LKML Archive on lore.kernel.org
help / color / mirror / Atom feed
From: Steven Whitehouse <swhiteho@redhat.com>
To: Jan Kara <jack@suse.cz>, Alexey Dobriyan <adobriyan@gmail.com>
Cc: akpm@linux-foundation.org, viro@zeniv.linux.org.uk,
	linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org,
	cluster-devel@redhat.com
Subject: Re: [PATCH] fs: record task name which froze superblock
Date: Wed, 18 Feb 2015 10:18:12 +0000	[thread overview]
Message-ID: <54E466E4.5080704@redhat.com> (raw)
In-Reply-To: <20150218091323.GA4614@quack.suse.cz>

Hi,

On 18/02/15 09:13, Jan Kara wrote:
> On Wed 18-02-15 10:34:55, Alexey Dobriyan wrote:
>> On Mon, Feb 16, 2015 at 10:38:52AM +0100, Jan Kara wrote:
>>> On Sat 14-02-15 21:55:24, Alexey Dobriyan wrote:
>>>> Freezing and thawing are separate system calls, task which is supposed
>>>> to thaw filesystem/superblock can disappear due to crash or not thaw
>>>> due to a bug. Record at least task name (we can't take task_struct
>>>> reference) to make support engineer's life easier.
>>>>
>>>> Hopefully 16 bytes per superblock isn't much.
>>>>
>>>> P.S.: Cc'ing GFS2 people just in case they want to correct
>>>> my understanding of GFS2 having async freeze code.
>>>>
>>>> Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
>>>    Hum, and when do you show the task name? Or do you expect that customer
>>> takes a crashdump and support just finds it in memory?
>> Yeah, having at least something in crashdump is fine.
>    OK, then comment about this at freeze_comm[] definition so that it's
> clear it isn't just set-but-never-read field.
>   
>>>> --- a/fs/ioctl.c
>>>> +++ b/fs/ioctl.c
>>>> @@ -518,6 +518,7 @@ static int ioctl_fioasync(unsigned int fd, struct file *filp,
>>>>   static int ioctl_fsfreeze(struct file *filp)
>>>>   {
>>>>   	struct super_block *sb = file_inode(filp)->i_sb;
>>>> +	int rv;
>>>>   
>>>>   	if (!capable(CAP_SYS_ADMIN))
>>>>   		return -EPERM;
>>>> @@ -527,22 +528,31 @@ static int ioctl_fsfreeze(struct file *filp)
>>>>   		return -EOPNOTSUPP;
>>>>   
>>>>   	/* Freeze */
>>>> -	if (sb->s_op->freeze_super)
>>>> -		return sb->s_op->freeze_super(sb);
>>>> -	return freeze_super(sb);
>>>> +	if (sb->s_op->freeze_super) {
>>>> +		rv = sb->s_op->freeze_super(sb);
>>>> +		if (rv == 0)
>>>> +			get_task_comm(sb->s_writers.freeze_comm, current);
>>>> +	} else
>>>> +		rv = freeze_super(sb);
>>>> +	return rv;
>>>    Why don't you just set the name in ioctl_fsfreeze() in both cases?
>> There are users of freeze_super() in GFS2 unless I'm misreading code.
>    Yes, there are. The call in fs/gfs2/glops.c is in a call path from
> ->freeze_super() handler for GFS2 so that one is handled in
> ioctl_fsfreeze() anyway. The call in fs/gfs2/sys.c is a way to freeze
> filesystem via sysfs (dunno why GFS2 has to invent its own thing and ioctl
> isn't enough). Steven? So having the logic in ioctl_fsfreeze(),
> freeze_bdev() and freeze_store() in gfs2 seems to be enough.
>
The sysfs freeze thing is historical and strongly deprecated - I hope 
that we may be able to remove it one day,

Steve.


  reply	other threads:[~2015-02-18 10:18 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-02-14 18:55 Alexey Dobriyan
2015-02-16  9:38 ` Jan Kara
2015-02-18  7:34   ` Alexey Dobriyan
2015-02-18  7:36     ` [PATCH v2] " Alexey Dobriyan
2015-02-18  9:13     ` [PATCH] " Jan Kara
2015-02-18 10:18       ` Steven Whitehouse [this message]
2015-02-20 11:42       ` Alexey Dobriyan
2015-02-20 12:15         ` Jan Kara
2015-02-28 14:22           ` Alexey Dobriyan
2015-02-28 14:25             ` [PATCH v3] " Alexey Dobriyan
2015-02-28 21:31               ` Dave Chinner
2015-03-02  4:38                 ` Mateusz Guzik
2015-03-02  4:46                   ` Mateusz Guzik
2015-03-09 15:14                     ` Alexey Dobriyan
2015-03-02 21:33                   ` Dave Chinner
2015-03-04 15:14                   ` Alexey Dobriyan

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=54E466E4.5080704@redhat.com \
    --to=swhiteho@redhat.com \
    --cc=adobriyan@gmail.com \
    --cc=akpm@linux-foundation.org \
    --cc=cluster-devel@redhat.com \
    --cc=jack@suse.cz \
    --cc=linux-fsdevel@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=viro@zeniv.linux.org.uk \
    --subject='Re: [PATCH] fs: record task name which froze superblock' \
    /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

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).