1 /* $NetBSD: tmpfs.h,v 1.26 2007/02/22 06:37:00 thorpej Exp $ */ 2 3 /*- 4 * SPDX-License-Identifier: BSD-2-Clause-NetBSD 5 * 6 * Copyright (c) 2005, 2006 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 * $FreeBSD$ 35 */ 36 37 #ifndef _FS_TMPFS_TMPFS_H_ 38 #define _FS_TMPFS_TMPFS_H_ 39 40 #include <sys/dirent.h> 41 #include <sys/mount.h> 42 #include <sys/queue.h> 43 #include <sys/vnode.h> 44 #include <sys/file.h> 45 #include <sys/lock.h> 46 #include <sys/mutex.h> 47 48 #include <sys/malloc.h> 49 #include <sys/systm.h> 50 #include <sys/tree.h> 51 #include <sys/vmmeter.h> 52 #include <vm/swap_pager.h> 53 54 MALLOC_DECLARE(M_TMPFSMNT); 55 MALLOC_DECLARE(M_TMPFSNAME); 56 57 /* 58 * Internal representation of a tmpfs directory entry. 59 */ 60 61 LIST_HEAD(tmpfs_dir_duphead, tmpfs_dirent); 62 63 struct tmpfs_dirent { 64 /* 65 * Depending on td_cookie flag entry can be of 3 types: 66 * - regular -- no hash collisions, stored in RB-Tree 67 * - duphead -- synthetic linked list head for dup entries 68 * - dup -- stored in linked list instead of RB-Tree 69 */ 70 union { 71 /* regular and duphead entry types */ 72 RB_ENTRY(tmpfs_dirent) td_entries; 73 74 /* dup entry type */ 75 struct { 76 LIST_ENTRY(tmpfs_dirent) entries; 77 LIST_ENTRY(tmpfs_dirent) index_entries; 78 } td_dup; 79 } uh; 80 81 uint32_t td_cookie; 82 uint32_t td_hash; 83 u_int td_namelen; 84 85 /* 86 * Pointer to the node this entry refers to. In case this field 87 * is NULL, the node is a whiteout. 88 */ 89 struct tmpfs_node * td_node; 90 91 union { 92 /* 93 * The name of the entry, allocated from a string pool. This 94 * string is not required to be zero-terminated. 95 */ 96 char * td_name; /* regular, dup */ 97 struct tmpfs_dir_duphead td_duphead; /* duphead */ 98 } ud; 99 }; 100 101 /* 102 * A directory in tmpfs holds a collection of directory entries, which 103 * in turn point to other files (which can be directories themselves). 104 * 105 * In tmpfs, this collection is managed by a RB-Tree, whose head is 106 * defined by the struct tmpfs_dir type. 107 * 108 * It is important to notice that directories do not have entries for . and 109 * .. as other file systems do. These can be generated when requested 110 * based on information available by other means, such as the pointer to 111 * the node itself in the former case or the pointer to the parent directory 112 * in the latter case. This is done to simplify tmpfs's code and, more 113 * importantly, to remove redundancy. 114 */ 115 RB_HEAD(tmpfs_dir, tmpfs_dirent); 116 117 /* 118 * Each entry in a directory has a cookie that identifies it. Cookies 119 * supersede offsets within directories because, given how tmpfs stores 120 * directories in memory, there is no such thing as an offset. 121 * 122 * The '.', '..' and the end of directory markers have fixed cookies which 123 * cannot collide with the cookies generated by other entries. The cookies 124 * for the other entries are generated based on the file name hash value or 125 * unique number in case of name hash collision. 126 * 127 * To preserve compatibility cookies are limited to 31 bits. 128 */ 129 130 #define TMPFS_DIRCOOKIE_DOT 0 131 #define TMPFS_DIRCOOKIE_DOTDOT 1 132 #define TMPFS_DIRCOOKIE_EOF 2 133 #define TMPFS_DIRCOOKIE_MASK ((off_t)0x3fffffffU) 134 #define TMPFS_DIRCOOKIE_MIN ((off_t)0x00000004U) 135 #define TMPFS_DIRCOOKIE_DUP ((off_t)0x40000000U) 136 #define TMPFS_DIRCOOKIE_DUPHEAD ((off_t)0x80000000U) 137 #define TMPFS_DIRCOOKIE_DUP_MIN TMPFS_DIRCOOKIE_DUP 138 #define TMPFS_DIRCOOKIE_DUP_MAX \ 139 (TMPFS_DIRCOOKIE_DUP | TMPFS_DIRCOOKIE_MASK) 140 141 /* 142 * Internal representation of a tmpfs file system node. 143 * 144 * This structure is splitted in two parts: one holds attributes common 145 * to all file types and the other holds data that is only applicable to 146 * a particular type. The code must be careful to only access those 147 * attributes that are actually allowed by the node's type. 148 * 149 * Below is the key of locks used to protected the fields in the following 150 * structures. 151 * (v) vnode lock in exclusive mode 152 * (vi) vnode lock in exclusive mode, or vnode lock in shared vnode and 153 * tn_interlock 154 * (i) tn_interlock 155 * (m) tmpfs_mount tm_allnode_lock 156 * (c) stable after creation 157 */ 158 struct tmpfs_node { 159 /* 160 * Doubly-linked list entry which links all existing nodes for 161 * a single file system. This is provided to ease the removal 162 * of all nodes during the unmount operation, and to support 163 * the implementation of VOP_VNTOCNP(). tn_attached is false 164 * when the node is removed from list and unlocked. 165 */ 166 LIST_ENTRY(tmpfs_node) tn_entries; /* (m) */ 167 bool tn_attached; /* (m) */ 168 169 /* 170 * The node's type. Any of 'VBLK', 'VCHR', 'VDIR', 'VFIFO', 171 * 'VLNK', 'VREG' and 'VSOCK' is allowed. The usage of vnode 172 * types instead of a custom enumeration is to make things simpler 173 * and faster, as we do not need to convert between two types. 174 */ 175 enum vtype tn_type; /* (c) */ 176 177 /* Node identifier. */ 178 ino_t tn_id; /* (c) */ 179 180 /* 181 * Node's internal status. This is used by several file system 182 * operations to do modifications to the node in a delayed 183 * fashion. 184 */ 185 int tn_status; /* (vi) */ 186 #define TMPFS_NODE_ACCESSED (1 << 1) 187 #define TMPFS_NODE_MODIFIED (1 << 2) 188 #define TMPFS_NODE_CHANGED (1 << 3) 189 190 /* 191 * The node size. It does not necessarily match the real amount 192 * of memory consumed by it. 193 */ 194 off_t tn_size; /* (v) */ 195 196 /* Generic node attributes. */ 197 uid_t tn_uid; /* (v) */ 198 gid_t tn_gid; /* (v) */ 199 mode_t tn_mode; /* (v) */ 200 u_long tn_flags; /* (v) */ 201 nlink_t tn_links; /* (v) */ 202 struct timespec tn_atime; /* (vi) */ 203 struct timespec tn_mtime; /* (vi) */ 204 struct timespec tn_ctime; /* (vi) */ 205 struct timespec tn_birthtime; /* (v) */ 206 unsigned long tn_gen; /* (c) */ 207 208 /* 209 * As there is a single vnode for each active file within the 210 * system, care has to be taken to avoid allocating more than one 211 * vnode per file. In order to do this, a bidirectional association 212 * is kept between vnodes and nodes. 213 * 214 * Whenever a vnode is allocated, its v_data field is updated to 215 * point to the node it references. At the same time, the node's 216 * tn_vnode field is modified to point to the new vnode representing 217 * it. Further attempts to allocate a vnode for this same node will 218 * result in returning a new reference to the value stored in 219 * tn_vnode. 220 * 221 * May be NULL when the node is unused (that is, no vnode has been 222 * allocated for it or it has been reclaimed). 223 */ 224 struct vnode * tn_vnode; /* (i) */ 225 226 /* 227 * Interlock to protect tn_vpstate, and tn_status under shared 228 * vnode lock. 229 */ 230 struct mtx tn_interlock; 231 232 /* 233 * Identify if current node has vnode assiocate with 234 * or allocating vnode. 235 */ 236 int tn_vpstate; /* (i) */ 237 238 /* Transient refcounter on this node. */ 239 u_int tn_refcount; /* (m) + (i) */ 240 241 /* misc data field for different tn_type node */ 242 union { 243 /* Valid when tn_type == VBLK || tn_type == VCHR. */ 244 dev_t tn_rdev; /* (c) */ 245 246 /* Valid when tn_type == VDIR. */ 247 struct tn_dir { 248 /* 249 * Pointer to the parent directory. The root 250 * directory has a pointer to itself in this field; 251 * this property identifies the root node. 252 */ 253 struct tmpfs_node * tn_parent; 254 255 /* 256 * Head of a tree that links the contents of 257 * the directory together. 258 */ 259 struct tmpfs_dir tn_dirhead; 260 261 /* 262 * Head of a list the contains fake directory entries 263 * heads, i.e. entries with TMPFS_DIRCOOKIE_DUPHEAD 264 * flag. 265 */ 266 struct tmpfs_dir_duphead tn_dupindex; 267 268 /* 269 * Number and pointer of the first directory entry 270 * returned by the readdir operation if it were 271 * called again to continue reading data from the 272 * same directory as before. This is used to speed 273 * up reads of long directories, assuming that no 274 * more than one read is in progress at a given time. 275 * Otherwise, these values are discarded. 276 */ 277 off_t tn_readdir_lastn; 278 struct tmpfs_dirent * tn_readdir_lastp; 279 } tn_dir; 280 281 /* Valid when tn_type == VLNK. */ 282 /* The link's target, allocated from a string pool. */ 283 char * tn_link; /* (c) */ 284 285 /* Valid when tn_type == VREG. */ 286 struct tn_reg { 287 /* 288 * The contents of regular files stored in a 289 * tmpfs file system are represented by a 290 * single anonymous memory object (aobj, for 291 * short). The aobj provides direct access to 292 * any position within the file. It is a task 293 * of the memory management subsystem to issue 294 * the required page ins or page outs whenever 295 * a position within the file is accessed. 296 */ 297 vm_object_t tn_aobj; /* (c) */ 298 } tn_reg; 299 } tn_spec; /* (v) */ 300 }; 301 LIST_HEAD(tmpfs_node_list, tmpfs_node); 302 303 #define tn_rdev tn_spec.tn_rdev 304 #define tn_dir tn_spec.tn_dir 305 #define tn_link tn_spec.tn_link 306 #define tn_reg tn_spec.tn_reg 307 #define tn_fifo tn_spec.tn_fifo 308 309 #define TMPFS_NODE_LOCK(node) mtx_lock(&(node)->tn_interlock) 310 #define TMPFS_NODE_UNLOCK(node) mtx_unlock(&(node)->tn_interlock) 311 #define TMPFS_NODE_MTX(node) (&(node)->tn_interlock) 312 #define TMPFS_NODE_ASSERT_LOCKED(node) mtx_assert(TMPFS_NODE_MTX(node), \ 313 MA_OWNED) 314 315 #ifdef INVARIANTS 316 #define TMPFS_ASSERT_LOCKED(node) do { \ 317 MPASS((node) != NULL); \ 318 MPASS((node)->tn_vnode != NULL); \ 319 ASSERT_VOP_LOCKED((node)->tn_vnode, "tmpfs assert"); \ 320 } while (0) 321 #else 322 #define TMPFS_ASSERT_LOCKED(node) (void)0 323 #endif 324 325 #define TMPFS_VNODE_ALLOCATING 1 326 #define TMPFS_VNODE_WANT 2 327 #define TMPFS_VNODE_DOOMED 4 328 #define TMPFS_VNODE_WRECLAIM 8 329 330 /* 331 * Internal representation of a tmpfs mount point. 332 */ 333 struct tmpfs_mount { 334 /* 335 * Maximum number of memory pages available for use by the file 336 * system, set during mount time. This variable must never be 337 * used directly as it may be bigger than the current amount of 338 * free memory; in the extreme case, it will hold the ULONG_MAX 339 * value. 340 */ 341 u_long tm_pages_max; 342 343 /* Number of pages in use by the file system. */ 344 u_long tm_pages_used; 345 346 /* 347 * Pointer to the node representing the root directory of this 348 * file system. 349 */ 350 struct tmpfs_node * tm_root; 351 352 /* 353 * Maximum number of possible nodes for this file system; set 354 * during mount time. We need a hard limit on the maximum number 355 * of nodes to avoid allocating too much of them; their objects 356 * cannot be released until the file system is unmounted. 357 * Otherwise, we could easily run out of memory by creating lots 358 * of empty files and then simply removing them. 359 */ 360 ino_t tm_nodes_max; 361 362 /* unrhdr used to allocate inode numbers */ 363 struct unrhdr * tm_ino_unr; 364 365 /* Number of nodes currently that are in use. */ 366 ino_t tm_nodes_inuse; 367 368 /* Refcounter on this struct tmpfs_mount. */ 369 uint64_t tm_refcount; 370 371 /* maximum representable file size */ 372 u_int64_t tm_maxfilesize; 373 374 /* 375 * The used list contains all nodes that are currently used by 376 * the file system; i.e., they refer to existing files. 377 */ 378 struct tmpfs_node_list tm_nodes_used; 379 380 /* All node lock to protect the node list and tmp_pages_used. */ 381 struct mtx tm_allnode_lock; 382 383 /* Zones used to store file system meta data, per tmpfs mount. */ 384 uma_zone_t tm_dirent_pool; 385 uma_zone_t tm_node_pool; 386 387 /* Read-only status. */ 388 bool tm_ronly; 389 /* Do not use namecache. */ 390 bool tm_nonc; 391 }; 392 #define TMPFS_LOCK(tm) mtx_lock(&(tm)->tm_allnode_lock) 393 #define TMPFS_UNLOCK(tm) mtx_unlock(&(tm)->tm_allnode_lock) 394 #define TMPFS_MP_ASSERT_LOCKED(tm) mtx_assert(&(tm)->tm_allnode_lock, MA_OWNED) 395 396 /* 397 * This structure maps a file identifier to a tmpfs node. Used by the 398 * NFS code. 399 */ 400 struct tmpfs_fid { 401 uint16_t tf_len; 402 uint16_t tf_pad; 403 ino_t tf_id; 404 unsigned long tf_gen; 405 }; 406 407 struct tmpfs_dir_cursor { 408 struct tmpfs_dirent *tdc_current; 409 struct tmpfs_dirent *tdc_tree; 410 }; 411 412 #ifdef _KERNEL 413 /* 414 * Prototypes for tmpfs_subr.c. 415 */ 416 417 void tmpfs_ref_node(struct tmpfs_node *node); 418 void tmpfs_ref_node_locked(struct tmpfs_node *node); 419 int tmpfs_alloc_node(struct mount *mp, struct tmpfs_mount *, enum vtype, 420 uid_t uid, gid_t gid, mode_t mode, struct tmpfs_node *, 421 char *, dev_t, struct tmpfs_node **); 422 void tmpfs_free_node(struct tmpfs_mount *, struct tmpfs_node *); 423 bool tmpfs_free_node_locked(struct tmpfs_mount *, struct tmpfs_node *, bool); 424 void tmpfs_free_tmp(struct tmpfs_mount *); 425 int tmpfs_alloc_dirent(struct tmpfs_mount *, struct tmpfs_node *, 426 const char *, u_int, struct tmpfs_dirent **); 427 void tmpfs_free_dirent(struct tmpfs_mount *, struct tmpfs_dirent *); 428 void tmpfs_dirent_init(struct tmpfs_dirent *, const char *, u_int); 429 void tmpfs_destroy_vobject(struct vnode *vp, vm_object_t obj); 430 int tmpfs_alloc_vp(struct mount *, struct tmpfs_node *, int, 431 struct vnode **); 432 void tmpfs_free_vp(struct vnode *); 433 int tmpfs_alloc_file(struct vnode *, struct vnode **, struct vattr *, 434 struct componentname *, char *); 435 void tmpfs_check_mtime(struct vnode *); 436 void tmpfs_dir_attach(struct vnode *, struct tmpfs_dirent *); 437 void tmpfs_dir_detach(struct vnode *, struct tmpfs_dirent *); 438 void tmpfs_dir_destroy(struct tmpfs_mount *, struct tmpfs_node *); 439 struct tmpfs_dirent * tmpfs_dir_lookup(struct tmpfs_node *node, 440 struct tmpfs_node *f, 441 struct componentname *cnp); 442 int tmpfs_dir_getdents(struct tmpfs_node *, struct uio *, int, 443 u_long *, int *); 444 int tmpfs_dir_whiteout_add(struct vnode *, struct componentname *); 445 void tmpfs_dir_whiteout_remove(struct vnode *, struct componentname *); 446 int tmpfs_reg_resize(struct vnode *, off_t, boolean_t); 447 int tmpfs_chflags(struct vnode *, u_long, struct ucred *, struct thread *); 448 int tmpfs_chmod(struct vnode *, mode_t, struct ucred *, struct thread *); 449 int tmpfs_chown(struct vnode *, uid_t, gid_t, struct ucred *, 450 struct thread *); 451 int tmpfs_chsize(struct vnode *, u_quad_t, struct ucred *, struct thread *); 452 int tmpfs_chtimes(struct vnode *, struct vattr *, struct ucred *cred, 453 struct thread *); 454 void tmpfs_itimes(struct vnode *, const struct timespec *, 455 const struct timespec *); 456 457 void tmpfs_set_status(struct tmpfs_node *node, int status); 458 void tmpfs_update(struct vnode *); 459 int tmpfs_truncate(struct vnode *, off_t); 460 struct tmpfs_dirent *tmpfs_dir_first(struct tmpfs_node *dnode, 461 struct tmpfs_dir_cursor *dc); 462 struct tmpfs_dirent *tmpfs_dir_next(struct tmpfs_node *dnode, 463 struct tmpfs_dir_cursor *dc); 464 465 /* 466 * Convenience macros to simplify some logical expressions. 467 */ 468 #define IMPLIES(a, b) (!(a) || (b)) 469 #define IFF(a, b) (IMPLIES(a, b) && IMPLIES(b, a)) 470 471 /* 472 * Checks that the directory entry pointed by 'de' matches the name 'name' 473 * with a length of 'len'. 474 */ 475 #define TMPFS_DIRENT_MATCHES(de, name, len) \ 476 (de->td_namelen == len && \ 477 bcmp((de)->ud.td_name, (name), (de)->td_namelen) == 0) 478 479 /* 480 * Ensures that the node pointed by 'node' is a directory and that its 481 * contents are consistent with respect to directories. 482 */ 483 #define TMPFS_VALIDATE_DIR(node) do { \ 484 MPASS((node)->tn_type == VDIR); \ 485 MPASS((node)->tn_size % sizeof(struct tmpfs_dirent) == 0); \ 486 } while (0) 487 488 /* 489 * Amount of memory pages to reserve for the system (e.g., to not use by 490 * tmpfs). 491 */ 492 #define TMPFS_PAGES_MINRESERVED (4 * 1024 * 1024 / PAGE_SIZE) 493 494 size_t tmpfs_mem_avail(void); 495 496 size_t tmpfs_pages_used(struct tmpfs_mount *tmp); 497 498 #endif 499 500 /* 501 * Macros/functions to convert from generic data structures to tmpfs 502 * specific ones. 503 */ 504 505 static inline struct tmpfs_mount * 506 VFS_TO_TMPFS(struct mount *mp) 507 { 508 struct tmpfs_mount *tmp; 509 510 MPASS(mp != NULL && mp->mnt_data != NULL); 511 tmp = (struct tmpfs_mount *)mp->mnt_data; 512 return (tmp); 513 } 514 515 static inline struct tmpfs_node * 516 VP_TO_TMPFS_NODE(struct vnode *vp) 517 { 518 struct tmpfs_node *node; 519 520 MPASS(vp != NULL && vp->v_data != NULL); 521 node = (struct tmpfs_node *)vp->v_data; 522 return (node); 523 } 524 525 static inline struct tmpfs_node * 526 VP_TO_TMPFS_DIR(struct vnode *vp) 527 { 528 struct tmpfs_node *node; 529 530 node = VP_TO_TMPFS_NODE(vp); 531 TMPFS_VALIDATE_DIR(node); 532 return (node); 533 } 534 535 static inline bool 536 tmpfs_use_nc(struct vnode *vp) 537 { 538 539 return (!(VFS_TO_TMPFS(vp->v_mount)->tm_nonc)); 540 } 541 542 #endif /* _FS_TMPFS_TMPFS_H_ */ 543