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: src/sys/fs/tmpfs/tmpfs.h,v 1.18 2009/10/11 07:03:56 delphij Exp $ 33 */ 34 35 #ifndef _VFS_TMPFS_TMPFS_H_ 36 #define _VFS_TMPFS_TMPFS_H_ 37 38 /* --------------------------------------------------------------------- 39 * KERNEL-SPECIFIC DEFINITIONS 40 * --------------------------------------------------------------------- */ 41 #include <sys/dirent.h> 42 #include <sys/mount.h> 43 #include <sys/tree.h> 44 #include <sys/vnode.h> 45 #include <sys/file.h> 46 #include <sys/lock.h> 47 #include <sys/lockf.h> 48 #include <sys/mutex.h> 49 #include <sys/objcache.h> 50 51 /* --------------------------------------------------------------------- */ 52 #include <sys/malloc.h> 53 #include <sys/systm.h> 54 #include <sys/vmmeter.h> 55 #include <vm/swap_pager.h> 56 57 MALLOC_DECLARE(M_TMPFSMNT); 58 59 /* --------------------------------------------------------------------- */ 60 61 /* 62 * Internal representation of a tmpfs directory entry. 63 */ 64 struct tmpfs_dirent { 65 RB_ENTRY(tmpfs_dirent) rb_node; 66 67 /* Length of the name stored in this directory entry. This avoids 68 * the need to recalculate it every time the name is used. */ 69 uint16_t td_namelen; 70 71 /* The name of the entry, allocated from a string pool. This 72 * string is not required to be zero-terminated; therefore, the 73 * td_namelen field must always be used when accessing its value. */ 74 char * td_name; 75 76 /* Pointer to the node this entry refers to. */ 77 struct tmpfs_node * td_node; 78 }; 79 80 struct tmpfs_dirtree; 81 RB_HEAD(tmpfs_dirtree, tmpfs_dirent); 82 RB_PROTOTYPE(tmpfs_dirtree, tmpfs_dirent, rb_node, 83 tmpfs_dirtree_compare); 84 85 86 /* A directory in tmpfs holds a set of directory entries, which in 87 * turn point to other files (which can be directories themselves). 88 * 89 * In tmpfs, this set is managed by a red-black tree, whose root is defined 90 * by the struct tmpfs_dirtree type. 91 * 92 * It is important 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 99 /* Each entry in a directory has a cookie that identifies it. Cookies 100 * supersede offsets within directories because, given how tmpfs stores 101 * directories in memory, there is no such thing as an offset. (Emulating 102 * a real offset could be very difficult.) 103 * 104 * The '.', '..' and the end of directory markers have fixed cookies which 105 * cannot collide with the cookies generated by other entries. The cookies 106 * for the other entries are generated based on the memory address on which 107 * stores their information is stored. 108 * 109 * Ideally, using the entry's memory pointer as the cookie would be enough 110 * to represent it and it wouldn't cause collisions in any system. 111 * Unfortunately, this results in "offsets" with very large values which 112 * later raise problems in the Linux compatibility layer (and maybe in other 113 * places) as described in PR kern/32034. Hence we need to workaround this 114 * with a rather ugly hack. 115 * 116 * Linux 32-bit binaries, unless built with _FILE_OFFSET_BITS=64, have off_t 117 * set to 'long', which is a 32-bit *signed* long integer. Regardless of 118 * the macro value, GLIBC (2.3 at least) always uses the getdents64 119 * system call (when calling readdir) which internally returns off64_t 120 * offsets. In order to make 32-bit binaries work, *GLIBC* converts the 121 * 64-bit values returned by the kernel to 32-bit ones and aborts with 122 * EOVERFLOW if the conversion results in values that won't fit in 32-bit 123 * integers (which it assumes is because the directory is extremely large). 124 * This wouldn't cause problems if we were dealing with unsigned integers, 125 * but as we have signed integers, this check fails due to sign expansion. 126 * 127 * For example, consider that the kernel returns the 0xc1234567 cookie to 128 * userspace in a off64_t integer. Later on, GLIBC casts this value to 129 * off_t (remember, signed) with code similar to: 130 * system call returns the offset in kernel_value; 131 * off_t casted_value = kernel_value; 132 * if (sizeof(off_t) != sizeof(off64_t) && 133 * kernel_value != casted_value) 134 * error! 135 * In this case, casted_value still has 0xc1234567, but when it is compared 136 * for equality against kernel_value, it is promoted to a 64-bit integer and 137 * becomes 0xffffffffc1234567, which is different than 0x00000000c1234567. 138 * Then, GLIBC assumes this is because the directory is very large. 139 * 140 * Given that all the above happens in user-space, we have no control over 141 * it; therefore we must workaround the issue here. We do this by 142 * truncating the pointer value to a 32-bit integer and hope that there 143 * won't be collisions. In fact, this will not cause any problems in 144 * 32-bit platforms but some might arise in 64-bit machines (I'm not sure 145 * if they can happen at all in practice). 146 * 147 * XXX A nicer solution shall be attempted. */ 148 #ifdef _KERNEL 149 #define TMPFS_DIRCOOKIE_DOT 0 150 #define TMPFS_DIRCOOKIE_DOTDOT 1 151 #define TMPFS_DIRCOOKIE_EOF 2 152 static __inline 153 off_t 154 tmpfs_dircookie(struct tmpfs_dirent *de) 155 { 156 off_t cookie; 157 158 cookie = ((off_t)(uintptr_t)de >> 1) & 0x7FFFFFFF; 159 KKASSERT(cookie != TMPFS_DIRCOOKIE_DOT); 160 KKASSERT(cookie != TMPFS_DIRCOOKIE_DOTDOT); 161 KKASSERT(cookie != TMPFS_DIRCOOKIE_EOF); 162 163 return cookie; 164 } 165 #endif 166 167 /* --------------------------------------------------------------------- */ 168 169 /* 170 * Internal representation of a tmpfs file system node. 171 * 172 * This structure is splitted in two parts: one holds attributes common 173 * to all file types and the other holds data that is only applicable to 174 * a particular type. The code must be careful to only access those 175 * attributes that are actually allowed by the node's type. 176 * 177 * 178 * Below is the key of locks used to protected the fields in the following 179 * structures. 180 * 181 */ 182 struct tmpfs_node { 183 /* Doubly-linked list entry which links all existing nodes for a 184 * single file system. This is provided to ease the removal of 185 * all nodes during the unmount operation. */ 186 LIST_ENTRY(tmpfs_node) tn_entries; 187 188 /* The node's type. Any of 'VBLK', 'VCHR', 'VDIR', 'VFIFO', 189 * 'VLNK', 'VREG' and 'VSOCK' is allowed. The usage of vnode 190 * types instead of a custom enumeration is to make things simpler 191 * and faster, as we do not need to convert between two types. */ 192 enum vtype tn_type; 193 194 /* Node identifier. */ 195 ino_t tn_id; 196 197 /* Node's internal status. This is used by several file system 198 * operations to do modifications to the node in a delayed 199 * fashion. */ 200 int tn_status; 201 #define TMPFS_NODE_ACCESSED (1 << 1) 202 #define TMPFS_NODE_MODIFIED (1 << 2) 203 #define TMPFS_NODE_CHANGED (1 << 3) 204 205 /* The node size. It does not necessarily match the real amount 206 * of memory consumed by it. */ 207 off_t tn_size; 208 209 /* Generic node attributes. */ 210 uid_t tn_uid; 211 gid_t tn_gid; 212 mode_t tn_mode; 213 int tn_flags; 214 nlink_t tn_links; 215 int32_t tn_atime; 216 int32_t tn_atimensec; 217 int32_t tn_mtime; 218 int32_t tn_mtimensec; 219 int32_t tn_ctime; 220 int32_t tn_ctimensec; 221 unsigned long tn_gen; 222 struct lockf tn_advlock; 223 224 /* As there is a single vnode for each active file within the 225 * system, care has to be taken to avoid allocating more than one 226 * vnode per file. In order to do this, a bidirectional association 227 * is kept between vnodes and nodes. 228 * 229 * Whenever a vnode is allocated, its v_data field is updated to 230 * point to the node it references. At the same time, the node's 231 * tn_vnode field is modified to point to the new vnode representing 232 * it. Further attempts to allocate a vnode for this same node will 233 * result in returning a new reference to the value stored in 234 * tn_vnode. 235 * 236 * May be NULL when the node is unused (that is, no vnode has been 237 * allocated for it or it has been reclaimed). */ 238 struct vnode * tn_vnode; 239 240 /* interlock to protect tn_vpstate */ 241 struct lock tn_interlock; 242 243 /* Identify if current node has vnode assiocate with 244 * or allocating vnode. 245 */ 246 int tn_vpstate; 247 248 /* misc data field for different tn_type node */ 249 union { 250 /* Valid when tn_type == VBLK || tn_type == VCHR. */ 251 dev_t tn_rdev; /*int32_t ?*/ 252 253 /* Valid when tn_type == VDIR. */ 254 struct tn_dir{ 255 /* Pointer to the parent directory. The root 256 * directory has a pointer to itself in this field; 257 * this property identifies the root node. */ 258 struct tmpfs_node * tn_parent; 259 260 /* Root of a red-black tree that links the contents of 261 * the directory together. See above for a 262 * description of its contents. */ 263 struct tmpfs_dirtree tn_dirtree; 264 265 /* Number and pointer of the first directory entry 266 * returned by the readdir operation if it were 267 * called again to continue reading data from the 268 * same directory as before. This is used to speed 269 * up reads of long directories, assuming that no 270 * more than one read is in progress at a given time. 271 * Otherwise, these values are discarded and a linear 272 * scan is performed from the beginning up to the 273 * point where readdir starts returning values. */ 274 off_t tn_readdir_lastn; 275 struct tmpfs_dirent * tn_readdir_lastp; 276 }tn_dir; 277 278 /* Valid when tn_type == VLNK. */ 279 /* The link's target, allocated from a string pool. */ 280 char * tn_link; 281 282 /* Valid when tn_type == VREG. */ 283 struct tn_reg { 284 /* The contents of regular files stored in a tmpfs 285 * file system are represented by a single anonymous 286 * memory object (aobj, for short). The aobj provides 287 * direct access to any position within the file, 288 * because its contents are always mapped in a 289 * contiguous region of virtual memory. It is a task 290 * of the memory management subsystem (see uvm(9)) to 291 * issue the required page ins or page outs whenever 292 * a position within the file is accessed. */ 293 vm_object_t tn_aobj; 294 size_t tn_aobj_pages; 295 296 }tn_reg; 297 298 /* Valid when tn_type = VFIFO */ 299 struct tn_fifo { 300 int (*tn_fo_read) (struct file *fp, struct uio *uio, 301 struct ucred *cred, int flags); 302 int (*tn_fo_write) (struct file *fp, struct uio *uio, 303 struct ucred *cred, int flags); 304 }tn_fifo; 305 }tn_spec; 306 }; 307 LIST_HEAD(tmpfs_node_list, tmpfs_node); 308 309 #define tn_rdev tn_spec.tn_rdev 310 #define tn_dir tn_spec.tn_dir 311 #define tn_link tn_spec.tn_link 312 #define tn_reg tn_spec.tn_reg 313 #define tn_fifo tn_spec.tn_fifo 314 315 #define TMPFS_NODE_LOCK(node) lockmgr(&(node)->tn_interlock, LK_EXCLUSIVE|LK_RETRY) 316 #define TMPFS_NODE_UNLOCK(node) lockmgr(&(node)->tn_interlock, LK_RELEASE) 317 #define TMPFS_NODE_MTX(node) (&(node)->tn_interlock) 318 319 #ifdef INVARIANTS 320 #define TMPFS_ASSERT_LOCKED(node) do { \ 321 KKASSERT(node != NULL); \ 322 KKASSERT(node->tn_vnode != NULL); \ 323 if (!vn_islocked(node->tn_vnode) && \ 324 (lockstatus(TMPFS_NODE_MTX(node), curthread) == LK_EXCLUSIVE )) \ 325 panic("tmpfs: node is not locked: %p", node); \ 326 } while (0) 327 #define TMPFS_ASSERT_ELOCKED(node) do { \ 328 KKASSERT((node) != NULL); \ 329 KKASSERT(lockstatus(TMPFS_NODE_MTX(node), curthread) == LK_EXCLUSIVE); \ 330 } while (0) 331 #else 332 #define TMPFS_ASSERT_LOCKED(node) (void)0 333 #define TMPFS_ASSERT_ELOCKED(node) (void)0 334 #endif 335 336 #define TMPFS_VNODE_ALLOCATING 1 337 #define TMPFS_VNODE_WANT 2 338 #define TMPFS_VNODE_DOOMED 4 339 /* --------------------------------------------------------------------- */ 340 341 /* 342 * Internal representation of a tmpfs mount point. 343 */ 344 struct tmpfs_mount { 345 /* Maximum number of memory pages available for use by the file 346 * system, set during mount time. This variable must never be 347 * used directly as it may be bigger than the current amount of 348 * free memory; in the extreme case, it will hold the SIZE_MAX 349 * value. Instead, use the TMPFS_PAGES_MAX macro. */ 350 vm_pindex_t tm_pages_max; 351 352 /* Number of pages in use by the file system. Cannot be bigger 353 * than the value returned by TMPFS_PAGES_MAX in any case. */ 354 vm_pindex_t tm_pages_used; 355 356 /* Pointer to the node representing the root directory of this 357 * file system. */ 358 struct tmpfs_node * tm_root; 359 360 /* Maximum number of possible nodes for this file system; set 361 * during mount time. We need a hard limit on the maximum number 362 * of nodes to avoid allocating too much of them; their objects 363 * cannot be released until the file system is unmounted. 364 * Otherwise, we could easily run out of memory by creating lots 365 * of empty files and then simply removing them. */ 366 ino_t tm_nodes_max; 367 368 /* Number of nodes currently that are in use. */ 369 ino_t tm_nodes_inuse; 370 371 /* maximum representable file size */ 372 u_int64_t tm_maxfilesize; 373 374 /* Nodes are organized in two different lists. The used list 375 * contains all nodes that are currently used by the file system; 376 * i.e., they refer to existing files. The available list contains 377 * all nodes that are currently available for use by new files. 378 * Nodes must be kept in this list (instead of deleting them) 379 * because we need to keep track of their generation number (tn_gen 380 * field). 381 * 382 * Note that nodes are lazily allocated: if the available list is 383 * empty and we have enough space to create more nodes, they will be 384 * created and inserted in the used list. Once these are released, 385 * they will go into the available list, remaining alive until the 386 * file system is unmounted. */ 387 struct tmpfs_node_list tm_nodes_used; 388 389 /* All node lock to protect the node list and tmp_pages_used */ 390 struct lock allnode_lock; 391 392 /* Per-mount malloc zones for tmpfs nodes, names, and dirents */ 393 struct malloc_type *tm_node_zone; 394 struct malloc_type *tm_dirent_zone; 395 struct malloc_type *tm_name_zone; 396 397 struct objcache_malloc_args tm_node_zone_malloc_args; 398 struct objcache_malloc_args tm_dirent_zone_malloc_args; 399 400 /* Pools used to store file system meta data. These are not shared 401 * across several instances of tmpfs for the reasons described in 402 * tmpfs_pool.c. */ 403 struct objcache *tm_dirent_pool; 404 struct objcache *tm_node_pool; 405 406 int tm_ino; 407 int tm_flags; 408 409 struct netexport tm_export; 410 }; 411 412 #define TMPFS_LOCK(tm) lockmgr(&(tm)->allnode_lock, LK_EXCLUSIVE|LK_RETRY) 413 #define TMPFS_UNLOCK(tm) lockmgr(&(tm)->allnode_lock, LK_RELEASE) 414 415 /* --------------------------------------------------------------------- */ 416 417 /* 418 * This structure maps a file identifier to a tmpfs node. Used by the 419 * NFS code. 420 */ 421 struct tmpfs_fid { 422 uint16_t tf_len; 423 uint16_t tf_pad; 424 ino_t tf_id; 425 unsigned long tf_gen; 426 }; 427 428 /* --------------------------------------------------------------------- */ 429 430 #ifdef _KERNEL 431 /* 432 * Prototypes for tmpfs_subr.c. 433 */ 434 435 int tmpfs_alloc_node(struct tmpfs_mount *, enum vtype, 436 uid_t uid, gid_t gid, mode_t mode, char *, int, int, 437 struct tmpfs_node **); 438 void tmpfs_free_node(struct tmpfs_mount *, struct tmpfs_node *); 439 int tmpfs_alloc_dirent(struct tmpfs_mount *, struct tmpfs_node *, 440 const char *, uint16_t, struct tmpfs_dirent **); 441 void tmpfs_free_dirent(struct tmpfs_mount *, struct tmpfs_dirent *); 442 int tmpfs_alloc_vp(struct mount *, struct tmpfs_node *, int, 443 struct vnode **); 444 void tmpfs_free_vp(struct vnode *); 445 int tmpfs_alloc_file(struct vnode *, struct vnode **, struct vattr *, 446 struct namecache *, struct ucred *, char *); 447 void tmpfs_dir_attach(struct tmpfs_node *, struct tmpfs_dirent *); 448 void tmpfs_dir_detach(struct tmpfs_node *, struct tmpfs_dirent *); 449 struct tmpfs_dirent * tmpfs_dir_lookup(struct tmpfs_node *node, 450 struct tmpfs_node *f, 451 struct namecache *ncp); 452 int tmpfs_dir_getdotdent(struct tmpfs_node *, struct uio *); 453 int tmpfs_dir_getdotdotdent(struct tmpfs_mount *, 454 struct tmpfs_node *, struct uio *); 455 struct tmpfs_dirent * tmpfs_dir_lookupbycookie(struct tmpfs_node *, off_t); 456 int tmpfs_dir_getdents(struct tmpfs_node *, struct uio *, off_t *); 457 int tmpfs_reg_resize(struct vnode *, off_t, int); 458 int tmpfs_chflags(struct vnode *, int, struct ucred *); 459 int tmpfs_chmod(struct vnode *, mode_t, struct ucred *); 460 int tmpfs_chown(struct vnode *, uid_t, gid_t, struct ucred *); 461 int tmpfs_chsize(struct vnode *, u_quad_t, struct ucred *); 462 int tmpfs_chtimes(struct vnode *, struct timespec *, struct timespec *, 463 int, struct ucred *); 464 void tmpfs_itimes(struct vnode *, const struct timespec *, 465 const struct timespec *); 466 467 void tmpfs_update(struct vnode *); 468 int tmpfs_truncate(struct vnode *, off_t); 469 int tmpfs_node_ctor(void *obj, void *privdata, int flags); 470 471 /* --------------------------------------------------------------------- */ 472 473 /* 474 * Convenience macros to simplify some logical expressions. 475 */ 476 #define IMPLIES(a, b) (!(a) || (b)) 477 #define IFF(a, b) (IMPLIES(a, b) && IMPLIES(b, a)) 478 479 /* --------------------------------------------------------------------- */ 480 481 /* 482 * Checks that the directory entry pointed by 'de' matches the name 'name' 483 * with a length of 'len'. 484 */ 485 #define TMPFS_DIRENT_MATCHES(de, name, len) \ 486 (de->td_namelen == (uint16_t)len && \ 487 bcmp((de)->td_name, (name), (de)->td_namelen) == 0) 488 489 /* --------------------------------------------------------------------- */ 490 491 /* 492 * Ensures that the node pointed by 'node' is a directory and that its 493 * contents are consistent with respect to directories. 494 */ 495 #define TMPFS_VALIDATE_DIR(node) \ 496 KKASSERT((node)->tn_type == VDIR); \ 497 KKASSERT((node)->tn_size % sizeof(struct tmpfs_dirent) == 0); \ 498 KKASSERT((node)->tn_dir.tn_readdir_lastp == NULL || \ 499 tmpfs_dircookie((node)->tn_dir.tn_readdir_lastp) == (node)->tn_dir.tn_readdir_lastn); 500 501 #endif 502 503 /* --------------------------------------------------------------------- */ 504 505 /* 506 * Macros/functions to convert from generic data structures to tmpfs 507 * specific ones. 508 */ 509 510 static inline 511 struct tmpfs_mount * 512 VFS_TO_TMPFS(struct mount *mp) 513 { 514 struct tmpfs_mount *tmp; 515 516 KKASSERT((mp) != NULL && (mp)->mnt_data != NULL); 517 tmp = (struct tmpfs_mount *)(mp)->mnt_data; 518 return tmp; 519 } 520 521 static inline 522 struct tmpfs_node * 523 VP_TO_TMPFS_NODE(struct vnode *vp) 524 { 525 struct tmpfs_node *node; 526 527 KKASSERT((vp) != NULL && (vp)->v_data != NULL); 528 node = (struct tmpfs_node *)vp->v_data; 529 return node; 530 } 531 532 static inline 533 struct tmpfs_node * 534 VP_TO_TMPFS_DIR(struct vnode *vp) 535 { 536 struct tmpfs_node *node; 537 538 node = VP_TO_TMPFS_NODE(vp); 539 TMPFS_VALIDATE_DIR(node); 540 return node; 541 } 542 543 /* --------------------------------------------------------------------- */ 544 /* 545 * buffer cache size 546 */ 547 #define BSIZE (off_t)16384 /* buffer cache size*/ 548 #define BMASK (off_t)(BSIZE - 1) 549 550 #endif /* _VFS_TMPFS_TMPFS_H_ */ 551