btrfs: fix dereference before check
The superblock's ->s_fs_info is properly set in btrfs_fill_super, after
a call to open_ctree, which derefereces it before check. Although
tree_root is set via btrfs_set_super, let's be defensive and leave the
check in place.
Signed-off-by: David Sterba <dsterba@suse.cz>
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 990afa8..25e4b8f 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -1611,7 +1611,7 @@
struct btrfs_root *csum_root = kzalloc(sizeof(struct btrfs_root),
GFP_NOFS);
struct btrfs_root *tree_root = btrfs_sb(sb);
- struct btrfs_fs_info *fs_info = tree_root->fs_info;
+ struct btrfs_fs_info *fs_info = NULL;
struct btrfs_root *chunk_root = kzalloc(sizeof(struct btrfs_root),
GFP_NOFS);
struct btrfs_root *dev_root = kzalloc(sizeof(struct btrfs_root),
@@ -1623,11 +1623,12 @@
struct btrfs_super_block *disk_super;
- if (!extent_root || !tree_root || !fs_info ||
+ if (!extent_root || !tree_root || !tree_root->fs_info ||
!chunk_root || !dev_root || !csum_root) {
err = -ENOMEM;
goto fail;
}
+ fs_info = tree_root->fs_info;
ret = init_srcu_struct(&fs_info->subvol_srcu);
if (ret) {