From: Christoph Hellwig <hch@infradead.org>
To: David Howells <dhowells@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>,
Christoph Hellwig <hch@infradead.org>,
Matthew Wilcox <willy@infradead.org>,
Jens Axboe <axboe@kernel.dk>, Jan Kara <jack@suse.cz>,
Jeff Layton <jlayton@kernel.org>,
Logan Gunthorpe <logang@deltatee.com>,
linux-fsdevel@vger.kernel.org, linux-block@vger.kernel.org,
linux-kernel@vger.kernel.org, Christoph Hellwig <hch@lst.de>,
linux-mm@kvack.org
Subject: Re: [PATCH v8 10/10] mm: Renumber FOLL_PIN and FOLL_GET down
Date: Mon, 23 Jan 2023 10:25:25 -0800 [thread overview]
Message-ID: <Y87RFUQcN4my7pa9@infradead.org> (raw)
In-Reply-To: <20230123173007.325544-11-dhowells@redhat.com>
On Mon, Jan 23, 2023 at 05:30:07PM +0000, David Howells wrote:
> Renumber FOLL_PIN and FOLL_GET down to bit 0 and 1 respectively so that
> they are coincidentally the same as BIO_PAGE_PINNED and BIO_PAGE_REFFED and
> also so that they can be stored in the bottom two bits of a page pointer
> (something I'm looking at for zerocopy socket fragments).
>
> (Note that BIO_PAGE_REFFED should probably be got rid of at some point,
> hence why FOLL_PIN is at 0.)
>
> Also renumber down the other FOLL_* flags to close the gaps.
Taking the risk of having a long bikeshed: I much prefer (1U << bitnr)
style definition that make it obvious where there are holes, but
otherwise:
Reviewed-by: Christoph Hellwig <hch@lst.de>
next prev parent reply other threads:[~2023-01-23 18:25 UTC|newest]
Thread overview: 39+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20230123173007.325544-1-dhowells@redhat.com>
2023-01-23 17:29 ` [PATCH v8 02/10] iov_iter: Add a function to extract a page list from an iterator David Howells
2023-01-23 18:21 ` Christoph Hellwig
2023-01-24 14:27 ` David Hildenbrand
2023-01-24 14:35 ` David Howells
2023-01-24 14:37 ` David Hildenbrand
2023-01-24 14:45 ` David Howells
2023-01-24 14:52 ` David Hildenbrand
2023-01-23 17:30 ` [PATCH v8 03/10] mm: Provide a helper to drop a pin/ref on a page David Howells
2023-01-23 18:21 ` Christoph Hellwig
2023-01-24 3:03 ` John Hubbard
2023-01-24 14:28 ` David Hildenbrand
2023-01-24 14:41 ` David Howells
2023-01-24 14:52 ` Christoph Hellwig
2023-01-24 14:53 ` David Hildenbrand
2023-01-24 15:04 ` David Howells
2023-01-23 17:30 ` [PATCH v8 10/10] mm: Renumber FOLL_PIN and FOLL_GET down David Howells
2023-01-23 18:25 ` Christoph Hellwig [this message]
2023-01-24 3:08 ` John Hubbard
2023-01-24 3:11 ` John Hubbard
2023-01-24 13:13 ` Jason Gunthorpe
2023-01-24 13:18 ` Christoph Hellwig
2023-01-24 13:43 ` Jason Gunthorpe
2023-01-24 13:40 ` David Howells
2023-01-24 13:46 ` David Howells
2023-01-24 13:47 ` Jason Gunthorpe
2023-01-24 13:57 ` David Howells
2023-01-24 14:00 ` Jason Gunthorpe
2023-01-24 14:02 ` Christoph Hellwig
2023-01-24 14:11 ` David Howells
2023-01-24 14:14 ` Jason Gunthorpe
2023-01-24 14:27 ` David Howells
2023-01-24 14:31 ` Jason Gunthorpe
2023-01-24 14:59 ` David Howells
2023-01-24 15:06 ` Jason Gunthorpe
2023-01-24 15:12 ` David Howells
2023-01-24 14:12 ` David Howells
2023-01-24 14:13 ` Christoph Hellwig
2023-01-24 14:25 ` David Howells
2023-01-24 7:05 ` David Howells
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