On Freitag, 22. März 2019 09:41:15 CET Dennis Schridde wrote: > On Freitag, 22. März 2019 09:23:29 CET Coly Li wrote: > > On 2019/3/22 4:18 下午, Dennis Schridde wrote: > > > On Freitag, 22. März 2019 08:04:20 CET Coly Li wrote: > > >> On 2019/3/22 2:14 下午, Coly Li wrote: > > >>> On 2019/3/21 10:16 下午, Coly Li wrote: > > >>>> Now I am able to understand your patch. Yes this patch may > > >>>> fix one of the condition that jset get lost. > > >>>> > > >>>> We should have this fix in v5.1, I will handle the format > > >>>> issue. And if you don't mind I may re-compose a commit log to > > >>>> explain what exactly is fixed. > > >>> > > >>> When I review the patch, I feel there is one point I still do > > >>> not understand, could you please give me more hint ? > > >>> > > >>> From your commit log, "so when we doing replay, journals from > > >>> last_seq_wrote to last_seq_now are missing.", can you show me > > >>> the code to explain how such condition happens ? > > >> > > >> Aha, I realize this is for discard enabled condition. Hmm, but > > >> discard is disabled by default. > > >> > > >> Hi Dennis, > > >> > > >> Is discard enabled in your environment ? Or it is just disabled > > >> by default. > > > > > > How do I figure that out? (I currently only have access to /etc, > > > my previous 4.18 or 4.19 kernel build config and whatever metadata > > > bcache tools can provide me with.) > > > > Hi Dennis, > > > > The sysfs interface is /sys/fs/bcache/<cacheset UUID>/cache0/discard > > > > By default it should be 0 (disabled). > > I used a Fedora 29 live system with Linux 4.18.16-300.fc29. /sys/fs/bcache > is empty except for "regiter" and "register_quiet". Probably because the > bcache kernel module unregisters the cache set after encountering the I/O > errors? bcache-super-show was helpful: $ sudo bcache-super-show /dev/nvme0n1 sb.magic ok sb.first_sector 8 [match] sb.csum HEX1 [match] sb.version 3 [cache device] dev.label (empty) dev.uuid UUID1 dev.sectors_per_block 8 dev.sectors_per_bucket 4096 dev.cache.first_sector 4096 dev.cache.cache_sectors 488390656 dev.cache.total_sectors 488394752 dev.cache.ordered yes dev.cache.discard yes dev.cache.pos 0 dev.cache.replacement 0 [lru] cset.uuid UUID0 $ sudo bcache-super-show /dev/sda3 sb.magic ok sb.first_sector 8 [match] sb.csum HEX2 [match] sb.version 1 [backing device] dev.label (empty) dev.uuid UUID2 dev.sectors_per_block 8 dev.sectors_per_bucket 4096 dev.data.first_sector 16 dev.data.cache_mode 1 [writeback] dev.data.cache_state 2 [dirty] cset.uuid UUID0
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