[3.5.y.z extended stable] Patch "ocfs2: fix quota file corruption" has been added to staging queue

[Luis Henriques]

This is a note to let you know that I have just added a patch titled

    ocfs2: fix quota file corruption

to the linux-3.5.y-queue branch of the 3.5.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-3.5.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 3.5.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

------

>From 1314e83c9b4bcad94af66a1260a9131593d15b05 Mon Sep 17 00:00:00 2001
From: Jan Kara <jack at suse.cz>
Date: Mon, 3 Mar 2014 15:38:32 -0800
Subject: ocfs2: fix quota file corruption

commit 15c34a760630ca2c803848fba90ca0646a9907dd upstream.

Global quota files are accessed from different nodes.  Thus we cannot
cache offset of quota structure in the quota file after we drop our node
reference count to it because after that moment quota structure may be
freed and reallocated elsewhere by a different node resulting in
corruption of quota file.

Fix the problem by clearing dq_off when we are releasing dquot structure.
We also remove the DB_READ_B handling because it is useless -
DQ_ACTIVE_B is set iff DQ_READ_B is set.

Signed-off-by: Jan Kara <jack at suse.cz>
Cc: Goldwyn Rodrigues <rgoldwyn at suse.de>
Cc: Joel Becker <jlbec at evilplan.org>
Reviewed-by: Mark Fasheh <mfasheh at suse.de>
Signed-off-by: Andrew Morton <akpm at linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds at linux-foundation.org>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 fs/ocfs2/quota_global.c | 27 +++++++++++++++++----------
 fs/ocfs2/quota_local.c  |  4 ----
 2 files changed, 17 insertions(+), 14 deletions(-)

diff --git a/fs/ocfs2/quota_global.c b/fs/ocfs2/quota_global.c
index 0a86e30..c8f6801 100644
--- a/fs/ocfs2/quota_global.c
+++ b/fs/ocfs2/quota_global.c
@@ -710,6 +710,12 @@ static int ocfs2_release_dquot(struct dquot *dquot)
 	 */
 	if (status < 0)
 		mlog_errno(status);
+	/*
+	 * Clear dq_off so that we search for the structure in quota file next
+	 * time we acquire it. The structure might be deleted and reallocated
+	 * elsewhere by another node while our dquot structure is on freelist.
+	 */
+	dquot->dq_off = 0;
 	clear_bit(DQ_ACTIVE_B, &dquot->dq_flags);
 out_trans:
 	ocfs2_commit_trans(osb, handle);
@@ -748,16 +754,17 @@ static int ocfs2_acquire_dquot(struct dquot *dquot)
 	status = ocfs2_lock_global_qf(info, 1);
 	if (status < 0)
 		goto out;
-	if (!test_bit(DQ_READ_B, &dquot->dq_flags)) {
-		status = ocfs2_qinfo_lock(info, 0);
-		if (status < 0)
-			goto out_dq;
-		status = qtree_read_dquot(&info->dqi_gi, dquot);
-		ocfs2_qinfo_unlock(info, 0);
-		if (status < 0)
-			goto out_dq;
-	}
-	set_bit(DQ_READ_B, &dquot->dq_flags);
+	status = ocfs2_qinfo_lock(info, 0);
+	if (status < 0)
+		goto out_dq;
+	/*
+	 * We always want to read dquot structure from disk because we don't
+	 * know what happened with it while it was on freelist.
+	 */
+	status = qtree_read_dquot(&info->dqi_gi, dquot);
+	ocfs2_qinfo_unlock(info, 0);
+	if (status < 0)
+		goto out_dq;

 	OCFS2_DQUOT(dquot)->dq_use_count++;
 	OCFS2_DQUOT(dquot)->dq_origspace = dquot->dq_dqb.dqb_curspace;
diff --git a/fs/ocfs2/quota_local.c b/fs/ocfs2/quota_local.c
index f100bf7..b6cfcf2 100644
--- a/fs/ocfs2/quota_local.c
+++ b/fs/ocfs2/quota_local.c
@@ -1300,10 +1300,6 @@ int ocfs2_local_release_dquot(handle_t *handle, struct dquot *dquot)
 	ocfs2_journal_dirty(handle, od->dq_chunk->qc_headerbh);

 out:
-	/* Clear the read bit so that next time someone uses this
-	 * dquot he reads fresh info from disk and allocates local
-	 * dquot structure */
-	clear_bit(DQ_READ_B, &dquot->dq_flags);
 	return status;
 }

--
1.9.0