null_vfsops.c revision 28270
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 * 3. All advertising materials mentioning features or use of this software 17 * must display the following acknowledgement: 18 * This product includes software developed by the University of 19 * California, Berkeley and its contributors. 20 * 4. Neither the name of the University nor the names of its contributors 21 * may be used to endorse or promote products derived from this software 22 * without specific prior written permission. 23 * 24 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 25 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 26 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 27 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 28 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 29 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 30 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 31 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 32 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 33 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 34 * SUCH DAMAGE. 35 * 36 * @(#)null_vfsops.c 8.2 (Berkeley) 1/21/94 37 * 38 * @(#)lofs_vfsops.c 1.2 (Berkeley) 6/18/92 39 * $Id: null_vfsops.c,v 1.18 1997/08/02 14:32:05 bde Exp $ 40 */ 41 42/* 43 * Null Layer 44 * (See null_vnops.c for a description of what this does.) 45 */ 46 47#include <sys/param.h> 48#include <sys/systm.h> 49#include <sys/kernel.h> 50#include <sys/proc.h> 51#include <sys/vnode.h> 52#include <sys/mount.h> 53#include <sys/namei.h> 54#include <sys/malloc.h> 55#include <miscfs/nullfs/null.h> 56 57static int nullfs_fhtovp __P((struct mount *mp, struct fid *fidp, 58 struct sockaddr *nam, struct vnode **vpp, 59 int *exflagsp, struct ucred **credanonp)); 60static int nullfs_mount __P((struct mount *mp, char *path, caddr_t data, 61 struct nameidata *ndp, struct proc *p)); 62static int nullfs_quotactl __P((struct mount *mp, int cmd, uid_t uid, 63 caddr_t arg, struct proc *p)); 64static int nullfs_root __P((struct mount *mp, struct vnode **vpp)); 65static int nullfs_start __P((struct mount *mp, int flags, struct proc *p)); 66static int nullfs_statfs __P((struct mount *mp, struct statfs *sbp, 67 struct proc *p)); 68static int nullfs_sync __P((struct mount *mp, int waitfor, 69 struct ucred *cred, struct proc *p)); 70static int nullfs_unmount __P((struct mount *mp, int mntflags, 71 struct proc *p)); 72static int nullfs_vget __P((struct mount *mp, ino_t ino, 73 struct vnode **vpp)); 74static int nullfs_vptofh __P((struct vnode *vp, struct fid *fhp)); 75 76/* 77 * Mount null layer 78 */ 79static int 80nullfs_mount(mp, path, data, ndp, p) 81 struct mount *mp; 82 char *path; 83 caddr_t data; 84 struct nameidata *ndp; 85 struct proc *p; 86{ 87 int error = 0; 88 struct null_args args; 89 struct vnode *lowerrootvp, *vp; 90 struct vnode *nullm_rootvp; 91 struct null_mount *xmp; 92 u_int size; 93 int isvnunlocked = 0; 94 95#ifdef NULLFS_DIAGNOSTIC 96 printf("nullfs_mount(mp = %x)\n", mp); 97#endif 98 99 /* 100 * Update is a no-op 101 */ 102 if (mp->mnt_flag & MNT_UPDATE) { 103 return (EOPNOTSUPP); 104 /* return VFS_MOUNT(MOUNTTONULLMOUNT(mp)->nullm_vfs, path, data, ndp, p);*/ 105 } 106 107 /* 108 * Get argument 109 */ 110 error = copyin(data, (caddr_t)&args, sizeof(struct null_args)); 111 if (error) 112 return (error); 113 114 /* 115 * Unlock lower node to avoid deadlock. 116 * (XXX) VOP_ISLOCKED is needed? 117 */ 118 if ((mp->mnt_vnodecovered->v_op == null_vnodeop_p) && 119 VOP_ISLOCKED(mp->mnt_vnodecovered)) { 120 VOP_UNLOCK(mp->mnt_vnodecovered, 0, p); 121 isvnunlocked = 1; 122 } 123 /* 124 * Find lower node 125 */ 126 NDINIT(ndp, LOOKUP, FOLLOW|WANTPARENT|LOCKLEAF, 127 UIO_USERSPACE, args.target, p); 128 error = namei(ndp); 129 /* 130 * Re-lock vnode. 131 */ 132 if (isvnunlocked && !VOP_ISLOCKED(mp->mnt_vnodecovered)) 133 vn_lock(mp->mnt_vnodecovered, LK_EXCLUSIVE | LK_RETRY, p); 134 135 if (error) 136 return (error); 137 138 /* 139 * Sanity check on lower vnode 140 */ 141 lowerrootvp = ndp->ni_vp; 142 143 vrele(ndp->ni_dvp); 144 ndp->ni_dvp = NULLVP; 145 146 /* 147 * Check multi null mount to avoid `lock against myself' panic. 148 */ 149 if (lowerrootvp == VTONULL(mp->mnt_vnodecovered)->null_lowervp) { 150#ifdef DIAGNOSTIC 151 printf("nullfs_mount: multi null mount?\n"); 152#endif 153 return (EDEADLK); 154 } 155 156 xmp = (struct null_mount *) malloc(sizeof(struct null_mount), 157 M_UFSMNT, M_WAITOK); /* XXX */ 158 159 /* 160 * Save reference to underlying FS 161 */ 162 xmp->nullm_vfs = lowerrootvp->v_mount; 163 164 /* 165 * Save reference. Each mount also holds 166 * a reference on the root vnode. 167 */ 168 error = null_node_create(mp, lowerrootvp, &vp); 169 /* 170 * Unlock the node (either the lower or the alias) 171 */ 172 VOP_UNLOCK(vp, 0, p); 173 /* 174 * Make sure the node alias worked 175 */ 176 if (error) { 177 vrele(lowerrootvp); 178 free(xmp, M_UFSMNT); /* XXX */ 179 return (error); 180 } 181 182 /* 183 * Keep a held reference to the root vnode. 184 * It is vrele'd in nullfs_unmount. 185 */ 186 nullm_rootvp = vp; 187 nullm_rootvp->v_flag |= VROOT; 188 xmp->nullm_rootvp = nullm_rootvp; 189 if (NULLVPTOLOWERVP(nullm_rootvp)->v_mount->mnt_flag & MNT_LOCAL) 190 mp->mnt_flag |= MNT_LOCAL; 191 mp->mnt_data = (qaddr_t) xmp; 192 vfs_getnewfsid(mp); 193 194 (void) copyinstr(path, mp->mnt_stat.f_mntonname, MNAMELEN - 1, &size); 195 bzero(mp->mnt_stat.f_mntonname + size, MNAMELEN - size); 196 (void) copyinstr(args.target, mp->mnt_stat.f_mntfromname, MNAMELEN - 1, 197 &size); 198 bzero(mp->mnt_stat.f_mntfromname + size, MNAMELEN - size); 199#ifdef NULLFS_DIAGNOSTIC 200 printf("nullfs_mount: lower %s, alias at %s\n", 201 mp->mnt_stat.f_mntfromname, mp->mnt_stat.f_mntonname); 202#endif 203 return (0); 204} 205 206/* 207 * VFS start. Nothing needed here - the start routine 208 * on the underlying filesystem will have been called 209 * when that filesystem was mounted. 210 */ 211static int 212nullfs_start(mp, flags, p) 213 struct mount *mp; 214 int flags; 215 struct proc *p; 216{ 217 return (0); 218 /* return VFS_START(MOUNTTONULLMOUNT(mp)->nullm_vfs, flags, p); */ 219} 220 221/* 222 * Free reference to null layer 223 */ 224static int 225nullfs_unmount(mp, mntflags, p) 226 struct mount *mp; 227 int mntflags; 228 struct proc *p; 229{ 230 struct vnode *nullm_rootvp = MOUNTTONULLMOUNT(mp)->nullm_rootvp; 231 int error; 232 int flags = 0; 233 234#ifdef NULLFS_DIAGNOSTIC 235 printf("nullfs_unmount(mp = %x)\n", mp); 236#endif 237 238 if (mntflags & MNT_FORCE) 239 flags |= FORCECLOSE; 240 241 /* 242 * Clear out buffer cache. I don't think we 243 * ever get anything cached at this level at the 244 * moment, but who knows... 245 */ 246#if 0 247 mntflushbuf(mp, 0); 248 if (mntinvalbuf(mp, 1)) 249 return (EBUSY); 250#endif 251 if (nullm_rootvp->v_usecount > 1) 252 return (EBUSY); 253 error = vflush(mp, nullm_rootvp, flags); 254 if (error) 255 return (error); 256 257#ifdef NULLFS_DIAGNOSTIC 258 vprint("alias root of lower", nullm_rootvp); 259#endif 260 /* 261 * Release reference on underlying root vnode 262 */ 263 vrele(nullm_rootvp); 264 /* 265 * And blow it away for future re-use 266 */ 267 vgone(nullm_rootvp); 268 /* 269 * Finally, throw away the null_mount structure 270 */ 271 free(mp->mnt_data, M_UFSMNT); /* XXX */ 272 mp->mnt_data = 0; 273 return 0; 274} 275 276static int 277nullfs_root(mp, vpp) 278 struct mount *mp; 279 struct vnode **vpp; 280{ 281 struct proc *p = curproc; /* XXX */ 282 struct vnode *vp; 283 284#ifdef NULLFS_DIAGNOSTIC 285 printf("nullfs_root(mp = %x, vp = %x->%x)\n", mp, 286 MOUNTTONULLMOUNT(mp)->nullm_rootvp, 287 NULLVPTOLOWERVP(MOUNTTONULLMOUNT(mp)->nullm_rootvp) 288 ); 289#endif 290 291 /* 292 * Return locked reference to root. 293 */ 294 vp = MOUNTTONULLMOUNT(mp)->nullm_rootvp; 295 VREF(vp); 296 if (VOP_ISLOCKED(vp)) { 297 /* 298 * XXX 299 * Should we check type of node? 300 */ 301#ifdef DIAGNOSTIC 302 printf("nullfs_root: multi null mount?\n"); 303#endif 304 vrele(vp); 305 return (EDEADLK); 306 } else 307 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, p); 308 *vpp = vp; 309 return 0; 310} 311 312static int 313nullfs_quotactl(mp, cmd, uid, arg, p) 314 struct mount *mp; 315 int cmd; 316 uid_t uid; 317 caddr_t arg; 318 struct proc *p; 319{ 320 return VFS_QUOTACTL(MOUNTTONULLMOUNT(mp)->nullm_vfs, cmd, uid, arg, p); 321} 322 323static int 324nullfs_statfs(mp, sbp, p) 325 struct mount *mp; 326 struct statfs *sbp; 327 struct proc *p; 328{ 329 int error; 330 struct statfs mstat; 331 332#ifdef NULLFS_DIAGNOSTIC 333 printf("nullfs_statfs(mp = %x, vp = %x->%x)\n", mp, 334 MOUNTTONULLMOUNT(mp)->nullm_rootvp, 335 NULLVPTOLOWERVP(MOUNTTONULLMOUNT(mp)->nullm_rootvp) 336 ); 337#endif 338 339 bzero(&mstat, sizeof(mstat)); 340 341 error = VFS_STATFS(MOUNTTONULLMOUNT(mp)->nullm_vfs, &mstat, p); 342 if (error) 343 return (error); 344 345 /* now copy across the "interesting" information and fake the rest */ 346 sbp->f_type = mstat.f_type; 347 sbp->f_flags = mstat.f_flags; 348 sbp->f_bsize = mstat.f_bsize; 349 sbp->f_iosize = mstat.f_iosize; 350 sbp->f_blocks = mstat.f_blocks; 351 sbp->f_bfree = mstat.f_bfree; 352 sbp->f_bavail = mstat.f_bavail; 353 sbp->f_files = mstat.f_files; 354 sbp->f_ffree = mstat.f_ffree; 355 if (sbp != &mp->mnt_stat) { 356 bcopy(&mp->mnt_stat.f_fsid, &sbp->f_fsid, sizeof(sbp->f_fsid)); 357 bcopy(mp->mnt_stat.f_mntonname, sbp->f_mntonname, MNAMELEN); 358 bcopy(mp->mnt_stat.f_mntfromname, sbp->f_mntfromname, MNAMELEN); 359 } 360 return (0); 361} 362 363static int 364nullfs_sync(mp, waitfor, cred, p) 365 struct mount *mp; 366 int waitfor; 367 struct ucred *cred; 368 struct proc *p; 369{ 370 /* 371 * XXX - Assumes no data cached at null layer. 372 */ 373 return (0); 374} 375 376static int 377nullfs_vget(mp, ino, vpp) 378 struct mount *mp; 379 ino_t ino; 380 struct vnode **vpp; 381{ 382 383 return VFS_VGET(MOUNTTONULLMOUNT(mp)->nullm_vfs, ino, vpp); 384} 385 386static int 387nullfs_fhtovp(mp, fidp, nam, vpp, exflagsp, credanonp) 388 struct mount *mp; 389 struct fid *fidp; 390 struct sockaddr *nam; 391 struct vnode **vpp; 392 int *exflagsp; 393 struct ucred**credanonp; 394{ 395 396 return VFS_FHTOVP(MOUNTTONULLMOUNT(mp)->nullm_vfs, fidp, nam, 397 vpp, exflagsp, credanonp); 398} 399 400static int 401nullfs_vptofh(vp, fhp) 402 struct vnode *vp; 403 struct fid *fhp; 404{ 405 return VFS_VPTOFH(NULLVPTOLOWERVP(vp), fhp); 406} 407 408static struct vfsops null_vfsops = { 409 nullfs_mount, 410 nullfs_start, 411 nullfs_unmount, 412 nullfs_root, 413 nullfs_quotactl, 414 nullfs_statfs, 415 nullfs_sync, 416 nullfs_vget, 417 nullfs_fhtovp, 418 nullfs_vptofh, 419 nullfs_init, 420}; 421 422VFS_SET(null_vfsops, null, MOUNT_NULL, VFCF_LOOPBACK); 423