Comment 6 for bug 1415510

FYI, I'm now running Kernel version 3.19.0-031900rc6-generic from the URL you mentioned in #4. Let's see if the issue persists.

The file system mounts fine, but I'm concerned about the output of btrfsck:

Checking filesystem on /dev/mapper/ubuntu--vg-container
UUID: b95b58fb-d0b2-4735-a4ed-2033537eb89a
checking extents
checking free space cache
free space inode generation (0) did not match free space cache generation (135494)
free space inode generation (0) did not match free space cache generation (135494)
There is no free space entry for 11902451712-11904450560
There is no free space entry for 11902451712-12914262016
cache appears valid but isnt 11840520192
There is no free space entry for 14083878912-14084898816
There is no free space entry for 14083878912-15061745664
cache appears valid but isnt 13988003840
There is no free space entry for 15305744384-15306821632
There is no free space entry for 15305744384-16135487488
cache appears valid but isnt 15061745664
There is no free space entry for 16377102336-16378097664
There is no free space entry for 16377102336-17209229312
cache appears valid but isnt 16135487488
Wanted bytes 1957888, found 393216 for off 17210597376
Wanted bytes 1072373760, found 393216 for off 17210597376
cache appears valid but isnt 17209229312
There is no free space entry for 22839361536-22840332288
There is no free space entry for 22839361536-23651680256
cache appears valid but isnt 22577938432
There is no free space entry for 27126554624-27128291328
There is no free space entry for 27126554624-27946647552
cache appears valid but isnt 26872905728
There is no free space entry for 27985326080-27987566592
There is no free space entry for 27985326080-29020389376
cache appears valid but isnt 27946647552
There is no free space entry for 30126866432-30127960064
There is no free space entry for 30126866432-31167873024
cache appears valid but isnt 30094131200
Wanted bytes 2195456, found 12288 for off 64471998464
Wanted bytes 1055612928, found 12288 for off 64471998464
cache appears valid but isnt 64453869568
There is no free space entry for 65631424512-65632366592
There is no free space entry for 65631424512-66601353216
cache appears valid but isnt 65527611392
free space inode generation (0) did not match free space cache generation (135494)
found 15376998613 bytes used err is -22
total csum bytes: 44021104
total tree bytes: 601505792
total fs tree bytes: 419954688
total extent tree bytes: 103333888
btree space waste bytes: 129058353
file data blocks allocated: 126222901248
 referenced 43301400576
Btrfs v3.12

I'm not sure if the corruption is the cause or the consequence of the kernel panics, which require a hard reboot.