1.\" $NetBSD: vnsubr.9,v 1.38 2009/06/02 18:09:34 jnemeth Exp $ 2.\" 3.\" Copyright (c) 2001, 2005, 2006 The NetBSD Foundation, Inc. 4.\" All rights reserved. 5.\" 6.\" This code is derived from software contributed to The NetBSD Foundation 7.\" by Gregory McGarry. 8.\" 9.\" Redistribution and use in source and binary forms, with or without 10.\" modification, are permitted provided that the following conditions 11.\" are met: 12.\" 1. Redistributions of source code must retain the above copyright 13.\" notice, this list of conditions and the following disclaimer. 14.\" 2. Redistributions in binary form must reproduce the above copyright 15.\" notice, this list of conditions and the following disclaimer in the 16.\" documentation and/or other materials provided with the distribution. 17.\" 18.\" THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 19.\" ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 20.\" TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 21.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 22.\" BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 23.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 24.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 25.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 26.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 27.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 28.\" POSSIBILITY OF SUCH DAMAGE. 29.\" 30.Dd June 2, 2009 31.Dt VNSUBR 9 32.Os 33.Sh NAME 34.Nm vnsubr , 35.Nm vn_bwrite , 36.Nm vn_close , 37.Nm vn_default_error , 38.Nm vn_isunder , 39.Nm vn_lock , 40.Nm vn_markexec , 41.Nm vn_marktext , 42.Nm vn_rdwr , 43.Nm vn_restorerecurse , 44.Nm vn_setrecurse , 45.Nm vn_open , 46.Nm vn_stat , 47.Nm vn_writechk 48.Nd high-level convenience functions for vnode operations 49.Sh SYNOPSIS 50.In sys/param.h 51.In sys/lock.h 52.In sys/vnode.h 53.Ft int 54.Fn vn_bwrite "void *ap" 55.Ft int 56.Fn vn_close "struct vnode *vp" "int flags" "kauth_cred_t cred" 57.Ft int 58.Fn vn_default_error "void *v" 59.Ft int 60.Fn vn_isunder "struct vnode *dvp" "struct vnode *rvp" "struct lwp *l" 61.Ft int 62.Fn vn_lock "struct vnode *vp" "int flags" 63.Ft void 64.Fn vn_markexec "struct vnode *vp" 65.Ft void 66.Fn vn_marktext "struct vnode *vp" 67.Ft u_int 68.Fn vn_setrecurse "struct vnode *vp" 69.Ft void 70.Fn vn_restorerecurse "struct vnode *vp" "u_int flags" 71.Ft int 72.Fn vn_open "struct nameidata *ndp" "int fmode" "int cmode" 73.Ft int 74.Fo vn_rdwr 75.Fa "enum uio_rw rw" "struct vnode *vp" "void *base" 76.Fa "int len" "off_t offset" "enum uio_seg segflg" "int ioflg" 77.Fa "kauth_cred_t cred" "size_t *aresid" "struct lwp *l" 78.Fc 79.Ft int 80.Fn vn_readdir "file_t *fp" "char *buf" "int segflg" "u_int count" "int *done" "struct lwp *l" "off_t **cookies" "int *ncookies" 81.Ft int 82.Fn vn_stat "struct vnode *vp" "struct stat *sb" 83.Ft int 84.Fn vn_writechk "struct vnode *vp" 85.Sh DESCRIPTION 86The high-level functions described in this page are convenience 87functions for simplified access to the vnode operations described in 88.Xr vnodeops 9 . 89.Sh FUNCTIONS 90.Bl -tag -width compact 91.It Fn vn_bwrite "ap" 92Common code for block write operations. 93.It Fn vn_close "vp" "flags" "cred" 94Common code for a vnode close. 95The argument 96.Fa vp 97is the unlocked vnode of the vnode to close. 98.Fn vn_close 99simply locks the vnode, invokes the vnode operation 100.Xr VOP_CLOSE 9 101and calls 102.Fn vput 103to return the vnode to the freelist or holdlist. 104Note that 105.Fn vn_close 106expects an unlocked, referenced vnode and will dereference the vnode 107prior to returning. 108If the operation is successful zero is returned, 109otherwise an appropriate error is returned. 110.It Fn vn_default_error "v" 111A generic "default" routine that just returns error. 112It is used by a file system to specify unsupported operations in 113the vnode operations vector. 114.It Fn vn_isunder "dvp" "rvp" "l" 115Common code to check if one directory specified by the vnode 116.Fa rvp 117can be found inside the directory specified by the vnode 118.Fa dvp . 119The argument 120.Fa l 121is the calling process. 122.Fn vn_isunder 123is intended to be used in 124.Xr chroot 2 , 125.Xr chdir 2 , 126.Xr fchdir 2 , 127etc., to ensure that 128.Xr chroot 2 129actually means something. 130If the operation is successful zero is returned, otherwise 1 is returned. 131.It Fn vn_lock "vp" "flags" 132Common code to acquire the lock for vnode 133.Fa vp . 134The argument 135.Fa flags 136specifies the 137.Xr lockmgr 9 138flags used to lock the vnode. 139If the operation is successful zero is returned, otherwise an 140appropriate error code is returned. 141The vnode interlock 142.Em v_interlock 143is released on return. 144.Pp 145.Fn vn_lock 146must not be called when the vnode's reference count is zero. 147Instead, 148.Xr vget 9 149should be used. 150.It Fn vn_markexec "vp" 151Common code to mark the vnode 152.Fa vp 153as containing executable code of a running process. 154.It Fn vn_marktext "vp" 155Common code to mark the vnode 156.Fa vp 157as being the text of a running process. 158.It Fn vn_setrecurse "vp" 159Common code to enable 160.Dv LK_CANRECURSE 161on the vnode lock for vnode 162.Fa vp . 163.Fn vn_setrecurse 164returns the new 165.Xr lockmgr 9 166flags after the update. 167.It Fn vn_restorerecurse "vp" "flags" 168Common code to restore the vnode lock flags for the vnode 169.Fa vp . 170It is called when done with 171.Fn vn_setrecurse . 172.It Fn vn_open "ndp" "fmode" "cmode" 173Common code for vnode open operations. 174The pathname is described in the nameidata pointer (see 175.Xr namei 9 ) . 176The arguments 177.Fa fmode 178and 179.Fa cmode 180specify the 181.Xr open 2 182file mode and the access permissions for creation. 183.Fn vn_open 184checks permissions and invokes the 185.Xr VOP_OPEN 9 186or 187.Xr VOP_CREATE 9 188vnode operations. 189If the operation is successful zero is returned and the vnode is locked, 190otherwise an appropriate error code is returned. 191.It Fn vn_rdwr "rw" "vp" "base" "len" "offset" "segflg" "ioflg" "cred" "aresid" "l" 192Common code to package up an I/O request on a vnode into a uio and 193then perform the I/O. 194The argument 195.Fa rw 196specifies whether the I/O is a read 197.Pq Dv UIO_READ 198or write 199.Pq Dv UIO_WRITE 200operation. 201The vnode is specified by 202.Fa vp . 203The arguments 204.Fa l 205and 206.Fa cred 207are the calling lwp and its credentials. 208If 209.Fa ioflg 210contains 211.Dv IO_NODELOCKED , 212it is expected that the vnode is locked. 213.Fa ioflg 214will be passed to 215.Fn VOP_READ Ns No / Ns Fn VOP_WRITE . 216The remaining arguments specify the uio parameters. 217For further information on these parameters see 218.Xr uiomove 9 . 219.It Fn vn_readdir "fp" "buf" "segflg" "count" "done" "l" "cookies" "ncookies" 220Common code for reading the contents of a directory. 221The argument 222.Fa fp 223is the file structure, 224.Fa buf 225is the buffer for placing the struct dirent structures. 226The arguments 227.Fa cookies 228and 229.Fa ncookies 230specify the addresses for the list and number of directory seek 231cookies generated for NFS. 232Both 233.Fa cookies 234and 235.Fa ncookies 236should be 237.Dv NULL 238if they aren't required to be returned by 239.Fn vn_readdir . 240If the operation is successful zero is returned, otherwise an 241appropriate error code is returned. 242.It Fn vn_stat "vp" "sb" 243Common code for a vnode stat operation. 244The vnode is specified by the argument 245.Fa vp , 246and 247.Fa sb 248is the buffer to return the stat information. 249.Fn vn_stat 250basically calls the vnode operation 251.Xr VOP_GETATTR 9 252and transfers the contents of a vattr structure into a struct stat. 253If the operation is successful zero is returned, otherwise an 254appropriate error code is returned. 255.It Fn vn_writechk "vp" 256Common code to check for write permission on the vnode 257.Fa vp . 258A vnode is read-only if it is in use as a process's text image. 259If the vnode is read-only ETEXTBSY is returned, otherwise zero is 260returned to indicate that the vnode can be written to. 261.El 262.Sh ERRORS 263.Bl -tag -width Er 264.It Bq Er EBUSY 265The LK_NOWAIT flag was set and 266.Fn vn_lock 267would have slept. 268.It Bq Er ENOENT 269The vnode has been reclaimed and is dead. 270This error is only returned if the LK_RETRY flag is not passed to 271.Fn vn_lock . 272.It Bq Er ETXTBSY 273Cannot write to a vnode since is a process's text image. 274.El 275.Sh CODE REFERENCES 276This section describes places within the 277.Nx 278source tree where actual code implementing or using the vnode 279framework can be found. 280All pathnames are relative to 281.Pa /usr/src . 282.Pp 283The high-level convenience functions are implemented within the files 284.Pa sys/kern/vfs_vnops.c 285and 286.Pa sys/sys/vnode.h . 287.Sh SEE ALSO 288.Xr file 9 , 289.Xr intro 9 , 290.Xr lock 9 , 291.Xr namei 9 , 292.Xr vattr 9 , 293.Xr vfs 9 , 294.Xr vnode 9 , 295.Xr vnodeops 9 296