null_vfsops.c revision 232301
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 232301 2012-02-29 15:09:20Z kib $ 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/fcntl.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#include <sys/jail.h> 54 55#include <fs/nullfs/null.h> 56 57static MALLOC_DEFINE(M_NULLFSMNT, "nullfs_mount", "NULLFS mount structure"); 58 59static vfs_fhtovp_t nullfs_fhtovp; 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_extattrctl_t nullfs_extattrctl; 68 69/* 70 * Mount null layer 71 */ 72static int 73nullfs_mount(struct mount *mp) 74{ 75 int error = 0; 76 struct vnode *lowerrootvp, *vp; 77 struct vnode *nullm_rootvp; 78 struct null_mount *xmp; 79 struct thread *td = curthread; 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 (!prison_allow(td->td_ucred, PR_ALLOW_MOUNT_NULLFS)) 87 return (EPERM); 88 89 if (mp->mnt_flag & MNT_ROOTFS) 90 return (EOPNOTSUPP); 91 /* 92 * Update is a no-op 93 */ 94 if (mp->mnt_flag & MNT_UPDATE) { 95 /* 96 * Only support update mounts for NFS export. 97 */ 98 if (vfs_flagopt(mp->mnt_optnew, "export", NULL, 0)) 99 return (0); 100 else 101 return (EOPNOTSUPP); 102 } 103 104 /* 105 * Get argument 106 */ 107 error = vfs_getopt(mp->mnt_optnew, "target", (void **)&target, &len); 108 if (error || target[len - 1] != '\0') 109 return (EINVAL); 110 111 /* 112 * Unlock lower node to avoid possible deadlock. 113 */ 114 if ((mp->mnt_vnodecovered->v_op == &null_vnodeops) && 115 VOP_ISLOCKED(mp->mnt_vnodecovered) == LK_EXCLUSIVE) { 116 VOP_UNLOCK(mp->mnt_vnodecovered, 0); 117 isvnunlocked = 1; 118 } 119 /* 120 * Find lower node 121 */ 122 NDINIT(ndp, LOOKUP, FOLLOW|LOCKLEAF, UIO_SYSSPACE, target, curthread); 123 error = namei(ndp); 124 /* 125 * Re-lock vnode. 126 */ 127 if (isvnunlocked) 128 vn_lock(mp->mnt_vnodecovered, LK_EXCLUSIVE | LK_RETRY); 129 130 if (error) 131 return (error); 132 NDFREE(ndp, NDF_ONLY_PNBUF); 133 134 /* 135 * Sanity check on lower vnode 136 */ 137 lowerrootvp = ndp->ni_vp; 138 139 /* 140 * Check multi null mount to avoid `lock against myself' panic. 141 */ 142 if (lowerrootvp == VTONULL(mp->mnt_vnodecovered)->null_lowervp) { 143 NULLFSDEBUG("nullfs_mount: multi null mount?\n"); 144 vput(lowerrootvp); 145 return (EDEADLK); 146 } 147 148 xmp = (struct null_mount *) malloc(sizeof(struct null_mount), 149 M_NULLFSMNT, M_WAITOK); /* XXX */ 150 151 /* 152 * Save reference to underlying FS 153 */ 154 xmp->nullm_vfs = lowerrootvp->v_mount; 155 156 /* 157 * Save reference. Each mount also holds 158 * a reference on the root vnode. 159 */ 160 error = null_nodeget(mp, lowerrootvp, &vp); 161 /* 162 * Make sure the node alias worked 163 */ 164 if (error) { 165 free(xmp, M_NULLFSMNT); 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); 181 182 if (NULLVPTOLOWERVP(nullm_rootvp)->v_mount->mnt_flag & MNT_LOCAL) { 183 MNT_ILOCK(mp); 184 mp->mnt_flag |= MNT_LOCAL; 185 MNT_IUNLOCK(mp); 186 } 187 MNT_ILOCK(mp); 188 mp->mnt_kern_flag |= lowerrootvp->v_mount->mnt_kern_flag & MNTK_MPSAFE; 189 MNT_IUNLOCK(mp); 190 mp->mnt_data = xmp; 191 vfs_getnewfsid(mp); 192 193 vfs_mountedfrom(mp, target); 194 195 NULLFSDEBUG("nullfs_mount: lower %s, alias at %s\n", 196 mp->mnt_stat.f_mntfromname, mp->mnt_stat.f_mntonname); 197 return (0); 198} 199 200/* 201 * Free reference to null layer 202 */ 203static int 204nullfs_unmount(mp, mntflags) 205 struct mount *mp; 206 int mntflags; 207{ 208 void *mntdata; 209 int error; 210 int flags = 0; 211 212 NULLFSDEBUG("nullfs_unmount: mp = %p\n", (void *)mp); 213 214 if (mntflags & MNT_FORCE) 215 flags |= FORCECLOSE; 216 217 /* There is 1 extra root vnode reference (nullm_rootvp). */ 218 error = vflush(mp, 1, flags, curthread); 219 if (error) 220 return (error); 221 222 /* 223 * Finally, throw away the null_mount structure 224 */ 225 mntdata = mp->mnt_data; 226 mp->mnt_data = 0; 227 free(mntdata, M_NULLFSMNT); 228 return 0; 229} 230 231static int 232nullfs_root(mp, flags, vpp) 233 struct mount *mp; 234 int flags; 235 struct vnode **vpp; 236{ 237 struct vnode *vp; 238 239 NULLFSDEBUG("nullfs_root(mp = %p, vp = %p->%p)\n", (void *)mp, 240 (void *)MOUNTTONULLMOUNT(mp)->nullm_rootvp, 241 (void *)NULLVPTOLOWERVP(MOUNTTONULLMOUNT(mp)->nullm_rootvp)); 242 243 /* 244 * Return locked reference to root. 245 */ 246 vp = MOUNTTONULLMOUNT(mp)->nullm_rootvp; 247 VREF(vp); 248 249 ASSERT_VOP_UNLOCKED(vp, "root vnode is locked"); 250 vn_lock(vp, flags | LK_RETRY); 251 *vpp = vp; 252 return 0; 253} 254 255static int 256nullfs_quotactl(mp, cmd, uid, arg) 257 struct mount *mp; 258 int cmd; 259 uid_t uid; 260 void *arg; 261{ 262 return VFS_QUOTACTL(MOUNTTONULLMOUNT(mp)->nullm_vfs, cmd, uid, arg); 263} 264 265static int 266nullfs_statfs(mp, sbp) 267 struct mount *mp; 268 struct statfs *sbp; 269{ 270 int error; 271 struct statfs mstat; 272 273 NULLFSDEBUG("nullfs_statfs(mp = %p, vp = %p->%p)\n", (void *)mp, 274 (void *)MOUNTTONULLMOUNT(mp)->nullm_rootvp, 275 (void *)NULLVPTOLOWERVP(MOUNTTONULLMOUNT(mp)->nullm_rootvp)); 276 277 bzero(&mstat, sizeof(mstat)); 278 279 error = VFS_STATFS(MOUNTTONULLMOUNT(mp)->nullm_vfs, &mstat); 280 if (error) 281 return (error); 282 283 /* now copy across the "interesting" information and fake the rest */ 284 sbp->f_type = mstat.f_type; 285 sbp->f_flags = mstat.f_flags; 286 sbp->f_bsize = mstat.f_bsize; 287 sbp->f_iosize = mstat.f_iosize; 288 sbp->f_blocks = mstat.f_blocks; 289 sbp->f_bfree = mstat.f_bfree; 290 sbp->f_bavail = mstat.f_bavail; 291 sbp->f_files = mstat.f_files; 292 sbp->f_ffree = mstat.f_ffree; 293 return (0); 294} 295 296static int 297nullfs_sync(mp, waitfor) 298 struct mount *mp; 299 int waitfor; 300{ 301 /* 302 * XXX - Assumes no data cached at null layer. 303 */ 304 return (0); 305} 306 307static int 308nullfs_vget(mp, ino, flags, vpp) 309 struct mount *mp; 310 ino_t ino; 311 int flags; 312 struct vnode **vpp; 313{ 314 int error; 315 316 KASSERT((flags & LK_TYPE_MASK) != 0, 317 ("nullfs_vget: no lock requested")); 318 flags &= ~LK_TYPE_MASK; 319 flags |= LK_EXCLUSIVE; 320 321 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, flags, vpp) 330 struct mount *mp; 331 struct fid *fidp; 332 int flags; 333 struct vnode **vpp; 334{ 335 int error; 336 error = VFS_FHTOVP(MOUNTTONULLMOUNT(mp)->nullm_vfs, fidp, LK_EXCLUSIVE, 337 vpp); 338 if (error) 339 return (error); 340 341 return (null_nodeget(mp, *vpp, vpp)); 342} 343 344static int 345nullfs_extattrctl(mp, cmd, filename_vp, namespace, attrname) 346 struct mount *mp; 347 int cmd; 348 struct vnode *filename_vp; 349 int namespace; 350 const char *attrname; 351{ 352 return VFS_EXTATTRCTL(MOUNTTONULLMOUNT(mp)->nullm_vfs, cmd, filename_vp, 353 namespace, attrname); 354} 355 356 357static struct vfsops null_vfsops = { 358 .vfs_extattrctl = nullfs_extattrctl, 359 .vfs_fhtovp = nullfs_fhtovp, 360 .vfs_init = nullfs_init, 361 .vfs_mount = nullfs_mount, 362 .vfs_quotactl = nullfs_quotactl, 363 .vfs_root = nullfs_root, 364 .vfs_statfs = nullfs_statfs, 365 .vfs_sync = nullfs_sync, 366 .vfs_uninit = nullfs_uninit, 367 .vfs_unmount = nullfs_unmount, 368 .vfs_vget = nullfs_vget, 369}; 370 371VFS_SET(null_vfsops, nullfs, VFCF_LOOPBACK | VFCF_JAIL); 372