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 1.31 2008/09/17 21:44:25 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 <sys/mountctl.h> 57 #include "null.h" 58 59 extern struct vop_ops null_vnode_vops; 60 61 static MALLOC_DEFINE(M_NULLFSMNT, "NULLFS mount", "NULLFS mount structure"); 62 63 static int nullfs_root(struct mount *mp, struct vnode **vpp); 64 static int nullfs_statfs(struct mount *mp, struct statfs *sbp, 65 struct ucred *cred); 66 67 /* 68 * Mount null layer 69 */ 70 static int 71 nullfs_mount(struct mount *mp, char *path, caddr_t data, struct ucred *cred) 72 { 73 int error = 0; 74 struct null_args args; 75 struct vnode *rootvp; 76 struct null_mount *xmp; 77 u_int size; 78 struct nlookupdata nd; 79 fhandle_t fh; 80 81 NULLFSDEBUG("nullfs_mount(mp = %p)\n", (void *)mp); 82 83 /* 84 * Update is a no-op 85 */ 86 if (mp->mnt_flag & MNT_UPDATE) { 87 return (EOPNOTSUPP); 88 } 89 90 /* 91 * Get argument 92 */ 93 error = copyin(data, (caddr_t)&args, sizeof(struct null_args)); 94 if (error) 95 return (error); 96 97 /* 98 * Find lower node 99 */ 100 rootvp = NULL; 101 error = nlookup_init(&nd, args.target, UIO_USERSPACE, NLC_FOLLOW); 102 if (error) 103 goto fail1; 104 error = nlookup(&nd); 105 if (error) 106 goto fail2; 107 error = cache_vget(&nd.nl_nch, nd.nl_cred, LK_EXCLUSIVE, &rootvp); 108 if (error) 109 goto fail2; 110 111 xmp = (struct null_mount *) kmalloc(sizeof(struct null_mount), 112 M_NULLFSMNT, M_WAITOK | M_ZERO); 113 114 /* 115 * Save reference to underlying FS 116 * 117 * As lite stacking enters the scene, the old way of doing this 118 * -- via the vnode -- is not good enough anymore. Use the 119 * underlying filesystem's namecache handle as our mount point 120 * root, adjusting the mount to point to us. 121 * 122 * NCF_ISMOUNTPT is normally set on the mount point, but we also 123 * want to set it on the base directory being mounted to prevent 124 * that directory from being destroyed out from under the nullfs 125 * mount. 126 * 127 * The forwarding mount pointer (xmp->nullm_vfs) must be set to 128 * the actual target filesystem. If the target filesystem was 129 * resolved via a nullfs mount nd.nl_nch.mount will be pointing 130 * to the nullfs mount structure instead of the target filesystem, 131 * which would otherwise cause the mount VOPS and VFSOPS to recurse 132 * endlessly. If we are mounting via a nullfs mount we inherit 133 * its read-only state, if set. 134 */ 135 xmp->nullm_vfs = nd.nl_nch.mount; 136 if (xmp->nullm_vfs != rootvp->v_mount) { 137 if (xmp->nullm_vfs->mnt_flag & MNT_RDONLY) 138 mp->mnt_flag |= MNT_RDONLY; 139 xmp->nullm_vfs = rootvp->v_mount; 140 } 141 142 /* 143 * ncmountpt is the parent glue. When mounting a nullfs via a nullfs 144 * we retain the parent nullfs to create a unique chain tuple. 145 */ 146 mp->mnt_ncmountpt = nd.nl_nch; 147 cache_changemount(&mp->mnt_ncmountpt, mp); 148 mp->mnt_ncmountpt.ncp->nc_flag |= NCF_ISMOUNTPT; 149 cache_unlock(&mp->mnt_ncmountpt); 150 cache_zero(&nd.nl_nch); 151 nlookup_done(&nd); 152 153 vfs_add_vnodeops(mp, &null_vnode_vops, &mp->mnt_vn_norm_ops); 154 155 vn_unlock(rootvp); /* leave reference intact */ 156 157 /* 158 * Keep a held reference to the root vnode. 159 * It is vrele'd in nullfs_unmount. 160 */ 161 xmp->nullm_rootvp = rootvp; 162 /* 163 * XXX What's the proper safety condition for querying 164 * the underlying mount? Is this flag tuning necessary 165 * at all? 166 */ 167 if (xmp->nullm_vfs->mnt_flag & MNT_LOCAL) 168 mp->mnt_flag |= MNT_LOCAL; 169 mp->mnt_data = (qaddr_t) xmp; 170 171 /* 172 * Try to create a unique but non-random fsid for the nullfs to 173 * allow it to be exported via NFS. 174 */ 175 bzero(&fh, sizeof(fh)); 176 fh.fh_fsid = rootvp->v_mount->mnt_stat.f_fsid; 177 if (VFS_VPTOFH(rootvp, &fh.fh_fid) == 0) { 178 fh.fh_fsid.val[1] ^= crc32(&fh.fh_fid, sizeof(fh.fh_fid)); 179 vfs_setfsid(mp, &fh.fh_fsid); 180 } else { 181 vfs_getnewfsid(mp); 182 } 183 184 (void) copyinstr(args.target, mp->mnt_stat.f_mntfromname, MNAMELEN - 1, 185 &size); 186 bzero(mp->mnt_stat.f_mntfromname + size, MNAMELEN - size); 187 (void)nullfs_statfs(mp, &mp->mnt_stat, cred); 188 NULLFSDEBUG("nullfs_mount: lower %s, alias at %s\n", 189 mp->mnt_stat.f_mntfromname, mp->mnt_stat.f_mntfromname); 190 191 /* 192 * So unmount won't complain about namecache refs still existing 193 */ 194 mp->mnt_kern_flag |= MNTK_NCALIASED; 195 return (0); 196 fail2: 197 nlookup_done(&nd); 198 fail1: 199 return (error); 200 } 201 202 /* 203 * Free reference to null layer 204 */ 205 static int 206 nullfs_unmount(struct mount *mp, int mntflags) 207 { 208 struct null_mount *xmp; 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 /* 217 * Finally, throw away the null_mount structure 218 */ 219 xmp = (void *)mp->mnt_data; 220 mp->mnt_data = 0; 221 if (xmp->nullm_rootvp) { 222 vrele(xmp->nullm_rootvp); 223 xmp->nullm_rootvp = NULL; 224 } 225 kfree(xmp, M_NULLFSMNT); 226 return 0; 227 } 228 229 static int 230 nullfs_root(struct mount *mp, struct vnode **vpp) 231 { 232 struct vnode *vp; 233 int error; 234 235 NULLFSDEBUG("nullfs_root(mp = %p, vp = %p)\n", (void *)mp, 236 (void *)MOUNTTONULLMOUNT(mp)->nullm_rootvp); 237 238 /* 239 * Return locked reference to root. 240 */ 241 vp = MOUNTTONULLMOUNT(mp)->nullm_rootvp; 242 error = vget(vp, LK_EXCLUSIVE | LK_RETRY); 243 if (error == 0) 244 *vpp = vp; 245 return (error); 246 } 247 248 static int 249 nullfs_quotactl(struct mount *mp, int cmd, uid_t uid, caddr_t arg, 250 struct ucred *cred) 251 { 252 return VFS_QUOTACTL(MOUNTTONULLMOUNT(mp)->nullm_vfs, cmd, uid, arg, cred); 253 } 254 255 static int 256 nullfs_statfs(struct mount *mp, struct statfs *sbp, struct ucred *cred) 257 { 258 int error; 259 struct statfs mstat; 260 261 NULLFSDEBUG("nullfs_statfs(mp = %p, vp = %p)\n", (void *)mp, 262 (void *)MOUNTTONULLMOUNT(mp)->nullm_rootvp); 263 264 bzero(&mstat, sizeof(mstat)); 265 266 error = VFS_STATFS(MOUNTTONULLMOUNT(mp)->nullm_vfs, &mstat, cred); 267 if (error) 268 return (error); 269 270 /* now copy across the "interesting" information and fake the rest */ 271 sbp->f_type = mstat.f_type; 272 sbp->f_flags = mstat.f_flags; 273 sbp->f_bsize = mstat.f_bsize; 274 sbp->f_iosize = mstat.f_iosize; 275 sbp->f_blocks = mstat.f_blocks; 276 sbp->f_bfree = mstat.f_bfree; 277 sbp->f_bavail = mstat.f_bavail; 278 sbp->f_files = mstat.f_files; 279 sbp->f_ffree = mstat.f_ffree; 280 if (sbp != &mp->mnt_stat) { 281 bcopy(&mp->mnt_stat.f_fsid, &sbp->f_fsid, sizeof(sbp->f_fsid)); 282 bcopy(mp->mnt_stat.f_mntfromname, sbp->f_mntfromname, MNAMELEN); 283 } 284 return (0); 285 } 286 287 /* 288 * Implement NFS export tracking 289 */ 290 static int 291 nullfs_checkexp(struct mount *mp, struct sockaddr *nam, int *extflagsp, 292 struct ucred **credanonp) 293 { 294 struct null_mount *xmp = (void *)mp->mnt_data; 295 struct netcred *np; 296 int error; 297 298 np = vfs_export_lookup(mp, &xmp->export, nam); 299 if (np) { 300 *extflagsp = np->netc_exflags; 301 *credanonp = &np->netc_anon; 302 error = 0; 303 } else { 304 error = EACCES; 305 } 306 return(error); 307 #if 0 308 return VFS_CHECKEXP(MOUNTTONULLMOUNT(mp)->nullm_vfs, nam, 309 extflagsp, credanonp); 310 #endif 311 } 312 313 int 314 nullfs_export(struct mount *mp, int op, const struct export_args *export) 315 { 316 struct null_mount *xmp = (void *)mp->mnt_data; 317 int error; 318 319 switch(op) { 320 case MOUNTCTL_SET_EXPORT: 321 error = vfs_export(mp, &xmp->export, export); 322 break; 323 default: 324 error = EOPNOTSUPP; 325 break; 326 } 327 return(error); 328 } 329 330 /* 331 * Pass through file handle conversion functions. 332 */ 333 static int 334 nullfs_vptofh(struct vnode *vp, struct fid *fhp) 335 { 336 return VFS_VPTOFH(vp, fhp); 337 } 338 339 /* 340 * Pass through file handle conversion functions. 341 * 342 * NOTE: currently only HAMMER uses rootvp. HAMMER uses rootvp only 343 * to enforce PFS isolation. 344 */ 345 static int 346 nullfs_fhtovp(struct mount *mp, struct vnode *rootvp, 347 struct fid *fhp, struct vnode **vpp) 348 { 349 struct null_mount *xmp = MOUNTTONULLMOUNT(mp); 350 351 return VFS_FHTOVP(xmp->nullm_vfs, xmp->nullm_rootvp, fhp, vpp); 352 } 353 354 static int 355 nullfs_extattrctl(struct mount *mp, int cmd, const char *attrname, caddr_t arg, 356 struct ucred *cred) 357 { 358 return VFS_EXTATTRCTL(MOUNTTONULLMOUNT(mp)->nullm_vfs, cmd, attrname, 359 arg, cred); 360 } 361 362 363 static struct vfsops null_vfsops = { 364 .vfs_mount = nullfs_mount, 365 .vfs_unmount = nullfs_unmount, 366 .vfs_root = nullfs_root, 367 .vfs_quotactl = nullfs_quotactl, 368 .vfs_statfs = nullfs_statfs, 369 .vfs_sync = vfs_stdsync, 370 .vfs_extattrctl = nullfs_extattrctl, 371 .vfs_fhtovp = nullfs_fhtovp, 372 .vfs_vptofh = nullfs_vptofh, 373 .vfs_checkexp = nullfs_checkexp 374 }; 375 376 VFS_SET(null_vfsops, null, VFCF_LOOPBACK); 377