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 struct tmpfs_node { 178 /* Doubly-linked list entry which links all existing nodes for a 179 * single file system. This is provided to ease the removal of 180 * all nodes during the unmount operation. */ 181 LIST_ENTRY(tmpfs_node) tn_entries; 182 183 /* The node's type. Any of 'VBLK', 'VCHR', 'VDIR', 'VFIFO', 184 * 'VLNK', 'VREG' and 'VSOCK' is allowed. The usage of vnode 185 * types instead of a custom enumeration is to make things simpler 186 * and faster, as we do not need to convert between two types. */ 187 enum vtype tn_type; 188 189 /* Node identifier. */ 190 ino_t tn_id; 191 192 /* Node's internal status. This is used by several file system 193 * operations to do modifications to the node in a delayed 194 * fashion. */ 195 int tn_status; 196 #define TMPFS_NODE_ACCESSED (1 << 1) 197 #define TMPFS_NODE_MODIFIED (1 << 2) 198 #define TMPFS_NODE_CHANGED (1 << 3) 199 200 /* The node size. It does not necessarily match the real amount 201 * of memory consumed by it. */ 202 off_t tn_size; 203 204 /* Generic node attributes. */ 205 uid_t tn_uid; 206 gid_t tn_gid; 207 mode_t tn_mode; 208 int tn_flags; 209 nlink_t tn_links; /* requires mnt_token protection */ 210 int32_t tn_atime; 211 int32_t tn_atimensec; 212 int32_t tn_mtime; 213 int32_t tn_mtimensec; 214 int32_t tn_ctime; 215 int32_t tn_ctimensec; 216 unsigned long tn_gen; 217 struct lockf tn_advlock; 218 219 /* As there is a single vnode for each active file within the 220 * system, care has to be taken to avoid allocating more than one 221 * vnode per file. In order to do this, a bidirectional association 222 * is kept between vnodes and nodes. 223 * 224 * Whenever a vnode is allocated, its v_data field is updated to 225 * point to the node it references. At the same time, the node's 226 * tn_vnode field is modified to point to the new vnode representing 227 * it. Further attempts to allocate a vnode for this same node will 228 * result in returning a new reference to the value stored in 229 * tn_vnode. 230 * 231 * May be NULL when the node is unused (that is, no vnode has been 232 * allocated for it or it has been reclaimed). */ 233 struct vnode * tn_vnode; 234 235 /* interlock to protect tn_vpstate */ 236 struct lock tn_interlock; 237 238 /* Identify if current node has vnode assiocate with 239 * or allocating vnode. 240 */ 241 int tn_vpstate; 242 243 /* misc data field for different tn_type node */ 244 union { 245 /* Valid when tn_type == VBLK || tn_type == VCHR. */ 246 dev_t tn_rdev; /*int32_t ?*/ 247 248 /* Valid when tn_type == VDIR. */ 249 struct tn_dir { 250 /* Pointer to the parent directory. The root 251 * directory has a pointer to itself in this field; 252 * this property identifies the root node. */ 253 struct tmpfs_node * tn_parent; 254 255 /* Root of a red-black tree that links the contents of 256 * the directory together. See above for a 257 * description of its contents. */ 258 struct tmpfs_dirtree tn_dirtree; 259 260 /* Number and pointer of the first directory entry 261 * returned by the readdir operation if it were 262 * called again to continue reading data from the 263 * same directory as before. This is used to speed 264 * up reads of long directories, assuming that no 265 * more than one read is in progress at a given time. 266 * Otherwise, these values are discarded and a linear 267 * scan is performed from the beginning up to the 268 * point where readdir starts returning values. */ 269 off_t tn_readdir_lastn; 270 struct tmpfs_dirent * tn_readdir_lastp; 271 } tn_dir; 272 273 /* Valid when tn_type == VLNK. */ 274 /* The link's target, allocated from a string pool. */ 275 char * tn_link; 276 277 /* Valid when tn_type == VREG. */ 278 struct tn_reg { 279 /* The contents of regular files stored in a tmpfs 280 * file system are represented by a single anonymous 281 * memory object (aobj, for short). The aobj provides 282 * direct access to any position within the file, 283 * because its contents are always mapped in a 284 * contiguous region of virtual memory. It is a task 285 * of the memory management subsystem (see uvm(9)) to 286 * issue the required page ins or page outs whenever 287 * a position within the file is accessed. */ 288 vm_object_t tn_aobj; 289 size_t tn_aobj_pages; 290 291 } tn_reg; 292 293 /* Valid when tn_type = VFIFO */ 294 struct tn_fifo { 295 int (*tn_fo_read) (struct file *fp, struct uio *uio, 296 struct ucred *cred, int flags); 297 int (*tn_fo_write) (struct file *fp, struct uio *uio, 298 struct ucred *cred, int flags); 299 } tn_fifo; 300 } tn_spec; 301 }; 302 LIST_HEAD(tmpfs_node_list, tmpfs_node); 303 304 #define tn_rdev tn_spec.tn_rdev 305 #define tn_dir tn_spec.tn_dir 306 #define tn_link tn_spec.tn_link 307 #define tn_reg tn_spec.tn_reg 308 #define tn_fifo tn_spec.tn_fifo 309 310 #define TMPFS_NODE_LOCK(node) lockmgr(&(node)->tn_interlock, LK_EXCLUSIVE|LK_RETRY) 311 #define TMPFS_NODE_UNLOCK(node) lockmgr(&(node)->tn_interlock, LK_RELEASE) 312 #define TMPFS_NODE_MTX(node) (&(node)->tn_interlock) 313 314 #ifdef INVARIANTS 315 #define TMPFS_ASSERT_LOCKED(node) do { \ 316 KKASSERT(node != NULL); \ 317 KKASSERT(node->tn_vnode != NULL); \ 318 if (!vn_islocked(node->tn_vnode) && \ 319 (lockstatus(TMPFS_NODE_MTX(node), curthread) == LK_EXCLUSIVE )) \ 320 panic("tmpfs: node is not locked: %p", node); \ 321 } while (0) 322 #define TMPFS_ASSERT_ELOCKED(node) do { \ 323 KKASSERT((node) != NULL); \ 324 KKASSERT(lockstatus(TMPFS_NODE_MTX(node), curthread) == LK_EXCLUSIVE); \ 325 } while (0) 326 #else 327 #define TMPFS_ASSERT_LOCKED(node) (void)0 328 #define TMPFS_ASSERT_ELOCKED(node) (void)0 329 #endif 330 331 #define TMPFS_VNODE_ALLOCATING 1 332 #define TMPFS_VNODE_WANT 2 333 #define TMPFS_VNODE_DOOMED 4 334 /* --------------------------------------------------------------------- */ 335 336 /* 337 * Internal representation of a tmpfs mount point. 338 */ 339 struct tmpfs_mount { 340 struct mount *tm_mount; 341 342 /* Maximum number of memory pages available for use by the file 343 * system, set during mount time. This variable must never be 344 * used directly as it may be bigger than the current amount of 345 * free memory; in the extreme case, it will hold the SIZE_MAX 346 * value. Instead, use the TMPFS_PAGES_MAX macro. */ 347 vm_pindex_t tm_pages_max; 348 349 /* Number of pages in use by the file system. Cannot be bigger 350 * than the value returned by TMPFS_PAGES_MAX in any case. */ 351 vm_pindex_t tm_pages_used; 352 353 /* Pointer to the node representing the root directory of this 354 * file system. */ 355 struct tmpfs_node * tm_root; 356 357 /* Maximum number of possible nodes for this file system; set 358 * during mount time. We need a hard limit on the maximum number 359 * of nodes to avoid allocating too much of them; their objects 360 * cannot be released until the file system is unmounted. 361 * Otherwise, we could easily run out of memory by creating lots 362 * of empty files and then simply removing them. */ 363 ino_t tm_nodes_max; 364 365 /* Number of nodes currently that are in use. */ 366 ino_t tm_nodes_inuse; 367 368 /* maximum representable file size */ 369 u_int64_t tm_maxfilesize; 370 371 /* Nodes are organized in two different lists. The used list 372 * contains all nodes that are currently used by the file system; 373 * i.e., they refer to existing files. The available list contains 374 * all nodes that are currently available for use by new files. 375 * Nodes must be kept in this list (instead of deleting them) 376 * because we need to keep track of their generation number (tn_gen 377 * field). 378 * 379 * Note that nodes are lazily allocated: if the available list is 380 * empty and we have enough space to create more nodes, they will be 381 * created and inserted in the used list. Once these are released, 382 * they will go into the available list, remaining alive until the 383 * file system is unmounted. */ 384 struct tmpfs_node_list tm_nodes_used; 385 386 /* Per-mount malloc zones for tmpfs nodes, names, and dirents */ 387 struct malloc_type *tm_node_zone; 388 struct malloc_type *tm_dirent_zone; 389 struct malloc_type *tm_name_zone; 390 391 struct objcache_malloc_args tm_node_zone_malloc_args; 392 struct objcache_malloc_args tm_dirent_zone_malloc_args; 393 394 /* Pools used to store file system meta data. */ 395 struct objcache *tm_dirent_pool; 396 struct objcache *tm_node_pool; 397 398 int tm_ino; 399 int tm_flags; 400 401 struct netexport tm_export; 402 403 struct mount *tm_mnt; 404 }; 405 406 #define TMPFS_LOCK(tm) lwkt_gettoken(&(tm)->tm_mount->mnt_token) 407 #define TMPFS_UNLOCK(tm) lwkt_reltoken(&(tm)->tm_mount->mnt_token) 408 409 /* --------------------------------------------------------------------- */ 410 411 /* 412 * This structure maps a file identifier to a tmpfs node. Used by the 413 * NFS code. 414 */ 415 struct tmpfs_fid { 416 uint16_t tf_len; 417 uint16_t tf_pad; 418 ino_t tf_id; 419 unsigned long tf_gen; 420 }; 421 422 /* --------------------------------------------------------------------- */ 423 424 #ifdef _KERNEL 425 /* 426 * Prototypes for tmpfs_subr.c. 427 */ 428 429 int tmpfs_alloc_node(struct tmpfs_mount *, enum vtype, 430 uid_t uid, gid_t gid, mode_t mode, char *, int, int, 431 struct tmpfs_node **); 432 void tmpfs_free_node(struct tmpfs_mount *, struct tmpfs_node *); 433 int tmpfs_alloc_dirent(struct tmpfs_mount *, struct tmpfs_node *, 434 const char *, uint16_t, struct tmpfs_dirent **); 435 void tmpfs_free_dirent(struct tmpfs_mount *, struct tmpfs_dirent *); 436 int tmpfs_alloc_vp(struct mount *, struct tmpfs_node *, int, 437 struct vnode **); 438 void tmpfs_free_vp(struct vnode *); 439 int tmpfs_alloc_file(struct vnode *, struct vnode **, struct vattr *, 440 struct namecache *, struct ucred *, char *); 441 void tmpfs_dir_attach(struct tmpfs_node *, struct tmpfs_dirent *); 442 void tmpfs_dir_detach(struct tmpfs_node *, struct tmpfs_dirent *); 443 struct tmpfs_dirent * tmpfs_dir_lookup(struct tmpfs_node *node, 444 struct tmpfs_node *f, 445 struct namecache *ncp); 446 int tmpfs_dir_getdotdent(struct tmpfs_node *, struct uio *); 447 int tmpfs_dir_getdotdotdent(struct tmpfs_mount *, 448 struct tmpfs_node *, struct uio *); 449 struct tmpfs_dirent * tmpfs_dir_lookupbycookie(struct tmpfs_node *, off_t); 450 int tmpfs_dir_getdents(struct tmpfs_node *, struct uio *, off_t *); 451 int tmpfs_reg_resize(struct vnode *, off_t, int); 452 int tmpfs_chflags(struct vnode *, int, struct ucred *); 453 int tmpfs_chmod(struct vnode *, mode_t, struct ucred *); 454 int tmpfs_chown(struct vnode *, uid_t, gid_t, struct ucred *); 455 int tmpfs_chsize(struct vnode *, u_quad_t, struct ucred *); 456 int tmpfs_chtimes(struct vnode *, struct timespec *, struct timespec *, 457 int, struct ucred *); 458 void tmpfs_itimes(struct vnode *, const struct timespec *, 459 const struct timespec *); 460 461 void tmpfs_update(struct vnode *); 462 int tmpfs_truncate(struct vnode *, off_t); 463 int tmpfs_node_ctor(void *obj, void *privdata, int flags); 464 465 /* --------------------------------------------------------------------- */ 466 467 /* 468 * Convenience macros to simplify some logical expressions. 469 */ 470 #define IMPLIES(a, b) (!(a) || (b)) 471 #define IFF(a, b) (IMPLIES(a, b) && IMPLIES(b, a)) 472 473 /* --------------------------------------------------------------------- */ 474 475 /* 476 * Checks that the directory entry pointed by 'de' matches the name 'name' 477 * with a length of 'len'. 478 */ 479 #define TMPFS_DIRENT_MATCHES(de, name, len) \ 480 (de->td_namelen == (uint16_t)len && \ 481 bcmp((de)->td_name, (name), (de)->td_namelen) == 0) 482 483 /* --------------------------------------------------------------------- */ 484 485 /* 486 * Ensures that the node pointed by 'node' is a directory and that its 487 * contents are consistent with respect to directories. 488 */ 489 #define TMPFS_VALIDATE_DIR(node) \ 490 KKASSERT((node)->tn_type == VDIR); \ 491 KKASSERT((node)->tn_size % sizeof(struct tmpfs_dirent) == 0); \ 492 KKASSERT((node)->tn_dir.tn_readdir_lastp == NULL || \ 493 tmpfs_dircookie((node)->tn_dir.tn_readdir_lastp) == (node)->tn_dir.tn_readdir_lastn); 494 495 #endif 496 497 /* --------------------------------------------------------------------- */ 498 499 /* 500 * Macros/functions to convert from generic data structures to tmpfs 501 * specific ones. 502 */ 503 504 static inline 505 struct tmpfs_mount * 506 VFS_TO_TMPFS(struct mount *mp) 507 { 508 struct tmpfs_mount *tmp; 509 510 KKASSERT((mp) != NULL && (mp)->mnt_data != NULL); 511 tmp = (struct tmpfs_mount *)(mp)->mnt_data; 512 return tmp; 513 } 514 515 static inline 516 struct tmpfs_node * 517 VP_TO_TMPFS_NODE(struct vnode *vp) 518 { 519 struct tmpfs_node *node; 520 521 KKASSERT((vp) != NULL && (vp)->v_data != NULL); 522 node = (struct tmpfs_node *)vp->v_data; 523 return node; 524 } 525 526 static inline 527 struct tmpfs_node * 528 VP_TO_TMPFS_DIR(struct vnode *vp) 529 { 530 struct tmpfs_node *node; 531 532 node = VP_TO_TMPFS_NODE(vp); 533 TMPFS_VALIDATE_DIR(node); 534 return node; 535 } 536 537 /* --------------------------------------------------------------------- */ 538 /* 539 * buffer cache size 540 */ 541 #define BSIZE (off_t)16384 /* buffer cache size*/ 542 #define BMASK (off_t)(BSIZE - 1) 543 544 #endif /* _VFS_TMPFS_TMPFS_H_ */ 545