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NetBSD 6.1.5 - man page for vnsubr (netbsd section 9)

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VNSUBR(9)			  BSD Kernel Developer's Manual 			VNSUBR(9)

NAME
     vnsubr, vn_bwrite, vn_close, vn_default_error, vn_isunder, vn_lock, vn_markexec,
     vn_marktext, vn_rdwr, vn_open, vn_stat, vn_writechk -- high-level convenience functions for
     vnode operations

SYNOPSIS
     #include <sys/param.h>
     #include <sys/lock.h>
     #include <sys/vnode.h>

     int
     vn_bwrite(void *ap);

     int
     vn_close(struct vnode *vp, int flags, kauth_cred_t cred);

     int
     vn_default_error(void *v);

     int
     vn_isunder(struct vnode *dvp, struct vnode *rvp, struct lwp *l);

     int
     vn_lock(struct vnode *vp, int flags);

     void
     vn_markexec(struct vnode *vp);

     void
     vn_marktext(struct vnode *vp);

     int
     vn_open(struct nameidata *ndp, int fmode, int cmode);

     int
     vn_rdwr(enum uio_rw rw, struct vnode *vp, void *base, int len, off_t offset,
	 enum uio_seg segflg, int ioflg, kauth_cred_t cred, size_t *aresid, struct lwp *l);

     int
     vn_readdir(file_t *fp, char *buf, int segflg, u_int count, int *done, struct lwp *l,
	 off_t **cookies, int *ncookies);

     int
     vn_stat(struct vnode *vp, struct stat *sb);

     int
     vn_writechk(struct vnode *vp);

DESCRIPTION
     The high-level functions described in this page are convenience functions for simplified
     access to the vnode operations described in vnodeops(9).

FUNCTIONS
     vn_bwrite(ap)
	      Common code for block write operations.

     vn_close(vp, flags, cred)
	      Common code for a vnode close.  The argument vp is the unlocked vnode of the vnode
	      to close.  vn_close() simply locks the vnode, invokes the vnode operation
	      VOP_CLOSE(9) and calls vput() to return the vnode to the freelist or holdlist.
	      Note that vn_close() expects an unlocked, referenced vnode and will dereference the
	      vnode prior to returning.  If the operation is successful zero is returned, other-
	      wise an appropriate error is returned.

     vn_default_error(v)
	      A generic "default" routine that just returns error.  It is used by a file system
	      to specify unsupported operations in the vnode operations vector.

     vn_isunder(dvp, rvp, l)
	      Common code to check if one directory specified by the vnode rvp can be found
	      inside the directory specified by the vnode dvp.	The argument l is the calling
	      process.	vn_isunder() is intended to be used in chroot(2), chdir(2), fchdir(2),
	      etc., to ensure that chroot(2) actually means something.	If the operation is suc-
	      cessful zero is returned, otherwise 1 is returned.

     vn_lock(vp, flags)
	      Common code to acquire the lock for vnode vp.  The argument flags specifies the
	      flags used to lock the vnode.  There are the following flags:

		    LK_SHARED	  shared lock
		    LK_EXCLUSIVE  exclusive lock
		    LK_NOWAIT	  do not sleep to await lock
		    LK_RETRY	  retry lock operation until locked

	      If the operation is successful zero is returned, otherwise an appropriate error
	      code is returned.  The vnode interlock v_interlock is released on return.

	      vn_lock() must not be called when the vnode's reference count is zero.  Instead,
	      vget(9) should be used.

     vn_markexec(vp)
	      Common code to mark the vnode vp as containing executable code of a running
	      process.

     vn_marktext(vp)
	      Common code to mark the vnode vp as being the text of a running process.

     vn_open(ndp, fmode, cmode)
	      Common code for vnode open operations.  The pathname is described in the nameidata
	      pointer (see namei(9)).  The arguments fmode and cmode specify the open(2) file
	      mode and the access permissions for creation.  vn_open() checks  permissions and
	      invokes the VOP_OPEN(9) or VOP_CREATE(9) vnode operations.  If the operation is
	      successful zero is returned and the vnode is locked, otherwise an appropriate error
	      code is returned.

     vn_rdwr(rw, vp, base, len, offset, segflg, ioflg, cred, aresid, l)
	      Common code to package up an I/O request on a vnode into a uio and then perform the
	      I/O.  The argument rw specifies whether the I/O is a read (UIO_READ) or write
	      (UIO_WRITE) operation.  The vnode is specified by vp.  The arguments l and cred are
	      the calling lwp and its credentials.  If ioflg contains IO_NODELOCKED, it is
	      expected that the vnode is locked.  ioflg will be passed to VOP_READ()/VOP_WRITE().
	      The remaining arguments specify the uio parameters.  For further information on
	      these parameters see uiomove(9).

     vn_readdir(fp, buf, segflg, count, done, l, cookies, ncookies)
	      Common code for reading the contents of a directory.  The argument fp is the file
	      structure, buf is the buffer for placing the struct dirent structures.  The argu-
	      ments cookies and ncookies specify the addresses for the list and number of direc-
	      tory seek cookies generated for NFS.  Both cookies and ncookies should be NULL if
	      they aren't required to be returned by vn_readdir().  If the operation is success-
	      ful zero is returned, otherwise an appropriate error code is returned.

     vn_stat(vp, sb)
	      Common code for a vnode stat operation.  The vnode is specified by the argument vp,
	      and sb is the buffer to return the stat information.  vn_stat() basically calls the
	      vnode operation VOP_GETATTR(9) and transfers the contents of a vattr structure into
	      a struct stat.  If the operation is successful zero is returned, otherwise an
	      appropriate error code is returned.

     vn_writechk(vp)
	      Common code to check for write permission on the vnode vp.  A vnode is read-only if
	      it is in use as a process's text image.  If the vnode is read-only ETEXTBSY is
	      returned, otherwise zero is returned to indicate that the vnode can be written to.

ERRORS
     [EBUSY]		The LK_NOWAIT flag was set and vn_lock() would have slept.

     [ENOENT]		The vnode has been reclaimed and is dead.  This error is only returned if
			the LK_RETRY flag is not passed to vn_lock().

     [ETXTBSY]		Cannot write to a vnode since is a process's text image.

CODE REFERENCES
     The high-level convenience functions are implemented within the files sys/kern/vfs_vnops.c
     and sys/sys/vnode.h.

SEE ALSO
     file(9), intro(9), lock(9), namei(9), vattr(9), vfs(9), vnode(9), vnodeops(9)

BSD					 January 30, 2010				      BSD
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