Re: [PATCH v2 1/2] fs,block: Introduce RWF_ZONE_APPEND and handling in direct IO path

From: Kanchan Joshi <joshi.k@samsung.com>
To: Damien Le Moal <Damien.LeMoal@wdc.com>
Cc: "axboe@kernel.dk" <axboe@kernel.dk>,
	"viro@zeniv.linux.org.uk" <viro@zeniv.linux.org.uk>,
	"bcrl@kvack.org" <bcrl@kvack.org>,
	"asml.silence@gmail.com" <asml.silence@gmail.com>,
	"hch@infradead.org" <hch@infradead.org>,
	"linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>,
	"mb@lightnvm.io" <mb@lightnvm.io>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"linux-aio@kvack.org" <linux-aio@kvack.org>,
	"io-uring@vger.kernel.org" <io-uring@vger.kernel.org>,
	"linux-block@vger.kernel.org" <linux-block@vger.kernel.org>,
	"selvakuma.s1@samsung.com" <selvakuma.s1@samsung.com>,
	"nj.shetty@samsung.com" <nj.shetty@samsung.com>,
	"javier.gonz@samsung.com" <javier.gonz@samsung.com>,
	Arnav Dawn <a.dawn@samsung.com>
Subject: Re: [PATCH v2 1/2] fs,block: Introduce RWF_ZONE_APPEND and handling in direct IO path
Date: Tue, 30 Jun 2020 00:02:02 +0530	[thread overview]
Message-ID: <20200629183202.GA24003@test-zns> (raw)
In-Reply-To: <CY4PR04MB37511FB1D3B3491A2CED5470E7930@CY4PR04MB3751.namprd04.prod.outlook.com>

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On Fri, Jun 26, 2020 at 02:50:20AM +0000, Damien Le Moal wrote:
>On 2020/06/26 2:18, Kanchan Joshi wrote:
>> Introduce RWF_ZONE_APPEND flag to represent zone-append. User-space
>> sends this with write. Add IOCB_ZONE_APPEND which is set in
>> kiocb->ki_flags on receiving RWF_ZONE_APPEND.
>> Make direct IO submission path use IOCB_ZONE_APPEND to send bio with
>> append op. Direct IO completion returns zone-relative offset, in sector
>> unit, to upper layer using kiocb->ki_complete interface.
>> Report error if zone-append is requested on regular file or on sync
>> kiocb (i.e. one without ki_complete).
>>
>> Signed-off-by: Kanchan Joshi <joshi.k@samsung.com>
>> Signed-off-by: SelvaKumar S <selvakuma.s1@samsung.com>
>> Signed-off-by: Arnav Dawn <a.dawn@samsung.com>
>> Signed-off-by: Nitesh Shetty <nj.shetty@samsung.com>
>> Signed-off-by: Javier Gonzalez <javier.gonz@samsung.com>
>> ---
>>  fs/block_dev.c          | 28 ++++++++++++++++++++++++----
>>  include/linux/fs.h      |  9 +++++++++
>>  include/uapi/linux/fs.h |  5 ++++-
>>  3 files changed, 37 insertions(+), 5 deletions(-)
>>
>> diff --git a/fs/block_dev.c b/fs/block_dev.c
>> index 47860e5..5180268 100644
>> --- a/fs/block_dev.c
>> +++ b/fs/block_dev.c
>> @@ -185,6 +185,10 @@ static unsigned int dio_bio_write_op(struct kiocb *iocb)
>>  	/* avoid the need for a I/O completion work item */
>>  	if (iocb->ki_flags & IOCB_DSYNC)
>>  		op |= REQ_FUA;
>> +
>> +	if (iocb->ki_flags & IOCB_ZONE_APPEND)
>> +		op |= REQ_OP_ZONE_APPEND;
>
>This is wrong. REQ_OP_WRITE is already set in the declaration of "op". How can
>this work ?
REQ_OP_ZONE_APPEND will override the REQ_WRITE op, while previously set op
flags (REQ_FUA etc.) will be retained. But yes, this can be made to look
cleaner.
V3 will include the other changes you pointed out. Thanks for the review.


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