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SubjectRe: [PATCH 1/2] dax: fix O_DIRECT I/O to the last block of a blockdev
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This patch and the 2/2 patch don't seem to have gone anywhere.
Willy? or Ross?

-- ljk

On 8/14/2015 4:53 PM, Linda Knippers wrote:
> On 8/14/2015 4:15 PM, Jeff Moyer wrote:
>> commit bbab37ddc20b (block: Add support for DAX reads/writes to
>> block devices) caused a regression in mkfs.xfs. That utility
>> sets the block size of the device to the logical block size
>> using the BLKBSZSET ioctl, and then issues a single sector read
>> from the last sector of the device. This results in the dax_io
>> code trying to do a page-sized read from 512 bytes from the end
>> of the device. The result is -ERANGE being returned to userspace.
>>
>> The fix is to align the block to the page size before calling
>> get_block.
>>
>> Thanks to willy for simplifying my original patch.
>>
>> Signed-off-by: Jeff Moyer <jmoyer@redhat.com>
>
> Tested-by: Linda Knippers <linda.knippers@hp.com>
>
>> ---
>> fs/dax.c | 3 ++-
>> 1 file changed, 2 insertions(+), 1 deletion(-)
>>
>> diff --git a/fs/dax.c b/fs/dax.c
>> index a7f77e1..ef35a20 100644
>> --- a/fs/dax.c
>> +++ b/fs/dax.c
>> @@ -116,7 +116,8 @@ static ssize_t dax_io(struct inode *inode, struct iov_iter *iter,
>> unsigned len;
>> if (pos == max) {
>> unsigned blkbits = inode->i_blkbits;
>> - sector_t block = pos >> blkbits;
>> + long page = pos >> PAGE_SHIFT;
>> + sector_t block = page << (PAGE_SHIFT - blkbits);
>> unsigned first = pos - (block << blkbits);
>> long size;
>>
>>
>



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