From: Dave Chinner <david@fromorbit.com>
To: Eric Sandeen <sandeen@redhat.com>
Cc: xfs@oss.sgi.com
Subject: Re: [PATCH 1/9] xfs: skip verification on initial "guess" superblock read
Date: Wed, 19 Feb 2014 14:36:31 +1100 [thread overview]
Message-ID: <20140219033631.GK13647@dastard> (raw)
In-Reply-To: <1392767549-25574-2-git-send-email-sandeen@redhat.com>
On Tue, Feb 18, 2014 at 05:52:21PM -0600, Eric Sandeen wrote:
> When xfs_readsb() does the very first read of the superblock,
> it makes a guess at the length of the buffer, based on the
> sector size of the underlying storage. This may or may
> not match the filesystem sector size in sb_sectsize, so
> we can't i.e. do a CRC check on it; it might be too short.
>
> In fact, mounting a filesystem with sb_sectsize larger
> than the device sector size will cause a mount failure
> if CRCs are enabled, because we are checksumming a length
> which exceeds the buffer passed to it.
>
> So always read twice; the first time we read with NULL
> buffer ops to skip verification; then set the proper
> read length, hook up the proper verifier, and give it
> another go.
>
> Once we are sure that we've got the right buffer length,
> we can also use bp->b_length in the xfs_sb_read_verify,
> rather than the less-trusted on-disk sectorsize for
> secondary superblocks. Before this we ran the risk of
> passing junk to the crc32c routines, which didn't always
> handle extreme values.
>
> Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Looks good.
Reviewed-by: Dave Chinner <dchinner@redhat.com>
--
Dave Chinner
david@fromorbit.com
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next prev parent reply other threads:[~2014-02-19 3:37 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-02-18 23:52 [PATCH 0/9] current series for verifier error differentiation Eric Sandeen
2014-02-18 23:52 ` [PATCH 1/9] xfs: skip verification on initial "guess" superblock read Eric Sandeen
2014-02-19 3:36 ` Dave Chinner [this message]
2014-02-18 23:52 ` [PATCH 2/9] xfs: limit superblock corruption errors to actual corruption Eric Sandeen
2014-02-19 3:37 ` Dave Chinner
2014-02-18 23:52 ` [PATCH 3/9] xfs: skip pointless CRC updates after verifier failures Eric Sandeen
2014-02-19 6:35 ` Jeff Liu
2014-02-18 23:52 ` [PATCH 4/9] xfs: Use defines for CRC offsets in all cases Eric Sandeen
2014-02-19 7:56 ` Jeff Liu
2014-02-20 0:27 ` Dave Chinner
2014-02-20 9:33 ` Jeff Liu
2014-02-20 9:41 ` Jeff Liu
2014-02-27 2:15 ` Dave Chinner
2014-02-18 23:52 ` [PATCH 5/9] xfs: add helper for verifying checksums on xfs_bufs Eric Sandeen
2014-02-27 4:17 ` Dave Chinner
2014-02-18 23:52 ` [PATCH 6/9] xfs: add helper for updating " Eric Sandeen
2014-02-18 23:52 ` [PATCH 7/9] xfs: add xfs_verifier_error() Eric Sandeen
2014-02-19 6:30 ` Dave Chinner
2014-02-20 2:58 ` [PATCH 7/9 V2] " Eric Sandeen
2014-02-27 4:20 ` Dave Chinner
2014-02-18 23:52 ` [PATCH 8/9] xfs: print useful caller information in xfs_error_report Eric Sandeen
2014-02-19 12:42 ` Jeff Liu
2014-02-18 23:52 ` [PATCH 9/9] xfs: modify verifiers to differentiate CRC from other errors Eric Sandeen
2014-02-19 14:01 ` Brian Foster
2014-02-19 16:12 ` Eric Sandeen
2014-02-20 3:10 ` [PATCH 9/9 V2] " Eric Sandeen
2014-02-20 13:10 ` Brian Foster
2014-02-27 9:12 ` [PATCH 0/9] current series for verifier error differentiation Dave Chinner
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