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 * Copyright (c) 2005 The NetBSD Foundation, Inc. 5 * All rights reserved. 6 * 7 * This code is derived from software contributed to The NetBSD Foundation 8 * by Julio M. Merino Vidal, developed as part of Google's Summer of Code 9 * 2005 program. 10 * 11 * Redistribution and use in source and binary forms, with or without 12 * modification, are permitted provided that the following conditions 13 * are met: 14 * 1. Redistributions of source code must retain the above copyright 15 * notice, this list of conditions and the following disclaimer. 16 * 2. Redistributions in binary form must reproduce the above copyright 17 * notice, this list of conditions and the following disclaimer in the 18 * documentation and/or other materials provided with the distribution. 19 * 20 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 21 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 22 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 23 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 24 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 25 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 26 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 27 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 28 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 29 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 30 * POSSIBILITY OF SUCH DAMAGE. 31 */ 32 33 /* 34 * Efficient memory file system. 35 * 36 * tmpfs is a file system that uses NetBSD's virtual memory sub-system 37 * (the well-known UVM) to store file data and metadata in an efficient 38 * way. This means that it does not follow the structure of an on-disk 39 * file system because it simply does not need to. Instead, it uses 40 * memory-specific data structures and algorithms to automatically 41 * allocate and release resources. 42 */ 43 #include <sys/cdefs.h> 44 __FBSDID("$FreeBSD: releng/8.0/sys/fs/tmpfs/tmpfs_vfsops.c 191990 2009-05-11 15:33:26Z attilio $"); 45 46 #include <sys/param.h> 47 #include <sys/limits.h> 48 #include <sys/lock.h> 49 #include <sys/mutex.h> 50 #include <sys/kernel.h> 51 #include <sys/stat.h> 52 #include <sys/systm.h> 53 #include <sys/sysctl.h> 54 55 #include <vm/vm.h> 56 #include <vm/vm_object.h> 57 #include <vm/vm_param.h> 58 59 #include <fs/tmpfs/tmpfs.h> 60 61 /* 62 * Default permission for root node 63 */ 64 #define TMPFS_DEFAULT_ROOT_MODE (S_IRWXU|S_IRGRP|S_IXGRP|S_IROTH|S_IXOTH) 65 66 MALLOC_DEFINE(M_TMPFSMNT, "tmpfs mount", "tmpfs mount structures"); 67 MALLOC_DEFINE(M_TMPFSNAME, "tmpfs name", "tmpfs file names"); 68 69 /* --------------------------------------------------------------------- */ 70 71 static int tmpfs_mount(struct mount *); 72 static int tmpfs_unmount(struct mount *, int); 73 static int tmpfs_root(struct mount *, int flags, struct vnode **); 74 static int tmpfs_fhtovp(struct mount *, struct fid *, struct vnode **); 75 static int tmpfs_statfs(struct mount *, struct statfs *); 76 77 /* --------------------------------------------------------------------- */ 78 79 static const char *tmpfs_opts[] = { 80 "from", "size", "inodes", "uid", "gid", "mode", "export", 81 NULL 82 }; 83 84 /* --------------------------------------------------------------------- */ 85 86 #define SWI_MAXMIB 3 87 88 static u_int 89 get_swpgtotal(void) 90 { 91 struct xswdev xsd; 92 char *sname = "vm.swap_info"; 93 int soid[SWI_MAXMIB], oid[2]; 94 u_int unswdev, total, dmmax, nswapdev; 95 size_t mibi, len; 96 97 total = 0; 98 99 len = sizeof(dmmax); 100 if (kernel_sysctlbyname(curthread, "vm.dmmax", &dmmax, &len, 101 NULL, 0, NULL, 0) != 0) 102 return total; 103 104 len = sizeof(nswapdev); 105 if (kernel_sysctlbyname(curthread, "vm.nswapdev", 106 &nswapdev, &len, 107 NULL, 0, NULL, 0) != 0) 108 return total; 109 110 mibi = (SWI_MAXMIB - 1) * sizeof(int); 111 oid[0] = 0; 112 oid[1] = 3; 113 114 if (kernel_sysctl(curthread, oid, 2, 115 soid, &mibi, (void *)sname, strlen(sname), 116 NULL, 0) != 0) 117 return total; 118 119 mibi = (SWI_MAXMIB - 1); 120 for (unswdev = 0; unswdev < nswapdev; ++unswdev) { 121 soid[mibi] = unswdev; 122 len = sizeof(struct xswdev); 123 if (kernel_sysctl(curthread, 124 soid, mibi + 1, &xsd, &len, NULL, 0, 125 NULL, 0) != 0) 126 return total; 127 if (len == sizeof(struct xswdev)) 128 total += (xsd.xsw_nblks - dmmax); 129 } 130 131 /* Not Reached */ 132 return total; 133 } 134 135 /* --------------------------------------------------------------------- */ 136 static int 137 tmpfs_node_ctor(void *mem, int size, void *arg, int flags) 138 { 139 struct tmpfs_node *node = (struct tmpfs_node *)mem; 140 141 node->tn_gen++; 142 node->tn_size = 0; 143 node->tn_status = 0; 144 node->tn_flags = 0; 145 node->tn_links = 0; 146 node->tn_vnode = NULL; 147 node->tn_vpstate = 0; 148 149 return (0); 150 } 151 152 static void 153 tmpfs_node_dtor(void *mem, int size, void *arg) 154 { 155 struct tmpfs_node *node = (struct tmpfs_node *)mem; 156 node->tn_type = VNON; 157 } 158 159 static int 160 tmpfs_node_init(void *mem, int size, int flags) 161 { 162 struct tmpfs_node *node = (struct tmpfs_node *)mem; 163 node->tn_id = 0; 164 165 mtx_init(&node->tn_interlock, "tmpfs node interlock", NULL, MTX_DEF); 166 node->tn_gen = arc4random(); 167 168 return (0); 169 } 170 171 static void 172 tmpfs_node_fini(void *mem, int size) 173 { 174 struct tmpfs_node *node = (struct tmpfs_node *)mem; 175 176 mtx_destroy(&node->tn_interlock); 177 } 178 179 static int 180 tmpfs_mount(struct mount *mp) 181 { 182 struct tmpfs_mount *tmp; 183 struct tmpfs_node *root; 184 size_t pages, mem_size; 185 ino_t nodes; 186 int error; 187 /* Size counters. */ 188 ino_t nodes_max; 189 size_t size_max; 190 191 /* Root node attributes. */ 192 uid_t root_uid; 193 gid_t root_gid; 194 mode_t root_mode; 195 196 struct vattr va; 197 198 if (vfs_filteropt(mp->mnt_optnew, tmpfs_opts)) 199 return (EINVAL); 200 201 if (mp->mnt_flag & MNT_UPDATE) { 202 /* XXX: There is no support yet to update file system 203 * settings. Should be added. */ 204 205 return EOPNOTSUPP; 206 } 207 208 printf("WARNING: TMPFS is considered to be a highly experimental " 209 "feature in FreeBSD.\n"); 210 211 vn_lock(mp->mnt_vnodecovered, LK_SHARED | LK_RETRY); 212 error = VOP_GETATTR(mp->mnt_vnodecovered, &va, mp->mnt_cred); 213 VOP_UNLOCK(mp->mnt_vnodecovered, 0); 214 if (error) 215 return (error); 216 217 if (mp->mnt_cred->cr_ruid != 0 || 218 vfs_scanopt(mp->mnt_optnew, "gid", "%d", &root_gid) != 1) 219 root_gid = va.va_gid; 220 if (mp->mnt_cred->cr_ruid != 0 || 221 vfs_scanopt(mp->mnt_optnew, "uid", "%d", &root_uid) != 1) 222 root_uid = va.va_uid; 223 if (mp->mnt_cred->cr_ruid != 0 || 224 vfs_scanopt(mp->mnt_optnew, "mode", "%ho", &root_mode) != 1) 225 root_mode = va.va_mode; 226 if (vfs_scanopt(mp->mnt_optnew, "inodes", "%d", &nodes_max) != 1) 227 nodes_max = 0; 228 if (vfs_scanopt(mp->mnt_optnew, "size", "%qu", &size_max) != 1) 229 size_max = 0; 230 231 /* Do not allow mounts if we do not have enough memory to preserve 232 * the minimum reserved pages. */ 233 mem_size = cnt.v_free_count + cnt.v_inactive_count + get_swpgtotal(); 234 mem_size -= mem_size > cnt.v_wire_count ? cnt.v_wire_count : mem_size; 235 if (mem_size < TMPFS_PAGES_RESERVED) 236 return ENOSPC; 237 238 /* Get the maximum number of memory pages this file system is 239 * allowed to use, based on the maximum size the user passed in 240 * the mount structure. A value of zero is treated as if the 241 * maximum available space was requested. */ 242 if (size_max < PAGE_SIZE || size_max >= SIZE_MAX) 243 pages = SIZE_MAX; 244 else 245 pages = howmany(size_max, PAGE_SIZE); 246 MPASS(pages > 0); 247 248 if (nodes_max <= 3) 249 nodes = 3 + pages * PAGE_SIZE / 1024; 250 else 251 nodes = nodes_max; 252 MPASS(nodes >= 3); 253 254 /* Allocate the tmpfs mount structure and fill it. */ 255 tmp = (struct tmpfs_mount *)malloc(sizeof(struct tmpfs_mount), 256 M_TMPFSMNT, M_WAITOK | M_ZERO); 257 258 mtx_init(&tmp->allnode_lock, "tmpfs allnode lock", NULL, MTX_DEF); 259 tmp->tm_nodes_max = nodes; 260 tmp->tm_nodes_inuse = 0; 261 tmp->tm_maxfilesize = (u_int64_t)(cnt.v_page_count + get_swpgtotal()) * PAGE_SIZE; 262 LIST_INIT(&tmp->tm_nodes_used); 263 264 tmp->tm_pages_max = pages; 265 tmp->tm_pages_used = 0; 266 tmp->tm_ino_unr = new_unrhdr(2, INT_MAX, &tmp->allnode_lock); 267 tmp->tm_dirent_pool = uma_zcreate("TMPFS dirent", 268 sizeof(struct tmpfs_dirent), 269 NULL, NULL, NULL, NULL, 270 UMA_ALIGN_PTR, 0); 271 tmp->tm_node_pool = uma_zcreate("TMPFS node", 272 sizeof(struct tmpfs_node), 273 tmpfs_node_ctor, tmpfs_node_dtor, 274 tmpfs_node_init, tmpfs_node_fini, 275 UMA_ALIGN_PTR, 0); 276 277 /* Allocate the root node. */ 278 error = tmpfs_alloc_node(tmp, VDIR, root_uid, 279 root_gid, root_mode & ALLPERMS, NULL, NULL, 280 VNOVAL, &root); 281 282 if (error != 0 || root == NULL) { 283 uma_zdestroy(tmp->tm_node_pool); 284 uma_zdestroy(tmp->tm_dirent_pool); 285 delete_unrhdr(tmp->tm_ino_unr); 286 free(tmp, M_TMPFSMNT); 287 return error; 288 } 289 KASSERT(root->tn_id == 2, ("tmpfs root with invalid ino: %d", root->tn_id)); 290 tmp->tm_root = root; 291 292 MNT_ILOCK(mp); 293 mp->mnt_flag |= MNT_LOCAL; 294 mp->mnt_kern_flag |= MNTK_MPSAFE; 295 MNT_IUNLOCK(mp); 296 297 mp->mnt_data = tmp; 298 mp->mnt_stat.f_namemax = MAXNAMLEN; 299 vfs_getnewfsid(mp); 300 vfs_mountedfrom(mp, "tmpfs"); 301 302 return 0; 303 } 304 305 /* --------------------------------------------------------------------- */ 306 307 /* ARGSUSED2 */ 308 static int 309 tmpfs_unmount(struct mount *mp, int mntflags) 310 { 311 int error; 312 int flags = 0; 313 struct tmpfs_mount *tmp; 314 struct tmpfs_node *node; 315 316 /* Handle forced unmounts. */ 317 if (mntflags & MNT_FORCE) 318 flags |= FORCECLOSE; 319 320 /* Finalize all pending I/O. */ 321 error = vflush(mp, 0, flags, curthread); 322 if (error != 0) 323 return error; 324 325 tmp = VFS_TO_TMPFS(mp); 326 327 /* Free all associated data. The loop iterates over the linked list 328 * we have containing all used nodes. For each of them that is 329 * a directory, we free all its directory entries. Note that after 330 * freeing a node, it will automatically go to the available list, 331 * so we will later have to iterate over it to release its items. */ 332 node = LIST_FIRST(&tmp->tm_nodes_used); 333 while (node != NULL) { 334 struct tmpfs_node *next; 335 336 if (node->tn_type == VDIR) { 337 struct tmpfs_dirent *de; 338 339 de = TAILQ_FIRST(&node->tn_dir.tn_dirhead); 340 while (de != NULL) { 341 struct tmpfs_dirent *nde; 342 343 nde = TAILQ_NEXT(de, td_entries); 344 tmpfs_free_dirent(tmp, de, FALSE); 345 de = nde; 346 node->tn_size -= sizeof(struct tmpfs_dirent); 347 } 348 } 349 350 next = LIST_NEXT(node, tn_entries); 351 tmpfs_free_node(tmp, node); 352 node = next; 353 } 354 355 uma_zdestroy(tmp->tm_dirent_pool); 356 uma_zdestroy(tmp->tm_node_pool); 357 delete_unrhdr(tmp->tm_ino_unr); 358 359 mtx_destroy(&tmp->allnode_lock); 360 MPASS(tmp->tm_pages_used == 0); 361 MPASS(tmp->tm_nodes_inuse == 0); 362 363 /* Throw away the tmpfs_mount structure. */ 364 free(mp->mnt_data, M_TMPFSMNT); 365 mp->mnt_data = NULL; 366 367 MNT_ILOCK(mp); 368 mp->mnt_flag &= ~MNT_LOCAL; 369 MNT_IUNLOCK(mp); 370 return 0; 371 } 372 373 /* --------------------------------------------------------------------- */ 374 375 static int 376 tmpfs_root(struct mount *mp, int flags, struct vnode **vpp) 377 { 378 int error; 379 error = tmpfs_alloc_vp(mp, VFS_TO_TMPFS(mp)->tm_root, flags, vpp); 380 381 if (!error) 382 (*vpp)->v_vflag |= VV_ROOT; 383 384 return error; 385 } 386 387 /* --------------------------------------------------------------------- */ 388 389 static int 390 tmpfs_fhtovp(struct mount *mp, struct fid *fhp, struct vnode **vpp) 391 { 392 boolean_t found; 393 struct tmpfs_fid *tfhp; 394 struct tmpfs_mount *tmp; 395 struct tmpfs_node *node; 396 397 tmp = VFS_TO_TMPFS(mp); 398 399 tfhp = (struct tmpfs_fid *)fhp; 400 if (tfhp->tf_len != sizeof(struct tmpfs_fid)) 401 return EINVAL; 402 403 if (tfhp->tf_id >= tmp->tm_nodes_max) 404 return EINVAL; 405 406 found = FALSE; 407 408 TMPFS_LOCK(tmp); 409 LIST_FOREACH(node, &tmp->tm_nodes_used, tn_entries) { 410 if (node->tn_id == tfhp->tf_id && 411 node->tn_gen == tfhp->tf_gen) { 412 found = TRUE; 413 break; 414 } 415 } 416 TMPFS_UNLOCK(tmp); 417 418 if (found) 419 return (tmpfs_alloc_vp(mp, node, LK_EXCLUSIVE, vpp)); 420 421 return (EINVAL); 422 } 423 424 /* --------------------------------------------------------------------- */ 425 426 /* ARGSUSED2 */ 427 static int 428 tmpfs_statfs(struct mount *mp, struct statfs *sbp) 429 { 430 fsfilcnt_t freenodes; 431 struct tmpfs_mount *tmp; 432 433 tmp = VFS_TO_TMPFS(mp); 434 435 sbp->f_iosize = PAGE_SIZE; 436 sbp->f_bsize = PAGE_SIZE; 437 438 sbp->f_blocks = TMPFS_PAGES_MAX(tmp); 439 sbp->f_bavail = sbp->f_bfree = TMPFS_PAGES_AVAIL(tmp); 440 441 freenodes = MIN(tmp->tm_nodes_max - tmp->tm_nodes_inuse, 442 TMPFS_PAGES_AVAIL(tmp) * PAGE_SIZE / sizeof(struct tmpfs_node)); 443 444 sbp->f_files = freenodes + tmp->tm_nodes_inuse; 445 sbp->f_ffree = freenodes; 446 /* sbp->f_owner = tmp->tn_uid; */ 447 448 return 0; 449 } 450 451 /* --------------------------------------------------------------------- */ 452 453 /* 454 * tmpfs vfs operations. 455 */ 456 457 struct vfsops tmpfs_vfsops = { 458 .vfs_mount = tmpfs_mount, 459 .vfs_unmount = tmpfs_unmount, 460 .vfs_root = tmpfs_root, 461 .vfs_statfs = tmpfs_statfs, 462 .vfs_fhtovp = tmpfs_fhtovp, 463 }; 464 VFS_SET(tmpfs_vfsops, tmpfs, 0);
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