6.17-stable review patch. If anyone has any objections, please let me know.
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From: Darrick J. Wong djwong@kernel.org
commit f477af0cfa0487eddec66ffe10fd9df628ba6f52 upstream.
On a filesystem with parent pointers, xchk_nlinks_collect_dir walks both the directory entries (data fork) and the parent pointers (attr fork) to determine the correct link count. Unfortunately I forgot to update the lock mode logic to handle the case of a directory whose attr fork is in btree format and has not yet been loaded *and* whose data fork doesn't need loading.
This leads to a bunch of assertions from xfs/286 in xfs_iread_extents because we only took ILOCK_SHARED, not ILOCK_EXCL. You'd need the rare happenstance of a directory with a large number of non-pptr extended attributes set and enough memory pressure to cause the directory to be evicted and partially reloaded from disk.
I /think/ this only started in 6.18-rc1 because I've started seeing OOM errors with the maple tree slab using 70% of memory, and this didn't happen in 6.17. Yay dynamic systems!
Cc: stable@vger.kernel.org # v6.10 Fixes: 77ede5f44b0d86 ("xfs: walk directory parent pointers to determine backref count") Signed-off-by: Darrick J. Wong djwong@kernel.org Reviewed-by: Christoph Hellwig hch@lst.de Signed-off-by: Carlos Maiolino cem@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- fs/xfs/scrub/nlinks.c | 34 +++++++++++++++++++++++++++++++--- 1 file changed, 31 insertions(+), 3 deletions(-)
--- a/fs/xfs/scrub/nlinks.c +++ b/fs/xfs/scrub/nlinks.c @@ -376,6 +376,36 @@ out_incomplete: return error; }
+static uint +xchk_nlinks_ilock_dir( + struct xfs_inode *ip) +{ + uint lock_mode = XFS_ILOCK_SHARED; + + /* + * We're going to scan the directory entries, so we must be ready to + * pull the data fork mappings into memory if they aren't already. + */ + if (xfs_need_iread_extents(&ip->i_df)) + lock_mode = XFS_ILOCK_EXCL; + + /* + * We're going to scan the parent pointers, so we must be ready to + * pull the attr fork mappings into memory if they aren't already. + */ + if (xfs_has_parent(ip->i_mount) && xfs_inode_has_attr_fork(ip) && + xfs_need_iread_extents(&ip->i_af)) + lock_mode = XFS_ILOCK_EXCL; + + /* + * Take the IOLOCK so that other threads cannot start a directory + * update while we're scanning. + */ + lock_mode |= XFS_IOLOCK_SHARED; + xfs_ilock(ip, lock_mode); + return lock_mode; +} + /* Walk a directory to bump the observed link counts of the children. */ STATIC int xchk_nlinks_collect_dir( @@ -394,8 +424,7 @@ xchk_nlinks_collect_dir( return 0;
/* Prevent anyone from changing this directory while we walk it. */ - xfs_ilock(dp, XFS_IOLOCK_SHARED); - lock_mode = xfs_ilock_data_map_shared(dp); + lock_mode = xchk_nlinks_ilock_dir(dp);
/* * The dotdot entry of an unlinked directory still points to the last @@ -452,7 +481,6 @@ out_abort: xchk_iscan_abort(&xnc->collect_iscan); out_unlock: xfs_iunlock(dp, lock_mode); - xfs_iunlock(dp, XFS_IOLOCK_SHARED); return error; }