cluster/dht: Skip file migration if the subvol that meets min-free-disk

criteria happens to be the same subvol containing data-file

Rebalance need to figure out a new subvol in case the hashed subvol
does not have enough space. In the process of figuring out the new subvol,
we need to ignore the source subvol, otherwise it will lead to data loss.

Test: Manual
Ran the following
sizeof /tmp/1: 1.5GB
sizeof /brick/1: 16GB
sizeof /tmp/2: 1.5GB
<start>

glusterd;  gluster v create test1 vm1:/brick/1 vm1:/tmp/1;
gluster v start test1;
mount -t glusterfs vm1:test1 /mnt;
for i in {1..2000}
do
dd if=/dev/zero of=/mnt/file$i bs=1KB count=1 &> /dev/null;
done
gluster v add-brick test1 vm1:/tmp/2
gluster v set test1 min-free-disk 12GB
gluster v remove-brick test1 vm1:/tmp/1 star
<end>

file count and data were intact.

Change-Id: Ib8fc8467a3d48a7c12958824c4f0b88e160b86c1
BUG: 1441508
Signed-off-by: Susant Palai <spalai@redhat.com>
Reviewed-on: https://review.gluster.org/17064
Smoke: Gluster Build System <jenkins@build.gluster.org>
NetBSD-regression: NetBSD Build System <jenkins@build.gluster.org>
CentOS-regression: Gluster Build System <jenkins@build.gluster.org>
Reviewed-by: Raghavendra G <rgowdapp@redhat.com>

1 files changed, 13 insertions, 6 deletions

diff --git a/xlators/cluster/dht/src/dht-diskusage.c b/xlators/cluster/dht/src/dht-diskusage.c
index 13698a9616d..05592154e30 100644
--- a/xlators/cluster/dht/src/dht-diskusage.c
+++ b/xlators/cluster/dht/src/dht-diskusage.c
@@ -315,7 +315,7 @@ dht_free_disk_available_subvol (xlator_t *this, xlator_t *subvol,
 
         LOCK (&conf->subvolume_lock);
 	{
-                avail_subvol = dht_subvol_with_free_space_inodes(this, subvol,
+                avail_subvol = dht_subvol_with_free_space_inodes(this, subvol, NULL,
                                                                  layout, 0);
                 if(!avail_subvol)
                 {
@@ -340,8 +340,8 @@ out:
 }
 
 static inline
-int32_t dht_subvol_has_err (dht_conf_t *conf, xlator_t *this,
-                                         dht_layout_t *layout)
+int32_t dht_subvol_has_err (dht_conf_t *conf, xlator_t *this, xlator_t *ignore,
+                            dht_layout_t *layout)
 {
         int ret = -1;
         int i   = 0;
@@ -349,6 +349,13 @@ int32_t dht_subvol_has_err (dht_conf_t *conf, xlator_t *this,
         if (!this || !layout)
                 goto out;
 
+        /* this check is meant for rebalance process. The source of the file
+         * should be ignored for space check */
+        if (this == ignore) {
+                goto out;
+        }
+
+
         /* check if subvol has layout errors, before selecting it */
         for (i = 0; i < layout->cnt; i++) {
                 if (!strcmp (layout->list[i].xlator->name, this->name) &&
@@ -376,7 +383,7 @@ out:
 
 /*Get subvolume which has both space and inodes more than the min criteria*/
 xlator_t *
-dht_subvol_with_free_space_inodes(xlator_t *this, xlator_t *subvol,
+dht_subvol_with_free_space_inodes(xlator_t *this, xlator_t *subvol, xlator_t *ignore,
                                   dht_layout_t *layout, uint64_t filesize)
 {
         int i = 0;
@@ -398,7 +405,7 @@ dht_subvol_with_free_space_inodes(xlator_t *this, xlator_t *subvol,
                 /* check if subvol has layout errors and also it is not a
                  * decommissioned brick, before selecting it */
                 ignore_subvol = dht_subvol_has_err (conf, conf->subvolumes[i],
-                                                    layout);
+                                                    ignore, layout);
                 if (ignore_subvol)
                         continue;
 
@@ -463,7 +470,7 @@ dht_subvol_maxspace_nonzeroinode (xlator_t *this, xlator_t *subvol,
                 /* check if subvol has layout errors and also it is not a
                  * decommissioned brick, before selecting it*/
 
-                ignore_subvol = dht_subvol_has_err (conf, conf->subvolumes[i],
+                ignore_subvol = dht_subvol_has_err (conf, conf->subvolumes[i], NULL,
                                                     layout);
                 if (ignore_subvol)
                         continue;