Commit 81be12c8 authored by Jan Kara's avatar Jan Kara Committed by Theodore Ts'o
Browse files

jbd2: fix sending of data flush on journal commit 




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: default avatarJan Kara <jack@suse.cz>
Signed-off-by: default avatar"Theodore Ts'o" <tytso@mit.edu>
parent b221349f

fs/jbd2/commit.c

+1 −2
Original line number Diff line number Diff line
@@ -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);

fs/jbd2/transaction.c

+7 −0
Original line number Diff line number Diff line
@@ -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) {

include/linux/jbd2.h

+3 −1
Original line number Diff line number Diff line
@@ -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

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