Date: Thu, 1 Mar 2012 14:36:19 +0000 From: Attilio Rao <attilio@freebsd.org> To: Gleb Kurtsou <gleb.kurtsou@gmail.com> Cc: Konstantin Belousov <kostikbel@gmail.com>, arch@freebsd.org, Jeff Roberson <jeff@freebsd.org>, Pawel Jakub Dawidek <pjd@freebsd.org> Subject: Re: Prefaulting for i/o buffers Message-ID: <CAJ-FndAfQz5UvnMe3PaNKmjmUy08xLAm37W68HgX-UNkmH8t_Q@mail.gmail.com> In-Reply-To: <20120301111624.GB30991@reks> References: <20120203193719.GB3283@deviant.kiev.zoral.com.ua> <CAJ-FndABi21GfcCRTZizCPc_Mnxm1EY271BiXcYt9SD_zXFpXw@mail.gmail.com> <20120225151334.GH1344@garage.freebsd.pl> <CAJ-FndBBKHrpB1MNJTXx8gkFXR2d-O6k5-HJeOAyv2DznpN-QQ@mail.gmail.com> <20120225194630.GI1344@garage.freebsd.pl> <20120301111624.GB30991@reks>
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2012/3/1, Gleb Kurtsou <gleb.kurtsou@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 -- Peace can only be achieved by understanding - A. Einstein
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