Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)
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FreeBSD/Linux Kernel Cross Reference
sys/fs/tmpfs/tmpfs_vfsops.c
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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: releng/12.0/sys/fs/tmpfs/tmpfs_vfsops.c 341085 2018-11-27 17:58:25Z markj $"); 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 tmp->tm_ino_unr = new_unrhdr(2, INT_MAX, &tmp->tm_allnode_lock); 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 delete_unrhdr(tmp->tm_ino_unr); 252 free(tmp, M_TMPFSMNT); 253 return (error); 254 } 255 KASSERT(root->tn_id == 2, 256 ("tmpfs root with invalid ino: %ju", (uintmax_t)root->tn_id)); 257 tmp->tm_root = root; 258 259 MNT_ILOCK(mp); 260 mp->mnt_flag |= MNT_LOCAL; 261 mp->mnt_kern_flag |= MNTK_LOOKUP_SHARED | MNTK_EXTENDED_SHARED; 262 MNT_IUNLOCK(mp); 263 264 mp->mnt_data = tmp; 265 mp->mnt_stat.f_namemax = MAXNAMLEN; 266 vfs_getnewfsid(mp); 267 vfs_mountedfrom(mp, "tmpfs"); 268 269 return 0; 270 } 271 272 /* ARGSUSED2 */ 273 static int 274 tmpfs_unmount(struct mount *mp, int mntflags) 275 { 276 struct tmpfs_mount *tmp; 277 struct tmpfs_node *node; 278 int error, flags; 279 280 flags = (mntflags & MNT_FORCE) != 0 ? FORCECLOSE : 0; 281 tmp = VFS_TO_TMPFS(mp); 282 283 /* Stop writers */ 284 error = vfs_write_suspend_umnt(mp); 285 if (error != 0) 286 return (error); 287 /* 288 * At this point, nodes cannot be destroyed by any other 289 * thread because write suspension is started. 290 */ 291 292 for (;;) { 293 error = vflush(mp, 0, flags, curthread); 294 if (error != 0) { 295 vfs_write_resume(mp, VR_START_WRITE); 296 return (error); 297 } 298 MNT_ILOCK(mp); 299 if (mp->mnt_nvnodelistsize == 0) { 300 MNT_IUNLOCK(mp); 301 break; 302 } 303 MNT_IUNLOCK(mp); 304 if ((mntflags & MNT_FORCE) == 0) { 305 vfs_write_resume(mp, VR_START_WRITE); 306 return (EBUSY); 307 } 308 } 309 310 TMPFS_LOCK(tmp); 311 while ((node = LIST_FIRST(&tmp->tm_nodes_used)) != NULL) { 312 TMPFS_NODE_LOCK(node); 313 if (node->tn_type == VDIR) 314 tmpfs_dir_destroy(tmp, node); 315 if (tmpfs_free_node_locked(tmp, node, true)) 316 TMPFS_LOCK(tmp); 317 else 318 TMPFS_NODE_UNLOCK(node); 319 } 320 321 mp->mnt_data = NULL; 322 tmpfs_free_tmp(tmp); 323 vfs_write_resume(mp, VR_START_WRITE); 324 325 MNT_ILOCK(mp); 326 mp->mnt_flag &= ~MNT_LOCAL; 327 MNT_IUNLOCK(mp); 328 329 return (0); 330 } 331 332 void 333 tmpfs_free_tmp(struct tmpfs_mount *tmp) 334 { 335 336 MPASS(tmp->tm_refcount > 0); 337 tmp->tm_refcount--; 338 if (tmp->tm_refcount > 0) { 339 TMPFS_UNLOCK(tmp); 340 return; 341 } 342 TMPFS_UNLOCK(tmp); 343 344 uma_zdestroy(tmp->tm_dirent_pool); 345 uma_zdestroy(tmp->tm_node_pool); 346 clear_unrhdr(tmp->tm_ino_unr); 347 delete_unrhdr(tmp->tm_ino_unr); 348 349 mtx_destroy(&tmp->tm_allnode_lock); 350 MPASS(tmp->tm_pages_used == 0); 351 MPASS(tmp->tm_nodes_inuse == 0); 352 353 free(tmp, M_TMPFSMNT); 354 } 355 356 static int 357 tmpfs_root(struct mount *mp, int flags, struct vnode **vpp) 358 { 359 int error; 360 361 error = tmpfs_alloc_vp(mp, VFS_TO_TMPFS(mp)->tm_root, flags, vpp); 362 if (error == 0) 363 (*vpp)->v_vflag |= VV_ROOT; 364 return (error); 365 } 366 367 static int 368 tmpfs_fhtovp(struct mount *mp, struct fid *fhp, int flags, 369 struct vnode **vpp) 370 { 371 struct tmpfs_fid *tfhp; 372 struct tmpfs_mount *tmp; 373 struct tmpfs_node *node; 374 int error; 375 376 tmp = VFS_TO_TMPFS(mp); 377 378 tfhp = (struct tmpfs_fid *)fhp; 379 if (tfhp->tf_len != sizeof(struct tmpfs_fid)) 380 return (EINVAL); 381 382 if (tfhp->tf_id >= tmp->tm_nodes_max) 383 return (EINVAL); 384 385 TMPFS_LOCK(tmp); 386 LIST_FOREACH(node, &tmp->tm_nodes_used, tn_entries) { 387 if (node->tn_id == tfhp->tf_id && 388 node->tn_gen == tfhp->tf_gen) { 389 tmpfs_ref_node(node); 390 break; 391 } 392 } 393 TMPFS_UNLOCK(tmp); 394 395 if (node != NULL) { 396 error = tmpfs_alloc_vp(mp, node, LK_EXCLUSIVE, vpp); 397 tmpfs_free_node(tmp, node); 398 } else 399 error = EINVAL; 400 return (error); 401 } 402 403 /* ARGSUSED2 */ 404 static int 405 tmpfs_statfs(struct mount *mp, struct statfs *sbp) 406 { 407 struct tmpfs_mount *tmp; 408 size_t used; 409 410 tmp = VFS_TO_TMPFS(mp); 411 412 sbp->f_iosize = PAGE_SIZE; 413 sbp->f_bsize = PAGE_SIZE; 414 415 used = tmpfs_pages_used(tmp); 416 if (tmp->tm_pages_max != ULONG_MAX) 417 sbp->f_blocks = tmp->tm_pages_max; 418 else 419 sbp->f_blocks = used + tmpfs_mem_avail(); 420 if (sbp->f_blocks <= used) 421 sbp->f_bavail = 0; 422 else 423 sbp->f_bavail = sbp->f_blocks - used; 424 sbp->f_bfree = sbp->f_bavail; 425 used = tmp->tm_nodes_inuse; 426 sbp->f_files = tmp->tm_nodes_max; 427 if (sbp->f_files <= used) 428 sbp->f_ffree = 0; 429 else 430 sbp->f_ffree = sbp->f_files - used; 431 /* sbp->f_owner = tmp->tn_uid; */ 432 433 return 0; 434 } 435 436 static int 437 tmpfs_sync(struct mount *mp, int waitfor) 438 { 439 struct vnode *vp, *mvp; 440 struct vm_object *obj; 441 442 if (waitfor == MNT_SUSPEND) { 443 MNT_ILOCK(mp); 444 mp->mnt_kern_flag |= MNTK_SUSPEND2 | MNTK_SUSPENDED; 445 MNT_IUNLOCK(mp); 446 } else if (waitfor == MNT_LAZY) { 447 /* 448 * Handle lazy updates of mtime from writes to mmaped 449 * regions. Use MNT_VNODE_FOREACH_ALL instead of 450 * MNT_VNODE_FOREACH_ACTIVE, since unmap of the 451 * tmpfs-backed vnode does not call vinactive(), due 452 * to vm object type is OBJT_SWAP. 453 */ 454 MNT_VNODE_FOREACH_ALL(vp, mp, mvp) { 455 if (vp->v_type != VREG) { 456 VI_UNLOCK(vp); 457 continue; 458 } 459 obj = vp->v_object; 460 KASSERT((obj->flags & (OBJ_TMPFS_NODE | OBJ_TMPFS)) == 461 (OBJ_TMPFS_NODE | OBJ_TMPFS), ("non-tmpfs obj")); 462 463 /* 464 * Unlocked read, avoid taking vnode lock if 465 * not needed. Lost update will be handled on 466 * the next call. 467 */ 468 if ((obj->flags & OBJ_TMPFS_DIRTY) == 0) { 469 VI_UNLOCK(vp); 470 continue; 471 } 472 if (vget(vp, LK_EXCLUSIVE | LK_RETRY | LK_INTERLOCK, 473 curthread) != 0) 474 continue; 475 tmpfs_check_mtime(vp); 476 vput(vp); 477 } 478 } 479 return (0); 480 } 481 482 /* 483 * The presence of a susp_clean method tells the VFS to track writes. 484 */ 485 static void 486 tmpfs_susp_clean(struct mount *mp __unused) 487 { 488 } 489 490 /* 491 * tmpfs vfs operations. 492 */ 493 494 struct vfsops tmpfs_vfsops = { 495 .vfs_mount = tmpfs_mount, 496 .vfs_unmount = tmpfs_unmount, 497 .vfs_root = tmpfs_root, 498 .vfs_statfs = tmpfs_statfs, 499 .vfs_fhtovp = tmpfs_fhtovp, 500 .vfs_sync = tmpfs_sync, 501 .vfs_susp_clean = tmpfs_susp_clean, 502 }; 503 VFS_SET(tmpfs_vfsops, tmpfs, VFCF_JAIL);
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