[PATCH V4 05/13] fs/xfs: Isolate the physical DAX flag from enabled

[ira . weiny]

From: Ira Weiny <ira.weiny@xxxxxxxxx>

xfs_ioctl_setattr_dax_invalidate() currently checks if the DAX flag is
changing as a quick check.

But the implementation mixes the physical (XFS_DIFLAG2_DAX) and
the enabled (S_DAX) DAX flags.

Remove the use of the enabled flag when determining if a change of the
physical flag is required.

Furthermore, we want the physical flag, XFS_DIFLAG2_DAX, to be changed
regardless of if the underlying storage can support DAX or not.

The enabled flag, IS_DAX(), will be set later IFF the inode supports
dax in a follow on patch.

Signed-off-by: Ira Weiny <ira.weiny@xxxxxxxxx>

---
Changes from V3:
	Remove the underlying storage support check
	Rework commit message
	Reorder patch
---
 fs/xfs/xfs_ioctl.c | 20 ++++----------------
 1 file changed, 4 insertions(+), 16 deletions(-)

diff --git a/fs/xfs/xfs_ioctl.c b/fs/xfs/xfs_ioctl.c
index d42de92cb283..25e12ce85075 100644
--- a/fs/xfs/xfs_ioctl.c
+++ b/fs/xfs/xfs_ioctl.c
@@ -1190,28 +1190,16 @@ xfs_ioctl_setattr_dax_invalidate(
 	int			*join_flags)
 {
 	struct inode		*inode = VFS_I(ip);
-	struct super_block	*sb = inode->i_sb;
 	int			error;
 
 	*join_flags = 0;
 
-	/*
-	 * It is only valid to set the DAX flag on regular files and
-	 * directories on filesystems where the block size is equal to the page
-	 * size. On directories it serves as an inherited hint so we don't
-	 * have to check the device for dax support or flush pagecache.
-	 */
-	if (fa->fsx_xflags & FS_XFLAG_DAX) {
-		struct xfs_buftarg	*target = xfs_inode_buftarg(ip);
-
-		if (!bdev_dax_supported(target->bt_bdev, sb->s_blocksize))
-			return -EINVAL;
-	}
-
 	/* If the DAX state is not changing, we have nothing to do here. */
-	if ((fa->fsx_xflags & FS_XFLAG_DAX) && IS_DAX(inode))
+	if ((fa->fsx_xflags & FS_XFLAG_DAX) &&
+	    (ip->i_d.di_flags2 & XFS_DIFLAG2_DAX))
 		return 0;
-	if (!(fa->fsx_xflags & FS_XFLAG_DAX) && !IS_DAX(inode))
+	if (!(fa->fsx_xflags & FS_XFLAG_DAX) &&
+	    !(ip->i_d.di_flags2 & XFS_DIFLAG2_DAX))
 		return 0;
 
 	if (S_ISDIR(inode->i_mode))
-- 
2.21.0