1 /* $NetBSD: tmpfs_vfsops.c,v 1.10 2005/12/11 12:24:29 christos Exp $ */ 2 3 /*- 4 * SPDX-License-Identifier: BSD-2-Clause-NetBSD 5 * 6 * Copyright (c) 2005 The NetBSD Foundation, Inc. 7 * All rights reserved. 8 * 9 * This code is derived from software contributed to The NetBSD Foundation 10 * by Julio M. Merino Vidal, developed as part of Google's Summer of Code 11 * 2005 program. 12 * 13 * Redistribution and use in source and binary forms, with or without 14 * modification, are permitted provided that the following conditions 15 * are met: 16 * 1. Redistributions of source code must retain the above copyright 17 * notice, this list of conditions and the following disclaimer. 18 * 2. Redistributions in binary form must reproduce the above copyright 19 * notice, this list of conditions and the following disclaimer in the 20 * documentation and/or other materials provided with the distribution. 21 * 22 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 23 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 24 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 25 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 26 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 27 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 28 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 29 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 30 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 31 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 32 * POSSIBILITY OF SUCH DAMAGE. 33 */ 34 35 /* 36 * Efficient memory file system. 37 * 38 * tmpfs is a file system that uses FreeBSD's virtual memory 39 * sub-system to store file data and metadata in an efficient way. 40 * This means that it does not follow the structure of an on-disk file 41 * system because it simply does not need to. Instead, it uses 42 * memory-specific data structures and algorithms to automatically 43 * allocate and release resources. 44 */ 45 #include <sys/cdefs.h> 46 __FBSDID("$FreeBSD$"); 47 48 #include <sys/param.h> 49 #include <sys/systm.h> 50 #include <sys/dirent.h> 51 #include <sys/limits.h> 52 #include <sys/lock.h> 53 #include <sys/mount.h> 54 #include <sys/mutex.h> 55 #include <sys/proc.h> 56 #include <sys/jail.h> 57 #include <sys/kernel.h> 58 #include <sys/rwlock.h> 59 #include <sys/stat.h> 60 #include <sys/sysctl.h> 61 #include <sys/vnode.h> 62 63 #include <vm/vm.h> 64 #include <vm/vm_object.h> 65 #include <vm/vm_param.h> 66 67 #include <fs/tmpfs/tmpfs.h> 68 69 /* 70 * Default permission for root node 71 */ 72 #define TMPFS_DEFAULT_ROOT_MODE (S_IRWXU|S_IRGRP|S_IXGRP|S_IROTH|S_IXOTH) 73 74 MALLOC_DEFINE(M_TMPFSMNT, "tmpfs mount", "tmpfs mount structures"); 75 MALLOC_DEFINE(M_TMPFSNAME, "tmpfs name", "tmpfs file names"); 76 77 static int tmpfs_mount(struct mount *); 78 static int tmpfs_unmount(struct mount *, int); 79 static int tmpfs_root(struct mount *, int flags, struct vnode **); 80 static int tmpfs_fhtovp(struct mount *, struct fid *, int, 81 struct vnode **); 82 static int tmpfs_statfs(struct mount *, struct statfs *); 83 static void tmpfs_susp_clean(struct mount *); 84 85 static const char *tmpfs_opts[] = { 86 "from", "size", "maxfilesize", "inodes", "uid", "gid", "mode", "export", 87 "union", "nonc", NULL 88 }; 89 90 static const char *tmpfs_updateopts[] = { 91 "from", "export", NULL 92 }; 93 94 static int 95 tmpfs_node_ctor(void *mem, int size, void *arg, int flags) 96 { 97 struct tmpfs_node *node = (struct tmpfs_node *)mem; 98 99 node->tn_gen++; 100 node->tn_size = 0; 101 node->tn_status = 0; 102 node->tn_flags = 0; 103 node->tn_links = 0; 104 node->tn_vnode = NULL; 105 node->tn_vpstate = 0; 106 107 return (0); 108 } 109 110 static void 111 tmpfs_node_dtor(void *mem, int size, void *arg) 112 { 113 struct tmpfs_node *node = (struct tmpfs_node *)mem; 114 node->tn_type = VNON; 115 } 116 117 static int 118 tmpfs_node_init(void *mem, int size, int flags) 119 { 120 struct tmpfs_node *node = (struct tmpfs_node *)mem; 121 node->tn_id = 0; 122 123 mtx_init(&node->tn_interlock, "tmpfs node interlock", NULL, MTX_DEF); 124 node->tn_gen = arc4random(); 125 126 return (0); 127 } 128 129 static void 130 tmpfs_node_fini(void *mem, int size) 131 { 132 struct tmpfs_node *node = (struct tmpfs_node *)mem; 133 134 mtx_destroy(&node->tn_interlock); 135 } 136 137 static int 138 tmpfs_mount(struct mount *mp) 139 { 140 const size_t nodes_per_page = howmany(PAGE_SIZE, 141 sizeof(struct tmpfs_dirent) + sizeof(struct tmpfs_node)); 142 struct tmpfs_mount *tmp; 143 struct tmpfs_node *root; 144 int error; 145 bool nonc; 146 /* Size counters. */ 147 u_quad_t pages; 148 off_t nodes_max, size_max, maxfilesize; 149 150 /* Root node attributes. */ 151 uid_t root_uid; 152 gid_t root_gid; 153 mode_t root_mode; 154 155 struct vattr va; 156 157 if (vfs_filteropt(mp->mnt_optnew, tmpfs_opts)) 158 return (EINVAL); 159 160 if (mp->mnt_flag & MNT_UPDATE) { 161 /* Only support update mounts for certain options. */ 162 if (vfs_filteropt(mp->mnt_optnew, tmpfs_updateopts) != 0) 163 return (EOPNOTSUPP); 164 if (vfs_flagopt(mp->mnt_optnew, "ro", NULL, 0) != 165 ((struct tmpfs_mount *)mp->mnt_data)->tm_ronly) 166 return (EOPNOTSUPP); 167 return (0); 168 } 169 170 vn_lock(mp->mnt_vnodecovered, LK_SHARED | LK_RETRY); 171 error = VOP_GETATTR(mp->mnt_vnodecovered, &va, mp->mnt_cred); 172 VOP_UNLOCK(mp->mnt_vnodecovered, 0); 173 if (error) 174 return (error); 175 176 if (mp->mnt_cred->cr_ruid != 0 || 177 vfs_scanopt(mp->mnt_optnew, "gid", "%d", &root_gid) != 1) 178 root_gid = va.va_gid; 179 if (mp->mnt_cred->cr_ruid != 0 || 180 vfs_scanopt(mp->mnt_optnew, "uid", "%d", &root_uid) != 1) 181 root_uid = va.va_uid; 182 if (mp->mnt_cred->cr_ruid != 0 || 183 vfs_scanopt(mp->mnt_optnew, "mode", "%ho", &root_mode) != 1) 184 root_mode = va.va_mode; 185 if (vfs_getopt_size(mp->mnt_optnew, "inodes", &nodes_max) != 0) 186 nodes_max = 0; 187 if (vfs_getopt_size(mp->mnt_optnew, "size", &size_max) != 0) 188 size_max = 0; 189 if (vfs_getopt_size(mp->mnt_optnew, "maxfilesize", &maxfilesize) != 0) 190 maxfilesize = 0; 191 nonc = vfs_getopt(mp->mnt_optnew, "nonc", NULL, NULL) == 0; 192 193 /* Do not allow mounts if we do not have enough memory to preserve 194 * the minimum reserved pages. */ 195 if (tmpfs_mem_avail() < TMPFS_PAGES_MINRESERVED) 196 return (ENOSPC); 197 198 /* Get the maximum number of memory pages this file system is 199 * allowed to use, based on the maximum size the user passed in 200 * the mount structure. A value of zero is treated as if the 201 * maximum available space was requested. */ 202 if (size_max == 0 || size_max > OFF_MAX - PAGE_SIZE || 203 (SIZE_MAX < OFF_MAX && size_max / PAGE_SIZE >= SIZE_MAX)) 204 pages = SIZE_MAX; 205 else { 206 size_max = roundup(size_max, PAGE_SIZE); 207 pages = howmany(size_max, PAGE_SIZE); 208 } 209 MPASS(pages > 0); 210 211 if (nodes_max <= 3) { 212 if (pages < INT_MAX / nodes_per_page) 213 nodes_max = pages * nodes_per_page; 214 else 215 nodes_max = INT_MAX; 216 } 217 if (nodes_max > INT_MAX) 218 nodes_max = INT_MAX; 219 MPASS(nodes_max >= 3); 220 221 /* Allocate the tmpfs mount structure and fill it. */ 222 tmp = (struct tmpfs_mount *)malloc(sizeof(struct tmpfs_mount), 223 M_TMPFSMNT, M_WAITOK | M_ZERO); 224 225 mtx_init(&tmp->tm_allnode_lock, "tmpfs allnode lock", NULL, MTX_DEF); 226 tmp->tm_nodes_max = nodes_max; 227 tmp->tm_nodes_inuse = 0; 228 tmp->tm_refcount = 1; 229 tmp->tm_maxfilesize = maxfilesize > 0 ? maxfilesize : OFF_MAX; 230 LIST_INIT(&tmp->tm_nodes_used); 231 232 tmp->tm_pages_max = pages; 233 tmp->tm_pages_used = 0; 234 new_unrhdr64(&tmp->tm_ino_unr, 2); 235 tmp->tm_dirent_pool = uma_zcreate("TMPFS dirent", 236 sizeof(struct tmpfs_dirent), NULL, NULL, NULL, NULL, 237 UMA_ALIGN_PTR, 0); 238 tmp->tm_node_pool = uma_zcreate("TMPFS node", 239 sizeof(struct tmpfs_node), tmpfs_node_ctor, tmpfs_node_dtor, 240 tmpfs_node_init, tmpfs_node_fini, UMA_ALIGN_PTR, 0); 241 tmp->tm_ronly = (mp->mnt_flag & MNT_RDONLY) != 0; 242 tmp->tm_nonc = nonc; 243 244 /* Allocate the root node. */ 245 error = tmpfs_alloc_node(mp, tmp, VDIR, root_uid, root_gid, 246 root_mode & ALLPERMS, NULL, NULL, VNOVAL, &root); 247 248 if (error != 0 || root == NULL) { 249 uma_zdestroy(tmp->tm_node_pool); 250 uma_zdestroy(tmp->tm_dirent_pool); 251 free(tmp, M_TMPFSMNT); 252 return (error); 253 } 254 KASSERT(root->tn_id == 2, 255 ("tmpfs root with invalid ino: %ju", (uintmax_t)root->tn_id)); 256 tmp->tm_root = root; 257 258 MNT_ILOCK(mp); 259 mp->mnt_flag |= MNT_LOCAL; 260 mp->mnt_kern_flag |= MNTK_LOOKUP_SHARED | MNTK_EXTENDED_SHARED; 261 MNT_IUNLOCK(mp); 262 263 mp->mnt_data = tmp; 264 mp->mnt_stat.f_namemax = MAXNAMLEN; 265 vfs_getnewfsid(mp); 266 vfs_mountedfrom(mp, "tmpfs"); 267 268 return 0; 269 } 270 271 /* ARGSUSED2 */ 272 static int 273 tmpfs_unmount(struct mount *mp, int mntflags) 274 { 275 struct tmpfs_mount *tmp; 276 struct tmpfs_node *node; 277 int error, flags; 278 279 flags = (mntflags & MNT_FORCE) != 0 ? FORCECLOSE : 0; 280 tmp = VFS_TO_TMPFS(mp); 281 282 /* Stop writers */ 283 error = vfs_write_suspend_umnt(mp); 284 if (error != 0) 285 return (error); 286 /* 287 * At this point, nodes cannot be destroyed by any other 288 * thread because write suspension is started. 289 */ 290 291 for (;;) { 292 error = vflush(mp, 0, flags, curthread); 293 if (error != 0) { 294 vfs_write_resume(mp, VR_START_WRITE); 295 return (error); 296 } 297 MNT_ILOCK(mp); 298 if (mp->mnt_nvnodelistsize == 0) { 299 MNT_IUNLOCK(mp); 300 break; 301 } 302 MNT_IUNLOCK(mp); 303 if ((mntflags & MNT_FORCE) == 0) { 304 vfs_write_resume(mp, VR_START_WRITE); 305 return (EBUSY); 306 } 307 } 308 309 TMPFS_LOCK(tmp); 310 while ((node = LIST_FIRST(&tmp->tm_nodes_used)) != NULL) { 311 TMPFS_NODE_LOCK(node); 312 if (node->tn_type == VDIR) 313 tmpfs_dir_destroy(tmp, node); 314 if (tmpfs_free_node_locked(tmp, node, true)) 315 TMPFS_LOCK(tmp); 316 else 317 TMPFS_NODE_UNLOCK(node); 318 } 319 320 mp->mnt_data = NULL; 321 tmpfs_free_tmp(tmp); 322 vfs_write_resume(mp, VR_START_WRITE); 323 324 MNT_ILOCK(mp); 325 mp->mnt_flag &= ~MNT_LOCAL; 326 MNT_IUNLOCK(mp); 327 328 return (0); 329 } 330 331 void 332 tmpfs_free_tmp(struct tmpfs_mount *tmp) 333 { 334 335 MPASS(tmp->tm_refcount > 0); 336 tmp->tm_refcount--; 337 if (tmp->tm_refcount > 0) { 338 TMPFS_UNLOCK(tmp); 339 return; 340 } 341 TMPFS_UNLOCK(tmp); 342 343 uma_zdestroy(tmp->tm_dirent_pool); 344 uma_zdestroy(tmp->tm_node_pool); 345 346 mtx_destroy(&tmp->tm_allnode_lock); 347 MPASS(tmp->tm_pages_used == 0); 348 MPASS(tmp->tm_nodes_inuse == 0); 349 350 free(tmp, M_TMPFSMNT); 351 } 352 353 static int 354 tmpfs_root(struct mount *mp, int flags, struct vnode **vpp) 355 { 356 int error; 357 358 error = tmpfs_alloc_vp(mp, VFS_TO_TMPFS(mp)->tm_root, flags, vpp); 359 if (error == 0) 360 (*vpp)->v_vflag |= VV_ROOT; 361 return (error); 362 } 363 364 static int 365 tmpfs_fhtovp(struct mount *mp, struct fid *fhp, int flags, 366 struct vnode **vpp) 367 { 368 struct tmpfs_fid *tfhp; 369 struct tmpfs_mount *tmp; 370 struct tmpfs_node *node; 371 int error; 372 373 tmp = VFS_TO_TMPFS(mp); 374 375 tfhp = (struct tmpfs_fid *)fhp; 376 if (tfhp->tf_len != sizeof(struct tmpfs_fid)) 377 return (EINVAL); 378 379 if (tfhp->tf_id >= tmp->tm_nodes_max) 380 return (EINVAL); 381 382 TMPFS_LOCK(tmp); 383 LIST_FOREACH(node, &tmp->tm_nodes_used, tn_entries) { 384 if (node->tn_id == tfhp->tf_id && 385 node->tn_gen == tfhp->tf_gen) { 386 tmpfs_ref_node(node); 387 break; 388 } 389 } 390 TMPFS_UNLOCK(tmp); 391 392 if (node != NULL) { 393 error = tmpfs_alloc_vp(mp, node, LK_EXCLUSIVE, vpp); 394 tmpfs_free_node(tmp, node); 395 } else 396 error = EINVAL; 397 return (error); 398 } 399 400 /* ARGSUSED2 */ 401 static int 402 tmpfs_statfs(struct mount *mp, struct statfs *sbp) 403 { 404 struct tmpfs_mount *tmp; 405 size_t used; 406 407 tmp = VFS_TO_TMPFS(mp); 408 409 sbp->f_iosize = PAGE_SIZE; 410 sbp->f_bsize = PAGE_SIZE; 411 412 used = tmpfs_pages_used(tmp); 413 if (tmp->tm_pages_max != ULONG_MAX) 414 sbp->f_blocks = tmp->tm_pages_max; 415 else 416 sbp->f_blocks = used + tmpfs_mem_avail(); 417 if (sbp->f_blocks <= used) 418 sbp->f_bavail = 0; 419 else 420 sbp->f_bavail = sbp->f_blocks - used; 421 sbp->f_bfree = sbp->f_bavail; 422 used = tmp->tm_nodes_inuse; 423 sbp->f_files = tmp->tm_nodes_max; 424 if (sbp->f_files <= used) 425 sbp->f_ffree = 0; 426 else 427 sbp->f_ffree = sbp->f_files - used; 428 /* sbp->f_owner = tmp->tn_uid; */ 429 430 return 0; 431 } 432 433 static int 434 tmpfs_sync(struct mount *mp, int waitfor) 435 { 436 struct vnode *vp, *mvp; 437 struct vm_object *obj; 438 439 if (waitfor == MNT_SUSPEND) { 440 MNT_ILOCK(mp); 441 mp->mnt_kern_flag |= MNTK_SUSPEND2 | MNTK_SUSPENDED; 442 MNT_IUNLOCK(mp); 443 } else if (waitfor == MNT_LAZY) { 444 /* 445 * Handle lazy updates of mtime from writes to mmaped 446 * regions. Use MNT_VNODE_FOREACH_ALL instead of 447 * MNT_VNODE_FOREACH_ACTIVE, since unmap of the 448 * tmpfs-backed vnode does not call vinactive(), due 449 * to vm object type is OBJT_SWAP. 450 */ 451 MNT_VNODE_FOREACH_ALL(vp, mp, mvp) { 452 if (vp->v_type != VREG) { 453 VI_UNLOCK(vp); 454 continue; 455 } 456 obj = vp->v_object; 457 KASSERT((obj->flags & (OBJ_TMPFS_NODE | OBJ_TMPFS)) == 458 (OBJ_TMPFS_NODE | OBJ_TMPFS), ("non-tmpfs obj")); 459 460 /* 461 * Unlocked read, avoid taking vnode lock if 462 * not needed. Lost update will be handled on 463 * the next call. 464 */ 465 if ((obj->flags & OBJ_TMPFS_DIRTY) == 0) { 466 VI_UNLOCK(vp); 467 continue; 468 } 469 if (vget(vp, LK_EXCLUSIVE | LK_RETRY | LK_INTERLOCK, 470 curthread) != 0) 471 continue; 472 tmpfs_check_mtime(vp); 473 vput(vp); 474 } 475 } 476 return (0); 477 } 478 479 /* 480 * The presence of a susp_clean method tells the VFS to track writes. 481 */ 482 static void 483 tmpfs_susp_clean(struct mount *mp __unused) 484 { 485 } 486 487 /* 488 * tmpfs vfs operations. 489 */ 490 491 struct vfsops tmpfs_vfsops = { 492 .vfs_mount = tmpfs_mount, 493 .vfs_unmount = tmpfs_unmount, 494 .vfs_root = tmpfs_root, 495 .vfs_statfs = tmpfs_statfs, 496 .vfs_fhtovp = tmpfs_fhtovp, 497 .vfs_sync = tmpfs_sync, 498 .vfs_susp_clean = tmpfs_susp_clean, 499 }; 500 VFS_SET(tmpfs_vfsops, tmpfs, VFCF_JAIL); 501