This is a note to let you know that I've just added the patch titled
xfs: conditionally allow FS_XFLAG_REALTIME changes if S_DAX is set
to the 6.6-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:
xfs-conditionally-allow-fs_xflag_realtime-changes-if.patch
and it can be found in the queue-6.6 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 6e35ee75134d50774464613eb3d40046774fda13
Author: Darrick J. Wong <djwong@xxxxxxxxxx>
Date: Wed Dec 18 11:17:21 2024 -0800
xfs: conditionally allow FS_XFLAG_REALTIME changes if S_DAX is set
commit 8d16762047c627073955b7ed171a36addaf7b1ff upstream.
If a file has the S_DAX flag (aka fsdax access mode) set, we cannot
allow users to change the realtime flag unless the datadev and rtdev
both support fsdax access modes. Even if there are no extents allocated
to the file, the setattr thread could be racing with another thread
that has already started down the write code paths.
Fixes: ba23cba9b3bdc ("fs: allow per-device dax status checking for filesystems")
Signed-off-by: Darrick J. Wong <djwong@xxxxxxxxxx>
Reviewed-by: Christoph Hellwig <hch@xxxxxx>
Signed-off-by: Chandan Babu R <chandanbabu@xxxxxxxxxx>
Signed-off-by: Catherine Hoang <catherine.hoang@xxxxxxxxxx>
Acked-by: Darrick J. Wong <djwong@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/fs/xfs/xfs_ioctl.c b/fs/xfs/xfs_ioctl.c
index df4bf0d56aad..32e718043e0e 100644
--- a/fs/xfs/xfs_ioctl.c
+++ b/fs/xfs/xfs_ioctl.c
@@ -1128,6 +1128,17 @@ xfs_ioctl_setattr_xflags(
/* Can't change realtime flag if any extents are allocated. */
if (ip->i_df.if_nextents || ip->i_delayed_blks)
return -EINVAL;
+
+ /*
+ * If S_DAX is enabled on this file, we can only switch the
+ * device if both support fsdax. We can't update S_DAX because
+ * there might be other threads walking down the access paths.
+ */
+ if (IS_DAX(VFS_I(ip)) &&
+ (mp->m_ddev_targp->bt_daxdev == NULL ||
+ (mp->m_rtdev_targp &&
+ mp->m_rtdev_targp->bt_daxdev == NULL)))
+ return -EINVAL;
}
if (rtflag) {
