cluster/dht: Use percentages for space check

With heterogenous bricks now being supported in DHT
we could run into issues where files are not migrated
even though there is sufficient space in newly added bricks
which just happen to be considerably smaller than older
bricks. Using percentages instead of absolute available
space for space checks can mitigate that to some extent.

Marking bug-1247563.t as that used to depend on the easier
code to prevent a file from migrating. This will be removed
once we find a way to force a file migration failure.

> Change-Id: I3452520511f304dbf5af86f0632f654a92fcb647
> BUG: 1529440
> Signed-off-by: N Balachandran <nbalacha@redhat.com>

Change-Id: I3452520511f304dbf5af86f0632f654a92fcb647
BUG: 1530455
Signed-off-by: N Balachandran <nbalacha@redhat.com>

2 files changed, 25 insertions, 5 deletions

diff --git a/tests/bugs/distribute/bug-1247563.t b/tests/bugs/distribute/bug-1247563.t
index f7f92582e04..a2fc722896f 100644
--- a/tests/bugs/distribute/bug-1247563.t
+++ b/tests/bugs/distribute/bug-1247563.t
@@ -30,6 +30,7 @@ TEST glusterfs --acl -s $H0 --volfile-id $V0 $M0
 TEST mkdir $M0/dir1
 
 echo "Testing pacls on rebalance" > $M0/dir1/FILE1
+
 FPATH1=`find $B0/ -name FILE1`
 
 # Rename the file to create a linkto, for rebalance to
@@ -55,3 +56,7 @@ COUNT=`getfacl $FPATH2 |grep -c "user:root:rwx"`
 EXPECT "0" echo $COUNT
 
 cleanup;
+
+
+#G_TESTDEF_TEST_STATUS_CENTOS6=BAD_TEST,BUG=000000
+#G_TESTDEF_TEST_STATUS_NETBSD7=BAD_TEST,BUG=000000
diff --git a/xlators/cluster/dht/src/dht-rebalance.c b/xlators/cluster/dht/src/dht-rebalance.c
index 72826e5ff32..d0945650c9e 100644
--- a/xlators/cluster/dht/src/dht-rebalance.c
+++ b/xlators/cluster/dht/src/dht-rebalance.c
@@ -894,8 +894,10 @@ __dht_check_free_space (xlator_t *this, xlator_t *to, xlator_t *from,
         dht_layout_t   *layout     = NULL;
         uint64_t        src_statfs_blocks = 1;
         uint64_t        dst_statfs_blocks = 1;
-        double          post_availspacepercent = 0;
+        double          dst_post_availspacepercent = 0;
+        double          src_post_availspacepercent = 0;
         uint64_t        file_blocks = 0;
+        uint64_t        src_total_blocks = 0;
         uint64_t        dst_total_blocks = 0;
 
         xdata = dict_new ();
@@ -956,6 +958,10 @@ __dht_check_free_space (xlator_t *this, xlator_t *to, xlator_t *from,
                            (dst_statfs.f_frsize /
                            GF_DISK_SECTOR_SIZE);
 
+        src_total_blocks = src_statfs.f_blocks *
+                           (src_statfs.f_frsize /
+                           GF_DISK_SECTOR_SIZE);
+
         /* if force option is given, do not check for space @ dst.
          * Check only if space is avail for the file */
         if (flag != GF_DHT_MIGRATE_DATA)
@@ -967,6 +973,9 @@ __dht_check_free_space (xlator_t *this, xlator_t *to, xlator_t *from,
            subvol gains certain 'blocks' of free space. A valid check is
            necessary here to avoid errorneous move to destination where
            the space could be scantily available.
+           With heterogenous brick support, an actual space comparison could
+           prevent any files being migrated to newly added bricks if they are
+           smaller then the free space available on the existing bricks.
          */
         if (stbuf) {
                 if (!conf->use_fallocate) {
@@ -980,7 +989,13 @@ __dht_check_free_space (xlator_t *this, xlator_t *to, xlator_t *from,
                         }
                 }
 
-                if (dst_statfs_blocks <= src_statfs_blocks) {
+                src_post_availspacepercent =
+                        ((src_statfs_blocks + file_blocks) * 100) / src_total_blocks;
+
+                dst_post_availspacepercent =
+                        (dst_statfs_blocks * 100) / dst_total_blocks;
+
+                if (dst_post_availspacepercent < src_post_availspacepercent) {
                         gf_msg (this->name, GF_LOG_WARNING, 0,
                                 DHT_MSG_MIGRATE_FILE_FAILED,
                                 "data movement of file "
@@ -1001,15 +1016,15 @@ __dht_check_free_space (xlator_t *this, xlator_t *to, xlator_t *from,
 
 check_avail_space:
         if (conf->disk_unit == 'p' && dst_statfs.f_blocks) {
-                post_availspacepercent =
+                dst_post_availspacepercent =
                         (dst_statfs_blocks * 100) / dst_total_blocks;
 
                 gf_msg_debug (this->name, 0, "file : %s, post_availspacepercent"
                               " : %lf f_bavail : %lu min-free-disk: %lf",
-                              loc->path, post_availspacepercent,
+                              loc->path, dst_post_availspacepercent,
                               dst_statfs.f_bavail, conf->min_free_disk);
 
-                if (post_availspacepercent < conf->min_free_disk) {
+                if (dst_post_availspacepercent < conf->min_free_disk) {
                         gf_msg (this->name, GF_LOG_WARNING, 0, 0,
                                 "Write will cross min-free-disk for "
                                 "file - %s on subvol - %s. Looking "