[PATCH 4.14 40/43] ext4: find old entry again if failed to rename whiteout

[Greg Kroah-Hartman]

From: zhangyi (F) <yi.zh...@huawei.com>

commit b7ff91fd030dc9d72ed91b1aab36e445a003af4f upstream.

If we failed to add new entry on rename whiteout, we cannot reset the
old->de entry directly, because the old->de could have moved from under
us during make indexed dir. So find the old entry again before reset is
needed, otherwise it may corrupt the filesystem as below.

  /dev/sda: Entry '00000001' in ??? (12) has deleted/unused inode 15. CLEARED.
  /dev/sda: Unattached inode 75
  /dev/sda: UNEXPECTED INCONSISTENCY; RUN fsck MANUALLY.

Fixes: 6b4b8e6b4ad ("ext4: fix bug for rename with RENAME_WHITEOUT")
Cc: sta...@vger.kernel.org
Signed-off-by: zhangyi (F) <yi.zh...@huawei.com>
Link: https://lore.kernel.org/r/20210303131703.330415-1-yi.zh...@huawei.com
Signed-off-by: Theodore Ts'o <ty...@mit.edu>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>
---
 fs/ext4/namei.c |   29 +++++++++++++++++++++++++++--
 1 file changed, 27 insertions(+), 2 deletions(-)

--- a/fs/ext4/namei.c
+++ b/fs/ext4/namei.c
@@ -3445,6 +3445,31 @@ static int ext4_setent(handle_t *handle,
        return 0;
 }
 
+static void ext4_resetent(handle_t *handle, struct ext4_renament *ent,
+                         unsigned ino, unsigned file_type)
+{
+       struct ext4_renament old = *ent;
+       int retval = 0;
+
+       /*
+        * old->de could have moved from under us during make indexed dir,
+        * so the old->de may no longer valid and need to find it again
+        * before reset old inode info.
+        */
+       old.bh = ext4_find_entry(old.dir, &old.dentry->d_name, &old.de, NULL);
+       if (IS_ERR(old.bh))
+               retval = PTR_ERR(old.bh);
+       if (!old.bh)
+               retval = -ENOENT;
+       if (retval) {
+               ext4_std_error(old.dir->i_sb, retval);
+               return;
+       }
+
+       ext4_setent(handle, &old, ino, file_type);
+       brelse(old.bh);
+}
+
 static int ext4_find_delete_entry(handle_t *handle, struct inode *dir,
                                  const struct qstr *d_name)
 {
@@ -3754,8 +3779,8 @@ static int ext4_rename(struct inode *old
 end_rename:
        if (whiteout) {
                if (retval) {
-                       ext4_setent(handle, &old,
-                               old.inode->i_ino, old_file_type);
+                       ext4_resetent(handle, &old,
+                                     old.inode->i_ino, old_file_type);
                        drop_nlink(whiteout);
                }
                unlock_new_inode(whiteout);