From: Chaitanya Kulkarni <Chaitanya.Kulkarni@wdc.com>
To: Christoph Hellwig <hch@lst.de>
Cc: Matthew Wilcox <willy@infradead.org>,
"linux-block@vger.kernel.org" <linux-block@vger.kernel.org>,
"linux-scsi@vger.kernel.org" <linux-scsi@vger.kernel.org>,
"target-devel@vger.kernel.org" <target-devel@vger.kernel.org>,
"linux-btrfs@vger.kernel.org" <linux-btrfs@vger.kernel.org>,
"axboe@kernel.dk" <axboe@kernel.dk>,
"mb@lightnvm.io" <mb@lightnvm.io>,
"martin.petersen@oracle.com" <martin.petersen@oracle.com>,
"clm@fb.com" <clm@fb.com>,
"josef@toxicpanda.com" <josef@toxicpanda.com>,
"dsterba@suse.com" <dsterba@suse.com>,
Johannes Thumshirn <Johannes.Thumshirn@wdc.com>,
"ming.lei@redhat.com" <ming.lei@redhat.com>,
"osandov@fb.com" <osandov@fb.com>,
"jefflexu@linux.alibaba.com" <jefflexu@linux.alibaba.com>
Subject: Re: [RFC PATCH 0/8] block: fix bio_add_XXX_page() return type
Date: Wed, 26 May 2021 02:55:57 +0000 [thread overview]
Message-ID: <BYAPR04MB49650508F2C5A4EA3B576D5286249@BYAPR04MB4965.namprd04.prod.outlook.com> (raw)
In-Reply-To: 20210524073527.GA24302@lst.de
Christoph,
On 5/24/21 00:35, Christoph Hellwig wrote:
> On Fri, May 21, 2021 at 12:30:45PM +0100, Matthew Wilcox wrote:
>> On Wed, May 19, 2021 at 11:22:47PM -0700, Chaitanya Kulkarni wrote:
>>> The helper functions bio_add_XXX_page() returns the length which is
>>> unsigned int but the return type of those functions is defined
>>> as int instead of unsigned int.
>> I've been thinking about this for a few weeks as part of the folio
>> patches:
>>
>> https://lore.kernel.org/linux-fsdevel/20210505150628.111735-72-willy@infradead.org/
>>
>> - len and off are measured in bytes
>> - neither are permitted to be negative
>> - for efficiency we only permit them to be up to 4GB
>>
>> I therefore believe the correct type for these parameters to be size_t,
>> and we should range-check them if they're too large. they should
>> actually always fit within the page that they're associated with, but
>> people do allocate non-compound pages and i'm not trying to break that
>> today.
>>
>> using size_t makes it clear that these are byte counts, not (eg) sector
>> counts. i do think it's good to make the return value unsigned so we
>> don't have people expecting a negative errno on failure.
> I think the right type is bool. We always return either 0 or the full
> length we tried to add. Instead of optimizing for a partial add (which
> only makes sense for bio_add_hw_page anyway), I'd rather make the
> interface as simple as possible.
>
Is above comment is on this series or on the API present in the folio
patches [1] ?
Since if we change the return type to bool for the functions in
question [2] in this series we also need to modify the callers, I'm not sure
that is worth it though.
Please confirm.
[1]
https://lore.kernel.org/linux-fsdevel/20210505150628.111735-72-willy@infradead.org/
[2]
bio_add_hw_page()
bio_add_pc_page()
bio_add_zone_append_page()
bio_add page()
next prev parent reply other threads:[~2021-05-26 2:56 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-20 6:22 [RFC PATCH 0/8] block: fix bio_add_XXX_page() return type Chaitanya Kulkarni
2021-05-20 6:22 ` [RFC PATCH 1/8] block: fix return type of bio_add_hw_page() Chaitanya Kulkarni
2021-05-20 6:22 ` [RFC PATCH 2/8] block: fix return type of bio_add_pc_page() Chaitanya Kulkarni
2021-05-20 6:22 ` [RFC PATCH 3/8] block: fix return type of bio_add_zone_append_page Chaitanya Kulkarni
2021-05-20 6:22 ` [RFC PATCH 4/8] block: fix return type of bio_add_page() Chaitanya Kulkarni
2021-05-20 6:22 ` [RFC PATCH 5/8] lightnvm: fix variable type pblk-core Chaitanya Kulkarni
2021-05-20 6:22 ` [RFC PATCH 6/8] pscsi: fix variable type pscsi_map_sg Chaitanya Kulkarni
2021-05-20 6:22 ` [RFC PATCH 7/8] btrfs: fix variable type in btrfs_bio_add_page Chaitanya Kulkarni
2021-05-20 6:22 ` [RFC PATCH 8/8] block: fix variable type for zero pages Chaitanya Kulkarni
2021-05-21 10:25 ` [RFC PATCH 0/8] block: fix bio_add_XXX_page() return type Johannes Thumshirn
2021-05-21 21:37 ` Chaitanya Kulkarni
2021-05-21 22:37 ` Omar Sandoval
2021-05-21 23:25 ` Chaitanya Kulkarni
2021-05-21 11:30 ` Matthew Wilcox
2021-05-21 21:51 ` Chaitanya Kulkarni
2021-05-24 7:35 ` Christoph Hellwig
2021-05-24 13:29 ` Matthew Wilcox
2021-05-26 2:55 ` Chaitanya Kulkarni [this message]
2021-05-27 11:43 ` Christoph Hellwig
2021-05-27 17:43 ` Chaitanya Kulkarni
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