[PATCH] btrfs: Rework error detection in init_tree_roots

[Nikolay Borisov <nborisov@suse.com>]

To avoid duplicating 3 lines of code the error detection logic in
init_tree_roots is somewhat quirky. It first checks for the presence of
any error condition, then checks for the specific condition to perform
any specific actions. That's spurious because directly checking for
each respective error condition and doing the necessary steps is more
obvious. Additionally it results in smaller code and the code reads
more linearly:

add/remove: 0/0 grow/shrink: 0/1 up/down: 0/-95 (-95)
Function                                     old     new   delta
open_ctree                                 17243   17148     -95
Total: Before=113104, After=113009, chg -0.08%

Signed-off-by: Nikolay Borisov <nborisov@suse.com>
---
 fs/btrfs/disk-io.c | 17 ++++++++---------
 1 file changed, 8 insertions(+), 9 deletions(-)

diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 5fc5f62228f1..ecb8ca53244f 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -2645,17 +2645,16 @@ static int __cold init_tree_roots(struct btrfs_fs_info *fs_info)
 		level = btrfs_super_root_level(sb);
 		tree_root->node = read_tree_block(fs_info, btrfs_super_root(sb),
 						  generation, level, NULL);
-		if (IS_ERR(tree_root->node) ||
-		    !extent_buffer_uptodate(tree_root->node)) {
+		if (IS_ERR(tree_root->node)) {
 			handle_error = true;
+			ret = PTR_ERR(tree_root->node);
+			tree_root->node = NULL;
+			btrfs_warn(fs_info, "failed to read tree root");
+			continue;
 
-			if (IS_ERR(tree_root->node)) {
-				ret = PTR_ERR(tree_root->node);
-				tree_root->node = NULL;
-			} else if (!extent_buffer_uptodate(tree_root->node)) {
-				ret = -EUCLEAN;
-			}
-
+		} else if (!extent_buffer_uptodate(tree_root->node)) {
+			handle_error = true;
+			ret = -EUCLEAN;
 			btrfs_warn(fs_info, "failed to read tree root");
 			continue;
 		}
-- 
2.17.1