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Commit f9b0e058 authored by Jan Kara's avatar Jan Kara Committed by Fengguang Wu
Browse files

writeback: Fix data corruption on NFS 



Commit 4f8ad655 "writeback: Refactor writeback_single_inode()" added
a condition to skip clean inode. However this is wrong in WB_SYNC_ALL
mode because there we also want to wait for outstanding writeback on
possibly clean inode. This was causing occasional data corruption issues
on NFS because it uses sync_inode() to make sure all outstanding writes
are flushed to the server before truncating the inode and with
sync_inode() returning prematurely file was sometimes extended back
by an outstanding write after it was truncated.

So modify the test to also check for pages under writeback in
WB_SYNC_ALL mode.

CC: stable@vger.kernel.org # >= 3.5
Fixes: 4f8ad655
Reported-and-tested-by: default avatarDan Duval <dan.duval@oracle.com>
Signed-off-by: default avatarJan Kara <jack@suse.cz>
parent 374b1057

fs/fs-writeback.c

+9 −6
Original line number Diff line number Diff line
@@ -516,13 +516,16 @@ writeback_single_inode(struct inode *inode, struct bdi_writeback *wb, 
	}

	WARN_ON(inode->i_state & I_SYNC);

	/*

	 * Skip inode if it is clean. We don't want to mess with writeback

	 * lists in this function since flusher thread may be doing for example

	 * sync in parallel and if we move the inode, it could get skipped. So

	 * here we make sure inode is on some writeback list and leave it there

	 * unless we have completely cleaned the inode.

	 */

	if (!(inode->i_state & I_DIRTY))

	 * Skip inode if it is clean and we have no outstanding writeback in

	 * WB_SYNC_ALL mode. We don't want to mess with writeback lists in this

	 * function since flusher thread may be doing for example sync in

	 * parallel and if we move the inode, it could get skipped. So here we

	 * make sure inode is on some writeback list and leave it there unless

	 * we have completely cleaned the inode.

	 */

	if (!(inode->i_state & I_DIRTY) &&

	    (wbc->sync_mode != WB_SYNC_ALL ||

	     !mapping_tagged(inode->i_mapping, PAGECACHE_TAG_WRITEBACK)))

		goto out;

	inode->i_state |= I_SYNC;

	spin_unlock(&inode->i_lock);