unlock_bh_state(bh);
__brelse(bh);
}
jbd: fix error handling for checkpoint io When a checkpointing IO fails, current JBD code doesn't check the error and continue journaling. This means latest metadata can be lost from both the journal and filesystem. This patch leaves the failed metadata blocks in the journal space and aborts journaling in the case of log_do_checkpoint(). To achieve this, we need to do: 1. don't remove the failed buffer from the checkpoint list where in the case of __try_to_free_cp_buf() because it may be released or overwritten by a later transaction 2. log_do_checkpoint() is the last chance, remove the failed buffer from the checkpoint list and abort the journal 3. when checkpointing fails, don't update the journal super block to prevent the journaled contents from being cleaned. For safety, don't update j_tail and j_tail_sequence either 4. when checkpointing fails, notify this error to the ext3 layer so that ext3 don't clear the needs_recovery flag, otherwise the journaled contents are ignored and cleaned in the recovery phase 5. if the recovery fails, keep the needs_recovery flag 6. prevent cleanup_journal_tail() from being called between __journal_drop_transaction() and journal_abort() (a race issue between journal_flush() and __log_wait_for_space() Signed-off-by: Hidehiro Kawai <hidehiro.kawai.ez@hitachi.com> Acked-by: Jan Kara <jack@suse.cz> Cc: <linux-ext4@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-10-22 21:15:00 +00:00
return ret;
}
#define NR_BATCH 64
static void
__flush_batch(journal_t *journal, struct buffer_head **bhs, int *batch_count)
{
int i;
struct blk_plug plug;
blk_start_plug(&plug);
for (i = 0; i < *batch_count; i++)
write_dirty_buffer(bhs[i], WRITE_SYNC);
blk_finish_plug(&plug);
for (i = 0; i < *batch_count; i++) {
struct buffer_head *bh = bhs[i];
clear_buffer_jwrite(bh);
BUFFER_TRACE(bh, "brelse");
__brelse(bh);
}
*batch_count = 0;
}
/*
* Try to flush one buffer from the checkpoint list to disk.
*
* Return 1 if something happened which requires us to abort the current
jbd: fix error handling for checkpoint io When a checkpointing IO fails, current JBD code doesn't check the error and continue journaling. This means latest metadata can be lost from both the journal and filesystem. This patch leaves the failed metadata blocks in the journal space and aborts journaling in the case of log_do_checkpoint(). To achieve this, we need to do: 1. don't remove the failed buffer from the checkpoint list where in the case of __try_to_free_cp_buf() because it may be released or overwritten by a later transaction 2. log_do_checkpoint() is the last chance, remove the failed buffer from the checkpoint list and abort the journal 3. when checkpointing fails, don't update the journal super block to prevent the journaled contents from being cleaned. For safety, don't update j_tail and j_tail_sequence either 4. when checkpointing fails, notify this error to the ext3 layer so that ext3 don't clear the needs_recovery flag, otherwise the journaled contents are ignored and cleaned in the recovery phase 5. if the recovery fails, keep the needs_recovery flag 6. prevent cleanup_journal_tail() from being called between __journal_drop_transaction() and journal_abort() (a race issue between journal_flush() and __log_wait_for_space() Signed-off-by: Hidehiro Kawai <hidehiro.kawai.ez@hitachi.com> Acked-by: Jan Kara <jack@suse.cz> Cc: <linux-ext4@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-10-22 21:15:00 +00:00
* scan of the checkpoint list. Return <0 if the buffer has failed to
* be written out.
*
* Called with j_list_lock held and drops it if 1 is returned
* Called under jbd_lock_bh_state(jh2bh(jh)), and drops it
*/
static int __process_buffer(journal_t *journal, struct journal_head *jh,
struct buffer_head **bhs, int *batch_count)
{
struct buffer_head *bh = jh2bh(jh);
int ret = 0;
if (buffer_locked(bh)) {
get_bh(bh);
spin_unlock(&journal->j_list_lock);
jbd_unlock_bh_state(bh);
wait_on_buffer(bh);
/* the journal_head may have gone by now */
BUFFER_TRACE(bh, "brelse");
__brelse(bh);
ret = 1;
} else if (jh->b_transaction != NULL) {
transaction_t *t = jh->b_transaction;
tid_t tid = t->t_tid;
spin_unlock(&journal->j_list_lock);
jbd_unlock_bh_state(bh);
log_start_commit(journal, tid);
log_wait_commit(journal, tid);
ret = 1;
} else if (!buffer_dirty(bh)) {
jbd: fix error handling for checkpoint io When a checkpointing IO fails, current JBD code doesn't check the error and continue journaling. This means latest metadata can be lost from both the journal and filesystem. This patch leaves the failed metadata blocks in the journal space and aborts journaling in the case of log_do_checkpoint(). To achieve this, we need to do: 1. don't remove the failed buffer from the checkpoint list where in the case of __try_to_free_cp_buf() because it may be released or overwritten by a later transaction 2. log_do_checkpoint() is the last chance, remove the failed buffer from the checkpoint list and abort the journal 3. when checkpointing fails, don't update the journal super block to prevent the journaled contents from being cleaned. For safety, don't update j_tail and j_tail_sequence either 4. when checkpointing fails, notify this error to the ext3 layer so that ext3 don't clear the needs_recovery flag, otherwise the journaled contents are ignored and cleaned in the recovery phase 5. if the recovery fails, keep the needs_recovery flag 6. prevent cleanup_journal_tail() from being called between __journal_drop_transaction() and journal_abort() (a race issue between journal_flush() and __log_wait_for_space() Signed-off-by: Hidehiro Kawai <hidehiro.kawai.ez@hitachi.com> Acked-by: Jan Kara <jack@suse.cz> Cc: <linux-ext4@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-10-22 21:15:00 +00:00
ret = 1;
if (unlikely(buffer_write_io_error(bh)))
jbd: fix error handling for checkpoint io When a checkpointing IO fails, current JBD code doesn't check the error and continue journaling. This means latest metadata can be lost from both the journal and filesystem. This patch leaves the failed metadata blocks in the journal space and aborts journaling in the case of log_do_checkpoint(). To achieve this, we need to do: 1. don't remove the failed buffer from the checkpoint list where in the case of __try_to_free_cp_buf() because it may be released or overwritten by a later transaction 2. log_do_checkpoint() is the last chance, remove the failed buffer from the checkpoint list and abort the journal 3. when checkpointing fails, don't update the journal super block to prevent the journaled contents from being cleaned. For safety, don't update j_tail and j_tail_sequence either 4. when checkpointing fails, notify this error to the ext3 layer so that ext3 don't clear the needs_recovery flag, otherwise the journaled contents are ignored and cleaned in the recovery phase 5. if the recovery fails, keep the needs_recovery flag 6. prevent cleanup_journal_tail() from being called between __journal_drop_transaction() and journal_abort() (a race issue between journal_flush() and __log_wait_for_space() Signed-off-by: Hidehiro Kawai <hidehiro.kawai.ez@hitachi.com> Acked-by: Jan Kara <jack@suse.cz> Cc: <linux-ext4@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-10-22 21:15:00 +00:00
ret = -EIO;
jbd: Fix oops in journal_remove_journal_head() journal_remove_journal_head() can oops when trying to access journal_head returned by bh2jh(). This is caused for example by the following race: TASK1 TASK2 journal_commit_transaction() ... processing t_forget list __journal_refile_buffer(jh); if (!jh->b_transaction) { jbd_unlock_bh_state(bh); journal_try_to_free_buffers() journal_grab_journal_head(bh) jbd_lock_bh_state(bh) __journal_try_to_free_buffer() journal_put_journal_head(jh) journal_remove_journal_head(bh); journal_put_journal_head() in TASK2 sees that b_jcount == 0 and buffer is not part of any transaction and thus frees journal_head before TASK1 gets to doing so. Note that even buffer_head can be released by try_to_free_buffers() after journal_put_journal_head() which adds even larger opportunity for oops (but I didn't see this happen in reality). Fix the problem by making transactions hold their own journal_head reference (in b_jcount). That way we don't have to remove journal_head explicitely via journal_remove_journal_head() and instead just remove journal_head when b_jcount drops to zero. The result of this is that [__]journal_refile_buffer(), [__]journal_unfile_buffer(), and __journal_remove_checkpoint() can free journal_head which needs modification of a few callers. Also we have to be careful because once journal_head is removed, buffer_head might be freed as well. So we have to get our own buffer_head reference where it matters. Signed-off-by: Jan Kara <jack@suse.cz>
2011-06-24 21:11:59 +00:00
get_bh(bh);
J_ASSERT_JH(jh, !buffer_jbddirty(bh));
BUFFER_TRACE(bh, "remove from checkpoint");
__journal_remove_checkpoint(jh);
spin_unlock(&journal->j_list_lock);
jbd_unlock_bh_state(bh);
__brelse(bh);
} else {
/*
* Important: we are about to write the buffer, and
* possibly block, while still holding the journal lock.
* We cannot afford to let the transaction logic start
* messing around with this buffer before we write it to
* disk, as that would break recoverability.
*/
BUFFER_TRACE(bh, "queue");
get_bh(bh);
J_ASSERT_BH(bh, !buffer_jwrite(bh));
set_buffer_jwrite(bh);
bhs[*batch_count] = bh;
__buffer_relink_io(jh);
jbd_unlock_bh_state(bh);
(*batch_count)++;
if (*batch_count == NR_BATCH) {
spin_unlock(&journal->j_list_lock);
__flush_batch(journal, bhs, batch_count);
ret = 1;
}
}
return ret;
}
/*
* Perform an actual checkpoint. We take the first transaction on the
* list of transactions to be checkpointed and send all its buffers
* to disk. We submit larger chunks of data at once.
*
* The journal should be locked before calling this function.
jbd: fix error handling for checkpoint io When a checkpointing IO fails, current JBD code doesn't check the error and continue journaling. This means latest metadata can be lost from both the journal and filesystem. This patch leaves the failed metadata blocks in the journal space and aborts journaling in the case of log_do_checkpoint(). To achieve this, we need to do: 1. don't remove the failed buffer from the checkpoint list where in the case of __try_to_free_cp_buf() because it may be released or overwritten by a later transaction 2. log_do_checkpoint() is the last chance, remove the failed buffer from the checkpoint list and abort the journal 3. when checkpointing fails, don't update the journal super block to prevent the journaled contents from being cleaned. For safety, don't update j_tail and j_tail_sequence either 4. when checkpointing fails, notify this error to the ext3 layer so that ext3 don't clear the needs_recovery flag, otherwise the journaled contents are ignored and cleaned in the recovery phase 5. if the recovery fails, keep the needs_recovery flag 6. prevent cleanup_journal_tail() from being called between __journal_drop_transaction() and journal_abort() (a race issue between journal_flush() and __log_wait_for_space() Signed-off-by: Hidehiro Kawai <hidehiro.kawai.ez@hitachi.com> Acked-by: Jan Kara <jack@suse.cz> Cc: <linux-ext4@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-10-22 21:15:00 +00:00
* Called with j_checkpoint_mutex held.
*/
int log_do_checkpoint(journal_t *journal)
{
transaction_t *transaction;
tid_t this_tid;
int result;
jbd_debug(1, "Start checkpoint\n");
/*
* First thing: if there are any transactions in the log which
* don't need checkpointing, just eliminate them from the
* journal straight away.
*/
result = cleanup_journal_tail(journal);
trace_jbd_checkpoint(journal, result);
jbd_debug(1, "cleanup_journal_tail returned %d\n", result);
if (result <= 0)
return result;
/*
* OK, we need to start writing disk blocks. Take one transaction
* and write it.
*/
jbd: fix error handling for checkpoint io When a checkpointing IO fails, current JBD code doesn't check the error and continue journaling. This means latest metadata can be lost from both the journal and filesystem. This patch leaves the failed metadata blocks in the journal space and aborts journaling in the case of log_do_checkpoint(). To achieve this, we need to do: 1. don't remove the failed buffer from the checkpoint list where in the case of __try_to_free_cp_buf() because it may be released or overwritten by a later transaction 2. log_do_checkpoint() is the last chance, remove the failed buffer from the checkpoint list and abort the journal 3. when checkpointing fails, don't update the journal super block to prevent the journaled contents from being cleaned. For safety, don't update j_tail and j_tail_sequence either 4. when checkpointing fails, notify this error to the ext3 layer so that ext3 don't clear the needs_recovery flag, otherwise the journaled contents are ignored and cleaned in the recovery phase 5. if the recovery fails, keep the needs_recovery flag 6. prevent cleanup_journal_tail() from being called between __journal_drop_transaction() and journal_abort() (a race issue between journal_flush() and __log_wait_for_space() Signed-off-by: Hidehiro Kawai <hidehiro.kawai.ez@hitachi.com> Acked-by: Jan Kara <jack@suse.cz> Cc: <linux-ext4@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-10-22 21:15:00 +00:00
result = 0;
spin_lock(&journal->j_list_lock);
if (!journal->j_checkpoint_transactions)
goto out;
transaction = journal->j_checkpoint_transactions;
this_tid = transaction->t_tid;
restart:
/*
* If someone cleaned up this transaction while we slept, we're
* done (maybe it's a new transaction, but it fell at the same
* address).
*/
if (journal->j_checkpoint_transactions == transaction &&
transaction->t_tid == this_tid) {
int batch_count = 0;
struct buffer_head *bhs[NR_BATCH];
struct journal_head *jh;
jbd: fix error handling for checkpoint io When a checkpointing IO fails, current JBD code doesn't check the error and continue journaling. This means latest metadata can be lost from both the journal and filesystem. This patch leaves the failed metadata blocks in the journal space and aborts journaling in the case of log_do_checkpoint(). To achieve this, we need to do: 1. don't remove the failed buffer from the checkpoint list where in the case of __try_to_free_cp_buf() because it may be released or overwritten by a later transaction 2. log_do_checkpoint() is the last chance, remove the failed buffer from the checkpoint list and abort the journal 3. when checkpointing fails, don't update the journal super block to prevent the journaled contents from being cleaned. For safety, don't update j_tail and j_tail_sequence either 4. when checkpointing fails, notify this error to the ext3 layer so that ext3 don't clear the needs_recovery flag, otherwise the journaled contents are ignored and cleaned in the recovery phase 5. if the recovery fails, keep the needs_recovery flag 6. prevent cleanup_journal_tail() from being called between __journal_drop_transaction() and journal_abort() (a race issue between journal_flush() and __log_wait_for_space() Signed-off-by: Hidehiro Kawai <hidehiro.kawai.ez@hitachi.com> Acked-by: Jan Kara <jack@suse.cz> Cc: <linux-ext4@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-10-22 21:15:00 +00:00
int retry = 0, err;
while (!retry && transaction->t_checkpoint_list) {
struct buffer_head *bh;
jh = transaction->t_checkpoint_list;
bh = jh2bh(jh);
if (!jbd_trylock_bh_state(bh)) {
jbd_sync_bh(journal, bh);
retry = 1;
break;
}
retry = __process_buffer(journal, jh, bhs,&batch_count);
jbd: fix error handling for checkpoint io When a checkpointing IO fails, current JBD code doesn't check the error and continue journaling. This means latest metadata can be lost from both the journal and filesystem. This patch leaves the failed metadata blocks in the journal space and aborts journaling in the case of log_do_checkpoint(). To achieve this, we need to do: 1. don't remove the failed buffer from the checkpoint list where in the case of __try_to_free_cp_buf() because it may be released or overwritten by a later transaction 2. log_do_checkpoint() is the last chance, remove the failed buffer from the checkpoint list and abort the journal 3. when checkpointing fails, don't update the journal super block to prevent the journaled contents from being cleaned. For safety, don't update j_tail and j_tail_sequence either 4. when checkpointing fails, notify this error to the ext3 layer so that ext3 don't clear the needs_recovery flag, otherwise the journaled contents are ignored and cleaned in the recovery phase 5. if the recovery fails, keep the needs_recovery flag 6. prevent cleanup_journal_tail() from being called between __journal_drop_transaction() and journal_abort() (a race issue between journal_flush() and __log_wait_for_space() Signed-off-by: Hidehiro Kawai <hidehiro.kawai.ez@hitachi.com> Acked-by: Jan Kara <jack@suse.cz> Cc: <linux-ext4@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-10-22 21:15:00 +00:00
if (retry < 0 && !result)
result = retry;
if (!retry && (need_resched() ||
spin_needbreak(&journal->j_list_lock))) {
spin_unlock(&journal->j_list_lock);
retry = 1;
break;
}
}
if (batch_count) {
if (!retry) {
spin_unlock(&journal->j_list_lock);
retry = 1;
}
__flush_batch(journal, bhs, &batch_count);
}
if (retry) {
spin_lock(&journal->j_list_lock);
goto restart;
}
/*
* Now we have cleaned up the first transaction's checkpoint
* list. Let's clean up the second one
*/
jbd: fix error handling for checkpoint io When a checkpointing IO fails, current JBD code doesn't check the error and continue journaling. This means latest metadata can be lost from both the journal and filesystem. This patch leaves the failed metadata blocks in the journal space and aborts journaling in the case of log_do_checkpoint(). To achieve this, we need to do: 1. don't remove the failed buffer from the checkpoint list where in the case of __try_to_free_cp_buf() because it may be released or overwritten by a later transaction 2. log_do_checkpoint() is the last chance, remove the failed buffer from the checkpoint list and abort the journal 3. when checkpointing fails, don't update the journal super block to prevent the journaled contents from being cleaned. For safety, don't update j_tail and j_tail_sequence either 4. when checkpointing fails, notify this error to the ext3 layer so that ext3 don't clear the needs_recovery flag, otherwise the journaled contents are ignored and cleaned in the recovery phase 5. if the recovery fails, keep the needs_recovery flag 6. prevent cleanup_journal_tail() from being called between __journal_drop_transaction() and journal_abort() (a race issue between journal_flush() and __log_wait_for_space() Signed-off-by: Hidehiro Kawai <hidehiro.kawai.ez@hitachi.com> Acked-by: Jan Kara <jack@suse.cz> Cc: <linux-ext4@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-10-22 21:15:00 +00:00
err = __wait_cp_io(journal, transaction);
if (!result)
result = err;
}
out:
spin_unlock(&journal->j_list_lock);
if (result < 0)
jbd: fix error handling for checkpoint io When a checkpointing IO fails, current JBD code doesn't check the error and continue journaling. This means latest metadata can be lost from both the journal and filesystem. This patch leaves the failed metadata blocks in the journal space and aborts journaling in the case of log_do_checkpoint(). To achieve this, we need to do: 1. don't remove the failed buffer from the checkpoint list where in the case of __try_to_free_cp_buf() because it may be released or overwritten by a later transaction 2. log_do_checkpoint() is the last chance, remove the failed buffer from the checkpoint list and abort the journal 3. when checkpointing fails, don't update the journal super block to prevent the journaled contents from being cleaned. For safety, don't update j_tail and j_tail_sequence either 4. when checkpointing fails, notify this error to the ext3 layer so that ext3 don't clear the needs_recovery flag, otherwise the journaled contents are ignored and cleaned in the recovery phase 5. if the recovery fails, keep the needs_recovery flag 6. prevent cleanup_journal_tail() from being called between __journal_drop_transaction() and journal_abort() (a race issue between journal_flush() and __log_wait_for_space() Signed-off-by: Hidehiro Kawai <hidehiro.kawai.ez@hitachi.com> Acked-by: Jan Kara <jack@suse.cz> Cc: <linux-ext4@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-10-22 21:15:00 +00:00
journal_abort(journal, result);
else
result = cleanup_journal_tail(journal);
return (result < 0) ? result : 0;
}
/*
* Check the list of checkpoint transactions for the journal to see if
* we have already got rid of any since the last update of the log tail
* in the journal superblock. If so, we can instantly roll the
* superblock forward to remove those transactions from the log.
*
* Return <0 on error, 0 on success, 1 if there was nothing to clean up.
*
* This is the only part of the journaling code which really needs to be
* aware of transaction aborts. Checkpointing involves writing to the
* main filesystem area rather than to the journal, so it can proceed
jbd: fix error handling for checkpoint io When a checkpointing IO fails, current JBD code doesn't check the error and continue journaling. This means latest metadata can be lost from both the journal and filesystem. This patch leaves the failed metadata blocks in the journal space and aborts journaling in the case of log_do_checkpoint(). To achieve this, we need to do: 1. don't remove the failed buffer from the checkpoint list where in the case of __try_to_free_cp_buf() because it may be released or overwritten by a later transaction 2. log_do_checkpoint() is the last chance, remove the failed buffer from the checkpoint list and abort the journal 3. when checkpointing fails, don't update the journal super block to prevent the journaled contents from being cleaned. For safety, don't update j_tail and j_tail_sequence either 4. when checkpointing fails, notify this error to the ext3 layer so that ext3 don't clear the needs_recovery flag, otherwise the journaled contents are ignored and cleaned in the recovery phase 5. if the recovery fails, keep the needs_recovery flag 6. prevent cleanup_journal_tail() from being called between __journal_drop_transaction() and journal_abort() (a race issue between journal_flush() and __log_wait_for_space() Signed-off-by: Hidehiro Kawai <hidehiro.kawai.ez@hitachi.com> Acked-by: Jan Kara <jack@suse.cz> Cc: <linux-ext4@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-10-22 21:15:00 +00:00
* even in abort state, but we must not update the super block if
* checkpointing may have failed. Otherwise, we would lose some metadata
* buffers which should be written-back to the filesystem.
*/
int cleanup_journal_tail(journal_t *journal)
{
transaction_t * transaction;
tid_t first_tid;
unsigned int blocknr, freed;
jbd: fix error handling for checkpoint io When a checkpointing IO fails, current JBD code doesn't check the error and continue journaling. This means latest metadata can be lost from both the journal and filesystem. This patch leaves the failed metadata blocks in the journal space and aborts journaling in the case of log_do_checkpoint(). To achieve this, we need to do: 1. don't remove the failed buffer from the checkpoint list where in the case of __try_to_free_cp_buf() because it may be released or overwritten by a later transaction 2. log_do_checkpoint() is the last chance, remove the failed buffer from the checkpoint list and abort the journal 3. when checkpointing fails, don't update the journal super block to prevent the journaled contents from being cleaned. For safety, don't update j_tail and j_tail_sequence either 4. when checkpointing fails, notify this error to the ext3 layer so that ext3 don't clear the needs_recovery flag, otherwise the journaled contents are ignored and cleaned in the recovery phase 5. if the recovery fails, keep the needs_recovery flag 6. prevent cleanup_journal_tail() from being called between __journal_drop_transaction() and journal_abort() (a race issue between journal_flush() and __log_wait_for_space() Signed-off-by: Hidehiro Kawai <hidehiro.kawai.ez@hitachi.com> Acked-by: Jan Kara <jack@suse.cz> Cc: <linux-ext4@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-10-22 21:15:00 +00:00
if (is_journal_aborted(journal))
return 1;
/*
* OK, work out the oldest transaction remaining in the log, and
* the log block it starts at.
*
* If the log is now empty, we need to work out which is the
* next transaction ID we will write, and where it will
* start.
*/
spin_lock(&journal->j_state_lock);
spin_lock(&journal->j_list_lock);
transaction = journal->j_checkpoint_transactions;
if (transaction) {
first_tid = transaction->t_tid;
blocknr = transaction->t_log_start;
} else if ((transaction = journal->j_committing_transaction) != NULL) {
first_tid = transaction->t_tid;
blocknr = transaction->t_log_start;
} else if ((transaction = journal->j_running_transaction) != NULL) {
first_tid = transaction->t_tid;
blocknr = journal->j_head;
} else {
first_tid = journal->j_transaction_sequence;
blocknr = journal->j_head;
}
spin_unlock(&journal->j_list_lock);
J_ASSERT(blocknr != 0);
/* If the oldest pinned transaction is at the tail of the log
already then there's not much we can do right now. */
if (journal->j_tail_sequence == first_tid) {
spin_unlock(&journal->j_state_lock);
return 1;
}
spin_unlock(&journal->j_state_lock);
/*
* We need to make sure that any blocks that were recently written out
* --- perhaps by log_do_checkpoint() --- are flushed out before we
* drop the transactions from the journal. Similarly we need to be sure
* superblock makes it to disk before next transaction starts reusing
* freed space (otherwise we could replay some blocks of the new
* transaction thinking they belong to the old one). So we use
* WRITE_FLUSH_FUA. It's unlikely this will be necessary, especially
* with an appropriately sized journal, but we need this to guarantee
* correctness. Fortunately cleanup_journal_tail() doesn't get called
* all that often.
*/
journal_update_sb_log_tail(journal, first_tid, blocknr,
WRITE_FLUSH_FUA);
spin_lock(&journal->j_state_lock);
/* OK, update the superblock to recover the freed space.
* Physical blocks come first: have we wrapped beyond the end of
* the log? */
freed = blocknr - journal->j_tail;
if (blocknr < journal->j_tail)
freed = freed + journal->j_last - journal->j_first;
trace_jbd_cleanup_journal_tail(journal, first_tid, blocknr, freed);
jbd_debug(1,
"Cleaning journal tail from %d to %d (offset %u), "
"freeing %u\n",
journal->j_tail_sequence, first_tid, blocknr, freed);
journal->j_free += freed;
journal->j_tail_sequence = first_tid;
journal->j_tail = blocknr;
spin_unlock(&journal->j_state_lock);
return 0;
}
/* Checkpoint list management */
/*
* journal_clean_one_cp_list
*
jbd: Fix oops in journal_remove_journal_head() journal_remove_journal_head() can oops when trying to access journal_head returned by bh2jh(). This is caused for example by the following race: TASK1 TASK2 journal_commit_transaction() ... processing t_forget list __journal_refile_buffer(jh); if (!jh->b_transaction) { jbd_unlock_bh_state(bh); journal_try_to_free_buffers() journal_grab_journal_head(bh) jbd_lock_bh_state(bh) __journal_try_to_free_buffer() journal_put_journal_head(jh) journal_remove_journal_head(bh); journal_put_journal_head() in TASK2 sees that b_jcount == 0 and buffer is not part of any transaction and thus frees journal_head before TASK1 gets to doing so. Note that even buffer_head can be released by try_to_free_buffers() after journal_put_journal_head() which adds even larger opportunity for oops (but I didn't see this happen in reality). Fix the problem by making transactions hold their own journal_head reference (in b_jcount). That way we don't have to remove journal_head explicitely via journal_remove_journal_head() and instead just remove journal_head when b_jcount drops to zero. The result of this is that [__]journal_refile_buffer(), [__]journal_unfile_buffer(), and __journal_remove_checkpoint() can free journal_head which needs modification of a few callers. Also we have to be careful because once journal_head is removed, buffer_head might be freed as well. So we have to get our own buffer_head reference where it matters. Signed-off-by: Jan Kara <jack@suse.cz>
2011-06-24 21:11:59 +00:00
* Find all the written-back checkpoint buffers in the given list and release
* them.
*
* Called with j_list_lock held.
* Returns number of buffers reaped (for debug)
*/
static int journal_clean_one_cp_list(struct journal_head *jh, int *released)
{
struct journal_head *last_jh;
struct journal_head *next_jh = jh;
int ret, freed = 0;
*released = 0;
if (!jh)
return 0;
last_jh = jh->b_cpprev;
do {
jh = next_jh;
next_jh = jh->b_cpnext;
/* Use trylock because of the ranking */
if (jbd_trylock_bh_state(jh2bh(jh))) {
ret = __try_to_free_cp_buf(jh);
if (ret) {
freed++;
if (ret == 2) {
*released = 1;
return freed;
}
}
}
/*
* This function only frees up some memory
* if possible so we dont have an obligation
* to finish processing. Bail out if preemption
* requested:
*/
if (need_resched())
return freed;
} while (jh != last_jh);
return freed;
}
/*
* journal_clean_checkpoint_list
*
* Find all the written-back checkpoint buffers in the journal and release them.
*
* Called with the journal locked.
* Called with j_list_lock held.
* Returns number of buffers reaped (for debug)
*/
int __journal_clean_checkpoint_list(journal_t *journal)
{
transaction_t *transaction, *last_transaction, *next_transaction;
int ret = 0;
int released;
transaction = journal->j_checkpoint_transactions;
if (!transaction)
goto out;
last_transaction = transaction->t_cpprev;
next_transaction = transaction;
do {
transaction = next_transaction;
next_transaction = transaction->t_cpnext;
ret += journal_clean_one_cp_list(transaction->
t_checkpoint_list, &released);
/*
* This function only frees up some memory if possible so we
* dont have an obligation to finish processing. Bail out if
* preemption requested:
*/
if (need_resched())
goto out;
if (released)
continue;
/*
* It is essential that we are as careful as in the case of
* t_checkpoint_list with removing the buffer from the list as
* we can possibly see not yet submitted buffers on io_list
*/
ret += journal_clean_one_cp_list(transaction->
t_checkpoint_io_list, &released);
if (need_resched())
goto out;
} while (transaction != last_transaction);
out:
return ret;
}
/*
* journal_remove_checkpoint: called after a buffer has been committed
* to disk (either by being write-back flushed to disk, or being
* committed to the log).
*
* We cannot safely clean a transaction out of the log until all of the
* buffer updates committed in that transaction have safely been stored
* elsewhere on disk. To achieve this, all of the buffers in a
* transaction need to be maintained on the transaction's checkpoint
* lists until they have been rewritten, at which point this function is
* called to remove the buffer from the existing transaction's
* checkpoint lists.
*
* The function returns 1 if it frees the transaction, 0 otherwise.
jbd: Fix oops in journal_remove_journal_head() journal_remove_journal_head() can oops when trying to access journal_head returned by bh2jh(). This is caused for example by the following race: TASK1 TASK2 journal_commit_transaction() ... processing t_forget list __journal_refile_buffer(jh); if (!jh->b_transaction) { jbd_unlock_bh_state(bh); journal_try_to_free_buffers() journal_grab_journal_head(bh) jbd_lock_bh_state(bh) __journal_try_to_free_buffer() journal_put_journal_head(jh) journal_remove_journal_head(bh); journal_put_journal_head() in TASK2 sees that b_jcount == 0 and buffer is not part of any transaction and thus frees journal_head before TASK1 gets to doing so. Note that even buffer_head can be released by try_to_free_buffers() after journal_put_journal_head() which adds even larger opportunity for oops (but I didn't see this happen in reality). Fix the problem by making transactions hold their own journal_head reference (in b_jcount). That way we don't have to remove journal_head explicitely via journal_remove_journal_head() and instead just remove journal_head when b_jcount drops to zero. The result of this is that [__]journal_refile_buffer(), [__]journal_unfile_buffer(), and __journal_remove_checkpoint() can free journal_head which needs modification of a few callers. Also we have to be careful because once journal_head is removed, buffer_head might be freed as well. So we have to get our own buffer_head reference where it matters. Signed-off-by: Jan Kara <jack@suse.cz>
2011-06-24 21:11:59 +00:00
* The function can free jh and bh.
*
* This function is called with j_list_lock held.
* This function is called with jbd_lock_bh_state(jh2bh(jh))
*/
int __journal_remove_checkpoint(struct journal_head *jh)
{
transaction_t *transaction;
journal_t *journal;
int ret = 0;
JBUFFER_TRACE(jh, "entry");
if ((transaction = jh->b_cp_transaction) == NULL) {
JBUFFER_TRACE(jh, "not on transaction");
goto out;
}
journal = transaction->t_journal;
jbd: Fix oops in journal_remove_journal_head() journal_remove_journal_head() can oops when trying to access journal_head returned by bh2jh(). This is caused for example by the following race: TASK1 TASK2 journal_commit_transaction() ... processing t_forget list __journal_refile_buffer(jh); if (!jh->b_transaction) { jbd_unlock_bh_state(bh); journal_try_to_free_buffers() journal_grab_journal_head(bh) jbd_lock_bh_state(bh) __journal_try_to_free_buffer() journal_put_journal_head(jh) journal_remove_journal_head(bh); journal_put_journal_head() in TASK2 sees that b_jcount == 0 and buffer is not part of any transaction and thus frees journal_head before TASK1 gets to doing so. Note that even buffer_head can be released by try_to_free_buffers() after journal_put_journal_head() which adds even larger opportunity for oops (but I didn't see this happen in reality). Fix the problem by making transactions hold their own journal_head reference (in b_jcount). That way we don't have to remove journal_head explicitely via journal_remove_journal_head() and instead just remove journal_head when b_jcount drops to zero. The result of this is that [__]journal_refile_buffer(), [__]journal_unfile_buffer(), and __journal_remove_checkpoint() can free journal_head which needs modification of a few callers. Also we have to be careful because once journal_head is removed, buffer_head might be freed as well. So we have to get our own buffer_head reference where it matters. Signed-off-by: Jan Kara <jack@suse.cz>
2011-06-24 21:11:59 +00:00
JBUFFER_TRACE(jh, "removing from transaction");
__buffer_unlink(jh);
jh->b_cp_transaction = NULL;
jbd: Fix oops in journal_remove_journal_head() journal_remove_journal_head() can oops when trying to access journal_head returned by bh2jh(). This is caused for example by the following race: TASK1 TASK2 journal_commit_transaction() ... processing t_forget list __journal_refile_buffer(jh); if (!jh->b_transaction) { jbd_unlock_bh_state(bh); journal_try_to_free_buffers() journal_grab_journal_head(bh) jbd_lock_bh_state(bh) __journal_try_to_free_buffer() journal_put_journal_head(jh) journal_remove_journal_head(bh); journal_put_journal_head() in TASK2 sees that b_jcount == 0 and buffer is not part of any transaction and thus frees journal_head before TASK1 gets to doing so. Note that even buffer_head can be released by try_to_free_buffers() after journal_put_journal_head() which adds even larger opportunity for oops (but I didn't see this happen in reality). Fix the problem by making transactions hold their own journal_head reference (in b_jcount). That way we don't have to remove journal_head explicitely via journal_remove_journal_head() and instead just remove journal_head when b_jcount drops to zero. The result of this is that [__]journal_refile_buffer(), [__]journal_unfile_buffer(), and __journal_remove_checkpoint() can free journal_head which needs modification of a few callers. Also we have to be careful because once journal_head is removed, buffer_head might be freed as well. So we have to get our own buffer_head reference where it matters. Signed-off-by: Jan Kara <jack@suse.cz>
2011-06-24 21:11:59 +00:00
journal_put_journal_head(jh);
if (transaction->t_checkpoint_list != NULL ||
transaction->t_checkpoint_io_list != NULL)
goto out;
/*
* There is one special case to worry about: if we have just pulled the
* buffer off a running or committing transaction's checkpoing list,
* then even if the checkpoint list is empty, the transaction obviously
* cannot be dropped!
*
* The locking here around t_state is a bit sleazy.
* See the comment at the end of journal_commit_transaction().
*/
jbd: Fix oops in journal_remove_journal_head() journal_remove_journal_head() can oops when trying to access journal_head returned by bh2jh(). This is caused for example by the following race: TASK1 TASK2 journal_commit_transaction() ... processing t_forget list __journal_refile_buffer(jh); if (!jh->b_transaction) { jbd_unlock_bh_state(bh); journal_try_to_free_buffers() journal_grab_journal_head(bh) jbd_lock_bh_state(bh) __journal_try_to_free_buffer() journal_put_journal_head(jh) journal_remove_journal_head(bh); journal_put_journal_head() in TASK2 sees that b_jcount == 0 and buffer is not part of any transaction and thus frees journal_head before TASK1 gets to doing so. Note that even buffer_head can be released by try_to_free_buffers() after journal_put_journal_head() which adds even larger opportunity for oops (but I didn't see this happen in reality). Fix the problem by making transactions hold their own journal_head reference (in b_jcount). That way we don't have to remove journal_head explicitely via journal_remove_journal_head() and instead just remove journal_head when b_jcount drops to zero. The result of this is that [__]journal_refile_buffer(), [__]journal_unfile_buffer(), and __journal_remove_checkpoint() can free journal_head which needs modification of a few callers. Also we have to be careful because once journal_head is removed, buffer_head might be freed as well. So we have to get our own buffer_head reference where it matters. Signed-off-by: Jan Kara <jack@suse.cz>
2011-06-24 21:11:59 +00:00
if (transaction->t_state != T_FINISHED)
goto out;
/* OK, that was the last buffer for the transaction: we can now
safely remove this transaction from the log */
__journal_drop_transaction(journal, transaction);
/* Just in case anybody was waiting for more transactions to be
checkpointed... */
wake_up(&journal->j_wait_logspace);
ret = 1;
out:
return ret;
}
/*
* journal_insert_checkpoint: put a committed buffer onto a checkpoint
* list so that we know when it is safe to clean the transaction out of
* the log.
*
* Called with the journal locked.
* Called with j_list_lock held.
*/
void __journal_insert_checkpoint(struct journal_head *jh,
transaction_t *transaction)
{
JBUFFER_TRACE(jh, "entry");
J_ASSERT_JH(jh, buffer_dirty(jh2bh(jh)) || buffer_jbddirty(jh2bh(jh)));
J_ASSERT_JH(jh, jh->b_cp_transaction == NULL);
jbd: Fix oops in journal_remove_journal_head() journal_remove_journal_head() can oops when trying to access journal_head returned by bh2jh(). This is caused for example by the following race: TASK1 TASK2 journal_commit_transaction() ... processing t_forget list __journal_refile_buffer(jh); if (!jh->b_transaction) { jbd_unlock_bh_state(bh); journal_try_to_free_buffers() journal_grab_journal_head(bh) jbd_lock_bh_state(bh) __journal_try_to_free_buffer() journal_put_journal_head(jh) journal_remove_journal_head(bh); journal_put_journal_head() in TASK2 sees that b_jcount == 0 and buffer is not part of any transaction and thus frees journal_head before TASK1 gets to doing so. Note that even buffer_head can be released by try_to_free_buffers() after journal_put_journal_head() which adds even larger opportunity for oops (but I didn't see this happen in reality). Fix the problem by making transactions hold their own journal_head reference (in b_jcount). That way we don't have to remove journal_head explicitely via journal_remove_journal_head() and instead just remove journal_head when b_jcount drops to zero. The result of this is that [__]journal_refile_buffer(), [__]journal_unfile_buffer(), and __journal_remove_checkpoint() can free journal_head which needs modification of a few callers. Also we have to be careful because once journal_head is removed, buffer_head might be freed as well. So we have to get our own buffer_head reference where it matters. Signed-off-by: Jan Kara <jack@suse.cz>
2011-06-24 21:11:59 +00:00
/* Get reference for checkpointing transaction */
journal_grab_journal_head(jh2bh(jh));
jh->b_cp_transaction = transaction;
if (!transaction->t_checkpoint_list) {
jh->b_cpnext = jh->b_cpprev = jh;
} else {
jh->b_cpnext = transaction->t_checkpoint_list;
jh->b_cpprev = transaction->t_checkpoint_list->b_cpprev;
jh->b_cpprev->b_cpnext = jh;
jh->b_cpnext->b_cpprev = jh;
}
transaction->t_checkpoint_list = jh;
}
/*
* We've finished with this transaction structure: adios...
*
* The transaction must have no links except for the checkpoint by this
* point.
*
* Called with the journal locked.
* Called with j_list_lock held.
*/
void __journal_drop_transaction(journal_t *journal, transaction_t *transaction)
{
assert_spin_locked(&journal->j_list_lock);
if (transaction->t_cpnext) {
transaction->t_cpnext->t_cpprev = transaction->t_cpprev;
transaction->t_cpprev->t_cpnext = transaction->t_cpnext;
if (journal->j_checkpoint_transactions == transaction)
journal->j_checkpoint_transactions =
transaction->t_cpnext;
if (journal->j_checkpoint_transactions == transaction)
journal->j_checkpoint_transactions = NULL;
}
J_ASSERT(transaction->t_state == T_FINISHED);
J_ASSERT(transaction->t_buffers == NULL);
J_ASSERT(transaction->t_sync_datalist == NULL);
J_ASSERT(transaction->t_forget == NULL);
J_ASSERT(transaction->t_iobuf_list == NULL);
J_ASSERT(transaction->t_shadow_list == NULL);
J_ASSERT(transaction->t_log_list == NULL);
J_ASSERT(transaction->t_checkpoint_list == NULL);
J_ASSERT(transaction->t_checkpoint_io_list == NULL);
J_ASSERT(transaction->t_updates == 0);
J_ASSERT(journal->j_committing_transaction != transaction);
J_ASSERT(journal->j_running_transaction != transaction);
trace_jbd_drop_transaction(journal, transaction);
jbd_debug(1, "Dropping transaction %d, all done\n", transaction->t_tid);
kfree(transaction);
}