1 /* $NetBSD: tmpfs.h,v 1.16 2006/02/16 20:17:19 perry Exp $ */ 2 3 /* 4 * Copyright (c) 2005, 2006 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 40 #ifndef _FS_TMPFS_TMPFS_H_ 41 #define _FS_TMPFS_TMPFS_H_ 42 43 /* --------------------------------------------------------------------- 44 * KERNEL-SPECIFIC DEFINITIONS 45 * --------------------------------------------------------------------- */ 46 #include <sys/dirent.h> 47 #include <sys/mount.h> 48 #include <sys/queue.h> 49 #include <sys/vnode.h> 50 51 #include <fs/tmpfs/tmpfs_pool.h> 52 53 /* --------------------------------------------------------------------- */ 54 55 /* 56 * Internal representation of a tmpfs directory entry. 57 */ 58 struct tmpfs_dirent { 59 TAILQ_ENTRY(tmpfs_dirent) td_entries; 60 61 /* Length of the name stored in this directory entry. This avoids 62 * the need to recalculate it every time the name is used. */ 63 uint16_t td_namelen; 64 65 /* The name of the entry, allocated from a string pool. This 66 * string is not required to be zero-terminated; therefore, the 67 * td_namelen field must always be used when accessing its value. */ 68 char * td_name; 69 70 /* Pointer to the node this entry refers to. */ 71 struct tmpfs_node * td_node; 72 }; 73 74 /* A directory in tmpfs holds a sorted list of directory entries, which in 75 * turn point to other files (which can be directories themselves). 76 * 77 * In tmpfs, this list is managed by a tail queue, whose head is defined by 78 * the struct tmpfs_dir type. 79 * 80 * It is imporant to notice that directories do not have entries for . and 81 * .. as other file systems do. These can be generated when requested 82 * based on information available by other means, such as the pointer to 83 * the node itself in the former case or the pointer to the parent directory 84 * in the latter case. This is done to simplify tmpfs's code and, more 85 * importantly, to remove redundancy. */ 86 TAILQ_HEAD(tmpfs_dir, tmpfs_dirent); 87 88 #define TMPFS_DIRCOOKIE(dirent) ((off_t)(uintptr_t)(dirent)) 89 #define TMPFS_DIRCOOKIE_DOT 0 90 #define TMPFS_DIRCOOKIE_DOTDOT 1 91 #define TMPFS_DIRCOOKIE_EOF 2 92 93 /* --------------------------------------------------------------------- */ 94 95 /* 96 * Internal representation of a tmpfs file system node. 97 * 98 * This structure is splitted in two parts: one holds attributes common 99 * to all file types and the other holds data that is only applicable to 100 * a particular type. The code must be careful to only access those 101 * attributes that are actually allowed by the node's type. 102 */ 103 struct tmpfs_node { 104 /* Doubly-linked list entry which links all existing nodes for a 105 * single file system. This is provided to ease the removal of 106 * all nodes during the unmount operation. */ 107 LIST_ENTRY(tmpfs_node) tn_entries; 108 109 /* The node's type. Any of 'VBLK', 'VCHR', 'VDIR', 'VFIFO', 110 * 'VLNK', 'VREG' and 'VSOCK' is allowed. The usage of vnode 111 * types instead of a custom enumeration is to make things simpler 112 * and faster, as we do not need to convert between two types. */ 113 enum vtype tn_type; 114 115 /* Node identifier. */ 116 ino_t tn_id; 117 118 /* Node's internal status. This is used by several file system 119 * operations to do modifications to the node in a delayed 120 * fashion. */ 121 int tn_status; 122 #define TMPFS_NODE_ACCESSED (1 << 1) 123 #define TMPFS_NODE_MODIFIED (1 << 2) 124 #define TMPFS_NODE_CHANGED (1 << 3) 125 126 /* The node size. It does not necessarily match the real amount 127 * of memory consumed by it. */ 128 off_t tn_size; 129 130 /* Generic node attributes. */ 131 uid_t tn_uid; 132 gid_t tn_gid; 133 mode_t tn_mode; 134 int tn_flags; 135 nlink_t tn_links; 136 struct timespec tn_atime; 137 struct timespec tn_mtime; 138 struct timespec tn_ctime; 139 struct timespec tn_birthtime; 140 unsigned long tn_gen; 141 142 /* Head of byte-level lock list (used by tmpfs_advlock). */ 143 struct lockf * tn_lockf; 144 145 /* As there is a single vnode for each active file within the 146 * system, care has to be taken to avoid allocating more than one 147 * vnode per file. In order to do this, a bidirectional association 148 * is kept between vnodes and nodes. 149 * 150 * Whenever a vnode is allocated, its v_data field is updated to 151 * point to the node it references. At the same time, the node's 152 * tn_vnode field is modified to point to the new vnode representing 153 * it. Further attempts to allocate a vnode for this same node will 154 * result in returning a new reference to the value stored in 155 * tn_vnode. 156 * 157 * May be NULL when the node is unused (that is, no vnode has been 158 * allocated for it or it has been reclaimed). */ 159 struct vnode * tn_vnode; 160 161 /* Pointer to the node returned by tmpfs_lookup() after doing a 162 * delete or a rename lookup; its value is only valid in these two 163 * situations. In case we were looking up . or .., it holds a null 164 * pointer. */ 165 struct tmpfs_dirent * tn_lookup_dirent; 166 167 union { 168 /* Valid when tn_type == VBLK || tn_type == VCHR. */ 169 struct { 170 dev_t tn_rdev; 171 } tn_dev; 172 173 /* Valid when tn_type == VDIR. */ 174 struct { 175 /* Pointer to the parent directory. The root 176 * directory has a pointer to itself in this field; 177 * this property identifies the root node. */ 178 struct tmpfs_node * tn_parent; 179 180 /* Head of a tail-queue that links the contents of 181 * the directory together. See above for a 182 * description of its contents. */ 183 struct tmpfs_dir tn_dir; 184 185 /* Number and pointer of the first directory entry 186 * returned by the readdir operation if it were 187 * called again to continue reading data from the 188 * same directory as before. This is used to speed 189 * up reads of long directories, assuming that no 190 * more than one read is in progress at a given time. 191 * Otherwise, these values are discarded and a linear 192 * scan is performed from the beginning up to the 193 * point where readdir starts returning values. */ 194 off_t tn_readdir_lastn; 195 struct tmpfs_dirent * tn_readdir_lastp; 196 } tn_dir; 197 198 /* Valid when tn_type == VLNK. */ 199 struct tn_lnk { 200 /* The link's target, allocated from a string pool. */ 201 char * tn_link; 202 } tn_lnk; 203 204 /* Valid when tn_type == VREG. */ 205 struct tn_reg { 206 /* The contents of regular files stored in a tmpfs 207 * file system are represented by a single anonymous 208 * memory object (aobj, for short). The aobj provides 209 * direct access to any position within the file, 210 * because its contents are always mapped in a 211 * contiguous region of virtual memory. It is a task 212 * of the memory management subsystem (see uvm(9)) to 213 * issue the required page ins or page outs whenever 214 * a position within the file is accessed. */ 215 struct uvm_object * tn_aobj; 216 size_t tn_aobj_pages; 217 } tn_reg; 218 } tn_spec; 219 }; 220 LIST_HEAD(tmpfs_node_list, tmpfs_node); 221 222 /* --------------------------------------------------------------------- */ 223 224 /* 225 * Internal representation of a tmpfs mount point. 226 */ 227 struct tmpfs_mount { 228 /* Maximum number of memory pages available for use by the file 229 * system, set during mount time. This variable must never be 230 * used directly as it may be bigger that the current amount of 231 * free memory; in the extreme case, it will hold the SIZE_MAX 232 * value. Instead, use the TMPFS_PAGES_MAX macro. */ 233 size_t tm_pages_max; 234 235 /* Number of pages in use by the file system. Cannot be bigger 236 * than the value returned by TMPFS_PAGES_MAX in any case. */ 237 size_t tm_pages_used; 238 239 /* Pointer to the node representing the root directory of this 240 * file system. */ 241 struct tmpfs_node * tm_root; 242 243 /* Maximum number of possible nodes for this file system; set 244 * during mount time. We need a hard limit on the maximum number 245 * of nodes to avoid allocating too much of them; their objects 246 * cannot be released until the file system is unmounted. 247 * Otherwise, we could easily run out of memory by creating lots 248 * of empty files and then simply removing them. */ 249 ino_t tm_nodes_max; 250 251 /* Number of nodes currently allocated. This number only grows. 252 * When it reaches tm_nodes_max, no more new nodes can be allocated. 253 * Of course, the old, unused ones can be reused. */ 254 ino_t tm_nodes_last; 255 256 /* Nodes are organized in two different lists. The used list 257 * contains all nodes that are currently used by the file system; 258 * i.e., they refer to existing files. The available list contains 259 * all nodes that are currently available for use by new files. 260 * Nodes must be kept in this list (instead of deleting them) 261 * because we need to keep track of their generation number (tn_gen 262 * field). 263 * 264 * Note that nodes are lazily allocated: if the available list is 265 * empty and we have enough space to create more nodes, they will be 266 * created and inserted in the used list. Once these are released, 267 * they will go into the available list, remaining alive until the 268 * file system is unmounted. */ 269 struct tmpfs_node_list tm_nodes_used; 270 struct tmpfs_node_list tm_nodes_avail; 271 272 /* Pools used to store file system meta data. These are not shared 273 * across several instances of tmpfs for the reasons described in 274 * tmpfs_pool.c. */ 275 struct tmpfs_pool tm_dirent_pool; 276 struct tmpfs_pool tm_node_pool; 277 struct tmpfs_str_pool tm_str_pool; 278 }; 279 280 /* --------------------------------------------------------------------- */ 281 282 /* 283 * This structure maps a file identifier to a tmpfs node. Used by the 284 * NFS code. 285 */ 286 struct tmpfs_fid { 287 uint16_t tf_len; 288 uint16_t tf_pad; 289 ino_t tf_id; 290 unsigned long tf_gen; 291 }; 292 293 /* --------------------------------------------------------------------- */ 294 295 #ifdef _KERNEL 296 /* 297 * Prototypes for tmpfs_subr.c. 298 */ 299 300 int tmpfs_alloc_node(struct tmpfs_mount *, enum vtype, 301 uid_t uid, gid_t gid, mode_t mode, struct tmpfs_node *, 302 char *, dev_t, struct proc *, struct tmpfs_node **); 303 void tmpfs_free_node(struct tmpfs_mount *, struct tmpfs_node *); 304 int tmpfs_alloc_dirent(struct tmpfs_mount *, struct tmpfs_node *, 305 const char *, uint16_t, struct tmpfs_dirent **); 306 void tmpfs_free_dirent(struct tmpfs_mount *, struct tmpfs_dirent *, 307 boolean_t); 308 int tmpfs_alloc_vp(struct mount *, struct tmpfs_node *, struct vnode **); 309 void tmpfs_free_vp(struct vnode *); 310 int tmpfs_alloc_file(struct vnode *, struct vnode **, struct vattr *, 311 struct componentname *, char *); 312 void tmpfs_dir_attach(struct vnode *, struct tmpfs_dirent *); 313 void tmpfs_dir_detach(struct vnode *, struct tmpfs_dirent *); 314 struct tmpfs_dirent * tmpfs_dir_lookup(struct tmpfs_node *node, 315 struct componentname *cnp); 316 int tmpfs_dir_getdotdent(struct tmpfs_node *, struct uio *); 317 int tmpfs_dir_getdotdotdent(struct tmpfs_node *, struct uio *); 318 struct tmpfs_dirent * tmpfs_dir_lookupbycookie(struct tmpfs_node *, off_t); 319 int tmpfs_dir_getdents(struct tmpfs_node *, struct uio *, off_t *); 320 int tmpfs_reg_resize(struct vnode *, off_t); 321 size_t tmpfs_mem_info(boolean_t); 322 int tmpfs_chflags(struct vnode *, int, struct ucred *, struct proc *); 323 int tmpfs_chmod(struct vnode *, mode_t, struct ucred *, struct proc *); 324 int tmpfs_chown(struct vnode *, uid_t, gid_t, struct ucred *, 325 struct proc *); 326 int tmpfs_chsize(struct vnode *, u_quad_t, struct ucred *, struct proc *); 327 int tmpfs_chtimes(struct vnode *, struct timespec *, struct timespec *, 328 int, struct ucred *, struct lwp *); 329 void tmpfs_itimes(struct vnode *, const struct timespec *, 330 const struct timespec *); 331 332 void tmpfs_update(struct vnode *, const struct timespec *, 333 const struct timespec *, int); 334 int tmpfs_truncate(struct vnode *, off_t); 335 336 /* --------------------------------------------------------------------- */ 337 338 /* 339 * Convenience macros to simplify some logical expressions. 340 */ 341 #define IMPLIES(a, b) (!(a) || (b)) 342 #define IFF(a, b) (IMPLIES(a, b) && IMPLIES(b, a)) 343 344 /* --------------------------------------------------------------------- */ 345 346 /* 347 * Checks that the directory entry pointed by 'de' matches the name 'name' 348 * with a length of 'len'. 349 */ 350 #define TMPFS_DIRENT_MATCHES(de, name, len) \ 351 (de->td_namelen == (uint16_t)len && \ 352 memcmp((de)->td_name, (name), (de)->td_namelen) == 0) 353 354 /* --------------------------------------------------------------------- */ 355 356 /* 357 * Ensures that the node pointed by 'node' is a directory and that its 358 * contents are consistent with respect to directories. 359 */ 360 #define TMPFS_VALIDATE_DIR(node) \ 361 KASSERT((node)->tn_type == VDIR); \ 362 KASSERT((node)->tn_size % sizeof(struct tmpfs_dirent) == 0); \ 363 KASSERT((node)->tn_spec.tn_dir.tn_readdir_lastp == NULL || \ 364 TMPFS_DIRCOOKIE((node)->tn_spec.tn_dir.tn_readdir_lastp) == \ 365 (node)->tn_spec.tn_dir.tn_readdir_lastn); 366 367 /* --------------------------------------------------------------------- */ 368 369 /* 370 * Memory management stuff. 371 */ 372 373 /* Amount of memory pages to reserve for the system (e.g., to not use by 374 * tmpfs). 375 * XXX: Should this be tunable through sysctl, for instance? */ 376 #define TMPFS_PAGES_RESERVED (4 * 1024 * 1024 / PAGE_SIZE) 377 378 /* Returns the maximum size allowed for a tmpfs file system. This macro 379 * must be used instead of directly retrieving the value from tm_pages_max. 380 * The reason is that the size of a tmpfs file system is dynamic: it lets 381 * the user store files as long as there is enough free memory (including 382 * physical memory and swap space). Therefore, the amount of memory to be 383 * used is either the limit imposed by the user during mount time or the 384 * amount of available memory, whichever is lower. To avoid consuming all 385 * the memory for a given mount point, the system will always reserve a 386 * minimum of TMPFS_PAGES_RESERVED pages, which is also taken into account 387 * by this macro (see above). */ 388 static __inline size_t 389 TMPFS_PAGES_MAX(struct tmpfs_mount *tmp) 390 { 391 size_t freepages; 392 393 freepages = tmpfs_mem_info(FALSE); 394 if (freepages < TMPFS_PAGES_RESERVED) 395 freepages = 0; 396 else 397 freepages -= TMPFS_PAGES_RESERVED; 398 399 return MIN(tmp->tm_pages_max, freepages + tmp->tm_pages_used); 400 } 401 402 /* Returns the available space for the given file system. */ 403 #define TMPFS_PAGES_AVAIL(tmp) (TMPFS_PAGES_MAX(tmp) - (tmp)->tm_pages_used) 404 405 #endif 406 407 /* --------------------------------------------------------------------- */ 408 409 /* 410 * Macros/functions to convert from generic data structures to tmpfs 411 * specific ones. 412 */ 413 414 static __inline 415 struct tmpfs_mount * 416 VFS_TO_TMPFS(struct mount *mp) 417 { 418 struct tmpfs_mount *tmp; 419 420 #ifdef KASSERT 421 KASSERT((mp) != NULL && (mp)->mnt_data != NULL); 422 #endif 423 tmp = (struct tmpfs_mount *)(mp)->mnt_data; 424 return tmp; 425 } 426 427 static __inline 428 struct tmpfs_node * 429 VP_TO_TMPFS_NODE(struct vnode *vp) 430 { 431 struct tmpfs_node *node; 432 433 #ifdef KASSERT 434 KASSERT((vp) != NULL && (vp)->v_data != NULL); 435 #endif 436 node = (struct tmpfs_node *)vp->v_data; 437 return node; 438 } 439 440 static __inline 441 struct tmpfs_node * 442 VP_TO_TMPFS_DIR(struct vnode *vp) 443 { 444 struct tmpfs_node *node; 445 446 node = VP_TO_TMPFS_NODE(vp); 447 #ifdef KASSERT 448 TMPFS_VALIDATE_DIR(node); 449 #endif 450 return node; 451 } 452 453 /* --------------------------------------------------------------------- 454 * USER AND KERNEL DEFINITIONS 455 * --------------------------------------------------------------------- */ 456 457 /* 458 * This structure is used to communicate mount parameters between userland 459 * and kernel space. 460 */ 461 #define TMPFS_ARGS_VERSION 1 462 struct tmpfs_args { 463 int ta_version; 464 465 /* Size counters. */ 466 ino_t ta_nodes_max; 467 off_t ta_size_max; 468 469 /* Root node attributes. */ 470 uid_t ta_root_uid; 471 gid_t ta_root_gid; 472 mode_t ta_root_mode; 473 }; 474 #endif /* _FS_TMPFS_TMPFS_H_ */ 475