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: releng/10.0/sys/fs/nullfs/null_vfsops.c 250852 2013-05-21 11:31:56Z 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 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 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 if (mp->mnt_flag & MNT_ROOTFS) 89 return (EOPNOTSUPP); 90 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 /* 126 * Re-lock vnode. 127 * XXXKIB This is deadlock-prone as well. 128 */ 129 if (isvnunlocked) 130 vn_lock(mp->mnt_vnodecovered, LK_EXCLUSIVE | LK_RETRY); 131 132 if (error) 133 return (error); 134 NDFREE(ndp, NDF_ONLY_PNBUF); 135 136 /* 137 * Sanity check on lower vnode 138 */ 139 lowerrootvp = ndp->ni_vp; 140 141 /* 142 * Check multi null mount to avoid `lock against myself' panic. 143 */ 144 if (lowerrootvp == VTONULL(mp->mnt_vnodecovered)->null_lowervp) { 145 NULLFSDEBUG("nullfs_mount: multi null mount?\n"); 146 vput(lowerrootvp); 147 return (EDEADLK); 148 } 149 150 xmp = (struct null_mount *) malloc(sizeof(struct null_mount), 151 M_NULLFSMNT, M_WAITOK | M_ZERO); 152 153 /* 154 * Save reference to underlying FS 155 */ 156 xmp->nullm_vfs = lowerrootvp->v_mount; 157 158 /* 159 * Save reference. Each mount also holds 160 * a reference on the root vnode. 161 */ 162 error = null_nodeget(mp, lowerrootvp, &vp); 163 /* 164 * Make sure the node alias worked 165 */ 166 if (error) { 167 free(xmp, M_NULLFSMNT); 168 return (error); 169 } 170 171 /* 172 * Keep a held reference to the root vnode. 173 * It is vrele'd in nullfs_unmount. 174 */ 175 nullm_rootvp = vp; 176 nullm_rootvp->v_vflag |= VV_ROOT; 177 xmp->nullm_rootvp = nullm_rootvp; 178 179 /* 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 */ 221 static int 222 nullfs_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 } 260 261 static int 262 nullfs_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 } 284 285 static int 286 nullfs_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 } 294 295 static int 296 nullfs_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 } 326 327 static int 328 nullfs_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 } 337 338 static int 339 nullfs_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 } 355 356 static int 357 nullfs_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 } 371 372 static int 373 nullfs_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 } 384 385 static void 386 nullfs_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 } 397 398 static void 399 nullfs_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 } 437 438 static 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 }; 453 454 VFS_SET(null_vfsops, nullfs, VFCF_LOOPBACK | VFCF_JAIL);
Cache object: 9396b81cb4d1d79129344ec35f5f8dbe
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