On Fri, Nov 4, 2022 at 9:37 PM Matias Bjørling <m@xxxxxxxxxxx> wrote: > > On 03/11/2022 07.11, Juhyung Park wrote: > ... > > > > Is the idea really an utter madness? Majority of regular files that may > > be of interest from the perspective of UFS aren't reflinked or > > snapshotted (let alone the lack of support from ext4 or f2fs). > > > > Device-side fragmentation is a real issue [1] and it makes more than > > enough sense to defrag LBAs of interests to improve performance. This > > was long overdue, unless the block interface itself changes somehow. > > There are ongoing work with UFS to extend the block interface with > zones. This approach eliminates the mismatch between the device-side > mapping and host-side mapping and lets the host and device collaborate > on the data placement. > > > > > The question is how to implement it correctly without creating a mess > > with mismatched/outdated LBAs as you've mentioned, preferably through > > file-system's integration: If the LBAs in questions are indeed > > reflinked, how do we handle it?, If the LBAs are moved/invalidated from > > defrag or GC, how do we make sure that UFS is up-to-date?, etc. > > If using zoned UFS, the file-system can use zones for LBA tracking, > eliminating the mismatched/outdated LBA issue. f2fs already supports > this approach (works today with SMR HDDs and ZNS SSDs). It'll extend to > UFS when zone support is added/implemented. > More reasons to have this functionality integrated with the file-system instead of allowing users to specify random LBA ranges.
