From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: Konstantin Khlebnikov <koct9i@gmail.com>
Cc: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
NeilBrown <neilb@suse.de>, Tejun Heo <tj@kernel.org>,
Stable <stable@vger.kernel.org>,
Alexander Viro <viro@zeniv.linux.org.uk>
Subject: Re: [PATCH] sysfs: correctly handle read offset on PREALLOC attrs
Date: Mon, 5 Sep 2016 15:46:28 +0200 [thread overview]
Message-ID: <20160905134628.GA30206@kroah.com> (raw)
In-Reply-To: <CALYGNiNGnfGpQkGsmn7JN5p-TQCkY2imU1arrUfukDNxgSeOTw@mail.gmail.com>
On Mon, Sep 05, 2016 at 04:25:48PM +0300, Konstantin Khlebnikov wrote:
> Bump
Huh?
> On Wed, Jun 22, 2016 at 9:42 PM, Konstantin Khlebnikov
> <khlebnikov@yandex-team.ru> wrote:
> > Attributes declared with __ATTR_PREALLOC use sysfs_kf_read() which returns
> > zero bytes for non-zero offset. This breaks script checkarray in mdadm tool
> > in debian where /bin/sh is 'dash' because its builtin 'read' reads only one
> > byte at a time. Script gets 'i' instead of 'idle' when reads current action
> > from /sys/block/$dev/md/sync_action and as a result does nothing.
> >
> > This patch adds trivial implementation of partial read: generate whole
> > string and move required part into buffer head.
> >
> > Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
> > Fixes: 4ef67a8c95f3 ("sysfs/kernfs: make read requests on pre-alloc files use the buffer.")
> > Link: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=787950
> > Cc: Stable <stable@vger.kernel.org> # v3.19+
> > ---
> > fs/sysfs/file.c | 8 +++++++-
> > 1 file changed, 7 insertions(+), 1 deletion(-)
> >
> > diff --git a/fs/sysfs/file.c b/fs/sysfs/file.c
> > index f35523d4fa3a..b803213d1307 100644
> > --- a/fs/sysfs/file.c
> > +++ b/fs/sysfs/file.c
> > @@ -114,9 +114,15 @@ static ssize_t sysfs_kf_read(struct kernfs_open_file *of, char *buf,
> > * If buf != of->prealloc_buf, we don't know how
> > * large it is, so cannot safely pass it to ->show
> > */
> > - if (pos || WARN_ON_ONCE(buf != of->prealloc_buf))
> > + if (WARN_ON_ONCE(buf != of->prealloc_buf))
> > return 0;
> > len = ops->show(kobj, of->kn->priv, buf);
> > + if (pos) {
> > + if (len <= pos)
> > + return 0;
> > + len -= pos;
> > + memmove(buf, buf + pos, len);
> > + }
> > return min(count, len);
> > }
I don't have this in any queue of mine, so I don't understand what you
are asking about.
totally confused,
greg k-h
next prev parent reply other threads:[~2016-09-05 13:46 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-06-22 18:42 [PATCH] sysfs: correctly handle read offset on PREALLOC attrs Konstantin Khlebnikov
2016-06-23 21:18 ` Tejun Heo
2016-09-05 13:25 ` Konstantin Khlebnikov
2016-09-05 13:46 ` Greg Kroah-Hartman [this message]
2016-09-05 14:02 ` Konstantin Khlebnikov
2016-09-05 14:15 ` Greg Kroah-Hartman
2016-09-05 14:13 ` Greg Kroah-Hartman
2016-09-05 14:17 ` Konstantin Khlebnikov
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=20160905134628.GA30206@kroah.com \
--to=gregkh@linuxfoundation.org \
--cc=khlebnikov@yandex-team.ru \
--cc=koct9i@gmail.com \
--cc=linux-kernel@vger.kernel.org \
--cc=neilb@suse.de \
--cc=stable@vger.kernel.org \
--cc=tj@kernel.org \
--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).