xfs: don't lose solo superblock counter update transactions

commit c817aabd3b08e8770d89a9a29ae80fead561a1a1 upstream

Superblock counter updates are tracked via per-transaction counters in
the xfs_trans object.  These changes are then turned into dirty log
items in xfs_trans_apply_sb_deltas just prior to commiting the log items
to the CIL.

However, updating the per-transaction counter deltas do not cause
XFS_TRANS_DIRTY to be set on the transaction.  In other words, a pure sb
counter update will be silently discarded if there are no other dirty
log items attached to the transaction.

This is currently not the case anywhere in the filesystem because sb
counter updates always dirty at least one other metadata item, but let's
not leave a logic bomb.

Cc: <stable@vger.kernel.org> # v2.6.35
Fixes: 0924378a689ccb ("xfs: split out iclog writing from xfs_trans_commit()")
Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/fs/xfs/xfs_trans.c b/fs/xfs/xfs_trans.c
index 001d9bec4ed57149a17f39ccab114fd4a9ef751e..ee46051db12dde0a253ef1963efb3299332f8bb3 100644 (file)
--- a/fs/xfs/xfs_trans.c
+++ b/fs/xfs/xfs_trans.c
@@ -834,6 +834,13 @@ __xfs_trans_commit(
 
        trace_xfs_trans_commit(tp, _RET_IP_);
 
+       /*
+        * Commit per-transaction changes that are not already tracked through
+        * log items.  This can add dirty log items to the transaction.
+        */
+       if (tp->t_flags & XFS_TRANS_SB_DIRTY)
+               xfs_trans_apply_sb_deltas(tp);
+
        error = xfs_trans_run_precommits(tp);
        if (error)
                goto out_unreserve;
@@ -864,8 +871,6 @@ __xfs_trans_commit(
        /*
         * If we need to update the superblock, then do it now.
         */
-       if (tp->t_flags & XFS_TRANS_SB_DIRTY)
-               xfs_trans_apply_sb_deltas(tp);
        xfs_trans_apply_dquot_deltas(tp);
 
        xlog_cil_commit(log, tp, &commit_seq, regrant);