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jbd2: fix sending of data flush on journal commit

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In data=ordered mode, it's theoretically possible (however rare) that
an inode is filed to transaction's t_inode_list and a flusher thread
writes all the data and inode is reclaimed before the transaction
starts to commit.  In such a case, we could erroneously omit sending a
flush to file system device when it is different from the journal
device (because data can still be in disk cache only).

Fix the problem by setting a flag in a transaction when some inode is added
to it and then send disk flush in the commit code when the flag is set.

Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
This commit is contained in:
Jan Kara 2011-05-24 11:52:40 -04:00 committed by Theodore Ts'o
parent b221349fa8
commit 81be12c817
3 changed files with 11 additions and 3 deletions
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3
fs/jbd2/commit.c
View File

@ -219,7 +219,6 @@ static int journal_submit_data_buffers(journal_t *journal,
ret = err;
spin_lock(&journal->j_list_lock);
J_ASSERT(jinode->i_transaction == commit_transaction);
commit_transaction->t_flushed_data_blocks = 1;
clear_bit(__JI_COMMIT_RUNNING, &jinode->i_flags);
smp_mb__after_clear_bit();
wake_up_bit(&jinode->i_flags, __JI_COMMIT_RUNNING);
@ -683,7 +682,7 @@ start_journal_io:
* then we must flush the file system device before we issue
* the commit record
*/
if (commit_transaction->t_flushed_data_blocks &&
if (commit_transaction->t_need_data_flush &&
(journal->j_fs_dev != journal->j_dev) &&
(journal->j_flags & JBD2_BARRIER))
blkdev_issue_flush(journal->j_fs_dev, GFP_KERNEL, NULL);

7
fs/jbd2/transaction.c
View File

@ -2147,6 +2147,13 @@ int jbd2_journal_file_inode(handle_t *handle, struct jbd2_inode *jinode)
jinode->i_next_transaction == transaction)
goto done;
/*
* We only ever set this variable to 1 so the test is safe. Since
* t_need_data_flush is likely to be set, we do the test to save some
* cacheline bouncing
*/
if (!transaction->t_need_data_flush)
transaction->t_need_data_flush = 1;
/* On some different transaction's list - should be
* the committing one */
if (jinode->i_transaction) {

4
include/linux/jbd2.h
View File

@ -658,7 +658,9 @@ struct transaction_s
* waiting for it to finish.
*/
unsigned int t_synchronous_commit:1;
unsigned int t_flushed_data_blocks:1;
/* Disk flush needs to be sent to fs partition [no locking] */
int t_need_data_flush;
/*
* For use by the filesystem to store fs-specific data