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SubjectRe: [PATCH 3/6] direct-io: add support for write stream IDs
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On Wed, Mar 25, 2015 at 7:26 AM, Jens Axboe <axboe@kernel.dk> wrote:
> On 03/24/2015 08:43 PM, Dave Chinner wrote:
>>
>> On Tue, Mar 24, 2015 at 09:27:00AM -0600, Jens Axboe wrote:
>>>
>>> Get the streamid from the file, if any, and set it on the bio.
>>>
>>> Signed-off-by: Jens Axboe <axboe@fb.com>
>>> ---
>>> fs/direct-io.c | 4 ++++
>>> 1 file changed, 4 insertions(+)
>>>
>>> diff --git a/fs/direct-io.c b/fs/direct-io.c
>>> index e181b6b2e297..5d2750346451 100644
>>> --- a/fs/direct-io.c
>>> +++ b/fs/direct-io.c
>>> @@ -77,6 +77,7 @@ struct dio_submit {
>>> int reap_counter; /* rate limit reaping */
>>> sector_t final_block_in_request;/* doesn't change */
>>> int boundary; /* prev block is at a boundary */
>>> + int streamid; /* Write stream ID */
>>> get_block_t *get_block; /* block mapping function */
>>> dio_submit_t *submit_io; /* IO submition function */
>>>
>>> @@ -372,6 +373,8 @@ dio_bio_alloc(struct dio *dio, struct dio_submit
>>> *sdio,
>>>
>>> sdio->bio = bio;
>>> sdio->logical_offset_in_bio = sdio->cur_page_fs_offset;
>>> +
>>> + bio_set_streamid(bio, sdio->streamid);
>>> }
>>>
>>> /*
>>> @@ -1205,6 +1208,7 @@ do_blockdev_direct_IO(int rw, struct kiocb *iocb,
>>> struct inode *inode,
>>> sdio.blkbits = blkbits;
>>> sdio.blkfactor = i_blkbits - blkbits;
>>> sdio.block_in_file = offset >> blkbits;
>>> + sdio.streamid = iocb->ki_filp->f_streamid;
>>
>>
>> If iocb->ki_filp->f_streamid is not set, then it should fall back to
>> whatever is set on the inode->i_streamid.

Why should do the fall back?

>
>
> Good point, agree. Will make that change.

Hi Jens,

That change causes problem for direct IO, for example

process 1:
fd = open("/dev/nvme0n1", O_DIRECT...);
//set stream_id 1
fadvise(fd, 1, 0, POSIX_FADV_STREAMID);
pwrite(fd, ....);

process 2:
fd = open("/dev/nvme0n1", O_DIRECT...);
//should be legacy stream_id 0
pwrite(fd, ....);

But now process 2 also see stream_id 1, which is wrong.

Thanks,
Ming

>
>
> --
> Jens Axboe


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