From: Theodore Ts'o tytso@mit.edu
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: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- fs/ext4/namei.c | 11 +++++------ 1 file changed, 5 insertions(+), 6 deletions(-)
--- a/fs/ext4/namei.c +++ b/fs/ext4/namei.c @@ -3056,18 +3056,17 @@ static int ext4_unlink(struct inode *dir if (IS_DIRSYNC(dir)) ext4_handle_sync(handle);
- 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_update_dx_flag(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);