Prefaulting for i/o buffers

[Attilio Rao]

2012/3/1, Gleb Kurtsou <gleb.kurtsou at gmail.com>:
> On (25/02/2012 20:46), Pawel Jakub Dawidek wrote:

[snip]

>> When looking at the big picture, it would be nice to have all this
>> general stuff like rangelocking, quota, buffer cache, etc. as some kind
>> of libraries for file systems to use and not something that is
>> mandatory. If I develop a file system for FreeBSD only and I don't want
>> to reinvent the wheel, I can use those libraries. If I port file system
>> to FreeBSD or develop a file system that doesn't really need those
>> libraries I'm not forced to use them.
>
> Are you aware of a real "libraries for file systems" VFS example? It
> sounds very interesting but I'm afraid it's going to look good only in
> theory. E.g. locking at file system level (Darwin, Dragonfly BSD) looks
> rather messy (IMHO) and more likely to be bug prone. On the other side
> Linux has optional per file system rename lock making VOP_RENAME
> implementation much easier, while ours is tremendously difficult to do
> right.

I think Jeff (CC'ed) had fixed this (maybe only for UFS, cannot recall
now) and he had a very good reason for not using Linux approach, which
I don't recall now.

Thanks,
Attilio


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