Btrfs: fix an oops of log replay

When btrfs recovers from a crash, it may hit the oops below:

------------[ cut here ]------------
kernel BUG at fs/btrfs/inode.c:4580!
[...]
RIP: 0010:[<ffffffffa03df251>]  [<ffffffffa03df251>] btrfs_add_link+0x161/0x1c0 [btrfs]
[...]
Call Trace:
 [<ffffffffa03e7b31>] ? btrfs_inode_ref_index+0x31/0x80 [btrfs]
 [<ffffffffa04054e9>] add_inode_ref+0x319/0x3f0 [btrfs]
 [<ffffffffa0407087>] replay_one_buffer+0x2c7/0x390 [btrfs]
 [<ffffffffa040444a>] walk_down_log_tree+0x32a/0x480 [btrfs]
 [<ffffffffa0404695>] walk_log_tree+0xf5/0x240 [btrfs]
 [<ffffffffa0406cc0>] btrfs_recover_log_trees+0x250/0x350 [btrfs]
 [<ffffffffa0406dc0>] ? btrfs_recover_log_trees+0x350/0x350 [btrfs]
 [<ffffffffa03d18b2>] open_ctree+0x1442/0x17d0 [btrfs]
[...]

This comes from that while replaying an inode ref item, we forget to
check those old conflicting DIR_ITEM and DIR_INDEX items in fs/file tree,
then we will come to conflict corners which lead to BUG_ON().

Signed-off-by: Liu Bo <liubo2009@cn.fujitsu.com>
Tested-by: Andy Lutomirski <luto@mit.edu>
Signed-off-by: Chris Mason <chris.mason@oracle.com>

1 files changed, 24 insertions, 4 deletions

diff --git a/fs/btrfs/tree-log.c b/fs/btrfs/tree-log.c
index babee65f8eda..786639fca067 100644
--- a/fs/btrfs/tree-log.c
+++ b/fs/btrfs/tree-log.c
@@ -799,14 +799,15 @@ static noinline int add_inode_ref(struct btrfs_trans_handle *trans,
                                   struct extent_buffer *eb, int slot,
                                   struct btrfs_key *key)
 {
-        struct inode *dir;
-        int ret;
         struct btrfs_inode_ref *ref;
+        struct btrfs_dir_item *di;
+        struct inode *dir;
         struct inode *inode;
-        char *name;
-        int namelen;
         unsigned long ref_ptr;
         unsigned long ref_end;
+        char *name;
+        int namelen;
+        int ret;
         int search_done = 0;
 
         /*
@@ -909,6 +910,25 @@ again:
         }
         btrfs_release_path(path);
 
+        /* look for a conflicting sequence number */
+        di = btrfs_lookup_dir_index_item(trans, root, path, btrfs_ino(dir),
+                                         btrfs_inode_ref_index(eb, ref),
+                                         name, namelen, 0);
+        if (di && !IS_ERR(di)) {
+                ret = drop_one_dir_item(trans, root, path, dir, di);
+                BUG_ON(ret);
+        }
+        btrfs_release_path(path);
+
+        /* look for a conflicing name */
+        di = btrfs_lookup_dir_item(trans, root, path, btrfs_ino(dir),
+                                   name, namelen, 0);
+        if (di && !IS_ERR(di)) {
+                ret = drop_one_dir_item(trans, root, path, dir, di);
+                BUG_ON(ret);
+        }
+        btrfs_release_path(path);
+
 insert:
         /* insert our name */
         ret = btrfs_add_link(trans, dir, inode, name, namelen, 0,