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Message-ID: <56ABA561.9070606@fb.com>
Date: Fri, 29 Jan 2016 10:46:09 -0700
From: Jens Axboe <axboe@...com>
To: Dan Williams <dan.j.williams@...el.com>,
<linux-block@...r.kernel.org>
CC: <linux-nvdimm@...ts.01.org>, Dave Chinner <david@...morbit.com>,
<linux-kernel@...r.kernel.org>, Christoph Hellwig <hch@....de>,
Jeff Moyer <jmoyer@...hat.com>, Jan Kara <jack@...e.com>,
<linux-fsdevel@...r.kernel.org>,
Matthew Wilcox <willy@...ux.intel.com>,
Andrew Morton <akpm@...ux-foundation.org>,
Ross Zwisler <ross.zwisler@...ux.intel.com>
Subject: Re: [PATCH 2/2] block: use DAX for partition table reads
On 01/29/2016 08:18 AM, Dan Williams wrote:
> +unsigned char *read_dev_sector(struct block_device *bdev, sector_t n, Sector *p)
> +{
> struct page *page;
>
> - page = read_mapping_page(mapping, (pgoff_t)(n >> (PAGE_CACHE_SHIFT-9)),
> - NULL);
> + /* don't populate page cache for dax capable devices */
> + if (IS_DAX(bdev->bd_inode))
> + page = read_dax_sector(bdev, n);
> + else
> + page = read_pagecache_sector(bdev, n);
> +
Fall back to non-dax, if dax fails?
> +struct page *read_dax_sector(struct block_device *bdev, sector_t n)
> +{
> + struct page *page = __page_cache_alloc(GFP_KERNEL | __GFP_COLD);
Why isn't that just alloc_pages()?
--
Jens Axboe
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