[RFC PATCH V2 03/12] fs/xfs: Separate functionality of xfs_inode_supports_dax()

[ira . weiny]

From: Ira Weiny <ira.weiny@xxxxxxxxx>

xfs_inode_supports_dax() should reflect if the inode can support DAX not
that it is enabled for DAX.  Leave that to other helper functions.

Change the caller of xfs_inode_supports_dax() to call
xfs_inode_use_dax() which reflects new logic to override the effective
DAX flag with either the mount option or the physical DAX flag.

To make the logic clear create 2 helper functions for the mount and
physical flag.

Signed-off-by: Ira Weiny <ira.weiny@xxxxxxxxx>
---
 fs/xfs/xfs_iops.c | 32 ++++++++++++++++++++++++++------
 1 file changed, 26 insertions(+), 6 deletions(-)

diff --git a/fs/xfs/xfs_iops.c b/fs/xfs/xfs_iops.c
index 8afe69ca188b..0a0ea90259e9 100644
--- a/fs/xfs/xfs_iops.c
+++ b/fs/xfs/xfs_iops.c
@@ -1234,6 +1234,15 @@ static const struct inode_operations xfs_inline_symlink_inode_operations = {
 	.update_time		= xfs_vn_update_time,
 };
 
+static bool
+xfs_inode_mount_is_dax(
+	struct xfs_inode *ip)
+{
+	struct xfs_mount	*mp = ip->i_mount;
+
+	return (mp->m_flags & XFS_MOUNT_DAX) == XFS_MOUNT_DAX;
+}
+
 /* Figure out if this file actually supports DAX. */
 static bool
 xfs_inode_supports_dax(
@@ -1245,11 +1254,6 @@ xfs_inode_supports_dax(
 	if (!S_ISREG(VFS_I(ip)->i_mode) || xfs_is_reflink_inode(ip))
 		return false;
 
-	/* DAX mount option or DAX iflag must be set. */
-	if (!(mp->m_flags & XFS_MOUNT_DAX) &&
-	    !(ip->i_d.di_flags2 & XFS_DIFLAG2_DAX))
-		return false;
-
 	/* Block size must match page size */
 	if (mp->m_sb.sb_blocksize != PAGE_SIZE)
 		return false;
@@ -1258,6 +1262,22 @@ xfs_inode_supports_dax(
 	return xfs_inode_buftarg(ip)->bt_daxdev != NULL;
 }
 
+static bool
+xfs_inode_is_dax(
+	struct xfs_inode *ip)
+{
+	return (ip->i_d.di_flags2 & XFS_DIFLAG2_DAX) == XFS_DIFLAG2_DAX;
+}
+
+static bool
+xfs_inode_use_dax(
+	struct xfs_inode *ip)
+{
+	return xfs_inode_supports_dax(ip) &&
+		(xfs_inode_mount_is_dax(ip) ||
+		 xfs_inode_is_dax(ip));
+}
+
 STATIC void
 xfs_diflags_to_iflags(
 	struct inode		*inode,
@@ -1276,7 +1296,7 @@ xfs_diflags_to_iflags(
 		inode->i_flags |= S_SYNC;
 	if (flags & XFS_DIFLAG_NOATIME)
 		inode->i_flags |= S_NOATIME;
-	if (xfs_inode_supports_dax(ip))
+	if (xfs_inode_use_dax(ip))
 		inode->i_flags |= S_DAX;
 }
 
-- 
2.21.0