diff mbox series

[6.6,13/17] xfs: conditionally allow FS_XFLAG_REALTIME changes if S_DAX is set

Message ID 20241218191725.63098-14-catherine.hoang@oracle.com (mailing list archive)
State New
Headers show
Series xfs backports for 6.6.y (from 6.11) | expand

Commit Message

Catherine Hoang Dec. 18, 2024, 7:17 p.m. UTC 
From: "Darrick J. Wong" <djwong@kernel.org>

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@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Chandan Babu R <chandanbabu@kernel.org>
Signed-off-by: Catherine Hoang <catherine.hoang@oracle.com>
Acked-by: Darrick J. Wong <djwong@kernel.org>
---
 fs/xfs/xfs_ioctl.c | 11 +++++++++++
 1 file changed, 11 insertions(+)
diff mbox series

Patch

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) {