From: Al Viro <viro@zeniv.linux.org.uk>
To: Jeff Moyer <jmoyer@redhat.com>
Cc: "Fabio M. De Francesco" <fmdefrancesco@gmail.com>,
Benjamin LaHaise <bcrl@kvack.org>,
linux-aio@kvack.org, linux-fsdevel@vger.kernel.org,
linux-kernel@vger.kernel.org, "Venkataramanan,
Anirudh" <anirudh.venkataramanan@intel.com>,
Ira Weiny <ira.weiny@intel.com>
Subject: Re: [PATCH v2] fs/aio: Replace kmap{,_atomic}() with kmap_local_page()
Date: Wed, 11 Jan 2023 16:02:26 +0000 [thread overview]
Message-ID: <Y77dkghufF6GVq1Y@ZenIV> (raw)
In-Reply-To: <x498ri9ma5n.fsf@segfault.boston.devel.redhat.com>
On Wed, Jan 11, 2023 at 09:13:40AM -0500, Jeff Moyer wrote:
> Hi, Al,
>
> Al Viro <viro@zeniv.linux.org.uk> writes:
>
> > On Mon, Jan 09, 2023 at 06:56:29PM +0100, Fabio M. De Francesco wrote:
> >
> >> - ring = kmap_atomic(ctx->ring_pages[0]);
> >> + ring = kmap_local_page(ctx->ring_pages[0]);
> >> ring->nr = nr_events; /* user copy */
> >> ring->id = ~0U;
> >> ring->head = ring->tail = 0;
> >> @@ -575,7 +575,7 @@ static int aio_setup_ring(struct kioctx *ctx, unsigned int nr_events)
> >> ring->compat_features = AIO_RING_COMPAT_FEATURES;
> >> ring->incompat_features = AIO_RING_INCOMPAT_FEATURES;
> >> ring->header_length = sizeof(struct aio_ring);
> >> - kunmap_atomic(ring);
> >> + kunmap_local(ring);
> >> flush_dcache_page(ctx->ring_pages[0]);
> >
> > I wonder if it would be more readable as memcpy_to_page(), actually...
>
> I'm not sure I understand what you're suggesting.
memcpy_to_page(ctx->ring_pages[0], 0, &(struct aio_ring){
.nr = nr_events, .id = ~0U, .magic = AIO_RING_MAGIC,
.compat_features = AIO_RING_COMPAT_FEATURES,
.in_compat_features = AIO_RING_INCOMPAT_FEATURES,
.header_length = sizeof(struct aio_ring)},
sizeof(struct aio_ring));
instead of the lines from kmap_atomic to flush_dcache_page...
>
> >>
> >> return 0;
> >> @@ -678,9 +678,9 @@ static int ioctx_add_table(struct kioctx *ctx, struct mm_struct *mm)
> >> * we are protected from page migration
> >> * changes ring_pages by ->ring_lock.
> >> */
> >> - ring = kmap_atomic(ctx->ring_pages[0]);
> >> + ring = kmap_local_page(ctx->ring_pages[0]);
> >> ring->id = ctx->id;
> >> - kunmap_atomic(ring);
> >> + kunmap_local(ring);
> >
> > Incidentally, does it need flush_dcache_page()?
>
> Yes, good catch.
next prev parent reply other threads:[~2023-01-11 16:02 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-01-09 17:56 [PATCH v2] fs/aio: Replace kmap{,_atomic}() with kmap_local_page() Fabio M. De Francesco
2023-01-11 0:11 ` Al Viro
2023-01-11 14:13 ` Jeff Moyer
2023-01-11 16:02 ` Al Viro [this message]
2023-01-11 16:20 ` Jeff Moyer
2023-01-11 16:29 ` Ira Weiny
2023-01-12 20:42 ` Fabio M. De Francesco
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