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 * 3. All advertising materials mentioning features or use of this software 17 * must display the following acknowledgement: 18 * This product includes software developed by the University of 19 * California, Berkeley and its contributors. 20 * 4. Neither the name of the University nor the names of its contributors 21 * may be used to endorse or promote products derived from this software 22 * without specific prior written permission. 23 * 24 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 25 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 26 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 27 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 28 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 29 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 30 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 31 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 32 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 33 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 34 * SUCH DAMAGE. 35 * 36 * @(#)null_vfsops.c 8.2 (Berkeley) 1/21/94 37 * 38 * @(#)lofs_vfsops.c 1.2 (Berkeley) 6/18/92 39 * $FreeBSD: src/sys/miscfs/nullfs/null_vfsops.c,v 1.35.2.3 2001/07/26 20:37:11 iedowse Exp $ 40 * $DragonFly: src/sys/vfs/nullfs/null_vfsops.c,v 1.18 2005/09/17 07:43:12 dillon Exp $ 41 */ 42 43 /* 44 * Null Layer 45 * (See null_vnops.c for a description of what this does.) 46 */ 47 48 #include <sys/param.h> 49 #include <sys/systm.h> 50 #include <sys/kernel.h> 51 #include <sys/proc.h> 52 #include <sys/malloc.h> 53 #include <sys/vnode.h> 54 #include <sys/mount.h> 55 #include <sys/nlookup.h> 56 #include "null.h" 57 58 extern struct vnodeopv_entry_desc null_vnodeop_entries[]; 59 60 static MALLOC_DEFINE(M_NULLFSMNT, "NULLFS mount", "NULLFS mount structure"); 61 62 static int nullfs_fhtovp(struct mount *mp, struct fid *fidp, 63 struct vnode **vpp); 64 static int nullfs_checkexp(struct mount *mp, struct sockaddr *nam, 65 int *extflagsp, struct ucred **credanonp); 66 static int nullfs_mount(struct mount *mp, char *path, caddr_t data, 67 struct thread *td); 68 static int nullfs_quotactl(struct mount *mp, int cmd, uid_t uid, 69 caddr_t arg, struct thread *td); 70 static int nullfs_root(struct mount *mp, struct vnode **vpp); 71 static int nullfs_statfs(struct mount *mp, struct statfs *sbp, 72 struct thread *td); 73 static int nullfs_unmount(struct mount *mp, int mntflags, struct thread *td); 74 static int nullfs_vget(struct mount *mp, ino_t ino, struct vnode **vpp); 75 static int nullfs_vptofh(struct vnode *vp, struct fid *fhp); 76 static int nullfs_extattrctl(struct mount *mp, int cmd, 77 const char *attrname, caddr_t arg, struct thread *td); 78 79 /* 80 * Mount null layer 81 */ 82 static int 83 nullfs_mount(struct mount *mp, char *path, caddr_t data, struct thread *td) 84 { 85 int error = 0; 86 struct null_args args; 87 struct vnode *lowerrootvp, *vp; 88 struct vnode *nullm_rootvp; 89 struct null_mount *xmp; 90 u_int size; 91 int isvnunlocked = 0; 92 struct nlookupdata nd; 93 94 NULLFSDEBUG("nullfs_mount(mp = %p)\n", (void *)mp); 95 96 /* 97 * Update is a no-op 98 */ 99 if (mp->mnt_flag & MNT_UPDATE) { 100 return (EOPNOTSUPP); 101 } 102 103 /* 104 * Get argument 105 */ 106 error = copyin(data, (caddr_t)&args, sizeof(struct null_args)); 107 if (error) 108 return (error); 109 110 /* 111 * Unlock lower node to avoid deadlock. 112 * (XXX) VOP_ISLOCKED is needed? 113 */ 114 if ((mp->mnt_vnodecovered->v_tag == VT_NULL) && 115 VOP_ISLOCKED(mp->mnt_vnodecovered, NULL)) { 116 VOP_UNLOCK(mp->mnt_vnodecovered, 0, td); 117 isvnunlocked = 1; 118 } 119 /* 120 * Find lower node 121 */ 122 lowerrootvp = NULL; 123 error = nlookup_init(&nd, args.target, UIO_USERSPACE, NLC_FOLLOW); 124 if (error == 0) 125 error = nlookup(&nd); 126 if (error == 0) { 127 error = cache_vget(nd.nl_ncp, nd.nl_cred, LK_EXCLUSIVE, 128 &lowerrootvp); 129 } 130 nlookup_done(&nd); 131 132 /* 133 * Re-lock vnode. 134 */ 135 if (isvnunlocked && !VOP_ISLOCKED(mp->mnt_vnodecovered, NULL)) 136 vn_lock(mp->mnt_vnodecovered, LK_EXCLUSIVE | LK_RETRY, td); 137 if (error) 138 return (error); 139 140 /* 141 * Sanity check on lower vnode 142 * 143 * Check multi null mount to avoid `lock against myself' panic. 144 */ 145 if (lowerrootvp == VTONULL(mp->mnt_vnodecovered)->null_lowervp) { 146 NULLFSDEBUG("nullfs_mount: multi null mount?\n"); 147 vput(lowerrootvp); 148 return (EDEADLK); 149 } 150 151 xmp = (struct null_mount *) malloc(sizeof(struct null_mount), 152 M_NULLFSMNT, M_WAITOK); /* XXX */ 153 154 /* 155 * Save reference to underlying FS 156 */ 157 xmp->nullm_vfs = lowerrootvp->v_mount; 158 159 vfs_add_vnodeops(mp, &mp->mnt_vn_norm_ops, 160 null_vnodeop_entries, 0); 161 162 /* 163 * Save reference. Each mount also holds 164 * a reference on the root vnode. 165 */ 166 error = null_node_create(mp, lowerrootvp, &vp); 167 /* 168 * Unlock the node (either the lower or the alias) 169 */ 170 VOP_UNLOCK(vp, 0, td); 171 /* 172 * Make sure the node alias worked 173 */ 174 if (error) { 175 vrele(lowerrootvp); 176 free(xmp, M_NULLFSMNT); /* XXX */ 177 return (error); 178 } 179 180 /* 181 * Keep a held reference to the root vnode. 182 * It is vrele'd in nullfs_unmount. 183 */ 184 nullm_rootvp = vp; 185 nullm_rootvp->v_flag |= VROOT; 186 xmp->nullm_rootvp = nullm_rootvp; 187 if (NULLVPTOLOWERVP(nullm_rootvp)->v_mount->mnt_flag & MNT_LOCAL) 188 mp->mnt_flag |= MNT_LOCAL; 189 mp->mnt_data = (qaddr_t) xmp; 190 vfs_getnewfsid(mp); 191 192 (void) copyinstr(args.target, mp->mnt_stat.f_mntfromname, MNAMELEN - 1, 193 &size); 194 bzero(mp->mnt_stat.f_mntfromname + size, MNAMELEN - size); 195 (void)nullfs_statfs(mp, &mp->mnt_stat, td); 196 NULLFSDEBUG("nullfs_mount: lower %s, alias at %s\n", 197 mp->mnt_stat.f_mntfromname, mp->mnt_stat.f_mntfromname); 198 return (0); 199 } 200 201 /* 202 * Free reference to null layer 203 */ 204 static int 205 nullfs_unmount(struct mount *mp, int mntflags, struct thread *td) 206 { 207 void *mntdata; 208 int error; 209 int flags = 0; 210 211 NULLFSDEBUG("nullfs_unmount: mp = %p\n", (void *)mp); 212 213 if (mntflags & MNT_FORCE) 214 flags |= FORCECLOSE; 215 216 /* There is 1 extra root vnode reference (nullm_rootvp). */ 217 error = vflush(mp, 1, flags); 218 if (error) 219 return (error); 220 221 /* 222 * Finally, throw away the null_mount structure 223 */ 224 mntdata = mp->mnt_data; 225 mp->mnt_data = 0; 226 free(mntdata, M_NULLFSMNT); 227 return 0; 228 } 229 230 static int 231 nullfs_root(struct mount *mp, struct vnode **vpp) 232 { 233 struct thread *td = curthread; /* XXX */ 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, NULL)) { 248 Debugger("root vnode is locked.\n"); 249 vrele(vp); 250 return (EDEADLK); 251 } 252 #endif 253 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, td); 254 *vpp = vp; 255 return 0; 256 } 257 258 static int 259 nullfs_quotactl(struct mount *mp, int cmd, uid_t uid, caddr_t arg, 260 struct thread *td) 261 { 262 return VFS_QUOTACTL(MOUNTTONULLMOUNT(mp)->nullm_vfs, cmd, uid, arg, td); 263 } 264 265 static int 266 nullfs_statfs(struct mount *mp, struct statfs *sbp, struct thread *td) 267 { 268 int error; 269 struct statfs mstat; 270 271 NULLFSDEBUG("nullfs_statfs(mp = %p, vp = %p->%p)\n", (void *)mp, 272 (void *)MOUNTTONULLMOUNT(mp)->nullm_rootvp, 273 (void *)NULLVPTOLOWERVP(MOUNTTONULLMOUNT(mp)->nullm_rootvp)); 274 275 bzero(&mstat, sizeof(mstat)); 276 277 error = VFS_STATFS(MOUNTTONULLMOUNT(mp)->nullm_vfs, &mstat, td); 278 if (error) 279 return (error); 280 281 /* now copy across the "interesting" information and fake the rest */ 282 sbp->f_type = mstat.f_type; 283 sbp->f_flags = mstat.f_flags; 284 sbp->f_bsize = mstat.f_bsize; 285 sbp->f_iosize = mstat.f_iosize; 286 sbp->f_blocks = mstat.f_blocks; 287 sbp->f_bfree = mstat.f_bfree; 288 sbp->f_bavail = mstat.f_bavail; 289 sbp->f_files = mstat.f_files; 290 sbp->f_ffree = mstat.f_ffree; 291 if (sbp != &mp->mnt_stat) { 292 bcopy(&mp->mnt_stat.f_fsid, &sbp->f_fsid, sizeof(sbp->f_fsid)); 293 bcopy(mp->mnt_stat.f_mntfromname, sbp->f_mntfromname, MNAMELEN); 294 } 295 return (0); 296 } 297 298 static int 299 nullfs_vget(struct mount *mp, ino_t ino, struct vnode **vpp) 300 { 301 302 return VFS_VGET(MOUNTTONULLMOUNT(mp)->nullm_vfs, ino, vpp); 303 } 304 305 static int 306 nullfs_fhtovp(struct mount *mp, struct fid *fidp, struct vnode **vpp) 307 { 308 309 return VFS_FHTOVP(MOUNTTONULLMOUNT(mp)->nullm_vfs, fidp, vpp); 310 } 311 312 static int 313 nullfs_checkexp(struct mount *mp, struct sockaddr *nam, int *extflagsp, 314 struct ucred **credanonp) 315 { 316 317 return VFS_CHECKEXP(MOUNTTONULLMOUNT(mp)->nullm_vfs, nam, 318 extflagsp, credanonp); 319 } 320 321 static int 322 nullfs_vptofh(struct vnode *vp, struct fid *fhp) 323 { 324 return VFS_VPTOFH(NULLVPTOLOWERVP(vp), fhp); 325 } 326 327 static int 328 nullfs_extattrctl(struct mount *mp, int cmd, const char *attrname, caddr_t arg, 329 struct thread *td) 330 { 331 return VFS_EXTATTRCTL(MOUNTTONULLMOUNT(mp)->nullm_vfs, cmd, attrname, 332 arg, td); 333 } 334 335 336 static struct vfsops null_vfsops = { 337 .vfs_mount = nullfs_mount, 338 .vfs_unmount = nullfs_unmount, 339 .vfs_root = nullfs_root, 340 .vfs_quotactl = nullfs_quotactl, 341 .vfs_statfs = nullfs_statfs, 342 .vfs_sync = vfs_stdsync, 343 .vfs_vget = nullfs_vget, 344 .vfs_fhtovp = nullfs_fhtovp, 345 .vfs_checkexp = nullfs_checkexp, 346 .vfs_vptofh = nullfs_vptofh, 347 .vfs_init = nullfs_init, 348 .vfs_uninit = nullfs_uninit, 349 .vfs_extattrctl = nullfs_extattrctl 350 }; 351 352 VFS_SET(null_vfsops, null, VFCF_LOOPBACK); 353