writeback: Fix data corruption on NFS (f9b0e058) · Commits · 戴 / test

Commit "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: Reported-and-tested-by:

Dan Duval <dan.duval@oracle.com> Signed-off-by:

Jan Kara <jack@suse.cz>

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);

Admin message