cluster/distribute: Rebalance should also verify free inodes

Currently during `MIGRATE_DATA` we never verified about the total
inode usage among new and old bricks. Such checks are available for
disk space usage but it is also needed for inodes during data
migration. Such a check leads to uniform outcome of file distribution
upon rebalance.

Patch provides:

- Check dst_inodes < src_inodes, a friendly `warning` message to
  indicate we have to ignore such an attempt
- Rename __dht_check_free_space() --> __dht_check_free_space_and_inodes()

Change-Id: I7bc4dd8b507883f0fb836300e99f0bb083493f5f
BUG: 982919
Signed-off-by: Harshavardhana <harsha@harshavardhana.net>
Reviewed-on: http://review.gluster.org/5948
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Reviewed-by: Anand Avati <avati@redhat.com>

1 files changed, 22 insertions, 5 deletions

diff --git a/xlators/cluster/dht/src/dht-rebalance.c b/xlators/cluster/dht/src/dht-rebalance.c
index 5300ff2fe7a..c6a8e417721 100644
--- a/xlators/cluster/dht/src/dht-rebalance.c
+++ b/xlators/cluster/dht/src/dht-rebalance.c
@@ -332,8 +332,8 @@ out:
 }
 
 static inline int
-__dht_check_free_space (xlator_t *to, xlator_t *from, loc_t *loc,
-                        struct iatt *stbuf, int flag)
+__dht_check_free_space_and_inodes (xlator_t *to, xlator_t *from, loc_t *loc,
+                                   struct iatt *stbuf, int flag)
 {
         struct statvfs  src_statfs = {0,};
         struct statvfs  dst_statfs = {0,};
@@ -379,9 +379,27 @@ __dht_check_free_space (xlator_t *to, xlator_t *from, loc_t *loc,
                 goto out;
         }
 
+        /* NOTE:
+           For dynamically allocated inode filesystems since we have no
+           awareness on inodes, this logic fits well so that distribute
+           rebalance has nothing to worry about total inodes rather let the
+           files be `rebalanced` on the basis of hashing.
+        */
+        if (dst_statfs.f_files && src_statfs.f_files) {
+                if (dst_statfs.f_ffree < src_statfs.f_ffree) {
+                        gf_log (this->name, GF_LOG_WARNING,
+                                "data movement attempted from node (%s) with"
+                                " plenty free inodes to a node (%s) with "
+                                "scanty free inodes (%s)",
+                                from->name, to->name, loc->path);
+                        ret = 1;
+                        goto out;
+                }
+        }
+
 check_avail_space:
         if (((dst_statfs.f_bavail * dst_statfs.f_bsize) /
-              GF_DISK_SECTOR_SIZE) < stbuf->ia_blocks) {
+             GF_DISK_SECTOR_SIZE) < stbuf->ia_blocks) {
                 gf_log (this->name, GF_LOG_ERROR,
                         "data movement attempted from node (%s) with "
                         "to node (%s) which does not have required free space"
@@ -389,7 +407,6 @@ check_avail_space:
                 ret = 1;
                 goto out;
         }
-
         ret = 0;
 out:
         return ret;
@@ -714,7 +731,7 @@ dht_migrate_file (xlator_t *this, loc_t *loc, xlator_t *from, xlator_t *to,
         if (ret)
                 goto out;
 
-        ret = __dht_check_free_space (to, from, loc, &stbuf, flag);
+        ret = __dht_check_free_space_and_inodes (to, from, loc, &stbuf, flag);
         if (ret) {
                 goto out;
         }