cluster/dht: Fix min-free-disk calculations when quota-deem-statfs is on

PROBLEM:

As part of file creation, DHT sends a statfs call to all of its
sub-volumes and expects in return the local space consumption and
availability on each one of them. This information is used by DHT to
ensure that atleast min-free-disk amount of space is left on each
sub-volume in the event that there ARE other sub-volumes with more
space available.
But when quota-deem-statfs is enabled, quota xlator on every brick
unwinds the statfs call with volume-wide consumption of disk space.
This leads to miscalculation in min-free-disk algo, thereby misleading
DHT at some point, into thinking all sub-volumes have equal available
space, in which case DHT keeps sending new file creates to subvol-0,
causing it to become 100% full at some point although there ARE other
subvols with ample space available.

FIX:

The fix is to make quota_statfs() behave as if quota xlator weren't
enabled, thereby making every brick return only its local consumption
and disk space availability.

Change-Id: I211371a1eddb220037bd36a128973938ea8124c2
BUG: 1099890
Signed-off-by: Krutika Dhananjay <kdhananj@redhat.com>
Reviewed-on: http://review.gluster.org/7845
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Raghavendra G <rgowdapp@redhat.com>
Reviewed-by: Vijay Bellur <vbellur@redhat.com>

1 files changed, 12 insertions, 4 deletions

diff --git a/xlators/features/quota/src/quota.c b/xlators/features/quota/src/quota.c
index c3e730bd1fd..06ef9615a19 100644
--- a/xlators/features/quota/src/quota.c
+++ b/xlators/features/quota/src/quota.c
@@ -3808,16 +3808,24 @@ out:
 int32_t
 quota_statfs (call_frame_t *frame, xlator_t *this, loc_t *loc, dict_t *xdata)
 {
-        quota_local_t   *local          = NULL;
-        int              op_errno       = 0;
-        int              ret            = -1;
-        quota_priv_t    *priv           = NULL;
+        int              op_errno            = 0;
+        int              ret                 = -1;
+        int8_t           ignore_deem_statfs  = 0;
+        quota_priv_t    *priv                = NULL;
+        quota_local_t   *local               = NULL;
 
         priv = this->private;
         GF_ASSERT (loc);
 
         WIND_IF_QUOTAOFF (priv->is_quota_on, off);
 
+        ret = dict_get_int8 (xdata, GF_INTERNAL_IGNORE_DEEM_STATFS,
+                             &ignore_deem_statfs);
+        ret = 0;
+
+        if (ignore_deem_statfs)
+                goto off;
+
 	if (priv->consider_statfs && loc->inode) {
                 local = quota_local_new ();
                 if (!local) {