tmpfs.h revision 312809
1/* $NetBSD: tmpfs.h,v 1.26 2007/02/22 06:37:00 thorpej 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 * 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 * $FreeBSD: stable/10/sys/fs/tmpfs/tmpfs.h 312809 2017-01-26 11:04:27Z kib $ 33 */ 34 35#ifndef _FS_TMPFS_TMPFS_H_ 36#define _FS_TMPFS_TMPFS_H_ 37 38#include <sys/dirent.h> 39#include <sys/mount.h> 40#include <sys/queue.h> 41#include <sys/vnode.h> 42#include <sys/file.h> 43#include <sys/lock.h> 44#include <sys/mutex.h> 45 46#include <sys/malloc.h> 47#include <sys/systm.h> 48#include <sys/tree.h> 49#include <sys/vmmeter.h> 50#include <vm/swap_pager.h> 51 52MALLOC_DECLARE(M_TMPFSMNT); 53MALLOC_DECLARE(M_TMPFSNAME); 54 55/* 56 * Internal representation of a tmpfs directory entry. 57 */ 58 59LIST_HEAD(tmpfs_dir_duphead, tmpfs_dirent); 60 61struct tmpfs_dirent { 62 /* 63 * Depending on td_cookie flag entry can be of 3 types: 64 * - regular -- no hash collisions, stored in RB-Tree 65 * - duphead -- synthetic linked list head for dup entries 66 * - dup -- stored in linked list instead of RB-Tree 67 */ 68 union { 69 /* regular and duphead entry types */ 70 RB_ENTRY(tmpfs_dirent) td_entries; 71 72 /* dup entry type */ 73 struct { 74 LIST_ENTRY(tmpfs_dirent) entries; 75 LIST_ENTRY(tmpfs_dirent) index_entries; 76 } td_dup; 77 } uh; 78 79 uint32_t td_cookie; 80 uint32_t td_hash; 81 u_int td_namelen; 82 83 /* 84 * Pointer to the node this entry refers to. In case this field 85 * is NULL, the node is a whiteout. 86 */ 87 struct tmpfs_node * td_node; 88 89 union { 90 /* 91 * The name of the entry, allocated from a string pool. This 92 * string is not required to be zero-terminated. 93 */ 94 char * td_name; /* regular, dup */ 95 struct tmpfs_dir_duphead td_duphead; /* duphead */ 96 } ud; 97}; 98 99/* 100 * A directory in tmpfs holds a collection of directory entries, which 101 * in turn point to other files (which can be directories themselves). 102 * 103 * In tmpfs, this collection is managed by a RB-Tree, whose head is 104 * defined by the struct tmpfs_dir type. 105 * 106 * It is important to notice that directories do not have entries for . and 107 * .. as other file systems do. These can be generated when requested 108 * based on information available by other means, such as the pointer to 109 * the node itself in the former case or the pointer to the parent directory 110 * in the latter case. This is done to simplify tmpfs's code and, more 111 * importantly, to remove redundancy. 112 */ 113RB_HEAD(tmpfs_dir, tmpfs_dirent); 114 115/* 116 * Each entry in a directory has a cookie that identifies it. Cookies 117 * supersede offsets within directories because, given how tmpfs stores 118 * directories in memory, there is no such thing as an offset. 119 * 120 * The '.', '..' and the end of directory markers have fixed cookies which 121 * cannot collide with the cookies generated by other entries. The cookies 122 * for the other entries are generated based on the file name hash value or 123 * unique number in case of name hash collision. 124 * 125 * To preserve compatibility cookies are limited to 31 bits. 126 */ 127 128#define TMPFS_DIRCOOKIE_DOT 0 129#define TMPFS_DIRCOOKIE_DOTDOT 1 130#define TMPFS_DIRCOOKIE_EOF 2 131#define TMPFS_DIRCOOKIE_MASK ((off_t)0x3fffffffU) 132#define TMPFS_DIRCOOKIE_MIN ((off_t)0x00000004U) 133#define TMPFS_DIRCOOKIE_DUP ((off_t)0x40000000U) 134#define TMPFS_DIRCOOKIE_DUPHEAD ((off_t)0x80000000U) 135#define TMPFS_DIRCOOKIE_DUP_MIN TMPFS_DIRCOOKIE_DUP 136#define TMPFS_DIRCOOKIE_DUP_MAX \ 137 (TMPFS_DIRCOOKIE_DUP | TMPFS_DIRCOOKIE_MASK) 138 139/* 140 * Internal representation of a tmpfs file system node. 141 * 142 * This structure is splitted in two parts: one holds attributes common 143 * to all file types and the other holds data that is only applicable to 144 * a particular type. The code must be careful to only access those 145 * attributes that are actually allowed by the node's type. 146 * 147 * Below is the key of locks used to protected the fields in the following 148 * structures. 149 * (v) vnode lock in exclusive mode 150 * (vi) vnode lock in exclusive mode, or vnode lock in shared vnode and 151 * tn_interlock 152 * (i) tn_interlock 153 * (m) tmpfs_mount tm_allnode_lock 154 * (c) stable after creation 155 */ 156struct tmpfs_node { 157 /* 158 * Doubly-linked list entry which links all existing nodes for 159 * a single file system. This is provided to ease the removal 160 * of all nodes during the unmount operation, and to support 161 * the implementation of VOP_VNTOCNP(). 162 */ 163 LIST_ENTRY(tmpfs_node) tn_entries; /* (m) */ 164 165 /* 166 * The node's type. Any of 'VBLK', 'VCHR', 'VDIR', 'VFIFO', 167 * 'VLNK', 'VREG' and 'VSOCK' is allowed. The usage of vnode 168 * types instead of a custom enumeration is to make things simpler 169 * and faster, as we do not need to convert between two types. 170 */ 171 enum vtype tn_type; /* (c) */ 172 173 /* Node identifier. */ 174 ino_t tn_id; /* (c) */ 175 176 /* 177 * Node's internal status. This is used by several file system 178 * operations to do modifications to the node in a delayed 179 * fashion. 180 */ 181 int tn_status; /* (vi) */ 182#define TMPFS_NODE_ACCESSED (1 << 1) 183#define TMPFS_NODE_MODIFIED (1 << 2) 184#define TMPFS_NODE_CHANGED (1 << 3) 185 186 /* 187 * The node size. It does not necessarily match the real amount 188 * of memory consumed by it. 189 */ 190 off_t tn_size; /* (v) */ 191 192 /* Generic node attributes. */ 193 uid_t tn_uid; /* (v) */ 194 gid_t tn_gid; /* (v) */ 195 mode_t tn_mode; /* (v) */ 196 u_long tn_flags; /* (v) */ 197 nlink_t tn_links; /* (v) */ 198 struct timespec tn_atime; /* (vi) */ 199 struct timespec tn_mtime; /* (vi) */ 200 struct timespec tn_ctime; /* (vi) */ 201 struct timespec tn_birthtime; /* (v) */ 202 unsigned long tn_gen; /* (c) */ 203 204 /* 205 * As there is a single vnode for each active file within the 206 * system, care has to be taken to avoid allocating more than one 207 * vnode per file. In order to do this, a bidirectional association 208 * is kept between vnodes and nodes. 209 * 210 * Whenever a vnode is allocated, its v_data field is updated to 211 * point to the node it references. At the same time, the node's 212 * tn_vnode field is modified to point to the new vnode representing 213 * it. Further attempts to allocate a vnode for this same node will 214 * result in returning a new reference to the value stored in 215 * tn_vnode. 216 * 217 * May be NULL when the node is unused (that is, no vnode has been 218 * allocated for it or it has been reclaimed). 219 */ 220 struct vnode * tn_vnode; /* (i) */ 221 222 /* 223 * Interlock to protect tn_vpstate, and tn_status under shared 224 * vnode lock. 225 */ 226 struct mtx tn_interlock; 227 228 /* 229 * Identify if current node has vnode assiocate with 230 * or allocating vnode. 231 */ 232 int tn_vpstate; /* (i) */ 233 234 /* misc data field for different tn_type node */ 235 union { 236 /* Valid when tn_type == VBLK || tn_type == VCHR. */ 237 dev_t tn_rdev; /* (c) */ 238 239 /* Valid when tn_type == VDIR. */ 240 struct tn_dir { 241 /* 242 * Pointer to the parent directory. The root 243 * directory has a pointer to itself in this field; 244 * this property identifies the root node. 245 */ 246 struct tmpfs_node * tn_parent; 247 248 /* 249 * Head of a tree that links the contents of 250 * the directory together. 251 */ 252 struct tmpfs_dir tn_dirhead; 253 254 /* 255 * Head of a list the contains fake directory entries 256 * heads, i.e. entries with TMPFS_DIRCOOKIE_DUPHEAD 257 * flag. 258 */ 259 struct tmpfs_dir_duphead tn_dupindex; 260 261 /* 262 * Number and pointer of the first directory entry 263 * returned by the readdir operation if it were 264 * called again to continue reading data from the 265 * same directory as before. This is used to speed 266 * up reads of long directories, assuming that no 267 * more than one read is in progress at a given time. 268 * Otherwise, these values are discarded. 269 */ 270 off_t tn_readdir_lastn; 271 struct tmpfs_dirent * tn_readdir_lastp; 272 } tn_dir; 273 274 /* Valid when tn_type == VLNK. */ 275 /* The link's target, allocated from a string pool. */ 276 char * tn_link; /* (c) */ 277 278 /* Valid when tn_type == VREG. */ 279 struct tn_reg { 280 /* 281 * The contents of regular files stored in a 282 * tmpfs file system are represented by a 283 * single anonymous memory object (aobj, for 284 * short). The aobj provides direct access to 285 * any position within the file. It is a task 286 * of the memory management subsystem to issue 287 * the required page ins or page outs whenever 288 * a position within the file is accessed. 289 */ 290 vm_object_t tn_aobj; /* (c) */ 291 } tn_reg; 292 } tn_spec; /* (v) */ 293}; 294LIST_HEAD(tmpfs_node_list, tmpfs_node); 295 296#define tn_rdev tn_spec.tn_rdev 297#define tn_dir tn_spec.tn_dir 298#define tn_link tn_spec.tn_link 299#define tn_reg tn_spec.tn_reg 300#define tn_fifo tn_spec.tn_fifo 301 302#define TMPFS_NODE_LOCK(node) mtx_lock(&(node)->tn_interlock) 303#define TMPFS_NODE_UNLOCK(node) mtx_unlock(&(node)->tn_interlock) 304#define TMPFS_NODE_MTX(node) (&(node)->tn_interlock) 305#define TMPFS_NODE_ASSERT_LOCKED(node) mtx_assert(TMPFS_NODE_MTX(node), \ 306 MA_OWNED) 307 308#ifdef INVARIANTS 309#define TMPFS_ASSERT_LOCKED(node) do { \ 310 MPASS((node) != NULL); \ 311 MPASS((node)->tn_vnode != NULL); \ 312 ASSERT_VOP_LOCKED((node)->tn_vnode, "tmpfs assert"); \ 313 } while (0) 314#else 315#define TMPFS_ASSERT_LOCKED(node) (void)0 316#endif 317 318#define TMPFS_VNODE_ALLOCATING 1 319#define TMPFS_VNODE_WANT 2 320#define TMPFS_VNODE_DOOMED 4 321#define TMPFS_VNODE_WRECLAIM 8 322 323/* 324 * Internal representation of a tmpfs mount point. 325 */ 326struct tmpfs_mount { 327 /* 328 * Maximum number of memory pages available for use by the file 329 * system, set during mount time. This variable must never be 330 * used directly as it may be bigger than the current amount of 331 * free memory; in the extreme case, it will hold the ULONG_MAX 332 * value. 333 */ 334 u_long tm_pages_max; 335 336 /* Number of pages in use by the file system. */ 337 u_long tm_pages_used; 338 339 /* 340 * Pointer to the node representing the root directory of this 341 * file system. 342 */ 343 struct tmpfs_node * tm_root; 344 345 /* 346 * Maximum number of possible nodes for this file system; set 347 * during mount time. We need a hard limit on the maximum number 348 * of nodes to avoid allocating too much of them; their objects 349 * cannot be released until the file system is unmounted. 350 * Otherwise, we could easily run out of memory by creating lots 351 * of empty files and then simply removing them. 352 */ 353 ino_t tm_nodes_max; 354 355 /* unrhdr used to allocate inode numbers */ 356 struct unrhdr * tm_ino_unr; 357 358 /* Number of nodes currently that are in use. */ 359 ino_t tm_nodes_inuse; 360 361 /* maximum representable file size */ 362 u_int64_t tm_maxfilesize; 363 364 /* 365 * The used list contains all nodes that are currently used by 366 * the file system; i.e., they refer to existing files. 367 */ 368 struct tmpfs_node_list tm_nodes_used; 369 370 /* All node lock to protect the node list and tmp_pages_used. */ 371 struct mtx tm_allnode_lock; 372 373 /* Zones used to store file system meta data, per tmpfs mount. */ 374 uma_zone_t tm_dirent_pool; 375 uma_zone_t tm_node_pool; 376 377 /* Read-only status. */ 378 int tm_ronly; 379}; 380#define TMPFS_LOCK(tm) mtx_lock(&(tm)->tm_allnode_lock) 381#define TMPFS_UNLOCK(tm) mtx_unlock(&(tm)->tm_allnode_lock) 382#define TMPFS_MP_ASSERT_LOCKED(tm) mtx_assert(&(tm)->tm_allnode_lock, MA_OWNED) 383 384/* 385 * This structure maps a file identifier to a tmpfs node. Used by the 386 * NFS code. 387 */ 388struct tmpfs_fid { 389 uint16_t tf_len; 390 uint16_t tf_pad; 391 ino_t tf_id; 392 unsigned long tf_gen; 393}; 394 395struct tmpfs_dir_cursor { 396 struct tmpfs_dirent *tdc_current; 397 struct tmpfs_dirent *tdc_tree; 398}; 399 400#ifdef _KERNEL 401/* 402 * Prototypes for tmpfs_subr.c. 403 */ 404 405int tmpfs_alloc_node(struct mount *mp, struct tmpfs_mount *, enum vtype, 406 uid_t uid, gid_t gid, mode_t mode, struct tmpfs_node *, 407 char *, dev_t, struct tmpfs_node **); 408void tmpfs_free_node(struct tmpfs_mount *, struct tmpfs_node *); 409int tmpfs_alloc_dirent(struct tmpfs_mount *, struct tmpfs_node *, 410 const char *, u_int, struct tmpfs_dirent **); 411void tmpfs_free_dirent(struct tmpfs_mount *, struct tmpfs_dirent *); 412void tmpfs_dirent_init(struct tmpfs_dirent *, const char *, u_int); 413void tmpfs_destroy_vobject(struct vnode *vp, vm_object_t obj); 414int tmpfs_alloc_vp(struct mount *, struct tmpfs_node *, int, 415 struct vnode **); 416void tmpfs_free_vp(struct vnode *); 417int tmpfs_alloc_file(struct vnode *, struct vnode **, struct vattr *, 418 struct componentname *, char *); 419void tmpfs_check_mtime(struct vnode *); 420void tmpfs_dir_attach(struct vnode *, struct tmpfs_dirent *); 421void tmpfs_dir_detach(struct vnode *, struct tmpfs_dirent *); 422void tmpfs_dir_destroy(struct tmpfs_mount *, struct tmpfs_node *); 423struct tmpfs_dirent * tmpfs_dir_lookup(struct tmpfs_node *node, 424 struct tmpfs_node *f, 425 struct componentname *cnp); 426int tmpfs_dir_getdents(struct tmpfs_node *, struct uio *, int, 427 u_long *, int *); 428int tmpfs_dir_whiteout_add(struct vnode *, struct componentname *); 429void tmpfs_dir_whiteout_remove(struct vnode *, struct componentname *); 430int tmpfs_reg_resize(struct vnode *, off_t, boolean_t); 431int tmpfs_chflags(struct vnode *, u_long, struct ucred *, struct thread *); 432int tmpfs_chmod(struct vnode *, mode_t, struct ucred *, struct thread *); 433int tmpfs_chown(struct vnode *, uid_t, gid_t, struct ucred *, 434 struct thread *); 435int tmpfs_chsize(struct vnode *, u_quad_t, struct ucred *, struct thread *); 436int tmpfs_chtimes(struct vnode *, struct vattr *, struct ucred *cred, 437 struct thread *); 438void tmpfs_itimes(struct vnode *, const struct timespec *, 439 const struct timespec *); 440 441void tmpfs_set_status(struct tmpfs_node *node, int status); 442void tmpfs_update(struct vnode *); 443int tmpfs_truncate(struct vnode *, off_t); 444struct tmpfs_dirent *tmpfs_dir_first(struct tmpfs_node *dnode, 445 struct tmpfs_dir_cursor *dc); 446struct tmpfs_dirent *tmpfs_dir_next(struct tmpfs_node *dnode, 447 struct tmpfs_dir_cursor *dc); 448 449/* 450 * Convenience macros to simplify some logical expressions. 451 */ 452#define IMPLIES(a, b) (!(a) || (b)) 453#define IFF(a, b) (IMPLIES(a, b) && IMPLIES(b, a)) 454 455/* 456 * Checks that the directory entry pointed by 'de' matches the name 'name' 457 * with a length of 'len'. 458 */ 459#define TMPFS_DIRENT_MATCHES(de, name, len) \ 460 (de->td_namelen == len && \ 461 bcmp((de)->ud.td_name, (name), (de)->td_namelen) == 0) 462 463/* 464 * Ensures that the node pointed by 'node' is a directory and that its 465 * contents are consistent with respect to directories. 466 */ 467#define TMPFS_VALIDATE_DIR(node) do { \ 468 MPASS((node)->tn_type == VDIR); \ 469 MPASS((node)->tn_size % sizeof(struct tmpfs_dirent) == 0); \ 470} while (0) 471 472/* 473 * Amount of memory pages to reserve for the system (e.g., to not use by 474 * tmpfs). 475 */ 476#define TMPFS_PAGES_MINRESERVED (4 * 1024 * 1024 / PAGE_SIZE) 477 478size_t tmpfs_mem_avail(void); 479 480size_t tmpfs_pages_used(struct tmpfs_mount *tmp); 481 482#endif 483 484/* 485 * Macros/functions to convert from generic data structures to tmpfs 486 * specific ones. 487 */ 488 489static inline struct tmpfs_mount * 490VFS_TO_TMPFS(struct mount *mp) 491{ 492 struct tmpfs_mount *tmp; 493 494 MPASS(mp != NULL && mp->mnt_data != NULL); 495 tmp = (struct tmpfs_mount *)mp->mnt_data; 496 return (tmp); 497} 498 499static inline struct tmpfs_node * 500VP_TO_TMPFS_NODE(struct vnode *vp) 501{ 502 struct tmpfs_node *node; 503 504 MPASS(vp != NULL && vp->v_data != NULL); 505 node = (struct tmpfs_node *)vp->v_data; 506 return (node); 507} 508 509static inline struct tmpfs_node * 510VP_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