tmpfs_vfsops.c revision 313092
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 FreeBSD's virtual memory 37 * sub-system to store file data and metadata in an efficient way. 38 * This means that it does not follow the structure of an on-disk file 39 * 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: stable/10/sys/fs/tmpfs/tmpfs_vfsops.c 313092 2017-02-02 13:36:07Z kib $"); 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/rwlock.h> 54#include <sys/stat.h> 55#include <sys/systm.h> 56#include <sys/sysctl.h> 57 58#include <vm/vm.h> 59#include <vm/vm_object.h> 60#include <vm/vm_param.h> 61 62#include <fs/tmpfs/tmpfs.h> 63 64/* 65 * Default permission for root node 66 */ 67#define TMPFS_DEFAULT_ROOT_MODE (S_IRWXU|S_IRGRP|S_IXGRP|S_IROTH|S_IXOTH) 68 69MALLOC_DEFINE(M_TMPFSMNT, "tmpfs mount", "tmpfs mount structures"); 70MALLOC_DEFINE(M_TMPFSNAME, "tmpfs name", "tmpfs file names"); 71 72static int tmpfs_mount(struct mount *); 73static int tmpfs_unmount(struct mount *, int); 74static int tmpfs_root(struct mount *, int flags, struct vnode **); 75static int tmpfs_fhtovp(struct mount *, struct fid *, int, 76 struct vnode **); 77static int tmpfs_statfs(struct mount *, struct statfs *); 78 79static const char *tmpfs_opts[] = { 80 "from", "size", "maxfilesize", "inodes", "uid", "gid", "mode", "export", 81 "union", NULL 82}; 83 84static const char *tmpfs_updateopts[] = { 85 "from", "export", NULL 86}; 87 88static int 89tmpfs_node_ctor(void *mem, int size, void *arg, int flags) 90{ 91 struct tmpfs_node *node = (struct tmpfs_node *)mem; 92 93 node->tn_gen++; 94 node->tn_size = 0; 95 node->tn_status = 0; 96 node->tn_flags = 0; 97 node->tn_links = 0; 98 node->tn_vnode = NULL; 99 node->tn_vpstate = 0; 100 101 return (0); 102} 103 104static void 105tmpfs_node_dtor(void *mem, int size, void *arg) 106{ 107 struct tmpfs_node *node = (struct tmpfs_node *)mem; 108 node->tn_type = VNON; 109} 110 111static int 112tmpfs_node_init(void *mem, int size, int flags) 113{ 114 struct tmpfs_node *node = (struct tmpfs_node *)mem; 115 node->tn_id = 0; 116 117 mtx_init(&node->tn_interlock, "tmpfs node interlock", NULL, MTX_DEF); 118 node->tn_gen = arc4random(); 119 120 return (0); 121} 122 123static void 124tmpfs_node_fini(void *mem, int size) 125{ 126 struct tmpfs_node *node = (struct tmpfs_node *)mem; 127 128 mtx_destroy(&node->tn_interlock); 129} 130 131static int 132tmpfs_mount(struct mount *mp) 133{ 134 const size_t nodes_per_page = howmany(PAGE_SIZE, 135 sizeof(struct tmpfs_dirent) + sizeof(struct tmpfs_node)); 136 struct tmpfs_mount *tmp; 137 struct tmpfs_node *root; 138 struct thread *td = curthread; 139 int error; 140 /* Size counters. */ 141 u_quad_t pages; 142 off_t nodes_max, size_max, maxfilesize; 143 144 /* Root node attributes. */ 145 uid_t root_uid; 146 gid_t root_gid; 147 mode_t root_mode; 148 149 struct vattr va; 150 151 if (!prison_allow(td->td_ucred, PR_ALLOW_MOUNT_TMPFS)) 152 return (EPERM); 153 154 if (vfs_filteropt(mp->mnt_optnew, tmpfs_opts)) 155 return (EINVAL); 156 157 if (mp->mnt_flag & MNT_UPDATE) { 158 /* Only support update mounts for certain options. */ 159 if (vfs_filteropt(mp->mnt_optnew, tmpfs_updateopts) != 0) 160 return (EOPNOTSUPP); 161 if (vfs_flagopt(mp->mnt_optnew, "ro", NULL, 0) != 162 ((struct tmpfs_mount *)mp->mnt_data)->tm_ronly) 163 return (EOPNOTSUPP); 164 return (0); 165 } 166 167 vn_lock(mp->mnt_vnodecovered, LK_SHARED | LK_RETRY); 168 error = VOP_GETATTR(mp->mnt_vnodecovered, &va, mp->mnt_cred); 169 VOP_UNLOCK(mp->mnt_vnodecovered, 0); 170 if (error) 171 return (error); 172 173 if (mp->mnt_cred->cr_ruid != 0 || 174 vfs_scanopt(mp->mnt_optnew, "gid", "%d", &root_gid) != 1) 175 root_gid = va.va_gid; 176 if (mp->mnt_cred->cr_ruid != 0 || 177 vfs_scanopt(mp->mnt_optnew, "uid", "%d", &root_uid) != 1) 178 root_uid = va.va_uid; 179 if (mp->mnt_cred->cr_ruid != 0 || 180 vfs_scanopt(mp->mnt_optnew, "mode", "%ho", &root_mode) != 1) 181 root_mode = va.va_mode; 182 if (vfs_getopt_size(mp->mnt_optnew, "inodes", &nodes_max) != 0) 183 nodes_max = 0; 184 if (vfs_getopt_size(mp->mnt_optnew, "size", &size_max) != 0) 185 size_max = 0; 186 if (vfs_getopt_size(mp->mnt_optnew, "maxfilesize", &maxfilesize) != 0) 187 maxfilesize = 0; 188 189 /* Do not allow mounts if we do not have enough memory to preserve 190 * the minimum reserved pages. */ 191 if (tmpfs_mem_avail() < TMPFS_PAGES_MINRESERVED) 192 return (ENOSPC); 193 194 /* Get the maximum number of memory pages this file system is 195 * allowed to use, based on the maximum size the user passed in 196 * the mount structure. A value of zero is treated as if the 197 * maximum available space was requested. */ 198 if (size_max == 0 || size_max > OFF_MAX - PAGE_SIZE || 199 (SIZE_MAX < OFF_MAX && size_max / PAGE_SIZE >= SIZE_MAX)) 200 pages = SIZE_MAX; 201 else { 202 size_max = roundup(size_max, PAGE_SIZE); 203 pages = howmany(size_max, PAGE_SIZE); 204 } 205 MPASS(pages > 0); 206 207 if (nodes_max <= 3) { 208 if (pages < INT_MAX / nodes_per_page) 209 nodes_max = pages * nodes_per_page; 210 else 211 nodes_max = INT_MAX; 212 } 213 if (nodes_max > INT_MAX) 214 nodes_max = INT_MAX; 215 MPASS(nodes_max >= 3); 216 217 /* Allocate the tmpfs mount structure and fill it. */ 218 tmp = (struct tmpfs_mount *)malloc(sizeof(struct tmpfs_mount), 219 M_TMPFSMNT, M_WAITOK | M_ZERO); 220 221 mtx_init(&tmp->tm_allnode_lock, "tmpfs allnode lock", NULL, MTX_DEF); 222 tmp->tm_nodes_max = nodes_max; 223 tmp->tm_nodes_inuse = 0; 224 tmp->tm_refcount = 1; 225 tmp->tm_maxfilesize = maxfilesize > 0 ? maxfilesize : OFF_MAX; 226 LIST_INIT(&tmp->tm_nodes_used); 227 228 tmp->tm_pages_max = pages; 229 tmp->tm_pages_used = 0; 230 tmp->tm_ino_unr = new_unrhdr(2, INT_MAX, &tmp->tm_allnode_lock); 231 tmp->tm_dirent_pool = uma_zcreate("TMPFS dirent", 232 sizeof(struct tmpfs_dirent), NULL, NULL, NULL, NULL, 233 UMA_ALIGN_PTR, 0); 234 tmp->tm_node_pool = uma_zcreate("TMPFS node", 235 sizeof(struct tmpfs_node), tmpfs_node_ctor, tmpfs_node_dtor, 236 tmpfs_node_init, tmpfs_node_fini, UMA_ALIGN_PTR, 0); 237 tmp->tm_ronly = (mp->mnt_flag & MNT_RDONLY) != 0; 238 239 /* Allocate the root node. */ 240 error = tmpfs_alloc_node(mp, tmp, VDIR, root_uid, root_gid, 241 root_mode & ALLPERMS, NULL, NULL, VNOVAL, &root); 242 243 if (error != 0 || root == NULL) { 244 uma_zdestroy(tmp->tm_node_pool); 245 uma_zdestroy(tmp->tm_dirent_pool); 246 delete_unrhdr(tmp->tm_ino_unr); 247 free(tmp, M_TMPFSMNT); 248 return (error); 249 } 250 KASSERT(root->tn_id == 2, 251 ("tmpfs root with invalid ino: %ju", (uintmax_t)root->tn_id)); 252 tmp->tm_root = root; 253 254 MNT_ILOCK(mp); 255 mp->mnt_flag |= MNT_LOCAL; 256 MNT_IUNLOCK(mp); 257 258 mp->mnt_data = tmp; 259 mp->mnt_stat.f_namemax = MAXNAMLEN; 260 vfs_getnewfsid(mp); 261 vfs_mountedfrom(mp, "tmpfs"); 262 263 return 0; 264} 265 266/* ARGSUSED2 */ 267static int 268tmpfs_unmount(struct mount *mp, int mntflags) 269{ 270 struct tmpfs_mount *tmp; 271 struct tmpfs_node *node; 272 int error, flags; 273 274 flags = (mntflags & MNT_FORCE) != 0 ? FORCECLOSE : 0; 275 tmp = VFS_TO_TMPFS(mp); 276 277 /* Stop writers */ 278 error = vfs_write_suspend_umnt(mp); 279 if (error != 0) 280 return (error); 281 /* 282 * At this point, nodes cannot be destroyed by any other 283 * thread because write suspension is started. 284 */ 285 286 for (;;) { 287 error = vflush(mp, 0, flags, curthread); 288 if (error != 0) { 289 vfs_write_resume(mp, VR_START_WRITE); 290 return (error); 291 } 292 MNT_ILOCK(mp); 293 if (mp->mnt_nvnodelistsize == 0) { 294 MNT_IUNLOCK(mp); 295 break; 296 } 297 MNT_IUNLOCK(mp); 298 if ((mntflags & MNT_FORCE) == 0) { 299 vfs_write_resume(mp, VR_START_WRITE); 300 return (EBUSY); 301 } 302 } 303 304 TMPFS_LOCK(tmp); 305 while ((node = LIST_FIRST(&tmp->tm_nodes_used)) != NULL) { 306 TMPFS_NODE_LOCK(node); 307 if (node->tn_type == VDIR) 308 tmpfs_dir_destroy(tmp, node); 309 if (tmpfs_free_node_locked(tmp, node, true)) 310 TMPFS_LOCK(tmp); 311 else 312 TMPFS_NODE_UNLOCK(node); 313 } 314 315 mp->mnt_data = NULL; 316 tmpfs_free_tmp(tmp); 317 vfs_write_resume(mp, VR_START_WRITE); 318 319 MNT_ILOCK(mp); 320 mp->mnt_flag &= ~MNT_LOCAL; 321 MNT_IUNLOCK(mp); 322 323 return (0); 324} 325 326void 327tmpfs_free_tmp(struct tmpfs_mount *tmp) 328{ 329 330 MPASS(tmp->tm_refcount > 0); 331 tmp->tm_refcount--; 332 if (tmp->tm_refcount > 0) { 333 TMPFS_UNLOCK(tmp); 334 return; 335 } 336 TMPFS_UNLOCK(tmp); 337 338 uma_zdestroy(tmp->tm_dirent_pool); 339 uma_zdestroy(tmp->tm_node_pool); 340 delete_unrhdr(tmp->tm_ino_unr); 341 342 mtx_destroy(&tmp->tm_allnode_lock); 343 MPASS(tmp->tm_pages_used == 0); 344 MPASS(tmp->tm_nodes_inuse == 0); 345 346 free(tmp, M_TMPFSMNT); 347} 348 349static int 350tmpfs_root(struct mount *mp, int flags, struct vnode **vpp) 351{ 352 int error; 353 354 error = tmpfs_alloc_vp(mp, VFS_TO_TMPFS(mp)->tm_root, flags, vpp); 355 if (error == 0) 356 (*vpp)->v_vflag |= VV_ROOT; 357 return (error); 358} 359 360static int 361tmpfs_fhtovp(struct mount *mp, struct fid *fhp, int flags, 362 struct vnode **vpp) 363{ 364 struct tmpfs_fid *tfhp; 365 struct tmpfs_mount *tmp; 366 struct tmpfs_node *node; 367 int error; 368 369 tmp = VFS_TO_TMPFS(mp); 370 371 tfhp = (struct tmpfs_fid *)fhp; 372 if (tfhp->tf_len != sizeof(struct tmpfs_fid)) 373 return (EINVAL); 374 375 if (tfhp->tf_id >= tmp->tm_nodes_max) 376 return (EINVAL); 377 378 TMPFS_LOCK(tmp); 379 LIST_FOREACH(node, &tmp->tm_nodes_used, tn_entries) { 380 if (node->tn_id == tfhp->tf_id && 381 node->tn_gen == tfhp->tf_gen) { 382 tmpfs_ref_node(node); 383 break; 384 } 385 } 386 TMPFS_UNLOCK(tmp); 387 388 if (node != NULL) { 389 error = tmpfs_alloc_vp(mp, node, LK_EXCLUSIVE, vpp); 390 tmpfs_free_node(tmp, node); 391 } else 392 error = EINVAL; 393 return (error); 394} 395 396/* ARGSUSED2 */ 397static int 398tmpfs_statfs(struct mount *mp, struct statfs *sbp) 399{ 400 struct tmpfs_mount *tmp; 401 size_t used; 402 403 tmp = VFS_TO_TMPFS(mp); 404 405 sbp->f_iosize = PAGE_SIZE; 406 sbp->f_bsize = PAGE_SIZE; 407 408 used = tmpfs_pages_used(tmp); 409 if (tmp->tm_pages_max != ULONG_MAX) 410 sbp->f_blocks = tmp->tm_pages_max; 411 else 412 sbp->f_blocks = used + tmpfs_mem_avail(); 413 if (sbp->f_blocks <= used) 414 sbp->f_bavail = 0; 415 else 416 sbp->f_bavail = sbp->f_blocks - used; 417 sbp->f_bfree = sbp->f_bavail; 418 used = tmp->tm_nodes_inuse; 419 sbp->f_files = tmp->tm_nodes_max; 420 if (sbp->f_files <= used) 421 sbp->f_ffree = 0; 422 else 423 sbp->f_ffree = sbp->f_files - used; 424 /* sbp->f_owner = tmp->tn_uid; */ 425 426 return 0; 427} 428 429static int 430tmpfs_sync(struct mount *mp, int waitfor) 431{ 432 struct vnode *vp, *mvp; 433 struct vm_object *obj; 434 435 if (waitfor == MNT_SUSPEND) { 436 MNT_ILOCK(mp); 437 mp->mnt_kern_flag |= MNTK_SUSPEND2 | MNTK_SUSPENDED; 438 MNT_IUNLOCK(mp); 439 } else if (waitfor == MNT_LAZY) { 440 /* 441 * Handle lazy updates of mtime from writes to mmaped 442 * regions. Use MNT_VNODE_FOREACH_ALL instead of 443 * MNT_VNODE_FOREACH_ACTIVE, since unmap of the 444 * tmpfs-backed vnode does not call vinactive(), due 445 * to vm object type is OBJT_SWAP. 446 */ 447 MNT_VNODE_FOREACH_ALL(vp, mp, mvp) { 448 if (vp->v_type != VREG) { 449 VI_UNLOCK(vp); 450 continue; 451 } 452 obj = vp->v_object; 453 KASSERT((obj->flags & (OBJ_TMPFS_NODE | OBJ_TMPFS)) == 454 (OBJ_TMPFS_NODE | OBJ_TMPFS), ("non-tmpfs obj")); 455 456 /* 457 * Unlocked read, avoid taking vnode lock if 458 * not needed. Lost update will be handled on 459 * the next call. 460 */ 461 if ((obj->flags & OBJ_TMPFS_DIRTY) == 0) { 462 VI_UNLOCK(vp); 463 continue; 464 } 465 if (vget(vp, LK_EXCLUSIVE | LK_RETRY | LK_INTERLOCK, 466 curthread) != 0) 467 continue; 468 tmpfs_check_mtime(vp); 469 vput(vp); 470 } 471 } 472 return (0); 473} 474 475/* 476 * tmpfs vfs operations. 477 */ 478 479struct vfsops tmpfs_vfsops = { 480 .vfs_mount = tmpfs_mount, 481 .vfs_unmount = tmpfs_unmount, 482 .vfs_root = tmpfs_root, 483 .vfs_statfs = tmpfs_statfs, 484 .vfs_fhtovp = tmpfs_fhtovp, 485 .vfs_sync = tmpfs_sync, 486}; 487VFS_SET(tmpfs_vfsops, tmpfs, VFCF_JAIL); 488