null_vfsops.c revision 30354
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 1.19 1997/08/16 19:15:16 wollman 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/malloc.h> 52#include <sys/vnode.h> 53#include <sys/mount.h> 54#include <sys/namei.h> 55#include <miscfs/nullfs/null.h> 56 57static MALLOC_DEFINE(M_NULLFSMNT, "NULLFS mount", "NULLFS mount structure"); 58 59static int nullfs_fhtovp __P((struct mount *mp, struct fid *fidp, 60 struct sockaddr *nam, struct vnode **vpp, 61 int *exflagsp, struct ucred **credanonp)); 62static int nullfs_mount __P((struct mount *mp, char *path, caddr_t data, 63 struct nameidata *ndp, struct proc *p)); 64static int nullfs_quotactl __P((struct mount *mp, int cmd, uid_t uid, 65 caddr_t arg, struct proc *p)); 66static int nullfs_root __P((struct mount *mp, struct vnode **vpp)); 67static int nullfs_start __P((struct mount *mp, int flags, struct proc *p)); 68static int nullfs_statfs __P((struct mount *mp, struct statfs *sbp, 69 struct proc *p)); 70static int nullfs_sync __P((struct mount *mp, int waitfor, 71 struct ucred *cred, struct proc *p)); 72static int nullfs_unmount __P((struct mount *mp, int mntflags, 73 struct proc *p)); 74static int nullfs_vget __P((struct mount *mp, ino_t ino, 75 struct vnode **vpp)); 76static int nullfs_vptofh __P((struct vnode *vp, struct fid *fhp)); 77 78/* 79 * Mount null layer 80 */ 81static int 82nullfs_mount(mp, path, data, ndp, p) 83 struct mount *mp; 84 char *path; 85 caddr_t data; 86 struct nameidata *ndp; 87 struct proc *p; 88{ 89 int error = 0; 90 struct null_args args; 91 struct vnode *lowerrootvp, *vp; 92 struct vnode *nullm_rootvp; 93 struct null_mount *xmp; 94 u_int size; 95 int isvnunlocked = 0; 96 97#ifdef NULLFS_DIAGNOSTIC 98 printf("nullfs_mount(mp = %x)\n", mp); 99#endif 100 101 /* 102 * Update is a no-op 103 */ 104 if (mp->mnt_flag & MNT_UPDATE) { 105 return (EOPNOTSUPP); 106 /* return VFS_MOUNT(MOUNTTONULLMOUNT(mp)->nullm_vfs, path, data, ndp, p);*/ 107 } 108 109 /* 110 * Get argument 111 */ 112 error = copyin(data, (caddr_t)&args, sizeof(struct null_args)); 113 if (error) 114 return (error); 115 116 /* 117 * Unlock lower node to avoid deadlock. 118 * (XXX) VOP_ISLOCKED is needed? 119 */ 120 if ((mp->mnt_vnodecovered->v_op == null_vnodeop_p) && 121 VOP_ISLOCKED(mp->mnt_vnodecovered)) { 122 VOP_UNLOCK(mp->mnt_vnodecovered, 0, p); 123 isvnunlocked = 1; 124 } 125 /* 126 * Find lower node 127 */ 128 NDINIT(ndp, LOOKUP, FOLLOW|WANTPARENT|LOCKLEAF, 129 UIO_USERSPACE, args.target, p); 130 error = namei(ndp); 131 /* 132 * Re-lock vnode. 133 */ 134 if (isvnunlocked && !VOP_ISLOCKED(mp->mnt_vnodecovered)) 135 vn_lock(mp->mnt_vnodecovered, LK_EXCLUSIVE | LK_RETRY, p); 136 137 if (error) 138 return (error); 139 140 /* 141 * Sanity check on lower vnode 142 */ 143 lowerrootvp = ndp->ni_vp; 144 145 vrele(ndp->ni_dvp); 146 ndp->ni_dvp = NULLVP; 147 148 /* 149 * Check multi null mount to avoid `lock against myself' panic. 150 */ 151 if (lowerrootvp == VTONULL(mp->mnt_vnodecovered)->null_lowervp) { 152#ifdef DIAGNOSTIC 153 printf("nullfs_mount: multi null mount?\n"); 154#endif 155 return (EDEADLK); 156 } 157 158 xmp = (struct null_mount *) malloc(sizeof(struct null_mount), 159 M_NULLFSMNT, M_WAITOK); /* XXX */ 160 161 /* 162 * Save reference to underlying FS 163 */ 164 xmp->nullm_vfs = lowerrootvp->v_mount; 165 166 /* 167 * Save reference. Each mount also holds 168 * a reference on the root vnode. 169 */ 170 error = null_node_create(mp, lowerrootvp, &vp); 171 /* 172 * Unlock the node (either the lower or the alias) 173 */ 174 VOP_UNLOCK(vp, 0, p); 175 /* 176 * Make sure the node alias worked 177 */ 178 if (error) { 179 vrele(lowerrootvp); 180 free(xmp, M_NULLFSMNT); /* XXX */ 181 return (error); 182 } 183 184 /* 185 * Keep a held reference to the root vnode. 186 * It is vrele'd in nullfs_unmount. 187 */ 188 nullm_rootvp = vp; 189 nullm_rootvp->v_flag |= VROOT; 190 xmp->nullm_rootvp = nullm_rootvp; 191 if (NULLVPTOLOWERVP(nullm_rootvp)->v_mount->mnt_flag & MNT_LOCAL) 192 mp->mnt_flag |= MNT_LOCAL; 193 mp->mnt_data = (qaddr_t) xmp; 194 vfs_getnewfsid(mp); 195 196 (void) copyinstr(path, mp->mnt_stat.f_mntonname, MNAMELEN - 1, &size); 197 bzero(mp->mnt_stat.f_mntonname + size, MNAMELEN - size); 198 (void) copyinstr(args.target, mp->mnt_stat.f_mntfromname, MNAMELEN - 1, 199 &size); 200 bzero(mp->mnt_stat.f_mntfromname + size, MNAMELEN - size); 201#ifdef NULLFS_DIAGNOSTIC 202 printf("nullfs_mount: lower %s, alias at %s\n", 203 mp->mnt_stat.f_mntfromname, mp->mnt_stat.f_mntonname); 204#endif 205 return (0); 206} 207 208/* 209 * VFS start. Nothing needed here - the start routine 210 * on the underlying filesystem will have been called 211 * when that filesystem was mounted. 212 */ 213static int 214nullfs_start(mp, flags, p) 215 struct mount *mp; 216 int flags; 217 struct proc *p; 218{ 219 return (0); 220 /* return VFS_START(MOUNTTONULLMOUNT(mp)->nullm_vfs, flags, p); */ 221} 222 223/* 224 * Free reference to null layer 225 */ 226static int 227nullfs_unmount(mp, mntflags, p) 228 struct mount *mp; 229 int mntflags; 230 struct proc *p; 231{ 232 struct vnode *nullm_rootvp = MOUNTTONULLMOUNT(mp)->nullm_rootvp; 233 int error; 234 int flags = 0; 235 236#ifdef NULLFS_DIAGNOSTIC 237 printf("nullfs_unmount(mp = %x)\n", mp); 238#endif 239 240 if (mntflags & MNT_FORCE) 241 flags |= FORCECLOSE; 242 243 /* 244 * Clear out buffer cache. I don't think we 245 * ever get anything cached at this level at the 246 * moment, but who knows... 247 */ 248#if 0 249 mntflushbuf(mp, 0); 250 if (mntinvalbuf(mp, 1)) 251 return (EBUSY); 252#endif 253 if (nullm_rootvp->v_usecount > 1) 254 return (EBUSY); 255 error = vflush(mp, nullm_rootvp, flags); 256 if (error) 257 return (error); 258 259#ifdef NULLFS_DIAGNOSTIC 260 vprint("alias root of lower", nullm_rootvp); 261#endif 262 /* 263 * Release reference on underlying root vnode 264 */ 265 vrele(nullm_rootvp); 266 /* 267 * And blow it away for future re-use 268 */ 269 vgone(nullm_rootvp); 270 /* 271 * Finally, throw away the null_mount structure 272 */ 273 free(mp->mnt_data, M_NULLFSMNT); /* XXX */ 274 mp->mnt_data = 0; 275 return 0; 276} 277 278static int 279nullfs_root(mp, vpp) 280 struct mount *mp; 281 struct vnode **vpp; 282{ 283 struct proc *p = curproc; /* XXX */ 284 struct vnode *vp; 285 286#ifdef NULLFS_DIAGNOSTIC 287 printf("nullfs_root(mp = %x, vp = %x->%x)\n", mp, 288 MOUNTTONULLMOUNT(mp)->nullm_rootvp, 289 NULLVPTOLOWERVP(MOUNTTONULLMOUNT(mp)->nullm_rootvp) 290 ); 291#endif 292 293 /* 294 * Return locked reference to root. 295 */ 296 vp = MOUNTTONULLMOUNT(mp)->nullm_rootvp; 297 VREF(vp); 298 if (VOP_ISLOCKED(vp)) { 299 /* 300 * XXX 301 * Should we check type of node? 302 */ 303#ifdef DIAGNOSTIC 304 printf("nullfs_root: multi null mount?\n"); 305#endif 306 vrele(vp); 307 return (EDEADLK); 308 } else 309 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, p); 310 *vpp = vp; 311 return 0; 312} 313 314static int 315nullfs_quotactl(mp, cmd, uid, arg, p) 316 struct mount *mp; 317 int cmd; 318 uid_t uid; 319 caddr_t arg; 320 struct proc *p; 321{ 322 return VFS_QUOTACTL(MOUNTTONULLMOUNT(mp)->nullm_vfs, cmd, uid, arg, p); 323} 324 325static int 326nullfs_statfs(mp, sbp, p) 327 struct mount *mp; 328 struct statfs *sbp; 329 struct proc *p; 330{ 331 int error; 332 struct statfs mstat; 333 334#ifdef NULLFS_DIAGNOSTIC 335 printf("nullfs_statfs(mp = %x, vp = %x->%x)\n", mp, 336 MOUNTTONULLMOUNT(mp)->nullm_rootvp, 337 NULLVPTOLOWERVP(MOUNTTONULLMOUNT(mp)->nullm_rootvp) 338 ); 339#endif 340 341 bzero(&mstat, sizeof(mstat)); 342 343 error = VFS_STATFS(MOUNTTONULLMOUNT(mp)->nullm_vfs, &mstat, p); 344 if (error) 345 return (error); 346 347 /* now copy across the "interesting" information and fake the rest */ 348 sbp->f_type = mstat.f_type; 349 sbp->f_flags = mstat.f_flags; 350 sbp->f_bsize = mstat.f_bsize; 351 sbp->f_iosize = mstat.f_iosize; 352 sbp->f_blocks = mstat.f_blocks; 353 sbp->f_bfree = mstat.f_bfree; 354 sbp->f_bavail = mstat.f_bavail; 355 sbp->f_files = mstat.f_files; 356 sbp->f_ffree = mstat.f_ffree; 357 if (sbp != &mp->mnt_stat) { 358 bcopy(&mp->mnt_stat.f_fsid, &sbp->f_fsid, sizeof(sbp->f_fsid)); 359 bcopy(mp->mnt_stat.f_mntonname, sbp->f_mntonname, MNAMELEN); 360 bcopy(mp->mnt_stat.f_mntfromname, sbp->f_mntfromname, MNAMELEN); 361 } 362 return (0); 363} 364 365static int 366nullfs_sync(mp, waitfor, cred, p) 367 struct mount *mp; 368 int waitfor; 369 struct ucred *cred; 370 struct proc *p; 371{ 372 /* 373 * XXX - Assumes no data cached at null layer. 374 */ 375 return (0); 376} 377 378static int 379nullfs_vget(mp, ino, vpp) 380 struct mount *mp; 381 ino_t ino; 382 struct vnode **vpp; 383{ 384 385 return VFS_VGET(MOUNTTONULLMOUNT(mp)->nullm_vfs, ino, vpp); 386} 387 388static int 389nullfs_fhtovp(mp, fidp, nam, vpp, exflagsp, credanonp) 390 struct mount *mp; 391 struct fid *fidp; 392 struct sockaddr *nam; 393 struct vnode **vpp; 394 int *exflagsp; 395 struct ucred**credanonp; 396{ 397 398 return VFS_FHTOVP(MOUNTTONULLMOUNT(mp)->nullm_vfs, fidp, nam, 399 vpp, exflagsp, credanonp); 400} 401 402static int 403nullfs_vptofh(vp, fhp) 404 struct vnode *vp; 405 struct fid *fhp; 406{ 407 return VFS_VPTOFH(NULLVPTOLOWERVP(vp), fhp); 408} 409 410static struct vfsops null_vfsops = { 411 nullfs_mount, 412 nullfs_start, 413 nullfs_unmount, 414 nullfs_root, 415 nullfs_quotactl, 416 nullfs_statfs, 417 nullfs_sync, 418 nullfs_vget, 419 nullfs_fhtovp, 420 nullfs_vptofh, 421 nullfs_init, 422}; 423 424VFS_SET(null_vfsops, null, MOUNT_NULL, VFCF_LOOPBACK); 425