On Wed, Oct 10, 2018 at 10:04 AM, Holger Hoffstätte <hol...@applied-asynchrony.com> wrote: > On 10/10/18 17:44, Larkin Lowrey wrote: > (..) >> >> About once a week, or so, I'm running into the above situation where >> FS seems to deadlock. All IO to the FS blocks, there is no IO >> activity at all. I have to hard reboot the system to recover. There >> are no error indications except for the following which occurs well >> before the FS freezes up: >> >> BTRFS warning (device dm-3): block group 78691883286528 has wrong amount >> of free space >> BTRFS warning (device dm-3): failed to load free space cache for block >> group 78691883286528, rebuilding it now >> >> Do I have any options other the nuking the FS and starting over? > > > Unmount cleanly & mount again with -o space_cache=v2.
I'm pretty sure you have to umount, and then clear the space_cache with 'btrfs check --clear-space-cache=v1' and then do a one time mount with -o space_cache=v2. But anyway, to me that seems premature because we don't even know what's causing the problem. a. Freezing means there's a kernel bug. Hands down. b. Is it freezing on the rebuild? Or something else? c. I think the devs would like to see the output from btrfs-progs v4.17.1, 'btrfs check --mode=lowmem' and see if it finds anything, in particular something not related to free space cache. Rebuilding either version of space cache requires successfully reading (and parsing) the extent tree. -- Chris Murphy
