linux: Btrfs goes forced readonly when qgroup already exists

Tue Dec 23 14:34:50 UTC 2014

Dear Ubuntu Kernel Team,

I would like to request an upstream patch [1] to be applied to the 3.16
kernel.  This patch prevents Btrfs filesystems from going readonly when
a subvolume ID is reused but the corresponding qgroup wasn't destroyed
when the original subvolume was deleted.  This patch has been applied by
upstream to 3.17 [2], but not to 3.16 before it went EOL.  For more
details on the bug, please have a look at the Debian bug log [3].  That
log also contains instructions to reproduce the bug, dmesg output, and
my tests of the patch on various kernel versions.

 [1] https://patchwork.kernel.org/patch/4739211/
 [2] https://git.kernel.org/cgit/linux/kernel/git/stable/linux-stable.git/commit/?id=fe9133f10ca56e54c5f5075a802bc08e61ad8456
 [3] https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=769576

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