Bug 679566

Summary: gfs2_edit savemeta doesn't save all leaf blocks for large dirs
Product: Red Hat Enterprise Linux 6 Reporter: Robert Peterson <rpeterso>
Component: clusterAssignee: Robert Peterson <rpeterso>
Status: CLOSED ERRATA QA Contact: Cluster QE <mspqa-list>
Severity: low Docs Contact:
Priority: medium    
Version: 6.1CC: ccaulfie, cluster-maint, djansa, edamato, fdinitto, lhh, mjuricek, rpeterso, teigland
Target Milestone: rc   
Target Release: ---   
Hardware: Unspecified   
OS: Unspecified   
Whiteboard:
Fixed In Version: cluster-3.0.12.1-2.el6 Doc Type: Bug Fix
Doc Text:
Cause A user performs the command "gfs2_edit savemeta" to save off the metadata for a target GFS2 file system. However, not all of the directory information is saved for large directories. If the metadata is restored to another device, fsck.gfs2 will find directory corruption due to missing leaf blocks. Consequence The bug was caused because gfs2_edit was treating the directory leaf index (known as the directory hash table) like it did a normal data file. In other words, a collection of metadata blocks. For a normal data file gfs2_edit needs to save only the metadata blocks, but not the user's data blocks. For a directory, gfs2_edit needs to save the "data" because the "data" blocks are the actual directory hash table, and the blocks beneath it are the directory leaf blocks that also need to be saved. Fix The fix was to change gfs2_edit's savemeta function to actually read all the data (i.e. the directory hash table) for large directories and traverse the hash table, saving all the leaf blocks. Result With the directory hash table processed properly, all leaf blocks are saved properly.
 Story Points: ---
Clone Of: 679565 Environment:
Last Closed: 2011-12-06 14:50:54 UTC Type: ---
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Embargoed:
Bug Depends On: 679565    
Bug Blocks:    
Attachments:
Description Flags
RHEL6 patch none

Description Robert Peterson 2011-02-22 21:23:19 UTC 
+++ This bug was initially created as a clone of Bug #679565 +++
Crosswrite to RHEL6

Description of problem:
If you have a large enough directory, gfs2_edit savemeta
won't save all of its leaf blocks.

Version-Release number of selected component (if applicable):
RHEL56

How reproducible:
Always

Steps to Reproduce:
1. mkfs.gfs2 -O -t bobs_roth:roth_lv -p lock_dlm -j 4 /dev/roth_vg/roth_lv
2. mount -tgfs2 /dev/roth_vg/roth_lv /mnt/gfs2
3. mkdir /mnt/gfs2/bigdir
4. for i in `seq 1 543562` ; do dd if=/dev/zero of=/mnt/gfs2/bigdir/gfs2.$i bs=4K count=3 &>/dev/null; done
5. umount /mnt/gfs2
6. gfs2_edit savemeta /dev/roth_vg/roth_lv halfamillion12Kfiles.meta
7. gfs2_edit printsavedmeta halfamillion12Kfiles.meta > /tmp/gronk
8. grep "directory leaf" /tmp/gronk | wc -l
  
Actual results:
0

Expected results:
10214


Additional info:
Patch in hand

--- Additional comment from rpeterso on 2011-02-22 16:22:25 EST ---

Requesting ack flags for 5.7.
Comment 1 Robert Peterson 2011-02-22 21:24:42 UTC 
Requesting ack flags for rhel6
Comment 2 Robert Peterson 2011-04-08 16:23:52 UTC 
Created attachment 490835 [details]
RHEL6 patch

Ran into this bug while working on a customer critsit,
so I had to crosswrite the patch.  So here it is.
Verified it on RHEL6 system gfs-i24c-01.
Comment 3 Robert Peterson 2011-05-26 18:35:17 UTC 
Patch 0ce6e00 was pushed to the RHEL6 branch of the cluster.git
tree for inclusion into 6.2.  Changing status to POST until this
gets built.
Comment 4 Robert Peterson 2011-05-26 18:35:17 UTC 
    Technical note added. If any revisions are required, please edit the "Technical Notes" field
    accordingly. All revisions will be proofread by the Engineering Content Services team.
    
    New Contents:
Cause
A user performs the command "gfs2_edit savemeta" to save off the metadata for a target GFS2 file system.  However, not all of the directory information is saved for large directories.  If the metadata is restored to another device, fsck.gfs2 will find directory corruption due to missing leaf blocks.

Consequence
The bug was caused because gfs2_edit was treating the directory leaf index (known as the directory hash table) like it did a normal data file.  In other words, a collection of metadata blocks.  For a normal data file gfs2_edit needs to save only the metadata blocks, but not the user's data blocks.  For a directory, gfs2_edit needs to save the "data" because the "data" blocks are the actual
directory hash table, and the blocks beneath it are the directory leaf blocks that also need to be saved.

Fix
The fix was to change gfs2_edit's savemeta function to actually read all the data (i.e. the directory hash table) for large directories and traverse the hash table, saving all the leaf blocks.

Result
With the directory hash table processed properly, all leaf blocks are saved properly.
Comment 5 Fabio Massimo Di Nitto 2011-05-27 06:48:41 UTC 
The original commit landed at the wrong time and I had to revert/reapply.

New sha1 is: 258fd452647c6210e68f9528c723e3a49d77dbfa
Comment 9 errata-xmlrpc 2011-12-06 14:50:54 UTC 
Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory, and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

http://rhn.redhat.com/errata/RHBA-2011-1516.html