| 1 | /* |
| 2 | * Copyright (c) 1989 The Regents of the University of California. |
| 3 | * All rights reserved. |
| 4 | * |
| 5 | * Redistribution and use in source and binary forms are permitted |
| 6 | * provided that the above copyright notice and this paragraph are |
| 7 | * duplicated in all such forms and that any documentation, |
| 8 | * advertising materials, and other materials related to such |
| 9 | * distribution and use acknowledge that the software was developed |
| 10 | * by the University of California, Berkeley. The name of the |
| 11 | * University may not be used to endorse or promote products derived |
| 12 | * from this software without specific prior written permission. |
| 13 | * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR |
| 14 | * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED |
| 15 | * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. |
| 16 | * |
| 17 | * @(#)vfs_subr.c 7.1 (Berkeley) %G% |
| 18 | */ |
| 19 | |
| 20 | /* |
| 21 | * External virtual filesystem routines |
| 22 | */ |
| 23 | |
| 24 | #include "param.h" |
| 25 | #include "mount.h" |
| 26 | #include "time.h" |
| 27 | #include "vnode.h" |
| 28 | #include "errno.h" |
| 29 | |
| 30 | /* |
| 31 | * Add a new mount point to the list of mounted filesystems. |
| 32 | * Lock the filesystem so that namei will not cross into the |
| 33 | * the tree below the covered vnode. |
| 34 | */ |
| 35 | vfs_add(mountedvp, mp, flags) |
| 36 | register struct vnode *mountedvp; |
| 37 | register struct mount *mp; |
| 38 | int flags; |
| 39 | { |
| 40 | register int error; |
| 41 | |
| 42 | error = vfs_lock(mp); |
| 43 | if (error) |
| 44 | return (error); |
| 45 | if (mountedvp == (struct vnode *)0) { |
| 46 | /* |
| 47 | * We are mounting the root filesystem. |
| 48 | */ |
| 49 | rootfs = mp; |
| 50 | mp->m_next = mp; |
| 51 | mp->m_prev = mp; |
| 52 | } else { |
| 53 | if (mountedvp->v_mountedhere != (struct mount *)0) { |
| 54 | vfs_unlock(mp); |
| 55 | return(EBUSY); |
| 56 | } |
| 57 | /* |
| 58 | * Put the new filesystem on the mount list after root. |
| 59 | */ |
| 60 | mp->m_next = rootfs->m_next; |
| 61 | mp->m_prev = rootfs; |
| 62 | rootfs->m_next = mp; |
| 63 | mp->m_next->m_prev = mp; |
| 64 | mountedvp->v_mountedhere = mp; |
| 65 | } |
| 66 | mp->m_vnodecovered = mountedvp; |
| 67 | if (flags & M_RDONLY) { |
| 68 | mp->m_flag |= M_RDONLY; |
| 69 | } else { |
| 70 | mp->m_flag &= ~M_RDONLY; |
| 71 | } |
| 72 | if (flags & M_NOSUID) { |
| 73 | mp->m_flag |= M_NOSUID; |
| 74 | } else { |
| 75 | mp->m_flag &= ~M_NOSUID; |
| 76 | } |
| 77 | return (0); |
| 78 | } |
| 79 | |
| 80 | /* |
| 81 | * Remove a mount point from the list of mounted filesystems. |
| 82 | * Unmount of the root is illegal. |
| 83 | */ |
| 84 | void |
| 85 | vfs_remove(mp) |
| 86 | register struct mount *mp; |
| 87 | { |
| 88 | |
| 89 | if (mp == rootfs) |
| 90 | panic("vfs_remove: unmounting root"); |
| 91 | mp->m_prev->m_next = mp->m_next; |
| 92 | mp->m_next->m_prev = mp->m_prev; |
| 93 | mp->m_vnodecovered->v_mountedhere = (struct mount *)0; |
| 94 | vfs_unlock(mp); |
| 95 | } |
| 96 | |
| 97 | /* |
| 98 | * Lock a filesystem. |
| 99 | * Used to prevent access to it while mounting and unmounting. |
| 100 | */ |
| 101 | vfs_lock(mp) |
| 102 | register struct mount *mp; |
| 103 | { |
| 104 | |
| 105 | if (mp->m_flag & M_MLOCK) |
| 106 | return (EBUSY); |
| 107 | mp->m_flag |= M_MLOCK; |
| 108 | return (0); |
| 109 | } |
| 110 | |
| 111 | /* |
| 112 | * Unlock a locked filesystem. |
| 113 | * Panic if filesystem is not locked. |
| 114 | */ |
| 115 | void |
| 116 | vfs_unlock(mp) |
| 117 | register struct mount *mp; |
| 118 | { |
| 119 | |
| 120 | if ((mp->m_flag & M_MLOCK) == 0) |
| 121 | panic("vfs_unlock: locked fs"); |
| 122 | mp->m_flag &= ~M_MLOCK; |
| 123 | if (mp->m_flag & M_MWAIT) { |
| 124 | mp->m_flag &= ~M_MWAIT; |
| 125 | wakeup((caddr_t)mp); |
| 126 | } |
| 127 | } |
| 128 | |
| 129 | /* |
| 130 | * Lookup a mount point by filesystem identifier. |
| 131 | */ |
| 132 | struct mount * |
| 133 | getvfs(fsid) |
| 134 | fsid_t *fsid; |
| 135 | { |
| 136 | register struct mount *mp; |
| 137 | |
| 138 | for (mp = rootfs; mp; mp = mp->m_next) { |
| 139 | if (mp->m_fsid.val[0] == fsid->val[0] && |
| 140 | mp->m_fsid.val[1] == fsid->val[1]) { |
| 141 | break; |
| 142 | } |
| 143 | } |
| 144 | return (mp); |
| 145 | } |
| 146 | |
| 147 | /* |
| 148 | * Set vnode attributes to VNOVAL |
| 149 | */ |
| 150 | void vattr_null(vap) |
| 151 | register struct vattr *vap; |
| 152 | { |
| 153 | |
| 154 | vap->va_type = VNON; |
| 155 | vap->va_mode = vap->va_nlink = vap->va_uid = vap->va_gid = |
| 156 | vap->va_fsid = vap->va_fileid = vap->va_size = |
| 157 | vap->va_size1 = vap->va_blocksize = vap->va_rdev = |
| 158 | vap->va_bytes = vap->va_bytes1 = |
| 159 | vap->va_atime.tv_sec = vap->va_atime.tv_usec = |
| 160 | vap->va_mtime.tv_sec = vap->va_mtime.tv_usec = |
| 161 | vap->va_ctime.tv_sec = vap->va_ctime.tv_usec = VNOVAL; |
| 162 | } |