From 5838d0356bb3c320867c393f12b169c01a870bda Mon Sep 17 00:00:00 2001 From: "Darrick J. Wong" Date: Mon, 12 Jul 2021 12:58:48 -0700 Subject: xfs: reset child dir '..' entry when unlinking child While running xfs/168, I noticed a second source of post-shrink corruption errors causing shutdowns. Let's say that directory B has a low inode number and is a child of directory A, which has a high number. If B is empty but open, and unlinked from A, B's dotdot link continues to point to A. If A is then unlinked and the filesystem shrunk so that A is no longer a valid inode, a subsequent AIL push of B will trip the inode verifiers because the dotdot entry points outside of the filesystem. To avoid this problem, reset B's dotdot entry to the root directory when unlinking directories, since the root directory cannot be removed. Signed-off-by: Darrick J. Wong Reviewed-by: Gao Xiang --- fs/xfs/xfs_inode.c | 13 +++++++++++++ 1 file changed, 13 insertions(+) diff --git a/fs/xfs/xfs_inode.c b/fs/xfs/xfs_inode.c index a835ceb79ba5..990b72ae3635 100644 --- a/fs/xfs/xfs_inode.c +++ b/fs/xfs/xfs_inode.c @@ -2763,6 +2763,19 @@ xfs_remove( error = xfs_droplink(tp, ip); if (error) goto out_trans_cancel; + + /* + * Point the unlinked child directory's ".." entry to the root + * directory to eliminate back-references to inodes that may + * get freed before the child directory is closed. If the fs + * gets shrunk, this can lead to dirent inode validation errors. + */ + if (dp->i_ino != tp->t_mountp->m_sb.sb_rootino) { + error = xfs_dir_replace(tp, ip, &xfs_name_dotdot, + tp->t_mountp->m_sb.sb_rootino, 0); + if (error) + return error; + } } else { /* * When removing a non-directory we need to log the parent -- cgit v1.2.3