ocfs2: adjust enabling place for la window

ocfs2: adjust enabling place for la window

Patch series "improve write IO performance when fragmentation is high",
v6.

This patch (of 4):

After introducing gd->bg_contig_free_bits, the code path
'ocfs2_cluster_group_search() => ocfs2_local_alloc_seen_free_bits()'
becomes death when all the gd->bg_contig_free_bits are set to the correct
value.  This patch relocates ocfs2_local_alloc_seen_free_bits() to a more
appropriate location.  (The new place being ocfs2_block_group_set_bits().)

In ocfs2_local_alloc_seen_free_bits(), the scope of the spin-lock has been
adjusted to reduce meaningless lock races.  e.g: when userspace creates &
deletes 1 cluster_size files in parallel, acquiring the spin-lock in
ocfs2_local_alloc_seen_free_bits() is totally pointless and impedes IO
performance.

Link: https://lkml.kernel.org/r/20240328125203.20892-3-heming.zhao@suse.com
Signed-off-by: Heming Zhao <heming.zhao@suse.com>
Reviewed-by: Joseph Qi <joseph.qi@linux.alibaba.com>
Cc: Mark Fasheh <mark@fasheh.com>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Junxiao Bi <junxiao.bi@oracle.com>
Cc: Changwei Ge <gechangwei@live.cn>
Cc: Gang He <ghe@suse.com>
Cc: Jun Piao <piaojun@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>