xref: /csrg-svn/sys/kern/vfs_subr.c (revision 38258)
137488Smckusick /*
237488Smckusick  * Copyright (c) 1989 The Regents of the University of California.
337488Smckusick  * All rights reserved.
437488Smckusick  *
537488Smckusick  * Redistribution and use in source and binary forms are permitted
637488Smckusick  * provided that the above copyright notice and this paragraph are
737488Smckusick  * duplicated in all such forms and that any documentation,
837488Smckusick  * advertising materials, and other materials related to such
937488Smckusick  * distribution and use acknowledge that the software was developed
1037488Smckusick  * by the University of California, Berkeley.  The name of the
1137488Smckusick  * University may not be used to endorse or promote products derived
1237488Smckusick  * from this software without specific prior written permission.
1337488Smckusick  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
1437488Smckusick  * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
1537488Smckusick  * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
1637488Smckusick  *
17*38258Smckusick  *	@(#)vfs_subr.c	7.2 (Berkeley) 06/07/89
1837488Smckusick  */
1937488Smckusick 
2037488Smckusick /*
2137488Smckusick  * External virtual filesystem routines
2237488Smckusick  */
2337488Smckusick 
2437488Smckusick #include "param.h"
2537488Smckusick #include "mount.h"
2637488Smckusick #include "time.h"
2737488Smckusick #include "vnode.h"
2837488Smckusick #include "errno.h"
2937488Smckusick 
3037488Smckusick /*
3137488Smckusick  * Add a new mount point to the list of mounted filesystems.
3237488Smckusick  * Lock the filesystem so that namei will not cross into the
3337488Smckusick  * the tree below the covered vnode.
3437488Smckusick  */
3537488Smckusick vfs_add(mountedvp, mp, flags)
3637488Smckusick 	register struct vnode *mountedvp;
3737488Smckusick 	register struct mount *mp;
3837488Smckusick 	int flags;
3937488Smckusick {
4037488Smckusick 	register int error;
4137488Smckusick 
4237488Smckusick 	error = vfs_lock(mp);
4337488Smckusick 	if (error)
4437488Smckusick 		return (error);
4537488Smckusick 	if (mountedvp == (struct vnode *)0) {
4637488Smckusick 		/*
4737488Smckusick 		 * We are mounting the root filesystem.
4837488Smckusick 		 */
4937488Smckusick 		rootfs = mp;
5037488Smckusick 		mp->m_next = mp;
5137488Smckusick 		mp->m_prev = mp;
5237488Smckusick 	} else {
5337488Smckusick 		if (mountedvp->v_mountedhere != (struct mount *)0) {
5437488Smckusick 			vfs_unlock(mp);
5537488Smckusick 			return(EBUSY);
5637488Smckusick 		}
5737488Smckusick 		/*
5837488Smckusick 		 * Put the new filesystem on the mount list after root.
5937488Smckusick 		 */
6037488Smckusick 		mp->m_next = rootfs->m_next;
6137488Smckusick 		mp->m_prev = rootfs;
6237488Smckusick 		rootfs->m_next = mp;
6337488Smckusick 		mp->m_next->m_prev = mp;
6437488Smckusick 		mountedvp->v_mountedhere = mp;
6537488Smckusick 	}
6637488Smckusick 	mp->m_vnodecovered = mountedvp;
6737488Smckusick 	if (flags & M_RDONLY) {
6837488Smckusick 		mp->m_flag |= M_RDONLY;
6937488Smckusick 	} else {
7037488Smckusick 		mp->m_flag &= ~M_RDONLY;
7137488Smckusick 	}
7237488Smckusick 	if (flags & M_NOSUID) {
7337488Smckusick 		mp->m_flag |= M_NOSUID;
7437488Smckusick 	} else {
7537488Smckusick 		mp->m_flag &= ~M_NOSUID;
7637488Smckusick 	}
7737488Smckusick 	return (0);
7837488Smckusick }
7937488Smckusick 
8037488Smckusick /*
8137488Smckusick  * Remove a mount point from the list of mounted filesystems.
8237488Smckusick  * Unmount of the root is illegal.
8337488Smckusick  */
8437488Smckusick void
8537488Smckusick vfs_remove(mp)
8637488Smckusick 	register struct mount *mp;
8737488Smckusick {
8837488Smckusick 
8937488Smckusick 	if (mp == rootfs)
9037488Smckusick 		panic("vfs_remove: unmounting root");
9137488Smckusick 	mp->m_prev->m_next = mp->m_next;
9237488Smckusick 	mp->m_next->m_prev = mp->m_prev;
9337488Smckusick 	mp->m_vnodecovered->v_mountedhere = (struct mount *)0;
9437488Smckusick 	vfs_unlock(mp);
9537488Smckusick }
9637488Smckusick 
9737488Smckusick /*
9837488Smckusick  * Lock a filesystem.
9937488Smckusick  * Used to prevent access to it while mounting and unmounting.
10037488Smckusick  */
10137488Smckusick vfs_lock(mp)
10237488Smckusick 	register struct mount *mp;
10337488Smckusick {
10437488Smckusick 
10537488Smckusick 	if (mp->m_flag & M_MLOCK)
10637488Smckusick 		return (EBUSY);
10737488Smckusick 	mp->m_flag |= M_MLOCK;
10837488Smckusick 	return (0);
10937488Smckusick }
11037488Smckusick 
11137488Smckusick /*
11237488Smckusick  * Unlock a locked filesystem.
11337488Smckusick  * Panic if filesystem is not locked.
11437488Smckusick  */
11537488Smckusick void
11637488Smckusick vfs_unlock(mp)
11737488Smckusick 	register struct mount *mp;
11837488Smckusick {
11937488Smckusick 
12037488Smckusick 	if ((mp->m_flag & M_MLOCK) == 0)
12137488Smckusick 		panic("vfs_unlock: locked fs");
12237488Smckusick 	mp->m_flag &= ~M_MLOCK;
12337488Smckusick 	if (mp->m_flag & M_MWAIT) {
12437488Smckusick 		mp->m_flag &= ~M_MWAIT;
12537488Smckusick 		wakeup((caddr_t)mp);
12637488Smckusick 	}
12737488Smckusick }
12837488Smckusick 
12937488Smckusick /*
13037488Smckusick  * Lookup a mount point by filesystem identifier.
13137488Smckusick  */
13237488Smckusick struct mount *
13337488Smckusick getvfs(fsid)
13437488Smckusick 	fsid_t *fsid;
13537488Smckusick {
13637488Smckusick 	register struct mount *mp;
13737488Smckusick 
13837488Smckusick 	for (mp = rootfs; mp; mp = mp->m_next) {
13937488Smckusick 		if (mp->m_fsid.val[0] == fsid->val[0] &&
14037488Smckusick 		    mp->m_fsid.val[1] == fsid->val[1]) {
14137488Smckusick 			break;
14237488Smckusick 		}
14337488Smckusick 	}
14437488Smckusick 	return (mp);
14537488Smckusick }
14637488Smckusick 
14737488Smckusick /*
14837488Smckusick  * Set vnode attributes to VNOVAL
14937488Smckusick  */
15037488Smckusick void vattr_null(vap)
15137488Smckusick 	register struct vattr *vap;
15237488Smckusick {
15337488Smckusick 
15437488Smckusick 	vap->va_type = VNON;
15537488Smckusick 	vap->va_mode = vap->va_nlink = vap->va_uid = vap->va_gid =
15637488Smckusick 		vap->va_fsid = vap->va_fileid = vap->va_size =
15737488Smckusick 		vap->va_size1 = vap->va_blocksize = vap->va_rdev =
15837488Smckusick 		vap->va_bytes = vap->va_bytes1 =
15937488Smckusick 		vap->va_atime.tv_sec = vap->va_atime.tv_usec =
16037488Smckusick 		vap->va_mtime.tv_sec = vap->va_mtime.tv_usec =
161*38258Smckusick 		vap->va_ctime.tv_sec = vap->va_ctime.tv_usec =
162*38258Smckusick 		vap->va_flags = vap->va_gen = VNOVAL;
16337488Smckusick }
164