null_vfsops.c revision 166774
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 166774 2007-02-15 22:08:35Z pjd $ 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 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, struct thread *td) 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 deadlock. 108 * (XXX) VOP_ISLOCKED is needed? 109 */ 110 if ((mp->mnt_vnodecovered->v_op == &null_vnodeops) && 111 VOP_ISLOCKED(mp->mnt_vnodecovered, NULL)) { 112 VOP_UNLOCK(mp->mnt_vnodecovered, 0, td); 113 isvnunlocked = 1; 114 } 115 /* 116 * Find lower node 117 */ 118 NDINIT(ndp, LOOKUP, FOLLOW|LOCKLEAF, 119 UIO_SYSSPACE, target, td); 120 error = namei(ndp); 121 /* 122 * Re-lock vnode. 123 */ 124 if (isvnunlocked && !VOP_ISLOCKED(mp->mnt_vnodecovered, NULL)) 125 vn_lock(mp->mnt_vnodecovered, LK_EXCLUSIVE | LK_RETRY, td); 126 127 if (error) 128 return (error); 129 NDFREE(ndp, NDF_ONLY_PNBUF); 130 131 /* 132 * Sanity check on lower vnode 133 */ 134 lowerrootvp = ndp->ni_vp; 135 136 /* 137 * Check multi null mount to avoid `lock against myself' panic. 138 */ 139 if (lowerrootvp == VTONULL(mp->mnt_vnodecovered)->null_lowervp) { 140 NULLFSDEBUG("nullfs_mount: multi null mount?\n"); 141 vput(lowerrootvp); 142 return (EDEADLK); 143 } 144 145 xmp = (struct null_mount *) malloc(sizeof(struct null_mount), 146 M_NULLFSMNT, M_WAITOK); /* XXX */ 147 148 /* 149 * Save reference to underlying FS 150 */ 151 xmp->nullm_vfs = lowerrootvp->v_mount; 152 153 /* 154 * Save reference. Each mount also holds 155 * a reference on the root vnode. 156 */ 157 error = null_nodeget(mp, lowerrootvp, &vp); 158 /* 159 * Make sure the node alias worked 160 */ 161 if (error) { 162 VOP_UNLOCK(vp, 0, td); 163 vrele(lowerrootvp); 164 free(xmp, M_NULLFSMNT); /* XXX */ 165 return (error); 166 } 167 168 /* 169 * Keep a held reference to the root vnode. 170 * It is vrele'd in nullfs_unmount. 171 */ 172 nullm_rootvp = vp; 173 nullm_rootvp->v_vflag |= VV_ROOT; 174 xmp->nullm_rootvp = nullm_rootvp; 175 176 /* 177 * Unlock the node (either the lower or the alias) 178 */ 179 VOP_UNLOCK(vp, 0, td); 180 181 if (NULLVPTOLOWERVP(nullm_rootvp)->v_mount->mnt_flag & MNT_LOCAL) { 182 MNT_ILOCK(mp); 183 mp->mnt_flag |= MNT_LOCAL; 184 MNT_IUNLOCK(mp); 185 } 186 MNT_ILOCK(mp); 187 mp->mnt_kern_flag |= lowerrootvp->v_mount->mnt_kern_flag & MNTK_MPSAFE; 188 MNT_IUNLOCK(mp); 189 mp->mnt_data = (qaddr_t) xmp; 190 vfs_getnewfsid(mp); 191 192 vfs_mountedfrom(mp, target); 193 194 NULLFSDEBUG("nullfs_mount: lower %s, alias at %s\n", 195 mp->mnt_stat.f_mntfromname, mp->mnt_stat.f_mntonname); 196 return (0); 197} 198 199/* 200 * Free reference to null layer 201 */ 202static int 203nullfs_unmount(mp, mntflags, td) 204 struct mount *mp; 205 int mntflags; 206 struct thread *td; 207{ 208 void *mntdata; 209 int error; 210 int flags = 0; 211 212 NULLFSDEBUG("nullfs_unmount: mp = %p\n", (void *)mp); 213 214 if (mntflags & MNT_FORCE) 215 flags |= FORCECLOSE; 216 217 /* There is 1 extra root vnode reference (nullm_rootvp). */ 218 error = vflush(mp, 1, flags, td); 219 if (error) 220 return (error); 221 222 /* 223 * Finally, throw away the null_mount structure 224 */ 225 mntdata = mp->mnt_data; 226 mp->mnt_data = 0; 227 free(mntdata, M_NULLFSMNT); 228 return 0; 229} 230 231static int 232nullfs_root(mp, flags, vpp, td) 233 struct mount *mp; 234 int flags; 235 struct vnode **vpp; 236 struct thread *td; 237{ 238 struct vnode *vp; 239 240 NULLFSDEBUG("nullfs_root(mp = %p, vp = %p->%p)\n", (void *)mp, 241 (void *)MOUNTTONULLMOUNT(mp)->nullm_rootvp, 242 (void *)NULLVPTOLOWERVP(MOUNTTONULLMOUNT(mp)->nullm_rootvp)); 243 244 /* 245 * Return locked reference to root. 246 */ 247 vp = MOUNTTONULLMOUNT(mp)->nullm_rootvp; 248 VREF(vp); 249 250#ifdef NULLFS_DEBUG 251 if (VOP_ISLOCKED(vp, NULL)) { 252 kdb_enter("root vnode is locked.\n"); 253 vrele(vp); 254 return (EDEADLK); 255 } 256#endif 257 vn_lock(vp, flags | LK_RETRY, td); 258 *vpp = vp; 259 return 0; 260} 261 262static int 263nullfs_quotactl(mp, cmd, uid, arg, td) 264 struct mount *mp; 265 int cmd; 266 uid_t uid; 267 void *arg; 268 struct thread *td; 269{ 270 return VFS_QUOTACTL(MOUNTTONULLMOUNT(mp)->nullm_vfs, cmd, uid, arg, td); 271} 272 273static int 274nullfs_statfs(mp, sbp, td) 275 struct mount *mp; 276 struct statfs *sbp; 277 struct thread *td; 278{ 279 int error; 280 struct statfs mstat; 281 282 NULLFSDEBUG("nullfs_statfs(mp = %p, vp = %p->%p)\n", (void *)mp, 283 (void *)MOUNTTONULLMOUNT(mp)->nullm_rootvp, 284 (void *)NULLVPTOLOWERVP(MOUNTTONULLMOUNT(mp)->nullm_rootvp)); 285 286 bzero(&mstat, sizeof(mstat)); 287 288 error = VFS_STATFS(MOUNTTONULLMOUNT(mp)->nullm_vfs, &mstat, td); 289 if (error) 290 return (error); 291 292 /* now copy across the "interesting" information and fake the rest */ 293 sbp->f_type = mstat.f_type; 294 sbp->f_flags = mstat.f_flags; 295 sbp->f_bsize = mstat.f_bsize; 296 sbp->f_iosize = mstat.f_iosize; 297 sbp->f_blocks = mstat.f_blocks; 298 sbp->f_bfree = mstat.f_bfree; 299 sbp->f_bavail = mstat.f_bavail; 300 sbp->f_files = mstat.f_files; 301 sbp->f_ffree = mstat.f_ffree; 302 return (0); 303} 304 305static int 306nullfs_sync(mp, waitfor, td) 307 struct mount *mp; 308 int waitfor; 309 struct thread *td; 310{ 311 /* 312 * XXX - Assumes no data cached at null layer. 313 */ 314 return (0); 315} 316 317static int 318nullfs_vget(mp, ino, flags, vpp) 319 struct mount *mp; 320 ino_t ino; 321 int flags; 322 struct vnode **vpp; 323{ 324 int error; 325 error = VFS_VGET(MOUNTTONULLMOUNT(mp)->nullm_vfs, ino, flags, vpp); 326 if (error) 327 return (error); 328 329 return (null_nodeget(mp, *vpp, vpp)); 330} 331 332static int 333nullfs_fhtovp(mp, fidp, vpp) 334 struct mount *mp; 335 struct fid *fidp; 336 struct vnode **vpp; 337{ 338 int error; 339 error = VFS_FHTOVP(MOUNTTONULLMOUNT(mp)->nullm_vfs, fidp, vpp); 340 if (error) 341 return (error); 342 343 return (null_nodeget(mp, *vpp, vpp)); 344} 345 346static int 347nullfs_extattrctl(mp, cmd, filename_vp, namespace, attrname, td) 348 struct mount *mp; 349 int cmd; 350 struct vnode *filename_vp; 351 int namespace; 352 const char *attrname; 353 struct thread *td; 354{ 355 return VFS_EXTATTRCTL(MOUNTTONULLMOUNT(mp)->nullm_vfs, cmd, filename_vp, 356 namespace, attrname, td); 357} 358 359 360static struct vfsops null_vfsops = { 361 .vfs_extattrctl = nullfs_extattrctl, 362 .vfs_fhtovp = nullfs_fhtovp, 363 .vfs_init = nullfs_init, 364 .vfs_mount = nullfs_mount, 365 .vfs_quotactl = nullfs_quotactl, 366 .vfs_root = nullfs_root, 367 .vfs_statfs = nullfs_statfs, 368 .vfs_sync = nullfs_sync, 369 .vfs_uninit = nullfs_uninit, 370 .vfs_unmount = nullfs_unmount, 371 .vfs_vget = nullfs_vget, 372}; 373 374VFS_SET(null_vfsops, nullfs, VFCF_LOOPBACK); 375