This is a note to let you know that I've just added the patch titled ext4: work around deleting a file with i_nlink == 0 safely to the 4.4-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: ext4-work-around-deleting-a-file-with-i_nlink-0-safe.patch and it can be found in the queue-4.4 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit f32ff790b2fa9807a541020c841beced452ab4b1 Author: Theodore Ts'o <tytso@xxxxxxx> Date: Mon Nov 11 22:18:13 2019 -0500 ext4: work around deleting a file with i_nlink == 0 safely [ Upstream commit c7df4a1ecb8579838ec8c56b2bb6a6716e974f37 ] 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@xxxxxxx Signed-off-by: Theodore Ts'o <tytso@xxxxxxx> Cc: stable@xxxxxxxxxx Reviewed-by: Andreas Dilger <adilger@xxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c index aa08e129149d..712bf332e394 100644 --- a/fs/ext4/namei.c +++ b/fs/ext4/namei.c @@ -3040,18 +3040,17 @@ static int ext4_unlink(struct inode *dir, struct dentry *dentry) 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 = ext4_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 = ext4_current_time(inode);