ocfs2: ac_bits_wanted should be local_alloc_bits when returns -ENOSPC

There is an issue in reserving and claiming space for localalloc, When
localalloc space is not enough, it would claim space from global_bitmap.
And if there is not enough free space in global_bitmap, the size of
claiming space would set to half of orignal size and retry.

The issue is as follows: osb->local_alloc_bits is set to half of orignal
size in ocfs2_recalc_la_window(), but ac->ac_bits_wanted is set to
osb->local_alloc_default_bits which is not changed.  localalloc always
reserves and claims local_alloc_default_bits space and returns ENOSPC.

So, ac->ac_bits_wanted should be osb->local_alloc_bits which would be
changed.

Signed-off-by: Younger Liu <younger.liu@huawei.com>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Mark Fasheh <mfasheh@suse.com>
Cc: Jeff Liu <jeff.liu@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>