Messages in this thread | | | Subject | Re: [PATCH] [Request for inclusion] Filesystem in Userspace | From | Miklos Szeredi <> | Date | Thu, 25 Nov 2004 08:29:58 +0100 |
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> > There are already "strange" filesystems in the kernel which cannot > > really get rid of dirty data. I'm thinking of tmpfs and ramfs. > > Neither of them are prone to deadlock, though both of them are "worse > > off" than a userspace filesystem, in the sense that they have not even > > the remotest chance of getting rid of the dirty data. > > > > Of course, implementing this is probably not trivial. But I don't see > > it as a theoretical problem as Linus does. > > > > Is there something which I'm missing here? > > But they KNOW that they won't be able to get rid of the dirty data. But > fuse does not.
Why not? I can set bdi->memory_backed to 1 just like ramfs, implement my own writeback thread, and voila, no deadlock.
Of course I believe, that it's probably easier to tweak the page cache to teach it that fuse pages _can_ be written back, but not reliably like a disk filesystem. And there's the small problem of limiting the number of writable pages allocated to FUSE.
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