Btrfs: fix a bug in parsing return value in logical resolve

In logical resolve, we parse extent_from_logical()'s 'ret' as a kind of flag.

It is possible to lose our errors because
(-EXXXX & BTRFS_EXTENT_FLAG_TREE_BLOCK) is true.

I'm not sure if it is on purpose, it just looks too hacky if it is.
I'd rather use a real flag and a 'ret' to catch errors.
Acked-by: NJan Schmidt <list.btrfs@jan-o-sch.net>
Signed-off-by: NLiu Bo <liub.liubo@gmail.com>

fs/btrfs/backref.c

@@ -1193,7 +1193,8 @@ char *btrfs_iref_to_path(struct btrfs_root *fs_root, struct btrfs_path *path,
  * tree blocks and <0 on error.
  */
 int extent_from_logical(struct btrfs_fs_info *fs_info, u64 logical,
-			struct btrfs_path *path, struct btrfs_key *found_key)
+			struct btrfs_path *path, struct btrfs_key *found_key,
+			u64 *flags_ret)
 {
 	int ret;
 	u64 flags;
@@ -1237,10 +1238,17 @@ int extent_from_logical(struct btrfs_fs_info *fs_info, u64 logical,
 		 (unsigned long long)found_key->objectid,
 		 (unsigned long long)found_key->offset,
 		 (unsigned long long)flags, item_size);
+
+	WARN_ON(!flags_ret);
+	if (flags_ret) {
 		if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK)
-		return BTRFS_EXTENT_FLAG_TREE_BLOCK;
-	if (flags & BTRFS_EXTENT_FLAG_DATA)
-		return BTRFS_EXTENT_FLAG_DATA;
+			*flags_ret = BTRFS_EXTENT_FLAG_TREE_BLOCK;
+		else if (flags & BTRFS_EXTENT_FLAG_DATA)
+			*flags_ret = BTRFS_EXTENT_FLAG_DATA;
+		else
+			BUG_ON(1);
+		return 0;
+	}
 
 	return -EIO;
 }
@@ -1433,15 +1441,15 @@ int iterate_inodes_from_logical(u64 logical, struct btrfs_fs_info *fs_info,
 {
 	int ret;
 	u64 extent_item_pos;
+	u64 flags = 0;
 	struct btrfs_key found_key;
 	int search_commit_root = path->search_commit_root;
 
-	ret = extent_from_logical(fs_info, logical, path,
-					&found_key);
+	ret = extent_from_logical(fs_info, logical, path, &found_key, &flags);
 	btrfs_release_path(path);
 	if (ret < 0)
 		return ret;
-	if (ret & BTRFS_EXTENT_FLAG_TREE_BLOCK)
+	if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK)
 		return -EINVAL;
 
 	extent_item_pos = logical - found_key.objectid;

fs/btrfs/backref.h

@@ -40,7 +40,8 @@ int inode_item_info(u64 inum, u64 ioff, struct btrfs_root *fs_root,
 			struct btrfs_path *path);
 
 int extent_from_logical(struct btrfs_fs_info *fs_info, u64 logical,
-			struct btrfs_path *path, struct btrfs_key *found_key);
+			struct btrfs_path *path, struct btrfs_key *found_key,
+			u64 *flags);
 
 int tree_backref_for_extent(unsigned long *ptr, struct extent_buffer *eb,
 				struct btrfs_extent_item *ei, u32 item_size,

fs/btrfs/ioctl.c

@@ -3211,6 +3211,7 @@ static long btrfs_ioctl_logical_to_ino(struct btrfs_root *root,
 	int ret = 0;
 	int size;
 	u64 extent_item_pos;
+	u64 flags = 0;
 	struct btrfs_ioctl_logical_ino_args *loi;
 	struct btrfs_data_container *inodes = NULL;
 	struct btrfs_path *path = NULL;
@@ -3240,10 +3241,11 @@ static long btrfs_ioctl_logical_to_ino(struct btrfs_root *root,
 		goto out;
 	}
 
-	ret = extent_from_logical(root->fs_info, loi->logical, path, &key);
+	ret = extent_from_logical(root->fs_info, loi->logical, path, &key,
+				  &flags);
 	btrfs_release_path(path);
 
-	if (ret & BTRFS_EXTENT_FLAG_TREE_BLOCK)
+	if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK)
 		ret = -ENOENT;
 	if (ret < 0)
 		goto out;

fs/btrfs/scrub.c

@@ -352,13 +352,14 @@ static void scrub_print_warning(const char *errstr, struct scrub_block *sblock)
 	struct extent_buffer *eb;
 	struct btrfs_extent_item *ei;
 	struct scrub_warning swarn;
-	u32 item_size;
-	int ret;
+	unsigned long ptr = 0;
+	u64 extent_item_pos;
+	u64 flags = 0;
 	u64 ref_root;
+	u32 item_size;
 	u8 ref_level;
-	unsigned long ptr = 0;
 	const int bufsize = 4096;
-	u64 extent_item_pos;
+	int ret;
 
 	path = btrfs_alloc_path();
 
@@ -375,7 +376,8 @@ static void scrub_print_warning(const char *errstr, struct scrub_block *sblock)
 	if (!path || !swarn.scratch_buf || !swarn.msg_buf)
 		goto out;
 
-	ret = extent_from_logical(fs_info, swarn.logical, path, &found_key);
+	ret = extent_from_logical(fs_info, swarn.logical, path, &found_key,
+				  &flags);
 	if (ret < 0)
 		goto out;
 
@@ -387,7 +389,7 @@ static void scrub_print_warning(const char *errstr, struct scrub_block *sblock)
 	item_size = btrfs_item_size_nr(eb, path->slots[0]);
 	btrfs_release_path(path);
 
-	if (ret & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
+	if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
 		do {
 			ret = tree_backref_for_extent(&ptr, eb, ei, item_size,
 							&ref_root, &ref_level);

fs/btrfs/send.c

@@ -1152,6 +1152,7 @@ static int find_extent_clone(struct send_ctx *sctx,
 	u64 disk_byte;
 	u64 num_bytes;
 	u64 extent_item_pos;
+	u64 flags = 0;
 	struct btrfs_file_extent_item *fi;
 	struct extent_buffer *eb = path->nodes[0];
 	struct backref_ctx *backref_ctx = NULL;
@@ -1198,13 +1199,13 @@ static int find_extent_clone(struct send_ctx *sctx,
 	}
 	logical = disk_byte + btrfs_file_extent_offset(eb, fi);
 
-	ret = extent_from_logical(sctx->send_root->fs_info,
-			disk_byte, tmp_path, &found_key);
+	ret = extent_from_logical(sctx->send_root->fs_info, disk_byte, tmp_path,
+				  &found_key, &flags);
 	btrfs_release_path(tmp_path);
 
 	if (ret < 0)
 		goto out;
-	if (ret & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
+	if (flags & BTRFS_EXTENT_FLAG_TREE_BLOCK) {
 		ret = -EIO;
 		goto out;
 	}