null_vfsops.c revision 159023
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 159023 2006-05-28 22:45:52Z rodrigc $ 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_mount_t nullfs_mount; 60static vfs_quotactl_t nullfs_quotactl; 61static vfs_root_t nullfs_root; 62static vfs_sync_t nullfs_sync; 63static vfs_statfs_t nullfs_statfs; 64static vfs_unmount_t nullfs_unmount; 65static vfs_vget_t nullfs_vget; 66static vfs_vptofh_t nullfs_vptofh; 67static vfs_extattrctl_t nullfs_extattrctl; 68 69/* 70 * Mount null layer 71 */ 72static int 73nullfs_mount(struct mount *mp, struct thread *td) 74{ 75 int error = 0; 76 struct vnode *lowerrootvp, *vp; 77 struct vnode *nullm_rootvp; 78 struct null_mount *xmp; 79 char *target; 80 int isvnunlocked = 0, len; 81 struct nameidata nd, *ndp = &nd; 82 83 NULLFSDEBUG("nullfs_mount(mp = %p)\n", (void *)mp); 84 85 if (mp->mnt_flag & MNT_ROOTFS) 86 return (EOPNOTSUPP); 87 /* 88 * Update is a no-op 89 */ 90 if (mp->mnt_flag & MNT_UPDATE) { 91 /* 92 * Only support update mounts for NFS export. 93 */ 94 if (vfs_flagopt(mp->mnt_optnew, "export", NULL, 0)) 95 return (0); 96 else 97 return (EOPNOTSUPP); 98 } 99 100 /* 101 * Get argument 102 */ 103 error = vfs_getopt(mp->mnt_optnew, "target", (void **)&target, &len); 104 if (error || target[len - 1] != '\0') 105 return (EINVAL); 106 107 /* 108 * Unlock lower node to avoid deadlock. 109 * (XXX) VOP_ISLOCKED is needed? 110 */ 111 if ((mp->mnt_vnodecovered->v_op == &null_vnodeops) && 112 VOP_ISLOCKED(mp->mnt_vnodecovered, NULL)) { 113 VOP_UNLOCK(mp->mnt_vnodecovered, 0, td); 114 isvnunlocked = 1; 115 } 116 /* 117 * Find lower node 118 */ 119 NDINIT(ndp, LOOKUP, FOLLOW|LOCKLEAF, 120 UIO_SYSSPACE, target, td); 121 error = namei(ndp); 122 /* 123 * Re-lock vnode. 124 */ 125 if (isvnunlocked && !VOP_ISLOCKED(mp->mnt_vnodecovered, NULL)) 126 vn_lock(mp->mnt_vnodecovered, LK_EXCLUSIVE | LK_RETRY, td); 127 128 if (error) 129 return (error); 130 NDFREE(ndp, NDF_ONLY_PNBUF); 131 132 /* 133 * Sanity check on lower vnode 134 */ 135 lowerrootvp = ndp->ni_vp; 136 137 /* 138 * Check multi null mount to avoid `lock against myself' panic. 139 */ 140 if (lowerrootvp == VTONULL(mp->mnt_vnodecovered)->null_lowervp) { 141 NULLFSDEBUG("nullfs_mount: multi null mount?\n"); 142 vput(lowerrootvp); 143 return (EDEADLK); 144 } 145 146 xmp = (struct null_mount *) malloc(sizeof(struct null_mount), 147 M_NULLFSMNT, M_WAITOK); /* XXX */ 148 149 /* 150 * Save reference to underlying FS 151 */ 152 xmp->nullm_vfs = lowerrootvp->v_mount; 153 154 /* 155 * Save reference. Each mount also holds 156 * a reference on the root vnode. 157 */ 158 error = null_nodeget(mp, lowerrootvp, &vp); 159 /* 160 * Make sure the node alias worked 161 */ 162 if (error) { 163 VOP_UNLOCK(vp, 0, td); 164 vrele(lowerrootvp); 165 free(xmp, M_NULLFSMNT); /* XXX */ 166 return (error); 167 } 168 169 /* 170 * Keep a held reference to the root vnode. 171 * It is vrele'd in nullfs_unmount. 172 */ 173 nullm_rootvp = vp; 174 nullm_rootvp->v_vflag |= VV_ROOT; 175 xmp->nullm_rootvp = nullm_rootvp; 176 177 /* 178 * Unlock the node (either the lower or the alias) 179 */ 180 VOP_UNLOCK(vp, 0, td); 181 182 if (NULLVPTOLOWERVP(nullm_rootvp)->v_mount->mnt_flag & MNT_LOCAL) 183 mp->mnt_flag |= MNT_LOCAL; 184 mp->mnt_kern_flag |= lowerrootvp->v_mount->mnt_kern_flag & MNTK_MPSAFE; 185 mp->mnt_data = (qaddr_t) xmp; 186 vfs_getnewfsid(mp); 187 188 vfs_mountedfrom(mp, target); 189 190 NULLFSDEBUG("nullfs_mount: lower %s, alias at %s\n", 191 mp->mnt_stat.f_mntfromname, mp->mnt_stat.f_mntonname); 192 return (0); 193} 194 195/* 196 * Free reference to null layer 197 */ 198static int 199nullfs_unmount(mp, mntflags, td) 200 struct mount *mp; 201 int mntflags; 202 struct thread *td; 203{ 204 void *mntdata; 205 int error; 206 int flags = 0; 207 208 NULLFSDEBUG("nullfs_unmount: mp = %p\n", (void *)mp); 209 210 if (mntflags & MNT_FORCE) 211 flags |= FORCECLOSE; 212 213 /* There is 1 extra root vnode reference (nullm_rootvp). */ 214 error = vflush(mp, 1, flags, td); 215 if (error) 216 return (error); 217 218 /* 219 * Finally, throw away the null_mount structure 220 */ 221 mntdata = mp->mnt_data; 222 mp->mnt_data = 0; 223 free(mntdata, M_NULLFSMNT); 224 return 0; 225} 226 227static int 228nullfs_root(mp, flags, vpp, td) 229 struct mount *mp; 230 int flags; 231 struct vnode **vpp; 232 struct thread *td; 233{ 234 struct vnode *vp; 235 236 NULLFSDEBUG("nullfs_root(mp = %p, vp = %p->%p)\n", (void *)mp, 237 (void *)MOUNTTONULLMOUNT(mp)->nullm_rootvp, 238 (void *)NULLVPTOLOWERVP(MOUNTTONULLMOUNT(mp)->nullm_rootvp)); 239 240 /* 241 * Return locked reference to root. 242 */ 243 vp = MOUNTTONULLMOUNT(mp)->nullm_rootvp; 244 VREF(vp); 245 246#ifdef NULLFS_DEBUG 247 if (VOP_ISLOCKED(vp, NULL)) { 248 kdb_enter("root vnode is locked.\n"); 249 vrele(vp); 250 return (EDEADLK); 251 } 252#endif 253 vn_lock(vp, flags | LK_RETRY, td); 254 *vpp = vp; 255 return 0; 256} 257 258static int 259nullfs_quotactl(mp, cmd, uid, arg, td) 260 struct mount *mp; 261 int cmd; 262 uid_t uid; 263 void *arg; 264 struct thread *td; 265{ 266 return VFS_QUOTACTL(MOUNTTONULLMOUNT(mp)->nullm_vfs, cmd, uid, arg, td); 267} 268 269static int 270nullfs_statfs(mp, sbp, td) 271 struct mount *mp; 272 struct statfs *sbp; 273 struct thread *td; 274{ 275 int error; 276 struct statfs mstat; 277 278 NULLFSDEBUG("nullfs_statfs(mp = %p, vp = %p->%p)\n", (void *)mp, 279 (void *)MOUNTTONULLMOUNT(mp)->nullm_rootvp, 280 (void *)NULLVPTOLOWERVP(MOUNTTONULLMOUNT(mp)->nullm_rootvp)); 281 282 bzero(&mstat, sizeof(mstat)); 283 284 error = VFS_STATFS(MOUNTTONULLMOUNT(mp)->nullm_vfs, &mstat, td); 285 if (error) 286 return (error); 287 288 /* now copy across the "interesting" information and fake the rest */ 289 sbp->f_type = mstat.f_type; 290 sbp->f_flags = mstat.f_flags; 291 sbp->f_bsize = mstat.f_bsize; 292 sbp->f_iosize = mstat.f_iosize; 293 sbp->f_blocks = mstat.f_blocks; 294 sbp->f_bfree = mstat.f_bfree; 295 sbp->f_bavail = mstat.f_bavail; 296 sbp->f_files = mstat.f_files; 297 sbp->f_ffree = mstat.f_ffree; 298 return (0); 299} 300 301static int 302nullfs_sync(mp, waitfor, td) 303 struct mount *mp; 304 int waitfor; 305 struct thread *td; 306{ 307 /* 308 * XXX - Assumes no data cached at null layer. 309 */ 310 return (0); 311} 312 313static int 314nullfs_vget(mp, ino, flags, vpp) 315 struct mount *mp; 316 ino_t ino; 317 int flags; 318 struct vnode **vpp; 319{ 320 int error; 321 error = VFS_VGET(MOUNTTONULLMOUNT(mp)->nullm_vfs, ino, flags, vpp); 322 if (error) 323 return (error); 324 325 return (null_nodeget(mp, *vpp, vpp)); 326} 327 328static int 329nullfs_fhtovp(mp, fidp, vpp) 330 struct mount *mp; 331 struct fid *fidp; 332 struct vnode **vpp; 333{ 334 int error; 335 error = VFS_FHTOVP(MOUNTTONULLMOUNT(mp)->nullm_vfs, fidp, vpp); 336 if (error) 337 return (error); 338 339 return (null_nodeget(mp, *vpp, vpp)); 340} 341 342static int 343nullfs_vptofh(vp, fhp) 344 struct vnode *vp; 345 struct fid *fhp; 346{ 347 struct vnode *lvp; 348 349 lvp = NULLVPTOLOWERVP(vp); 350 return VFS_VPTOFH(lvp, fhp); 351} 352 353static int 354nullfs_extattrctl(mp, cmd, filename_vp, namespace, attrname, td) 355 struct mount *mp; 356 int cmd; 357 struct vnode *filename_vp; 358 int namespace; 359 const char *attrname; 360 struct thread *td; 361{ 362 return VFS_EXTATTRCTL(MOUNTTONULLMOUNT(mp)->nullm_vfs, cmd, filename_vp, 363 namespace, attrname, td); 364} 365 366 367static struct vfsops null_vfsops = { 368 .vfs_extattrctl = nullfs_extattrctl, 369 .vfs_fhtovp = nullfs_fhtovp, 370 .vfs_init = nullfs_init, 371 .vfs_mount = nullfs_mount, 372 .vfs_quotactl = nullfs_quotactl, 373 .vfs_root = nullfs_root, 374 .vfs_statfs = nullfs_statfs, 375 .vfs_sync = nullfs_sync, 376 .vfs_uninit = nullfs_uninit, 377 .vfs_unmount = nullfs_unmount, 378 .vfs_vget = nullfs_vget, 379 .vfs_vptofh = nullfs_vptofh, 380}; 381 382VFS_SET(null_vfsops, nullfs, VFCF_LOOPBACK); 383