cluster/dht: Make rebalance honor min-free-disk

test:  Manual

created files of size 1K on 2 brick(of size 1GB) setup .
added a brick of size 16GB.
set min-free-disk to 12GB(so that first two bricks won't receive any files).
removed one of the 1st brick of size 1GB.

Logs from test:
[2017-04-12 08:52:08.196484] W [MSGID: 0] [dht-rebalance.c:895:__dht_check_free_space]
 0-test1-dht: Write will cross min-free-disk for file - /tile32 on subvol - test1-client-1.
Looking for new subvol.

[2017-04-12 08:52:08.196904] I [MSGID: 0] [dht-rebalance.c:925:__dht_check_free_space]
0-test1-dht: new target found - test1-client-2 for file - /tile32

 - Post migration we have two files. The new destination (/brick/1) has the data file
[root@vm1 ~]# ll /brick/1/tile32
-rw-r--r--. 2 root root 0 Apr 12 14:22 /brick/1/tile32

 - On the old target the linkto file is there with linkto xattr pointing to /brick/1
[root@vm1 ~]# ll /tmp/2/tile32
---------T. 2 root root 1000 Apr 12 14:22 /tmp/2/tile32
[root@vm1 ~]# getfattr -m . -de text /tmp/2/tile32
getfattr: Removing leading '/' from absolute path names
security.selinux="unconfined_u:object_r:user_tmp_t:s0"
trusted.gfid="����:Aс�#�/'b2"
trusted.glusterfs.dht.linkto="test1-client-2"

Marking ./tests/features/worm_sh.t as bad test.
Reason being, this patch failed on master branch as well and it has nothing
to do with rebalance/remove-brick.

BUG: 1441508
Change-Id: I90bae251cda3d957a49cdceda90cd08311a392fb
Signed-off-by: Susant Palai <spalai@redhat.com>
Reviewed-on: https://review.gluster.org/17034
Smoke: Gluster Build System <jenkins@build.gluster.org>
NetBSD-regression: NetBSD Build System <jenkins@build.gluster.org>
Reviewed-by: Amar Tumballi <amarts@redhat.com>
Reviewed-by: Raghavendra G <rgowdapp@redhat.com>
CentOS-regression: Gluster Build System <jenkins@build.gluster.org>

1 files changed, 1 insertions, 1 deletions

diff --git a/xlators/storage/posix/src/posix.c b/xlators/storage/posix/src/posix.c
index 57575cc4c53..999e8f60534 100644
--- a/xlators/storage/posix/src/posix.c
+++ b/xlators/storage/posix/src/posix.c
@@ -741,7 +741,7 @@ posix_do_fallocate (call_frame_t *frame, xlator_t *this, fd_t *fd,
                 goto out;
         }
 
-        if (dict_get (xdata, GLUSTERFS_WRITE_UPDATE_ATOMIC)) {
+        if (xdata && dict_get (xdata, GLUSTERFS_WRITE_UPDATE_ATOMIC)) {
                 locked = _gf_true;
                 pthread_mutex_lock (&ctx->write_atomic_lock);
         }