From: David Howells <dhowells@redhat.com>
To: Christoph Hellwig <hch@infradead.org>
Cc: dhowells@redhat.com, Al Viro <viro@zeniv.linux.org.uk>,
Jens Axboe <axboe@kernel.dk>, Jan Kara <jack@suse.cz>,
Christoph Hellwig <hch@lst.de>,
Matthew Wilcox <willy@infradead.org>,
Logan Gunthorpe <logang@deltatee.com>,
linux-block@vger.kernel.org, Jeff Layton <jlayton@kernel.org>,
linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v5 8/9] iov_iter, block: Make bio structs pin pages rather than ref'ing if appropriate
Date: Thu, 12 Jan 2023 10:28:41 +0000 [thread overview]
Message-ID: <15237.1673519321@warthog.procyon.org.uk> (raw)
In-Reply-To: <Y7+6YVkhZsvdW+Hr@infradead.org>
Christoph Hellwig <hch@infradead.org> wrote:
> if (cleanup_mode & FOLL_GET) {
> WARN_ON_ONCE(bio_test_flag(bio, BIO_PAGE_PINNED));
> bio_set_flag(bio, BIO_PAGE_REFFED);
> }
> if (cleanup_mode & FOLL_PIN) {
> WARN_ON_ONCE(bio_test_flag(bio, BIO_PAGE_REFFED));
> bio_set_flag(bio, BIO_PAGE_PINNED);
> }
That won't necessarily work as you might get back cleanup_mode == 0, in which
case both flags are cleared - and neither warning will trip on the next
addition.
I could change it so that rather than using a pair of flags, it uses a
four-state variable (which can be stored in bi_flags): BIO_PAGE_DEFAULT,
BIO_PAGE_REFFED, BIO_PAGE_PINNED, BIO_PAGE_NO_CLEANUP, say.
Or I could add an extra flag to say that the setting is locked. Or we could
just live with the scenario I outlined possibly happening.
David
next prev parent reply other threads:[~2023-01-12 10:35 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-01-11 14:27 [PATCH v5 0/9] iov_iter: Add extraction helpers David Howells
2023-01-11 14:27 ` [PATCH v5 1/9] iov_iter: Change the direction macros into an enum David Howells
2023-01-11 14:27 ` [PATCH v5 2/9] iov_iter: Use the direction in the iterator functions David Howells
2023-01-11 14:27 ` [PATCH v5 3/9] iov_iter: Use IOCB/IOMAP_WRITE if available rather than iterator direction David Howells
2023-01-12 7:54 ` Christoph Hellwig
2023-01-12 10:31 ` David Howells
2023-01-12 14:08 ` Christoph Hellwig
2023-01-12 17:37 ` Al Viro
2023-01-12 21:49 ` Bart Van Assche
2023-01-13 5:32 ` Christoph Hellwig
2023-01-14 1:33 ` Martin K. Petersen
2023-01-14 1:34 ` Martin K. Petersen
2023-01-14 1:58 ` Al Viro
2023-01-13 5:30 ` Christoph Hellwig
2023-01-12 21:56 ` Al Viro
2023-01-13 5:33 ` Christoph Hellwig
2023-01-11 14:28 ` [PATCH v5 4/9] iov_iter: Add a function to extract a page list from an iterator David Howells
2023-01-12 7:55 ` Christoph Hellwig
2023-01-12 21:15 ` Al Viro
2023-01-12 21:36 ` Al Viro
2023-01-13 5:26 ` Christoph Hellwig
2023-01-11 14:28 ` [PATCH v5 5/9] netfs: Add a function to extract a UBUF or IOVEC into a BVEC iterator David Howells
2023-01-11 14:28 ` [PATCH v5 6/9] netfs: Add a function to extract an iterator into a scatterlist David Howells
2023-01-11 14:28 ` [PATCH v5 7/9] bio: Rename BIO_NO_PAGE_REF to BIO_PAGE_REFFED and invert the meaning David Howells
2023-01-12 7:32 ` Christoph Hellwig
2023-01-11 14:28 ` [PATCH v5 8/9] iov_iter, block: Make bio structs pin pages rather than ref'ing if appropriate David Howells
2023-01-12 7:44 ` Christoph Hellwig
2023-01-12 10:28 ` David Howells [this message]
2023-01-12 14:09 ` Christoph Hellwig
2023-01-12 14:17 ` Christoph Hellwig
2023-01-12 14:58 ` David Howells
2023-01-12 15:02 ` Christoph Hellwig
2023-01-11 14:28 ` [PATCH v5 9/9] bio: Fix bio_flagged() so that it can be combined David Howells
2023-01-12 7:33 ` Christoph Hellwig
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