btrfs: use a single variable for return value at lookup_inline_extent_backref()

At lookup_inline_extent_backref(), instead of using a 'ret' and an 'err'
variable for tracking the return value, use a single one ('ret'). This
simplifies the code, makes it comply with most of the existing code and
it's less prone for logic errors as time has proven over and over in the
btrfs code.
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/extent-tree.c

@@ -789,7 +789,6 @@ int lookup_inline_extent_backref(struct btrfs_trans_handle *trans,
 	int type;
 	int want;
 	int ret;
-	int err = 0;
 	bool skinny_metadata = btrfs_fs_incompat(fs_info, SKINNY_METADATA);
 	int needed;
 
@@ -816,10 +815,8 @@ int lookup_inline_extent_backref(struct btrfs_trans_handle *trans,
 
 again:
 	ret = btrfs_search_slot(trans, root, &key, path, extra_size, 1);
-	if (ret < 0) {
-		err = ret;
+	if (ret < 0)
 		goto out;
-	}
 
 	/*
 	 * We may be a newly converted file system which still has the old fat
@@ -846,7 +843,7 @@ int lookup_inline_extent_backref(struct btrfs_trans_handle *trans,
 	}
 
 	if (ret && !insert) {
-		err = -ENOENT;
+		ret = -ENOENT;
 		goto out;
 	} else if (WARN_ON(ret)) {
 		btrfs_print_leaf(path->nodes[0]);
@@ -854,18 +851,18 @@ int lookup_inline_extent_backref(struct btrfs_trans_handle *trans,
 "extent item not found for insert, bytenr %llu num_bytes %llu parent %llu root_objectid %llu owner %llu offset %llu",
 			  bytenr, num_bytes, parent, root_objectid, owner,
 			  offset);
-		err = -EIO;
+		ret = -EIO;
 		goto out;
 	}
 
 	leaf = path->nodes[0];
 	item_size = btrfs_item_size(leaf, path->slots[0]);
 	if (unlikely(item_size < sizeof(*ei))) {
-		err = -EUCLEAN;
+		ret = -EUCLEAN;
 		btrfs_err(fs_info,
 			  "unexpected extent item size, has %llu expect >= %zu",
 			  item_size, sizeof(*ei));
-		btrfs_abort_transaction(trans, err);
+		btrfs_abort_transaction(trans, ret);
 		goto out;
 	}
 
@@ -885,11 +882,11 @@ int lookup_inline_extent_backref(struct btrfs_trans_handle *trans,
 	else
 		needed = BTRFS_REF_TYPE_BLOCK;
 
-	err = -ENOENT;
+	ret = -ENOENT;
 	while (1) {
 		if (ptr >= end) {
 			if (ptr > end) {
-				err = -EUCLEAN;
+				ret = -EUCLEAN;
 				btrfs_print_leaf(path->nodes[0]);
 				btrfs_crit(fs_info,
 "overrun extent record at slot %d while looking for inline extent for root %llu owner %llu offset %llu parent %llu",
@@ -900,7 +897,7 @@ int lookup_inline_extent_backref(struct btrfs_trans_handle *trans,
 		iref = (struct btrfs_extent_inline_ref *)ptr;
 		type = btrfs_get_extent_inline_ref_type(leaf, iref, needed);
 		if (type == BTRFS_REF_TYPE_INVALID) {
-			err = -EUCLEAN;
+			ret = -EUCLEAN;
 			goto out;
 		}
 
@@ -916,7 +913,7 @@ int lookup_inline_extent_backref(struct btrfs_trans_handle *trans,
 			dref = (struct btrfs_extent_data_ref *)(&iref->offset);
 			if (match_extent_data_ref(leaf, dref, root_objectid,
 						  owner, offset)) {
-				err = 0;
+				ret = 0;
 				break;
 			}
 			if (hash_extent_data_ref_item(leaf, dref) <
@@ -927,14 +924,14 @@ int lookup_inline_extent_backref(struct btrfs_trans_handle *trans,
 			ref_offset = btrfs_extent_inline_ref_offset(leaf, iref);
 			if (parent > 0) {
 				if (parent == ref_offset) {
-					err = 0;
+					ret = 0;
 					break;
 				}
 				if (ref_offset < parent)
 					break;
 			} else {
 				if (root_objectid == ref_offset) {
-					err = 0;
+					ret = 0;
 					break;
 				}
 				if (ref_offset < root_objectid)
@@ -943,10 +940,10 @@ int lookup_inline_extent_backref(struct btrfs_trans_handle *trans,
 		}
 		ptr += btrfs_extent_inline_ref_size(type);
 	}
-	if (err == -ENOENT && insert) {
+	if (ret == -ENOENT && insert) {
 		if (item_size + extra_size >=
 		    BTRFS_MAX_EXTENT_ITEM_SIZE(root)) {
-			err = -EAGAIN;
+			ret = -EAGAIN;
 			goto out;
 		}
 		/*
@@ -958,7 +955,7 @@ int lookup_inline_extent_backref(struct btrfs_trans_handle *trans,
 		if (find_next_key(path, 0, &key) == 0 &&
 		    key.objectid == bytenr &&
 		    key.type < BTRFS_BLOCK_GROUP_ITEM_KEY) {
-			err = -EAGAIN;
+			ret = -EAGAIN;
 			goto out;
 		}
 	}
@@ -969,7 +966,7 @@ int lookup_inline_extent_backref(struct btrfs_trans_handle *trans,
 		path->search_for_extension = 0;
 		btrfs_unlock_up_safe(path, 1);
 	}
-	return err;
+	return ret;
 }
 
 /*