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Re: [PATCH] Re: XFS: Assertion failed: first <= last && last < BBTOB(bp-

To: Brian Foster <bfoster@xxxxxxxxxx>
Subject: Re: [PATCH] Re: XFS: Assertion failed: first <= last && last < BBTOB(bp->b_length), file: fs/xfs/xfs_trans_buf.c, line: 568
From: Mark Tinguely <tinguely@xxxxxxx>
Date: Mon, 26 Aug 2013 10:00:24 -0500
Cc: Dave Chinner <david@xxxxxxxxxxxxx>, xfs@xxxxxxxxxxx
Delivered-to: xfs@xxxxxxxxxxx
In-reply-to: <521B59C7.1080803@xxxxxxxxxx>
References: <52165830.8050006@xxxxxxxxxx> <20130826041330.GU6023@dastard> <521B59C7.1080803@xxxxxxxxxx>
User-agent: Mozilla/5.0 (X11; FreeBSD amd64; rv:9.0) Gecko/20120122 Thunderbird/9.0
On 08/26/13 08:36, Brian Foster wrote:
On 08/26/2013 12:13 AM, Dave Chinner wrote:
On Thu, Aug 22, 2013 at 02:28:00PM -0400, Brian Foster wrote:
Hi all,

I hit an assert on a debug kernel while beating on some finobt work and
eventually reproduced it on unmodified/TOT xfs/xfsprogs as of today. I
hit it through a couple different paths, first while running fsstress on
a CRC enabled filesystem (with otherwise default mkfs options):

(These tests are running on a 4p, 4GB VM against a 100GB virtio disk,
hosted on a single spindle desktop box).

crc=1
fsstress -z -fsymlink=1 -n99999999 -p4 -d /mnt/test

XFS: Assertion failed: first<= last&&  last<  BBTOB(bp->b_length),

Directory buffer overrun.

  [<ffffffffa031d549>] xfs_trans_log_buf+0x89/0x1b0 [xfs]
  [<ffffffffa02e7c1c>] xfs_da3_node_add+0x11c/0x210 [xfs]
  [<ffffffffa02ea703>] xfs_da3_node_split+0xc3/0x230 [xfs]
  [<ffffffffa02eaa18>] xfs_da3_split+0x1a8/0x410 [xfs]
  [<ffffffffa02f743f>] xfs_dir2_node_addname+0x47f/0xde0 [xfs]

During a split.

Easily reproduced with "seq 200000 | xargs touch" as Michael Semon
reported last week.

The fix demonstrates my concerns about modifying directory code -
the CRC changes missed a *fundamental* directory format definition,
and we've only just tripped over it....

I agree. As we see here, bugs in common directory code effect all filesystems. It may not matter if the feature the code was written for is enabled or not.

rm -rf /mnt/test

XFS: Assertion failed: first<= last&&  last<  BBTOB(bp->b_length),

Directory buffer overrun.

  [<ffffffffa032b549>] xfs_trans_log_buf+0x89/0x1b0 [xfs]
  [<ffffffffa02f61ff>] xfs_da3_node_unbalance+0xef/0x1d0 [xfs]
  [<ffffffffa02f98b0>] xfs_da3_join+0x240/0x290 [xfs]
  [<ffffffffa030659b>] xfs_dir2_node_removename+0x69b/0x8b0 [xfs]

During a merge. Not sure why that is happening on a v4 filesystem.
V5 filesystem, yes, due to the above bug but v4 should not be
affected.


Interesting, thanks Dave. FWIW, I no longer reproduce the assert in
either scenario with this patch applied. I also don't see how it would
make a difference for a v4 superblock filesystem. Perhaps that
particular test was bogus. I haven't heard if Mark happened to reproduce
that one. Regardless, consider it:

Tested-by: Brian Foster<bfoster@xxxxxxxxxx>

(xfs: fix calculation of the number of node entries in a dir3 node)

I got the XFS v4 to assert on the remove in Linux 3.10 and 3.11.

With the patch, a shorter test on Linux 3.10 did not assert. I will do the full test on Linux 3.10/3.11, review and report back.


Brian

Cheers,

Dave.

--Mark.

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