Merge tag 'xfs-5.16-fixes-3' of git://git.kernel.org/pub/scm/fs/xfs/xfs-linux
Pull xfs fix from Darrick Wong:
"This fixes a race between a readonly remount process and other
processes that hold a file IOLOCK on files that previously experienced
copy on write, that could result in severe filesystem corruption if
the filesystem is then remounted rw.
I think this is fairly rare (since the only reliable reproducer I have
that fits the second criteria is the experimental xfs_scrub program),
but the race is clear, so we still need to fix this.
Summary:
- Fix a data corruption vector that can result from the ro remount
process failing to clear all speculative preallocations from files
and the rw remount process not noticing the incomplete cleanup"
* tag 'xfs-5.16-fixes-3' of git://git.kernel.org/pub/scm/fs/xfs/xfs-linux:
xfs: remove all COW fork extents when remounting readonly
diff --git a/fs/xfs/xfs_super.c b/fs/xfs/xfs_super.c
index e21459f..778b57b 100644
--- a/fs/xfs/xfs_super.c
+++ b/fs/xfs/xfs_super.c
@@ -1765,7 +1765,10 @@ static int
xfs_remount_ro(
struct xfs_mount *mp)
{
- int error;
+ struct xfs_icwalk icw = {
+ .icw_flags = XFS_ICWALK_FLAG_SYNC,
+ };
+ int error;
/*
* Cancel background eofb scanning so it cannot race with the final
@@ -1773,8 +1776,13 @@ xfs_remount_ro(
*/
xfs_blockgc_stop(mp);
- /* Get rid of any leftover CoW reservations... */
- error = xfs_blockgc_free_space(mp, NULL);
+ /*
+ * Clear out all remaining COW staging extents and speculative post-EOF
+ * preallocations so that we don't leave inodes requiring inactivation
+ * cleanups during reclaim on a read-only mount. We must process every
+ * cached inode, so this requires a synchronous cache scan.
+ */
+ error = xfs_blockgc_free_space(mp, &icw);
if (error) {
xfs_force_shutdown(mp, SHUTDOWN_CORRUPT_INCORE);
return error;