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From: John Hubbard <jhubbard@nvidia.com>
To: Christoph Hellwig <hch@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	Jens Axboe <axboe@kernel.dk>,
	Alexander Viro <viro@zeniv.linux.org.uk>,
	Miklos Szeredi <miklos@szeredi.hu>,
	"Darrick J . Wong" <djwong@kernel.org>,
	Trond Myklebust <trond.myklebust@hammerspace.com>,
	Anna Schumaker <anna@kernel.org>, Jan Kara <jack@suse.cz>,
	David Hildenbrand <david@redhat.com>,
	Logan Gunthorpe <logang@deltatee.com>,
	linux-block@vger.kernel.org, linux-fsdevel@vger.kernel.org,
	linux-xfs@vger.kernel.org, linux-nfs@vger.kernel.org,
	linux-mm@kvack.org, LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v2 4/7] iov_iter: new iov_iter_pin_pages*() routines
Date: Tue, 6 Sep 2022 00:44:28 -0700	[thread overview]
Message-ID: <103fe662-3dc8-35cb-1a68-dda8af95c518@nvidia.com> (raw)
In-Reply-To: <YxbtF1O8+kXhTNaj@infradead.org>

On 9/5/22 23:47, Christoph Hellwig wrote:
> I'd it one step back.  For BVECS we never need a get or pin.  The
> block layer already does this, an the other callers should as well.
> For KVEC the same is true.  For PIPE and xarray as you pointed out
> we can probably just do the pin, it is not like these are performance
> paths.
> 
> So, I'd suggest to:
> 
>  - factor out the user backed and bvec cases from
>    __iov_iter_get_pages_alloc into helper just to keep
>    __iov_iter_get_pages_alloc readable.

OK, that part is clear.

>  - for the pin case don't use the existing bvec helper at all, but
>    copy the logic for the block layer for not pinning.

I'm almost, but not quite sure I get the idea above. Overall, what
happens to bvec pages? Leave the get_page() pin in place for FOLL_GET
(or USE_FOLL_GET), I suppose, but do...what, for FOLL_PIN callers?

thanks,

-- 
John Hubbard
NVIDIA


  reply	other threads:[~2022-09-06  7:44 UTC|newest]

Thread overview: 55+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-08-31  4:18 [PATCH v2 0/7] convert most filesystems to pin_user_pages_fast() John Hubbard
2022-08-31  4:18 ` [PATCH v2 1/7] mm: change release_pages() to use unsigned long for npages John Hubbard
2022-08-31  4:18 ` [PATCH v2 2/7] mm/gup: introduce pin_user_page() John Hubbard
2022-09-06  6:37   ` Christoph Hellwig
2022-09-06  7:12     ` John Hubbard
2022-08-31  4:18 ` [PATCH v2 3/7] block: add dio_w_*() wrappers for pin, unpin user pages John Hubbard
2022-08-31  4:18 ` [PATCH v2 4/7] iov_iter: new iov_iter_pin_pages*() routines John Hubbard
2022-09-01  0:42   ` Al Viro
2022-09-01  1:48     ` John Hubbard
2022-09-06  6:47   ` Christoph Hellwig
2022-09-06  7:44     ` John Hubbard [this message]
2022-09-06  7:48       ` Christoph Hellwig
2022-09-06  7:58         ` John Hubbard
2022-09-07  8:50           ` Christoph Hellwig
2022-09-06 10:21         ` Jan Kara
2022-09-07  8:45           ` Christoph Hellwig
2022-09-14  3:51             ` Al Viro
2022-09-14 14:52               ` Jan Kara
2022-09-14 16:42                 ` Al Viro
2022-09-15  8:16                   ` Jan Kara
2022-09-16  1:55                     ` Al Viro
2022-09-20  5:02                       ` Al Viro
2022-09-22 14:36                         ` Christoph Hellwig
2022-09-22 14:43                           ` David Hildenbrand
2022-09-22 14:45                             ` Christoph Hellwig
2022-09-22  2:22                     ` Al Viro
2022-09-22  6:09                       ` John Hubbard
2022-09-22 11:29                         ` Jan Kara
2022-09-23  3:19                           ` Al Viro
2022-09-23  4:05                             ` John Hubbard
2022-09-23  8:39                               ` Christoph Hellwig
2022-09-23 12:22                               ` Jan Kara
2022-09-23  4:34                           ` John Hubbard
2022-09-22 14:38                       ` Christoph Hellwig
2022-09-23  4:22                         ` Al Viro
2022-09-23  8:44                           ` Christoph Hellwig
2022-09-23 16:13                             ` Al Viro
2022-09-26 15:53                               ` Christoph Hellwig
2022-09-26 19:55                                 ` Al Viro
2022-09-22 14:31               ` Christoph Hellwig
2022-09-22 14:36                 ` Al Viro
2022-08-31  4:18 ` [PATCH v2 5/7] block, bio, fs: convert most filesystems to pin_user_pages_fast() John Hubbard
2022-09-06  6:48   ` Christoph Hellwig
2022-09-06  7:15     ` John Hubbard
2022-08-31  4:18 ` [PATCH v2 6/7] NFS: direct-io: convert to FOLL_PIN pages John Hubbard
2022-09-06  6:49   ` Christoph Hellwig
2022-09-06  7:16     ` John Hubbard
2022-08-31  4:18 ` [PATCH v2 7/7] fuse: convert direct IO paths to use FOLL_PIN John Hubbard
2022-08-31 10:37   ` Miklos Szeredi
2022-09-01  1:33     ` John Hubbard
2022-09-06  6:36 ` [PATCH v2 0/7] convert most filesystems to pin_user_pages_fast() Christoph Hellwig
2022-09-06  7:10   ` John Hubbard
2022-09-06  7:22     ` Christoph Hellwig
2022-09-06  7:37       ` John Hubbard
2022-09-06  7:46         ` Christoph Hellwig

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