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From:   Damien Le Moal <Damien.LeMoal@wdc.com>
To:     Kanchan Joshi <joshi.k@samsung.com>
CC:     "axboe@kernel.dk" <axboe@kernel.dk>,
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        Arnav Dawn <a.dawn@samsung.com>
Subject: Re: [PATCH v2 1/2] fs,block: Introduce RWF_ZONE_APPEND and handling
 in direct IO path
Thread-Topic: [PATCH v2 1/2] fs,block: Introduce RWF_ZONE_APPEND and handling
 in direct IO path
Thread-Index: AQHWSxStAvYl2c5t2kCK+9TjcP8ZXw==
Date:   Tue, 30 Jun 2020 00:37:07 +0000
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On 2020/06/30 3:35, Kanchan Joshi wrote:=0A=
> On Fri, Jun 26, 2020 at 02:50:20AM +0000, Damien Le Moal wrote:=0A=
>> On 2020/06/26 2:18, Kanchan Joshi wrote:=0A=
>>> Introduce RWF_ZONE_APPEND flag to represent zone-append. User-space=0A=
>>> sends this with write. Add IOCB_ZONE_APPEND which is set in=0A=
>>> kiocb->ki_flags on receiving RWF_ZONE_APPEND.=0A=
>>> Make direct IO submission path use IOCB_ZONE_APPEND to send bio with=0A=
>>> append op. Direct IO completion returns zone-relative offset, in sector=
=0A=
>>> unit, to upper layer using kiocb->ki_complete interface.=0A=
>>> Report error if zone-append is requested on regular file or on sync=0A=
>>> kiocb (i.e. one without ki_complete).=0A=
>>>=0A=
>>> Signed-off-by: Kanchan Joshi <joshi.k@samsung.com>=0A=
>>> Signed-off-by: SelvaKumar S <selvakuma.s1@samsung.com>=0A=
>>> Signed-off-by: Arnav Dawn <a.dawn@samsung.com>=0A=
>>> Signed-off-by: Nitesh Shetty <nj.shetty@samsung.com>=0A=
>>> Signed-off-by: Javier Gonzalez <javier.gonz@samsung.com>=0A=
>>> ---=0A=
>>>  fs/block_dev.c          | 28 ++++++++++++++++++++++++----=0A=
>>>  include/linux/fs.h      |  9 +++++++++=0A=
>>>  include/uapi/linux/fs.h |  5 ++++-=0A=
>>>  3 files changed, 37 insertions(+), 5 deletions(-)=0A=
>>>=0A=
>>> diff --git a/fs/block_dev.c b/fs/block_dev.c=0A=
>>> index 47860e5..5180268 100644=0A=
>>> --- a/fs/block_dev.c=0A=
>>> +++ b/fs/block_dev.c=0A=
>>> @@ -185,6 +185,10 @@ static unsigned int dio_bio_write_op(struct kiocb =
*iocb)=0A=
>>>  	/* avoid the need for a I/O completion work item */=0A=
>>>  	if (iocb->ki_flags & IOCB_DSYNC)=0A=
>>>  		op |=3D REQ_FUA;=0A=
>>> +=0A=
>>> +	if (iocb->ki_flags & IOCB_ZONE_APPEND)=0A=
>>> +		op |=3D REQ_OP_ZONE_APPEND;=0A=
>>=0A=
>> This is wrong. REQ_OP_WRITE is already set in the declaration of "op". H=
ow can=0A=
>> this work ?=0A=
> REQ_OP_ZONE_APPEND will override the REQ_WRITE op, while previously set o=
p=0A=
> flags (REQ_FUA etc.) will be retained. But yes, this can be made to look=
=0A=
> cleaner.=0A=
> V3 will include the other changes you pointed out. Thanks for the review.=
=0A=
> =0A=
=0A=
REQ_OP_WRITE and REQ_OP_ZONE_APPEND are different bits, so there is no=0A=
"override". A well formed BIO bi_opf is one op+flags. Specifying multiple O=
P=0A=
codes does not make sense.=0A=
=0A=
-- =0A=
Damien Le Moal=0A=
Western Digital Research=0A=