From: David Laight <David.Laight@ACULAB.COM>
To: 'Mikulas Patocka' <mpatocka@redhat.com>
Cc: 'Al Viro' <viro@zeniv.linux.org.uk>,
Andrew Morton <akpm@linux-foundation.org>,
Dan Williams <dan.j.williams@intel.com>,
"Vishal Verma" <vishal.l.verma@intel.com>,
Dave Jiang <dave.jiang@intel.com>,
"Ira Weiny" <ira.weiny@intel.com>,
Matthew Wilcox <willy@infradead.org>, Jan Kara <jack@suse.cz>,
Steven Whitehouse <swhiteho@redhat.com>,
Eric Sandeen <esandeen@redhat.com>,
Dave Chinner <dchinner@redhat.com>, Theodore Ts'o <tytso@mit.edu>,
Wang Jianchao <jianchao.wan9@gmail.com>,
"Kani, Toshi" <toshi.kani@hpe.com>,
"Norton, Scott J" <scott.norton@hpe.com>,
"Tadakamadla, Rajesh" <rajesh.tadakamadla@hpe.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>,
"linux-nvdimm@lists.01.org" <linux-nvdimm@lists.01.org>
Subject: RE: [RFC v2] nvfs: a filesystem for persistent memory
Date: Mon, 11 Jan 2021 11:57:08 +0000 [thread overview]
Message-ID: <57dad96341d34822a7943242c9bcad71@AcuMS.aculab.com> (raw)
In-Reply-To: <alpine.LRH.2.02.2101110641490.4356@file01.intranet.prod.int.rdu2.redhat.com>
From: Mikulas Patocka
> Sent: 11 January 2021 11:44
> On Mon, 11 Jan 2021, David Laight wrote:
>
> > From: Al Viro <viro@ftp.linux.org.uk> On Behalf Of Al Viro
> > > Sent: 10 January 2021 16:20
...
...
> > > while (iov_iter_count(to)) {
...
> > > size = copy_to_iter(to, ptr, size);
> > > if (unlikely(!size)) {
> > > r = -EFAULT;
> > > goto ret_r;
> > > }
> > >
> > > pos += size;
> > > total += size;
> > > } while (iov_iter_count(to));
> >
> > That isn't the best formed loop!
> >
> > David
>
> I removed the second "while" statement and fixed the arguments to
> copy_to_iter - other than that, Al's function works.
The extra while is easy to write and can be difficult to spot.
I've found them looking as the object code before now!
Oh - the error return for copy_to_iter() is wrong.
It should (probably) return 'total' if it is nonzero.
David
-
Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
Registration No: 1397386 (Wales)
next prev parent reply other threads:[~2021-01-11 11:59 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-07 13:15 [RFC v2] nvfs: a filesystem for persistent memory Mikulas Patocka
2021-01-07 15:11 ` Expense of read_iter Matthew Wilcox
2021-01-07 16:43 ` Mingkai Dong
2021-01-12 13:45 ` Zhongwei Cai
2021-01-12 14:06 ` David Laight
2021-01-13 16:44 ` Mikulas Patocka
2021-01-15 9:40 ` Zhongwei Cai
2021-01-20 4:47 ` Dave Chinner
2021-01-20 14:18 ` Jan Kara
2021-01-20 15:12 ` Mikulas Patocka
2021-01-20 15:44 ` David Laight
2021-01-21 15:47 ` Matthew Wilcox
2021-01-21 16:06 ` Mikulas Patocka
2021-01-21 16:30 ` Zhongwei Cai
2021-01-07 18:59 ` Mikulas Patocka
2021-01-10 6:13 ` Matthew Wilcox
2021-01-10 21:19 ` Mikulas Patocka
2021-01-11 0:18 ` Matthew Wilcox
2021-01-11 21:10 ` Mikulas Patocka
2021-01-11 10:11 ` David Laight
2021-01-10 16:20 ` [RFC v2] nvfs: a filesystem for persistent memory Al Viro
2021-01-10 16:51 ` Al Viro
2021-01-10 21:14 ` Mikulas Patocka
2021-01-10 23:40 ` Al Viro
2021-01-11 11:41 ` Mikulas Patocka
2021-01-11 10:29 ` David Laight
2021-01-11 11:44 ` Mikulas Patocka
2021-01-11 11:57 ` David Laight [this message]
2021-01-11 14:43 ` Al Viro
2021-01-11 14:54 ` David Laight
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