Re: [PATCH 2/2] block: use DAX for partition table reads

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



On Fri, Jan 29, 2016 at 9:46 AM, Jens Axboe <axboe@xxxxxx> wrote:
> 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?

I think we need to fail hard otherwise we're back to the original
problem of confusing the dax code that expects to find an empty page
cache.

>
>> +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()?

Just for symmetry with the same allocation that the pagecache path
makes, but alloc_pages() works too...
--
To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html



[Index of Archives]     [Linux Ext4 Filesystem]     [Union Filesystem]     [Filesystem Testing]     [Ceph Users]     [Ecryptfs]     [AutoFS]     [Kernel Newbies]     [Share Photos]     [Security]     [Netfilter]     [Bugtraq]     [Yosemite News]     [MIPS Linux]     [ARM Linux]     [Linux Security]     [Linux Cachefs]     [Reiser Filesystem]     [Linux RAID]     [Samba]     [Device Mapper]     [CEPH Development]
  Powered by Linux