diff options
authorTheodore Ts'o <tytso@mit.edu>2019-11-11 22:18:13 -0500
committerPaul Gortmaker <paul.gortmaker@windriver.com>2020-01-31 16:51:03 -0500
commita9b6310e93a4012fffacc2699f5ea0c125f4bf00 (patch)
parent609a4e56145d7d9b52db8f8ed3343b7f5563f20a (diff)
ext4: work around deleting a file with i_nlink == 0 safely
commit c7df4a1ecb8579838ec8c56b2bb6a6716e974f37 upstream. If the file system is corrupted such that a file's i_links_count is too small, then it's possible that when unlinking that file, i_nlink will already be zero. Previously we were working around this kind of corruption by forcing i_nlink to one; but we were doing this before trying to delete the directory entry --- and if the file system is corrupted enough that ext4_delete_entry() fails, then we exit with i_nlink elevated, and this causes the orphan inode list handling to be FUBAR'ed, such that when we unmount the file system, the orphan inode list can get corrupted. A better way to fix this is to simply skip trying to call drop_nlink() if i_nlink is already zero, thus moving the check to the place where it makes the most sense. https://bugzilla.kernel.org/show_bug.cgi?id=205433 Link: https://lore.kernel.org/r/20191112032903.8828-1-tytso@mit.edu Signed-off-by: Theodore Ts'o <tytso@mit.edu> Cc: stable@kernel.org Reviewed-by: Andreas Dilger <adilger@dilger.ca> Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
1 files changed, 5 insertions, 6 deletions
diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c
index 771fe02f317d..447974a4fe66 100644
--- a/fs/ext4/namei.c
+++ b/fs/ext4/namei.c
@@ -3158,18 +3158,17 @@ static int ext4_unlink(struct inode *dir, struct dentry *dentry)
if (IS_DIRSYNC(dir))
- if (inode->i_nlink == 0) {
- ext4_warning_inode(inode, "Deleting file '%.*s' with no links",
- dentry->d_name.len, dentry->d_name.name);
- set_nlink(inode, 1);
- }
retval = ext4_delete_entry(handle, dir, de, bh);
if (retval)
goto end_unlink;
dir->i_ctime = dir->i_mtime = current_time(dir);
ext4_mark_inode_dirty(handle, dir);
- drop_nlink(inode);
+ if (inode->i_nlink == 0)
+ ext4_warning_inode(inode, "Deleting file '%.*s' with no links",
+ dentry->d_name.len, dentry->d_name.name);
+ else
+ drop_nlink(inode);
if (!inode->i_nlink)
ext4_orphan_add(handle, inode);
inode->i_ctime = current_time(inode);