reiserfs: make commit_wq use the default concurrency level

The maximum number of concurrent work items queued on commit_wq is
bound by the number of active journals.  Convert to alloc_workqueue()
and use the default concurrency level so that they can be processed in
parallel.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: reiserfs-devel@vger.kernel.org

fs/reiserfs/journal.c

@@ -2876,7 +2876,7 @@ int journal_init(struct super_block *sb, const char *j_dev_name,
 	reiserfs_mounted_fs_count++;
 	if (reiserfs_mounted_fs_count <= 1) {
 		reiserfs_write_unlock(sb);
-		commit_wq = create_workqueue("reiserfs");
+		commit_wq = alloc_workqueue("reiserfs", WQ_MEM_RECLAIM, 0);
 		reiserfs_write_lock(sb);
 	}