[25/83] jfs: fix a couple races

From: Ben Hutchings
Date: Sun Jun 16 2013 - 18:30:17 EST

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


From: Dave Kleikamp <dave.kleikamp@xxxxxxxxxx>

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@xxxxxxxxx>
Signed-off-by: Dave Kleikamp <dave.kleikamp@xxxxxxxxxx>
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
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);

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