null_vfsops.c revision 50890
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 50890 1999-09-04 12:35:09Z bde $ 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 DEBUG 98 printf("nullfs_mount(mp = %p)\n", (void *)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 DEBUG 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 (void)nullfs_statfs(mp, &mp->mnt_stat, p); 202#ifdef DEBUG 203 printf("nullfs_mount: lower %s, alias at %s\n", 204 mp->mnt_stat.f_mntfromname, mp->mnt_stat.f_mntonname); 205#endif 206 return (0); 207} 208 209/* 210 * VFS start. Nothing needed here - the start routine 211 * on the underlying filesystem will have been called 212 * when that filesystem was mounted. 213 */ 214static int 215nullfs_start(mp, flags, p) 216 struct mount *mp; 217 int flags; 218 struct proc *p; 219{ 220 return (0); 221 /* return VFS_START(MOUNTTONULLMOUNT(mp)->nullm_vfs, flags, p); */ 222} 223 224/* 225 * Free reference to null layer 226 */ 227static int 228nullfs_unmount(mp, mntflags, p) 229 struct mount *mp; 230 int mntflags; 231 struct proc *p; 232{ 233 struct vnode *nullm_rootvp = MOUNTTONULLMOUNT(mp)->nullm_rootvp; 234 int error; 235 int flags = 0; 236 237#ifdef DEBUG 238 printf("nullfs_unmount(mp = %p)\n", (void *)mp); 239#endif 240 241 if (mntflags & MNT_FORCE) 242 flags |= FORCECLOSE; 243 244 /* 245 * Clear out buffer cache. I don't think we 246 * ever get anything cached at this level at the 247 * moment, but who knows... 248 */ 249#if 0 250 mntflushbuf(mp, 0); 251 if (mntinvalbuf(mp, 1)) 252 return (EBUSY); 253#endif 254 if (nullm_rootvp->v_usecount > 1) 255 return (EBUSY); 256 error = vflush(mp, nullm_rootvp, flags); 257 if (error) 258 return (error); 259 260#ifdef DEBUG 261 vprint("alias root of lower", nullm_rootvp); 262#endif 263 /* 264 * Release reference on underlying root vnode 265 */ 266 vrele(nullm_rootvp); 267 /* 268 * And blow it away for future re-use 269 */ 270 vgone(nullm_rootvp); 271 /* 272 * Finally, throw away the null_mount structure 273 */ 274 free(mp->mnt_data, M_NULLFSMNT); /* XXX */ 275 mp->mnt_data = 0; 276 return 0; 277} 278 279static int 280nullfs_root(mp, vpp) 281 struct mount *mp; 282 struct vnode **vpp; 283{ 284 struct proc *p = curproc; /* XXX */ 285 struct vnode *vp; 286 287#ifdef DEBUG 288 printf("nullfs_root(mp = %p, vp = %p->%p)\n", (void *)mp, 289 (void *)MOUNTTONULLMOUNT(mp)->nullm_rootvp, 290 (void *)NULLVPTOLOWERVP(MOUNTTONULLMOUNT(mp)->nullm_rootvp)); 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 DEBUG 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 DEBUG 335 printf("nullfs_statfs(mp = %p, vp = %p->%p)\n", (void *)mp, 336 (void *)MOUNTTONULLMOUNT(mp)->nullm_rootvp, 337 (void *)NULLVPTOLOWERVP(MOUNTTONULLMOUNT(mp)->nullm_rootvp)); 338#endif 339 340 bzero(&mstat, sizeof(mstat)); 341 342 error = VFS_STATFS(MOUNTTONULLMOUNT(mp)->nullm_vfs, &mstat, p); 343 if (error) 344 return (error); 345 346 /* now copy across the "interesting" information and fake the rest */ 347 sbp->f_type = mstat.f_type; 348 sbp->f_flags = mstat.f_flags; 349 sbp->f_bsize = mstat.f_bsize; 350 sbp->f_iosize = mstat.f_iosize; 351 sbp->f_blocks = mstat.f_blocks; 352 sbp->f_bfree = mstat.f_bfree; 353 sbp->f_bavail = mstat.f_bavail; 354 sbp->f_files = mstat.f_files; 355 sbp->f_ffree = mstat.f_ffree; 356 if (sbp != &mp->mnt_stat) { 357 bcopy(&mp->mnt_stat.f_fsid, &sbp->f_fsid, sizeof(sbp->f_fsid)); 358 bcopy(mp->mnt_stat.f_mntonname, sbp->f_mntonname, MNAMELEN); 359 bcopy(mp->mnt_stat.f_mntfromname, sbp->f_mntfromname, MNAMELEN); 360 } 361 return (0); 362} 363 364static int 365nullfs_sync(mp, waitfor, cred, p) 366 struct mount *mp; 367 int waitfor; 368 struct ucred *cred; 369 struct proc *p; 370{ 371 /* 372 * XXX - Assumes no data cached at null layer. 373 */ 374 return (0); 375} 376 377static int 378nullfs_vget(mp, ino, vpp) 379 struct mount *mp; 380 ino_t ino; 381 struct vnode **vpp; 382{ 383 384 return VFS_VGET(MOUNTTONULLMOUNT(mp)->nullm_vfs, ino, vpp); 385} 386 387static int 388nullfs_fhtovp(mp, fidp, nam, vpp, exflagsp, credanonp) 389 struct mount *mp; 390 struct fid *fidp; 391 struct sockaddr *nam; 392 struct vnode **vpp; 393 int *exflagsp; 394 struct ucred**credanonp; 395{ 396 397 return VFS_FHTOVP(MOUNTTONULLMOUNT(mp)->nullm_vfs, fidp, nam, 398 vpp, exflagsp, credanonp); 399} 400 401static int 402nullfs_vptofh(vp, fhp) 403 struct vnode *vp; 404 struct fid *fhp; 405{ 406 return VFS_VPTOFH(NULLVPTOLOWERVP(vp), fhp); 407} 408 409static struct vfsops null_vfsops = { 410 nullfs_mount, 411 nullfs_start, 412 nullfs_unmount, 413 nullfs_root, 414 nullfs_quotactl, 415 nullfs_statfs, 416 nullfs_sync, 417 nullfs_vget, 418 nullfs_fhtovp, 419 nullfs_vptofh, 420 nullfs_init, 421}; 422 423VFS_SET(null_vfsops, null, VFCF_LOOPBACK); 424