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[3.11.y.z,extended,stable] Patch "writeback: Fix data corruption on NFS" has been added to staging queue

Message ID 1390302176-15463-1-git-send-email-luis.henriques@canonical.com
State New
Headers show

Commit Message

Luis Henriques Jan. 21, 2014, 11:02 a.m. UTC
This is a note to let you know that I have just added a patch titled

    writeback: Fix data corruption on NFS

to the linux-3.11.y-queue branch of the 3.11.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.11.y-queue

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.11.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

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From 90c28061ad359f393c2c8474dbf35b296b6874a9 Mon Sep 17 00:00:00 2001
From: Jan Kara <jack@suse.cz>
Date: Sat, 14 Dec 2013 04:21:26 +0800
Subject: writeback: Fix data corruption on NFS

commit f9b0e058cbd04ada76b13afffa7e1df830543c24 upstream.

Commit 4f8ad655dbc8 "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.

Fixes: 4f8ad655dbc82cf05d2edc11e66b78a42d38bf93
Reported-and-tested-by: Dan Duval <dan.duval@oracle.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>
---
 fs/fs-writeback.c | 15 +++++++++------
 1 file changed, 9 insertions(+), 6 deletions(-)

--
1.8.3.2
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Patch

diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index 68851ff..52e5934 100644
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -508,13 +508,16 @@  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.
+	 * 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))
+	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);