Commit 8d167620 authored by Darrick J. Wong's avatar Darrick J. Wong Committed by Chandan Babu R
Browse files

xfs: conditionally allow FS_XFLAG_REALTIME changes if S_DAX is set 



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: ba23cba9 ("fs: allow per-device dax status checking for filesystems")
Signed-off-by: default avatarDarrick J. Wong <djwong@kernel.org>
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Signed-off-by: default avatarChandan Babu R <chandanbabu@kernel.org>
parent 04d6dbb5

fs/xfs/xfs_ioctl.c

+11 −0
Original line number Diff line number Diff line
@@ -483,6 +483,17 @@ 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) {