On 2020/2/2 上午4:40, Marc Lehmann wrote: > Hi! > > I upgraded one machine from 5.2.21 to 5.4.15, and one (freshly-created) > btrfs filesystem wrongly shows 0 avail in df after writing a bit of data: > > Filesystem Size Used Avail Use% Mounted on > /dev/mapper/vg_ssd-data 6.5G 160M 0 100% /ssd > > When at the same time, the filesystem should claim gobs of free space > (the df output corresponds to a time a bit earlier when not all data was > written yet): > > Overall: > Device size: 6.00GiB > Device allocated: 0.63GiB > Device unallocated: 5.37GiB > Device missing: 0.00GiB > Used: 0.22GiB > Free (estimated): 5.77GiB (min: 5.77GiB) > Data ratio: 1.00 > Metadata ratio: 1.00 > Global reserve: 0.00GiB (used: 0.00GiB) > > Data,single: Size:0.62GiB, Used:0.22GiB > /dev/mapper/vg_ssd-data 0.62GiB > > Metadata,single: Size:0.01GiB, Used:0.00GiB > /dev/mapper/vg_ssd-data 0.01GiB > > System,single: Size:0.00GiB, Used:0.00GiB > /dev/mapper/vg_ssd-data 0.00GiB > > Unallocated: > /dev/mapper/vg_ssd-data 5.37GiB > > This didn't happen under 5.2.21 for me, obviously. > > Deleting some files makes the remaining space appear again, creating > them again changes to 0 free. I retried with a 76G partition but had > essentially the same results. > > Only df output seems affected, the fs is still writable (I only realized > because apt told me the disk was full - the fs only stores apt package > lists and the apt cache). > > When writing, this switch to 0 free happens suddenly (example with bigger > partition): > > /dev/mapper/vg_ssd-data 76G 3.9M 76G 1% /ssd > /dev/mapper/vg_ssd-data 76G 3.9M 76G 1% /ssd > /dev/mapper/vg_ssd-data 76G 122M 76G 1% /ssd > /dev/mapper/vg_ssd-data 76G 201M 0 100% /ssd > /dev/mapper/vg_ssd-data 76G 244M 0 100% /ssd > > Mount options are noatime,nossd,discard. > > I see there were multiple reports for this and some discussion in december > (https://www.spinics.net/lists/linux-btrfs/msg95694.html), but apparently > nothing came of it and the bug still persists. > The discussion on how to fix it has finally settled down. https://patchwork.kernel.org/patch/11359995/ Will be backported to related stable trees. Thanks, Qu
Attachment:
signature.asc
Description: OpenPGP digital signature
