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From: Dave Chinner <david@fromorbit.com>
To: "Darrick J. Wong" <darrick.wong@oracle.com>
Cc: linux-xfs@vger.kernel.org
Subject: Re: [PATCH 11/25] xfs: scrub the AGI
Date: Thu, 5 Oct 2017 09:16:34 +1100	[thread overview]
Message-ID: <20171004221634.GG3666@dastard> (raw)
In-Reply-To: <20171004180204.GU6503@magnolia>

On Wed, Oct 04, 2017 at 11:02:04AM -0700, Darrick J. Wong wrote:
> On Wed, Oct 04, 2017 at 05:43:33PM +1100, Dave Chinner wrote:
> > It seems to me that we're using the superblock 0 values as the
> > golden master because it's a mounted filesystem, and then comparing
> > everything else against it. Maybe we should at least check a couple
> > of secondary superblocks to see that they match the primary
> > superblock - that way we'll have some confidence that at least
> > things like agcount, agblocks, dblocks, etc are valid before we go
> > any further...
> 
> xfs_scrub_superblock does check the secondary superblock geometry
> against whatever's in mp->m_sb, which came from sb 0.

/me smacks forehead

The patch is even named "scrub the backup superblocks".

Perhaps it didn't sink in because they are normally called
"secondary superblocks". My bad....

> > BUt maybe all we need is comment in the overall scrub description -
> > that we're pretty much assuming that sb 0 is intact because we write
> > what is in memory back to it and so we can simply validate
> > everything else against the primary superblock contents...
> 
> Correct.  Since scrub is run against a mounted live filesystem we assume
> that the mount code fully validated sb 0 and therefore we can rely on it
> not being wrong.
> 
> If OTOH sb 0 *is* wrong then the admin is better off running xfs_repair
> because there's too much whirring machinery to go changing fundamental
> geometry.

Yup, that makes sense.

Cheers,

Dave.
-- 
Dave Chinner
david@fromorbit.com

  reply	other threads:[~2017-10-04 22:18 UTC|newest]

Thread overview: 91+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-10-03 20:40 [PATCH v11 00/25] xfs: online scrub support Darrick J. Wong
2017-10-03 20:40 ` [PATCH 01/25] xfs: create an ioctl to scrub AG metadata Darrick J. Wong
2017-10-03 20:41 ` [PATCH 02/25] xfs: dispatch metadata scrub subcommands Darrick J. Wong
2017-10-03 20:41 ` [PATCH 03/25] xfs: probe the scrub ioctl Darrick J. Wong
2017-10-03 23:32   ` Dave Chinner
2017-10-04  0:02     ` Darrick J. Wong
2017-10-04  1:56       ` Dave Chinner
2017-10-04  3:14         ` Darrick J. Wong
2017-10-03 20:41 ` [PATCH 04/25] xfs: create helpers to record and deal with scrub problems Darrick J. Wong
2017-10-03 23:44   ` Dave Chinner
2017-10-04  0:56     ` Darrick J. Wong
2017-10-03 20:41 ` [PATCH 05/25] xfs: create helpers to scrub a metadata btree Darrick J. Wong
2017-10-03 23:49   ` Dave Chinner
2017-10-04  0:13     ` Darrick J. Wong
2017-10-03 20:41 ` [PATCH 06/25] xfs: scrub the shape of " Darrick J. Wong
2017-10-04  0:15   ` Dave Chinner
2017-10-04  3:51     ` Darrick J. Wong
2017-10-04  5:48       ` Dave Chinner
2017-10-04 17:48         ` Darrick J. Wong
2017-10-03 20:41 ` [PATCH 07/25] xfs: scrub btree keys and records Darrick J. Wong
2017-10-04 20:52   ` Darrick J. Wong
2017-10-03 20:41 ` [PATCH 08/25] xfs: create helpers to scan an allocation group Darrick J. Wong
2017-10-04  0:46   ` Dave Chinner
2017-10-04  3:58     ` Darrick J. Wong
2017-10-04  5:59       ` Dave Chinner
2017-10-04 17:51         ` Darrick J. Wong
2017-10-03 20:41 ` [PATCH 09/25] xfs: scrub the backup superblocks Darrick J. Wong
2017-10-04  0:57   ` Dave Chinner
2017-10-04  4:06     ` Darrick J. Wong
2017-10-04  6:13       ` Dave Chinner
2017-10-04 17:56         ` Darrick J. Wong
2017-10-03 20:41 ` [PATCH 10/25] xfs: scrub AGF and AGFL Darrick J. Wong
2017-10-04  1:31   ` Dave Chinner
2017-10-04  4:21     ` Darrick J. Wong
2017-10-04  6:28       ` Dave Chinner
2017-10-04 17:57         ` Darrick J. Wong
2017-10-03 20:41 ` [PATCH 11/25] xfs: scrub the AGI Darrick J. Wong
2017-10-04  1:43   ` Dave Chinner
2017-10-04  4:25     ` Darrick J. Wong
2017-10-04  6:43       ` Dave Chinner
2017-10-04 18:02         ` Darrick J. Wong
2017-10-04 22:16           ` Dave Chinner [this message]
2017-10-04 23:12             ` Darrick J. Wong
2017-10-03 20:42 ` [PATCH 12/25] xfs: scrub free space btrees Darrick J. Wong
2017-10-05  0:59   ` Dave Chinner
2017-10-05  1:13     ` Darrick J. Wong
2017-10-03 20:42 ` [PATCH 13/25] xfs: scrub inode btrees Darrick J. Wong
2017-10-05  2:08   ` Dave Chinner
2017-10-05  5:47     ` Darrick J. Wong
2017-10-05  7:22       ` Dave Chinner
2017-10-05 18:26         ` Darrick J. Wong
2017-10-03 20:42 ` [PATCH 14/25] xfs: scrub rmap btrees Darrick J. Wong
2017-10-05  2:56   ` Dave Chinner
2017-10-05  5:02     ` Darrick J. Wong
2017-10-03 20:42 ` [PATCH 15/25] xfs: scrub refcount btrees Darrick J. Wong
2017-10-05  2:59   ` Dave Chinner
2017-10-05  5:02     ` Darrick J. Wong
2017-10-03 20:42 ` [PATCH 16/25] xfs: scrub inodes Darrick J. Wong
2017-10-05  4:04   ` Dave Chinner
2017-10-05  5:22     ` Darrick J. Wong
2017-10-05  7:13       ` Dave Chinner
2017-10-05 19:56         ` Darrick J. Wong
2017-10-03 20:42 ` [PATCH 17/25] xfs: scrub inode block mappings Darrick J. Wong
2017-10-06  2:51   ` Dave Chinner
2017-10-06 17:00     ` Darrick J. Wong
2017-10-07 23:10       ` Dave Chinner
2017-10-08  3:54         ` Darrick J. Wong
2017-10-03 20:42 ` [PATCH 18/25] xfs: scrub directory/attribute btrees Darrick J. Wong
2017-10-06  5:07   ` Dave Chinner
2017-10-06 18:30     ` Darrick J. Wong
2017-10-03 20:42 ` [PATCH 19/25] xfs: scrub directory metadata Darrick J. Wong
2017-10-06  7:07   ` Dave Chinner
2017-10-06 19:45     ` Darrick J. Wong
2017-10-06 22:16       ` Dave Chinner
2017-10-03 20:42 ` [PATCH 20/25] xfs: scrub directory freespace Darrick J. Wong
2017-10-09  1:44   ` Dave Chinner
2017-10-09 22:54     ` Darrick J. Wong
2017-10-03 20:43 ` [PATCH 21/25] xfs: scrub extended attributes Darrick J. Wong
2017-10-09  2:13   ` Dave Chinner
2017-10-09 21:14     ` Darrick J. Wong
2017-10-03 20:43 ` [PATCH 22/25] xfs: scrub symbolic links Darrick J. Wong
2017-10-09  2:17   ` Dave Chinner
2017-10-03 20:43 ` [PATCH 23/25] xfs: scrub parent pointers Darrick J. Wong
2017-10-03 20:43 ` [PATCH 24/25] xfs: scrub realtime bitmap/summary Darrick J. Wong
2017-10-09  2:28   ` Dave Chinner
2017-10-09 20:24     ` Darrick J. Wong
2017-10-03 20:43 ` [PATCH 25/25] xfs: scrub quota information Darrick J. Wong
2017-10-09  2:51   ` Dave Chinner
2017-10-09 20:03     ` Darrick J. Wong
2017-10-09 22:17       ` Dave Chinner
2017-10-09 23:08         ` Darrick J. Wong

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