Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)
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FreeBSD/Linux Kernel Cross Reference
sys/fs/nullfs/null_vfsops.c
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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: releng/9.0/sys/fs/nullfs/null_vfsops.c 226990 2011-11-01 15:41:55Z 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 56 static MALLOC_DEFINE(M_NULLFSMNT, "nullfs_mount", "NULLFS mount structure"); 57 58 static vfs_fhtovp_t nullfs_fhtovp; 59 static vfs_mount_t nullfs_mount; 60 static vfs_quotactl_t nullfs_quotactl; 61 static vfs_root_t nullfs_root; 62 static vfs_sync_t nullfs_sync; 63 static vfs_statfs_t nullfs_statfs; 64 static vfs_unmount_t nullfs_unmount; 65 static vfs_vget_t nullfs_vget; 66 static vfs_extattrctl_t nullfs_extattrctl; 67 68 /* 69 * Mount null layer 70 */ 71 static int 72 nullfs_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 vrele(lowerrootvp); 161 free(xmp, M_NULLFSMNT); /* XXX */ 162 return (error); 163 } 164 165 /* 166 * Keep a held reference to the root vnode. 167 * It is vrele'd in nullfs_unmount. 168 */ 169 nullm_rootvp = vp; 170 nullm_rootvp->v_vflag |= VV_ROOT; 171 xmp->nullm_rootvp = nullm_rootvp; 172 173 /* 174 * Unlock the node (either the lower or the alias) 175 */ 176 VOP_UNLOCK(vp, 0); 177 178 if (NULLVPTOLOWERVP(nullm_rootvp)->v_mount->mnt_flag & MNT_LOCAL) { 179 MNT_ILOCK(mp); 180 mp->mnt_flag |= MNT_LOCAL; 181 MNT_IUNLOCK(mp); 182 } 183 MNT_ILOCK(mp); 184 mp->mnt_kern_flag |= lowerrootvp->v_mount->mnt_kern_flag & MNTK_MPSAFE; 185 MNT_IUNLOCK(mp); 186 mp->mnt_data = xmp; 187 vfs_getnewfsid(mp); 188 189 vfs_mountedfrom(mp, target); 190 191 NULLFSDEBUG("nullfs_mount: lower %s, alias at %s\n", 192 mp->mnt_stat.f_mntfromname, mp->mnt_stat.f_mntonname); 193 return (0); 194 } 195 196 /* 197 * Free reference to null layer 198 */ 199 static int 200 nullfs_unmount(mp, mntflags) 201 struct mount *mp; 202 int mntflags; 203 { 204 void *mntdata; 205 int error; 206 int flags = 0; 207 208 NULLFSDEBUG("nullfs_unmount: mp = %p\n", (void *)mp); 209 210 if (mntflags & MNT_FORCE) 211 flags |= FORCECLOSE; 212 213 /* There is 1 extra root vnode reference (nullm_rootvp). */ 214 error = vflush(mp, 1, flags, curthread); 215 if (error) 216 return (error); 217 218 /* 219 * Finally, throw away the null_mount structure 220 */ 221 mntdata = mp->mnt_data; 222 mp->mnt_data = 0; 223 free(mntdata, M_NULLFSMNT); 224 return 0; 225 } 226 227 static int 228 nullfs_root(mp, flags, vpp) 229 struct mount *mp; 230 int flags; 231 struct vnode **vpp; 232 { 233 struct vnode *vp; 234 235 NULLFSDEBUG("nullfs_root(mp = %p, vp = %p->%p)\n", (void *)mp, 236 (void *)MOUNTTONULLMOUNT(mp)->nullm_rootvp, 237 (void *)NULLVPTOLOWERVP(MOUNTTONULLMOUNT(mp)->nullm_rootvp)); 238 239 /* 240 * Return locked reference to root. 241 */ 242 vp = MOUNTTONULLMOUNT(mp)->nullm_rootvp; 243 VREF(vp); 244 245 ASSERT_VOP_UNLOCKED(vp, "root vnode is locked"); 246 vn_lock(vp, flags | LK_RETRY); 247 *vpp = vp; 248 return 0; 249 } 250 251 static int 252 nullfs_quotactl(mp, cmd, uid, arg) 253 struct mount *mp; 254 int cmd; 255 uid_t uid; 256 void *arg; 257 { 258 return VFS_QUOTACTL(MOUNTTONULLMOUNT(mp)->nullm_vfs, cmd, uid, arg); 259 } 260 261 static int 262 nullfs_statfs(mp, sbp) 263 struct mount *mp; 264 struct statfs *sbp; 265 { 266 int error; 267 struct statfs mstat; 268 269 NULLFSDEBUG("nullfs_statfs(mp = %p, vp = %p->%p)\n", (void *)mp, 270 (void *)MOUNTTONULLMOUNT(mp)->nullm_rootvp, 271 (void *)NULLVPTOLOWERVP(MOUNTTONULLMOUNT(mp)->nullm_rootvp)); 272 273 bzero(&mstat, sizeof(mstat)); 274 275 error = VFS_STATFS(MOUNTTONULLMOUNT(mp)->nullm_vfs, &mstat); 276 if (error) 277 return (error); 278 279 /* now copy across the "interesting" information and fake the rest */ 280 sbp->f_type = mstat.f_type; 281 sbp->f_flags = mstat.f_flags; 282 sbp->f_bsize = mstat.f_bsize; 283 sbp->f_iosize = mstat.f_iosize; 284 sbp->f_blocks = mstat.f_blocks; 285 sbp->f_bfree = mstat.f_bfree; 286 sbp->f_bavail = mstat.f_bavail; 287 sbp->f_files = mstat.f_files; 288 sbp->f_ffree = mstat.f_ffree; 289 return (0); 290 } 291 292 static int 293 nullfs_sync(mp, waitfor) 294 struct mount *mp; 295 int waitfor; 296 { 297 /* 298 * XXX - Assumes no data cached at null layer. 299 */ 300 return (0); 301 } 302 303 static int 304 nullfs_vget(mp, ino, flags, vpp) 305 struct mount *mp; 306 ino_t ino; 307 int flags; 308 struct vnode **vpp; 309 { 310 int error; 311 error = VFS_VGET(MOUNTTONULLMOUNT(mp)->nullm_vfs, ino, flags, vpp); 312 if (error) 313 return (error); 314 315 return (null_nodeget(mp, *vpp, vpp)); 316 } 317 318 static int 319 nullfs_fhtovp(mp, fidp, flags, vpp) 320 struct mount *mp; 321 struct fid *fidp; 322 int flags; 323 struct vnode **vpp; 324 { 325 int error; 326 error = VFS_FHTOVP(MOUNTTONULLMOUNT(mp)->nullm_vfs, fidp, LK_EXCLUSIVE, 327 vpp); 328 if (error) 329 return (error); 330 331 return (null_nodeget(mp, *vpp, vpp)); 332 } 333 334 static int 335 nullfs_extattrctl(mp, cmd, filename_vp, namespace, attrname) 336 struct mount *mp; 337 int cmd; 338 struct vnode *filename_vp; 339 int namespace; 340 const char *attrname; 341 { 342 return VFS_EXTATTRCTL(MOUNTTONULLMOUNT(mp)->nullm_vfs, cmd, filename_vp, 343 namespace, attrname); 344 } 345 346 347 static struct vfsops null_vfsops = { 348 .vfs_extattrctl = nullfs_extattrctl, 349 .vfs_fhtovp = nullfs_fhtovp, 350 .vfs_init = nullfs_init, 351 .vfs_mount = nullfs_mount, 352 .vfs_quotactl = nullfs_quotactl, 353 .vfs_root = nullfs_root, 354 .vfs_statfs = nullfs_statfs, 355 .vfs_sync = nullfs_sync, 356 .vfs_uninit = nullfs_uninit, 357 .vfs_unmount = nullfs_unmount, 358 .vfs_vget = nullfs_vget, 359 }; 360 361 VFS_SET(null_vfsops, nullfs, VFCF_LOOPBACK);
Cache object: ff3e8cc3e38d7edc839212d5297c04f8
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