null_vfsops.c revision 232918
1264790Sbapt/*- 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 232918 2012-03-13 10:04:13Z kevlo $ 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 & 189 (MNTK_MPSAFE | MNTK_SHARED_WRITES); 190 MNT_IUNLOCK(mp); 191 mp->mnt_data = xmp; 192 vfs_getnewfsid(mp); 193 194 vfs_mountedfrom(mp, target); 195 196 NULLFSDEBUG("nullfs_mount: lower %s, alias at %s\n", 197 mp->mnt_stat.f_mntfromname, mp->mnt_stat.f_mntonname); 198 return (0); 199} 200 201/* 202 * Free reference to null layer 203 */ 204static int 205nullfs_unmount(mp, mntflags) 206 struct mount *mp; 207 int mntflags; 208{ 209 void *mntdata; 210 int error; 211 int flags = 0; 212 213 NULLFSDEBUG("nullfs_unmount: mp = %p\n", (void *)mp); 214 215 if (mntflags & MNT_FORCE) 216 flags |= FORCECLOSE; 217 218 /* There is 1 extra root vnode reference (nullm_rootvp). */ 219 error = vflush(mp, 1, flags, curthread); 220 if (error) 221 return (error); 222 223 /* 224 * Finally, throw away the null_mount structure 225 */ 226 mntdata = mp->mnt_data; 227 mp->mnt_data = NULL; 228 free(mntdata, M_NULLFSMNT); 229 return 0; 230} 231 232static int 233nullfs_root(mp, flags, vpp) 234 struct mount *mp; 235 int flags; 236 struct vnode **vpp; 237{ 238 struct vnode *vp; 239 240 NULLFSDEBUG("nullfs_root(mp = %p, vp = %p->%p)\n", (void *)mp, 241 (void *)MOUNTTONULLMOUNT(mp)->nullm_rootvp, 242 (void *)NULLVPTOLOWERVP(MOUNTTONULLMOUNT(mp)->nullm_rootvp)); 243 244 /* 245 * Return locked reference to root. 246 */ 247 vp = MOUNTTONULLMOUNT(mp)->nullm_rootvp; 248 VREF(vp); 249 250 ASSERT_VOP_UNLOCKED(vp, "root vnode is locked"); 251 vn_lock(vp, flags | LK_RETRY); 252 *vpp = vp; 253 return 0; 254} 255 256static int 257nullfs_quotactl(mp, cmd, uid, arg) 258 struct mount *mp; 259 int cmd; 260 uid_t uid; 261 void *arg; 262{ 263 return VFS_QUOTACTL(MOUNTTONULLMOUNT(mp)->nullm_vfs, cmd, uid, arg); 264} 265 266static int 267nullfs_statfs(mp, sbp) 268 struct mount *mp; 269 struct statfs *sbp; 270{ 271 int error; 272 struct statfs mstat; 273 274 NULLFSDEBUG("nullfs_statfs(mp = %p, vp = %p->%p)\n", (void *)mp, 275 (void *)MOUNTTONULLMOUNT(mp)->nullm_rootvp, 276 (void *)NULLVPTOLOWERVP(MOUNTTONULLMOUNT(mp)->nullm_rootvp)); 277 278 bzero(&mstat, sizeof(mstat)); 279 280 error = VFS_STATFS(MOUNTTONULLMOUNT(mp)->nullm_vfs, &mstat); 281 if (error) 282 return (error); 283 284 /* now copy across the "interesting" information and fake the rest */ 285 sbp->f_type = mstat.f_type; 286 sbp->f_flags = mstat.f_flags; 287 sbp->f_bsize = mstat.f_bsize; 288 sbp->f_iosize = mstat.f_iosize; 289 sbp->f_blocks = mstat.f_blocks; 290 sbp->f_bfree = mstat.f_bfree; 291 sbp->f_bavail = mstat.f_bavail; 292 sbp->f_files = mstat.f_files; 293 sbp->f_ffree = mstat.f_ffree; 294 return (0); 295} 296 297static int 298nullfs_sync(mp, waitfor) 299 struct mount *mp; 300 int waitfor; 301{ 302 /* 303 * XXX - Assumes no data cached at null layer. 304 */ 305 return (0); 306} 307 308static int 309nullfs_vget(mp, ino, flags, vpp) 310 struct mount *mp; 311 ino_t ino; 312 int flags; 313 struct vnode **vpp; 314{ 315 int error; 316 317 KASSERT((flags & LK_TYPE_MASK) != 0, 318 ("nullfs_vget: no lock requested")); 319 flags &= ~LK_TYPE_MASK; 320 flags |= LK_EXCLUSIVE; 321 322 error = VFS_VGET(MOUNTTONULLMOUNT(mp)->nullm_vfs, ino, flags, vpp); 323 if (error) 324 return (error); 325 326 return (null_nodeget(mp, *vpp, vpp)); 327} 328 329static int 330nullfs_fhtovp(mp, fidp, flags, vpp) 331 struct mount *mp; 332 struct fid *fidp; 333 int flags; 334 struct vnode **vpp; 335{ 336 int error; 337 error = VFS_FHTOVP(MOUNTTONULLMOUNT(mp)->nullm_vfs, fidp, LK_EXCLUSIVE, 338 vpp); 339 if (error) 340 return (error); 341 342 return (null_nodeget(mp, *vpp, vpp)); 343} 344 345static int 346nullfs_extattrctl(mp, cmd, filename_vp, namespace, attrname) 347 struct mount *mp; 348 int cmd; 349 struct vnode *filename_vp; 350 int namespace; 351 const char *attrname; 352{ 353 return VFS_EXTATTRCTL(MOUNTTONULLMOUNT(mp)->nullm_vfs, cmd, filename_vp, 354 namespace, attrname); 355} 356 357 358static struct vfsops null_vfsops = { 359 .vfs_extattrctl = nullfs_extattrctl, 360 .vfs_fhtovp = nullfs_fhtovp, 361 .vfs_init = nullfs_init, 362 .vfs_mount = nullfs_mount, 363 .vfs_quotactl = nullfs_quotactl, 364 .vfs_root = nullfs_root, 365 .vfs_statfs = nullfs_statfs, 366 .vfs_sync = nullfs_sync, 367 .vfs_uninit = nullfs_uninit, 368 .vfs_unmount = nullfs_unmount, 369 .vfs_vget = nullfs_vget, 370}; 371 372VFS_SET(null_vfsops, nullfs, VFCF_LOOPBACK | VFCF_JAIL); 373