null_vfsops.c revision 247619
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 247619 2013-03-02 12:42:23Z jilles $ 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; 68static vfs_reclaim_lowervp_t nullfs_reclaim_lowervp; 69 70/* 71 * Mount null layer 72 */ 73static int 74nullfs_mount(struct mount *mp) 75{ 76 int error = 0; 77 struct vnode *lowerrootvp, *vp; 78 struct vnode *nullm_rootvp; 79 struct null_mount *xmp; 80 struct thread *td = curthread; 81 char *target; 82 int isvnunlocked = 0, len; 83 struct nameidata nd, *ndp = &nd; 84 85 NULLFSDEBUG("nullfs_mount(mp = %p)\n", (void *)mp); 86 87 if (!prison_allow(td->td_ucred, PR_ALLOW_MOUNT_NULLFS)) 88 return (EPERM); 89 if (mp->mnt_flag & MNT_ROOTFS) 90 return (EOPNOTSUPP); 91 92 /* 93 * Update is a no-op 94 */ 95 if (mp->mnt_flag & MNT_UPDATE) { 96 /* 97 * Only support update mounts for NFS export. 98 */ 99 if (vfs_flagopt(mp->mnt_optnew, "export", NULL, 0)) 100 return (0); 101 else 102 return (EOPNOTSUPP); 103 } 104 105 /* 106 * Get argument 107 */ 108 error = vfs_getopt(mp->mnt_optnew, "target", (void **)&target, &len); 109 if (error || target[len - 1] != '\0') 110 return (EINVAL); 111 112 /* 113 * Unlock lower node to avoid possible deadlock. 114 */ 115 if ((mp->mnt_vnodecovered->v_op == &null_vnodeops) && 116 VOP_ISLOCKED(mp->mnt_vnodecovered) == LK_EXCLUSIVE) { 117 VOP_UNLOCK(mp->mnt_vnodecovered, 0); 118 isvnunlocked = 1; 119 } 120 /* 121 * Find lower node 122 */ 123 NDINIT(ndp, LOOKUP, FOLLOW|LOCKLEAF, UIO_SYSSPACE, target, curthread); 124 error = namei(ndp); 125 126 /* 127 * Re-lock vnode. 128 * XXXKIB This is deadlock-prone as well. 129 */ 130 if (isvnunlocked) 131 vn_lock(mp->mnt_vnodecovered, LK_EXCLUSIVE | LK_RETRY); 132 133 if (error) 134 return (error); 135 NDFREE(ndp, NDF_ONLY_PNBUF); 136 137 /* 138 * Sanity check on lower vnode 139 */ 140 lowerrootvp = ndp->ni_vp; 141 142 /* 143 * Check multi null mount to avoid `lock against myself' panic. 144 */ 145 if (lowerrootvp == VTONULL(mp->mnt_vnodecovered)->null_lowervp) { 146 NULLFSDEBUG("nullfs_mount: multi null mount?\n"); 147 vput(lowerrootvp); 148 return (EDEADLK); 149 } 150 151 xmp = (struct null_mount *) malloc(sizeof(struct null_mount), 152 M_NULLFSMNT, M_WAITOK | M_ZERO); 153 154 /* 155 * Save reference to underlying FS 156 */ 157 xmp->nullm_vfs = lowerrootvp->v_mount; 158 159 /* 160 * Save reference. Each mount also holds 161 * a reference on the root vnode. 162 */ 163 error = null_nodeget(mp, lowerrootvp, &vp); 164 /* 165 * Make sure the node alias worked 166 */ 167 if (error) { 168 free(xmp, M_NULLFSMNT); 169 return (error); 170 } 171 172 /* 173 * Keep a held reference to the root vnode. 174 * It is vrele'd in nullfs_unmount. 175 */ 176 nullm_rootvp = vp; 177 nullm_rootvp->v_vflag |= VV_ROOT; 178 xmp->nullm_rootvp = nullm_rootvp; 179 180 /* 181 * Unlock the node (either the lower or the alias) 182 */ 183 VOP_UNLOCK(vp, 0); 184 185 if (NULLVPTOLOWERVP(nullm_rootvp)->v_mount->mnt_flag & MNT_LOCAL) { 186 MNT_ILOCK(mp); 187 mp->mnt_flag |= MNT_LOCAL; 188 MNT_IUNLOCK(mp); 189 } 190 191 xmp->nullm_flags |= NULLM_CACHE; 192 if (vfs_getopt(mp->mnt_optnew, "nocache", NULL, NULL) == 0) 193 xmp->nullm_flags &= ~NULLM_CACHE; 194 195 MNT_ILOCK(mp); 196 if ((xmp->nullm_flags & NULLM_CACHE) != 0) { 197 mp->mnt_kern_flag |= lowerrootvp->v_mount->mnt_kern_flag & 198 (MNTK_SHARED_WRITES | MNTK_LOOKUP_SHARED | 199 MNTK_EXTENDED_SHARED); 200 } 201 mp->mnt_kern_flag |= MNTK_LOOKUP_EXCL_DOTDOT; 202 MNT_IUNLOCK(mp); 203 mp->mnt_data = xmp; 204 vfs_getnewfsid(mp); 205 if ((xmp->nullm_flags & NULLM_CACHE) != 0) { 206 MNT_ILOCK(xmp->nullm_vfs); 207 TAILQ_INSERT_TAIL(&xmp->nullm_vfs->mnt_uppers, mp, 208 mnt_upper_link); 209 MNT_IUNLOCK(xmp->nullm_vfs); 210 } 211 212 vfs_mountedfrom(mp, target); 213 214 NULLFSDEBUG("nullfs_mount: lower %s, alias at %s\n", 215 mp->mnt_stat.f_mntfromname, mp->mnt_stat.f_mntonname); 216 return (0); 217} 218 219/* 220 * Free reference to null layer 221 */ 222static int 223nullfs_unmount(mp, mntflags) 224 struct mount *mp; 225 int mntflags; 226{ 227 struct null_mount *mntdata; 228 struct mount *ump; 229 int error, flags; 230 231 NULLFSDEBUG("nullfs_unmount: mp = %p\n", (void *)mp); 232 233 if (mntflags & MNT_FORCE) 234 flags = FORCECLOSE; 235 else 236 flags = 0; 237 238 /* There is 1 extra root vnode reference (nullm_rootvp). */ 239 error = vflush(mp, 1, flags, curthread); 240 if (error) 241 return (error); 242 243 /* 244 * Finally, throw away the null_mount structure 245 */ 246 mntdata = mp->mnt_data; 247 ump = mntdata->nullm_vfs; 248 if ((mntdata->nullm_flags & NULLM_CACHE) != 0) { 249 MNT_ILOCK(ump); 250 while ((ump->mnt_kern_flag & MNTK_VGONE_UPPER) != 0) { 251 ump->mnt_kern_flag |= MNTK_VGONE_WAITER; 252 msleep(&ump->mnt_uppers, &ump->mnt_mtx, 0, "vgnupw", 0); 253 } 254 TAILQ_REMOVE(&ump->mnt_uppers, mp, mnt_upper_link); 255 MNT_IUNLOCK(ump); 256 } 257 mp->mnt_data = NULL; 258 free(mntdata, M_NULLFSMNT); 259 return (0); 260} 261 262static int 263nullfs_root(mp, flags, vpp) 264 struct mount *mp; 265 int flags; 266 struct vnode **vpp; 267{ 268 struct vnode *vp; 269 270 NULLFSDEBUG("nullfs_root(mp = %p, vp = %p->%p)\n", (void *)mp, 271 (void *)MOUNTTONULLMOUNT(mp)->nullm_rootvp, 272 (void *)NULLVPTOLOWERVP(MOUNTTONULLMOUNT(mp)->nullm_rootvp)); 273 274 /* 275 * Return locked reference to root. 276 */ 277 vp = MOUNTTONULLMOUNT(mp)->nullm_rootvp; 278 VREF(vp); 279 280 ASSERT_VOP_UNLOCKED(vp, "root vnode is locked"); 281 vn_lock(vp, flags | LK_RETRY); 282 *vpp = vp; 283 return 0; 284} 285 286static int 287nullfs_quotactl(mp, cmd, uid, arg) 288 struct mount *mp; 289 int cmd; 290 uid_t uid; 291 void *arg; 292{ 293 return VFS_QUOTACTL(MOUNTTONULLMOUNT(mp)->nullm_vfs, cmd, uid, arg); 294} 295 296static int 297nullfs_statfs(mp, sbp) 298 struct mount *mp; 299 struct statfs *sbp; 300{ 301 int error; 302 struct statfs mstat; 303 304 NULLFSDEBUG("nullfs_statfs(mp = %p, vp = %p->%p)\n", (void *)mp, 305 (void *)MOUNTTONULLMOUNT(mp)->nullm_rootvp, 306 (void *)NULLVPTOLOWERVP(MOUNTTONULLMOUNT(mp)->nullm_rootvp)); 307 308 bzero(&mstat, sizeof(mstat)); 309 310 error = VFS_STATFS(MOUNTTONULLMOUNT(mp)->nullm_vfs, &mstat); 311 if (error) 312 return (error); 313 314 /* now copy across the "interesting" information and fake the rest */ 315 sbp->f_type = mstat.f_type; 316 sbp->f_flags = (sbp->f_flags & (MNT_RDONLY | MNT_NOEXEC | MNT_NOSUID | 317 MNT_UNION | MNT_NOSYMFOLLOW)) | (mstat.f_flags & ~MNT_ROOTFS); 318 sbp->f_bsize = mstat.f_bsize; 319 sbp->f_iosize = mstat.f_iosize; 320 sbp->f_blocks = mstat.f_blocks; 321 sbp->f_bfree = mstat.f_bfree; 322 sbp->f_bavail = mstat.f_bavail; 323 sbp->f_files = mstat.f_files; 324 sbp->f_ffree = mstat.f_ffree; 325 return (0); 326} 327 328static int 329nullfs_sync(mp, waitfor) 330 struct mount *mp; 331 int waitfor; 332{ 333 /* 334 * XXX - Assumes no data cached at null layer. 335 */ 336 return (0); 337} 338 339static int 340nullfs_vget(mp, ino, flags, vpp) 341 struct mount *mp; 342 ino_t ino; 343 int flags; 344 struct vnode **vpp; 345{ 346 int error; 347 348 KASSERT((flags & LK_TYPE_MASK) != 0, 349 ("nullfs_vget: no lock requested")); 350 351 error = VFS_VGET(MOUNTTONULLMOUNT(mp)->nullm_vfs, ino, flags, vpp); 352 if (error != 0) 353 return (error); 354 return (null_nodeget(mp, *vpp, vpp)); 355} 356 357static int 358nullfs_fhtovp(mp, fidp, flags, vpp) 359 struct mount *mp; 360 struct fid *fidp; 361 int flags; 362 struct vnode **vpp; 363{ 364 int error; 365 366 error = VFS_FHTOVP(MOUNTTONULLMOUNT(mp)->nullm_vfs, fidp, flags, 367 vpp); 368 if (error != 0) 369 return (error); 370 return (null_nodeget(mp, *vpp, vpp)); 371} 372 373static int 374nullfs_extattrctl(mp, cmd, filename_vp, namespace, attrname) 375 struct mount *mp; 376 int cmd; 377 struct vnode *filename_vp; 378 int namespace; 379 const char *attrname; 380{ 381 382 return (VFS_EXTATTRCTL(MOUNTTONULLMOUNT(mp)->nullm_vfs, cmd, 383 filename_vp, namespace, attrname)); 384} 385 386static void 387nullfs_reclaim_lowervp(struct mount *mp, struct vnode *lowervp) 388{ 389 struct vnode *vp; 390 391 vp = null_hashget(mp, lowervp); 392 if (vp == NULL) 393 return; 394 vgone(vp); 395 vn_lock(lowervp, LK_EXCLUSIVE | LK_RETRY); 396} 397 398static struct vfsops null_vfsops = { 399 .vfs_extattrctl = nullfs_extattrctl, 400 .vfs_fhtovp = nullfs_fhtovp, 401 .vfs_init = nullfs_init, 402 .vfs_mount = nullfs_mount, 403 .vfs_quotactl = nullfs_quotactl, 404 .vfs_root = nullfs_root, 405 .vfs_statfs = nullfs_statfs, 406 .vfs_sync = nullfs_sync, 407 .vfs_uninit = nullfs_uninit, 408 .vfs_unmount = nullfs_unmount, 409 .vfs_vget = nullfs_vget, 410 .vfs_reclaim_lowervp = nullfs_reclaim_lowervp, 411}; 412 413VFS_SET(null_vfsops, nullfs, VFCF_LOOPBACK | VFCF_JAIL); 414