GFS2: quota allows exceeding hard limit

Immediately after being synced to disk, cached quotas are zeroed out and a
subsequent access of the cached quotas results in incorrect zero values. This
meant that gfs2 assumed the actual usage to be the zero (or near-zero) usage
values it found in the cached quotas and comparison against warn/limits never
triggered a quota violation.

This patch adds a new flag QDF_REFRESH that is set after a sync so that the
cached quotas are forcefully refreshed from disk on a subsequent access on
seeing this flag set.

Resolves: rhbz#675944
Signed-off-by: Abhi Das <adas@redhat.com>
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>

1 files changed, 7 insertions, 1 deletions

diff --git a/fs/gfs2/quota.c b/fs/gfs2/quota.c
index 6ec964c31dc6..e23d9864c418 100644
--- a/fs/gfs2/quota.c
+++ b/fs/gfs2/quota.c
@@ -834,6 +834,7 @@ static int do_sync(unsigned int num_qd, struct gfs2_quota_data **qda)
                         goto out_end_trans;
 
                 do_qc(qd, -qd->qd_change_sync);
+                set_bit(QDF_REFRESH, &qd->qd_flags);
         }
 
         error = 0;
@@ -929,6 +930,7 @@ int gfs2_quota_lock(struct gfs2_inode *ip, u32 uid, u32 gid)
 {
         struct gfs2_sbd *sdp = GFS2_SB(&ip->i_inode);
         struct gfs2_alloc *al = ip->i_alloc;
+        struct gfs2_quota_data *qd;
         unsigned int x;
         int error = 0;
 
@@ -942,7 +944,11 @@ int gfs2_quota_lock(struct gfs2_inode *ip, u32 uid, u32 gid)
              sort_qd, NULL);
 
         for (x = 0; x < al->al_qd_num; x++) {
-                error = do_glock(al->al_qd[x], NO_FORCE, &al->al_qd_ghs[x]);
+                int force = NO_FORCE;
+                qd = al->al_qd[x];
+                if (test_and_clear_bit(QDF_REFRESH, &qd->qd_flags))
+                        force = FORCE;
+                error = do_glock(qd, force, &al->al_qd_ghs[x]);
                 if (error)
                         break;
         }