On Fri, Feb 24, 2017 at 07:23:42AM -0500, Austin S. Hemmelgarn wrote: > On 2017-02-23 19:54, Qu Wenruo wrote: > > > > > > At 02/23/2017 06:51 PM, Christian Theune wrote: > > > Hi, > > > > > > not sure whether it’s possible, but we tried space_cache=v2 and > > > obviously after working fine in staging it broke in production. Or > > > rather: we upgraded from 4.4 to 4.9 and enabled the space_cache. Our > > > production volume is around 50TiB usable (underlying HW Raid 6). > > > > > > The machine crashes silently every 15 hours or so and takes _ages_ to > > > reboot. It current is stuck trying to mount the local filesystems and > > > I guess btrfs is doing something, but I don’t have shell access yet. > > > > > > I’m wondering whether we can downgrade by booting back into 4.4 or > > > will this break things even further? (We’ve had some unpleasant > > > surprises with FS’ in the last months, so I thought I’d rather ask.) > > > > You could use "btrfs check --clear-space-cache" to completely cleanup > > space cache. Both v1(free space cache, file based) or v2(free space > > tree) are supported. > > > > And specially for v2 space cache (space cache tree), "btrfs check > > --clear-space-cache" will also clear the ro_compat flag, so older kernel > > should mount the fs without problem. > That's really good to know. I hadn't remembered that using mount options > didn't clear the flag.
Mounting with -oclear_cache,nospace_cache will clear the free space tree and the ro_compat flag. Mounting with just -oclear_cache rebuilds the free space tree (and keeps the ro_compat flag). -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
