[PATCH v2] xfs: fix error handling in xfs_qm_log_quotaoff()

[Brian Foster]

The error handling in xfs_qm_log_quotaoff() has a couple problems. If
xfs_trans_commit() fails, we fall through to the error block and call
xfs_trans_cancel(). This is incorrect on commit failure. If
xfs_trans_reserve() fails, we jump to the error block, cancel the tp and
restore the superblock qflags to oldsbqflag. However, oldsbqflag has
been initialized to zero and not yet updated from the original flags so
we set the flags to zero.

Fix up the error handling in xfs_qm_log_quotaoff() to not restore flags
if they haven't been modified and not cancel the tp on commit failure.
Remove the flag restore code altogether because commit error is the only
failure condition and we don't know whether the transaction made it to
disk.

Reported-by: Dan Carpenter <***@oracle.com>
Signed-off-by: Brian Foster <***@redhat.com>
---

v2:
- Don't restore sb_qflags on tp commit failure.
v1: http://oss.sgi.com/archives/xfs/2014-10/msg00314.html

fs/xfs/xfs_qm_syscalls.c | 26 ++++++++++----------------
1 file changed, 10 insertions(+), 16 deletions(-)

diff --git a/fs/xfs/xfs_qm_syscalls.c b/fs/xfs/xfs_qm_syscalls.c
index 80f2d77..d1e0ab7 100644
--- a/fs/xfs/xfs_qm_syscalls.c
+++ b/fs/xfs/xfs_qm_syscalls.c
@@ -784,19 +784,21 @@ xfs_qm_log_quotaoff(
{
xfs_trans_t *tp;
int error;
- xfs_qoff_logitem_t *qoffi=NULL;
- uint oldsbqflag=0;
+ xfs_qoff_logitem_t *qoffi;
+
+ *qoffstartp = NULL;

tp = xfs_trans_alloc(mp, XFS_TRANS_QM_QUOTAOFF);
error = xfs_trans_reserve(tp, &M_RES(mp)->tr_qm_quotaoff, 0, 0);
- if (error)
- goto error0;
+ if (error) {
+ xfs_trans_cancel(tp, 0);
+ goto out;
+ }

qoffi = xfs_trans_get_qoff_item(tp, NULL, flags & XFS_ALL_QUOTA_ACCT);
xfs_trans_log_quotaoff_item(tp, qoffi);

spin_lock(&mp->m_sb_lock);
- oldsbqflag = mp->m_sb.sb_qflags;
mp->m_sb.sb_qflags = (mp->m_qflags & ~(flags)) & XFS_MOUNT_QUOTA_ALL;
spin_unlock(&mp->m_sb_lock);

@@ -809,19 +811,11 @@ xfs_qm_log_quotaoff(
*/
xfs_trans_set_sync(tp);
error = xfs_trans_commit(tp, 0);
+ if (error)
+ goto out;

-error0:
- if (error) {
- xfs_trans_cancel(tp, 0);
- /*
- * No one else is modifying sb_qflags, so this is OK.
- * We still hold the quotaofflock.
- */
- spin_lock(&mp->m_sb_lock);
- mp->m_sb.sb_qflags = oldsbqflag;
- spin_unlock(&mp->m_sb_lock);
- }
*qoffstartp = qoffi;
+out:
return error;
}