[PATCH v5 3/3] xfs: reject removal of realtime flag when datadev doesn't support DAX

In a situation where the rt_dev is DAX and data_dev is not DAX, if the user requests to remove the realtime flag via ioctl we can no longer support DAX for that file. Dynamic changing of S_DAX on the inode is not supported due to various complications in the existing implementation. Therefore until we address the dynamic S_DAX change issues, we must disallow realtime flag being removed. Signed-off-by: Dave Jiang <dave.jiang(a)intel.com&gt; --- fs/xfs/xfs_ioctl.c | 14 ++++++++++++++ 1 file changed, 14 insertions(+) diff --git a/fs/xfs/xfs_ioctl.c b/fs/xfs/xfs_ioctl.c index 2c70a0a4f59f..59ec742de692 100644 --- a/fs/xfs/xfs_ioctl.c +++ b/fs/xfs/xfs_ioctl.c @@ -1030,6 +1030,20 @@ xfs_ioctl_setattr_xflags( { struct xfs_mount *mp = ip->i_mount; uint64_t di_flags2; + struct inode *inode = VFS_I(ip); + struct super_block *sb = inode->i_sb; + + /* + * In the case that the inode is realtime, and we are trying to remove + * the realtime flag, and the rtdev supports DAX but the datadev does + * not support DAX, we can't allow the realtime flag to be removed + * since we do not support dynamic S_DAX flag removal yet. + */ + if ((XFS_IS_REALTIME_INODE(ip)) && + !(fa->fsx_xflags & FS_XFLAG_REALTIME) && + bdev_dax_supported(mp->m_rtdev_targp->bt_bdev, sb->s_blocksize) && + !bdev_dax_supported(mp->m_ddev_targp->bt_bdev, sb->s_blocksize)) + return -ENOTSUPP; /* Can't change realtime flag if any extents are allocated. */ if ((ip->i_d.di_nextents || ip->i_delayed_blks) &&