Btrfs-progs: fsck: fix wrong check for btrfs_read_fs_root()

When encountering a corrupted fs root node, fsck hit following message:

Check tree block failed, want=29360128, have=0
Check tree block failed, want=29360128, have=0
Check tree block failed, want=29360128, have=0
Check tree block failed, want=29360128, have=0
Check tree block failed, want=29360128, have=0
read block failed check_tree_block
Checking filesystem on /dev/sda9
UUID: 0d295d80-bae2-45f2-a106-120dbfd0e173
checking extents
Segmentation fault (core dumped)

This is because in btrfs_setup_all_roots(), we check
btrfs_read_fs_root() return value by verifing whether it is
NULL pointer, this is wrong since btrfs_read_fs_root() return
PTR_ERR(ret), fix it.

Signed-off-by: Wang Shilong <wangsl.fnst@cn.fujitsu.com>
Signed-off-by: David Sterba <dsterba@suse.cz>

2 files changed, 2 insertions, 2 deletions

diff --git a/btrfs-calc-size.c b/btrfs-calc-size.c
index a832ee0b..5eabdfc2 100644
--- a/btrfs-calc-size.c
+++ b/btrfs-calc-size.c
@@ -326,7 +326,7 @@ static int calc_root_size(struct btrfs_root *tree_root, struct btrfs_key *key,
 	int size_fail = 0;
 
 	root = btrfs_read_fs_root(tree_root->fs_info, key);
-	if (!root) {
+	if (IS_ERR(root)) {
 		fprintf(stderr, "Failed to read root %Lu\n", key->objectid);
 		return 1;
 	}
diff --git a/disk-io.c b/disk-io.c
index 58f3f07c..a54025e7 100644
--- a/disk-io.c
+++ b/disk-io.c
@@ -939,7 +939,7 @@ int btrfs_setup_all_roots(struct btrfs_fs_info *fs_info, u64 root_tree_bytenr,
 	key.offset = (u64)-1;
 	fs_info->fs_root = btrfs_read_fs_root(fs_info, &key);
 
-	if (!fs_info->fs_root)
+	if (IS_ERR(fs_info->fs_root))
 		return -EIO;
 	return 0;
 }