ocfs2: Fix double put of recount tree in ocfs2_lock_refcount_tree()

ocfs2: Fix double put of recount tree in ocfs2_lock_refcount_tree()

Orabug: 24759721

In ocfs2_lock_refcount_tree, if ocfs2_read_refcount_block() returns error,
we do ocfs2_refcount_tree_put twice (once in ocfs2_unlock_refcount_tree
and once outside it), thereby reducing the refcount of the refcount tree
twice, but we dont delete the tree in this case. This will make refcnt
of the tree = 0 and the ocfs2_refcount_tree_put will eventually call
ocfs2_mark_lockres_freeing, setting OCFS2_LOCK_FREEING for the
refcount_tree->rf_lockres.

The error returned by ocfs2_read_refcount_block is propagated all the way
back and for next iteration of write, ocfs2_lock_refcount_tree gets the
same tree back from ocfs2_get_refcount_tree because we havent deleted the
tree. Now we have the same tree, but OCFS2_LOCK_FREEING is set for
rf_lockres and eventually, when _ocfs2_lock_refcount_tree is called in
this iteration, BUG_ON( __ocfs2_cluster_lock:1395 ERROR: Cluster lock
called on freeing lockres T00000000000000000386019775b08d! flags 0x81) is
triggerred.

Call stack:

(loop16,11155,0):ocfs2_lock_refcount_tree:482 ERROR: status = -5
(loop16,11155,0):ocfs2_refcount_cow_hunk:3497 ERROR: status = -5
(loop16,11155,0):ocfs2_refcount_cow:3560 ERROR: status = -5
(loop16,11155,0):ocfs2_prepare_inode_for_refcount:2111 ERROR: status = -5
(loop16,11155,0):ocfs2_prepare_inode_for_write:2190 ERROR: status = -5
(loop16,11155,0):ocfs2_file_write_iter:2331 ERROR: status = -5
(loop16,11155,0):__ocfs2_cluster_lock:1395 ERROR: bug expression:
lockres->l_flags & OCFS2_LOCK_FREEING

(loop16,11155,0):__ocfs2_cluster_lock:1395 ERROR: Cluster lock called on
freeing lockres T00000000000000000386019775b08d! flags 0x81

------------[ cut here ]------------
kernel BUG at fs/ocfs2/dlmglue.c:1395!

invalid opcode: 0000 [#1] SMP  CPU 0
Modules linked in: tun ocfs2 jbd2 xen_blkback xen_netback xen_gntdev ..
sd_mod crc_t10dif ext3 jbd mbcache

Pid: 11155, comm: loop16 Tainted: G        W   2.6.39-400.279.1.el5uek #1
Oracle Corporation ORACLE SERVER X5-2/ASM,MOTHERBOARD,1U
RIP: e030:[<ffffffffa082137c>]  [<ffffffffa082137c>]
__ocfs2_cluster_lock+0x31c/0x740 [ocfs2]
RSP: e02b:ffff88017c0138a0  EFLAGS: 00010086
RAX: 000000000000008b RBX: ffff8801b5374300 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000004
RBP: ffff88017c013980 R08: 0000000000206db1 R09: ffff8800000bbf20
R10: 0000000000000000 R11: 0000000000000001 R12: ffff88017bd25848
R13: 1000000000000800 R14: ffff8801b5374948 R15: 0000000000000005
FS:  00007f8198d746e0(0000) GS:ffff8801d6600000(0000) knlGS:0000000000000000
CS:  e033 DS: 0000 ES: 0000 CR0: 000000008005003b
CR2: 00007f641d181110 CR3: 000000017c15b000 CR4: 0000000000002660
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
Process loop16 (pid: 11155, threadinfo ffff88017c010000, task
ffff8801b5374300)
Stack:
 ffff88017bd25880 0000000000000081 000000017c013920 ffff88017c013960
 000000000000001d 0000000000000001 ffff88017bd258b4 0000000000000000
 ffff880172006000 00000000a07fa410 ffff88017bd202b4 0000000000000000
Call Trace:
 [<ffffffffa08227de>] ocfs2_refcount_lock+0xae/0x130 [ocfs2]
 [<ffffffffa0846b89>] ? __ocfs2_lock_refcount_tree+0x29/0xe0 [ocfs2]
 [<ffffffff81509dde>] ? _raw_spin_lock+0xe/0x20
 [<ffffffffa0846b89>] __ocfs2_lock_refcount_tree+0x29/0xe0 [ocfs2]
 [<ffffffffa084d47d>] ocfs2_lock_refcount_tree+0xdd/0x320 [ocfs2]
 [<ffffffffa084de3b>] ocfs2_refcount_cow_hunk+0x1cb/0x440 [ocfs2]
 [<ffffffffa084e159>] ocfs2_refcount_cow+0xa9/0x1d0 [ocfs2]
 [<ffffffffa08291c7>] ? ocfs2_prepare_inode_for_refcount+0x67/0x200 [ocfs2]
 [<ffffffffa0829275>] ocfs2_prepare_inode_for_refcount+0x115/0x200 [ocfs2]
 [<ffffffffa081f394>] ? ocfs2_inode_unlock+0xd4/0x140 [ocfs2]
 [<ffffffffa082969b>] ocfs2_prepare_inode_for_write+0x33b/0x470 [ocfs2]
 [<ffffffffa0822620>] ? ocfs2_rw_lock+0x80/0x190 [ocfs2]
 [<ffffffffa082c150>] ocfs2_file_write_iter+0x220/0x8c0 [ocfs2]
 [<ffffffff81112c67>] ? mempool_free_slab+0x17/0x20
 [<ffffffff8119f2b1>] ? bio_free+0x61/0x70
 [<ffffffff811adece>] ? aio_kernel_free+0xe/0x10
 [<ffffffff811adb1e>] aio_write_iter+0x2e/0x30

Fix this by avoiding the second call to ocfs2_refcount_tree_put()

Signed-off-by: Ashish Samant <ashish.samant@oracle.com>
Reviewed-by: Eric Ren <zren@suse.com>
Acked-by: Srinivas Eeda <srinivas.eeda@oracle.com>