linux-kernel - Re: [PATCH v11 3/9] iov_iter: introduce iov_iter_get_pages_[alloc

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Date:   Thu, 27 Oct 2022 08:22:57 -0600
From:   Logan Gunthorpe <logang@...tatee.com>
To:     Jay Fang <f.fangjian@...wei.com>, linux-kernel@...r.kernel.org,
        linux-nvme@...ts.infradead.org, linux-block@...r.kernel.org,
        linux-pci@...r.kernel.org, linux-mm@...ck.org
Cc:     Christoph Hellwig <hch@....de>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Dan Williams <dan.j.williams@...el.com>,
        Jason Gunthorpe <jgg@...pe.ca>,
        Christian König <christian.koenig@....com>,
        John Hubbard <jhubbard@...dia.com>,
        Don Dutile <ddutile@...hat.com>,
        Matthew Wilcox <willy@...radead.org>,
        Daniel Vetter <daniel.vetter@...ll.ch>,
        Minturn Dave B <dave.b.minturn@...el.com>,
        Jason Ekstrand <jason@...kstrand.net>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Xiong Jianxin <jianxin.xiong@...el.com>,
        Bjorn Helgaas <helgaas@...nel.org>,
        Ira Weiny <ira.weiny@...el.com>,
        Robin Murphy <robin.murphy@....com>,
        Martin Oliveira <martin.oliveira@...eticom.com>,
        Chaitanya Kulkarni <ckulkarnilinux@...il.com>,
        Ralph Campbell <rcampbell@...dia.com>,
        Stephen Bates <sbates@...thlin.com>
Subject: Re: [PATCH v11 3/9] iov_iter: introduce
 iov_iter_get_pages_[alloc_]flags()



On 2022-10-27 01:11, Jay Fang wrote:
> On 2022/10/22 1:41, Logan Gunthorpe wrote:
>> Add iov_iter_get_pages_flags() and iov_iter_get_pages_alloc_flags()
>> which take a flags argument that is passed to get_user_pages_fast().
>>
>> This is so that FOLL_PCI_P2PDMA can be passed when appropriate.
>>
>> Signed-off-by: Logan Gunthorpe <logang@...tatee.com>
>> Reviewed-by: Christoph Hellwig <hch@....de>
>> ---
>>  include/linux/uio.h |  6 ++++++
>>  lib/iov_iter.c      | 32 ++++++++++++++++++++++++--------
>>  2 files changed, 30 insertions(+), 8 deletions(-)
>>
>> diff --git a/include/linux/uio.h b/include/linux/uio.h
>> index 2e3134b14ffd..9ede533ce64c 100644
>> --- a/include/linux/uio.h
>> +++ b/include/linux/uio.h
>> @@ -247,8 +247,14 @@ void iov_iter_pipe(struct iov_iter *i, unsigned int direction, struct pipe_inode
>>  void iov_iter_discard(struct iov_iter *i, unsigned int direction, size_t count);
>>  void iov_iter_xarray(struct iov_iter *i, unsigned int direction, struct xarray *xarray,
>>  		     loff_t start, size_t count);
>> +ssize_t iov_iter_get_pages(struct iov_iter *i, struct page **pages,
>> +		size_t maxsize, unsigned maxpages, size_t *start,
>> +		unsigned gup_flags);
>>  ssize_t iov_iter_get_pages2(struct iov_iter *i, struct page **pages,
>>  			size_t maxsize, unsigned maxpages, size_t *start);
>> +ssize_t iov_iter_get_pages_alloc(struct iov_iter *i,
>> +		struct page ***pages, size_t maxsize, size_t *start,
>> +		unsigned gup_flags);
>>  ssize_t iov_iter_get_pages_alloc2(struct iov_iter *i, struct page ***pages,
>>  			size_t maxsize, size_t *start);
>>  int iov_iter_npages(const struct iov_iter *i, int maxpages);
>> diff --git a/lib/iov_iter.c b/lib/iov_iter.c
>> index c3ca28ca68a6..53efad017f3c 100644
>> --- a/lib/iov_iter.c
>> +++ b/lib/iov_iter.c
>> @@ -1430,7 +1430,8 @@ static struct page *first_bvec_segment(const struct iov_iter *i,
>>  
>>  static ssize_t __iov_iter_get_pages_alloc(struct iov_iter *i,
>>  		   struct page ***pages, size_t maxsize,
>> -		   unsigned int maxpages, size_t *start)
>> +		   unsigned int maxpages, size_t *start,
>> +		   unsigned int gup_flags)
> 
> Hi,
> found some checkpatch warnings, like this:
> WARNING: Prefer 'unsigned int' to bare use of 'unsigned'
> #50: FILE: lib/iov_iter.c:1497:
> +		   size_t *start, unsigned gup_flags)

We usually stick with the choices of the nearby code instead of
the warnings of checkpatch.

Thanks,

Logan