ocfs2: fix clusters leak in ocfs2_defrag_extent()

ocfs2: fix clusters leak in ocfs2_defrag_extent()

[ Upstream commit 6194ae4242dec0c9d604bc05df83aa9260a899e4 ]

ocfs2_defrag_extent() might leak allocated clusters.  When the file
system has insufficient space, the number of claimed clusters might be
less than the caller wants.  If that happens, the original code might
directly commit the transaction without returning clusters.

This patch is based on code in ocfs2_add_clusters_in_btree().

[akpm@linux-foundation.org: include localalloc.h, reduce scope of data_ac]
Link: http://lkml.kernel.org/r/20180904041621.16874-3-lchen@suse.com
Signed-off-by: Larry Chen <lchen@suse.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Mark Fasheh <mark@fasheh.com>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Junxiao Bi <junxiao.bi@oracle.com>
Cc: Joseph Qi <jiangqi903@gmail.com>
Cc: Changwei Ge <ge.changwei@h3c.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>