tmpfs.h revision 1.13 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