tmpfs.h revision 1.13.4.1 1 /* $NetBSD: tmpfs.h,v 1.13.4.1 2006/09/09 02:57:06 rpaulo 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 * 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 #include <sys/dirent.h>
47 #include <sys/mount.h>
48 #include <sys/queue.h>
49 #include <sys/vnode.h>
50
51 #if defined(_KERNEL)
52 #include <fs/tmpfs/tmpfs_pool.h>
53 #endif /* defined(_KERNEL) */
54
55 /* --------------------------------------------------------------------- */
56
57 /*
58 * Internal representation of a tmpfs directory entry.
59 */
60 struct tmpfs_dirent {
61 TAILQ_ENTRY(tmpfs_dirent) td_entries;
62
63 /* Length of the name stored in this directory entry. This avoids
64 * the need to recalculate it every time the name is used. */
65 uint16_t td_namelen;
66
67 /* The name of the entry, allocated from a string pool. This
68 * string is not required to be zero-terminated; therefore, the
69 * td_namelen field must always be used when accessing its value. */
70 char * td_name;
71
72 /* Pointer to the node this entry refers to. */
73 struct tmpfs_node * td_node;
74 };
75
76 /* A directory in tmpfs holds a sorted list of directory entries, which in
77 * turn point to other files (which can be directories themselves).
78 *
79 * In tmpfs, this list is managed by a tail queue, whose head is defined by
80 * the struct tmpfs_dir type.
81 *
82 * It is imporant to notice that directories do not have entries for . and
83 * .. as other file systems do. These can be generated when requested
84 * based on information available by other means, such as the pointer to
85 * the node itself in the former case or the pointer to the parent directory
86 * in the latter case. This is done to simplify tmpfs's code and, more
87 * importantly, to remove redundancy. */
88 TAILQ_HEAD(tmpfs_dir, tmpfs_dirent);
89
90 #define TMPFS_DIRCOOKIE(dirent) ((off_t)(uintptr_t)(dirent))
91 #define TMPFS_DIRCOOKIE_DOT 0
92 #define TMPFS_DIRCOOKIE_DOTDOT 1
93 #define TMPFS_DIRCOOKIE_EOF 2
94
95 /* --------------------------------------------------------------------- */
96
97 /*
98 * Internal representation of a tmpfs file system node.
99 *
100 * This structure is splitted in two parts: one holds attributes common
101 * to all file types and the other holds data that is only applicable to
102 * a particular type. The code must be careful to only access those
103 * attributes that are actually allowed by the node's type.
104 */
105 struct tmpfs_node {
106 /* Doubly-linked list entry which links all existing nodes for a
107 * single file system. This is provided to ease the removal of
108 * all nodes during the unmount operation. */
109 LIST_ENTRY(tmpfs_node) tn_entries;
110
111 /* The node's type. Any of 'VBLK', 'VCHR', 'VDIR', 'VFIFO',
112 * 'VLNK', 'VREG' and 'VSOCK' is allowed. The usage of vnode
113 * types instead of a custom enumeration is to make things simpler
114 * and faster, as we do not need to convert between two types. */
115 enum vtype tn_type;
116
117 /* Node identifier. */
118 ino_t tn_id;
119
120 /* Node's internal status. This is used by several file system
121 * operations to do modifications to the node in a delayed
122 * fashion. */
123 int tn_status;
124 #define TMPFS_NODE_ACCESSED (1 << 1)
125 #define TMPFS_NODE_MODIFIED (1 << 2)
126 #define TMPFS_NODE_CHANGED (1 << 3)
127
128 /* The node size. It does not necessarily match the real amount
129 * of memory consumed by it. */
130 off_t tn_size;
131
132 /* Generic node attributes. */
133 uid_t tn_uid;
134 gid_t tn_gid;
135 mode_t tn_mode;
136 int tn_flags;
137 nlink_t tn_links;
138 struct timespec tn_atime;
139 struct timespec tn_mtime;
140 struct timespec tn_ctime;
141 struct timespec tn_birthtime;
142 unsigned long tn_gen;
143
144 /* Head of byte-level lock list (used by tmpfs_advlock). */
145 struct lockf * tn_lockf;
146
147 /* As there is a single vnode for each active file within the
148 * system, care has to be taken to avoid allocating more than one
149 * vnode per file. In order to do this, a bidirectional association
150 * is kept between vnodes and nodes.
151 *
152 * Whenever a vnode is allocated, its v_data field is updated to
153 * point to the node it references. At the same time, the node's
154 * tn_vnode field is modified to point to the new vnode representing
155 * it. Further attempts to allocate a vnode for this same node will
156 * result in returning a new reference to the value stored in
157 * tn_vnode.
158 *
159 * May be NULL when the node is unused (that is, no vnode has been
160 * allocated for it or it has been reclaimed). */
161 struct vnode * tn_vnode;
162
163 /* Pointer to the node returned by tmpfs_lookup() after doing a
164 * delete or a rename lookup; its value is only valid in these two
165 * situations. In case we were looking up . or .., it holds a null
166 * pointer. */
167 struct tmpfs_dirent * tn_lookup_dirent;
168
169 union {
170 /* Valid when tn_type == VBLK || tn_type == VCHR. */
171 struct {
172 dev_t tn_rdev;
173 } tn_dev;
174
175 /* Valid when tn_type == VDIR. */
176 struct {
177 /* Pointer to the parent directory. The root
178 * directory has a pointer to itself in this field;
179 * this property identifies the root node. */
180 struct tmpfs_node * tn_parent;
181
182 /* Head of a tail-queue that links the contents of
183 * the directory together. See above for a
184 * description of its contents. */
185 struct tmpfs_dir tn_dir;
186
187 /* Number and pointer of the first directory entry
188 * returned by the readdir operation if it were
189 * called again to continue reading data from the
190 * same directory as before. This is used to speed
191 * up reads of long directories, assuming that no
192 * more than one read is in progress at a given time.
193 * Otherwise, these values are discarded and a linear
194 * scan is performed from the beginning up to the
195 * point where readdir starts returning values. */
196 off_t tn_readdir_lastn;
197 struct tmpfs_dirent * tn_readdir_lastp;
198 } tn_dir;
199
200 /* Valid when tn_type == VLNK. */
201 struct tn_lnk {
202 /* The link's target, allocated from a string pool. */
203 char * tn_link;
204 } tn_lnk;
205
206 /* Valid when tn_type == VREG. */
207 struct tn_reg {
208 /* The contents of regular files stored in a tmpfs
209 * file system are represented by a single anonymous
210 * memory object (aobj, for short). The aobj provides
211 * direct access to any position within the file,
212 * because its contents are always mapped in a
213 * contiguous region of virtual memory. It is a task
214 * of the memory management subsystem (see uvm(9)) to
215 * issue the required page ins or page outs whenever
216 * a position within the file is accessed. */
217 struct uvm_object * tn_aobj;
218 size_t tn_aobj_pages;
219 } tn_reg;
220 } tn_spec;
221 };
222
223 #if defined(_KERNEL)
224
225 LIST_HEAD(tmpfs_node_list, tmpfs_node);
226
227 /* --------------------------------------------------------------------- */
228
229 /*
230 * Internal representation of a tmpfs mount point.
231 */
232 struct tmpfs_mount {
233 /* Maximum number of memory pages available for use by the file
234 * system, set during mount time. This variable must never be
235 * used directly as it may be bigger that the current amount of
236 * free memory; in the extreme case, it will hold the SIZE_MAX
237 * value. Instead, use the TMPFS_PAGES_MAX macro. */
238 size_t tm_pages_max;
239
240 /* Number of pages in use by the file system. Cannot be bigger
241 * than the value returned by TMPFS_PAGES_MAX in any case. */
242 size_t tm_pages_used;
243
244 /* Pointer to the node representing the root directory of this
245 * file system. */
246 struct tmpfs_node * tm_root;
247
248 /* Maximum number of possible nodes for this file system; set
249 * during mount time. We need a hard limit on the maximum number
250 * of nodes to avoid allocating too much of them; their objects
251 * cannot be released until the file system is unmounted.
252 * Otherwise, we could easily run out of memory by creating lots
253 * of empty files and then simply removing them. */
254 ino_t tm_nodes_max;
255
256 /* Number of nodes currently allocated. This number only grows.
257 * When it reaches tm_nodes_max, no more new nodes can be allocated.
258 * Of course, the old, unused ones can be reused. */
259 ino_t tm_nodes_last;
260
261 /* Nodes are organized in two different lists. The used list
262 * contains all nodes that are currently used by the file system;
263 * i.e., they refer to existing files. The available list contains
264 * all nodes that are currently available for use by new files.
265 * Nodes must be kept in this list (instead of deleting them)
266 * because we need to keep track of their generation number (tn_gen
267 * field).
268 *
269 * Note that nodes are lazily allocated: if the available list is
270 * empty and we have enough space to create more nodes, they will be
271 * created and inserted in the used list. Once these are released,
272 * they will go into the available list, remaining alive until the
273 * file system is unmounted. */
274 struct tmpfs_node_list tm_nodes_used;
275 struct tmpfs_node_list tm_nodes_avail;
276
277 /* Pools used to store file system meta data. These are not shared
278 * across several instances of tmpfs for the reasons described in
279 * tmpfs_pool.c. */
280 struct tmpfs_pool tm_dirent_pool;
281 struct tmpfs_pool tm_node_pool;
282 struct tmpfs_str_pool tm_str_pool;
283 };
284
285 /* --------------------------------------------------------------------- */
286
287 /*
288 * This structure maps a file identifier to a tmpfs node. Used by the
289 * NFS code.
290 */
291 struct tmpfs_fid {
292 uint16_t tf_len;
293 uint16_t tf_pad;
294 uint32_t tf_gen;
295 ino_t tf_id;
296 };
297
298 /* --------------------------------------------------------------------- */
299
300 /*
301 * Prototypes for tmpfs_subr.c.
302 */
303
304 int tmpfs_alloc_node(struct tmpfs_mount *, enum vtype,
305 uid_t uid, gid_t gid, mode_t mode, struct tmpfs_node *,
306 char *, dev_t, struct proc *, struct tmpfs_node **);
307 void tmpfs_free_node(struct tmpfs_mount *, struct tmpfs_node *);
308 int tmpfs_alloc_dirent(struct tmpfs_mount *, struct tmpfs_node *,
309 const char *, uint16_t, struct tmpfs_dirent **);
310 void tmpfs_free_dirent(struct tmpfs_mount *, struct tmpfs_dirent *,
311 boolean_t);
312 int tmpfs_alloc_vp(struct mount *, struct tmpfs_node *, struct vnode **);
313 void tmpfs_free_vp(struct vnode *);
314 int tmpfs_alloc_file(struct vnode *, struct vnode **, struct vattr *,
315 struct componentname *, char *);
316 void tmpfs_dir_attach(struct vnode *, struct tmpfs_dirent *);
317 void tmpfs_dir_detach(struct vnode *, struct tmpfs_dirent *);
318 struct tmpfs_dirent * tmpfs_dir_lookup(struct tmpfs_node *node,
319 struct componentname *cnp);
320 int tmpfs_dir_getdotdent(struct tmpfs_node *, struct uio *);
321 int tmpfs_dir_getdotdotdent(struct tmpfs_node *, struct uio *);
322 struct tmpfs_dirent * tmpfs_dir_lookupbycookie(struct tmpfs_node *, off_t);
323 int tmpfs_dir_getdents(struct tmpfs_node *, struct uio *, off_t *);
324 int tmpfs_reg_resize(struct vnode *, off_t);
325 size_t tmpfs_mem_info(boolean_t);
326 int tmpfs_chflags(struct vnode *, int, kauth_cred_t, struct lwp *);
327 int tmpfs_chmod(struct vnode *, mode_t, kauth_cred_t, struct lwp *);
328 int tmpfs_chown(struct vnode *, uid_t, gid_t, kauth_cred_t, struct lwp *);
329 int tmpfs_chsize(struct vnode *, u_quad_t, kauth_cred_t, struct lwp *);
330 int tmpfs_chtimes(struct vnode *, struct timespec *, struct timespec *,
331 int, kauth_cred_t, struct lwp *);
332 void tmpfs_itimes(struct vnode *, const struct timespec *,
333 const struct timespec *);
334
335 void tmpfs_update(struct vnode *, const struct timespec *,
336 const struct timespec *, int);
337 int tmpfs_truncate(struct vnode *, off_t);
338
339 /* --------------------------------------------------------------------- */
340
341 /*
342 * Convenience macros to simplify some logical expressions.
343 */
344 #define IMPLIES(a, b) (!(a) || (b))
345 #define IFF(a, b) (IMPLIES(a, b) && IMPLIES(b, a))
346
347 /* --------------------------------------------------------------------- */
348
349 /*
350 * Checks that the directory entry pointed by 'de' matches the name 'name'
351 * with a length of 'len'.
352 */
353 #define TMPFS_DIRENT_MATCHES(de, name, len) \
354 (de->td_namelen == (uint16_t)len && \
355 memcmp((de)->td_name, (name), (de)->td_namelen) == 0)
356
357 /* --------------------------------------------------------------------- */
358
359 /*
360 * Ensures that the node pointed by 'node' is a directory and that its
361 * contents are consistent with respect to directories.
362 */
363 #define TMPFS_VALIDATE_DIR(node) \
364 KASSERT((node)->tn_type == VDIR); \
365 KASSERT((node)->tn_size % sizeof(struct tmpfs_dirent) == 0); \
366 KASSERT((node)->tn_spec.tn_dir.tn_readdir_lastp == NULL || \
367 TMPFS_DIRCOOKIE((node)->tn_spec.tn_dir.tn_readdir_lastp) == \
368 (node)->tn_spec.tn_dir.tn_readdir_lastn);
369
370 /* --------------------------------------------------------------------- */
371
372 /*
373 * Memory management stuff.
374 */
375
376 /* Amount of memory pages to reserve for the system (e.g., to not use by
377 * tmpfs).
378 * XXX: Should this be tunable through sysctl, for instance? */
379 #define TMPFS_PAGES_RESERVED (4 * 1024 * 1024 / PAGE_SIZE)
380
381 /* Returns the maximum size allowed for a tmpfs file system. This macro
382 * must be used instead of directly retrieving the value from tm_pages_max.
383 * The reason is that the size of a tmpfs file system is dynamic: it lets
384 * the user store files as long as there is enough free memory (including
385 * physical memory and swap space). Therefore, the amount of memory to be
386 * used is either the limit imposed by the user during mount time or the
387 * amount of available memory, whichever is lower. To avoid consuming all
388 * the memory for a given mount point, the system will always reserve a
389 * minimum of TMPFS_PAGES_RESERVED pages, which is also taken into account
390 * by this macro (see above). */
391 static __inline size_t
392 TMPFS_PAGES_MAX(struct tmpfs_mount *tmp)
393 {
394 size_t freepages;
395
396 freepages = tmpfs_mem_info(FALSE);
397 if (freepages < TMPFS_PAGES_RESERVED)
398 freepages = 0;
399 else
400 freepages -= TMPFS_PAGES_RESERVED;
401
402 return MIN(tmp->tm_pages_max, freepages + tmp->tm_pages_used);
403 }
404
405 /* Returns the available space for the given file system. */
406 #define TMPFS_PAGES_AVAIL(tmp) (TMPFS_PAGES_MAX(tmp) - (tmp)->tm_pages_used)
407
408 /* --------------------------------------------------------------------- */
409
410 /*
411 * Macros/functions to convert from generic data structures to tmpfs
412 * specific ones.
413 */
414
415 static __inline
416 struct tmpfs_mount *
417 VFS_TO_TMPFS(struct mount *mp)
418 {
419 struct tmpfs_mount *tmp;
420
421 #ifdef KASSERT
422 KASSERT((mp) != NULL && (mp)->mnt_data != NULL);
423 #endif
424 tmp = (struct tmpfs_mount *)(mp)->mnt_data;
425 return tmp;
426 }
427
428 #endif /* defined(_KERNEL) */
429
430 static __inline
431 struct tmpfs_node *
432 VP_TO_TMPFS_NODE(struct vnode *vp)
433 {
434 struct tmpfs_node *node;
435
436 #ifdef KASSERT
437 KASSERT((vp) != NULL && (vp)->v_data != NULL);
438 #endif
439 node = (struct tmpfs_node *)vp->v_data;
440 return node;
441 }
442
443 #if defined(_KERNEL)
444
445 static __inline
446 struct tmpfs_node *
447 VP_TO_TMPFS_DIR(struct vnode *vp)
448 {
449 struct tmpfs_node *node;
450
451 node = VP_TO_TMPFS_NODE(vp);
452 #ifdef KASSERT
453 TMPFS_VALIDATE_DIR(node);
454 #endif
455 return node;
456 }
457
458 #endif /* defined(_KERNEL) */
459
460 /* ---------------------------------------------------------------------
461 * USER AND KERNEL DEFINITIONS
462 * --------------------------------------------------------------------- */
463
464 /*
465 * This structure is used to communicate mount parameters between userland
466 * and kernel space.
467 */
468 #define TMPFS_ARGS_VERSION 1
469 struct tmpfs_args {
470 int ta_version;
471
472 /* Size counters. */
473 ino_t ta_nodes_max;
474 off_t ta_size_max;
475
476 /* Root node attributes. */
477 uid_t ta_root_uid;
478 gid_t ta_root_gid;
479 mode_t ta_root_mode;
480 };
481 #endif /* _FS_TMPFS_TMPFS_H_ */
482