From: John Hubbard <jhubbard@nvidia.com>
To: Jan Kara <jack@suse.cz>
Cc: Al Viro <viro@zeniv.linux.org.uk>,
Andrew Morton <akpm@linux-foundation.org>,
Jens Axboe <axboe@kernel.dk>, Miklos Szeredi <miklos@szeredi.hu>,
Christoph Hellwig <hch@infradead.org>,
"Darrick J . Wong" <djwong@kernel.org>,
Trond Myklebust <trond.myklebust@hammerspace.com>,
Anna Schumaker <anna@kernel.org>,
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 5/6] NFS: direct-io: convert to FOLL_PIN pages
Date: Wed, 31 Aug 2022 11:02:45 -0700 [thread overview]
Message-ID: <c66b13a6-b9d7-381a-4fb8-cc5e8b833ac5@nvidia.com> (raw)
In-Reply-To: <20220831094349.boln4jjajkdtykx3@quack3>
On 8/31/22 02:43, Jan Kara wrote:
>> OK, thanks, that looks viable. So, that approach assumes that the
>> remaining two cases in __iov_iter_get_pages_alloc() will never end up
>> being released via bio_release_pages():
>>
>> iov_iter_is_pipe(i)
>> iov_iter_is_xarray(i)
>>
>> I'm actually a little worried about ITER_XARRAY, which is a recent addition.
>> It seems to be used in ways that are similar to ITER_BVEC, and cephfs is
>> using it. It's probably OK for now, for this series, which doesn't yet
>> convert cephfs.
>
> So after looking into that a bit more, I think a clean approach would be to
> provide iov_iter_pin_pages2() and iov_iter_pages_alloc2(), under the hood
> in __iov_iter_get_pages_alloc() make sure we use pin_user_page() instead of
> get_page() in all the cases (using this in pipe_get_pages() and
> iter_xarray_get_pages() is easy) and then make all bio handling use the
> pinning variants for iters. I think at least iov_iter_is_pipe() case needs
> to be handled as well because as I wrote above, pipe pages can enter direct
> IO code e.g. for splice(2).
>
OK, yes.
> Also I think that all iov_iter_get_pages2() (or the _alloc2 variant) users
> actually do want the "pin page" semantics in the end (they are accessing
> page contents) so eventually we should convert them all to
> iov_iter_pin_pages2() and remove iov_iter_get_pages2() altogether. But this
> will take some more conversion work with networking etc. so I'd start with
> converting bios only.
>
> Honza
I'll give this approach a spin, thanks very much for the guidance!
thanks,
--
John Hubbard
NVIDIA
next prev parent reply other threads:[~2022-08-31 18:02 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-08-27 8:36 [PATCH 0/6] convert most filesystems to pin_user_pages_fast() John Hubbard
2022-08-27 8:36 ` [PATCH 1/6] mm/gup: introduce pin_user_page() John Hubbard
2022-08-29 12:07 ` David Hildenbrand
2022-08-29 19:33 ` John Hubbard
2022-08-30 12:17 ` David Hildenbrand
2022-08-30 21:42 ` John Hubbard
2022-08-31 0:06 ` John Hubbard
2022-08-27 8:36 ` [PATCH 2/6] block: add dio_w_*() wrappers for pin, unpin user pages John Hubbard
2022-08-27 22:27 ` Andrew Morton
2022-08-27 23:59 ` John Hubbard
2022-08-28 0:12 ` Andrew Morton
2022-08-28 0:31 ` John Hubbard
2022-08-28 1:07 ` John Hubbard
2022-08-27 8:36 ` [PATCH 3/6] iov_iter: new iov_iter_pin_pages*() routines John Hubbard
2022-08-27 22:46 ` Al Viro
2022-08-27 22:48 ` John Hubbard
2022-08-27 8:36 ` [PATCH 4/6] block, bio, fs: convert most filesystems to pin_user_pages_fast() John Hubbard
2022-08-27 8:36 ` [PATCH 5/6] NFS: direct-io: convert to FOLL_PIN pages John Hubbard
2022-08-27 22:48 ` Al Viro
2022-08-27 23:55 ` John Hubbard
2022-08-28 0:38 ` Al Viro
2022-08-28 0:39 ` Al Viro
2022-08-28 0:46 ` John Hubbard
2022-08-29 4:59 ` John Hubbard
2022-08-29 16:08 ` Jan Kara
2022-08-29 19:59 ` John Hubbard
2022-08-31 9:43 ` Jan Kara
2022-08-31 18:02 ` John Hubbard [this message]
2022-09-01 0:38 ` Al Viro
2022-09-01 9:06 ` Jan Kara
2022-08-27 8:36 ` [PATCH 6/6] fuse: convert direct IO paths to use FOLL_PIN John Hubbard
-- strict thread matches above, loose matches on Subject: below --
2022-02-27 9:34 [PATCH 0/6] block, fs: convert most Direct IO cases to FOLL_PIN jhubbard.send.patches
2022-02-27 9:34 ` [PATCH 5/6] NFS: direct-io: convert to FOLL_PIN pages jhubbard.send.patches
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