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Message-ID: <20200416041553.GF2309605@iweiny-DESK2.sc.intel.com>
Date: Wed, 15 Apr 2020 21:15:54 -0700
From: Ira Weiny <ira.weiny@...el.com>
To: "Darrick J. Wong" <darrick.wong@...cle.com>
Cc: linux-kernel@...r.kernel.org, Jan Kara <jack@...e.cz>,
Dan Williams <dan.j.williams@...el.com>,
Dave Chinner <david@...morbit.com>,
Christoph Hellwig <hch@....de>,
"Theodore Y. Ts'o" <tytso@....edu>, Jeff Moyer <jmoyer@...hat.com>,
linux-ext4@...r.kernel.org, linux-xfs@...r.kernel.org,
linux-fsdevel@...r.kernel.org
Subject: Re: [PATCH V8 05/11] fs/xfs: Make DAX mount option a tri-state
On Wed, Apr 15, 2020 at 08:16:13AM -0700, Darrick J. Wong wrote:
> On Tue, Apr 14, 2020 at 11:45:17PM -0700, ira.weiny@...el.com wrote:
> > From: Ira Weiny <ira.weiny@...el.com>
> >
> > 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@iweiny-DESK2.sc.intel.com/
> >
> > Signed-off-by: Ira Weiny <ira.weiny@...el.com>
> >
> > ---
> > Changes from v7:
> > Change to XFS_MOUNT_DAX_NEVER
> >
> > 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 54bd74088936..2e88c30642e3 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_ALWAYS (1ULL << 62) /* TEST ONLY! */
> > +#define XFS_MOUNT_DAX_ALWAYS (1ULL << 62)
> > +#define XFS_MOUNT_DAX_NEVER (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 3863f41757d2..142e5d03566f 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 {
>
> enum xfs_dax_mode { for the reasons given below?
>
> > + 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)
>
> xfs style, please:
>
> static void
> xfs_mount_set_dax_mode(
> struct xfs_mount *mp,
> u32 val)
NP changed.
>
> or if you give a name to the enum above, you can enforce some type
> safety too:
>
> enum xfs_dax_mode val)
The problem is that the option parsing returns result.uint_32 type. Generally
I agree with using more specific types but here I'm not sure it matters.
>
> > +{
> > + if (val == XFS_DAX_INODE) {
>
> and this probably could have been a "switch (val) {", in which case if
> the enum ever gets expanded then gcc will whine about missing switch
> cases.
Sure... that does require the enum to be defined and used in the signature...
Ok I'll use the enum! :-D
done.
Thanks,
Ira
>
> The rest of the patch looks good.
>
> --D
>
> > + mp->m_flags &= ~(XFS_MOUNT_DAX_ALWAYS | XFS_MOUNT_DAX_NEVER);
> > + } else if (val == XFS_DAX_ALWAYS) {
> > + mp->m_flags |= XFS_MOUNT_DAX_ALWAYS;
> > + mp->m_flags &= ~XFS_MOUNT_DAX_NEVER;
> > + } else if (val == XFS_DAX_NEVER) {
> > + mp->m_flags |= XFS_MOUNT_DAX_NEVER;
> > + mp->m_flags &= ~XFS_MOUNT_DAX_ALWAYS;
> > + }
> > +}
> > +
> > +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_ALWAYS, ",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_ALWAYS)
> > + seq_puts(m, ",dax=always");
> > + else if (mp->m_flags & XFS_MOUNT_DAX_NEVER)
> > + 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_ALWAYS;
> > + 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_ALWAYS;
> > + xfs_mount_set_dax_mode(mp, XFS_DAX_NEVER);
> > }
> > if (xfs_sb_version_hasreflink(&mp->m_sb)) {
> > xfs_alert(mp,
> > --
> > 2.25.1
> >
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