[PATCH v2 4/4] mkfs: allow setting dax flag on root directory

["Darrick J. Wong" <darrick.wong@oracle.com>]

From: Darrick J. Wong <darrick.wong@oracle.com>

Teach mkfs to set the DAX flag on the root directory so that all new
files can be created in dax mode.  This is a complement to removing the
mount option.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Carlos Maiolino <cmaiolino@redhat.com>
---
v2: minor tweak to manpage text
---
 man/man8/mkfs.xfs.8 |   10 ++++++++++
 mkfs/xfs_mkfs.c     |   14 ++++++++++++++
 2 files changed, 24 insertions(+)

diff --git a/man/man8/mkfs.xfs.8 b/man/man8/mkfs.xfs.8
index 7d3f3552ff12..0a7858748457 100644
--- a/man/man8/mkfs.xfs.8
+++ b/man/man8/mkfs.xfs.8
@@ -398,6 +398,16 @@ will have this extent size hint applied.
 The value must be provided in units of filesystem blocks.
 Directories will pass on this hint to newly created regular files and
 directories.
+.TP
+.BI daxinherit= value
+If set, all inodes created by
+.B mkfs.xfs
+will be created with the DAX flag set.
+Directories will pass on this flag to newly created regular files and
+directories.
+By default,
+.B mkfs.xfs
+will not enable DAX mode.
 .RE
 .TP
 .B \-f
diff --git a/mkfs/xfs_mkfs.c b/mkfs/xfs_mkfs.c
index 2e6cd280e388..a687f385a9c1 100644
--- a/mkfs/xfs_mkfs.c
+++ b/mkfs/xfs_mkfs.c
@@ -60,6 +60,7 @@ enum {
 	D_PROJINHERIT,
 	D_EXTSZINHERIT,
 	D_COWEXTSIZE,
+	D_DAXINHERIT,
 	D_MAX_OPTS,
 };
 
@@ -254,6 +255,7 @@ static struct opt_params dopts = {
 		[D_PROJINHERIT] = "projinherit",
 		[D_EXTSZINHERIT] = "extszinherit",
 		[D_COWEXTSIZE] = "cowextsize",
+		[D_DAXINHERIT] = "daxinherit",
 	},
 	.subopt_params = {
 		{ .index = D_AGCOUNT,
@@ -369,6 +371,12 @@ static struct opt_params dopts = {
 		  .maxval = UINT_MAX,
 		  .defaultval = SUBOPT_NEEDS_VAL,
 		},
+		{ .index = D_DAXINHERIT,
+		  .conflicts = { { NULL, LAST_CONFLICT } },
+		  .minval = 0,
+		  .maxval = 1,
+		  .defaultval = 1,
+		},
 	},
 };
 
@@ -1434,6 +1442,12 @@ data_opts_parser(
 		cli->fsx.fsx_cowextsize = getnum(value, opts, subopt);
 		cli->fsx.fsx_xflags |= FS_XFLAG_COWEXTSIZE;
 		break;
+	case D_DAXINHERIT:
+		if (getnum(value, opts, subopt))
+			cli->fsx.fsx_xflags |= FS_XFLAG_DAX;
+		else
+			cli->fsx.fsx_xflags &= ~FS_XFLAG_DAX;
+		break;
 	default:
 		return -EINVAL;
 	}