Hi folks! The Linux Plumbers conference is next week! The filesystems mini conference is next Tuesday, 21 September, starting at 14:00 UTC: https://linuxplumbersconf.org/event/11/sessions/111/#20210921 (it's the light green column second from the right) As most of you are probably aware, LSFMM has been cancelled for a second year in a row, which leaves LPC as the only developer focused gathering this year. This year's conference is virtual, like last year. If you'd like to participate, it's not too late to register ($50 USD): https://linuxplumbersconf.org/event/11/page/112-attend --- The first session will be run by Matthew Wilcox, who will say something about the ongoing folio work, assuming Linus isn't going to pull it for 5.15. We'll see where things are in a week. Christian Brauner will run the second session, discussing what idmapped filesystem mounts are for and the current status of supporting more filesystems. --- Next up will be a session run by me about both of the atomic file write features that have been variously proposed and asked for by various enterprisey users. The first proposal refers to direct atomic file writes to storage hardware. I /think/ this mostly involves enabling the relevant plumbing in the block layer and then wiring up iomap/xfs to use it. Possibly also a new pwritev2 flag or file mode or something. (Christoph did this in 2019: https://lwn.net/Articles/789600/ ) The /other/ atomic file write feature, of course, is my longstanding RFC to add a VFS call that enables atomic swapping of file contents, which enables a program to reflink a file's contents to an O_TMPFILE file, write some changes to the tempfile, and then swap /all/ the changed blocks back to the original file. This call would be durable even if the system goes down. The feature is actually the brainchild of the online filesystem repair effort, but I figured it wasn't so hard to extend a tendril to userspace to make it more generally useful. https://lwn.net/Articles/818977/ https://lore.kernel.org/linux-fsdevel/161723932606.3149451.12366114306150243052.stgit@magnolia/ --- Allison will be running the fourth session about our current progress towards enabling sysadmins to shrink filesystems, and what pieces we're going to need to clear space from the end of the filesystem and then reduce the size. FWIW Dave has been working on an inode relocation ("reno") tool, and I've been working on a free space defragmenter that kind of barely works. Originally this was a XFS-focused discussion, but it seems that Andreas still remembers the last time someone tried to add it to ext4. --- Session #4 discusses the proliferation of cloud storage technologies and the new failure modes that Ted and I have observed with these devices. I think Ted had a few things to say about cloud devices, and due to the repeated requests I think it would be worth polling the audience to find out if they'd like filesystems to be more resilient (when possible) in the face of not-totally-reliable storage. Obviously everyone wants that as a broad goal, but what should we pitch? Metadata IO retries? Restoring lost information from a mirror? Online repair? --- The final session will be a presentation about the XFS roadmap for 2022. I'll start with a recap of the new features from last year's LTS that have been maturing this year, and which pieces have landed for this year's LTS kernel. I /hope/ that this will attract a conversation between (x)fs developers and real application developers about what features could be coming down the pipeline and what features would they most be interested in. --- To all the XFS developers: it has been a very long time since I've seen all your faces! I would love to have a developer BOF of some kind to see you all again, and to introduce Catherine Hoang (our newest addition) to the group. If nobody else shows up to the roadmap we could do it there, but I'd like to have /some/ kind of venue for everyone who don't find the timeslots convenient (i.e. Dave and Chandan). This doesn't have to take a long time -- even a 15 minute meet and greet to help everyone (re)associate names with faces would go a long way towards feeling normal(ish) again. ;) --D
