null_vfsops.c revision 153400
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 153400 2005-12-14 00:49:52Z des $ 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/kdb.h> 46#include <sys/kernel.h> 47#include <sys/lock.h> 48#include <sys/malloc.h> 49#include <sys/mount.h> 50#include <sys/namei.h> 51#include <sys/proc.h> 52#include <sys/vnode.h> 53 54#include <fs/nullfs/null.h> 55 56static MALLOC_DEFINE(M_NULLFSMNT, "nullfs_mount", "NULLFS mount structure"); 57 58static vfs_fhtovp_t nullfs_fhtovp; 59static vfs_checkexp_t nullfs_checkexp; 60static vfs_mount_t nullfs_mount; 61static vfs_quotactl_t nullfs_quotactl; 62static vfs_root_t nullfs_root; 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(struct mount *mp, struct thread *td) 75{ 76 int error = 0; 77 struct vnode *lowerrootvp, *vp; 78 struct vnode *nullm_rootvp; 79 struct null_mount *xmp; 80 char *target; 81 int isvnunlocked = 0, len; 82 struct nameidata nd, *ndp = &nd; 83 84 NULLFSDEBUG("nullfs_mount(mp = %p)\n", (void *)mp); 85 86 if (mp->mnt_flag & MNT_ROOTFS) 87 return (EOPNOTSUPP); 88 /* 89 * Update is a no-op 90 */ 91 if (mp->mnt_flag & MNT_UPDATE) { 92 return (EOPNOTSUPP); 93 /* return VFS_MOUNT(MOUNTTONULLMOUNT(mp)->nullm_vfs, path, data, ndp, td);*/ 94 } 95 96 /* 97 * Get argument 98 */ 99 error = vfs_getopt(mp->mnt_optnew, "target", (void **)&target, &len); 100 if (error || target[len - 1] != '\0') 101 return (EINVAL); 102 103 /* 104 * Unlock lower node to avoid deadlock. 105 * (XXX) VOP_ISLOCKED is needed? 106 */ 107 if ((mp->mnt_vnodecovered->v_op == &null_vnodeops) && 108 VOP_ISLOCKED(mp->mnt_vnodecovered, NULL)) { 109 VOP_UNLOCK(mp->mnt_vnodecovered, 0, td); 110 isvnunlocked = 1; 111 } 112 /* 113 * Find lower node 114 */ 115 NDINIT(ndp, LOOKUP, FOLLOW|WANTPARENT|LOCKLEAF, 116 UIO_SYSSPACE, target, td); 117 error = namei(ndp); 118 /* 119 * Re-lock vnode. 120 */ 121 if (isvnunlocked && !VOP_ISLOCKED(mp->mnt_vnodecovered, NULL)) 122 vn_lock(mp->mnt_vnodecovered, LK_EXCLUSIVE | LK_RETRY, td); 123 124 if (error) 125 return (error); 126 NDFREE(ndp, NDF_ONLY_PNBUF); 127 128 /* 129 * Sanity check on lower vnode 130 */ 131 lowerrootvp = ndp->ni_vp; 132 133 vrele(ndp->ni_dvp); 134 ndp->ni_dvp = NULLVP; 135 136 /* 137 * Check multi null mount to avoid `lock against myself' panic. 138 */ 139 if (lowerrootvp == VTONULL(mp->mnt_vnodecovered)->null_lowervp) { 140 NULLFSDEBUG("nullfs_mount: multi null mount?\n"); 141 vput(lowerrootvp); 142 return (EDEADLK); 143 } 144 145 xmp = (struct null_mount *) malloc(sizeof(struct null_mount), 146 M_NULLFSMNT, M_WAITOK); /* XXX */ 147 148 /* 149 * Save reference to underlying FS 150 */ 151 xmp->nullm_vfs = lowerrootvp->v_mount; 152 153 /* 154 * Save reference. Each mount also holds 155 * a reference on the root vnode. 156 */ 157 error = null_nodeget(mp, lowerrootvp, &vp); 158 /* 159 * Make sure the node alias worked 160 */ 161 if (error) { 162 VOP_UNLOCK(vp, 0, td); 163 vrele(lowerrootvp); 164 free(xmp, M_NULLFSMNT); /* XXX */ 165 return (error); 166 } 167 168 /* 169 * Keep a held reference to the root vnode. 170 * It is vrele'd in nullfs_unmount. 171 */ 172 nullm_rootvp = vp; 173 nullm_rootvp->v_vflag |= VV_ROOT; 174 xmp->nullm_rootvp = nullm_rootvp; 175 176 /* 177 * Unlock the node (either the lower or the alias) 178 */ 179 VOP_UNLOCK(vp, 0, td); 180 181 if (NULLVPTOLOWERVP(nullm_rootvp)->v_mount->mnt_flag & MNT_LOCAL) 182 mp->mnt_flag |= MNT_LOCAL; 183 mp->mnt_kern_flag |= lowerrootvp->v_mount->mnt_kern_flag | MNTK_MPSAFE; 184 mp->mnt_data = (qaddr_t) xmp; 185 vfs_getnewfsid(mp); 186 187 vfs_mountedfrom(mp, target); 188 189 NULLFSDEBUG("nullfs_mount: lower %s, alias at %s\n", 190 mp->mnt_stat.f_mntfromname, mp->mnt_stat.f_mntonname); 191 return (0); 192} 193 194/* 195 * Free reference to null layer 196 */ 197static int 198nullfs_unmount(mp, mntflags, td) 199 struct mount *mp; 200 int mntflags; 201 struct thread *td; 202{ 203 void *mntdata; 204 int error; 205 int flags = 0; 206 207 NULLFSDEBUG("nullfs_unmount: mp = %p\n", (void *)mp); 208 209 if (mntflags & MNT_FORCE) 210 flags |= FORCECLOSE; 211 212 /* There is 1 extra root vnode reference (nullm_rootvp). */ 213 error = vflush(mp, 1, flags, td); 214 if (error) 215 return (error); 216 217 /* 218 * Finally, throw away the null_mount structure 219 */ 220 mntdata = mp->mnt_data; 221 mp->mnt_data = 0; 222 free(mntdata, M_NULLFSMNT); 223 return 0; 224} 225 226static int 227nullfs_root(mp, flags, vpp, td) 228 struct mount *mp; 229 int flags; 230 struct vnode **vpp; 231 struct thread *td; 232{ 233 struct vnode *vp; 234 235 NULLFSDEBUG("nullfs_root(mp = %p, vp = %p->%p)\n", (void *)mp, 236 (void *)MOUNTTONULLMOUNT(mp)->nullm_rootvp, 237 (void *)NULLVPTOLOWERVP(MOUNTTONULLMOUNT(mp)->nullm_rootvp)); 238 239 /* 240 * Return locked reference to root. 241 */ 242 vp = MOUNTTONULLMOUNT(mp)->nullm_rootvp; 243 VREF(vp); 244 245#ifdef NULLFS_DEBUG 246 if (VOP_ISLOCKED(vp, NULL)) { 247 kdb_enter("root vnode is locked.\n"); 248 vrele(vp); 249 return (EDEADLK); 250 } 251#endif 252 vn_lock(vp, flags | LK_RETRY, td); 253 *vpp = vp; 254 return 0; 255} 256 257static int 258nullfs_quotactl(mp, cmd, uid, arg, td) 259 struct mount *mp; 260 int cmd; 261 uid_t uid; 262 void *arg; 263 struct thread *td; 264{ 265 return VFS_QUOTACTL(MOUNTTONULLMOUNT(mp)->nullm_vfs, cmd, uid, arg, td); 266} 267 268static int 269nullfs_statfs(mp, sbp, td) 270 struct mount *mp; 271 struct statfs *sbp; 272 struct thread *td; 273{ 274 int error; 275 struct statfs mstat; 276 277 NULLFSDEBUG("nullfs_statfs(mp = %p, vp = %p->%p)\n", (void *)mp, 278 (void *)MOUNTTONULLMOUNT(mp)->nullm_rootvp, 279 (void *)NULLVPTOLOWERVP(MOUNTTONULLMOUNT(mp)->nullm_rootvp)); 280 281 bzero(&mstat, sizeof(mstat)); 282 283 error = VFS_STATFS(MOUNTTONULLMOUNT(mp)->nullm_vfs, &mstat, td); 284 if (error) 285 return (error); 286 287 /* now copy across the "interesting" information and fake the rest */ 288 sbp->f_type = mstat.f_type; 289 sbp->f_flags = mstat.f_flags; 290 sbp->f_bsize = mstat.f_bsize; 291 sbp->f_iosize = mstat.f_iosize; 292 sbp->f_blocks = mstat.f_blocks; 293 sbp->f_bfree = mstat.f_bfree; 294 sbp->f_bavail = mstat.f_bavail; 295 sbp->f_files = mstat.f_files; 296 sbp->f_ffree = mstat.f_ffree; 297 return (0); 298} 299 300static int 301nullfs_sync(mp, waitfor, td) 302 struct mount *mp; 303 int waitfor; 304 struct thread *td; 305{ 306 /* 307 * XXX - Assumes no data cached at null layer. 308 */ 309 return (0); 310} 311 312static int 313nullfs_vget(mp, ino, flags, vpp) 314 struct mount *mp; 315 ino_t ino; 316 int flags; 317 struct vnode **vpp; 318{ 319 int error; 320 error = VFS_VGET(MOUNTTONULLMOUNT(mp)->nullm_vfs, ino, flags, vpp); 321 if (error) 322 return (error); 323 324 return (null_nodeget(mp, *vpp, vpp)); 325} 326 327static int 328nullfs_fhtovp(mp, fidp, vpp) 329 struct mount *mp; 330 struct fid *fidp; 331 struct vnode **vpp; 332{ 333 int error; 334 error = VFS_FHTOVP(MOUNTTONULLMOUNT(mp)->nullm_vfs, fidp, vpp); 335 if (error) 336 return (error); 337 338 return (null_nodeget(mp, *vpp, vpp)); 339} 340 341static int 342nullfs_checkexp(mp, nam, extflagsp, credanonp) 343 struct mount *mp; 344 struct sockaddr *nam; 345 int *extflagsp; 346 struct ucred **credanonp; 347{ 348 349 return VFS_CHECKEXP(MOUNTTONULLMOUNT(mp)->nullm_vfs, nam, 350 extflagsp, credanonp); 351} 352 353static int 354nullfs_vptofh(vp, fhp) 355 struct vnode *vp; 356 struct fid *fhp; 357{ 358 struct vnode *lvp; 359 360 lvp = NULLVPTOLOWERVP(vp); 361 return VFS_VPTOFH(lvp, fhp); 362} 363 364static int 365nullfs_extattrctl(mp, cmd, filename_vp, namespace, attrname, td) 366 struct mount *mp; 367 int cmd; 368 struct vnode *filename_vp; 369 int namespace; 370 const char *attrname; 371 struct thread *td; 372{ 373 return VFS_EXTATTRCTL(MOUNTTONULLMOUNT(mp)->nullm_vfs, cmd, filename_vp, 374 namespace, attrname, td); 375} 376 377 378static struct vfsops null_vfsops = { 379 .vfs_checkexp = nullfs_checkexp, 380 .vfs_extattrctl = nullfs_extattrctl, 381 .vfs_fhtovp = nullfs_fhtovp, 382 .vfs_init = nullfs_init, 383 .vfs_mount = nullfs_mount, 384 .vfs_quotactl = nullfs_quotactl, 385 .vfs_root = nullfs_root, 386 .vfs_statfs = nullfs_statfs, 387 .vfs_sync = nullfs_sync, 388 .vfs_uninit = nullfs_uninit, 389 .vfs_unmount = nullfs_unmount, 390 .vfs_vget = nullfs_vget, 391 .vfs_vptofh = nullfs_vptofh, 392}; 393 394VFS_SET(null_vfsops, nullfs, VFCF_LOOPBACK); 395