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From: Eric Sandeen <sandeen@redhat.com>
To: "Theodore Ts'o" <tytso@mit.edu>
Cc: Ext4 Developers List <linux-ext4@vger.kernel.org>, forrestl@synology.com
Subject: Re: [PATCH 1/3] e2fsck: fix incorrect interior node logical start values
Date: Fri, 21 Dec 2012 14:47:58 -0600	[thread overview]
Message-ID: <50D4CAFE.5010606@redhat.com> (raw)
In-Reply-To: <1356047023-28367-1-git-send-email-tytso@mit.edu>

On 12/20/12 5:43 PM, Theodore Ts'o wrote:
> From: Eric Sandeen <sandeen@redhat.com>
> 
> An index node's logical start (ei_block) should
> match the logical start of the first node (index
> or leaf) below it.  If we find a node whose start
> does not match its parent, fix all of its parents
> accordingly.
> 
> If it finds such a problem, we'll see:
> 
> Pass 1: Checking inodes, blocks, and sizes
> Interior extent node level 0 of inode 274258:
> Logical start 3666 does not match logical start 4093 at next level.  Fix<y>?

Hm, this situation might still need more work in some cases.

Looking at a "bad" extent tree reported to me:

 1/ 2  25/ 29 57524 - 59011 15538183              1488
 2/ 2   1/  2 57524 - 59011 15556788 - 15558275   1488
 2/ 2   2/  2 59012 - 65535 15558276 - 15564799   6524 Uninit <- what's this extent?

 1/ 2  26/ 29 59012 - 60671 15538184              1660
 2/ 2   1/  2 59012 - 60671    25638 -    27297   1660
 2/ 2   2/  2 60672 - 60689    27298 -    27315     18 Uninit

 1/ 2  27/ 29 60672 - 61023 15538185               352 <- bad logical start
 2/ 2   1/ 19 60690 - 60690    27316 -    27316      1 Uninit


e2fsck with my patch finds & fixes the parent issues:

Pass 1: Checking inodes, blocks, and sizes
Interior extent node level 1 of inode 8126473:
Logical start 60672 does not match logical start 60690 at next level.  Fix? yes

Interior extent node level 1 of inode 8126473:
Logical start 63157 does not match logical start 63159 at next level.  Fix? yes

and after that the extents look like:

 1/ 2  25/ 29 57524 - 59011 15538183              1488
 2/ 2   1/  2 57524 - 59011 15556788 - 15558275   1488
 2/ 2   2/  2 59012 - 65535 15558276 - 15564799   6524 Uninit <--- ???

 1/ 2  26/ 29 59012 - 60689 15538184              1678
 2/ 2   1/  2 59012 - 60671    25638 -    27297   1660
 2/ 2   2/  2 60672 - 60689    27298 -    27315     18 Uninit

 1/ 2  27/ 29 60690 - 61023 15538185               334 <-- only this got fixed
 2/ 2   1/ 19 60690 - 60690    27316 -    27316      1 Uninit

but in this case, it seems that the length of the range covered by the previous interior nodes is still incorrect.  :(

-Eric

  parent reply	other threads:[~2012-12-21 20:48 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-12-13 15:32 [PATCH] ext4: fix extent tree corruption that incurred by hole punch [V2] Forrest Liu
2012-12-13 16:04 ` Forrest Liu
2012-12-13 16:17   ` Forrest Liu
2012-12-14 17:18   ` Eric Sandeen
2012-12-17  4:25 ` Ashish Sangwan
2012-12-20  5:39 ` Theodore Ts'o
2012-12-20 15:11   ` Forrest Liu
2012-12-20 23:42     ` Theodore Ts'o
2012-12-20 23:43       ` [PATCH 1/3] e2fsck: fix incorrect interior node logical start values Theodore Ts'o
2012-12-20 23:43         ` [PATCH 2/3] libext2fs: ext2fs_extents_fix_parents() should not modify the handle location Theodore Ts'o
2012-12-20 23:43         ` [PATCH 3/3] e2fsck: make sure the extent tree is consistent after bogus node in the tree Theodore Ts'o
2012-12-21  3:19           ` Theodore Ts'o
2012-12-21 11:02             ` Forrest Liu
2012-12-21 15:34           ` Eric Sandeen
2012-12-21 20:47         ` Eric Sandeen [this message]
2012-12-24 14:57           ` [PATCH 1/3] e2fsck: fix incorrect interior node logical start values Theodore Ts'o

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