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xfs_growfs causing "Metadata corruption detected at xfs_agf_read_verify"

DISCUSSION Richard W.M. Jones 3 participants 4 messages Mar 17, 2016 – Mar 20, 2016

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With recent kernels (or maybe xfsprogs?) we've noticed strange filesystem corruption after using xfs_growfs.

Examples:

https://bugzilla.redhat.com/show_bug.cgi?id=1315895 (on aarch64)
https://www.redhat.com/archives/libguestfs/2016-March/msg00113.html (x86_64)
https://rwmj.wordpress.com/2015/11/04/virt-builder-fedora-23-image/#comment-15668 (x86_64)

Do these errors look familiar? I don't yet have a simple test case, still working on that.

Rich.

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Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
Read my programming and virtualization blog: http://rwmj.wordpress.com
virt-builder quickly builds VMs from scratch
http://libguestfs.org/virt-builder.1.html

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#1 lore raw
Quoted 4 lines · Richard W.M. Jones

With recent kernels (or maybe xfsprogs?) we've noticed strange filesystem corruption after using xfs_growfs.

Quoted 8 lines

Examples:

https://bugzilla.redhat.com/show_bug.cgi?id=1315895 (on aarch64)
https://www.redhat.com/archives/libguestfs/2016-March/msg00113.html (x86_64)
https://rwmj.wordpress.com/2015/11/04/virt-builder-fedora-23-image/#comment-15668 (x86_64)

Do these errors look familiar? I don't yet have a simple test case, still working on that.

try:
http://oss.sgi.com/pipermail/xfs/2016-March/047683.html

-Eric

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#2 lore raw
Quoted 11 lines · Eric Sandeen
Quoted 10 lines · Richard W.M. Jones

With recent kernels (or maybe xfsprogs?) we've noticed strange filesystem corruption after using xfs_growfs.

Examples:

https://bugzilla.redhat.com/show_bug.cgi?id=1315895 (on aarch64)
https://www.redhat.com/archives/libguestfs/2016-March/msg00113.html (x86_64)
https://rwmj.wordpress.com/2015/11/04/virt-builder-fedora-23-image/#comment-15668 (x86_64)

Quoted 5 lines
Quoted 2 lines

Do these errors look familiar? I don't yet have a simple test case, still working on that.

try:
http://oss.sgi.com/pipermail/xfs/2016-March/047683.html

I've tried this patch now, but I still can't get a solid reproducer (one that doesn't involve using aarch64).

I just tried to create a filesystem on kernel 4.6.0, grow it on 4.6.0, then copy it to another machine with 4.4.4. However that didn't reproduce the bug, so I couldn't verify if the patch fixes the bug. (Maybe 4.4.4 is too new?)

Can you help me to understand under what circumstances this bug would appear, as far as you understand what's happening?

Rich.

Signature · 10 lines
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
Read my programming and virtualization blog: http://rwmj.wordpress.com
virt-p2v converts physical machines to virtual machines.  Boot with a
live CD or over the network (PXE) and turn machines into KVM guests.
http://libguestfs.org/virt-v2v

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#3 lore raw
Quoted 18 lines · Richard W.M. Jones
Quoted 11 lines · Eric Sandeen
Quoted 10 lines · Richard W.M. Jones

With recent kernels (or maybe xfsprogs?) we've noticed strange filesystem corruption after using xfs_growfs.

Examples:

https://bugzilla.redhat.com/show_bug.cgi?id=1315895 (on aarch64)
https://www.redhat.com/archives/libguestfs/2016-March/msg00113.html (x86_64)
https://rwmj.wordpress.com/2015/11/04/virt-builder-fedora-23-image/#comment-15668 (x86_64)

Quoted 5 lines
Quoted 2 lines

Do these errors look familiar? I don't yet have a simple test case, still working on that.

try:
http://oss.sgi.com/pipermail/xfs/2016-March/047683.html

Quoted 7 lines

I've tried this patch now, but I still can't get a solid reproducer (one that doesn't involve using aarch64).

I just tried to create a filesystem on kernel 4.6.0, grow it on 4.6.0, then copy it to another machine with 4.4.4. However that didn't reproduce the bug, so I couldn't verify if the patch fixes the bug. (Maybe 4.4.4 is too new?)

4.4.4 has the fix already in it, through the stable kernel backport process. i.e. the original kernel commit had this in it:

	 cc: <[email protected]> # 3.10 - 4.4

And so the fix is automatically appearing in stable kernels as they are released. Hence the number of current supported kernels you can reproduce this on is shrinking....

Quoted 2 lines

Can you help me to understand under what circumstances this bug would appear, as far as you understand what's happening?

Take a stock 4.5.0 kernel, mkfs, mount, growfs, unmount go back to a stock 4.4.0 kernel, mount (fails), xfs_repair v4.3.0 (warns, fixes), xfs_repair v4.5.0 (clean, fixes).

Cheers,

Dave.

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Dave Chinner
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