Btrfs: Fix .. lookup corner case

Inode ref item can be in the next leaf when we find "path->slots[0] ==
btrfs_header_nritems(...)".

Signed-off-by: Chris Mason <chris.mason@oracle.com>

1 files changed, 9 insertions, 13 deletions

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 8bc981c4f5ef..cf9534b79aba 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -1752,21 +1752,18 @@ static int btrfs_inode_by_name(struct inode *dir, struct dentry *dentry,
         if (namelen == 2 && strcmp(name, "..") == 0) {
                 struct btrfs_key key;
                 struct extent_buffer *leaf;
-                u32 nritems;
                 int slot;
 
                 key.objectid = dir->i_ino;
+                key.offset = (u64)-1;
                 btrfs_set_key_type(&key, BTRFS_INODE_REF_KEY);
-                key.offset = 0;
+                if (ret < 0 || path->slots[0] == 0)
+                        goto out_err;
                 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
                 BUG_ON(ret == 0);
                 ret = 0;
-
                 leaf = path->nodes[0];
-                slot = path->slots[0];
-                nritems = btrfs_header_nritems(leaf);
-                if (slot >= nritems)
-                        goto out_err;
+                slot = path->slots[0] - 1;
 
                 btrfs_item_key_to_cpu(leaf, &key, slot);
                 if (key.objectid != dir->i_ino ||
@@ -1980,16 +1977,15 @@ static int btrfs_readdir(struct file *filp, void *dirent, filldir_t filldir)
         /* special case for .., just use the back ref */
         if (filp->f_pos == 1) {
                 btrfs_set_key_type(&key, BTRFS_INODE_REF_KEY);
-                key.offset = 0;
+                key.offset = (u64)-1;
                 ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
-                BUG_ON(ret == 0);
-                leaf = path->nodes[0];
-                slot = path->slots[0];
-                nritems = btrfs_header_nritems(leaf);
-                if (slot >= nritems) {
+                if (ret < 0 || path->slots[0] == 0) {
                         btrfs_release_path(root, path);
                         goto read_dir_items;
                 }
+                BUG_ON(ret == 0);
+                leaf = path->nodes[0];
+                slot = path->slots[0] - 1;
                 btrfs_item_key_to_cpu(leaf, &found_key, slot);
                 btrfs_release_path(root, path);
                 if (found_key.objectid != key.objectid ||