From: Dave Chinner <david@fromorbit.com>
To: Jeff Liu <jeff.liu@oracle.com>
Cc: "xfs@oss.sgi.com" <xfs@oss.sgi.com>
Subject: Re: [PATCH] xfs: get new buffer for secondary superblocks from the first new AG
Date: Thu, 21 Mar 2013 16:44:28 +1100 [thread overview]
Message-ID: <20130321054428.GN17758@dastard> (raw)
In-Reply-To: <514A88C3.2030204@oracle.com>
On Thu, Mar 21, 2013 at 12:12:51PM +0800, Jeff Liu wrote:
> In growfs operation, the unused parts of superblocks in the latest old AG are
> zero filled, hence we can safely read the secondary superblock buffer of it
> rather than getting a new buffer for it again.
>From the code:
oagcount = mp->m_sb.sb_agcount;
And because the AG indexes are zero numbered, the index of the
last original AGs is (oagcount - 1). Hence we shoul donly be reading
from the AG headers if the current AG index is less than oagcount.
> This is a small refinement for commits 1375cb65.
>
> Cc: Dave Chinner <david@fromorbit.com>
> Signed-off-by: Jie Liu <jeff.liu@oracle.com>
> ---
> fs/xfs/xfs_fsops.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/fs/xfs/xfs_fsops.c b/fs/xfs/xfs_fsops.c
> index 94eaeed..7d435dd 100644
> --- a/fs/xfs/xfs_fsops.c
> +++ b/fs/xfs/xfs_fsops.c
> @@ -449,7 +449,7 @@ xfs_growfs_data_private(
> * disk as the contents of the new area we are growing into is
> * completely unknown.
> */
> - if (agno < oagcount) {
> + if (agno <= oagcount) {
With this change, when agno == oagcount we are one AG beyond the
original filesystem size and so if we read that space, we are
reading uninitialised data.
AFAICT, the current code is correct...
Cheers,
Dave.
--
Dave Chinner
david@fromorbit.com
_______________________________________________
xfs mailing list
xfs@oss.sgi.com
http://oss.sgi.com/mailman/listinfo/xfs
next prev parent reply other threads:[~2013-03-21 5:44 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-03-21 4:12 [PATCH] xfs: get new buffer for secondary superblocks from the first new AG Jeff Liu
2013-03-21 5:44 ` Dave Chinner [this message]
2013-03-21 6:27 ` Jeff Liu
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=20130321054428.GN17758@dastard \
--to=david@fromorbit.com \
--cc=jeff.liu@oracle.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