1 /* $NetBSD: tmpfs.h,v 1.13 2005/12/24 12:31:57 jmmv 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 40 #ifndef _FS_TMPFS_TMPFS_H_ 41 #define _FS_TMPFS_TMPFS_H_ 42 43 /* --------------------------------------------------------------------- 44 * KERNEL-SPECIFIC DEFINITIONS 45 * --------------------------------------------------------------------- */ 46 47 #if defined(_KERNEL) 48 49 #include <sys/dirent.h> 50 #include <sys/mount.h> 51 #include <sys/queue.h> 52 #include <sys/vnode.h> 53 54 #include <fs/tmpfs/tmpfs_pool.h> 55 56 /* --------------------------------------------------------------------- */ 57 58 /* 59 * Internal representation of a tmpfs directory entry. 60 */ 61 struct tmpfs_dirent { 62 TAILQ_ENTRY(tmpfs_dirent) td_entries; 63 64 /* Length of the name stored in this directory entry. This avoids 65 * the need to recalculate it every time the name is used. */ 66 uint16_t td_namelen; 67 68 /* The name of the entry, allocated from a string pool. This 69 * string is not required to be zero-terminated; therefore, the 70 * td_namelen field must always be used when accessing its value. */ 71 char * td_name; 72 73 /* Pointer to the node this entry refers to. */ 74 struct tmpfs_node * td_node; 75 }; 76 77 /* A directory in tmpfs holds a sorted list of directory entries, which in 78 * turn point to other files (which can be directories themselves). 79 * 80 * In tmpfs, this list is managed by a tail queue, whose head is defined by 81 * the struct tmpfs_dir type. 82 * 83 * It is imporant to notice that directories do not have entries for . and 84 * .. as other file systems do. These can be generated when requested 85 * based on information available by other means, such as the pointer to 86 * the node itself in the former case or the pointer to the parent directory 87 * in the latter case. This is done to simplify tmpfs's code and, more 88 * importantly, to remove redundancy. */ 89 TAILQ_HEAD(tmpfs_dir, tmpfs_dirent); 90 91 #define TMPFS_DIRCOOKIE(dirent) ((off_t)(uintptr_t)(dirent)) 92 #define TMPFS_DIRCOOKIE_DOT 0 93 #define TMPFS_DIRCOOKIE_DOTDOT 1 94 #define TMPFS_DIRCOOKIE_EOF 2 95 96 /* --------------------------------------------------------------------- */ 97 98 /* 99 * Internal representation of a tmpfs file system node. 100 * 101 * This structure is splitted in two parts: one holds attributes common 102 * to all file types and the other holds data that is only applicable to 103 * a particular type. The code must be careful to only access those 104 * attributes that are actually allowed by the node's type. 105 */ 106 struct tmpfs_node { 107 /* Doubly-linked list entry which links all existing nodes for a 108 * single file system. This is provided to ease the removal of 109 * all nodes during the unmount operation. */ 110 LIST_ENTRY(tmpfs_node) tn_entries; 111 112 /* The node's type. Any of 'VBLK', 'VCHR', 'VDIR', 'VFIFO', 113 * 'VLNK', 'VREG' and 'VSOCK' is allowed. The usage of vnode 114 * types instead of a custom enumeration is to make things simpler 115 * and faster, as we do not need to convert between two types. */ 116 enum vtype tn_type; 117 118 /* Node identifier. */ 119 ino_t tn_id; 120 121 /* Node's internal status. This is used by several file system 122 * operations to do modifications to the node in a delayed 123 * fashion. */ 124 int tn_status; 125 #define TMPFS_NODE_ACCESSED (1 << 1) 126 #define TMPFS_NODE_MODIFIED (1 << 2) 127 #define TMPFS_NODE_CHANGED (1 << 3) 128 129 /* The node size. It does not necessarily match the real amount 130 * of memory consumed by it. */ 131 off_t tn_size; 132 133 /* Generic node attributes. */ 134 uid_t tn_uid; 135 gid_t tn_gid; 136 mode_t tn_mode; 137 int tn_flags; 138 nlink_t tn_links; 139 struct timespec tn_atime; 140 struct timespec tn_mtime; 141 struct timespec tn_ctime; 142 struct timespec tn_birthtime; 143 unsigned long tn_gen; 144 145 /* Head of byte-level lock list (used by tmpfs_advlock). */ 146 struct lockf * tn_lockf; 147 148 /* As there is a single vnode for each active file within the 149 * system, care has to be taken to avoid allocating more than one 150 * vnode per file. In order to do this, a bidirectional association 151 * is kept between vnodes and nodes. 152 * 153 * Whenever a vnode is allocated, its v_data field is updated to 154 * point to the node it references. At the same time, the node's 155 * tn_vnode field is modified to point to the new vnode representing 156 * it. Further attempts to allocate a vnode for this same node will 157 * result in returning a new reference to the value stored in 158 * tn_vnode. 159 * 160 * May be NULL when the node is unused (that is, no vnode has been 161 * allocated for it or it has been reclaimed). */ 162 struct vnode * tn_vnode; 163 164 /* Pointer to the node returned by tmpfs_lookup() after doing a 165 * delete or a rename lookup; its value is only valid in these two 166 * situations. In case we were looking up . or .., it holds a null 167 * pointer. */ 168 struct tmpfs_dirent * tn_lookup_dirent; 169 170 union { 171 /* Valid when tn_type == VBLK || tn_type == VCHR. */ 172 struct { 173 dev_t tn_rdev; 174 }; 175 176 /* Valid when tn_type == VDIR. */ 177 struct { 178 /* Pointer to the parent directory. The root 179 * directory has a pointer to itself in this field; 180 * this property identifies the root node. */ 181 struct tmpfs_node * tn_parent; 182 183 /* Head of a tail-queue that links the contents of 184 * the directory together. See above for a 185 * description of its contents. */ 186 struct tmpfs_dir tn_dir; 187 188 /* Number and pointer of the first directory entry 189 * returned by the readdir operation if it were 190 * called again to continue reading data from the 191 * same directory as before. This is used to speed 192 * up reads of long directories, assuming that no 193 * more than one read is in progress at a given time. 194 * Otherwise, these values are discarded and a linear 195 * scan is performed from the beginning up to the 196 * point where readdir starts returning values. */ 197 off_t tn_readdir_lastn; 198 struct tmpfs_dirent * tn_readdir_lastp; 199 }; 200 201 /* Valid when tn_type == VLNK. */ 202 struct { 203 /* The link's target, allocated from a string pool. */ 204 char * tn_link; 205 }; 206 207 /* Valid when tn_type == VREG. */ 208 struct { 209 /* The contents of regular files stored in a tmpfs 210 * file system are represented by a single anonymous 211 * memory object (aobj, for short). The aobj provides 212 * direct access to any position within the file, 213 * because its contents are always mapped in a 214 * contiguous region of virtual memory. It is a task 215 * of the memory management subsystem (see uvm(9)) to 216 * issue the required page ins or page outs whenever 217 * a position within the file is accessed. */ 218 struct uvm_object * tn_aobj; 219 size_t tn_aobj_pages; 220 }; 221 }; 222 }; 223 LIST_HEAD(tmpfs_node_list, tmpfs_node); 224 225 /* --------------------------------------------------------------------- */ 226 227 /* 228 * Internal representation of a tmpfs mount point. 229 */ 230 struct tmpfs_mount { 231 /* Maximum number of memory pages available for use by the file 232 * system, set during mount time. This variable must never be 233 * used directly as it may be bigger that the current amount of 234 * free memory; in the extreme case, it will hold the SIZE_MAX 235 * value. Instead, use the TMPFS_PAGES_MAX macro. */ 236 size_t tm_pages_max; 237 238 /* Number of pages in use by the file system. Cannot be bigger 239 * than the value returned by TMPFS_PAGES_MAX in any case. */ 240 size_t tm_pages_used; 241 242 /* Pointer to the node representing the root directory of this 243 * file system. */ 244 struct tmpfs_node * tm_root; 245 246 /* Maximum number of possible nodes for this file system; set 247 * during mount time. We need a hard limit on the maximum number 248 * of nodes to avoid allocating too much of them; their objects 249 * cannot be released until the file system is unmounted. 250 * Otherwise, we could easily run out of memory by creating lots 251 * of empty files and then simply removing them. */ 252 ino_t tm_nodes_max; 253 254 /* Number of nodes currently allocated. This number only grows. 255 * When it reaches tm_nodes_max, no more new nodes can be allocated. 256 * Of course, the old, unused ones can be reused. */ 257 ino_t tm_nodes_last; 258 259 /* Nodes are organized in two different lists. The used list 260 * contains all nodes that are currently used by the file system; 261 * i.e., they refer to existing files. The available list contains 262 * all nodes that are currently available for use by new files. 263 * Nodes must be kept in this list (instead of deleting them) 264 * because we need to keep track of their generation number (tn_gen 265 * field). 266 * 267 * Note that nodes are lazily allocated: if the available list is 268 * empty and we have enough space to create more nodes, they will be 269 * created and inserted in the used list. Once these are released, 270 * they will go into the available list, remaining alive until the 271 * file system is unmounted. */ 272 struct tmpfs_node_list tm_nodes_used; 273 struct tmpfs_node_list tm_nodes_avail; 274 275 /* Pools used to store file system meta data. These are not shared 276 * across several instances of tmpfs for the reasons described in 277 * tmpfs_pool.c. */ 278 struct tmpfs_pool tm_dirent_pool; 279 struct tmpfs_pool tm_node_pool; 280 struct tmpfs_str_pool tm_str_pool; 281 }; 282 283 /* --------------------------------------------------------------------- */ 284 285 /* 286 * This structure maps a file identifier to a tmpfs node. Used by the 287 * NFS code. 288 */ 289 struct tmpfs_fid { 290 uint16_t tf_len; 291 uint16_t tf_pad; 292 ino_t tf_id; 293 unsigned long tf_gen; 294 }; 295 296 /* --------------------------------------------------------------------- */ 297 298 /* 299 * Prototypes for tmpfs_subr.c. 300 */ 301 302 int tmpfs_alloc_node(struct tmpfs_mount *, enum vtype, 303 uid_t uid, gid_t gid, mode_t mode, struct tmpfs_node *, 304 char *, dev_t, struct proc *, struct tmpfs_node **); 305 void tmpfs_free_node(struct tmpfs_mount *, struct tmpfs_node *); 306 int tmpfs_alloc_dirent(struct tmpfs_mount *, struct tmpfs_node *, 307 const char *, uint16_t, struct tmpfs_dirent **); 308 void tmpfs_free_dirent(struct tmpfs_mount *, struct tmpfs_dirent *, 309 boolean_t); 310 int tmpfs_alloc_vp(struct mount *, struct tmpfs_node *, struct vnode **); 311 void tmpfs_free_vp(struct vnode *); 312 int tmpfs_alloc_file(struct vnode *, struct vnode **, struct vattr *, 313 struct componentname *, char *); 314 void tmpfs_dir_attach(struct vnode *, struct tmpfs_dirent *); 315 void tmpfs_dir_detach(struct vnode *, struct tmpfs_dirent *); 316 struct tmpfs_dirent * tmpfs_dir_lookup(struct tmpfs_node *node, 317 struct componentname *cnp); 318 int tmpfs_dir_getdotdent(struct tmpfs_node *, struct uio *); 319 int tmpfs_dir_getdotdotdent(struct tmpfs_node *, struct uio *); 320 struct tmpfs_dirent * tmpfs_dir_lookupbycookie(struct tmpfs_node *, off_t); 321 int tmpfs_dir_getdents(struct tmpfs_node *, struct uio *, off_t *); 322 int tmpfs_reg_resize(struct vnode *, off_t); 323 size_t tmpfs_mem_info(boolean_t); 324 int tmpfs_chflags(struct vnode *, int, struct ucred *, struct proc *); 325 int tmpfs_chmod(struct vnode *, mode_t, struct ucred *, struct proc *); 326 int tmpfs_chown(struct vnode *, uid_t, gid_t, struct ucred *, 327 struct proc *); 328 int tmpfs_chsize(struct vnode *, u_quad_t, struct ucred *, struct proc *); 329 int tmpfs_chtimes(struct vnode *, struct timespec *, struct timespec *, 330 int, struct ucred *, struct lwp *); 331 void tmpfs_itimes(struct vnode *, const struct timespec *, 332 const struct timespec *); 333 334 void tmpfs_update(struct vnode *, const struct timespec *, 335 const struct timespec *, int); 336 int tmpfs_truncate(struct vnode *, off_t); 337 338 /* --------------------------------------------------------------------- */ 339 340 /* 341 * Convenience macros to simplify some logical expressions. 342 */ 343 #define IMPLIES(a, b) (!(a) || (b)) 344 #define IFF(a, b) (IMPLIES(a, b) && IMPLIES(b, a)) 345 346 /* --------------------------------------------------------------------- */ 347 348 /* 349 * Checks that the directory entry pointed by 'de' matches the name 'name' 350 * with a length of 'len'. 351 */ 352 #define TMPFS_DIRENT_MATCHES(de, name, len) \ 353 (de->td_namelen == (uint16_t)len && \ 354 memcmp((de)->td_name, (name), (de)->td_namelen) == 0) 355 356 /* --------------------------------------------------------------------- */ 357 358 /* 359 * Ensures that the node pointed by 'node' is a directory and that its 360 * contents are consistent with respect to directories. 361 */ 362 #define TMPFS_VALIDATE_DIR(node) \ 363 KASSERT((node)->tn_type == VDIR); \ 364 KASSERT((node)->tn_size % sizeof(struct tmpfs_dirent) == 0); \ 365 KASSERT((node)->tn_readdir_lastp == NULL || \ 366 TMPFS_DIRCOOKIE((node)->tn_readdir_lastp) == (node)->tn_readdir_lastn); 367 368 /* --------------------------------------------------------------------- */ 369 370 /* 371 * Memory management stuff. 372 */ 373 374 /* Amount of memory pages to reserve for the system (e.g., to not use by 375 * tmpfs). 376 * XXX: Should this be tunable through sysctl, for instance? */ 377 #define TMPFS_PAGES_RESERVED (4 * 1024 * 1024 / PAGE_SIZE) 378 379 /* Returns the maximum size allowed for a tmpfs file system. This macro 380 * must be used instead of directly retrieving the value from tm_pages_max. 381 * The reason is that the size of a tmpfs file system is dynamic: it lets 382 * the user store files as long as there is enough free memory (including 383 * physical memory and swap space). Therefore, the amount of memory to be 384 * used is either the limit imposed by the user during mount time or the 385 * amount of available memory, whichever is lower. To avoid consuming all 386 * the memory for a given mount point, the system will always reserve a 387 * minimum of TMPFS_PAGES_RESERVED pages, which is also taken into account 388 * by this macro (see above). */ 389 static inline size_t 390 TMPFS_PAGES_MAX(struct tmpfs_mount *tmp) 391 { 392 size_t freepages; 393 394 freepages = tmpfs_mem_info(FALSE); 395 if (freepages < TMPFS_PAGES_RESERVED) 396 freepages = 0; 397 else 398 freepages -= TMPFS_PAGES_RESERVED; 399 400 return MIN(tmp->tm_pages_max, freepages + tmp->tm_pages_used); 401 } 402 403 /* Returns the available space for the given file system. */ 404 #define TMPFS_PAGES_AVAIL(tmp) (TMPFS_PAGES_MAX(tmp) - (tmp)->tm_pages_used) 405 406 /* --------------------------------------------------------------------- */ 407 408 /* 409 * Macros/functions to convert from generic data structures to tmpfs 410 * specific ones. 411 */ 412 413 static inline 414 struct tmpfs_mount * 415 VFS_TO_TMPFS(struct mount *mp) 416 { 417 struct tmpfs_mount *tmp; 418 419 KASSERT((mp) != NULL && (mp)->mnt_data != NULL); 420 tmp = (struct tmpfs_mount *)(mp)->mnt_data; 421 return tmp; 422 } 423 424 static inline 425 struct tmpfs_node * 426 VP_TO_TMPFS_NODE(struct vnode *vp) 427 { 428 struct tmpfs_node *node; 429 430 KASSERT((vp) != NULL && (vp)->v_data != NULL); 431 node = (struct tmpfs_node *)vp->v_data; 432 return node; 433 } 434 435 static inline 436 struct tmpfs_node * 437 VP_TO_TMPFS_DIR(struct vnode *vp) 438 { 439 struct tmpfs_node *node; 440 441 node = VP_TO_TMPFS_NODE(vp); 442 TMPFS_VALIDATE_DIR(node); 443 return node; 444 } 445 446 #endif /* _KERNEL */ 447 448 /* --------------------------------------------------------------------- 449 * USER AND KERNEL DEFINITIONS 450 * --------------------------------------------------------------------- */ 451 452 /* 453 * This structure is used to communicate mount parameters between userland 454 * and kernel space. 455 */ 456 #define TMPFS_ARGS_VERSION 1 457 struct tmpfs_args { 458 int ta_version; 459 460 /* Size counters. */ 461 ino_t ta_nodes_max; 462 off_t ta_size_max; 463 464 /* Root node attributes. */ 465 uid_t ta_root_uid; 466 gid_t ta_root_gid; 467 mode_t ta_root_mode; 468 }; 469 #endif /* _FS_TMPFS_TMPFS_H_ */ 470