Date: Wed, 21 May 2003 19:18:29 -0700 From: Hiten Pandya <hmp@FreeBSD.ORG> To: arch@FreeBSD.ORG Subject: vnode(9) update Message-ID: <20030522021829.GA6619@perrin.int.nxad.com>
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--ew6BAiZeqk4r7MaW Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Hello Gang. I am requesting a review of removing the ``struct vnode'' from the vnode(9) manual page, and also updating a little text. I was asked by some people to ask arch@ for a review before making such change, so here it is. Patch is attached with this mail. Patch also available from: http://people.FreeBSD.ORG/~hmp/patches/vnode.9.patch Comments and suggestions welcome. Cheers. -- Hiten (hmp@FreeBSD.ORG) --ew6BAiZeqk4r7MaW Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename="vnode.9.patch" Index: vnode.9 =================================================================== RCS file: /home/ncvs/src/share/man/man9/vnode.9,v retrieving revision 1.24 diff -u -r1.24 vnode.9 --- vnode.9 6 Mar 2003 23:55:51 -0000 1.24 +++ vnode.9 20 May 2003 21:28:10 -0000 @@ -1,5 +1,3 @@ -.\" -*- nroff -*- -.\" .\" Copyright (c) 1996 Doug Rabson .\" .\" All rights reserved. @@ -28,7 +26,7 @@ .\" .\" $FreeBSD: src/share/man/man9/vnode.9,v 1.24 2003/03/06 23:55:51 ceri Exp $ .\" -.Dd June 30, 1999 +.Dd May 20, 2003 .Os .Dt VNODE 9 .Sh NAME @@ -37,114 +35,20 @@ .Sh SYNOPSIS .In sys/param.h .In sys/vnode.h -.Pp -.Bd -literal -/* - * Vnode types. VNON means no type. - */ -enum vtype { VNON, VREG, VDIR, VBLK, VCHR, VLNK, VSOCK, VFIFO, VBAD }; - -/* - * Each underlying file system allocates its own private area and hangs - * it from v_data. If non-null, this area is freed in getnewvnode(). - */ -TAILQ_HEAD(buflists, buf); - -typedef int vop_t(void *); -struct namecache; - -/* - * Reading or writing any of these items requires holding the appropriate lock. - * v_freelist is locked by the global vnode_free_list simple lock. - * v_mntvnodes is locked by the global mntvnodes simple lock. - * v_flag, v_usecount, v_holdcount and v_writecount are - * locked by the v_interlock simple lock. - * v_pollinfo is locked by the lock contained inside it. - */ -struct vnode { - u_long v_flag; /* vnode flags (see below) */ - int v_usecount; /* reference count of users */ - int v_writecount; /* reference count of writers */ - int v_holdcnt; /* page & buffer references */ - u_long v_id; /* capability identifier */ - struct mount *v_mount; /* ptr to vfs we are in */ - vop_t **v_op; /* vnode operations vector */ - TAILQ_ENTRY(vnode) v_freelist; /* vnode freelist */ - LIST_ENTRY(vnode) v_mntvnodes; /* vnodes for mount point */ - struct buflists v_cleanblkhd; /* clean blocklist head */ - struct buflists v_dirtyblkhd; /* dirty blocklist head */ - LIST_ENTRY(vnode) v_synclist; /* vnodes with dirty buffers */ - long v_numoutput; /* num of writes in progress */ - enum vtype v_type; /* vnode type */ - union { - struct mount *vu_mountedhere;/* ptr to mounted vfs (VDIR) */ - struct socket *vu_socket; /* unix ipc (VSOCK) */ - struct { - struct specinfo *vu_specinfo; /* device (VCHR, VBLK) */ - SLIST_ENTRY(vnode) vu_specnext; - } vu_spec; - struct fifoinfo *vu_fifoinfo; /* fifo (VFIFO) */ - } v_un; - struct nqlease *v_lease; /* Soft reference to lease */ - daddr_t v_lastw; /* last write (write cluster) */ - daddr_t v_cstart; /* start block of cluster */ - daddr_t v_lasta; /* last allocation */ - int v_clen; /* length of current cluster */ - struct vm_object *v_object; /* Place to store VM object */ - struct simplelock v_interlock; /* lock on usecount and flag */ - struct lock *v_vnlock; /* used for non-locking fs's */ - const char *v_tag; /* type of underlying data */ - void *v_data; /* private data for fs */ - LIST_HEAD(, namecache) v_cache_src; /* Cache entries from us */ - TAILQ_HEAD(, namecache) v_cache_dst; /* Cache entries to us */ - struct vnode *v_dd; /* .. vnode */ - u_long v_ddid; /* .. capability identifier */ - struct { - struct simplelock vpi_lock; /* lock to protect below */ - struct selinfo vpi_selinfo; /* identity of poller(s) */ - short vpi_events; /* what they are looking for */ - short vpi_revents; /* what has happened */ - } v_pollinfo; -}; -#define v_mountedhere v_un.vu_mountedhere -#define v_socket v_un.vu_socket -#define v_rdev v_un.vu_spec.vu_specinfo -#define v_specnext v_un.vu_spec.vu_specnext -#define v_fifoinfo v_un.vu_fifoinfo - -/* - * Vnode flags. - */ -#define VROOT 0x00001 /* root of its file system */ -#define VTEXT 0x00002 /* vnode is a pure text prototype */ -#define VSYSTEM 0x00004 /* vnode being used by kernel */ -#define VISTTY 0x00008 /* vnode represents a tty */ -#define VXLOCK 0x00100 /* vnode is locked to change underlying type */ -#define VXWANT 0x00200 /* process is waiting for vnode */ -#define VBWAIT 0x00400 /* waiting for output to complete */ -#define VOBJBUF 0x02000 /* Allocate buffers in VM object */ -#define VAGE 0x08000 /* Insert vnode at head of free list */ -#define VOLOCK 0x10000 /* vnode is locked waiting for an object */ -#define VOWANT 0x20000 /* a process is waiting for VOLOCK */ -#define VDOOMED 0x40000 /* This vnode is being recycled */ -#define VFREE 0x80000 /* This vnode is on the freelist */ -#define VTBFREE 0x100000 /* This vnode is on the to-be-freelist */ -#define VONWORKLST 0x200000 /* On syncer work-list */ -#define VMOUNT 0x400000 /* Mount in progress */ - -.Ed .Sh DESCRIPTION The vnode is the focus of all file activity in .Ux . +A vnode is described by +.Vt "struct vnode" . There is a unique vnode allocated for each active file, each current directory, each mounted-on file, text file, and the root. .Pp Each vnode has three reference counts, -.Dv v_usecount , -.Dv v_holdcnt +.Va v_usecount , +.Va v_holdcnt and -.Dv v_writecount . +.Va v_writecount . The first is the number of clients within the kernel which are using this vnode. This count is maintained by .Xr vref 9 , @@ -158,9 +62,9 @@ and .Xr vdrop 9 . When both the -.Dv v_usecount +.Va v_usecount and the -.Dv v_holdcnt +.Va v_holdcnt of a vnode reaches zero then the vnode will be put on the freelist and may be reused for another file, possibly in another file system. The transition to and from the freelist is handled by @@ -180,7 +84,7 @@ .Xr VOP_LOOKUP 9 etc.) will increase the -.Dv v_usecount +.Va v_usecount of the vnode by one. When the caller is finished with the vnode, it should release this reference by calling .Xr vrele 9 @@ -189,17 +93,17 @@ if the vnode is locked). .Pp Other commonly used members of the vnode structure are -.Dv v_id +.Va v_id which is used to maintain consistency in the name cache, -.Dv v_mount +.Va v_mount which points at the file system which owns the vnode, -.Dv v_type +.Va v_type which contains the type of object the vnode represents and -.Dv v_data +.Va v_data which is used by file systems to store file system specific data with the vnode. The -.Dv v_op +.Va v_op field is used by the .Dv VOP_* macros to call functions in the file system which implement the vnode's --ew6BAiZeqk4r7MaW--
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