btrfs: preallocate radix tree node for readahead
We can preallocate the node so insertion does not have to do that under
the lock. The GFP flags for the per-device radix tree are initialized to
GFP_NOFS & ~__GFP_DIRECT_RECLAIM
but we can use GFP_KERNEL, same as an allocation above anyway, but also
because readahead is optional and not on any critical writeout path.
Reviewed-by: Liu Bo <bo.li.liu@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>
diff --git a/fs/btrfs/reada.c b/fs/btrfs/reada.c
index e88bca8..fdae8ca 100644
--- a/fs/btrfs/reada.c
+++ b/fs/btrfs/reada.c
@@ -270,6 +270,12 @@ static struct reada_zone *reada_find_zone(struct btrfs_fs_info *fs_info,
if (!zone)
return NULL;
+ ret = radix_tree_preload(GFP_KERNEL);
+ if (ret) {
+ kfree(zone);
+ return NULL;
+ }
+
zone->start = start;
zone->end = end;
INIT_LIST_HEAD(&zone->list);
@@ -299,6 +305,7 @@ static struct reada_zone *reada_find_zone(struct btrfs_fs_info *fs_info,
zone = NULL;
}
spin_unlock(&fs_info->reada_lock);
+ radix_tree_preload_end();
return zone;
}
