From: Brian Foster <bfoster@redhat.com>
To: Dave Chinner <david@fromorbit.com>
Cc: xfs@oss.sgi.com
Subject: Re: [RFC PATCH 2/4] xfs: create function to scan and clear EOFBLOCKS inodes
Date: Wed, 05 Sep 2012 08:22:00 -0400 [thread overview]
Message-ID: <504743E8.7040500@redhat.com> (raw)
In-Reply-To: <20120905064202.GG15292@dastard>
On 09/05/2012 02:42 AM, Dave Chinner wrote:
> On Tue, Sep 04, 2012 at 10:10:00AM -0400, Brian Foster wrote:
>> On 09/03/2012 01:06 AM, Dave Chinner wrote:
>>> On Mon, Aug 27, 2012 at 03:51:49PM -0400, Brian Foster wrote:
>> ...
>>>> +/*
>>>> + * Handle an EOFBLOCKS tagged inode. If this is a forced scan, we wait on the
>>>> + * iolock ourselves rather than rely on the trylock in xfs_free_eofblocks().
>>>> + *
>>>> + * We rely on the output parameter from xfs_free_eofblocks() to determine
>>>> + * whether we should clear the tag because in the trylock case, it could have
>>>> + * skipped the inode due to lock contention.
>>>> + */
>>>> +STATIC int
>>>> +xfs_inode_free_eofblocks(
>>>> + struct xfs_inode *ip,
>>>> + int flags)
>>>> +{
>>>> + int ret = 0;
>>>> + bool freed = false;
>>>> + bool wait_iolock = (flags & EOFBLOCKS_WAIT) ? true : false;
>>>> +
>>>> + if (wait_iolock)
>>>> + xfs_ilock(ip, XFS_IOLOCK_EXCL);
>>>
>>> Why do we need the IO lock here? xfs_free_eofblocks() does all the
>>> necessary locking....
>>>
>>
>> This was for the wait case (e.g., xfs_free_eofblocks() does a trylock
>> on the IO lock and we want to wait for the lock in this case).
>
> Does it really matter if we can't get the iolock and skip the inode?
>
Well I thought that was the point of the force/wait scan as opposed to
the best effort scan. But...
> Note that xfs_inode_ag_walk() will keep a skipped count if you
> return EAGAIN, and re-run the walk on the AG if any inodes are
> skipped. This is done to prevent blocking on locks slowing down the
> scan - instead of blocking we move on to the next inode, and revist
> the blocked inodes again in a later pass.
>
> IOWs, if you convert the code to use the generic walk and make
> xfs_free_eofblocks() return EAGAIN when it can't get the io lock,
> you get the retry for free...
>
This sounds more efficient. ;) I'll move it to this approach. Thanks.
Brian
> Cheers,
>
> Dave.
>
_______________________________________________
xfs mailing list
xfs@oss.sgi.com
http://oss.sgi.com/mailman/listinfo/xfs
next prev parent reply other threads:[~2012-09-05 12:22 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-08-27 19:51 [RFC PATCH 0/4] xfs: add support for tracking inodes with post-EOF speculative preallocation Brian Foster
2012-08-27 19:51 ` [RFC PATCH 1/4] xfs: add EOFBLOCKS inode tagging/untagging Brian Foster
2012-09-03 4:20 ` Dave Chinner
2012-08-27 19:51 ` [RFC PATCH 2/4] xfs: create function to scan and clear EOFBLOCKS inodes Brian Foster
2012-09-03 5:06 ` Dave Chinner
2012-09-04 14:10 ` Brian Foster
2012-09-05 6:42 ` Dave Chinner
2012-09-05 12:22 ` Brian Foster [this message]
2012-08-27 19:51 ` [RFC PATCH 3/4] xfs: add FREE_EOFBLOCKS ioctl Brian Foster
2012-09-03 5:17 ` Dave Chinner
2012-09-04 14:10 ` Brian Foster
2012-09-05 6:49 ` Dave Chinner
2012-09-05 12:22 ` Brian Foster
2012-08-27 19:51 ` [RFC PATCH 4/4] xfs: add background scanning to clear EOFBLOCKS inodes Brian Foster
2012-09-03 5:28 ` Dave Chinner
2012-09-04 14:10 ` Brian Foster
2012-09-05 7:00 ` Dave Chinner
2012-09-05 12:22 ` Brian Foster
2012-09-05 23:43 ` Dave Chinner
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=504743E8.7040500@redhat.com \
--to=bfoster@redhat.com \
--cc=david@fromorbit.com \
--cc=xfs@oss.sgi.com \
/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