Re: xfs_repair: couldn't map inode 2089979520, err = 117

["Darrick J. Wong" <darrick.wong@oracle.com>]

On Thu, Jan 18, 2018 at 01:36:37PM -0500, Brian Foster wrote:
> On Wed, Jan 17, 2018 at 10:27:19PM -0800, Christian Kujau wrote:
> > Hi,
> > 
> > after a(nother) power outage this disk enclosure (containing two seperate 
> > disks, connected via USB) was acting up and while one of the disks seems 
> > to have died, the other one still works and no more hardware errors are 
> > reported for the enclosure or the disk.
> > 
> > The XFS file system on this disk can be mounted (!) and data can be read, 
> > but an xfs_repair fails to complete: http://nerdbynature.de/bits/4.14/xfs/
> > 
> > I have (compressed) xfs_metadump images available if anyone is interested.
> > 
> > A timeline of events:
> > 
> >  * disk enclosure[0] connected to a Raspbery Pi (aarch64)
> >  * power failure, and possible power spike after power came back
> >  * RPI and disk enclosure disconnected from power.
> >  * disk enclosure connected to an x86-64 machine with lots of RAM
> >  * xfs_repair (Fedora 27, xfsprogs-4.12) attempted, but the disk enclosure
> >    was still trying to handle the other (failing) disk and the repair
> >    failed after some USB resets.
> >  * failed disk was removed from the enclosure, no more hardware errors 
> >    since, but still xfs_repair is unable to complete.
> > 
> > After a chat on #xfs, Eric and Dave remarked:
> > 
> > > error 117 means the inode is corrupted; probably shouldn't be at that 
> > > stage, probably indicates a repair bug? just looking at the first few 
> > > errors
> > > bad magic # 0x49414233 in btbno block 28/134141
> > > bad magic # 0x46494233 in btcnt block 30/870600
> > > the first magic is IAB3 the 2nd is FIB3 those are magic numbers for
> > > xfs, but not for the type of block it thought it was checking
> > 
> > ...and also:
> > 
> > > cross linked btrees does tend to indicate something went badly wrong
> > > at the hardware level
> > 
> > So, with all that (failed xfs_repair runs that were interrupted by 
> > hardware faults and also possibly flaky USB controller[0]) - has anybody 
> > an idea on how to convince xfs_repair to still clean up this mess? Or is 
> > there no other way than to restore from backup?
> > 
> 
> After looking at one of Christian's metadumps, it looks like this is a
> possible regression as of the inline directory fork verification bits. I
> don't have the full cause, but xfs_repair explodes due to the parent
> inode validation in xfs_iformat_fork -> xfs_dir2_sf_verify() when
> processing directory inode 2089979520. A quick test without the verifier
> allows repair to complete.
> 
> Christian, for the time being I suppose you could try a slightly older
> xfs_repair and see if that gets you anywhere. v4.10 or so appears to not
> include the associated commits.

Ahhhurrgh.  Yes, right now xfsprogs is rather inflexible about the
verifiers -- the directory repairer decides that it can simply reset the
parent pointer, but then libxfs_iget & friends barf because the sf
directory verifier fails, and there's no way to turn that off.

Well, there /is/ a way -- refactor the sf verifiers such that they're
(optionally) called by _iget so that repair can load the inode w/o
verifiers, make the corrections, and write everything back out.  That
refactoring will appear in Linux 4.16, so I imagine xfs_repair 4.16 will
get back on track with that.

FWIW I think a reasonable reproducer is running xfs/384 with:

SCRATCH_XFS_LIST_METADATA_FIELDS=u3.sfdir3.hdr.parent.i4
SCRATCH_XFS_LIST_FUZZ_VERBS=random

set in the environment (assumes v5 filesystem, etc.)

In the meantime, yeah, what Brian said.

--D

> Brian
> 
> > Thanks,
> > Christian.
> > 
> > [0] When the disk enclosure is connected to the Raspberry Pi 3, the kernel 
> >     usually recognizes it as follows:
> > 
> > usb 1-1.4: new high-speed USB device number 4 using dwc2
> > usb 1-1.4: New USB device found, idVendor=7825, idProduct=a2a8
> > usb 1-1.4: New USB device strings: Mfr=1, Product=2, SerialNumber=5
> > usb 1-1.4: Product: ElitePro Dual U3FW
> > usb 1-1.4: Manufacturer: OWC
> > usb 1-1.4: SerialNumber: DB9876543211160
> > usb 1-1.4: The driver for the USB controller dwc2_hsotg does not support scatter-gather which is
> > usb 1-1.4: required by the UAS driver. Please try an other USB controller if you wish to use UAS.
> > usb 1-1.4: The driver for the USB controller dwc2_hsotg does not support scatter-gather which is
> > usb 1-1.4: required by the UAS driver. Please try an other USB controller if you wish to use UAS.
> > usb-storage 1-1.4:1.0: USB Mass Storage device detected
> > scsi host0: usb-storage 1-1.4:1.0
> > scsi 0:0:0:0: Direct-Access     ElitePro Dual U3FW-1      0006 PQ: 0 ANSI: 6
> > scsi 0:0:0:1: Direct-Access     ElitePro Dual U3FW-2      0006 PQ: 0 ANSI: 6
> > sd 0:0:0:0: Attached scsi generic sg0 type 0
> > sd 0:0:0:0: [sda] Very big device. Trying to use READ CAPACITY(16).
> > sd 0:0:0:0: [sda] 7814037168 512-byte logical blocks: (4.00 TB/3.64 TiB)
> > sd 0:0:0:0: [sda] Write Protect is off
> > sd 0:0:0:0: [sda] Mode Sense: 47 00 10 08
> > sd 0:0:0:0: [sda] No Caching mode page found
> > sd 0:0:0:0: [sda] Assuming drive cache: write through
> > sd 0:0:0:0: [sda] Very big device. Trying to use READ CAPACITY(16).
> > [...] 
> > 
> > 
> > -- 
> > BOFH excuse #449:
> > 
> > greenpeace free'd the mallocs
> > --
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