[PATCH 03/22] libxfs: apply rt extent alignment constraints to CoW extsize hint

Darrick J. Wong
2025-02-06T22:57:33Z

The copy-on-write extent size hint is subject to the same alignment
constraints as the regular extent size hint. Since we're in the process
of adding reflink (and therefore CoW) to the realtime device, we must
apply the same scattered rextsize alignment validation strategies to
both hints to deal with the possibility of rextsize changing.

Therefore, fix the inode validator to perform rextsize alignment checks
on regular realtime files, and to remove misaligned directory hints.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
---
libxfs/logitem.c | 14 ++++++++++++++
1 file changed, 14 insertions(+)

diff --git a/libxfs/logitem.c b/libxfs/logitem.c
index 7757259dfc5e42..062d6311b942ae 100644
--- a/libxfs/logitem.c
+++ b/libxfs/logitem.c
@@ -233,6 +233,20 @@ xfs_inode_item_precommit(
if (flags & XFS_ILOG_IVERSION)
flags = ((flags & ~XFS_ILOG_IVERSION) | XFS_ILOG_CORE);

+ /*
+ * Inode verifiers do not check that the CoW extent size hint is an
+ * integer multiple of the rt extent size on a directory with both
+ * rtinherit and cowextsize flags set. If we're logging a directory
+ * that is misconfigured in this way, clear the hint.
+ */
+ if ((ip->i_diflags & XFS_DIFLAG_RTINHERIT) &&
+ (ip->i_diflags2 & XFS_DIFLAG2_COWEXTSIZE) &&
+ xfs_extlen_to_rtxmod(ip->i_mount, ip->i_cowextsize) > 0) {
+ ip->i_diflags2 &= ~XFS_DIFLAG2_COWEXTSIZE;
+ ip->i_cowextsize = 0;
+ flags |= XFS_ILOG_CORE;
+ }
+
if (!iip->ili_item.li_buf) {
struct xfs_buf *bp;
int error;