null_vfsops.c revision 226686
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 226686 2011-10-24 13:48:13Z 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 54#include <fs/nullfs/null.h> 55 56static MALLOC_DEFINE(M_NULLFSMNT, "nullfs_mount", "NULLFS mount structure"); 57 58static vfs_fhtovp_t nullfs_fhtovp; 59static vfs_mount_t nullfs_mount; 60static vfs_quotactl_t nullfs_quotactl; 61static vfs_root_t nullfs_root; 62static vfs_sync_t nullfs_sync; 63static vfs_statfs_t nullfs_statfs; 64static vfs_unmount_t nullfs_unmount; 65static vfs_vget_t nullfs_vget; 66static vfs_extattrctl_t nullfs_extattrctl; 67 68/* 69 * Mount null layer 70 */ 71static int 72nullfs_mount(struct mount *mp) 73{ 74 int error = 0; 75 struct vnode *lowerrootvp, *vp; 76 struct vnode *nullm_rootvp; 77 struct null_mount *xmp; 78 char *target; 79 int isvnunlocked = 0, len; 80 struct nameidata nd, *ndp = &nd; 81 82 NULLFSDEBUG("nullfs_mount(mp = %p)\n", (void *)mp); 83 84 if (mp->mnt_flag & MNT_ROOTFS) 85 return (EOPNOTSUPP); 86 /* 87 * Update is a no-op 88 */ 89 if (mp->mnt_flag & MNT_UPDATE) { 90 /* 91 * Only support update mounts for NFS export. 92 */ 93 if (vfs_flagopt(mp->mnt_optnew, "export", NULL, 0)) 94 return (0); 95 else 96 return (EOPNOTSUPP); 97 } 98 99 /* 100 * Get argument 101 */ 102 error = vfs_getopt(mp->mnt_optnew, "target", (void **)&target, &len); 103 if (error || target[len - 1] != '\0') 104 return (EINVAL); 105 106 /* 107 * Unlock lower node to avoid possible deadlock. 108 */ 109 if ((mp->mnt_vnodecovered->v_op == &null_vnodeops) && 110 VOP_ISLOCKED(mp->mnt_vnodecovered) == LK_EXCLUSIVE) { 111 VOP_UNLOCK(mp->mnt_vnodecovered, 0); 112 isvnunlocked = 1; 113 } 114 /* 115 * Find lower node 116 */ 117 NDINIT(ndp, LOOKUP, FOLLOW|LOCKLEAF, UIO_SYSSPACE, target, curthread); 118 error = namei(ndp); 119 /* 120 * Re-lock vnode. 121 */ 122 if (isvnunlocked) 123 vn_lock(mp->mnt_vnodecovered, LK_EXCLUSIVE | LK_RETRY); 124 125 if (error) 126 return (error); 127 NDFREE(ndp, NDF_ONLY_PNBUF); 128 129 /* 130 * Sanity check on lower vnode 131 */ 132 lowerrootvp = ndp->ni_vp; 133 134 /* 135 * Check multi null mount to avoid `lock against myself' panic. 136 */ 137 if (lowerrootvp == VTONULL(mp->mnt_vnodecovered)->null_lowervp) { 138 NULLFSDEBUG("nullfs_mount: multi null mount?\n"); 139 vput(lowerrootvp); 140 return (EDEADLK); 141 } 142 143 xmp = (struct null_mount *) malloc(sizeof(struct null_mount), 144 M_NULLFSMNT, M_WAITOK); /* XXX */ 145 146 /* 147 * Save reference to underlying FS 148 */ 149 xmp->nullm_vfs = lowerrootvp->v_mount; 150 151 /* 152 * Save reference. Each mount also holds 153 * a reference on the root vnode. 154 */ 155 error = null_nodeget(mp, lowerrootvp, &vp); 156 /* 157 * Make sure the node alias worked 158 */ 159 if (error) { 160 VOP_UNLOCK(vp, 0); 161 vrele(lowerrootvp); 162 free(xmp, M_NULLFSMNT); /* XXX */ 163 return (error); 164 } 165 166 /* 167 * Keep a held reference to the root vnode. 168 * It is vrele'd in nullfs_unmount. 169 */ 170 nullm_rootvp = vp; 171 nullm_rootvp->v_vflag |= VV_ROOT; 172 xmp->nullm_rootvp = nullm_rootvp; 173 174 /* 175 * Unlock the node (either the lower or the alias) 176 */ 177 VOP_UNLOCK(vp, 0); 178 179 if (NULLVPTOLOWERVP(nullm_rootvp)->v_mount->mnt_flag & MNT_LOCAL) { 180 MNT_ILOCK(mp); 181 mp->mnt_flag |= MNT_LOCAL; 182 MNT_IUNLOCK(mp); 183 } 184 MNT_ILOCK(mp); 185 mp->mnt_kern_flag |= lowerrootvp->v_mount->mnt_kern_flag & MNTK_MPSAFE; 186 MNT_IUNLOCK(mp); 187 mp->mnt_data = xmp; 188 vfs_getnewfsid(mp); 189 190 vfs_mountedfrom(mp, target); 191 192 NULLFSDEBUG("nullfs_mount: lower %s, alias at %s\n", 193 mp->mnt_stat.f_mntfromname, mp->mnt_stat.f_mntonname); 194 return (0); 195} 196 197/* 198 * Free reference to null layer 199 */ 200static int 201nullfs_unmount(mp, mntflags) 202 struct mount *mp; 203 int mntflags; 204{ 205 void *mntdata; 206 int error; 207 int flags = 0; 208 209 NULLFSDEBUG("nullfs_unmount: mp = %p\n", (void *)mp); 210 211 if (mntflags & MNT_FORCE) 212 flags |= FORCECLOSE; 213 214 /* There is 1 extra root vnode reference (nullm_rootvp). */ 215 error = vflush(mp, 1, flags, curthread); 216 if (error) 217 return (error); 218 219 /* 220 * Finally, throw away the null_mount structure 221 */ 222 mntdata = mp->mnt_data; 223 mp->mnt_data = 0; 224 free(mntdata, M_NULLFSMNT); 225 return 0; 226} 227 228static int 229nullfs_root(mp, flags, vpp) 230 struct mount *mp; 231 int flags; 232 struct vnode **vpp; 233{ 234 struct vnode *vp; 235 236 NULLFSDEBUG("nullfs_root(mp = %p, vp = %p->%p)\n", (void *)mp, 237 (void *)MOUNTTONULLMOUNT(mp)->nullm_rootvp, 238 (void *)NULLVPTOLOWERVP(MOUNTTONULLMOUNT(mp)->nullm_rootvp)); 239 240 /* 241 * Return locked reference to root. 242 */ 243 vp = MOUNTTONULLMOUNT(mp)->nullm_rootvp; 244 VREF(vp); 245 246#ifdef NULLFS_DEBUG 247 if (VOP_ISLOCKED(vp)) 248 panic("root vnode is locked.\n"); 249#endif 250 vn_lock(vp, flags | LK_RETRY); 251 *vpp = vp; 252 return 0; 253} 254 255static int 256nullfs_quotactl(mp, cmd, uid, arg) 257 struct mount *mp; 258 int cmd; 259 uid_t uid; 260 void *arg; 261{ 262 return VFS_QUOTACTL(MOUNTTONULLMOUNT(mp)->nullm_vfs, cmd, uid, arg); 263} 264 265static int 266nullfs_statfs(mp, sbp) 267 struct mount *mp; 268 struct statfs *sbp; 269{ 270 int error; 271 struct statfs mstat; 272 273 NULLFSDEBUG("nullfs_statfs(mp = %p, vp = %p->%p)\n", (void *)mp, 274 (void *)MOUNTTONULLMOUNT(mp)->nullm_rootvp, 275 (void *)NULLVPTOLOWERVP(MOUNTTONULLMOUNT(mp)->nullm_rootvp)); 276 277 bzero(&mstat, sizeof(mstat)); 278 279 error = VFS_STATFS(MOUNTTONULLMOUNT(mp)->nullm_vfs, &mstat); 280 if (error) 281 return (error); 282 283 /* now copy across the "interesting" information and fake the rest */ 284 sbp->f_type = mstat.f_type; 285 sbp->f_flags = mstat.f_flags; 286 sbp->f_bsize = mstat.f_bsize; 287 sbp->f_iosize = mstat.f_iosize; 288 sbp->f_blocks = mstat.f_blocks; 289 sbp->f_bfree = mstat.f_bfree; 290 sbp->f_bavail = mstat.f_bavail; 291 sbp->f_files = mstat.f_files; 292 sbp->f_ffree = mstat.f_ffree; 293 return (0); 294} 295 296static int 297nullfs_sync(mp, waitfor) 298 struct mount *mp; 299 int waitfor; 300{ 301 /* 302 * XXX - Assumes no data cached at null layer. 303 */ 304 return (0); 305} 306 307static int 308nullfs_vget(mp, ino, flags, vpp) 309 struct mount *mp; 310 ino_t ino; 311 int flags; 312 struct vnode **vpp; 313{ 314 int error; 315 error = VFS_VGET(MOUNTTONULLMOUNT(mp)->nullm_vfs, ino, flags, vpp); 316 if (error) 317 return (error); 318 319 return (null_nodeget(mp, *vpp, vpp)); 320} 321 322static int 323nullfs_fhtovp(mp, fidp, flags, vpp) 324 struct mount *mp; 325 struct fid *fidp; 326 int flags; 327 struct vnode **vpp; 328{ 329 int error; 330 error = VFS_FHTOVP(MOUNTTONULLMOUNT(mp)->nullm_vfs, fidp, LK_EXCLUSIVE, 331 vpp); 332 if (error) 333 return (error); 334 335 return (null_nodeget(mp, *vpp, vpp)); 336} 337 338static int 339nullfs_extattrctl(mp, cmd, filename_vp, namespace, attrname) 340 struct mount *mp; 341 int cmd; 342 struct vnode *filename_vp; 343 int namespace; 344 const char *attrname; 345{ 346 return VFS_EXTATTRCTL(MOUNTTONULLMOUNT(mp)->nullm_vfs, cmd, filename_vp, 347 namespace, attrname); 348} 349 350 351static struct vfsops null_vfsops = { 352 .vfs_extattrctl = nullfs_extattrctl, 353 .vfs_fhtovp = nullfs_fhtovp, 354 .vfs_init = nullfs_init, 355 .vfs_mount = nullfs_mount, 356 .vfs_quotactl = nullfs_quotactl, 357 .vfs_root = nullfs_root, 358 .vfs_statfs = nullfs_statfs, 359 .vfs_sync = nullfs_sync, 360 .vfs_uninit = nullfs_uninit, 361 .vfs_unmount = nullfs_unmount, 362 .vfs_vget = nullfs_vget, 363}; 364 365VFS_SET(null_vfsops, nullfs, VFCF_LOOPBACK); 366