linux-kernel - [25/83] jfs: fix a couple races

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Message-ID: <lsq.1371420097.408003952@decadent.org.uk>
Date:	Sun, 16 Jun 2013 23:01:37 +0100
From:	Ben Hutchings <ben@...adent.org.uk>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:	akpm@...ux-foundation.org,
	"Michael L. Semon" <mlsemon35@...il.com>,
	"Dave Kleikamp" <dave.kleikamp@...cle.com>
Subject: [25/83] jfs: fix a couple races

3.2.47-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Dave Kleikamp <dave.kleikamp@...cle.com>

commit 73aaa22d5ffb2630456bac2f9a4ed9b81d0d7271 upstream.

This patch fixes races uncovered by xfstests testcase 068.

One race is the result of jfs_sync() trying to write a sync point to the
journal after it has been frozen (or possibly in the process). Since
freezing sync's the journal, there is no need to write a sync point so
we simply want to return.

The second involves jfs_write_inode() being called on a deleted inode.
It calls jfs_flush_journal which is held up by the jfs_commit thread
doing the final iput on the same deleted inode, which itself is
waiting for the I_SYNC flag to be cleared. jfs_write_inode need not
do anything when i_nlink is zero, which is the easy fix.

Reported-by: Michael L. Semon <mlsemon35@...il.com>
Signed-off-by: Dave Kleikamp <dave.kleikamp@...cle.com>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 fs/jfs/inode.c      |    2 +-
 fs/jfs/jfs_logmgr.c |    3 ++-
 2 files changed, 3 insertions(+), 2 deletions(-)

--- a/fs/jfs/inode.c
+++ b/fs/jfs/inode.c
@@ -125,7 +125,7 @@ int jfs_write_inode(struct inode *inode,
 {
 	int wait = wbc->sync_mode == WB_SYNC_ALL;

-	if (test_cflag(COMMIT_Nolink, inode))
+	if (inode->i_nlink == 0)
 		return 0;
 	/*
 	 * If COMMIT_DIRTY is not set, the inode isn't really dirty.
--- a/fs/jfs/jfs_logmgr.c
+++ b/fs/jfs/jfs_logmgr.c
@@ -1058,7 +1058,8 @@ static int lmLogSync(struct jfs_log * lo
  */
 void jfs_syncpt(struct jfs_log *log, int hard_sync)
 {	LOG_LOCK(log);
-	lmLogSync(log, hard_sync);
+	if (!test_bit(log_QUIESCE, &log->flag))
+		lmLogSync(log, hard_sync);
 	LOG_UNLOCK(log);
 }

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