btrfs: document existence of extent_io ops callbacks
Some of the callbacks defined in btree_extent_io_ops and
btrfs_extent_io_ops do always exist so we don't need to check the
existence before each call. This patch just reorders the definition and
documents which are mandatory/optional.
Signed-off-by: David Sterba <dsterba@suse.com>
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 67d663a..60d4f1b 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -4653,9 +4653,12 @@ static int btrfs_cleanup_transaction(struct btrfs_fs_info *fs_info)
}
static const struct extent_io_ops btree_extent_io_ops = {
- .readpage_end_io_hook = btree_readpage_end_io_hook,
- .readpage_io_failed_hook = btree_io_failed_hook,
+ /* mandatory callbacks */
.submit_bio_hook = btree_submit_bio_hook,
+ .readpage_end_io_hook = btree_readpage_end_io_hook,
/* note we're sharing with inode.c for the merge bio hook */
.merge_bio_hook = btrfs_merge_bio_hook,
+
+ /* optional callbacks */
+ .readpage_io_failed_hook = btree_io_failed_hook,
};