btrfs: send: directly return from will_overwrite_ref() and simplify it

There are no resources to release before will_overwrite_ref() returns, so
we don't really need the 'out' label and jumping to it when conditions are
met - we can directly return and get rid of the label and jumps. Also we
can deal with -ENOENT and other errors in a single if-else logic, as it's
more straightforward.

This helps the next patch in the series to be more simple as well.

This patch is part of a larger patchset and the changelog of the last
patch in the series contains a sample performance test and results.
The patches that comprise the patchset are the following:

  btrfs: send: directly return from did_overwrite_ref() and simplify it
  btrfs: send: avoid unnecessary generation search at did_overwrite_ref()
  btrfs: send: directly return from will_overwrite_ref() and simplify it
  btrfs: send: avoid extra b+tree searches when checking reference overrides
  btrfs: send: remove send_progress argument from can_rmdir()
  btrfs: send: avoid duplicated orphan dir allocation and initialization
  btrfs: send: avoid unnecessary orphan dir rbtree search at can_rmdir()
  btrfs: send: reduce searches on parent root when checking if dir can be removed
  btrfs: send: iterate waiting dir move rbtree only once when processing refs
  btrfs: send: initialize all the red black trees earlier
  btrfs: send: genericize the backref cache to allow it to be reused
  btrfs: adapt lru cache to allow for 64 bits keys on 32 bits systems
  btrfs: send: cache information about created directories
  btrfs: allow a generation number to be associated with lru cache entries
  btrfs: add an api to delete a specific entry from the lru cache
  btrfs: send: use the lru cache to implement the name cache
  btrfs: send: update size of roots array for backref cache entries
  btrfs: send: cache utimes operations for directories if possible
Signed-off-by: NFilipe Manana <fdmanana@suse.com>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

fs/btrfs/send.c

@@ -2119,17 +2119,17 @@ static int will_overwrite_ref(struct send_ctx *sctx, u64 dir, u64 dir_gen,
 			      const char *name, int name_len,
 			      u64 *who_ino, u64 *who_gen, u64 *who_mode)
 {
-	int ret = 0;
+	int ret;
 	u64 gen;
 	u64 other_inode = 0;
 	struct btrfs_inode_info info;
 
 	if (!sctx->parent_root)
-		goto out;
+		return 0;
 
 	ret = is_inode_existent(sctx, dir, dir_gen);
 	if (ret <= 0)
-		goto out;
+		return 0;
 
 	/*
 	 * If we have a parent root we need to verify that the parent dir was
@@ -2138,24 +2138,21 @@ static int will_overwrite_ref(struct send_ctx *sctx, u64 dir, u64 dir_gen,
 	 */
 	if (sctx->parent_root && dir != BTRFS_FIRST_FREE_OBJECTID) {
 		ret = get_inode_gen(sctx->parent_root, dir, &gen);
-		if (ret < 0 && ret != -ENOENT)
-			goto out;
-		if (ret) {
-			ret = 0;
-			goto out;
-		}
+		if (ret == -ENOENT)
+			return 0;
+		else if (ret < 0)
+			return ret;
+
 		if (gen != dir_gen)
-			goto out;
+			return 0;
 	}
 
 	ret = lookup_dir_item_inode(sctx->parent_root, dir, name, name_len,
 				    &other_inode);
-	if (ret < 0 && ret != -ENOENT)
-		goto out;
-	if (ret) {
-		ret = 0;
-		goto out;
-	}
+	if (ret == -ENOENT)
+		return 0;
+	else if (ret < 0)
+		return ret;
 
 	/*
 	 * Check if the overwritten ref was already processed. If yes, the ref
@@ -2166,18 +2163,15 @@ static int will_overwrite_ref(struct send_ctx *sctx, u64 dir, u64 dir_gen,
 	    is_waiting_for_move(sctx, other_inode)) {
 		ret = get_inode_info(sctx->parent_root, other_inode, &info);
 		if (ret < 0)
-			goto out;
+			return ret;
 
-		ret = 1;
 		*who_ino = other_inode;
 		*who_gen = info.gen;
 		*who_mode = info.mode;
-	} else {
-		ret = 0;
+		return 1;
 	}
 
-out:
-	return ret;
+	return 0;
 }
 
 /*