Re: [PATCH] xfs_repair: junk leaf attribute if count == 0

["Libor Klepáč" <libor.klepac@bcom.cz>]

Hello,

On úterý 13. prosince 2016 10:04:27 CET Eric Sandeen wrote:
> On 12/13/16 4:52 AM, Libor Klep�? wrote:
> > Hello,
> > should this patch possibly fix errors i reported in this thread?
> > https://www.spinics.net/lists/linux-xfs/msg01728.html
> > 
> > Is it safe to test it? (i do have backups)
> 
> It should be safe, yes.
> 
> (you could always run xfs_repair -n first to be extra careful).
> 
> Were those errors during mount/replay, though, or was it when the
> filesystem was up and running?
> 
> I ask because I also sent a patch to ignore these empty attributes
> in the verifier during log replay.

Is that patch in 4.8.11 kernel?
I ask, because i rebooted machine from this email
https://www.spinics.net/lists/linux-xfs/msg02672.html

with kernel 4.8.11-1~bpo8+1 (from debian)
mount was clean 
[    3.220692] SGI XFS with ACLs, security attributes, realtime, no debug enabled
[    3.222135] XFS (dm-2): Mounting V4 Filesystem
[    3.284697] XFS (dm-2): Ending clean mount


and i ran xfs_repair -n -v (xfsprogs 4.8.0 without your patch) and it came clean I think
---------------------------------
#xfs_repair -n -v /dev/dm-2
Phase 1 - find and verify superblock...
        - block cache size set to 758064 entries
Phase 2 - using internal log
        - zero log...
zero_log: head block 5035 tail block 5035
        - scan filesystem freespace and inode maps...
        - found root inode chunk
Phase 3 - for each AG...
        - scan (but don't clear) agi unlinked lists...
        - process known inodes and perform inode discovery...
        - agno = 0
        - agno = 1
        - agno = 2
        - agno = 3
        - agno = 4
        - agno = 5
        - agno = 6
        - agno = 7
        - agno = 8
        - agno = 9
        - agno = 10
        - agno = 11
        - agno = 12
        - agno = 13
        - agno = 14
        - agno = 15
        - agno = 16
        - agno = 17
        - agno = 18
        - agno = 19
        - agno = 20
        - agno = 21
        - agno = 22
        - agno = 23
        - agno = 24
        - process newly discovered inodes...
Phase 4 - check for duplicate blocks...
        - setting up duplicate extent list...
        - check for inodes claiming duplicate blocks...
        - agno = 0
        - agno = 1
        - agno = 2
        - agno = 3
        - agno = 4
        - agno = 5
        - agno = 6
        - agno = 7
        - agno = 8
        - agno = 9
        - agno = 10
        - agno = 11
        - agno = 12
        - agno = 13
        - agno = 14
        - agno = 15
        - agno = 16
        - agno = 17
        - agno = 18
        - agno = 19
        - agno = 20
        - agno = 21
        - agno = 22
        - agno = 23
        - agno = 24
No modify flag set, skipping phase 5
Phase 6 - check inode connectivity...
        - traversing filesystem ...
        - agno = 0
        - agno = 1
        - agno = 2
        - agno = 3
        - agno = 4
        - agno = 5
        - agno = 6
        - agno = 7
        - agno = 8
        - agno = 9
        - agno = 10
        - agno = 11
        - agno = 12
        - agno = 13
        - agno = 14
        - agno = 15
        - agno = 16
        - agno = 17
        - agno = 18
        - agno = 19
        - agno = 20
        - agno = 21
        - agno = 22
        - agno = 23
        - agno = 24
        - traversal finished ...
        - moving disconnected inodes to lost+found ...
Phase 7 - verify link counts...
No modify flag set, skipping filesystem flush and exiting.

        XFS_REPAIR Summary    Tue Dec 20 06:01:14 2016

Phase           Start           End             Duration
Phase 1:        12/20 05:49:02  12/20 05:49:02
Phase 2:        12/20 05:49:02  12/20 05:49:02
Phase 3:        12/20 05:49:02  12/20 05:59:24  10 minutes, 22 seconds
Phase 4:        12/20 05:59:24  12/20 06:00:17  53 seconds
Phase 5:        Skipped
Phase 6:        12/20 06:00:17  12/20 06:01:13  56 seconds
Phase 7:        12/20 06:01:13  12/20 06:01:14  1 second

Total run time: 12 minutes, 12 seconds
---------------------------------

then i ran metadump and then i ran out of time of my repair window ;)



Libor


> 
> FWIW, Only some of your reported buffers look "empty" though, the one
> at 514098.682726 may have had something else wrong.
> 
> Anyway, yes, probably worth checking with xfs_repair (-n) with this
> patch added.  Let us know what you find! :)
> 
> -Eric
> 
>  
> > Thanks,
> > Libor
> > 
> > On ?tvrtek 8. prosince 2016 12:06:03 CET Eric Sandeen wrote:
> >> We have recently seen a case where, during log replay, the
> >> attr3 leaf verifier reported corruption when encountering a
> >> leaf attribute with a count of 0 in the header.
> >>
> >> We chalked this up to a transient state when a shortform leaf
> >> was created, the attribute didn't fit, and we promoted the
> >> (empty) attribute to the larger leaf form.
> >>
> >> I've recently been given a metadump of unknown provenance which actually
> >> contains a leaf attribute with count 0 on disk.  This causes the
> >> verifier to fire every time xfs_repair is run:
> >>
> >>  Metadata corruption detected at xfs_attr3_leaf block 0x480988/0x1000
> >>
> >> If this 0-count state is detected, we should just junk the leaf, same
> >> as we would do if the count was too high.  With this change, we now
> >> remedy the problem:
> >>
> >>  Metadata corruption detected at xfs_attr3_leaf block 0x480988/0x1000
> >>  bad attribute count 0 in attr block 0, inode 12587828
> >>  problem with attribute contents in inode 12587828
> >>  clearing inode 12587828 attributes
> >>  correcting nblocks for inode 12587828, was 2 - counted 1
> >>
> >> Signed-off-by: Eric Sandeen <sandeen@redhat.com>
> >> ---
> >>
> >> diff --git a/repair/attr_repair.c b/repair/attr_repair.c
> >> index 40cb5f7..b855a10 100644
> >> --- a/repair/attr_repair.c
> >> +++ b/repair/attr_repair.c
> >> @@ -593,7 +593,8 @@ process_leaf_attr_block(
> >>  	stop = xfs_attr3_leaf_hdr_size(leaf);
> >>  
> >>  	/* does the count look sorta valid? */
> >> -	if (leafhdr.count * sizeof(xfs_attr_leaf_entry_t) + stop >
> >> +	if (!leafhdr.count ||
> >> +	    leafhdr.count * sizeof(xfs_attr_leaf_entry_t) + stop >
> >>  						mp->m_sb.sb_blocksize) {
> >>  		do_warn(
> >>  	_("bad attribute count %d in attr block %u, inode %" PRIu64 "\n"),
> >> --
> >> To unsubscribe from this list: send the line "unsubscribe linux-xfs" in
> >> the body of a message to majordomo@vger.kernel.org
> >> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> >>
> > 
> > 
> > --
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> > 
> 


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