1 /*- 2 * SPDX-License-Identifier: BSD-3-Clause 3 * 4 * Copyright (c) 1992, 1993 5 * The Regents of the University of California. All rights reserved. 6 * 7 * This code is derived from software donated to Berkeley by 8 * Jan-Simon Pendry. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 3. Neither the name of the University nor the names of its contributors 19 * may be used to endorse or promote products derived from this software 20 * without specific prior written permission. 21 * 22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 25 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32 * SUCH DAMAGE. 33 */ 34 35 #include <sys/param.h> 36 #include <sys/systm.h> 37 #include <sys/kernel.h> 38 #include <sys/lock.h> 39 #include <sys/rwlock.h> 40 #include <sys/malloc.h> 41 #include <sys/mount.h> 42 #include <sys/proc.h> 43 #include <sys/vnode.h> 44 #include <sys/smr.h> 45 46 #include <fs/nullfs/null.h> 47 48 #include <vm/uma.h> 49 50 VFS_SMR_DECLARE; 51 52 /* 53 * Null layer cache: 54 * Each cache entry holds a reference to the lower vnode 55 * along with a pointer to the alias vnode. When an 56 * entry is added the lower vnode is VREF'd. When the 57 * alias is removed the lower vnode is vrele'd. 58 */ 59 60 #define NULL_NHASH(vp) (&null_node_hashtbl[vfs_hash_index(vp) & null_hash_mask]) 61 62 static CK_LIST_HEAD(null_node_hashhead, null_node) *null_node_hashtbl; 63 static struct rwlock null_hash_lock; 64 static u_long null_hash_mask; 65 66 static MALLOC_DEFINE(M_NULLFSHASH, "nullfs_hash", "NULLFS hash table"); 67 uma_zone_t __read_mostly null_node_zone; 68 69 static void null_hashins(struct mount *, struct null_node *); 70 71 /* 72 * Initialise cache headers 73 */ 74 int 75 nullfs_init(struct vfsconf *vfsp) 76 { 77 78 null_node_hashtbl = hashinit(desiredvnodes, M_NULLFSHASH, 79 &null_hash_mask); 80 rw_init(&null_hash_lock, "nullhs"); 81 null_node_zone = uma_zcreate("nullfs node", sizeof(struct null_node), 82 NULL, NULL, NULL, NULL, 0, UMA_ZONE_ZINIT); 83 VFS_SMR_ZONE_SET(null_node_zone); 84 85 return (0); 86 } 87 88 int 89 nullfs_uninit(struct vfsconf *vfsp) 90 { 91 92 uma_zdestroy(null_node_zone); 93 rw_destroy(&null_hash_lock); 94 hashdestroy(null_node_hashtbl, M_NULLFSHASH, null_hash_mask); 95 return (0); 96 } 97 98 /* 99 * Return a VREF'ed alias for lower vnode if already exists, else 0. 100 * Lower vnode should be locked on entry and will be left locked on exit. 101 */ 102 static struct vnode * 103 null_hashget_locked(struct mount *mp, struct vnode *lowervp) 104 { 105 struct null_node_hashhead *hd; 106 struct null_node *a; 107 struct vnode *vp; 108 109 ASSERT_VOP_LOCKED(lowervp, __func__); 110 rw_assert(&null_hash_lock, RA_LOCKED); 111 112 /* 113 * Find hash base, and then search the (two-way) linked 114 * list looking for a null_node structure which is referencing 115 * the lower vnode. If found, the increment the null_node 116 * reference count (but NOT the lower vnode's VREF counter). 117 */ 118 hd = NULL_NHASH(lowervp); 119 CK_LIST_FOREACH(a, hd, null_hash) { 120 if (a->null_lowervp != lowervp) 121 continue; 122 /* 123 * Since we have the lower node locked the nullfs 124 * node can not be in the process of recycling. If 125 * it had been recycled before we grabed the lower 126 * lock it would not have been found on the hash. 127 */ 128 vp = NULLTOV(a); 129 VNPASS(!VN_IS_DOOMED(vp), vp); 130 if (vp->v_mount != mp) 131 continue; 132 vref(vp); 133 return (vp); 134 } 135 return (NULL); 136 } 137 138 struct vnode * 139 null_hashget(struct mount *mp, struct vnode *lowervp) 140 { 141 struct null_node_hashhead *hd; 142 struct null_node *a; 143 struct vnode *vp; 144 enum vgetstate vs; 145 146 ASSERT_VOP_LOCKED(lowervp, "null_hashget"); 147 rw_assert(&null_hash_lock, RA_UNLOCKED); 148 149 vfs_smr_enter(); 150 hd = NULL_NHASH(lowervp); 151 CK_LIST_FOREACH(a, hd, null_hash) { 152 if (a->null_lowervp != lowervp) 153 continue; 154 /* 155 * See null_hashget_locked as to why the nullfs vnode can't be 156 * doomed here. 157 */ 158 vp = NULLTOV(a); 159 VNPASS(!VN_IS_DOOMED(vp), vp); 160 if (vp->v_mount != mp) 161 continue; 162 vs = vget_prep_smr(vp); 163 vfs_smr_exit(); 164 VNPASS(vs != VGET_NONE, vp); 165 vget_finish_ref(vp, vs); 166 return (vp); 167 } 168 vfs_smr_exit(); 169 return (NULL); 170 } 171 172 static void 173 null_hashins(struct mount *mp, struct null_node *xp) 174 { 175 struct null_node_hashhead *hd; 176 #ifdef INVARIANTS 177 struct null_node *oxp; 178 #endif 179 180 rw_assert(&null_hash_lock, RA_WLOCKED); 181 182 hd = NULL_NHASH(xp->null_lowervp); 183 #ifdef INVARIANTS 184 CK_LIST_FOREACH(oxp, hd, null_hash) { 185 if (oxp->null_lowervp == xp->null_lowervp && 186 NULLTOV(oxp)->v_mount == mp) { 187 VNASSERT(0, NULLTOV(oxp), 188 ("vnode already in hash")); 189 } 190 } 191 #endif 192 CK_LIST_INSERT_HEAD(hd, xp, null_hash); 193 } 194 195 static void 196 null_destroy_proto(struct vnode *vp, void *xp) 197 { 198 199 lockmgr(&vp->v_lock, LK_EXCLUSIVE, NULL); 200 VI_LOCK(vp); 201 vp->v_data = NULL; 202 vp->v_vnlock = &vp->v_lock; 203 vp->v_op = &dead_vnodeops; 204 VI_UNLOCK(vp); 205 vgone(vp); 206 vput(vp); 207 uma_zfree_smr(null_node_zone, xp); 208 } 209 210 /* 211 * Make a new or get existing nullfs node. 212 * Vp is the alias vnode, lowervp is the lower vnode. 213 * 214 * The lowervp assumed to be locked and having "spare" reference. This routine 215 * vrele lowervp if nullfs node was taken from hash. Otherwise it "transfers" 216 * the caller's "spare" reference to created nullfs vnode. 217 */ 218 int 219 null_nodeget(struct mount *mp, struct vnode *lowervp, struct vnode **vpp) 220 { 221 struct null_node *xp; 222 struct vnode *vp; 223 int error; 224 225 ASSERT_VOP_LOCKED(lowervp, "lowervp"); 226 VNPASS(lowervp->v_usecount > 0, lowervp); 227 228 /* Lookup the hash firstly. */ 229 *vpp = null_hashget(mp, lowervp); 230 if (*vpp != NULL) { 231 vrele(lowervp); 232 return (0); 233 } 234 235 /* 236 * We do not serialize vnode creation, instead we will check for 237 * duplicates later, when adding new vnode to hash. 238 * Note that duplicate can only appear in hash if the lowervp is 239 * locked LK_SHARED. 240 */ 241 xp = uma_zalloc_smr(null_node_zone, M_WAITOK); 242 243 error = getnewvnode("nullfs", mp, &null_vnodeops, &vp); 244 if (error) { 245 vput(lowervp); 246 uma_zfree_smr(null_node_zone, xp); 247 return (error); 248 } 249 250 VNPASS(vp->v_object == NULL, vp); 251 VNPASS((vn_irflag_read(vp) & VIRF_PGREAD) == 0, vp); 252 253 rw_wlock(&null_hash_lock); 254 xp->null_vnode = vp; 255 xp->null_lowervp = lowervp; 256 xp->null_flags = 0; 257 vp->v_type = lowervp->v_type; 258 vp->v_data = xp; 259 vp->v_vnlock = lowervp->v_vnlock; 260 *vpp = null_hashget_locked(mp, lowervp); 261 if (*vpp != NULL) { 262 rw_wunlock(&null_hash_lock); 263 vrele(lowervp); 264 null_destroy_proto(vp, xp); 265 return (0); 266 } 267 268 /* 269 * We might miss the case where lower vnode sets VIRF_PGREAD 270 * some time after construction, which is typical case. 271 * null_open rechecks. 272 */ 273 if ((vn_irflag_read(lowervp) & VIRF_PGREAD) != 0) { 274 MPASS(lowervp->v_object != NULL); 275 vp->v_object = lowervp->v_object; 276 vn_irflag_set(vp, VIRF_PGREAD); 277 } 278 if ((vn_irflag_read(lowervp) & VIRF_INOTIFY) != 0) 279 vn_irflag_set(vp, VIRF_INOTIFY); 280 if ((vn_irflag_read(lowervp) & VIRF_INOTIFY_PARENT) != 0) 281 vn_irflag_set(vp, VIRF_INOTIFY_PARENT); 282 if (lowervp == MOUNTTONULLMOUNT(mp)->nullm_lowerrootvp) 283 vp->v_vflag |= VV_ROOT; 284 285 error = insmntque1(vp, mp); 286 if (error != 0) { 287 rw_wunlock(&null_hash_lock); 288 vput(lowervp); 289 vp->v_object = NULL; 290 null_destroy_proto(vp, xp); 291 return (error); 292 } 293 294 vn_set_state(vp, VSTATE_CONSTRUCTED); 295 null_hashins(mp, xp); 296 rw_wunlock(&null_hash_lock); 297 *vpp = vp; 298 299 return (0); 300 } 301 302 /* 303 * Remove node from hash. 304 */ 305 void 306 null_hashrem(struct null_node *xp) 307 { 308 309 rw_wlock(&null_hash_lock); 310 CK_LIST_REMOVE(xp, null_hash); 311 rw_wunlock(&null_hash_lock); 312 } 313 314 #ifdef DIAGNOSTIC 315 316 struct vnode * 317 null_checkvp(struct vnode *vp, char *fil, int lno) 318 { 319 struct null_node *a = VTONULL(vp); 320 321 #ifdef notyet 322 /* 323 * Can't do this check because vop_reclaim runs 324 * with a funny vop vector. 325 */ 326 if (vp->v_op != null_vnodeop_p) { 327 printf ("null_checkvp: on non-null-node\n"); 328 panic("null_checkvp"); 329 } 330 #endif 331 if (a->null_lowervp == NULL) { 332 /* Should never happen */ 333 panic("null_checkvp %p", vp); 334 } 335 VI_LOCK_FLAGS(a->null_lowervp, MTX_DUPOK); 336 if (a->null_lowervp->v_usecount < 1) 337 panic ("null with unref'ed lowervp, vp %p lvp %p", 338 vp, a->null_lowervp); 339 VI_UNLOCK(a->null_lowervp); 340 #ifdef notyet 341 printf("null %x/%d -> %x/%d [%s, %d]\n", 342 NULLTOV(a), vrefcnt(NULLTOV(a)), 343 a->null_lowervp, vrefcnt(a->null_lowervp), 344 fil, lno); 345 #endif 346 return (a->null_lowervp); 347 } 348 #endif 349