Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)
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FreeBSD/Linux Kernel Cross Reference
sys/fs/nullfs/null_vfsops.c
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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 * $FreeBSD$ 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 57 static MALLOC_DEFINE(M_NULLFSMNT, "nullfs_mount", "NULLFS mount structure"); 58 59 static vfs_fhtovp_t nullfs_fhtovp; 60 static vfs_mount_t nullfs_mount; 61 static vfs_quotactl_t nullfs_quotactl; 62 static vfs_root_t nullfs_root; 63 static vfs_sync_t nullfs_sync; 64 static vfs_statfs_t nullfs_statfs; 65 static vfs_unmount_t nullfs_unmount; 66 static vfs_vget_t nullfs_vget; 67 static vfs_extattrctl_t nullfs_extattrctl; 68 69 /* 70 * Mount null layer 71 */ 72 static int 73 nullfs_mount(struct mount *mp) 74 { 75 struct vnode *lowerrootvp; 76 struct vnode *nullm_rootvp; 77 struct null_mount *xmp; 78 struct thread *td = curthread; 79 struct null_node *nn; 80 struct nameidata nd, *ndp; 81 char *target; 82 int error, len; 83 bool isvnunlocked; 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 = true; 119 } else { 120 isvnunlocked = false; 121 } 122 123 /* 124 * Find lower node 125 */ 126 ndp = &nd; 127 NDINIT(ndp, LOOKUP, FOLLOW|LOCKLEAF, UIO_SYSSPACE, target, curthread); 128 error = namei(ndp); 129 130 /* 131 * Re-lock vnode. 132 * XXXKIB This is deadlock-prone as well. 133 */ 134 if (isvnunlocked) 135 vn_lock(mp->mnt_vnodecovered, LK_EXCLUSIVE | LK_RETRY); 136 137 if (error) 138 return (error); 139 NDFREE(ndp, NDF_ONLY_PNBUF); 140 141 /* 142 * Sanity check on lower vnode 143 */ 144 lowerrootvp = ndp->ni_vp; 145 146 /* 147 * Check multi null mount to avoid `lock against myself' panic. 148 */ 149 if (mp->mnt_vnodecovered->v_op == &null_vnodeops) { 150 nn = VTONULL(mp->mnt_vnodecovered); 151 if (nn == NULL || lowerrootvp == nn->null_lowervp) { 152 NULLFSDEBUG("nullfs_mount: multi null mount?\n"); 153 vput(lowerrootvp); 154 return (EDEADLK); 155 } 156 } 157 158 xmp = (struct null_mount *) malloc(sizeof(struct null_mount), 159 M_NULLFSMNT, M_WAITOK | M_ZERO); 160 161 /* 162 * Save pointer to underlying FS and the reference to the 163 * lower root vnode. 164 */ 165 xmp->nullm_vfs = lowerrootvp->v_mount; 166 vref(lowerrootvp); 167 xmp->nullm_lowerrootvp = lowerrootvp; 168 mp->mnt_data = xmp; 169 170 /* 171 * Make sure the node alias worked. 172 */ 173 error = null_nodeget(mp, lowerrootvp, &nullm_rootvp); 174 if (error != 0) { 175 vrele(lowerrootvp); 176 free(xmp, M_NULLFSMNT); 177 return (error); 178 } 179 180 if (NULLVPTOLOWERVP(nullm_rootvp)->v_mount->mnt_flag & MNT_LOCAL) { 181 MNT_ILOCK(mp); 182 mp->mnt_flag |= MNT_LOCAL; 183 MNT_IUNLOCK(mp); 184 } 185 186 xmp->nullm_flags |= NULLM_CACHE; 187 if (vfs_getopt(mp->mnt_optnew, "nocache", NULL, NULL) == 0 || 188 (xmp->nullm_vfs->mnt_kern_flag & MNTK_NULL_NOCACHE) != 0) 189 xmp->nullm_flags &= ~NULLM_CACHE; 190 191 MNT_ILOCK(mp); 192 if ((xmp->nullm_flags & NULLM_CACHE) != 0) { 193 mp->mnt_kern_flag |= lowerrootvp->v_mount->mnt_kern_flag & 194 (MNTK_SHARED_WRITES | MNTK_LOOKUP_SHARED | 195 MNTK_EXTENDED_SHARED); 196 } 197 mp->mnt_kern_flag |= MNTK_LOOKUP_EXCL_DOTDOT; 198 mp->mnt_kern_flag |= lowerrootvp->v_mount->mnt_kern_flag & 199 (MNTK_USES_BCACHE | MNTK_NO_IOPF | MNTK_UNMAPPED_BUFS); 200 MNT_IUNLOCK(mp); 201 vfs_getnewfsid(mp); 202 if ((xmp->nullm_flags & NULLM_CACHE) != 0) { 203 MNT_ILOCK(xmp->nullm_vfs); 204 TAILQ_INSERT_TAIL(&xmp->nullm_vfs->mnt_uppers, mp, 205 mnt_upper_link); 206 MNT_IUNLOCK(xmp->nullm_vfs); 207 } 208 209 vfs_mountedfrom(mp, target); 210 vput(nullm_rootvp); 211 212 NULLFSDEBUG("nullfs_mount: lower %s, alias at %s\n", 213 mp->mnt_stat.f_mntfromname, mp->mnt_stat.f_mntonname); 214 return (0); 215 } 216 217 /* 218 * Free reference to null layer 219 */ 220 static int 221 nullfs_unmount(mp, mntflags) 222 struct mount *mp; 223 int mntflags; 224 { 225 struct null_mount *mntdata; 226 struct mount *ump; 227 int error, flags; 228 229 NULLFSDEBUG("nullfs_unmount: mp = %p\n", (void *)mp); 230 231 if (mntflags & MNT_FORCE) 232 flags = FORCECLOSE; 233 else 234 flags = 0; 235 236 for (;;) { 237 /* There is 1 extra root vnode reference (nullm_rootvp). */ 238 error = vflush(mp, 0, flags, curthread); 239 if (error) 240 return (error); 241 MNT_ILOCK(mp); 242 if (mp->mnt_nvnodelistsize == 0) { 243 MNT_IUNLOCK(mp); 244 break; 245 } 246 MNT_IUNLOCK(mp); 247 if ((mntflags & MNT_FORCE) == 0) 248 return (EBUSY); 249 } 250 251 /* 252 * Finally, throw away the null_mount structure 253 */ 254 mntdata = mp->mnt_data; 255 ump = mntdata->nullm_vfs; 256 if ((mntdata->nullm_flags & NULLM_CACHE) != 0) { 257 MNT_ILOCK(ump); 258 while ((ump->mnt_kern_flag & MNTK_VGONE_UPPER) != 0) { 259 ump->mnt_kern_flag |= MNTK_VGONE_WAITER; 260 msleep(&ump->mnt_uppers, &ump->mnt_mtx, 0, "vgnupw", 0); 261 } 262 TAILQ_REMOVE(&ump->mnt_uppers, mp, mnt_upper_link); 263 MNT_IUNLOCK(ump); 264 } 265 vrele(mntdata->nullm_lowerrootvp); 266 mp->mnt_data = NULL; 267 free(mntdata, M_NULLFSMNT); 268 return (0); 269 } 270 271 static int 272 nullfs_root(mp, flags, vpp) 273 struct mount *mp; 274 int flags; 275 struct vnode **vpp; 276 { 277 struct vnode *vp; 278 struct null_mount *mntdata; 279 int error; 280 281 mntdata = MOUNTTONULLMOUNT(mp); 282 NULLFSDEBUG("nullfs_root(mp = %p, vp = %p)\n", mp, 283 mntdata->nullm_lowerrootvp); 284 285 error = vget(mntdata->nullm_lowerrootvp, (flags & ~LK_TYPE_MASK) | 286 LK_EXCLUSIVE, curthread); 287 if (error == 0) { 288 error = null_nodeget(mp, mntdata->nullm_lowerrootvp, &vp); 289 if (error == 0) { 290 if ((flags & LK_TYPE_MASK) == LK_SHARED) 291 vn_lock(vp, LK_DOWNGRADE | LK_RETRY); 292 *vpp = vp; 293 } 294 } 295 return (error); 296 } 297 298 static int 299 nullfs_quotactl(mp, cmd, uid, arg) 300 struct mount *mp; 301 int cmd; 302 uid_t uid; 303 void *arg; 304 { 305 return VFS_QUOTACTL(MOUNTTONULLMOUNT(mp)->nullm_vfs, cmd, uid, arg); 306 } 307 308 static int 309 nullfs_statfs(mp, sbp) 310 struct mount *mp; 311 struct statfs *sbp; 312 { 313 int error; 314 struct statfs *mstat; 315 316 NULLFSDEBUG("nullfs_statfs(mp = %p, vp = %p->%p)\n", (void *)mp, 317 (void *)MOUNTTONULLMOUNT(mp)->nullm_rootvp, 318 (void *)NULLVPTOLOWERVP(MOUNTTONULLMOUNT(mp)->nullm_rootvp)); 319 320 mstat = malloc(sizeof(struct statfs), M_STATFS, M_WAITOK | M_ZERO); 321 322 error = VFS_STATFS(MOUNTTONULLMOUNT(mp)->nullm_vfs, mstat); 323 if (error) { 324 free(mstat, M_STATFS); 325 return (error); 326 } 327 328 /* now copy across the "interesting" information and fake the rest */ 329 sbp->f_type = mstat->f_type; 330 sbp->f_flags = (sbp->f_flags & (MNT_RDONLY | MNT_NOEXEC | MNT_NOSUID | 331 MNT_UNION | MNT_NOSYMFOLLOW | MNT_AUTOMOUNTED)) | 332 (mstat->f_flags & ~(MNT_ROOTFS | MNT_AUTOMOUNTED)); 333 sbp->f_bsize = mstat->f_bsize; 334 sbp->f_iosize = mstat->f_iosize; 335 sbp->f_blocks = mstat->f_blocks; 336 sbp->f_bfree = mstat->f_bfree; 337 sbp->f_bavail = mstat->f_bavail; 338 sbp->f_files = mstat->f_files; 339 sbp->f_ffree = mstat->f_ffree; 340 341 free(mstat, M_STATFS); 342 return (0); 343 } 344 345 static int 346 nullfs_sync(mp, waitfor) 347 struct mount *mp; 348 int waitfor; 349 { 350 /* 351 * XXX - Assumes no data cached at null layer. 352 */ 353 return (0); 354 } 355 356 static int 357 nullfs_vget(mp, ino, flags, vpp) 358 struct mount *mp; 359 ino_t ino; 360 int flags; 361 struct vnode **vpp; 362 { 363 int error; 364 365 KASSERT((flags & LK_TYPE_MASK) != 0, 366 ("nullfs_vget: no lock requested")); 367 368 error = VFS_VGET(MOUNTTONULLMOUNT(mp)->nullm_vfs, ino, flags, vpp); 369 if (error != 0) 370 return (error); 371 return (null_nodeget(mp, *vpp, vpp)); 372 } 373 374 static int 375 nullfs_fhtovp(mp, fidp, flags, vpp) 376 struct mount *mp; 377 struct fid *fidp; 378 int flags; 379 struct vnode **vpp; 380 { 381 int error; 382 383 error = VFS_FHTOVP(MOUNTTONULLMOUNT(mp)->nullm_vfs, fidp, flags, 384 vpp); 385 if (error != 0) 386 return (error); 387 return (null_nodeget(mp, *vpp, vpp)); 388 } 389 390 static int 391 nullfs_extattrctl(mp, cmd, filename_vp, namespace, attrname) 392 struct mount *mp; 393 int cmd; 394 struct vnode *filename_vp; 395 int namespace; 396 const char *attrname; 397 { 398 399 return (VFS_EXTATTRCTL(MOUNTTONULLMOUNT(mp)->nullm_vfs, cmd, 400 filename_vp, namespace, attrname)); 401 } 402 403 static void 404 nullfs_reclaim_lowervp(struct mount *mp, struct vnode *lowervp) 405 { 406 struct vnode *vp; 407 408 vp = null_hashget(mp, lowervp); 409 if (vp == NULL) 410 return; 411 VTONULL(vp)->null_flags |= NULLV_NOUNLOCK; 412 vgone(vp); 413 vput(vp); 414 } 415 416 static void 417 nullfs_unlink_lowervp(struct mount *mp, struct vnode *lowervp) 418 { 419 struct vnode *vp; 420 struct null_node *xp; 421 422 vp = null_hashget(mp, lowervp); 423 if (vp == NULL) 424 return; 425 xp = VTONULL(vp); 426 xp->null_flags |= NULLV_DROP | NULLV_NOUNLOCK; 427 vhold(vp); 428 vunref(vp); 429 430 if (vp->v_usecount == 0) { 431 /* 432 * If vunref() dropped the last use reference on the 433 * nullfs vnode, it must be reclaimed, and its lock 434 * was split from the lower vnode lock. Need to do 435 * extra unlock before allowing the final vdrop() to 436 * free the vnode. 437 */ 438 KASSERT((vp->v_iflag & VI_DOOMED) != 0, 439 ("not reclaimed nullfs vnode %p", vp)); 440 VOP_UNLOCK(vp, 0); 441 } else { 442 /* 443 * Otherwise, the nullfs vnode still shares the lock 444 * with the lower vnode, and must not be unlocked. 445 * Also clear the NULLV_NOUNLOCK, the flag is not 446 * relevant for future reclamations. 447 */ 448 ASSERT_VOP_ELOCKED(vp, "unlink_lowervp"); 449 KASSERT((vp->v_iflag & VI_DOOMED) == 0, 450 ("reclaimed nullfs vnode %p", vp)); 451 xp->null_flags &= ~NULLV_NOUNLOCK; 452 } 453 vdrop(vp); 454 } 455 456 static struct vfsops null_vfsops = { 457 .vfs_extattrctl = nullfs_extattrctl, 458 .vfs_fhtovp = nullfs_fhtovp, 459 .vfs_init = nullfs_init, 460 .vfs_mount = nullfs_mount, 461 .vfs_quotactl = nullfs_quotactl, 462 .vfs_root = nullfs_root, 463 .vfs_statfs = nullfs_statfs, 464 .vfs_sync = nullfs_sync, 465 .vfs_uninit = nullfs_uninit, 466 .vfs_unmount = nullfs_unmount, 467 .vfs_vget = nullfs_vget, 468 .vfs_reclaim_lowervp = nullfs_reclaim_lowervp, 469 .vfs_unlink_lowervp = nullfs_unlink_lowervp, 470 }; 471 472 VFS_SET(null_vfsops, nullfs, VFCF_LOOPBACK | VFCF_JAIL);
Cache object: 19f0546104f7c6c5936d89f6f47d54f4
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