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("$FreeBSD$"); 45 46 #include <sys/param.h> 47 #include <sys/limits.h> 48 #include <sys/lock.h> 49 #include <sys/mutex.h> 50 #include <sys/proc.h> 51 #include <sys/jail.h> 52 #include <sys/kernel.h> 53 #include <sys/stat.h> 54 #include <sys/systm.h> 55 #include <sys/sysctl.h> 56 57 #include <vm/vm.h> 58 #include <vm/vm_object.h> 59 #include <vm/vm_param.h> 60 61 #include <fs/tmpfs/tmpfs.h> 62 63 /* 64 * Default permission for root node 65 */ 66 #define TMPFS_DEFAULT_ROOT_MODE (S_IRWXU|S_IRGRP|S_IXGRP|S_IROTH|S_IXOTH) 67 68 MALLOC_DEFINE(M_TMPFSMNT, "tmpfs mount", "tmpfs mount structures"); 69 MALLOC_DEFINE(M_TMPFSNAME, "tmpfs name", "tmpfs file names"); 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 *, int, 75 struct vnode **); 76 static int tmpfs_statfs(struct mount *, struct statfs *); 77 78 static const char *tmpfs_opts[] = { 79 "from", "size", "maxfilesize", "inodes", "uid", "gid", "mode", "export", 80 "union", NULL 81 }; 82 83 static const char *tmpfs_updateopts[] = { 84 "from", "export", NULL 85 }; 86 87 static int 88 tmpfs_node_ctor(void *mem, int size, void *arg, int flags) 89 { 90 struct tmpfs_node *node = (struct tmpfs_node *)mem; 91 92 node->tn_gen++; 93 node->tn_size = 0; 94 node->tn_status = 0; 95 node->tn_flags = 0; 96 node->tn_links = 0; 97 node->tn_vnode = NULL; 98 node->tn_vpstate = 0; 99 100 return (0); 101 } 102 103 static void 104 tmpfs_node_dtor(void *mem, int size, void *arg) 105 { 106 struct tmpfs_node *node = (struct tmpfs_node *)mem; 107 node->tn_type = VNON; 108 } 109 110 static int 111 tmpfs_node_init(void *mem, int size, int flags) 112 { 113 struct tmpfs_node *node = (struct tmpfs_node *)mem; 114 node->tn_id = 0; 115 116 mtx_init(&node->tn_interlock, "tmpfs node interlock", NULL, MTX_DEF); 117 node->tn_gen = arc4random(); 118 119 return (0); 120 } 121 122 static void 123 tmpfs_node_fini(void *mem, int size) 124 { 125 struct tmpfs_node *node = (struct tmpfs_node *)mem; 126 127 mtx_destroy(&node->tn_interlock); 128 } 129 130 static int 131 tmpfs_mount(struct mount *mp) 132 { 133 const size_t nodes_per_page = howmany(PAGE_SIZE, 134 sizeof(struct tmpfs_dirent) + sizeof(struct tmpfs_node)); 135 struct tmpfs_mount *tmp; 136 struct tmpfs_node *root; 137 struct thread *td = curthread; 138 int error; 139 /* Size counters. */ 140 u_quad_t pages; 141 off_t nodes_max, size_max, maxfilesize; 142 143 /* Root node attributes. */ 144 uid_t root_uid; 145 gid_t root_gid; 146 mode_t root_mode; 147 148 struct vattr va; 149 150 if (!prison_allow(td->td_ucred, PR_ALLOW_MOUNT_TMPFS)) 151 return (EPERM); 152 153 if (vfs_filteropt(mp->mnt_optnew, tmpfs_opts)) 154 return (EINVAL); 155 156 if (mp->mnt_flag & MNT_UPDATE) { 157 /* Only support update mounts for certain options. */ 158 if (vfs_filteropt(mp->mnt_optnew, tmpfs_updateopts) != 0) 159 return (EOPNOTSUPP); 160 if (vfs_flagopt(mp->mnt_optnew, "ro", NULL, 0) != 161 ((struct tmpfs_mount *)mp->mnt_data)->tm_ronly) 162 return (EOPNOTSUPP); 163 return (0); 164 } 165 166 vn_lock(mp->mnt_vnodecovered, LK_SHARED | LK_RETRY); 167 error = VOP_GETATTR(mp->mnt_vnodecovered, &va, mp->mnt_cred); 168 VOP_UNLOCK(mp->mnt_vnodecovered, 0); 169 if (error) 170 return (error); 171 172 if (mp->mnt_cred->cr_ruid != 0 || 173 vfs_scanopt(mp->mnt_optnew, "gid", "%d", &root_gid) != 1) 174 root_gid = va.va_gid; 175 if (mp->mnt_cred->cr_ruid != 0 || 176 vfs_scanopt(mp->mnt_optnew, "uid", "%d", &root_uid) != 1) 177 root_uid = va.va_uid; 178 if (mp->mnt_cred->cr_ruid != 0 || 179 vfs_scanopt(mp->mnt_optnew, "mode", "%ho", &root_mode) != 1) 180 root_mode = va.va_mode; 181 if (vfs_getopt_size(mp->mnt_optnew, "inodes", &nodes_max) != 0) 182 nodes_max = 0; 183 if (vfs_getopt_size(mp->mnt_optnew, "size", &size_max) != 0) 184 size_max = 0; 185 if (vfs_getopt_size(mp->mnt_optnew, "maxfilesize", &maxfilesize) != 0) 186 maxfilesize = 0; 187 188 /* Do not allow mounts if we do not have enough memory to preserve 189 * the minimum reserved pages. */ 190 if (tmpfs_mem_avail() < TMPFS_PAGES_MINRESERVED) 191 return ENOSPC; 192 193 /* Get the maximum number of memory pages this file system is 194 * allowed to use, based on the maximum size the user passed in 195 * the mount structure. A value of zero is treated as if the 196 * maximum available space was requested. */ 197 if (size_max == 0 || size_max > OFF_MAX - PAGE_SIZE || 198 (SIZE_MAX < OFF_MAX && size_max / PAGE_SIZE >= SIZE_MAX)) 199 pages = SIZE_MAX; 200 else { 201 size_max = roundup(size_max, PAGE_SIZE); 202 pages = howmany(size_max, PAGE_SIZE); 203 } 204 MPASS(pages > 0); 205 206 if (nodes_max <= 3) { 207 if (pages < INT_MAX / nodes_per_page) 208 nodes_max = pages * nodes_per_page; 209 else 210 nodes_max = INT_MAX; 211 } 212 if (nodes_max > INT_MAX) 213 nodes_max = INT_MAX; 214 MPASS(nodes_max >= 3); 215 216 /* Allocate the tmpfs mount structure and fill it. */ 217 tmp = (struct tmpfs_mount *)malloc(sizeof(struct tmpfs_mount), 218 M_TMPFSMNT, M_WAITOK | M_ZERO); 219 220 mtx_init(&tmp->allnode_lock, "tmpfs allnode lock", NULL, MTX_DEF); 221 tmp->tm_nodes_max = nodes_max; 222 tmp->tm_nodes_inuse = 0; 223 tmp->tm_maxfilesize = maxfilesize > 0 ? maxfilesize : OFF_MAX; 224 LIST_INIT(&tmp->tm_nodes_used); 225 226 tmp->tm_pages_max = pages; 227 tmp->tm_pages_used = 0; 228 tmp->tm_ino_unr = new_unrhdr(2, INT_MAX, &tmp->allnode_lock); 229 tmp->tm_dirent_pool = uma_zcreate("TMPFS dirent", 230 sizeof(struct tmpfs_dirent), 231 NULL, NULL, NULL, NULL, 232 UMA_ALIGN_PTR, 0); 233 tmp->tm_node_pool = uma_zcreate("TMPFS node", 234 sizeof(struct tmpfs_node), 235 tmpfs_node_ctor, tmpfs_node_dtor, 236 tmpfs_node_init, tmpfs_node_fini, 237 UMA_ALIGN_PTR, 0); 238 tmp->tm_ronly = (mp->mnt_flag & MNT_RDONLY) != 0; 239 240 /* Allocate the root node. */ 241 error = tmpfs_alloc_node(mp, tmp, VDIR, root_uid, 242 root_gid, root_mode & ALLPERMS, NULL, NULL, 243 VNOVAL, &root); 244 245 if (error != 0 || root == NULL) { 246 uma_zdestroy(tmp->tm_node_pool); 247 uma_zdestroy(tmp->tm_dirent_pool); 248 delete_unrhdr(tmp->tm_ino_unr); 249 free(tmp, M_TMPFSMNT); 250 return error; 251 } 252 KASSERT(root->tn_id == 2, 253 ("tmpfs root with invalid ino: %ju", (uintmax_t)root->tn_id)); 254 tmp->tm_root = root; 255 256 MNT_ILOCK(mp); 257 mp->mnt_flag |= MNT_LOCAL; 258 mp->mnt_kern_flag |= MNTK_LOOKUP_SHARED | MNTK_SUSPENDABLE; 259 MNT_IUNLOCK(mp); 260 261 mp->mnt_data = tmp; 262 mp->mnt_stat.f_namemax = MAXNAMLEN; 263 vfs_getnewfsid(mp); 264 vfs_mountedfrom(mp, "tmpfs"); 265 266 return 0; 267 } 268 269 /* ARGSUSED2 */ 270 static int 271 tmpfs_unmount(struct mount *mp, int mntflags) 272 { 273 struct tmpfs_mount *tmp; 274 struct tmpfs_node *node; 275 int error, flags; 276 277 flags = (mntflags & MNT_FORCE) != 0 ? FORCECLOSE : 0; 278 tmp = VFS_TO_TMPFS(mp); 279 280 /* Stop writers */ 281 error = vfs_write_suspend_umnt(mp); 282 if (error != 0) 283 return (error); 284 /* 285 * At this point, nodes cannot be destroyed by any other 286 * thread because write suspension is started. 287 */ 288 289 for (;;) { 290 error = vflush(mp, 0, flags, curthread); 291 if (error != 0) { 292 vfs_write_resume(mp, VR_START_WRITE); 293 return (error); 294 } 295 MNT_ILOCK(mp); 296 if (mp->mnt_nvnodelistsize == 0) { 297 MNT_IUNLOCK(mp); 298 break; 299 } 300 MNT_IUNLOCK(mp); 301 if ((mntflags & MNT_FORCE) == 0) { 302 vfs_write_resume(mp, VR_START_WRITE); 303 return (EBUSY); 304 } 305 } 306 307 TMPFS_LOCK(tmp); 308 while ((node = LIST_FIRST(&tmp->tm_nodes_used)) != NULL) { 309 TMPFS_UNLOCK(tmp); 310 if (node->tn_type == VDIR) 311 tmpfs_dir_destroy(tmp, node); 312 tmpfs_free_node(tmp, node); 313 TMPFS_LOCK(tmp); 314 } 315 TMPFS_UNLOCK(tmp); 316 317 uma_zdestroy(tmp->tm_dirent_pool); 318 uma_zdestroy(tmp->tm_node_pool); 319 delete_unrhdr(tmp->tm_ino_unr); 320 321 mtx_destroy(&tmp->allnode_lock); 322 MPASS(tmp->tm_pages_used == 0); 323 MPASS(tmp->tm_nodes_inuse == 0); 324 325 /* Throw away the tmpfs_mount structure. */ 326 free(mp->mnt_data, M_TMPFSMNT); 327 mp->mnt_data = NULL; 328 vfs_write_resume(mp, VR_START_WRITE); 329 330 MNT_ILOCK(mp); 331 mp->mnt_flag &= ~MNT_LOCAL; 332 MNT_IUNLOCK(mp); 333 334 return (0); 335 } 336 337 static int 338 tmpfs_root(struct mount *mp, int flags, struct vnode **vpp) 339 { 340 int error; 341 error = tmpfs_alloc_vp(mp, VFS_TO_TMPFS(mp)->tm_root, flags, vpp); 342 343 if (!error) 344 (*vpp)->v_vflag |= VV_ROOT; 345 346 return error; 347 } 348 349 static int 350 tmpfs_fhtovp(struct mount *mp, struct fid *fhp, int flags, 351 struct vnode **vpp) 352 { 353 boolean_t found; 354 struct tmpfs_fid *tfhp; 355 struct tmpfs_mount *tmp; 356 struct tmpfs_node *node; 357 358 tmp = VFS_TO_TMPFS(mp); 359 360 tfhp = (struct tmpfs_fid *)fhp; 361 if (tfhp->tf_len != sizeof(struct tmpfs_fid)) 362 return EINVAL; 363 364 if (tfhp->tf_id >= tmp->tm_nodes_max) 365 return EINVAL; 366 367 found = FALSE; 368 369 TMPFS_LOCK(tmp); 370 LIST_FOREACH(node, &tmp->tm_nodes_used, tn_entries) { 371 if (node->tn_id == tfhp->tf_id && 372 node->tn_gen == tfhp->tf_gen) { 373 found = TRUE; 374 break; 375 } 376 } 377 TMPFS_UNLOCK(tmp); 378 379 if (found) 380 return (tmpfs_alloc_vp(mp, node, LK_EXCLUSIVE, vpp)); 381 382 return (EINVAL); 383 } 384 385 /* ARGSUSED2 */ 386 static int 387 tmpfs_statfs(struct mount *mp, struct statfs *sbp) 388 { 389 struct tmpfs_mount *tmp; 390 size_t used; 391 392 tmp = VFS_TO_TMPFS(mp); 393 394 sbp->f_iosize = PAGE_SIZE; 395 sbp->f_bsize = PAGE_SIZE; 396 397 used = tmpfs_pages_used(tmp); 398 if (tmp->tm_pages_max != SIZE_MAX) 399 sbp->f_blocks = tmp->tm_pages_max; 400 else 401 sbp->f_blocks = used + tmpfs_mem_avail(); 402 if (sbp->f_blocks <= used) 403 sbp->f_bavail = 0; 404 else 405 sbp->f_bavail = sbp->f_blocks - used; 406 sbp->f_bfree = sbp->f_bavail; 407 used = tmp->tm_nodes_inuse; 408 sbp->f_files = tmp->tm_nodes_max; 409 if (sbp->f_files <= used) 410 sbp->f_ffree = 0; 411 else 412 sbp->f_ffree = sbp->f_files - used; 413 /* sbp->f_owner = tmp->tn_uid; */ 414 415 return 0; 416 } 417 418 static int 419 tmpfs_sync(struct mount *mp, int waitfor) 420 { 421 422 if (waitfor == MNT_SUSPEND) { 423 MNT_ILOCK(mp); 424 mp->mnt_kern_flag |= MNTK_SUSPEND2 | MNTK_SUSPENDED; 425 MNT_IUNLOCK(mp); 426 } 427 return (0); 428 } 429 430 /* 431 * tmpfs vfs operations. 432 */ 433 434 struct vfsops tmpfs_vfsops = { 435 .vfs_mount = tmpfs_mount, 436 .vfs_unmount = tmpfs_unmount, 437 .vfs_root = tmpfs_root, 438 .vfs_statfs = tmpfs_statfs, 439 .vfs_fhtovp = tmpfs_fhtovp, 440 .vfs_sync = tmpfs_sync, 441 }; 442 VFS_SET(tmpfs_vfsops, tmpfs, VFCF_JAIL); 443