null_vfsops.c revision 73286
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 * $FreeBSD: head/sys/fs/nullfs/null_vfsops.c 73286 2001-03-01 21:00:17Z adrian $ 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/malloc.h> 51#include <sys/vnode.h> 52#include <sys/mount.h> 53#include <sys/namei.h> 54#include <miscfs/nullfs/null.h> 55 56static MALLOC_DEFINE(M_NULLFSMNT, "NULLFS mount", "NULLFS mount structure"); 57 58static int nullfs_fhtovp(struct mount *mp, struct fid *fidp, 59 struct vnode **vpp); 60static int nullfs_checkexp(struct mount *mp, struct sockaddr *nam, 61 int *extflagsp, struct ucred **credanonp); 62static int nullfs_mount(struct mount *mp, char *path, caddr_t data, 63 struct nameidata *ndp, struct proc *p); 64static int nullfs_quotactl(struct mount *mp, int cmd, uid_t uid, 65 caddr_t arg, struct proc *p); 66static int nullfs_root(struct mount *mp, struct vnode **vpp); 67static int nullfs_start(struct mount *mp, int flags, struct proc *p); 68static int nullfs_statfs(struct mount *mp, struct statfs *sbp, 69 struct proc *p); 70static int nullfs_sync(struct mount *mp, int waitfor, 71 struct ucred *cred, struct proc *p); 72static int nullfs_unmount(struct mount *mp, int mntflags, struct proc *p); 73static int nullfs_vget(struct mount *mp, ino_t ino, struct vnode **vpp); 74static int nullfs_vptofh(struct vnode *vp, struct fid *fhp); 75static int nullfs_extattrctl(struct mount *mp, int cmd, 76 const char *attrname, caddr_t arg, struct proc *p); 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 NULLFSDEBUG("nullfs_mount(mp = %p)\n", (void *)mp); 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, NULL)) { 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, NULL)) 133 vn_lock(mp->mnt_vnodecovered, LK_EXCLUSIVE | LK_RETRY, p); 134 135 if (error) 136 return (error); 137 NDFREE(ndp, NDF_ONLY_PNBUF); 138 139 /* 140 * Sanity check on lower vnode 141 */ 142 lowerrootvp = ndp->ni_vp; 143 144 vrele(ndp->ni_dvp); 145 ndp->ni_dvp = NULLVP; 146 147 /* 148 * Check multi null mount to avoid `lock against myself' panic. 149 */ 150 if (lowerrootvp == VTONULL(mp->mnt_vnodecovered)->null_lowervp) { 151 NULLFSDEBUG("nullfs_mount: multi null mount?\n"); 152 vput(lowerrootvp); 153 return (EDEADLK); 154 } 155 156 xmp = (struct null_mount *) malloc(sizeof(struct null_mount), 157 M_NULLFSMNT, 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_NULLFSMNT); /* 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(args.target, mp->mnt_stat.f_mntfromname, MNAMELEN - 1, 195 &size); 196 bzero(mp->mnt_stat.f_mntfromname + size, MNAMELEN - size); 197 (void)nullfs_statfs(mp, &mp->mnt_stat, p); 198 NULLFSDEBUG("nullfs_mount: lower %s, alias at %s\n", 199 mp->mnt_stat.f_mntfromname, mp->mnt_stat.f_mntonname); 200 return (0); 201} 202 203/* 204 * VFS start. Nothing needed here - the start routine 205 * on the underlying filesystem will have been called 206 * when that filesystem was mounted. 207 */ 208static int 209nullfs_start(mp, flags, p) 210 struct mount *mp; 211 int flags; 212 struct proc *p; 213{ 214 return (0); 215 /* return VFS_START(MOUNTTONULLMOUNT(mp)->nullm_vfs, flags, p); */ 216} 217 218/* 219 * Free reference to null layer 220 */ 221static int 222nullfs_unmount(mp, mntflags, p) 223 struct mount *mp; 224 int mntflags; 225 struct proc *p; 226{ 227 struct vnode *vp = MOUNTTONULLMOUNT(mp)->nullm_rootvp; 228 void *mntdata; 229 int error; 230 int flags = 0; 231 232 NULLFSDEBUG("nullfs_unmount: mp = %p\n", (void *)mp); 233 234 if (mntflags & MNT_FORCE) 235 flags |= FORCECLOSE; 236 237 error = VFS_ROOT(mp, &vp); 238 if (error) 239 return (error); 240 if (vp->v_usecount > 2) { 241 NULLFSDEBUG("nullfs_unmount: rootvp is busy(%d)\n", 242 vp->v_usecount); 243 vput(vp); 244 return (EBUSY); 245 } 246 error = vflush(mp, vp, flags); 247 if (error) 248 return (error); 249 250#ifdef NULLFS_DEBUG 251 vprint("alias root of lower", vp); 252#endif 253 vput(vp); 254 /* 255 * Release reference on underlying root vnode 256 */ 257 vrele(vp); 258 /* 259 * And blow it away for future re-use 260 */ 261 vgone(vp); 262 /* 263 * Finally, throw away the null_mount structure 264 */ 265 mntdata = mp->mnt_data; 266 mp->mnt_data = 0; 267 free(mntdata, M_NULLFSMNT); 268 return 0; 269} 270 271static int 272nullfs_root(mp, vpp) 273 struct mount *mp; 274 struct vnode **vpp; 275{ 276 struct proc *p = curproc; /* XXX */ 277 struct vnode *vp; 278 279 NULLFSDEBUG("nullfs_root(mp = %p, vp = %p->%p)\n", (void *)mp, 280 (void *)MOUNTTONULLMOUNT(mp)->nullm_rootvp, 281 (void *)NULLVPTOLOWERVP(MOUNTTONULLMOUNT(mp)->nullm_rootvp)); 282 283 /* 284 * Return locked reference to root. 285 */ 286 vp = MOUNTTONULLMOUNT(mp)->nullm_rootvp; 287 VREF(vp); 288 289#ifdef NULLFS_DEBUG 290 if (VOP_ISLOCKED(vp, NULL)) { 291 Debugger("root vnode is locked.\n"); 292 vrele(vp); 293 return (EDEADLK); 294 } 295#endif 296 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, p); 297 *vpp = vp; 298 return 0; 299} 300 301static int 302nullfs_quotactl(mp, cmd, uid, arg, p) 303 struct mount *mp; 304 int cmd; 305 uid_t uid; 306 caddr_t arg; 307 struct proc *p; 308{ 309 return VFS_QUOTACTL(MOUNTTONULLMOUNT(mp)->nullm_vfs, cmd, uid, arg, p); 310} 311 312static int 313nullfs_statfs(mp, sbp, p) 314 struct mount *mp; 315 struct statfs *sbp; 316 struct proc *p; 317{ 318 int error; 319 struct statfs mstat; 320 321 NULLFSDEBUG("nullfs_statfs(mp = %p, vp = %p->%p)\n", (void *)mp, 322 (void *)MOUNTTONULLMOUNT(mp)->nullm_rootvp, 323 (void *)NULLVPTOLOWERVP(MOUNTTONULLMOUNT(mp)->nullm_rootvp)); 324 325 bzero(&mstat, sizeof(mstat)); 326 327 error = VFS_STATFS(MOUNTTONULLMOUNT(mp)->nullm_vfs, &mstat, p); 328 if (error) 329 return (error); 330 331 /* now copy across the "interesting" information and fake the rest */ 332 sbp->f_type = mstat.f_type; 333 sbp->f_flags = mstat.f_flags; 334 sbp->f_bsize = mstat.f_bsize; 335 sbp->f_iosize = mstat.f_iosize; 336 sbp->f_blocks = mstat.f_blocks; 337 sbp->f_bfree = mstat.f_bfree; 338 sbp->f_bavail = mstat.f_bavail; 339 sbp->f_files = mstat.f_files; 340 sbp->f_ffree = mstat.f_ffree; 341 if (sbp != &mp->mnt_stat) { 342 bcopy(&mp->mnt_stat.f_fsid, &sbp->f_fsid, sizeof(sbp->f_fsid)); 343 bcopy(mp->mnt_stat.f_mntonname, sbp->f_mntonname, MNAMELEN); 344 bcopy(mp->mnt_stat.f_mntfromname, sbp->f_mntfromname, MNAMELEN); 345 } 346 return (0); 347} 348 349static int 350nullfs_sync(mp, waitfor, cred, p) 351 struct mount *mp; 352 int waitfor; 353 struct ucred *cred; 354 struct proc *p; 355{ 356 /* 357 * XXX - Assumes no data cached at null layer. 358 */ 359 return (0); 360} 361 362static int 363nullfs_vget(mp, ino, vpp) 364 struct mount *mp; 365 ino_t ino; 366 struct vnode **vpp; 367{ 368 int error; 369 error = VFS_VGET(MOUNTTONULLMOUNT(mp)->nullm_vfs, ino, vpp); 370 if (error) 371 return (error); 372 373 return (null_node_create(mp, *vpp, vpp)); 374} 375 376static int 377nullfs_fhtovp(mp, fidp, vpp) 378 struct mount *mp; 379 struct fid *fidp; 380 struct vnode **vpp; 381{ 382 int error; 383 error = VFS_FHTOVP(MOUNTTONULLMOUNT(mp)->nullm_vfs, fidp, vpp); 384 if (error) 385 return (error); 386 387 return (null_node_create(mp, *vpp, vpp)); 388} 389 390static int 391nullfs_checkexp(mp, nam, extflagsp, credanonp) 392 struct mount *mp; 393 struct sockaddr *nam; 394 int *extflagsp; 395 struct ucred **credanonp; 396{ 397 398 return VFS_CHECKEXP(MOUNTTONULLMOUNT(mp)->nullm_vfs, nam, 399 extflagsp, 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 int 411nullfs_extattrctl(mp, cmd, attrname, arg, p) 412 struct mount *mp; 413 int cmd; 414 const char *attrname; 415 caddr_t arg; 416 struct proc *p; 417{ 418 return VFS_EXTATTRCTL(MOUNTTONULLMOUNT(mp)->nullm_vfs, cmd, attrname, 419 arg, p); 420} 421 422 423static struct vfsops null_vfsops = { 424 nullfs_mount, 425 nullfs_start, 426 nullfs_unmount, 427 nullfs_root, 428 nullfs_quotactl, 429 nullfs_statfs, 430 nullfs_sync, 431 nullfs_vget, 432 nullfs_fhtovp, 433 nullfs_checkexp, 434 nullfs_vptofh, 435 nullfs_init, 436 nullfs_uninit, 437 nullfs_extattrctl, 438}; 439 440VFS_SET(null_vfsops, nullfs, VFCF_LOOPBACK); 441