null_vfsops.c revision 231269
1/*- 2 * Copyright (c) 1992, 1993, 1995 3 * The Regents of the University of California. All rights reserved. 4 * 5 * This code is derived from software donated to Berkeley by 6 * Jan-Simon Pendry. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 4. Neither the name of the University nor the names of its contributors 17 * may be used to endorse or promote products derived from this software 18 * without specific prior written permission. 19 * 20 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30 * SUCH DAMAGE. 31 * 32 * @(#)null_vfsops.c 8.2 (Berkeley) 1/21/94 33 * 34 * @(#)lofs_vfsops.c 1.2 (Berkeley) 6/18/92 35 * $FreeBSD: head/sys/fs/nullfs/null_vfsops.c 231269 2012-02-09 10:39:01Z mm $ 36 */ 37 38/* 39 * Null Layer 40 * (See null_vnops.c for a description of what this does.) 41 */ 42 43#include <sys/param.h> 44#include <sys/systm.h> 45#include <sys/fcntl.h> 46#include <sys/kernel.h> 47#include <sys/lock.h> 48#include <sys/malloc.h> 49#include <sys/mount.h> 50#include <sys/namei.h> 51#include <sys/proc.h> 52#include <sys/vnode.h> 53 54#include <fs/nullfs/null.h> 55 56static MALLOC_DEFINE(M_NULLFSMNT, "nullfs_mount", "NULLFS mount structure"); 57 58static vfs_fhtovp_t nullfs_fhtovp; 59static vfs_mount_t nullfs_mount; 60static vfs_quotactl_t nullfs_quotactl; 61static vfs_root_t nullfs_root; 62static vfs_sync_t nullfs_sync; 63static vfs_statfs_t nullfs_statfs; 64static vfs_unmount_t nullfs_unmount; 65static vfs_vget_t nullfs_vget; 66static vfs_extattrctl_t nullfs_extattrctl; 67 68/* 69 * Mount null layer 70 */ 71static int 72nullfs_mount(struct mount *mp) 73{ 74 int error = 0; 75 struct vnode *lowerrootvp, *vp; 76 struct vnode *nullm_rootvp; 77 struct null_mount *xmp; 78 char *target; 79 int isvnunlocked = 0, len; 80 struct nameidata nd, *ndp = &nd; 81 82 NULLFSDEBUG("nullfs_mount(mp = %p)\n", (void *)mp); 83 84 if (mp->mnt_flag & MNT_ROOTFS) 85 return (EOPNOTSUPP); 86 /* 87 * Update is a no-op 88 */ 89 if (mp->mnt_flag & MNT_UPDATE) { 90 /* 91 * Only support update mounts for NFS export. 92 */ 93 if (vfs_flagopt(mp->mnt_optnew, "export", NULL, 0)) 94 return (0); 95 else 96 return (EOPNOTSUPP); 97 } 98 99 /* 100 * Get argument 101 */ 102 error = vfs_getopt(mp->mnt_optnew, "target", (void **)&target, &len); 103 if (error || target[len - 1] != '\0') 104 return (EINVAL); 105 106 /* 107 * Unlock lower node to avoid possible deadlock. 108 */ 109 if ((mp->mnt_vnodecovered->v_op == &null_vnodeops) && 110 VOP_ISLOCKED(mp->mnt_vnodecovered) == LK_EXCLUSIVE) { 111 VOP_UNLOCK(mp->mnt_vnodecovered, 0); 112 isvnunlocked = 1; 113 } 114 /* 115 * Find lower node 116 */ 117 NDINIT(ndp, LOOKUP, FOLLOW|LOCKLEAF, UIO_SYSSPACE, target, curthread); 118 error = namei(ndp); 119 /* 120 * Re-lock vnode. 121 */ 122 if (isvnunlocked) 123 vn_lock(mp->mnt_vnodecovered, LK_EXCLUSIVE | LK_RETRY); 124 125 if (error) 126 return (error); 127 NDFREE(ndp, NDF_ONLY_PNBUF); 128 129 /* 130 * Sanity check on lower vnode 131 */ 132 lowerrootvp = ndp->ni_vp; 133 134 /* 135 * Check multi null mount to avoid `lock against myself' panic. 136 */ 137 if (lowerrootvp == VTONULL(mp->mnt_vnodecovered)->null_lowervp) { 138 NULLFSDEBUG("nullfs_mount: multi null mount?\n"); 139 vput(lowerrootvp); 140 return (EDEADLK); 141 } 142 143 xmp = (struct null_mount *) malloc(sizeof(struct null_mount), 144 M_NULLFSMNT, M_WAITOK); /* XXX */ 145 146 /* 147 * Save reference to underlying FS 148 */ 149 xmp->nullm_vfs = lowerrootvp->v_mount; 150 151 /* 152 * Save reference. Each mount also holds 153 * a reference on the root vnode. 154 */ 155 error = null_nodeget(mp, lowerrootvp, &vp); 156 /* 157 * Make sure the node alias worked 158 */ 159 if (error) { 160 free(xmp, M_NULLFSMNT); 161 return (error); 162 } 163 164 /* 165 * Keep a held reference to the root vnode. 166 * It is vrele'd in nullfs_unmount. 167 */ 168 nullm_rootvp = vp; 169 nullm_rootvp->v_vflag |= VV_ROOT; 170 xmp->nullm_rootvp = nullm_rootvp; 171 172 /* 173 * Unlock the node (either the lower or the alias) 174 */ 175 VOP_UNLOCK(vp, 0); 176 177 if (NULLVPTOLOWERVP(nullm_rootvp)->v_mount->mnt_flag & MNT_LOCAL) { 178 MNT_ILOCK(mp); 179 mp->mnt_flag |= MNT_LOCAL; 180 MNT_IUNLOCK(mp); 181 } 182 MNT_ILOCK(mp); 183 mp->mnt_kern_flag |= lowerrootvp->v_mount->mnt_kern_flag & MNTK_MPSAFE; 184 MNT_IUNLOCK(mp); 185 mp->mnt_data = xmp; 186 vfs_getnewfsid(mp); 187 188 vfs_mountedfrom(mp, target); 189 190 NULLFSDEBUG("nullfs_mount: lower %s, alias at %s\n", 191 mp->mnt_stat.f_mntfromname, mp->mnt_stat.f_mntonname); 192 return (0); 193} 194 195/* 196 * Free reference to null layer 197 */ 198static int 199nullfs_unmount(mp, mntflags) 200 struct mount *mp; 201 int mntflags; 202{ 203 void *mntdata; 204 int error; 205 int flags = 0; 206 207 NULLFSDEBUG("nullfs_unmount: mp = %p\n", (void *)mp); 208 209 if (mntflags & MNT_FORCE) 210 flags |= FORCECLOSE; 211 212 /* There is 1 extra root vnode reference (nullm_rootvp). */ 213 error = vflush(mp, 1, flags, curthread); 214 if (error) 215 return (error); 216 217 /* 218 * Finally, throw away the null_mount structure 219 */ 220 mntdata = mp->mnt_data; 221 mp->mnt_data = 0; 222 free(mntdata, M_NULLFSMNT); 223 return 0; 224} 225 226static int 227nullfs_root(mp, flags, vpp) 228 struct mount *mp; 229 int flags; 230 struct vnode **vpp; 231{ 232 struct vnode *vp; 233 234 NULLFSDEBUG("nullfs_root(mp = %p, vp = %p->%p)\n", (void *)mp, 235 (void *)MOUNTTONULLMOUNT(mp)->nullm_rootvp, 236 (void *)NULLVPTOLOWERVP(MOUNTTONULLMOUNT(mp)->nullm_rootvp)); 237 238 /* 239 * Return locked reference to root. 240 */ 241 vp = MOUNTTONULLMOUNT(mp)->nullm_rootvp; 242 VREF(vp); 243 244 ASSERT_VOP_UNLOCKED(vp, "root vnode is locked"); 245 vn_lock(vp, flags | LK_RETRY); 246 *vpp = vp; 247 return 0; 248} 249 250static int 251nullfs_quotactl(mp, cmd, uid, arg) 252 struct mount *mp; 253 int cmd; 254 uid_t uid; 255 void *arg; 256{ 257 return VFS_QUOTACTL(MOUNTTONULLMOUNT(mp)->nullm_vfs, cmd, uid, arg); 258} 259 260static int 261nullfs_statfs(mp, sbp) 262 struct mount *mp; 263 struct statfs *sbp; 264{ 265 int error; 266 struct statfs mstat; 267 268 NULLFSDEBUG("nullfs_statfs(mp = %p, vp = %p->%p)\n", (void *)mp, 269 (void *)MOUNTTONULLMOUNT(mp)->nullm_rootvp, 270 (void *)NULLVPTOLOWERVP(MOUNTTONULLMOUNT(mp)->nullm_rootvp)); 271 272 bzero(&mstat, sizeof(mstat)); 273 274 error = VFS_STATFS(MOUNTTONULLMOUNT(mp)->nullm_vfs, &mstat); 275 if (error) 276 return (error); 277 278 /* now copy across the "interesting" information and fake the rest */ 279 sbp->f_type = mstat.f_type; 280 sbp->f_flags = mstat.f_flags; 281 sbp->f_bsize = mstat.f_bsize; 282 sbp->f_iosize = mstat.f_iosize; 283 sbp->f_blocks = mstat.f_blocks; 284 sbp->f_bfree = mstat.f_bfree; 285 sbp->f_bavail = mstat.f_bavail; 286 sbp->f_files = mstat.f_files; 287 sbp->f_ffree = mstat.f_ffree; 288 return (0); 289} 290 291static int 292nullfs_sync(mp, waitfor) 293 struct mount *mp; 294 int waitfor; 295{ 296 /* 297 * XXX - Assumes no data cached at null layer. 298 */ 299 return (0); 300} 301 302static int 303nullfs_vget(mp, ino, flags, vpp) 304 struct mount *mp; 305 ino_t ino; 306 int flags; 307 struct vnode **vpp; 308{ 309 int error; 310 error = VFS_VGET(MOUNTTONULLMOUNT(mp)->nullm_vfs, ino, flags, vpp); 311 if (error) 312 return (error); 313 314 return (null_nodeget(mp, *vpp, vpp)); 315} 316 317static int 318nullfs_fhtovp(mp, fidp, flags, vpp) 319 struct mount *mp; 320 struct fid *fidp; 321 int flags; 322 struct vnode **vpp; 323{ 324 int error; 325 error = VFS_FHTOVP(MOUNTTONULLMOUNT(mp)->nullm_vfs, fidp, LK_EXCLUSIVE, 326 vpp); 327 if (error) 328 return (error); 329 330 return (null_nodeget(mp, *vpp, vpp)); 331} 332 333static int 334nullfs_extattrctl(mp, cmd, filename_vp, namespace, attrname) 335 struct mount *mp; 336 int cmd; 337 struct vnode *filename_vp; 338 int namespace; 339 const char *attrname; 340{ 341 return VFS_EXTATTRCTL(MOUNTTONULLMOUNT(mp)->nullm_vfs, cmd, filename_vp, 342 namespace, attrname); 343} 344 345 346static struct vfsops null_vfsops = { 347 .vfs_extattrctl = nullfs_extattrctl, 348 .vfs_fhtovp = nullfs_fhtovp, 349 .vfs_init = nullfs_init, 350 .vfs_mount = nullfs_mount, 351 .vfs_quotactl = nullfs_quotactl, 352 .vfs_root = nullfs_root, 353 .vfs_statfs = nullfs_statfs, 354 .vfs_sync = nullfs_sync, 355 .vfs_uninit = nullfs_uninit, 356 .vfs_unmount = nullfs_unmount, 357 .vfs_vget = nullfs_vget, 358}; 359 360VFS_SET(null_vfsops, nullfs, VFCF_LOOPBACK | VFCF_JAIL); 361