From: "Darrick J. Wong" <darrick.wong@oracle.com>
To: Jan Stancek <jstancek@redhat.com>
Cc: naresh.kamboju@linaro.org, hch@infradead.org, ltp@lists.linux.it,
linux-next@vger.kernel.org, linux-fsdevel@vger.kernel.org,
chrubis@suse.cz, linux-kernel@vger.kernel.org,
viro@zeniv.linux.org.uk, broonie@kernel.org, arnd@arndb.de,
lkft-triage@lists.linaro.org, linux-ext4@vger.kernel.org,
tytso@mit.edu
Subject: Re: [PATCH] iomap: fix return value of iomap_dio_bio_actor on 32bit systems
Date: Mon, 11 Nov 2019 17:24:19 -0800 [thread overview]
Message-ID: <20191112012419.GE6211@magnolia> (raw)
In-Reply-To: <b757ff64ddf68519fc3d55b66fcd8a1d4b436395.1573467154.git.jstancek@redhat.com>
On Mon, Nov 11, 2019 at 11:28:10AM +0100, Jan Stancek wrote:
> Naresh reported LTP diotest4 failing for 32bit x86 and arm -next
> kernels on ext4. Same problem exists in 5.4-rc7 on xfs.
>
> The failure comes down to:
> openat(AT_FDCWD, "testdata-4.5918", O_RDWR|O_DIRECT) = 4
> mmap2(NULL, 4096, PROT_READ, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0xb7f7b000
> read(4, 0xb7f7b000, 4096) = 0 // expects -EFAULT
>
> Problem is conversion at iomap_dio_bio_actor() return. Ternary
> operator has a return type and an attempt is made to convert each
> of operands to the type of the other. In this case "ret" (int)
> is converted to type of "copied" (unsigned long). Both have size
> of 4 bytes:
> size_t copied = 0;
> int ret = -14;
> long long actor_ret = copied ? copied : ret;
>
> On x86_64: actor_ret == -14;
> On x86 : actor_ret == 4294967282
>
> Replace ternary operator with 2 return statements to avoid this
> unwanted conversion.
>
> Fixes: 4721a6010990 ("iomap: dio data corruption and spurious errors when pipes fill")
> Reported-by: Naresh Kamboju <naresh.kamboju@linaro.org>
> Signed-off-by: Jan Stancek <jstancek@redhat.com>
Thansk for the full explanation & patch, will test...
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
--D
> ---
> fs/iomap/direct-io.c | 4 +++-
> 1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/fs/iomap/direct-io.c b/fs/iomap/direct-io.c
> index 1fc28c2da279..7c58f51d7da7 100644
> --- a/fs/iomap/direct-io.c
> +++ b/fs/iomap/direct-io.c
> @@ -318,7 +318,9 @@ static void iomap_dio_bio_end_io(struct bio *bio)
> if (pad)
> iomap_dio_zero(dio, iomap, pos, fs_block_size - pad);
> }
> - return copied ? copied : ret;
> + if (copied)
> + return copied;
> + return ret;
> }
>
> static loff_t
> --
> 1.8.3.1
>
next prev parent reply other threads:[~2019-11-12 1:27 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <CA+G9fYtmA5F174nTAtyshr03wkSqMS7+7NTDuJMd_DhJF6a4pw@mail.gmail.com>
[not found] ` <852514139.11036267.1573172443439.JavaMail.zimbra@redhat.com>
2019-11-11 1:26 ` LTP: diotest4.c:476: read to read-only space. returns 0: Success Darrick J. Wong
2019-11-11 8:19 ` Jan Stancek
2019-11-11 8:38 ` Christoph Hellwig
2019-11-11 10:28 ` [PATCH] iomap: fix return value of iomap_dio_bio_actor on 32bit systems Jan Stancek
2019-11-11 10:36 ` Christoph Hellwig
2019-11-12 1:24 ` Darrick J. Wong [this message]
2019-11-11 10:38 ` LTP: diotest4.c:476: read to read-only space. returns 0: Success Jan Stancek
2019-11-11 18:26 ` Naresh Kamboju
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20191112012419.GE6211@magnolia \
--to=darrick.wong@oracle.com \
--cc=arnd@arndb.de \
--cc=broonie@kernel.org \
--cc=chrubis@suse.cz \
--cc=hch@infradead.org \
--cc=jstancek@redhat.com \
--cc=linux-ext4@vger.kernel.org \
--cc=linux-fsdevel@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-next@vger.kernel.org \
--cc=lkft-triage@lists.linaro.org \
--cc=ltp@lists.linux.it \
--cc=naresh.kamboju@linaro.org \
--cc=tytso@mit.edu \
--cc=viro@zeniv.linux.org.uk \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).