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 size_t size; 78 struct nlookupdata nd; 79 fhandle_t fh; 80 81 NULLFSDEBUG("nullfs_mount(mp = %p)\n", (void *)mp); 82 83 /* 84 * Get argument 85 */ 86 error = copyin(data, (caddr_t)&args, sizeof(struct null_args)); 87 if (error) 88 return (error); 89 90 /* 91 * XXX: Should we process mount export info ? 92 * If not, returning zero here is enough as the actual ro/rw update is 93 * being done in sys_mount(). 94 */ 95 if (mp->mnt_flag & MNT_UPDATE) { 96 xmp = MOUNTTONULLMOUNT(mp); 97 error = vfs_export(mp, &xmp->export, &args.export); 98 return (error); 99 } 100 101 /* 102 * Find lower node 103 */ 104 rootvp = NULL; 105 error = nlookup_init(&nd, args.target, UIO_USERSPACE, NLC_FOLLOW); 106 if (error) 107 goto fail1; 108 error = nlookup(&nd); 109 if (error) 110 goto fail2; 111 error = cache_vget(&nd.nl_nch, nd.nl_cred, LK_EXCLUSIVE, &rootvp); 112 if (error) 113 goto fail2; 114 115 xmp = (struct null_mount *) kmalloc(sizeof(struct null_mount), 116 M_NULLFSMNT, M_WAITOK | M_ZERO); 117 118 /* 119 * Save reference to underlying FS 120 * 121 * As lite stacking enters the scene, the old way of doing this 122 * -- via the vnode -- is not good enough anymore. Use the 123 * underlying filesystem's namecache handle as our mount point 124 * root, adjusting the mount to point to us. 125 * 126 * NCF_ISMOUNTPT is normally set on the mount point, but we also 127 * want to set it on the base directory being mounted to prevent 128 * that directory from being destroyed out from under the nullfs 129 * mount. 130 * 131 * The forwarding mount pointer (xmp->nullm_vfs) must be set to 132 * the actual target filesystem. If the target filesystem was 133 * resolved via a nullfs mount nd.nl_nch.mount will be pointing 134 * to the nullfs mount structure instead of the target filesystem, 135 * which would otherwise cause the mount VOPS and VFSOPS to recurse 136 * endlessly. If we are mounting via a nullfs mount we inherit 137 * its read-only state, if set. 138 */ 139 xmp->nullm_vfs = nd.nl_nch.mount; 140 if (xmp->nullm_vfs != rootvp->v_mount) { 141 if (xmp->nullm_vfs->mnt_flag & MNT_RDONLY) 142 mp->mnt_flag |= MNT_RDONLY; 143 xmp->nullm_vfs = rootvp->v_mount; 144 } 145 146 /* 147 * ncmountpt is the parent glue. When mounting a nullfs via a nullfs 148 * we retain the parent nullfs to create a unique chain tuple. 149 */ 150 mp->mnt_ncmountpt = nd.nl_nch; 151 cache_changemount(&mp->mnt_ncmountpt, mp); 152 mp->mnt_ncmountpt.ncp->nc_flag |= NCF_ISMOUNTPT; 153 cache_unlock(&mp->mnt_ncmountpt); 154 cache_zero(&nd.nl_nch); 155 nlookup_done(&nd); 156 157 vfs_add_vnodeops(mp, &null_vnode_vops, &mp->mnt_vn_norm_ops); 158 159 vn_unlock(rootvp); /* leave reference intact */ 160 161 /* 162 * Keep a held reference to the root vnode. 163 * It is vrele'd in nullfs_unmount. 164 */ 165 xmp->nullm_rootvp = rootvp; 166 /* 167 * XXX What's the proper safety condition for querying 168 * the underlying mount? Is this flag tuning necessary 169 * at all? 170 */ 171 if (xmp->nullm_vfs->mnt_flag & MNT_LOCAL) 172 mp->mnt_flag |= MNT_LOCAL; 173 mp->mnt_data = (qaddr_t) xmp; 174 175 /* 176 * Try to create a unique but non-random fsid for the nullfs to 177 * allow it to be exported via NFS. 178 */ 179 bzero(&fh, sizeof(fh)); 180 fh.fh_fsid = rootvp->v_mount->mnt_stat.f_fsid; 181 if (VFS_VPTOFH(rootvp, &fh.fh_fid) == 0) { 182 fh.fh_fsid.val[1] ^= crc32(&fh.fh_fid, sizeof(fh.fh_fid)); 183 vfs_setfsid(mp, &fh.fh_fsid); 184 } else { 185 vfs_getnewfsid(mp); 186 } 187 188 (void) copyinstr(args.target, mp->mnt_stat.f_mntfromname, MNAMELEN - 1, 189 &size); 190 bzero(mp->mnt_stat.f_mntfromname + size, MNAMELEN - size); 191 (void)nullfs_statfs(mp, &mp->mnt_stat, cred); 192 NULLFSDEBUG("nullfs_mount: lower %s, alias at %s\n", 193 mp->mnt_stat.f_mntfromname, mp->mnt_stat.f_mntfromname); 194 195 /* 196 * So unmount won't complain about namecache refs still existing 197 */ 198 mp->mnt_kern_flag |= MNTK_NCALIASED; 199 return (0); 200 fail2: 201 nlookup_done(&nd); 202 fail1: 203 return (error); 204 } 205 206 /* 207 * Free reference to null layer 208 */ 209 static int 210 nullfs_unmount(struct mount *mp, int mntflags) 211 { 212 struct null_mount *xmp; 213 int flags = 0; 214 215 NULLFSDEBUG("nullfs_unmount: mp = %p\n", (void *)mp); 216 217 if (mntflags & MNT_FORCE) 218 flags |= FORCECLOSE; 219 220 /* 221 * Finally, throw away the null_mount structure 222 */ 223 xmp = (void *)mp->mnt_data; 224 mp->mnt_data = 0; 225 if (xmp->nullm_rootvp) { 226 vrele(xmp->nullm_rootvp); 227 xmp->nullm_rootvp = NULL; 228 } 229 kfree(xmp, M_NULLFSMNT); 230 return 0; 231 } 232 233 static int 234 nullfs_root(struct mount *mp, struct vnode **vpp) 235 { 236 struct vnode *vp; 237 int error; 238 239 NULLFSDEBUG("nullfs_root(mp = %p, vp = %p)\n", (void *)mp, 240 (void *)MOUNTTONULLMOUNT(mp)->nullm_rootvp); 241 242 /* 243 * Return locked reference to root. 244 */ 245 vp = MOUNTTONULLMOUNT(mp)->nullm_rootvp; 246 error = vget(vp, LK_EXCLUSIVE | LK_RETRY); 247 if (error == 0) 248 *vpp = vp; 249 return (error); 250 } 251 252 static int 253 nullfs_quotactl(struct mount *mp, int cmd, uid_t uid, caddr_t arg, 254 struct ucred *cred) 255 { 256 return VFS_QUOTACTL(MOUNTTONULLMOUNT(mp)->nullm_vfs, cmd, uid, arg, cred); 257 } 258 259 static int 260 nullfs_statfs(struct mount *mp, struct statfs *sbp, struct ucred *cred) 261 { 262 int error; 263 struct statfs mstat; 264 265 NULLFSDEBUG("nullfs_statfs(mp = %p, vp = %p)\n", (void *)mp, 266 (void *)MOUNTTONULLMOUNT(mp)->nullm_rootvp); 267 268 bzero(&mstat, sizeof(mstat)); 269 270 error = VFS_STATFS(MOUNTTONULLMOUNT(mp)->nullm_vfs, &mstat, cred); 271 if (error) 272 return (error); 273 274 /* now copy across the "interesting" information and fake the rest */ 275 sbp->f_type = mstat.f_type; 276 sbp->f_flags = mstat.f_flags; 277 sbp->f_bsize = mstat.f_bsize; 278 sbp->f_iosize = mstat.f_iosize; 279 sbp->f_blocks = mstat.f_blocks; 280 sbp->f_bfree = mstat.f_bfree; 281 sbp->f_bavail = mstat.f_bavail; 282 sbp->f_files = mstat.f_files; 283 sbp->f_ffree = mstat.f_ffree; 284 if (sbp != &mp->mnt_stat) { 285 bcopy(&mp->mnt_stat.f_fsid, &sbp->f_fsid, sizeof(sbp->f_fsid)); 286 bcopy(mp->mnt_stat.f_mntfromname, sbp->f_mntfromname, MNAMELEN); 287 } 288 return (0); 289 } 290 291 /* 292 * Implement NFS export tracking 293 */ 294 static int 295 nullfs_checkexp(struct mount *mp, struct sockaddr *nam, int *extflagsp, 296 struct ucred **credanonp) 297 { 298 struct null_mount *xmp = (void *)mp->mnt_data; 299 struct netcred *np; 300 int error; 301 302 np = vfs_export_lookup(mp, &xmp->export, nam); 303 if (np) { 304 *extflagsp = np->netc_exflags; 305 *credanonp = &np->netc_anon; 306 error = 0; 307 } else { 308 error = EACCES; 309 } 310 return(error); 311 #if 0 312 return VFS_CHECKEXP(MOUNTTONULLMOUNT(mp)->nullm_vfs, nam, 313 extflagsp, credanonp); 314 #endif 315 } 316 317 int 318 nullfs_export(struct mount *mp, int op, const struct export_args *export) 319 { 320 struct null_mount *xmp = (void *)mp->mnt_data; 321 int error; 322 323 switch(op) { 324 case MOUNTCTL_SET_EXPORT: 325 error = vfs_export(mp, &xmp->export, export); 326 break; 327 default: 328 error = EOPNOTSUPP; 329 break; 330 } 331 return(error); 332 } 333 334 /* 335 * Pass through file handle conversion functions. 336 */ 337 static int 338 nullfs_vptofh(struct vnode *vp, struct fid *fhp) 339 { 340 return VFS_VPTOFH(vp, fhp); 341 } 342 343 /* 344 * Pass through file handle conversion functions. 345 * 346 * NOTE: currently only HAMMER uses rootvp. HAMMER uses rootvp only 347 * to enforce PFS isolation. 348 */ 349 static int 350 nullfs_fhtovp(struct mount *mp, struct vnode *rootvp, 351 struct fid *fhp, struct vnode **vpp) 352 { 353 struct null_mount *xmp = MOUNTTONULLMOUNT(mp); 354 355 return VFS_FHTOVP(xmp->nullm_vfs, xmp->nullm_rootvp, fhp, vpp); 356 } 357 358 static int 359 nullfs_extattrctl(struct mount *mp, int cmd, const char *attrname, caddr_t arg, 360 struct ucred *cred) 361 { 362 return VFS_EXTATTRCTL(MOUNTTONULLMOUNT(mp)->nullm_vfs, cmd, attrname, 363 arg, cred); 364 } 365 366 367 static struct vfsops null_vfsops = { 368 .vfs_mount = nullfs_mount, 369 .vfs_unmount = nullfs_unmount, 370 .vfs_root = nullfs_root, 371 .vfs_quotactl = nullfs_quotactl, 372 .vfs_statfs = nullfs_statfs, 373 .vfs_sync = vfs_stdsync, 374 .vfs_extattrctl = nullfs_extattrctl, 375 .vfs_fhtovp = nullfs_fhtovp, 376 .vfs_vptofh = nullfs_vptofh, 377 .vfs_checkexp = nullfs_checkexp 378 }; 379 380 VFS_SET(null_vfsops, null, VFCF_LOOPBACK); 381