One of my btrfs partition seems to have been corrupted.

Since I've tried to balance it, I can only mount it read-only. I have been able to use it read-only without problem so far so the data seems safe.

When I remove the "ro" option, the "mount" command hangs and some programs do not function properly (iotop hangs too and Firefox cannot load new web pages). Every few seconds a message is printed on syslog (see attached file).

If I try to terminate the "mount" process with ctrl+c, my whole system hangs.

This partition was converted from ext4 and I could use it fine after that. It got corrupted when I tried to balance it a few days ago (even though I think I had balanced it before, but I'm not sure about this). The balance would seem to have started but "balance status" showed no progress even after one hour.

This partition is on one hard disk (no raid). Mount options: defaults,compress=lzo,noatime,nodiratime,noauto,ro). My system also runs on btrfs on another disk (ssd) without any problems apart from quite poor performance (but that's for another post).

The command "btrfs scrub start /_big -r" hangs my system.

The command Konsole output "btrfs check /dev/sdb1" outputs :
"Checking filesystem on /dev/sdb1
UUID: 21873ba7-438a-4fbf-a051-ace28bffd264
checking extents"
and stops after a few minutes with no other output.

I did not try "btrfs check --repair".

"Btrfs-zero-log" doesn't seem to apply here.
Konsole output
I could copy the data on another freshly formatted disk and reformat this one but I am wondering if btrfs is stable enough to be used on my professional laptop (where I cannot afford such downtime)or if I should go back to ext4.

So the goal of this message is not only to see if I can repair this partition, but also to assess if btrfs corrupt partitions randomly and irreversibly. If the root cause resides in a non-essential feature (conversion or balancing for example), I would happily continue to use it without this feature.

This is my first message on this mailing list. I've spent the last hours trying to solve this.

More info:

uname -a
Linux viybel-pc 3.19.0-21-generic #21-Ubuntu SMP Sun Jun 14 18:31:11 UTC 2015 x86_64 x86_64 x86_64 GNU/Linux

btrfs --version
btrfs-progs v3.19.1

btrfs fi show
Label: none  uuid: 358f485d-690d-436d-ad35-3a1f47329ed7
         Total devices 1 FS bytes used 107.75GiB
         devid    1 size 111.79GiB used 111.79GiB path /dev/sda1

Label: none  uuid: 21873ba7-438a-4fbf-a051-ace28bffd264
         Total devices 1 FS bytes used 606.17GiB
         devid    1 size 698.63GiB used 660.03GiB path /dev/sdb1

btrfs fi df /_big
Data, single: total=431.00GiB, used=419.49GiB
System, single: total=32.00MiB, used=64.00KiB
Metadata, single: total=229.00GiB, used=186.67GiB
GlobalReserve, single: total=512.00MiB, used=0.00B

dmesg > dmesg.log (attached)

Konsole outp
Vianney