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Message-ID: <Y73+xKXDELSd14p1@ZenIV>
Date: Wed, 11 Jan 2023 00:11:48 +0000
From: Al Viro <viro@...iv.linux.org.uk>
To: "Fabio M. De Francesco" <fmdefrancesco@...il.com>
Cc: Benjamin LaHaise <bcrl@...ck.org>, linux-aio@...ck.org,
linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
"Venkataramanan, Anirudh" <anirudh.venkataramanan@...el.com>,
Ira Weiny <ira.weiny@...el.com>, Jeff Moyer <jmoyer@...hat.com>
Subject: Re: [PATCH v2] fs/aio: Replace kmap{,_atomic}() with
kmap_local_page()
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...
>
> 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()?
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