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From: Andreas Gruenbacher <agruenba@redhat.com>
To: Al Viro <viro@zeniv.linux.org.uk>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
	Christoph Hellwig <hch@infradead.org>,
	"Darrick J. Wong" <djwong@kernel.org>, Jan Kara <jack@suse.cz>,
	Matthew Wilcox <willy@infradead.org>,
	cluster-devel <cluster-devel@redhat.com>,
	linux-fsdevel <linux-fsdevel@vger.kernel.org>,
	LKML <linux-kernel@vger.kernel.org>,
	ocfs2-devel@oss.oracle.com
Subject: Re: [PATCH v5 03/12] Turn fault_in_pages_{readable,writeable} into fault_in_{readable,writeable}
Date: Tue, 3 Aug 2021 23:38:12 +0200	[thread overview]
Message-ID: <CAHc6FU7iAPOPO7gtDjpSAVyHwgJ7HQPEhDC_2T__DM8GPW5crQ@mail.gmail.com> (raw)
In-Reply-To: <YQmtnuqDwBIBf4N+@zeniv-ca.linux.org.uk>

On Tue, Aug 3, 2021 at 10:57 PM Al Viro <viro@zeniv.linux.org.uk> wrote:
> On Tue, Aug 03, 2021 at 09:18:09PM +0200, Andreas Gruenbacher wrote:
> > Turn fault_in_pages_{readable,writeable} into versions that return the number
> > of bytes faulted in instead of returning a non-zero value when any of the
> > requested pages couldn't be faulted in.  This supports the existing users that
> > require all pages to be faulted in, but also new users that are happy if any
> > pages can be faulted in.
> >
> > Neither of these functions is entirely trivial and it doesn't seem useful to
> > inline them, so move them to mm/gup.c.
> >
> > Rename the functions to fault_in_{readable,writeable} to make sure that code
> > that uses them can be fixed instead of breaking silently.
>
> Sigh...  We'd already discussed that; it's bloody pointless.  Making short
> fault-in return success - absolutely.  Reporting exact number of bytes is
> not going to be of any use to callers.

I'm not actually convinced that you're right about this. Let's see
what we'll end up with; we can always strip things down in the end.

Thanks,
Andreas


  reply	other threads:[~2021-08-03 21:39 UTC|newest]

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-03 19:18 [PATCH v5 00/12] gfs2: Fix mmap + page fault deadlocks Andreas Gruenbacher
2021-08-03 19:18 ` [PATCH v5 01/12] iov_iter: Fix iov_iter_get_pages{,_alloc} page fault return value Andreas Gruenbacher
2021-08-03 19:18 ` [PATCH v5 02/12] powerpc/kvm: Fix kvm_use_magic_page Andreas Gruenbacher
2021-08-03 19:18 ` [PATCH v5 03/12] Turn fault_in_pages_{readable,writeable} into fault_in_{readable,writeable} Andreas Gruenbacher
2021-08-03 19:43   ` Linus Torvalds
2021-08-03 20:57   ` Al Viro
2021-08-03 21:38     ` Andreas Gruenbacher [this message]
2021-08-03 19:18 ` [PATCH v5 04/12] Turn iov_iter_fault_in_readable into fault_in_iov_iter_readable Andreas Gruenbacher
2021-08-03 19:18 ` [PATCH v5 05/12] iov_iter: Introduce fault_in_iov_iter_writeable Andreas Gruenbacher
2021-08-04 15:24   ` Andreas Gruenbacher
2021-08-03 19:18 ` [PATCH v5 06/12] gfs2: Add wrapper for iomap_file_buffered_write Andreas Gruenbacher
2021-08-03 19:18 ` [PATCH v5 07/12] gfs2: Fix mmap + page fault deadlocks for buffered I/O Andreas Gruenbacher
2021-08-03 19:18 ` [PATCH v5 08/12] iomap: Fix iomap_dio_rw return value for user copies Andreas Gruenbacher
2021-08-03 19:18 ` [PATCH v5 09/12] iomap: Support restarting direct I/O requests after user copy failures Andreas Gruenbacher
2021-08-03 19:18 ` [PATCH v5 10/12] iomap: Add done_before argument to iomap_dio_rw Andreas Gruenbacher
2021-08-03 19:18 ` [PATCH v5 11/12] iov_iter: Introduce noio flag to disable page faults Andreas Gruenbacher
2021-08-03 19:18 ` [PATCH v5 12/12] gfs2: Fix mmap + page fault deadlocks for direct I/O Andreas Gruenbacher
2021-08-03 19:45 ` [PATCH v5 00/12] gfs2: Fix mmap + page fault deadlocks Linus Torvalds
2021-08-16 19:14   ` Andreas Gruenbacher
2021-08-18 21:49     ` Linus Torvalds
2021-08-19 19:40       ` Andreas Gruenbacher
2021-08-19 20:14         ` Linus Torvalds
2021-08-19 21:39           ` Andreas Gruenbacher

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