I've frequently seen free space cache corruption lead to phantom ENOSPC. You could try clearing the space cache, and/or mounting with nospache_cache.
On Thu, Dec 1, 2016 at 6:55 AM, Stefan Priebe - Profihost AG <s.pri...@profihost.ag> wrote: > > Am 01.12.2016 um 09:12 schrieb Andrei Borzenkov: >> On Thu, Dec 1, 2016 at 10:49 AM, Stefan Priebe - Profihost AG >> <s.pri...@profihost.ag> wrote: >> ... >>> >>> Custom 4.4 kernel with patches up to 4.10. But i already tried 4.9-rc7 >>> which does the same. >>> >>> >>>>> # btrfs filesystem show /ssddisk/ >>>>> Label: none uuid: a69d2e90-c2ca-4589-9876-234446868adc >>>>> Total devices 1 FS bytes used 305.67GiB >>>>> devid 1 size 500.00GiB used 500.00GiB path /dev/vdb1 >>>>> >>>>> # btrfs filesystem usage /ssddisk/ >>>>> Overall: >>>>> Device size: 500.00GiB >>>>> Device allocated: 500.00GiB >>>>> Device unallocated: 1.05MiB >>>> >>>> Drive is actually fully allocated so if Btrfs needs to create a new >>>> chunk right now, it can't. However, >>> >>> Yes but there's lot of free space: >>> Free (estimated): 193.46GiB (min: 193.46GiB) >>> >>> How does this match? >>> >>> >>>> All three chunk types have quite a bit of unused space in them, so >>>> it's unclear why there's a no space left error. >>>> >> >> I remember discussion that balance always tries to pre-allocate one >> chunk in advance, and I believe there was patch to correct it but I am >> not sure whether it was merged. > > Is there otherwise a possibility to make the free space unallocated again? > > Stefan > >> >>>> Try remounting with enoscp_debug, and then trigger the problem again, >>>> and post the resulting kernel messages. >>> >>> With enospc debug it says: >>> [39193.425682] BTRFS warning (device vdb1): no space to allocate a new >>> chunk for block group 839941881856 >>> [39193.426033] BTRFS info (device vdb1): 1 enospc errors during balance >>> > -- > 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 -- 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
