From: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
Data block sharing (a.k.a. reflink) has been stable for a while, so turn
it on by default.
Signed-off-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
[sandeen: update comments & man page]
Signed-off-by: Eric Sandeen <sandeen@xxxxxxxxxx>
---
diff --git a/man/man8/mkfs.xfs.8 b/man/man8/mkfs.xfs.8
index 4b8c78c..78b1501 100644
--- a/man/man8/mkfs.xfs.8
+++ b/man/man8/mkfs.xfs.8
@@ -231,7 +231,7 @@ available for the data forks of regular files.
.IP
By default,
.B mkfs.xfs
-will not create reference count btrees and therefore will not enable the
+will create reference count btrees and therefore will enable the
reflink feature. This feature is only available for filesystems created with
the (default)
.B \-m crc=1
@@ -239,6 +239,13 @@ option set. When the option
.B \-m crc=0
is used, the reference count btree feature is not supported and reflink is
disabled.
+.IP
+Note: the filesystem DAX mount option (
+.B \-o dax
+) is incompatible with
+reflink-enabled XFS filesystems. To use filesystem DAX with XFS, specify the
+.B \-m reflink=0
+option to mkfs.xfs to disable the reflink feature.
.RE
.TP
.BI \-d " data_section_options"
diff --git a/mkfs/xfs_mkfs.c b/mkfs/xfs_mkfs.c
index 0910664..ddb25ec 100644
--- a/mkfs/xfs_mkfs.c
+++ b/mkfs/xfs_mkfs.c
@@ -1973,15 +1973,15 @@ _("Directory ftype field always enabled on CRC enabled filesystems\n"));
usage();
}
- } else {
+ } else { /* !crcs_enabled */
/*
- * The kernel doesn't currently support crc=0,finobt=1
- * filesystems. If crcs are not enabled and the user has not
- * explicitly turned finobt on, then silently turn it off to
- * avoid an unnecessary warning.
+ * The kernel doesn't support crc=0,finobt=1 filesystems.
+ * If crcs are not enabled and the user has not explicitly
+ * turned finobt on, then silently turn it off to avoid an
+ * unnecessary warning.
* If the user explicitly tried to use crc=0,finobt=1,
* then issue an error.
- * The same is also for sparse inodes.
+ * The same is also true for sparse inodes and reflink.
*/
if (cli->sb_feat.finobt && cli_opt_set(&mopts, M_FINOBT)) {
fprintf(stderr,
@@ -2004,7 +2004,7 @@ _("rmapbt not supported without CRC support\n"));
}
cli->sb_feat.rmapbt = false;
- if (cli->sb_feat.reflink) {
+ if (cli->sb_feat.reflink && cli_opt_set(&mopts, M_REFLINK)) {
fprintf(stderr,
_("reflink not supported without CRC support\n"));
usage();
@@ -3876,7 +3876,7 @@ main(
.finobt = true,
.spinodes = true,
.rmapbt = false,
- .reflink = false,
+ .reflink = true,
.parent_pointers = false,
.nodalign = false,
.nortalign = false,
