null_vfsops.c revision 250852
1169689Skan/*- 2169689Skan * Copyright (c) 1992, 1993, 1995 3117395Skan * The Regents of the University of California. All rights reserved. 418334Speter * 5132718Skan * This code is derived from software donated to Berkeley by 618334Speter * Jan-Simon Pendry. 7132718Skan * 818334Speter * Redistribution and use in source and binary forms, with or without 918334Speter * modification, are permitted provided that the following conditions 1018334Speter * are met: 1118334Speter * 1. Redistributions of source code must retain the above copyright 12132718Skan * notice, this list of conditions and the following disclaimer. 1318334Speter * 2. Redistributions in binary form must reproduce the above copyright 1418334Speter * notice, this list of conditions and the following disclaimer in the 1518334Speter * documentation and/or other materials provided with the distribution. 1618334Speter * 4. Neither the name of the University nor the names of its contributors 1718334Speter * may be used to endorse or promote products derived from this software 18132718Skan * without specific prior written permission. 19169689Skan * 20169689Skan * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 2118334Speter * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22169689Skan * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23169689Skan * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 24169689Skan * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25169689Skan * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26169689Skan * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27169689Skan * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 2818334Speter * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29169689Skan * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30169689Skan * SUCH DAMAGE. 31169689Skan * 3218334Speter * @(#)null_vfsops.c 8.2 (Berkeley) 1/21/94 33169689Skan * 34169689Skan * @(#)lofs_vfsops.c 1.2 (Berkeley) 6/18/92 35169689Skan * $FreeBSD: head/sys/fs/nullfs/null_vfsops.c 250852 2013-05-21 11:31:56Z kib $ 36169689Skan */ 37169689Skan 38169689Skan/* 39169689Skan * Null Layer 40169689Skan * (See null_vnops.c for a description of what this does.) 41169689Skan */ 4218334Speter 43169689Skan#include <sys/param.h> 44169689Skan#include <sys/systm.h> 45169689Skan#include <sys/fcntl.h> 4618334Speter#include <sys/kernel.h> 47169689Skan#include <sys/lock.h> 48169689Skan#include <sys/malloc.h> 49169689Skan#include <sys/mount.h> 5018334Speter#include <sys/namei.h> 51169689Skan#include <sys/proc.h> 52169689Skan#include <sys/vnode.h> 53169689Skan#include <sys/jail.h> 5418334Speter 55169689Skan#include <fs/nullfs/null.h> 56169689Skan 57169689Skanstatic MALLOC_DEFINE(M_NULLFSMNT, "nullfs_mount", "NULLFS mount structure"); 5818334Speter 59169689Skanstatic vfs_fhtovp_t nullfs_fhtovp; 60169689Skanstatic vfs_mount_t nullfs_mount; 61169689Skanstatic vfs_quotactl_t nullfs_quotactl; 6218334Speterstatic vfs_root_t nullfs_root; 63169689Skanstatic vfs_sync_t nullfs_sync; 64169689Skanstatic vfs_statfs_t nullfs_statfs; 65169689Skanstatic vfs_unmount_t nullfs_unmount; 6618334Speterstatic vfs_vget_t nullfs_vget; 67169689Skanstatic vfs_extattrctl_t nullfs_extattrctl; 68169689Skan 69169689Skan/* 70169689Skan * Mount null layer 71169689Skan */ 72169689Skanstatic int 73169689Skannullfs_mount(struct mount *mp) 74169689Skan{ 75169689Skan int error = 0; 7618334Speter struct vnode *lowerrootvp, *vp; 77169689Skan struct vnode *nullm_rootvp; 78169689Skan struct null_mount *xmp; 79169689Skan struct thread *td = curthread; 80169689Skan char *target; 8118334Speter int isvnunlocked = 0, len; 82169689Skan struct nameidata nd, *ndp = &nd; 83169689Skan 84169689Skan NULLFSDEBUG("nullfs_mount(mp = %p)\n", (void *)mp); 85169689Skan 8618334Speter if (!prison_allow(td->td_ucred, PR_ALLOW_MOUNT_NULLFS)) 87169689Skan return (EPERM); 88169689Skan if (mp->mnt_flag & MNT_ROOTFS) 89169689Skan return (EOPNOTSUPP); 90169689Skan 91169689Skan /* 9218334Speter * Update is a no-op 93169689Skan */ 94169689Skan if (mp->mnt_flag & MNT_UPDATE) { 95169689Skan /* 96169689Skan * Only support update mounts for NFS export. 97169689Skan */ 98169689Skan if (vfs_flagopt(mp->mnt_optnew, "export", NULL, 0)) 99169689Skan return (0); 100169689Skan else 101169689Skan return (EOPNOTSUPP); 102169689Skan } 103169689Skan 104169689Skan /* 105169689Skan * Get argument 106169689Skan */ 107169689Skan error = vfs_getopt(mp->mnt_optnew, "target", (void **)&target, &len); 108169689Skan if (error || target[len - 1] != '\0') 109169689Skan return (EINVAL); 11018334Speter 111169689Skan /* 112169689Skan * Unlock lower node to avoid possible deadlock. 113169689Skan */ 114169689Skan if ((mp->mnt_vnodecovered->v_op == &null_vnodeops) && 115169689Skan VOP_ISLOCKED(mp->mnt_vnodecovered) == LK_EXCLUSIVE) { 116169689Skan VOP_UNLOCK(mp->mnt_vnodecovered, 0); 117169689Skan isvnunlocked = 1; 118169689Skan } 119169689Skan /* 120169689Skan * Find lower node 121169689Skan */ 122169689Skan NDINIT(ndp, LOOKUP, FOLLOW|LOCKLEAF, UIO_SYSSPACE, target, curthread); 123169689Skan error = namei(ndp); 12418334Speter 125169689Skan /* 126169689Skan * Re-lock vnode. 127169689Skan * XXXKIB This is deadlock-prone as well. 128169689Skan */ 129169689Skan if (isvnunlocked) 130169689Skan vn_lock(mp->mnt_vnodecovered, LK_EXCLUSIVE | LK_RETRY); 13118334Speter 132169689Skan if (error) 13318334Speter return (error); 134169689Skan NDFREE(ndp, NDF_ONLY_PNBUF); 135169689Skan 136169689Skan /* 13718334Speter * Sanity check on lower vnode 138169689Skan */ 139169689Skan lowerrootvp = ndp->ni_vp; 140169689Skan 14118334Speter /* 142169689Skan * Check multi null mount to avoid `lock against myself' panic. 143169689Skan */ 144169689Skan if (lowerrootvp == VTONULL(mp->mnt_vnodecovered)->null_lowervp) { 14518334Speter NULLFSDEBUG("nullfs_mount: multi null mount?\n"); 146169689Skan vput(lowerrootvp); 147169689Skan return (EDEADLK); 148169689Skan } 14918334Speter 150169689Skan xmp = (struct null_mount *) malloc(sizeof(struct null_mount), 151169689Skan M_NULLFSMNT, M_WAITOK | M_ZERO); 15218334Speter 153169689Skan /* 154169689Skan * Save reference to underlying FS 155169689Skan */ 156169689Skan xmp->nullm_vfs = lowerrootvp->v_mount; 157169689Skan 158169689Skan /* 159169689Skan * Save reference. Each mount also holds 160169689Skan * a reference on the root vnode. 161169689Skan */ 16218334Speter error = null_nodeget(mp, lowerrootvp, &vp); 163169689Skan /* 164169689Skan * Make sure the node alias worked 16518334Speter */ 166169689Skan if (error) { 167169689Skan free(xmp, M_NULLFSMNT); 168169689Skan return (error); 16918334Speter } 170169689Skan 17118334Speter /* 172169689Skan * Keep a held reference to the root vnode. 173169689Skan * It is vrele'd in nullfs_unmount. 174169689Skan */ 17518334Speter nullm_rootvp = vp; 176169689Skan nullm_rootvp->v_vflag |= VV_ROOT; 177169689Skan xmp->nullm_rootvp = nullm_rootvp; 178169689Skan 179 /* 180 * Unlock the node (either the lower or the alias) 181 */ 182 VOP_UNLOCK(vp, 0); 183 184 if (NULLVPTOLOWERVP(nullm_rootvp)->v_mount->mnt_flag & MNT_LOCAL) { 185 MNT_ILOCK(mp); 186 mp->mnt_flag |= MNT_LOCAL; 187 MNT_IUNLOCK(mp); 188 } 189 190 xmp->nullm_flags |= NULLM_CACHE; 191 if (vfs_getopt(mp->mnt_optnew, "nocache", NULL, NULL) == 0) 192 xmp->nullm_flags &= ~NULLM_CACHE; 193 194 MNT_ILOCK(mp); 195 if ((xmp->nullm_flags & NULLM_CACHE) != 0) { 196 mp->mnt_kern_flag |= lowerrootvp->v_mount->mnt_kern_flag & 197 (MNTK_SHARED_WRITES | MNTK_LOOKUP_SHARED | 198 MNTK_EXTENDED_SHARED); 199 } 200 mp->mnt_kern_flag |= MNTK_LOOKUP_EXCL_DOTDOT; 201 MNT_IUNLOCK(mp); 202 mp->mnt_data = xmp; 203 vfs_getnewfsid(mp); 204 if ((xmp->nullm_flags & NULLM_CACHE) != 0) { 205 MNT_ILOCK(xmp->nullm_vfs); 206 TAILQ_INSERT_TAIL(&xmp->nullm_vfs->mnt_uppers, mp, 207 mnt_upper_link); 208 MNT_IUNLOCK(xmp->nullm_vfs); 209 } 210 211 vfs_mountedfrom(mp, target); 212 213 NULLFSDEBUG("nullfs_mount: lower %s, alias at %s\n", 214 mp->mnt_stat.f_mntfromname, mp->mnt_stat.f_mntonname); 215 return (0); 216} 217 218/* 219 * Free reference to null layer 220 */ 221static int 222nullfs_unmount(mp, mntflags) 223 struct mount *mp; 224 int mntflags; 225{ 226 struct null_mount *mntdata; 227 struct mount *ump; 228 int error, flags; 229 230 NULLFSDEBUG("nullfs_unmount: mp = %p\n", (void *)mp); 231 232 if (mntflags & MNT_FORCE) 233 flags = FORCECLOSE; 234 else 235 flags = 0; 236 237 /* There is 1 extra root vnode reference (nullm_rootvp). */ 238 error = vflush(mp, 1, flags, curthread); 239 if (error) 240 return (error); 241 242 /* 243 * Finally, throw away the null_mount structure 244 */ 245 mntdata = mp->mnt_data; 246 ump = mntdata->nullm_vfs; 247 if ((mntdata->nullm_flags & NULLM_CACHE) != 0) { 248 MNT_ILOCK(ump); 249 while ((ump->mnt_kern_flag & MNTK_VGONE_UPPER) != 0) { 250 ump->mnt_kern_flag |= MNTK_VGONE_WAITER; 251 msleep(&ump->mnt_uppers, &ump->mnt_mtx, 0, "vgnupw", 0); 252 } 253 TAILQ_REMOVE(&ump->mnt_uppers, mp, mnt_upper_link); 254 MNT_IUNLOCK(ump); 255 } 256 mp->mnt_data = NULL; 257 free(mntdata, M_NULLFSMNT); 258 return (0); 259} 260 261static int 262nullfs_root(mp, flags, vpp) 263 struct mount *mp; 264 int flags; 265 struct vnode **vpp; 266{ 267 struct vnode *vp; 268 269 NULLFSDEBUG("nullfs_root(mp = %p, vp = %p->%p)\n", (void *)mp, 270 (void *)MOUNTTONULLMOUNT(mp)->nullm_rootvp, 271 (void *)NULLVPTOLOWERVP(MOUNTTONULLMOUNT(mp)->nullm_rootvp)); 272 273 /* 274 * Return locked reference to root. 275 */ 276 vp = MOUNTTONULLMOUNT(mp)->nullm_rootvp; 277 VREF(vp); 278 279 ASSERT_VOP_UNLOCKED(vp, "root vnode is locked"); 280 vn_lock(vp, flags | LK_RETRY); 281 *vpp = vp; 282 return 0; 283} 284 285static int 286nullfs_quotactl(mp, cmd, uid, arg) 287 struct mount *mp; 288 int cmd; 289 uid_t uid; 290 void *arg; 291{ 292 return VFS_QUOTACTL(MOUNTTONULLMOUNT(mp)->nullm_vfs, cmd, uid, arg); 293} 294 295static int 296nullfs_statfs(mp, sbp) 297 struct mount *mp; 298 struct statfs *sbp; 299{ 300 int error; 301 struct statfs mstat; 302 303 NULLFSDEBUG("nullfs_statfs(mp = %p, vp = %p->%p)\n", (void *)mp, 304 (void *)MOUNTTONULLMOUNT(mp)->nullm_rootvp, 305 (void *)NULLVPTOLOWERVP(MOUNTTONULLMOUNT(mp)->nullm_rootvp)); 306 307 bzero(&mstat, sizeof(mstat)); 308 309 error = VFS_STATFS(MOUNTTONULLMOUNT(mp)->nullm_vfs, &mstat); 310 if (error) 311 return (error); 312 313 /* now copy across the "interesting" information and fake the rest */ 314 sbp->f_type = mstat.f_type; 315 sbp->f_flags = (sbp->f_flags & (MNT_RDONLY | MNT_NOEXEC | MNT_NOSUID | 316 MNT_UNION | MNT_NOSYMFOLLOW)) | (mstat.f_flags & ~MNT_ROOTFS); 317 sbp->f_bsize = mstat.f_bsize; 318 sbp->f_iosize = mstat.f_iosize; 319 sbp->f_blocks = mstat.f_blocks; 320 sbp->f_bfree = mstat.f_bfree; 321 sbp->f_bavail = mstat.f_bavail; 322 sbp->f_files = mstat.f_files; 323 sbp->f_ffree = mstat.f_ffree; 324 return (0); 325} 326 327static int 328nullfs_sync(mp, waitfor) 329 struct mount *mp; 330 int waitfor; 331{ 332 /* 333 * XXX - Assumes no data cached at null layer. 334 */ 335 return (0); 336} 337 338static int 339nullfs_vget(mp, ino, flags, vpp) 340 struct mount *mp; 341 ino_t ino; 342 int flags; 343 struct vnode **vpp; 344{ 345 int error; 346 347 KASSERT((flags & LK_TYPE_MASK) != 0, 348 ("nullfs_vget: no lock requested")); 349 350 error = VFS_VGET(MOUNTTONULLMOUNT(mp)->nullm_vfs, ino, flags, vpp); 351 if (error != 0) 352 return (error); 353 return (null_nodeget(mp, *vpp, vpp)); 354} 355 356static int 357nullfs_fhtovp(mp, fidp, flags, vpp) 358 struct mount *mp; 359 struct fid *fidp; 360 int flags; 361 struct vnode **vpp; 362{ 363 int error; 364 365 error = VFS_FHTOVP(MOUNTTONULLMOUNT(mp)->nullm_vfs, fidp, flags, 366 vpp); 367 if (error != 0) 368 return (error); 369 return (null_nodeget(mp, *vpp, vpp)); 370} 371 372static int 373nullfs_extattrctl(mp, cmd, filename_vp, namespace, attrname) 374 struct mount *mp; 375 int cmd; 376 struct vnode *filename_vp; 377 int namespace; 378 const char *attrname; 379{ 380 381 return (VFS_EXTATTRCTL(MOUNTTONULLMOUNT(mp)->nullm_vfs, cmd, 382 filename_vp, namespace, attrname)); 383} 384 385static void 386nullfs_reclaim_lowervp(struct mount *mp, struct vnode *lowervp) 387{ 388 struct vnode *vp; 389 390 vp = null_hashget(mp, lowervp); 391 if (vp == NULL) 392 return; 393 VTONULL(vp)->null_flags |= NULLV_NOUNLOCK; 394 vgone(vp); 395 vput(vp); 396} 397 398static void 399nullfs_unlink_lowervp(struct mount *mp, struct vnode *lowervp) 400{ 401 struct vnode *vp; 402 struct null_node *xp; 403 404 vp = null_hashget(mp, lowervp); 405 if (vp == NULL) 406 return; 407 xp = VTONULL(vp); 408 xp->null_flags |= NULLV_DROP | NULLV_NOUNLOCK; 409 vhold(vp); 410 vunref(vp); 411 412 if (vp->v_usecount == 0) { 413 /* 414 * If vunref() dropped the last use reference on the 415 * nullfs vnode, it must be reclaimed, and its lock 416 * was split from the lower vnode lock. Need to do 417 * extra unlock before allowing the final vdrop() to 418 * free the vnode. 419 */ 420 KASSERT((vp->v_iflag & VI_DOOMED) != 0, 421 ("not reclaimed nullfs vnode %p", vp)); 422 VOP_UNLOCK(vp, 0); 423 } else { 424 /* 425 * Otherwise, the nullfs vnode still shares the lock 426 * with the lower vnode, and must not be unlocked. 427 * Also clear the NULLV_NOUNLOCK, the flag is not 428 * relevant for future reclamations. 429 */ 430 ASSERT_VOP_ELOCKED(vp, "unlink_lowervp"); 431 KASSERT((vp->v_iflag & VI_DOOMED) == 0, 432 ("reclaimed nullfs vnode %p", vp)); 433 xp->null_flags &= ~NULLV_NOUNLOCK; 434 } 435 vdrop(vp); 436} 437 438static struct vfsops null_vfsops = { 439 .vfs_extattrctl = nullfs_extattrctl, 440 .vfs_fhtovp = nullfs_fhtovp, 441 .vfs_init = nullfs_init, 442 .vfs_mount = nullfs_mount, 443 .vfs_quotactl = nullfs_quotactl, 444 .vfs_root = nullfs_root, 445 .vfs_statfs = nullfs_statfs, 446 .vfs_sync = nullfs_sync, 447 .vfs_uninit = nullfs_uninit, 448 .vfs_unmount = nullfs_unmount, 449 .vfs_vget = nullfs_vget, 450 .vfs_reclaim_lowervp = nullfs_reclaim_lowervp, 451 .vfs_unlink_lowervp = nullfs_unlink_lowervp, 452}; 453 454VFS_SET(null_vfsops, nullfs, VFCF_LOOPBACK | VFCF_JAIL); 455