FreeBSD/Linux Kernel Cross Reference
sys/fs/tmpfs/tmpfs.h
1 /* $NetBSD: tmpfs.h,v 1.26 2007/02/22 06:37:00 thorpej Exp $ */
2
3 /*-
4 * SPDX-License-Identifier: BSD-2-Clause-NetBSD
5 *
6 * Copyright (c) 2005, 2006 The NetBSD Foundation, Inc.
7 * All rights reserved.
8 *
9 * This code is derived from software contributed to The NetBSD Foundation
10 * by Julio M. Merino Vidal, developed as part of Google's Summer of Code
11 * 2005 program.
12 *
13 * Redistribution and use in source and binary forms, with or without
14 * modification, are permitted provided that the following conditions
15 * are met:
16 * 1. Redistributions of source code must retain the above copyright
17 * notice, this list of conditions and the following disclaimer.
18 * 2. Redistributions in binary form must reproduce the above copyright
19 * notice, this list of conditions and the following disclaimer in the
20 * documentation and/or other materials provided with the distribution.
21 *
22 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
23 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
24 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
25 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
26 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
27 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
28 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
29 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
30 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
31 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
32 * POSSIBILITY OF SUCH DAMAGE.
33 *
34 * $FreeBSD$
35 */
36
37 #ifndef _FS_TMPFS_TMPFS_H_
38 #define _FS_TMPFS_TMPFS_H_
39
40 #include <sys/cdefs.h>
41 #include <sys/queue.h>
42 #include <sys/tree.h>
43
44 #ifdef _SYS_MALLOC_H_
45 MALLOC_DECLARE(M_TMPFSNAME);
46 #endif
47
48 /*
49 * Internal representation of a tmpfs directory entry.
50 */
51
52 LIST_HEAD(tmpfs_dir_duphead, tmpfs_dirent);
53
54 struct tmpfs_dirent {
55 /*
56 * Depending on td_cookie flag entry can be of 3 types:
57 * - regular -- no hash collisions, stored in RB-Tree
58 * - duphead -- synthetic linked list head for dup entries
59 * - dup -- stored in linked list instead of RB-Tree
60 */
61 union {
62 /* regular and duphead entry types */
63 RB_ENTRY(tmpfs_dirent) td_entries;
64
65 /* dup entry type */
66 struct {
67 LIST_ENTRY(tmpfs_dirent) entries;
68 LIST_ENTRY(tmpfs_dirent) index_entries;
69 } td_dup;
70 } uh;
71
72 uint32_t td_cookie;
73 uint32_t td_hash;
74 u_int td_namelen;
75
76 /*
77 * Pointer to the node this entry refers to. In case this field
78 * is NULL, the node is a whiteout.
79 */
80 struct tmpfs_node * td_node;
81
82 union {
83 /*
84 * The name of the entry, allocated from a string pool. This
85 * string is not required to be zero-terminated.
86 */
87 char * td_name; /* regular, dup */
88 struct tmpfs_dir_duphead td_duphead; /* duphead */
89 } ud;
90 };
91
92 /*
93 * A directory in tmpfs holds a collection of directory entries, which
94 * in turn point to other files (which can be directories themselves).
95 *
96 * In tmpfs, this collection is managed by a RB-Tree, whose head is
97 * defined by the struct tmpfs_dir type.
98 *
99 * It is important to notice that directories do not have entries for . and
100 * .. as other file systems do. These can be generated when requested
101 * based on information available by other means, such as the pointer to
102 * the node itself in the former case or the pointer to the parent directory
103 * in the latter case. This is done to simplify tmpfs's code and, more
104 * importantly, to remove redundancy.
105 */
106 RB_HEAD(tmpfs_dir, tmpfs_dirent);
107
108 /*
109 * Each entry in a directory has a cookie that identifies it. Cookies
110 * supersede offsets within directories because, given how tmpfs stores
111 * directories in memory, there is no such thing as an offset.
112 *
113 * The '.', '..' and the end of directory markers have fixed cookies which
114 * cannot collide with the cookies generated by other entries. The cookies
115 * for the other entries are generated based on the file name hash value or
116 * unique number in case of name hash collision.
117 *
118 * To preserve compatibility cookies are limited to 31 bits.
119 */
120
121 #define TMPFS_DIRCOOKIE_DOT 0
122 #define TMPFS_DIRCOOKIE_DOTDOT 1
123 #define TMPFS_DIRCOOKIE_EOF 2
124 #define TMPFS_DIRCOOKIE_MASK ((off_t)0x3fffffffU)
125 #define TMPFS_DIRCOOKIE_MIN ((off_t)0x00000004U)
126 #define TMPFS_DIRCOOKIE_DUP ((off_t)0x40000000U)
127 #define TMPFS_DIRCOOKIE_DUPHEAD ((off_t)0x80000000U)
128 #define TMPFS_DIRCOOKIE_DUP_MIN TMPFS_DIRCOOKIE_DUP
129 #define TMPFS_DIRCOOKIE_DUP_MAX \
130 (TMPFS_DIRCOOKIE_DUP | TMPFS_DIRCOOKIE_MASK)
131
132 /*
133 * Internal representation of a tmpfs file system node.
134 *
135 * This structure is splitted in two parts: one holds attributes common
136 * to all file types and the other holds data that is only applicable to
137 * a particular type. The code must be careful to only access those
138 * attributes that are actually allowed by the node's type.
139 *
140 * Below is the key of locks used to protected the fields in the following
141 * structures.
142 * (v) vnode lock in exclusive mode
143 * (vi) vnode lock in exclusive mode, or vnode lock in shared vnode and
144 * tn_interlock
145 * (i) tn_interlock
146 * (m) tmpfs_mount tm_allnode_lock
147 * (c) stable after creation
148 */
149 struct tmpfs_node {
150 /*
151 * Doubly-linked list entry which links all existing nodes for
152 * a single file system. This is provided to ease the removal
153 * of all nodes during the unmount operation, and to support
154 * the implementation of VOP_VNTOCNP(). tn_attached is false
155 * when the node is removed from list and unlocked.
156 */
157 LIST_ENTRY(tmpfs_node) tn_entries; /* (m) */
158 bool tn_attached; /* (m) */
159
160 /*
161 * The node's type. Any of 'VBLK', 'VCHR', 'VDIR', 'VFIFO',
162 * 'VLNK', 'VREG' and 'VSOCK' is allowed. The usage of vnode
163 * types instead of a custom enumeration is to make things simpler
164 * and faster, as we do not need to convert between two types.
165 */
166 enum vtype tn_type; /* (c) */
167
168 /* Node identifier. */
169 ino_t tn_id; /* (c) */
170
171 /*
172 * Node's internal status. This is used by several file system
173 * operations to do modifications to the node in a delayed
174 * fashion.
175 */
176 int tn_status; /* (vi) */
177 #define TMPFS_NODE_ACCESSED (1 << 1)
178 #define TMPFS_NODE_MODIFIED (1 << 2)
179 #define TMPFS_NODE_CHANGED (1 << 3)
180
181 /*
182 * The node size. It does not necessarily match the real amount
183 * of memory consumed by it.
184 */
185 off_t tn_size; /* (v) */
186
187 /* Generic node attributes. */
188 uid_t tn_uid; /* (v) */
189 gid_t tn_gid; /* (v) */
190 mode_t tn_mode; /* (v) */
191 int tn_links; /* (v) */
192 u_long tn_flags; /* (v) */
193 struct timespec tn_atime; /* (vi) */
194 struct timespec tn_mtime; /* (vi) */
195 struct timespec tn_ctime; /* (vi) */
196 struct timespec tn_birthtime; /* (v) */
197 unsigned long tn_gen; /* (c) */
198
199 /*
200 * As there is a single vnode for each active file within the
201 * system, care has to be taken to avoid allocating more than one
202 * vnode per file. In order to do this, a bidirectional association
203 * is kept between vnodes and nodes.
204 *
205 * Whenever a vnode is allocated, its v_data field is updated to
206 * point to the node it references. At the same time, the node's
207 * tn_vnode field is modified to point to the new vnode representing
208 * it. Further attempts to allocate a vnode for this same node will
209 * result in returning a new reference to the value stored in
210 * tn_vnode.
211 *
212 * May be NULL when the node is unused (that is, no vnode has been
213 * allocated for it or it has been reclaimed).
214 */
215 struct vnode * tn_vnode; /* (i) */
216
217 /*
218 * Interlock to protect tn_vpstate, and tn_status under shared
219 * vnode lock.
220 */
221 struct mtx tn_interlock;
222
223 /*
224 * Identify if current node has vnode assiocate with
225 * or allocating vnode.
226 */
227 int tn_vpstate; /* (i) */
228
229 /* Transient refcounter on this node. */
230 u_int tn_refcount; /* (m) + (i) */
231
232 /* misc data field for different tn_type node */
233 union {
234 /* Valid when tn_type == VBLK || tn_type == VCHR. */
235 dev_t tn_rdev; /* (c) */
236
237 /* Valid when tn_type == VDIR. */
238 struct tn_dir {
239 /*
240 * Pointer to the parent directory. The root
241 * directory has a pointer to itself in this field;
242 * this property identifies the root node.
243 */
244 struct tmpfs_node * tn_parent;
245
246 /*
247 * Head of a tree that links the contents of
248 * the directory together.
249 */
250 struct tmpfs_dir tn_dirhead;
251
252 /*
253 * Head of a list the contains fake directory entries
254 * heads, i.e. entries with TMPFS_DIRCOOKIE_DUPHEAD
255 * flag.
256 */
257 struct tmpfs_dir_duphead tn_dupindex;
258
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.
267 */
268 off_t tn_readdir_lastn;
269 struct tmpfs_dirent * tn_readdir_lastp;
270 } tn_dir;
271
272 /* Valid when tn_type == VLNK. */
273 /* The link's target, allocated from a string pool. */
274 char * tn_link; /* (c) */
275
276 /* Valid when tn_type == VREG. */
277 struct tn_reg {
278 /*
279 * The contents of regular files stored in a
280 * tmpfs file system are represented by a
281 * single anonymous memory object (aobj, for
282 * short). The aobj provides direct access to
283 * any position within the file. It is a task
284 * of the memory management subsystem to issue
285 * the required page ins or page outs whenever
286 * a position within the file is accessed.
287 */
288 vm_object_t tn_aobj; /* (c) */
289 } tn_reg;
290 } tn_spec; /* (v) */
291 };
292 LIST_HEAD(tmpfs_node_list, tmpfs_node);
293
294 #define tn_rdev tn_spec.tn_rdev
295 #define tn_dir tn_spec.tn_dir
296 #define tn_link tn_spec.tn_link
297 #define tn_reg tn_spec.tn_reg
298 #define tn_fifo tn_spec.tn_fifo
299
300 #define TMPFS_LINK_MAX INT_MAX
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 */
326 struct tmpfs_mount {
327 /*
328 * Original value of the "size" parameter, for reference purposes,
329 * mostly.
330 */
331 off_t tm_size_max;
332 /*
333 * Maximum number of memory pages available for use by the file
334 * system, set during mount time. This variable must never be
335 * used directly as it may be bigger than the current amount of
336 * free memory; in the extreme case, it will hold the ULONG_MAX
337 * value.
338 */
339 u_long tm_pages_max;
340
341 /* Number of pages in use by the file system. */
342 u_long tm_pages_used;
343
344 /*
345 * Pointer to the node representing the root directory of this
346 * file system.
347 */
348 struct tmpfs_node * tm_root;
349
350 /*
351 * Maximum number of possible nodes for this file system; set
352 * during mount time. We need a hard limit on the maximum number
353 * of nodes to avoid allocating too much of them; their objects
354 * cannot be released until the file system is unmounted.
355 * Otherwise, we could easily run out of memory by creating lots
356 * of empty files and then simply removing them.
357 */
358 ino_t tm_nodes_max;
359
360 /* unrhdr used to allocate inode numbers */
361 struct unrhdr64 tm_ino_unr;
362
363 /* Number of nodes currently that are in use. */
364 ino_t tm_nodes_inuse;
365
366 /* Refcounter on this struct tmpfs_mount. */
367 uint64_t tm_refcount;
368
369 /* maximum representable file size */
370 u_int64_t tm_maxfilesize;
371
372 /*
373 * The used list contains all nodes that are currently used by
374 * the file system; i.e., they refer to existing files.
375 */
376 struct tmpfs_node_list tm_nodes_used;
377
378 /* All node lock to protect the node list and tmp_pages_used. */
379 struct mtx tm_allnode_lock;
380
381 /* Read-only status. */
382 bool tm_ronly;
383 /* Do not use namecache. */
384 bool tm_nonc;
385 };
386 #define TMPFS_LOCK(tm) mtx_lock(&(tm)->tm_allnode_lock)
387 #define TMPFS_UNLOCK(tm) mtx_unlock(&(tm)->tm_allnode_lock)
388 #define TMPFS_MP_ASSERT_LOCKED(tm) mtx_assert(&(tm)->tm_allnode_lock, MA_OWNED)
389
390 /*
391 * This structure maps a file identifier to a tmpfs node. Used by the
392 * NFS code.
393 */
394 struct tmpfs_fid_data {
395 ino_t tfd_id;
396 unsigned long tfd_gen;
397 };
398 _Static_assert(sizeof(struct tmpfs_fid_data) <= MAXFIDSZ,
399 "(struct tmpfs_fid_data) is larger than (struct fid).fid_data");
400
401 struct tmpfs_dir_cursor {
402 struct tmpfs_dirent *tdc_current;
403 struct tmpfs_dirent *tdc_tree;
404 };
405
406 #ifdef _KERNEL
407 /*
408 * Prototypes for tmpfs_subr.c.
409 */
410
411 void tmpfs_ref_node(struct tmpfs_node *node);
412 void tmpfs_ref_node_locked(struct tmpfs_node *node);
413 int tmpfs_alloc_node(struct mount *mp, struct tmpfs_mount *, enum vtype,
414 uid_t uid, gid_t gid, mode_t mode, struct tmpfs_node *,
415 char *, dev_t, struct tmpfs_node **);
416 void tmpfs_free_node(struct tmpfs_mount *, struct tmpfs_node *);
417 bool tmpfs_free_node_locked(struct tmpfs_mount *, struct tmpfs_node *, bool);
418 void tmpfs_free_tmp(struct tmpfs_mount *);
419 int tmpfs_alloc_dirent(struct tmpfs_mount *, struct tmpfs_node *,
420 const char *, u_int, struct tmpfs_dirent **);
421 void tmpfs_free_dirent(struct tmpfs_mount *, struct tmpfs_dirent *);
422 void tmpfs_dirent_init(struct tmpfs_dirent *, const char *, u_int);
423 void tmpfs_destroy_vobject(struct vnode *vp, vm_object_t obj);
424 int tmpfs_alloc_vp(struct mount *, struct tmpfs_node *, int,
425 struct vnode **);
426 void tmpfs_free_vp(struct vnode *);
427 int tmpfs_alloc_file(struct vnode *, struct vnode **, struct vattr *,
428 struct componentname *, char *);
429 void tmpfs_check_mtime(struct vnode *);
430 void tmpfs_dir_attach(struct vnode *, struct tmpfs_dirent *);
431 void tmpfs_dir_detach(struct vnode *, struct tmpfs_dirent *);
432 void tmpfs_dir_destroy(struct tmpfs_mount *, struct tmpfs_node *);
433 struct tmpfs_dirent * tmpfs_dir_lookup(struct tmpfs_node *node,
434 struct tmpfs_node *f,
435 struct componentname *cnp);
436 int tmpfs_dir_getdents(struct tmpfs_mount *, struct tmpfs_node *,
437 struct uio *, int, u_long *, int *);
438 int tmpfs_dir_whiteout_add(struct vnode *, struct componentname *);
439 void tmpfs_dir_whiteout_remove(struct vnode *, struct componentname *);
440 int tmpfs_reg_resize(struct vnode *, off_t, boolean_t);
441 int tmpfs_chflags(struct vnode *, u_long, struct ucred *, struct thread *);
442 int tmpfs_chmod(struct vnode *, mode_t, struct ucred *, struct thread *);
443 int tmpfs_chown(struct vnode *, uid_t, gid_t, struct ucred *,
444 struct thread *);
445 int tmpfs_chsize(struct vnode *, u_quad_t, struct ucred *, struct thread *);
446 int tmpfs_chtimes(struct vnode *, struct vattr *, struct ucred *cred,
447 struct thread *);
448 void tmpfs_itimes(struct vnode *, const struct timespec *,
449 const struct timespec *);
450
451 void tmpfs_set_status(struct tmpfs_mount *tm, struct tmpfs_node *node,
452 int status);
453 void tmpfs_update(struct vnode *);
454 int tmpfs_truncate(struct vnode *, off_t);
455 struct tmpfs_dirent *tmpfs_dir_first(struct tmpfs_node *dnode,
456 struct tmpfs_dir_cursor *dc);
457 struct tmpfs_dirent *tmpfs_dir_next(struct tmpfs_node *dnode,
458 struct tmpfs_dir_cursor *dc);
459
460 /*
461 * Convenience macros to simplify some logical expressions.
462 */
463 #define IMPLIES(a, b) (!(a) || (b))
464 #define IFF(a, b) (IMPLIES(a, b) && IMPLIES(b, a))
465
466 /*
467 * Checks that the directory entry pointed by 'de' matches the name 'name'
468 * with a length of 'len'.
469 */
470 #define TMPFS_DIRENT_MATCHES(de, name, len) \
471 (de->td_namelen == len && \
472 bcmp((de)->ud.td_name, (name), (de)->td_namelen) == 0)
473
474 /*
475 * Ensures that the node pointed by 'node' is a directory and that its
476 * contents are consistent with respect to directories.
477 */
478 #define TMPFS_VALIDATE_DIR(node) do { \
479 MPASS((node)->tn_type == VDIR); \
480 MPASS((node)->tn_size % sizeof(struct tmpfs_dirent) == 0); \
481 } while (0)
482
483 /*
484 * Amount of memory pages to reserve for the system (e.g., to not use by
485 * tmpfs).
486 */
487 #define TMPFS_PAGES_MINRESERVED (4 * 1024 * 1024 / PAGE_SIZE)
488
489 size_t tmpfs_mem_avail(void);
490 size_t tmpfs_pages_used(struct tmpfs_mount *tmp);
491 void tmpfs_subr_init(void);
492 void tmpfs_subr_uninit(void);
493
494 /*
495 * Macros/functions to convert from generic data structures to tmpfs
496 * specific ones.
497 */
498
499 static inline struct tmpfs_mount *
500 VFS_TO_TMPFS(struct mount *mp)
501 {
502 struct tmpfs_mount *tmp;
503
504 MPASS(mp != NULL && mp->mnt_data != NULL);
505 tmp = (struct tmpfs_mount *)mp->mnt_data;
506 return (tmp);
507 }
508
509 static inline struct tmpfs_node *
510 VP_TO_TMPFS_NODE(struct vnode *vp)
511 {
512 struct tmpfs_node *node;
513
514 MPASS(vp != NULL && vp->v_data != NULL);
515 node = (struct tmpfs_node *)vp->v_data;
516 return (node);
517 }
518
519 static inline struct tmpfs_node *
520 VP_TO_TMPFS_DIR(struct vnode *vp)
521 {
522 struct tmpfs_node *node;
523
524 node = VP_TO_TMPFS_NODE(vp);
525 TMPFS_VALIDATE_DIR(node);
526 return (node);
527 }
528
529 static inline bool
530 tmpfs_use_nc(struct vnode *vp)
531 {
532
533 return (!(VFS_TO_TMPFS(vp->v_mount)->tm_nonc));
534 }
535 #endif /* _KERNEL */
536
537 #endif /* _FS_TMPFS_TMPFS_H_ */
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