Date: Sun, 15 Aug 1999 15:47:40 -0700 (PDT) From: John Polstra <jdp@polstra.com> To: Alfred Perlstein <bright@rush.net> Cc: hackers@FreeBSD.ORG Subject: Re: Getting device and inode number from a vnode Message-ID: <XFMail.990815154740.jdp@polstra.com> In-Reply-To: <Pine.BSF.3.96.990815181303.20420B-100000@cygnus.rush.net>
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Alfred Perlstein wrote: > On Sun, 15 Aug 1999, John Polstra wrote: >> >> 1. I have a pointer to a vnode and I want to get the corresponding >> dev_t and inode number. Is there a non-sleazy way to do that other >> than calling vn_stat? > > use vn_todev from "vfs_subr.c" ~line 2970 of 2976 if you just > need the dev_t. Thanks. I didn't make it clear in my question, but I want the dev_t of the filesystem containing the file (st_dev rather than st_rdev). > but you may wind up needing the GETATTR call for the inode lookup. OK. >> 2. The first action of vn_stat is to call VOP_GETATTR. VOP_GETATTR(9) >> says, "The file should not be locked on entry." But when stat calls >> vn_stat, the vnode is locked. Which is correct -- or doesn't it >> matter? > > the lookup at the begininngin of the stat() call's side-effect is to > lock the vnode it returns but kern/vnode.src seems to indicate > that the vnode's locking state doesn't matter... Ah, good. That helps. > so does the various states that vnodes are in when called from > vfs_syscalls, such as the lseek syscall. Yes, and fstat doesn't lock it either. > it's slighly confusing, if the vnode is locked for "access" calls > why is it not locked for attribute calls? I'm confused too. :-) John --- John Polstra jdp@polstra.com John D. Polstra & Co., Inc. Seattle, Washington USA "No matter how cynical I get, I just can't keep up." -- Nora Ephron To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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