[PATCH V7 4/9] fs/xfs: Make DAX mount option a tri-state

From: ira . weiny
Date: Mon Apr 13 2020 - 01:41:31 EST


From: Ira Weiny <ira.weiny@xxxxxxxxx>

As agreed upon[1]. We make the dax mount option a tri-state. '-o dax'
continues to operate the same. We add 'always', 'never', and 'inode'
(default).

[1] https://lore.kernel.org/lkml/20200405061945.GA94792@xxxxxxxxxxxxxxxxxxxxxxxxx/

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

---
Changes from v6:
Use 2 flag bits rather than a field.
change iflag to inode

Changes from v5:
New Patch
---
fs/xfs/xfs_mount.h | 3 ++-
fs/xfs/xfs_super.c | 44 ++++++++++++++++++++++++++++++++++++++++----
2 files changed, 42 insertions(+), 5 deletions(-)

diff --git a/fs/xfs/xfs_mount.h b/fs/xfs/xfs_mount.h
index 88ab09ed29e7..d581b990e59a 100644
--- a/fs/xfs/xfs_mount.h
+++ b/fs/xfs/xfs_mount.h
@@ -233,7 +233,8 @@ typedef struct xfs_mount {
allocator */
#define XFS_MOUNT_NOATTR2 (1ULL << 25) /* disable use of attr2 format */

-#define XFS_MOUNT_DAX (1ULL << 62) /* TEST ONLY! */
+#define XFS_MOUNT_DAX (1ULL << 62)
+#define XFS_MOUNT_NODAX (1ULL << 63)

/*
* Max and min values for mount-option defined I/O
diff --git a/fs/xfs/xfs_super.c b/fs/xfs/xfs_super.c
index 2094386af8ac..d7bd8f5e00c9 100644
--- a/fs/xfs/xfs_super.c
+++ b/fs/xfs/xfs_super.c
@@ -47,6 +47,32 @@ static struct kset *xfs_kset; /* top-level xfs sysfs dir */
static struct xfs_kobj xfs_dbg_kobj; /* global debug sysfs attrs */
#endif

+enum {
+ XFS_DAX_INODE = 0,
+ XFS_DAX_ALWAYS = 1,
+ XFS_DAX_NEVER = 2,
+};
+
+static void xfs_mount_set_dax_mode(struct xfs_mount *mp, u32 val)
+{
+ if (val == XFS_DAX_INODE) {
+ mp->m_flags &= ~(XFS_MOUNT_DAX | XFS_MOUNT_NODAX);
+ } else if (val == XFS_DAX_ALWAYS) {
+ mp->m_flags &= ~XFS_MOUNT_NODAX;
+ mp->m_flags |= XFS_MOUNT_DAX;
+ } else if (val == XFS_DAX_NEVER) {
+ mp->m_flags &= ~XFS_MOUNT_DAX;
+ mp->m_flags |= XFS_MOUNT_NODAX;
+ }
+}
+
+static const struct constant_table dax_param_enums[] = {
+ {"inode", XFS_DAX_INODE },
+ {"always", XFS_DAX_ALWAYS },
+ {"never", XFS_DAX_NEVER },
+ {}
+};
+
/*
* Table driven mount option parser.
*/
@@ -59,7 +85,7 @@ enum {
Opt_filestreams, Opt_quota, Opt_noquota, Opt_usrquota, Opt_grpquota,
Opt_prjquota, Opt_uquota, Opt_gquota, Opt_pquota,
Opt_uqnoenforce, Opt_gqnoenforce, Opt_pqnoenforce, Opt_qnoenforce,
- Opt_discard, Opt_nodiscard, Opt_dax,
+ Opt_discard, Opt_nodiscard, Opt_dax, Opt_dax_enum,
};

static const struct fs_parameter_spec xfs_fs_parameters[] = {
@@ -103,6 +129,7 @@ static const struct fs_parameter_spec xfs_fs_parameters[] = {
fsparam_flag("discard", Opt_discard),
fsparam_flag("nodiscard", Opt_nodiscard),
fsparam_flag("dax", Opt_dax),
+ fsparam_enum("dax", Opt_dax_enum, dax_param_enums),
{}
};

@@ -129,7 +156,6 @@ xfs_fs_show_options(
{ XFS_MOUNT_GRPID, ",grpid" },
{ XFS_MOUNT_DISCARD, ",discard" },
{ XFS_MOUNT_LARGEIO, ",largeio" },
- { XFS_MOUNT_DAX, ",dax" },
{ 0, NULL }
};
struct xfs_mount *mp = XFS_M(root->d_sb);
@@ -185,6 +211,13 @@ xfs_fs_show_options(
if (!(mp->m_qflags & XFS_ALL_QUOTA_ACCT))
seq_puts(m, ",noquota");

+ if (mp->m_flags & XFS_MOUNT_DAX)
+ seq_puts(m, ",dax=always");
+ else if (mp->m_flags & XFS_MOUNT_NODAX)
+ seq_puts(m, ",dax=never");
+ else
+ seq_puts(m, ",dax=inode");
+
return 0;
}

@@ -1244,7 +1277,10 @@ xfs_fc_parse_param(
return 0;
#ifdef CONFIG_FS_DAX
case Opt_dax:
- mp->m_flags |= XFS_MOUNT_DAX;
+ xfs_mount_set_dax_mode(mp, XFS_DAX_ALWAYS);
+ return 0;
+ case Opt_dax_enum:
+ xfs_mount_set_dax_mode(mp, result.uint_32);
return 0;
#endif
default:
@@ -1451,7 +1487,7 @@ xfs_fc_fill_super(
if (!rtdev_is_dax && !datadev_is_dax) {
xfs_alert(mp,
"DAX unsupported by block device. Turning off DAX.");
- mp->m_flags &= ~XFS_MOUNT_DAX;
+ xfs_mount_set_dax_mode(mp, XFS_DAX_NEVER);
}
if (xfs_sb_version_hasreflink(&mp->m_sb)) {
xfs_alert(mp,
--
2.25.1