linux-kernel - Re: [PATCH 1/2] i915: convert to new mount API

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Date:   Fri, 2 Aug 2019 22:10:37 +0900
From:   Sergey Senozhatsky <sergey.senozhatsky@...il.com>
To:     Chris Wilson <chris@...is-wilson.co.uk>
Cc:     Jani Nikula <jani.nikula@...ux.intel.com>,
        Joonas Lahtinen <joonas.lahtinen@...ux.intel.com>,
        Rodrigo Vivi <rodrigo.vivi@...el.com>,
        Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        intel-gfx@...ts.freedesktop.org, dri-devel@...ts.freedesktop.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] i915: convert to new mount API

On (08/02/19 13:54), Chris Wilson wrote:
[..]
> >  int i915_gemfs_init(struct drm_i915_private *i915)
> >  {
> > +       struct fs_context *fc = NULL;
> >         struct file_system_type *type;
> >         struct vfsmount *gemfs;
> > +       bool ok = true;
> 
> Start with ok = false, we only need to set to true if we succeed in
> reconfiguring.

OK, makes sense.

> >         type = get_fs_type("tmpfs");
> >         if (!type)
> > @@ -36,18 +39,29 @@ int i915_gemfs_init(struct drm_i915_private *i915)
> >                 struct super_block *sb = gemfs->mnt_sb;
> >                 /* FIXME: Disabled until we get W/A for read BW issue. */
> >                 char options[] = "huge=never";
> > -               int flags = 0;
> > -               int err;
> 
> Hmm, we could avoid this if we used vfs_kernel_mount() directly rather
> than the kern_mount wrapper, as then we pass options through to
> parse_monotithic_mount_data(). Or am I barking up the wrong tree?

Hmm.
Wouldn't this error on !TRANSPARENT_HUGE_PAGECACHE systems?
"huge=never" should be an invalid option when system does
not know about THP.

[..]
> > +               if (!fc->ops->parse_monolithic ||
> > +                               fc->ops->parse_monolithic(fc, options)) {
> 
> checkpatch.pl will complain that this should line up with the '('

It doesn't.

-------------------------------------------------
outgoing/0001-i915-convert-to-new-mount-API.patch
-------------------------------------------------
total: 0 errors, 0 warnings, 53 lines checked

outgoing/0001-i915-convert-to-new-mount-API.patch has no obvious style problems and is ready for submission.

-------------------------------------------------------
outgoing/0002-i915-do-not-leak-module-ref-counter.patch
-------------------------------------------------------
total: 0 errors, 0 warnings, 11 lines checked

outgoing/0002-i915-do-not-leak-module-ref-counter.patch has no obvious style problems and is ready for submission.

[..]
> > +       if (!ok)
> > +               pr_err("i915 gemfs reconfiguration failed\n");
> 
> Let's make it a bit more user friendly,
> 
> dev_err(i915->drm.dev,
> 	"Unable to reconfigure internal shmemfs for preferred"
> 	" allocation strategy; continuing, but performance may suffer.\n");

I guess now checkpatch will complain :)

> Assuming that we can't just use vfs_kern_mount() instead, with the nits
> Reviewed-by: Chris Wilson <chris@...is-wilson.co.uk>

Thanks.

I'll sit on it for several days, just to see if more feedback will come.

	-ss