null_vfsops.c revision 128019
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 128019 2004-04-07 20:46:16Z imp $ 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/kernel.h> 46#include <sys/lock.h> 47#include <sys/malloc.h> 48#include <sys/mount.h> 49#include <sys/namei.h> 50#include <sys/proc.h> 51#include <sys/vnode.h> 52 53#include <fs/nullfs/null.h> 54 55static MALLOC_DEFINE(M_NULLFSMNT, "NULLFS mount", "NULLFS mount structure"); 56 57static vfs_fhtovp_t nullfs_fhtovp; 58static vfs_checkexp_t nullfs_checkexp; 59static vfs_nmount_t nullfs_mount; 60static vfs_quotactl_t nullfs_quotactl; 61static vfs_root_t nullfs_root; 62static vfs_start_t nullfs_start; 63static vfs_sync_t nullfs_sync; 64static vfs_statfs_t nullfs_statfs; 65static vfs_unmount_t nullfs_unmount; 66static vfs_vget_t nullfs_vget; 67static vfs_vptofh_t nullfs_vptofh; 68static vfs_extattrctl_t nullfs_extattrctl; 69 70/* 71 * Mount null layer 72 */ 73static int 74nullfs_mount(mp, ndp, td) 75 struct mount *mp; 76 struct nameidata *ndp; 77 struct thread *td; 78{ 79 int error = 0; 80 struct vnode *lowerrootvp, *vp; 81 struct vnode *nullm_rootvp; 82 struct null_mount *xmp; 83 char *target; 84 size_t size; 85 int isvnunlocked = 0, len; 86 87 NULLFSDEBUG("nullfs_mount(mp = %p)\n", (void *)mp); 88 89 /* 90 * Update is a no-op 91 */ 92 if (mp->mnt_flag & MNT_UPDATE) { 93 return (EOPNOTSUPP); 94 /* return VFS_MOUNT(MOUNTTONULLMOUNT(mp)->nullm_vfs, path, data, ndp, td);*/ 95 } 96 97 /* 98 * Get argument 99 */ 100 error = vfs_getopt(mp->mnt_optnew, "target", (void **)&target, &len); 101 if (error || target[len - 1] != '\0') 102 return (EINVAL); 103 104 /* 105 * Unlock lower node to avoid deadlock. 106 * (XXX) VOP_ISLOCKED is needed? 107 */ 108 if ((mp->mnt_vnodecovered->v_op == null_vnodeop_p) && 109 VOP_ISLOCKED(mp->mnt_vnodecovered, NULL)) { 110 VOP_UNLOCK(mp->mnt_vnodecovered, 0, td); 111 isvnunlocked = 1; 112 } 113 /* 114 * Find lower node 115 */ 116 NDINIT(ndp, LOOKUP, FOLLOW|WANTPARENT|LOCKLEAF, 117 UIO_SYSSPACE, target, td); 118 error = namei(ndp); 119 /* 120 * Re-lock vnode. 121 */ 122 if (isvnunlocked && !VOP_ISLOCKED(mp->mnt_vnodecovered, NULL)) 123 vn_lock(mp->mnt_vnodecovered, LK_EXCLUSIVE | LK_RETRY, td); 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 vrele(ndp->ni_dvp); 135 ndp->ni_dvp = NULLVP; 136 137 /* 138 * Check multi null mount to avoid `lock against myself' panic. 139 */ 140 if (lowerrootvp == VTONULL(mp->mnt_vnodecovered)->null_lowervp) { 141 NULLFSDEBUG("nullfs_mount: multi null mount?\n"); 142 vput(lowerrootvp); 143 return (EDEADLK); 144 } 145 146 xmp = (struct null_mount *) malloc(sizeof(struct null_mount), 147 M_NULLFSMNT, M_WAITOK); /* XXX */ 148 149 /* 150 * Save reference to underlying FS 151 */ 152 xmp->nullm_vfs = lowerrootvp->v_mount; 153 154 /* 155 * Save reference. Each mount also holds 156 * a reference on the root vnode. 157 */ 158 error = null_nodeget(mp, lowerrootvp, &vp); 159 /* 160 * Make sure the node alias worked 161 */ 162 if (error) { 163 VOP_UNLOCK(vp, 0, td); 164 vrele(lowerrootvp); 165 free(xmp, M_NULLFSMNT); /* XXX */ 166 return (error); 167 } 168 169 /* 170 * Keep a held reference to the root vnode. 171 * It is vrele'd in nullfs_unmount. 172 */ 173 nullm_rootvp = vp; 174 nullm_rootvp->v_vflag |= VV_ROOT; 175 xmp->nullm_rootvp = nullm_rootvp; 176 177 /* 178 * Unlock the node (either the lower or the alias) 179 */ 180 VOP_UNLOCK(vp, 0, td); 181 182 if (NULLVPTOLOWERVP(nullm_rootvp)->v_mount->mnt_flag & MNT_LOCAL) 183 mp->mnt_flag |= MNT_LOCAL; 184 mp->mnt_data = (qaddr_t) xmp; 185 vfs_getnewfsid(mp); 186 187 (void) copystr(target, mp->mnt_stat.f_mntfromname, 188 MNAMELEN - 1, &size); 189 bzero(mp->mnt_stat.f_mntfromname + size, MNAMELEN - size); 190 (void)nullfs_statfs(mp, &mp->mnt_stat, td); 191 NULLFSDEBUG("nullfs_mount: lower %s, alias at %s\n", 192 mp->mnt_stat.f_mntfromname, mp->mnt_stat.f_mntonname); 193 return (0); 194} 195 196/* 197 * VFS start. Nothing needed here - the start routine 198 * on the underlying filesystem will have been called 199 * when that filesystem was mounted. 200 */ 201static int 202nullfs_start(mp, flags, td) 203 struct mount *mp; 204 int flags; 205 struct thread *td; 206{ 207 return (0); 208 /* return VFS_START(MOUNTTONULLMOUNT(mp)->nullm_vfs, flags, td); */ 209} 210 211/* 212 * Free reference to null layer 213 */ 214static int 215nullfs_unmount(mp, mntflags, td) 216 struct mount *mp; 217 int mntflags; 218 struct thread *td; 219{ 220 void *mntdata; 221 int error; 222 int flags = 0; 223 224 NULLFSDEBUG("nullfs_unmount: mp = %p\n", (void *)mp); 225 226 if (mntflags & MNT_FORCE) 227 flags |= FORCECLOSE; 228 229 /* There is 1 extra root vnode reference (nullm_rootvp). */ 230 error = vflush(mp, 1, flags); 231 if (error) 232 return (error); 233 234 /* 235 * Finally, throw away the null_mount structure 236 */ 237 mntdata = mp->mnt_data; 238 mp->mnt_data = 0; 239 free(mntdata, M_NULLFSMNT); 240 return 0; 241} 242 243static int 244nullfs_root(mp, vpp) 245 struct mount *mp; 246 struct vnode **vpp; 247{ 248 struct thread *td = curthread; /* XXX */ 249 struct vnode *vp; 250 251 NULLFSDEBUG("nullfs_root(mp = %p, vp = %p->%p)\n", (void *)mp, 252 (void *)MOUNTTONULLMOUNT(mp)->nullm_rootvp, 253 (void *)NULLVPTOLOWERVP(MOUNTTONULLMOUNT(mp)->nullm_rootvp)); 254 255 /* 256 * Return locked reference to root. 257 */ 258 vp = MOUNTTONULLMOUNT(mp)->nullm_rootvp; 259 VREF(vp); 260 261#ifdef NULLFS_DEBUG 262 if (VOP_ISLOCKED(vp, NULL)) { 263 Debugger("root vnode is locked.\n"); 264 vrele(vp); 265 return (EDEADLK); 266 } 267#endif 268 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, td); 269 *vpp = vp; 270 return 0; 271} 272 273static int 274nullfs_quotactl(mp, cmd, uid, arg, td) 275 struct mount *mp; 276 int cmd; 277 uid_t uid; 278 caddr_t arg; 279 struct thread *td; 280{ 281 return VFS_QUOTACTL(MOUNTTONULLMOUNT(mp)->nullm_vfs, cmd, uid, arg, td); 282} 283 284static int 285nullfs_statfs(mp, sbp, td) 286 struct mount *mp; 287 struct statfs *sbp; 288 struct thread *td; 289{ 290 int error; 291 struct statfs mstat; 292 293 NULLFSDEBUG("nullfs_statfs(mp = %p, vp = %p->%p)\n", (void *)mp, 294 (void *)MOUNTTONULLMOUNT(mp)->nullm_rootvp, 295 (void *)NULLVPTOLOWERVP(MOUNTTONULLMOUNT(mp)->nullm_rootvp)); 296 297 bzero(&mstat, sizeof(mstat)); 298 299 error = VFS_STATFS(MOUNTTONULLMOUNT(mp)->nullm_vfs, &mstat, td); 300 if (error) 301 return (error); 302 303 /* now copy across the "interesting" information and fake the rest */ 304 sbp->f_type = mstat.f_type; 305 sbp->f_flags = mstat.f_flags; 306 sbp->f_bsize = mstat.f_bsize; 307 sbp->f_iosize = mstat.f_iosize; 308 sbp->f_blocks = mstat.f_blocks; 309 sbp->f_bfree = mstat.f_bfree; 310 sbp->f_bavail = mstat.f_bavail; 311 sbp->f_files = mstat.f_files; 312 sbp->f_ffree = mstat.f_ffree; 313 if (sbp != &mp->mnt_stat) { 314 bcopy(&mp->mnt_stat.f_fsid, &sbp->f_fsid, sizeof(sbp->f_fsid)); 315 bcopy(mp->mnt_stat.f_mntonname, sbp->f_mntonname, MNAMELEN); 316 bcopy(mp->mnt_stat.f_mntfromname, sbp->f_mntfromname, MNAMELEN); 317 } 318 return (0); 319} 320 321static int 322nullfs_sync(mp, waitfor, cred, td) 323 struct mount *mp; 324 int waitfor; 325 struct ucred *cred; 326 struct thread *td; 327{ 328 /* 329 * XXX - Assumes no data cached at null layer. 330 */ 331 return (0); 332} 333 334static int 335nullfs_vget(mp, ino, flags, vpp) 336 struct mount *mp; 337 ino_t ino; 338 int flags; 339 struct vnode **vpp; 340{ 341 int error; 342 error = VFS_VGET(MOUNTTONULLMOUNT(mp)->nullm_vfs, ino, flags, vpp); 343 if (error) 344 return (error); 345 346 return (null_nodeget(mp, *vpp, vpp)); 347} 348 349static int 350nullfs_fhtovp(mp, fidp, vpp) 351 struct mount *mp; 352 struct fid *fidp; 353 struct vnode **vpp; 354{ 355 int error; 356 error = VFS_FHTOVP(MOUNTTONULLMOUNT(mp)->nullm_vfs, fidp, vpp); 357 if (error) 358 return (error); 359 360 return (null_nodeget(mp, *vpp, vpp)); 361} 362 363static int 364nullfs_checkexp(mp, nam, extflagsp, credanonp) 365 struct mount *mp; 366 struct sockaddr *nam; 367 int *extflagsp; 368 struct ucred **credanonp; 369{ 370 371 return VFS_CHECKEXP(MOUNTTONULLMOUNT(mp)->nullm_vfs, nam, 372 extflagsp, credanonp); 373} 374 375static int 376nullfs_vptofh(vp, fhp) 377 struct vnode *vp; 378 struct fid *fhp; 379{ 380 struct vnode *lvp; 381 382 lvp = NULLVPTOLOWERVP(vp); 383 return VFS_VPTOFH(lvp, fhp); 384} 385 386static int 387nullfs_extattrctl(mp, cmd, filename_vp, namespace, attrname, td) 388 struct mount *mp; 389 int cmd; 390 struct vnode *filename_vp; 391 int namespace; 392 const char *attrname; 393 struct thread *td; 394{ 395 return VFS_EXTATTRCTL(MOUNTTONULLMOUNT(mp)->nullm_vfs, cmd, filename_vp, 396 namespace, attrname, td); 397} 398 399 400static struct vfsops null_vfsops = { 401 .vfs_checkexp = nullfs_checkexp, 402 .vfs_extattrctl = nullfs_extattrctl, 403 .vfs_fhtovp = nullfs_fhtovp, 404 .vfs_init = nullfs_init, 405 .vfs_nmount = nullfs_mount, 406 .vfs_quotactl = nullfs_quotactl, 407 .vfs_root = nullfs_root, 408 .vfs_start = nullfs_start, 409 .vfs_statfs = nullfs_statfs, 410 .vfs_sync = nullfs_sync, 411 .vfs_uninit = nullfs_uninit, 412 .vfs_unmount = nullfs_unmount, 413 .vfs_vget = nullfs_vget, 414 .vfs_vptofh = nullfs_vptofh, 415}; 416 417VFS_SET(null_vfsops, nullfs, VFCF_LOOPBACK); 418