[PATCH] btrfs: inode: Check if we get a valid inode before checking its mode.

[Qu Wenruo <wqu@suse.com>]

We should check the inode validation before checking the imode.

As btrfs_iget() could return ERR_PTR(), unlike previous path, we need to
verify the inode before checking the imode.

Signed-off-by: Qu Wenruo <wqu@suse.com>
---
To David:

Please fold this into 9944a5b5d26e ("btrfs: inode: Verify inode mode to avoid NULL pointer dereference") 
of misc-next branch.
---
 fs/btrfs/inode.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 3ee835cbb490..97f47dd295e8 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -5776,6 +5776,8 @@ struct inode *btrfs_lookup_dentry(struct inode *dir, struct dentry *dentry)
 
 	if (location.type == BTRFS_INODE_ITEM_KEY) {
 		inode = btrfs_iget(dir->i_sb, &location, root, NULL);
+		if (IS_ERR(inode))
+			return inode;
 
 		/* Do extra check against inode mode with di_type */
 		if (btrfs_inode_type(inode) != di_type) {
-- 
2.21.0