1 /* $NetBSD: tmpfs.h,v 1.18 2006/03/31 20:27:49 riz 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 * 3. All advertising materials mentioning features or use of this software 20 * must display the following acknowledgement: 21 * This product includes software developed by the NetBSD 22 * Foundation, Inc. and its contributors. 23 * 4. Neither the name of The NetBSD Foundation nor the names of its 24 * contributors may be used to endorse or promote products derived 25 * from this software without specific prior written permission. 26 * 27 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 28 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 29 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 30 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 31 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 32 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 33 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 34 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 35 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 36 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 37 * POSSIBILITY OF SUCH DAMAGE. 38 * 39 * $FreeBSD$ 40 */ 41 42 #ifndef _FS_TMPFS_TMPFS_H_ 43 #define _FS_TMPFS_TMPFS_H_ 44 45 /* --------------------------------------------------------------------- 46 * KERNEL-SPECIFIC DEFINITIONS 47 * --------------------------------------------------------------------- */ 48 #include <sys/dirent.h> 49 #include <sys/mount.h> 50 #include <sys/queue.h> 51 #include <sys/vnode.h> 52 #include <sys/file.h> 53 #include <sys/lock.h> 54 #include <sys/mutex.h> 55 56 /* --------------------------------------------------------------------- */ 57 #include <sys/malloc.h> 58 #include <sys/systm.h> 59 #include <sys/vmmeter.h> 60 #include <vm/swap_pager.h> 61 62 MALLOC_DECLARE(M_TMPFSMNT); 63 MALLOC_DECLARE(M_TMPFSNAME); 64 65 /* --------------------------------------------------------------------- */ 66 67 /* 68 * Internal representation of a tmpfs directory entry. 69 */ 70 struct tmpfs_dirent { 71 TAILQ_ENTRY(tmpfs_dirent) td_entries; 72 73 /* Length of the name stored in this directory entry. This avoids 74 * the need to recalculate it every time the name is used. */ 75 uint16_t td_namelen; 76 77 /* The name of the entry, allocated from a string pool. This 78 * string is not required to be zero-terminated; therefore, the 79 * td_namelen field must always be used when accessing its value. */ 80 char * td_name; 81 82 /* Pointer to the node this entry refers to. */ 83 struct tmpfs_node * td_node; 84 }; 85 86 /* A directory in tmpfs holds a sorted list of directory entries, which in 87 * turn point to other files (which can be directories themselves). 88 * 89 * In tmpfs, this list is managed by a tail queue, whose head is defined by 90 * the struct tmpfs_dir type. 91 * 92 * It is imporant to notice that directories do not have entries for . and 93 * .. as other file systems do. These can be generated when requested 94 * based on information available by other means, such as the pointer to 95 * the node itself in the former case or the pointer to the parent directory 96 * in the latter case. This is done to simplify tmpfs's code and, more 97 * importantly, to remove redundancy. */ 98 TAILQ_HEAD(tmpfs_dir, tmpfs_dirent); 99 100 #define TMPFS_DIRCOOKIE(dirent) ((off_t)(uintptr_t)(dirent)) 101 #define TMPFS_DIRCOOKIE_DOT 0 102 #define TMPFS_DIRCOOKIE_DOTDOT 1 103 #define TMPFS_DIRCOOKIE_EOF 2 104 105 /* --------------------------------------------------------------------- */ 106 107 /* 108 * Internal representation of a tmpfs file system node. 109 * 110 * This structure is splitted in two parts: one holds attributes common 111 * to all file types and the other holds data that is only applicable to 112 * a particular type. The code must be careful to only access those 113 * attributes that are actually allowed by the node's type. 114 * 115 * 116 * Below is the key of locks used to protected the fields in the following 117 * structures. 118 * 119 */ 120 struct tmpfs_node { 121 /* Doubly-linked list entry which links all existing nodes for a 122 * single file system. This is provided to ease the removal of 123 * all nodes during the unmount operation. */ 124 LIST_ENTRY(tmpfs_node) tn_entries; 125 126 /* The node's type. Any of 'VBLK', 'VCHR', 'VDIR', 'VFIFO', 127 * 'VLNK', 'VREG' and 'VSOCK' is allowed. The usage of vnode 128 * types instead of a custom enumeration is to make things simpler 129 * and faster, as we do not need to convert between two types. */ 130 enum vtype tn_type; 131 132 /* Node identifier. */ 133 ino_t tn_id; 134 135 /* Node's internal status. This is used by several file system 136 * operations to do modifications to the node in a delayed 137 * fashion. */ 138 int tn_status; 139 #define TMPFS_NODE_ACCESSED (1 << 1) 140 #define TMPFS_NODE_MODIFIED (1 << 2) 141 #define TMPFS_NODE_CHANGED (1 << 3) 142 143 /* The node size. It does not necessarily match the real amount 144 * of memory consumed by it. */ 145 off_t tn_size; 146 147 /* Generic node attributes. */ 148 uid_t tn_uid; 149 gid_t tn_gid; 150 mode_t tn_mode; 151 int tn_flags; 152 nlink_t tn_links; 153 struct timespec tn_atime; 154 struct timespec tn_mtime; 155 struct timespec tn_ctime; 156 struct timespec tn_birthtime; 157 unsigned long tn_gen; 158 159 /* Head of byte-level lock list (used by tmpfs_advlock). */ 160 struct lockf * tn_lockf; 161 162 /* As there is a single vnode for each active file within the 163 * system, care has to be taken to avoid allocating more than one 164 * vnode per file. In order to do this, a bidirectional association 165 * is kept between vnodes and nodes. 166 * 167 * Whenever a vnode is allocated, its v_data field is updated to 168 * point to the node it references. At the same time, the node's 169 * tn_vnode field is modified to point to the new vnode representing 170 * it. Further attempts to allocate a vnode for this same node will 171 * result in returning a new reference to the value stored in 172 * tn_vnode. 173 * 174 * May be NULL when the node is unused (that is, no vnode has been 175 * allocated for it or it has been reclaimed). */ 176 struct vnode * tn_vnode; 177 178 /* Pointer to the node returned by tmpfs_lookup() after doing a 179 * delete or a rename lookup; its value is only valid in these two 180 * situations. In case we were looking up . or .., it holds a null 181 * pointer. */ 182 struct tmpfs_dirent * tn_lookup_dirent; 183 184 /* interlock to protect tn_vpstate */ 185 struct mtx tn_interlock; 186 187 /* Identify if current node has vnode assiocate with 188 * or allocating vnode. 189 */ 190 int tn_vpstate; 191 192 /* misc data field for different tn_type node */ 193 union { 194 /* Valid when tn_type == VBLK || tn_type == VCHR. */ 195 dev_t tn_rdev; 196 197 /* Valid when tn_type == VDIR. */ 198 struct tn_dir{ 199 /* Pointer to the parent directory. The root 200 * directory has a pointer to itself in this field; 201 * this property identifies the root node. */ 202 struct tmpfs_node * tn_parent; 203 204 /* Head of a tail-queue that links the contents of 205 * the directory together. See above for a 206 * description of its contents. */ 207 struct tmpfs_dir tn_dirhead; 208 209 /* Number and pointer of the first directory entry 210 * returned by the readdir operation if it were 211 * called again to continue reading data from the 212 * same directory as before. This is used to speed 213 * up reads of long directories, assuming that no 214 * more than one read is in progress at a given time. 215 * Otherwise, these values are discarded and a linear 216 * scan is performed from the beginning up to the 217 * point where readdir starts returning values. */ 218 off_t tn_readdir_lastn; 219 struct tmpfs_dirent * tn_readdir_lastp; 220 }tn_dir; 221 222 /* Valid when tn_type == VLNK. */ 223 /* The link's target, allocated from a string pool. */ 224 char * tn_link; 225 226 /* Valid when tn_type == VREG. */ 227 struct tn_reg { 228 /* The contents of regular files stored in a tmpfs 229 * file system are represented by a single anonymous 230 * memory object (aobj, for short). The aobj provides 231 * direct access to any position within the file, 232 * because its contents are always mapped in a 233 * contiguous region of virtual memory. It is a task 234 * of the memory management subsystem (see uvm(9)) to 235 * issue the required page ins or page outs whenever 236 * a position within the file is accessed. */ 237 vm_object_t tn_aobj; 238 size_t tn_aobj_pages; 239 240 }tn_reg; 241 242 /* Valid when tn_type = VFIFO */ 243 struct tn_fifo { 244 fo_rdwr_t *tn_fo_read; 245 fo_rdwr_t *tn_fo_write; 246 }tn_fifo; 247 }tn_spec; 248 }; 249 LIST_HEAD(tmpfs_node_list, tmpfs_node); 250 251 #define tn_rdev tn_spec.tn_rdev 252 #define tn_dir tn_spec.tn_dir 253 #define tn_link tn_spec.tn_link 254 #define tn_reg tn_spec.tn_reg 255 #define tn_fifo tn_spec.tn_fifo 256 257 #define TMPFS_NODE_LOCK(node) mtx_lock(&(node)->tn_interlock) 258 #define TMPFS_NODE_UNLOCK(node) mtx_unlock(&(node)->tn_interlock) 259 260 #define TMPFS_VNODE_ALLOCATING 1 261 #define TMPFS_VNODE_WANT 2 262 /* --------------------------------------------------------------------- */ 263 264 /* 265 * Internal representation of a tmpfs mount point. 266 */ 267 struct tmpfs_mount { 268 /* Maximum number of memory pages available for use by the file 269 * system, set during mount time. This variable must never be 270 * used directly as it may be bigger than the current amount of 271 * free memory; in the extreme case, it will hold the SIZE_MAX 272 * value. Instead, use the TMPFS_PAGES_MAX macro. */ 273 size_t tm_pages_max; 274 275 /* Number of pages in use by the file system. Cannot be bigger 276 * than the value returned by TMPFS_PAGES_MAX in any case. */ 277 size_t tm_pages_used; 278 279 /* Pointer to the node representing the root directory of this 280 * file system. */ 281 struct tmpfs_node * tm_root; 282 283 /* Maximum number of possible nodes for this file system; set 284 * during mount time. We need a hard limit on the maximum number 285 * of nodes to avoid allocating too much of them; their objects 286 * cannot be released until the file system is unmounted. 287 * Otherwise, we could easily run out of memory by creating lots 288 * of empty files and then simply removing them. */ 289 ino_t tm_nodes_max; 290 291 /* unrhdr used to allocate inode numbers */ 292 struct unrhdr * tm_ino_unr; 293 294 /* Number of nodes currently that are in use. */ 295 ino_t tm_nodes_inuse; 296 297 /* maximum representable file size */ 298 u_int64_t tm_maxfilesize; 299 300 /* Nodes are organized in two different lists. The used list 301 * contains all nodes that are currently used by the file system; 302 * i.e., they refer to existing files. The available list contains 303 * all nodes that are currently available for use by new files. 304 * Nodes must be kept in this list (instead of deleting them) 305 * because we need to keep track of their generation number (tn_gen 306 * field). 307 * 308 * Note that nodes are lazily allocated: if the available list is 309 * empty and we have enough space to create more nodes, they will be 310 * created and inserted in the used list. Once these are released, 311 * they will go into the available list, remaining alive until the 312 * file system is unmounted. */ 313 struct tmpfs_node_list tm_nodes_used; 314 315 /* All node lock to protect the node list and tmp_pages_used */ 316 struct mtx allnode_lock; 317 318 /* Pools used to store file system meta data. These are not shared 319 * across several instances of tmpfs for the reasons described in 320 * tmpfs_pool.c. */ 321 uma_zone_t tm_dirent_pool; 322 uma_zone_t tm_node_pool; 323 }; 324 #define TMPFS_LOCK(tm) mtx_lock(&(tm)->allnode_lock) 325 #define TMPFS_UNLOCK(tm) mtx_unlock(&(tm)->allnode_lock) 326 327 /* --------------------------------------------------------------------- */ 328 329 /* 330 * This structure maps a file identifier to a tmpfs node. Used by the 331 * NFS code. 332 */ 333 struct tmpfs_fid { 334 uint16_t tf_len; 335 uint16_t tf_pad; 336 ino_t tf_id; 337 unsigned long tf_gen; 338 }; 339 340 /* --------------------------------------------------------------------- */ 341 342 #ifdef _KERNEL 343 /* 344 * Prototypes for tmpfs_subr.c. 345 */ 346 347 int tmpfs_alloc_node(struct tmpfs_mount *, enum vtype, 348 uid_t uid, gid_t gid, mode_t mode, struct tmpfs_node *, 349 char *, dev_t, struct thread *, struct tmpfs_node **); 350 void tmpfs_free_node(struct tmpfs_mount *, struct tmpfs_node *); 351 int tmpfs_alloc_dirent(struct tmpfs_mount *, struct tmpfs_node *, 352 const char *, uint16_t, struct tmpfs_dirent **); 353 void tmpfs_free_dirent(struct tmpfs_mount *, struct tmpfs_dirent *, 354 boolean_t); 355 int tmpfs_alloc_vp(struct mount *, struct tmpfs_node *, struct vnode **, 356 struct thread *td); 357 void tmpfs_free_vp(struct vnode *); 358 int tmpfs_alloc_file(struct vnode *, struct vnode **, struct vattr *, 359 struct componentname *, char *); 360 void tmpfs_dir_attach(struct vnode *, struct tmpfs_dirent *); 361 void tmpfs_dir_detach(struct vnode *, struct tmpfs_dirent *); 362 struct tmpfs_dirent * tmpfs_dir_lookup(struct tmpfs_node *node, 363 struct componentname *cnp); 364 int tmpfs_dir_getdotdent(struct tmpfs_node *, struct uio *); 365 int tmpfs_dir_getdotdotdent(struct tmpfs_node *, struct uio *); 366 struct tmpfs_dirent * tmpfs_dir_lookupbycookie(struct tmpfs_node *, off_t); 367 int tmpfs_dir_getdents(struct tmpfs_node *, struct uio *, off_t *); 368 int tmpfs_reg_resize(struct vnode *, off_t); 369 int tmpfs_chflags(struct vnode *, int, struct ucred *, struct thread *); 370 int tmpfs_chmod(struct vnode *, mode_t, struct ucred *, struct thread *); 371 int tmpfs_chown(struct vnode *, uid_t, gid_t, struct ucred *, 372 struct thread *); 373 int tmpfs_chsize(struct vnode *, u_quad_t, struct ucred *, struct thread *); 374 int tmpfs_chtimes(struct vnode *, struct timespec *, struct timespec *, 375 struct timespec *, int, struct ucred *, struct thread *); 376 void tmpfs_itimes(struct vnode *, const struct timespec *, 377 const struct timespec *); 378 379 void tmpfs_update(struct vnode *); 380 int tmpfs_truncate(struct vnode *, off_t); 381 382 /* --------------------------------------------------------------------- */ 383 384 /* 385 * Convenience macros to simplify some logical expressions. 386 */ 387 #define IMPLIES(a, b) (!(a) || (b)) 388 #define IFF(a, b) (IMPLIES(a, b) && IMPLIES(b, a)) 389 390 /* --------------------------------------------------------------------- */ 391 392 /* 393 * Checks that the directory entry pointed by 'de' matches the name 'name' 394 * with a length of 'len'. 395 */ 396 #define TMPFS_DIRENT_MATCHES(de, name, len) \ 397 (de->td_namelen == (uint16_t)len && \ 398 memcmp((de)->td_name, (name), (de)->td_namelen) == 0) 399 400 /* --------------------------------------------------------------------- */ 401 402 /* 403 * Ensures that the node pointed by 'node' is a directory and that its 404 * contents are consistent with respect to directories. 405 */ 406 #define TMPFS_VALIDATE_DIR(node) \ 407 MPASS((node)->tn_type == VDIR); \ 408 MPASS((node)->tn_size % sizeof(struct tmpfs_dirent) == 0); \ 409 MPASS((node)->tn_dir.tn_readdir_lastp == NULL || \ 410 TMPFS_DIRCOOKIE((node)->tn_dir.tn_readdir_lastp) == (node)->tn_dir.tn_readdir_lastn); 411 412 /* --------------------------------------------------------------------- */ 413 414 /* 415 * Memory management stuff. 416 */ 417 418 /* Amount of memory pages to reserve for the system (e.g., to not use by 419 * tmpfs). 420 * XXX: Should this be tunable through sysctl, for instance? */ 421 #define TMPFS_PAGES_RESERVED (4 * 1024 * 1024 / PAGE_SIZE) 422 423 /* 424 * Returns information about the number of available memory pages, 425 * including physical and virtual ones. 426 * 427 * If 'total' is TRUE, the value returned is the total amount of memory 428 * pages configured for the system (either in use or free). 429 * If it is FALSE, the value returned is the amount of free memory pages. 430 * 431 * Remember to remove TMPFS_PAGES_RESERVED from the returned value to avoid 432 * excessive memory usage. 433 * 434 */ 435 static __inline size_t 436 tmpfs_mem_info(void) 437 { 438 size_t size; 439 440 size = swap_pager_avail + cnt.v_free_count + cnt.v_inactive_count; 441 size -= size > cnt.v_wire_count ? cnt.v_wire_count : size; 442 return size; 443 } 444 445 /* Returns the maximum size allowed for a tmpfs file system. This macro 446 * must be used instead of directly retrieving the value from tm_pages_max. 447 * The reason is that the size of a tmpfs file system is dynamic: it lets 448 * the user store files as long as there is enough free memory (including 449 * physical memory and swap space). Therefore, the amount of memory to be 450 * used is either the limit imposed by the user during mount time or the 451 * amount of available memory, whichever is lower. To avoid consuming all 452 * the memory for a given mount point, the system will always reserve a 453 * minimum of TMPFS_PAGES_RESERVED pages, which is also taken into account 454 * by this macro (see above). */ 455 static __inline size_t 456 TMPFS_PAGES_MAX(struct tmpfs_mount *tmp) 457 { 458 size_t freepages; 459 460 freepages = tmpfs_mem_info(); 461 freepages -= freepages < TMPFS_PAGES_RESERVED ? 462 freepages : TMPFS_PAGES_RESERVED; 463 464 return MIN(tmp->tm_pages_max, freepages + tmp->tm_pages_used); 465 } 466 467 /* Returns the available space for the given file system. */ 468 #define TMPFS_META_PAGES(tmp) (howmany((tmp)->tm_nodes_inuse * (sizeof(struct tmpfs_node) \ 469 + sizeof(struct tmpfs_dirent)), PAGE_SIZE)) 470 #define TMPFS_FILE_PAGES(tmp) ((tmp)->tm_pages_used) 471 472 #define TMPFS_PAGES_AVAIL(tmp) (TMPFS_PAGES_MAX(tmp) > \ 473 TMPFS_META_PAGES(tmp)+TMPFS_FILE_PAGES(tmp)? \ 474 TMPFS_PAGES_MAX(tmp) - TMPFS_META_PAGES(tmp) \ 475 - TMPFS_FILE_PAGES(tmp):0) 476 477 #endif 478 479 /* --------------------------------------------------------------------- */ 480 481 /* 482 * Macros/functions to convert from generic data structures to tmpfs 483 * specific ones. 484 */ 485 486 static inline 487 struct tmpfs_mount * 488 VFS_TO_TMPFS(struct mount *mp) 489 { 490 struct tmpfs_mount *tmp; 491 492 MPASS((mp) != NULL && (mp)->mnt_data != NULL); 493 tmp = (struct tmpfs_mount *)(mp)->mnt_data; 494 return tmp; 495 } 496 497 static inline 498 struct tmpfs_node * 499 VP_TO_TMPFS_NODE(struct vnode *vp) 500 { 501 struct tmpfs_node *node; 502 503 MPASS((vp) != NULL && (vp)->v_data != NULL); 504 node = (struct tmpfs_node *)vp->v_data; 505 return node; 506 } 507 508 static inline 509 struct tmpfs_node * 510 VP_TO_TMPFS_DIR(struct vnode *vp) 511 { 512 struct tmpfs_node *node; 513 514 node = VP_TO_TMPFS_NODE(vp); 515 TMPFS_VALIDATE_DIR(node); 516 return node; 517 } 518 519 #endif /* _FS_TMPFS_TMPFS_H_ */ 520