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/6.4/sys/fs/nullfs/null_vfsops.c 176599 2008-02-26 18:19:49Z obrien $ 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/kdb.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 54 #include <fs/nullfs/null.h> 55 56 static MALLOC_DEFINE(M_NULLFSMNT, "NULLFS mount", "NULLFS mount structure"); 57 58 static vfs_fhtovp_t nullfs_fhtovp; 59 static vfs_mount_t nullfs_mount; 60 static vfs_quotactl_t nullfs_quotactl; 61 static vfs_root_t nullfs_root; 62 static vfs_sync_t nullfs_sync; 63 static vfs_statfs_t nullfs_statfs; 64 static vfs_unmount_t nullfs_unmount; 65 static vfs_vget_t nullfs_vget; 66 static vfs_vptofh_t nullfs_vptofh; 67 static vfs_extattrctl_t nullfs_extattrctl; 68 69 /* 70 * Mount null layer 71 */ 72 static int 73 nullfs_mount(struct mount *mp, struct thread *td) 74 { 75 int error = 0; 76 struct vnode *lowerrootvp, *vp; 77 struct vnode *nullm_rootvp; 78 struct null_mount *xmp; 79 char *target; 80 int isvnunlocked = 0, len; 81 struct nameidata nd, *ndp = &nd; 82 83 NULLFSDEBUG("nullfs_mount(mp = %p)\n", (void *)mp); 84 85 if (mp->mnt_flag & MNT_ROOTFS) 86 return (EOPNOTSUPP); 87 /* 88 * Update is a no-op 89 */ 90 if (mp->mnt_flag & MNT_UPDATE) { 91 /* 92 * Only support update mounts for NFS export. 93 */ 94 if (vfs_flagopt(mp->mnt_optnew, "export", NULL, 0)) 95 return (0); 96 else 97 return (EOPNOTSUPP); 98 } 99 100 /* 101 * Get argument 102 */ 103 error = vfs_getopt(mp->mnt_optnew, "target", (void **)&target, &len); 104 if (error || target[len - 1] != '\0') 105 return (EINVAL); 106 107 /* 108 * Unlock lower node to avoid deadlock. 109 * (XXX) VOP_ISLOCKED is needed? 110 */ 111 if ((mp->mnt_vnodecovered->v_op == &null_vnodeops) && 112 VOP_ISLOCKED(mp->mnt_vnodecovered, NULL)) { 113 VOP_UNLOCK(mp->mnt_vnodecovered, 0, td); 114 isvnunlocked = 1; 115 } 116 /* 117 * Find lower node 118 */ 119 NDINIT(ndp, LOOKUP, FOLLOW|LOCKLEAF, 120 UIO_SYSSPACE, target, td); 121 error = namei(ndp); 122 /* 123 * Re-lock vnode. 124 */ 125 if (isvnunlocked && !VOP_ISLOCKED(mp->mnt_vnodecovered, NULL)) 126 vn_lock(mp->mnt_vnodecovered, LK_EXCLUSIVE | LK_RETRY, td); 127 128 if (error) 129 return (error); 130 NDFREE(ndp, NDF_ONLY_PNBUF); 131 132 /* 133 * Sanity check on lower vnode 134 */ 135 lowerrootvp = ndp->ni_vp; 136 137 /* 138 * Check multi null mount to avoid `lock against myself' panic. 139 */ 140 if (lowerrootvp == VTONULL(mp->mnt_vnodecovered)->null_lowervp) { 141 NULLFSDEBUG("nullfs_mount: multi null mount?\n"); 142 vput(lowerrootvp); 143 return (EDEADLK); 144 } 145 146 xmp = (struct null_mount *) malloc(sizeof(struct null_mount), 147 M_NULLFSMNT, M_WAITOK); /* XXX */ 148 149 /* 150 * Save reference to underlying FS 151 */ 152 xmp->nullm_vfs = lowerrootvp->v_mount; 153 154 /* 155 * Save reference. Each mount also holds 156 * a reference on the root vnode. 157 */ 158 error = null_nodeget(mp, lowerrootvp, &vp); 159 /* 160 * Make sure the node alias worked 161 */ 162 if (error) { 163 VOP_UNLOCK(vp, 0, td); 164 vrele(lowerrootvp); 165 free(xmp, M_NULLFSMNT); /* XXX */ 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, td); 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 & MNTK_MPSAFE; 189 MNT_IUNLOCK(mp); 190 mp->mnt_data = (qaddr_t) xmp; 191 vfs_getnewfsid(mp); 192 193 vfs_mountedfrom(mp, target); 194 195 NULLFSDEBUG("nullfs_mount: lower %s, alias at %s\n", 196 mp->mnt_stat.f_mntfromname, mp->mnt_stat.f_mntonname); 197 return (0); 198 } 199 200 /* 201 * Free reference to null layer 202 */ 203 static int 204 nullfs_unmount(mp, mntflags, td) 205 struct mount *mp; 206 int mntflags; 207 struct thread *td; 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, td); 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 = 0; 228 free(mntdata, M_NULLFSMNT); 229 return 0; 230 } 231 232 static int 233 nullfs_root(mp, flags, vpp, td) 234 struct mount *mp; 235 int flags; 236 struct vnode **vpp; 237 struct thread *td; 238 { 239 struct vnode *vp; 240 241 NULLFSDEBUG("nullfs_root(mp = %p, vp = %p->%p)\n", (void *)mp, 242 (void *)MOUNTTONULLMOUNT(mp)->nullm_rootvp, 243 (void *)NULLVPTOLOWERVP(MOUNTTONULLMOUNT(mp)->nullm_rootvp)); 244 245 /* 246 * Return locked reference to root. 247 */ 248 vp = MOUNTTONULLMOUNT(mp)->nullm_rootvp; 249 VREF(vp); 250 251 #ifdef NULLFS_DEBUG 252 if (VOP_ISLOCKED(vp, NULL)) { 253 kdb_enter("root vnode is locked.\n"); 254 vrele(vp); 255 return (EDEADLK); 256 } 257 #endif 258 vn_lock(vp, flags | LK_RETRY, td); 259 *vpp = vp; 260 return 0; 261 } 262 263 static int 264 nullfs_quotactl(mp, cmd, uid, arg, td) 265 struct mount *mp; 266 int cmd; 267 uid_t uid; 268 caddr_t arg; 269 struct thread *td; 270 { 271 return VFS_QUOTACTL(MOUNTTONULLMOUNT(mp)->nullm_vfs, cmd, uid, arg, td); 272 } 273 274 static int 275 nullfs_statfs(mp, sbp, td) 276 struct mount *mp; 277 struct statfs *sbp; 278 struct thread *td; 279 { 280 int error; 281 struct statfs mstat; 282 283 NULLFSDEBUG("nullfs_statfs(mp = %p, vp = %p->%p)\n", (void *)mp, 284 (void *)MOUNTTONULLMOUNT(mp)->nullm_rootvp, 285 (void *)NULLVPTOLOWERVP(MOUNTTONULLMOUNT(mp)->nullm_rootvp)); 286 287 bzero(&mstat, sizeof(mstat)); 288 289 error = VFS_STATFS(MOUNTTONULLMOUNT(mp)->nullm_vfs, &mstat, td); 290 if (error) 291 return (error); 292 293 /* now copy across the "interesting" information and fake the rest */ 294 sbp->f_type = mstat.f_type; 295 sbp->f_flags = mstat.f_flags; 296 sbp->f_bsize = mstat.f_bsize; 297 sbp->f_iosize = mstat.f_iosize; 298 sbp->f_blocks = mstat.f_blocks; 299 sbp->f_bfree = mstat.f_bfree; 300 sbp->f_bavail = mstat.f_bavail; 301 sbp->f_files = mstat.f_files; 302 sbp->f_ffree = mstat.f_ffree; 303 return (0); 304 } 305 306 static int 307 nullfs_sync(mp, waitfor, td) 308 struct mount *mp; 309 int waitfor; 310 struct thread *td; 311 { 312 /* 313 * XXX - Assumes no data cached at null layer. 314 */ 315 return (0); 316 } 317 318 static int 319 nullfs_vget(mp, ino, flags, vpp) 320 struct mount *mp; 321 ino_t ino; 322 int flags; 323 struct vnode **vpp; 324 { 325 int error; 326 error = VFS_VGET(MOUNTTONULLMOUNT(mp)->nullm_vfs, ino, flags, vpp); 327 if (error) 328 return (error); 329 330 return (null_nodeget(mp, *vpp, vpp)); 331 } 332 333 static int 334 nullfs_fhtovp(mp, fidp, vpp) 335 struct mount *mp; 336 struct fid *fidp; 337 struct vnode **vpp; 338 { 339 int error; 340 error = VFS_FHTOVP(MOUNTTONULLMOUNT(mp)->nullm_vfs, fidp, vpp); 341 if (error) 342 return (error); 343 344 return (null_nodeget(mp, *vpp, vpp)); 345 } 346 347 static int 348 nullfs_vptofh(vp, fhp) 349 struct vnode *vp; 350 struct fid *fhp; 351 { 352 struct vnode *lvp; 353 354 lvp = NULLVPTOLOWERVP(vp); 355 return VFS_VPTOFH(lvp, fhp); 356 } 357 358 static int 359 nullfs_extattrctl(mp, cmd, filename_vp, namespace, attrname, td) 360 struct mount *mp; 361 int cmd; 362 struct vnode *filename_vp; 363 int namespace; 364 const char *attrname; 365 struct thread *td; 366 { 367 return VFS_EXTATTRCTL(MOUNTTONULLMOUNT(mp)->nullm_vfs, cmd, filename_vp, 368 namespace, attrname, td); 369 } 370 371 372 static struct vfsops null_vfsops = { 373 .vfs_extattrctl = nullfs_extattrctl, 374 .vfs_fhtovp = nullfs_fhtovp, 375 .vfs_init = nullfs_init, 376 .vfs_mount = nullfs_mount, 377 .vfs_quotactl = nullfs_quotactl, 378 .vfs_root = nullfs_root, 379 .vfs_statfs = nullfs_statfs, 380 .vfs_sync = nullfs_sync, 381 .vfs_uninit = nullfs_uninit, 382 .vfs_unmount = nullfs_unmount, 383 .vfs_vget = nullfs_vget, 384 .vfs_vptofh = nullfs_vptofh, 385 }; 386 387 VFS_SET(null_vfsops, nullfs, VFCF_LOOPBACK);
Cache object: 967dca88af5c5b515edb3156ef818340
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