Date: Wed, 28 Feb 2001 17:10:02 -0800 (PST) From: John Polstra <jdp@polstra.com> To: arch@freebsd.org Cc: scott_long@btc.adaptec.com Subject: Re: Arch question for a UDF FS driver Message-ID: <200103010110.f211A2843934@vashon.polstra.com> In-Reply-To: <E0BFB46945D5D411BB590000D11ABE9203349F@btcexc01.btc.adaptec.com> References: <E0BFB46945D5D411BB590000D11ABE9203349F@btcexc01.btc.adaptec.com>
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In article <E0BFB46945D5D411BB590000D11ABE9203349F@btcexc01.btc.adaptec.com>, Long, Scott <scott_long@btc.adaptec.com> wrote: > I've starting writing a UDF FS driver for FreeBSD, and am coming to a > decision point. UDF is somewhat similar to ufs in that a File Entry is > analogous to an inode, so I'd like to implement the filesystem using the > vget vfsop. Problem is that vget uses ino_t which is a uint32_t, while the > Unique Id (aka inode number) for UDF is a uint64_t. Unique Id's are > numbered sequentially starting at 16 (0 is the root dir, 1-15 are reserved), > and may be sparse. So what color should I paint the bikeshed? [...] > Orange: Get ino_t bumped up to a uint64_t and modify all the other > filesystems to deal with it accordingly. Advantage: no hackery needed for > UDF. Disadvantage: may be the mother of all bikesheds. Unfortunately, values of type ino_t are passed from kernel to userland via the stat(2) family of system calls. So if you change the size of ino_t, it will change the shape of the stat structure. This would introduce binary compatibility problems. There would have to be yet another flavor of struct stat (we already have 3 of them in <sys/stat.h>), and some new system calls for the new versions of stat(), fstat(), and lstat(). I.e., you can't just change the existing system calls without totally breaking old binaries. It's not a total show-stopper, but it does make that shade of orange look kind of, er, puke colored. :-) John -- John Polstra jdp@polstra.com John D. Polstra & Co., Inc. Seattle, Washington USA "Disappointment is a good sign of basic intelligence." -- Chögyam Trungpa To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-arch" in the body of the message
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