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block: add helpers to run flush_dcache_page() against a bio and a request's pages

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Mtdblock driver doesn't call flush_dcache_page for pages in request.  So,
this causes problems on architectures where the icache doesn't fill from
the dcache or with dcache aliases.  The patch fixes this.

The ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE symbol was introduced to avoid
pointless empty cache-thrashing loops on architectures for which
flush_dcache_page() is a no-op.  Every architecture was provided with this
flush pages on architectires where ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE is
equal 1 or do nothing otherwise.

See "fix mtd_blkdevs problem with caches on some architectures" discussion
on LKML for more information.

Signed-off-by: Ilya Loginov <isloginov@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Peter Horton <phorton@bitbox.co.uk>
Cc: "Ed L. Cashin" <ecashin@coraid.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
This commit is contained in:
Ilya Loginov
2009-11-26 09:16:19 +01:00
committed by Jens Axboe
parent 3586e917f2
commit 2d4dc890b5
29 changed files with 83 additions and 0 deletions
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2
drivers/mtd/mtd_blkdevs.c
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@ -59,12 +59,14 @@ static int do_blktrans_request(struct mtd_blktrans_ops *tr,
for (; nsect > 0; nsect--, block++, buf += tr->blksize)
if (tr->readsect(dev, block, buf))
return -EIO;
rq_flush_dcache_pages(req);
return 0;
case WRITE:
if (!tr->writesect)
return -EIO;
rq_flush_dcache_pages(req);
for (; nsect > 0; nsect--, block++, buf += tr->blksize)
if (tr->writesect(dev, block, buf))
return -EIO;