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 * $FreeBSD$
33 */
34
35 #ifndef _FS_TMPFS_TMPFS_H_
36 #define _FS_TMPFS_TMPFS_H_
37
38 #include <sys/dirent.h>
39 #include <sys/mount.h>
40 #include <sys/queue.h>
41 #include <sys/vnode.h>
42 #include <sys/file.h>
43 #include <sys/lock.h>
44 #include <sys/mutex.h>
45
46 #include <sys/malloc.h>
47 #include <sys/systm.h>
48 #include <sys/tree.h>
49 #include <sys/vmmeter.h>
50 #include <vm/swap_pager.h>
51
52 MALLOC_DECLARE(M_TMPFSMNT);
53 MALLOC_DECLARE(M_TMPFSNAME);
54
55 /*
56 * Internal representation of a tmpfs directory entry.
57 */
58
59 LIST_HEAD(tmpfs_dir_duphead, tmpfs_dirent);
60
61 struct tmpfs_dirent {
62 /*
63 * Depending on td_cookie flag entry can be of 3 types:
64 * - regular -- no hash collisions, stored in RB-Tree
65 * - duphead -- synthetic linked list head for dup entries
66 * - dup -- stored in linked list instead of RB-Tree
67 */
68 union {
69 /* regular and duphead entry types */
70 RB_ENTRY(tmpfs_dirent) td_entries;
71
72 /* dup entry type */
73 struct {
74 LIST_ENTRY(tmpfs_dirent) entries;
75 LIST_ENTRY(tmpfs_dirent) index_entries;
76 } td_dup;
77 } uh;
78
79 uint32_t td_cookie;
80 uint32_t td_hash;
81 u_int td_namelen;
82
83 /*
84 * Pointer to the node this entry refers to. In case this field
85 * is NULL, the node is a whiteout.
86 */
87 struct tmpfs_node * td_node;
88
89 union {
90 /*
91 * The name of the entry, allocated from a string pool. This
92 * string is not required to be zero-terminated.
93 */
94 char * td_name; /* regular, dup */
95 struct tmpfs_dir_duphead td_duphead; /* duphead */
96 } ud;
97 };
98
99 /*
100 * A directory in tmpfs holds a collection of directory entries, which
101 * in turn point to other files (which can be directories themselves).
102 *
103 * In tmpfs, this collection is managed by a RB-Tree, whose head is
104 * defined by the struct tmpfs_dir type.
105 *
106 * It is important to notice that directories do not have entries for . and
107 * .. as other file systems do. These can be generated when requested
108 * based on information available by other means, such as the pointer to
109 * the node itself in the former case or the pointer to the parent directory
110 * in the latter case. This is done to simplify tmpfs's code and, more
111 * importantly, to remove redundancy.
112 */
113 RB_HEAD(tmpfs_dir, tmpfs_dirent);
114
115 /*
116 * Each entry in a directory has a cookie that identifies it. Cookies
117 * supersede offsets within directories because, given how tmpfs stores
118 * directories in memory, there is no such thing as an offset.
119 *
120 * The '.', '..' and the end of directory markers have fixed cookies which
121 * cannot collide with the cookies generated by other entries. The cookies
122 * for the other entries are generated based on the file name hash value or
123 * unique number in case of name hash collision.
124 *
125 * To preserve compatibility cookies are limited to 31 bits.
126 */
127
128 #define TMPFS_DIRCOOKIE_DOT 0
129 #define TMPFS_DIRCOOKIE_DOTDOT 1
130 #define TMPFS_DIRCOOKIE_EOF 2
131 #define TMPFS_DIRCOOKIE_MASK ((off_t)0x3fffffffU)
132 #define TMPFS_DIRCOOKIE_MIN ((off_t)0x00000004U)
133 #define TMPFS_DIRCOOKIE_DUP ((off_t)0x40000000U)
134 #define TMPFS_DIRCOOKIE_DUPHEAD ((off_t)0x80000000U)
135 #define TMPFS_DIRCOOKIE_DUP_MIN TMPFS_DIRCOOKIE_DUP
136 #define TMPFS_DIRCOOKIE_DUP_MAX \
137 (TMPFS_DIRCOOKIE_DUP | TMPFS_DIRCOOKIE_MASK)
138
139 /*
140 * Internal representation of a tmpfs file system node.
141 *
142 * This structure is splitted in two parts: one holds attributes common
143 * to all file types and the other holds data that is only applicable to
144 * a particular type. The code must be careful to only access those
145 * attributes that are actually allowed by the node's type.
146 *
147 * Below is the key of locks used to protected the fields in the following
148 * structures.
149 * (v) vnode lock in exclusive mode
150 * (vi) vnode lock in exclusive mode, or vnode lock in shared vnode and
151 * tn_interlock
152 * (i) tn_interlock
153 * (m) tmpfs_mount tm_allnode_lock
154 * (c) stable after creation
155 */
156 struct tmpfs_node {
157 /*
158 * Doubly-linked list entry which links all existing nodes for
159 * a single file system. This is provided to ease the removal
160 * of all nodes during the unmount operation, and to support
161 * the implementation of VOP_VNTOCNP(). tn_attached is false
162 * when the node is removed from list and unlocked.
163 */
164 LIST_ENTRY(tmpfs_node) tn_entries; /* (m) */
165 bool tn_attached; /* (m) */
166
167 /*
168 * The node's type. Any of 'VBLK', 'VCHR', 'VDIR', 'VFIFO',
169 * 'VLNK', 'VREG' and 'VSOCK' is allowed. The usage of vnode
170 * types instead of a custom enumeration is to make things simpler
171 * and faster, as we do not need to convert between two types.
172 */
173 enum vtype tn_type; /* (c) */
174
175 /* Node identifier. */
176 ino_t tn_id; /* (c) */
177
178 /*
179 * Node's internal status. This is used by several file system
180 * operations to do modifications to the node in a delayed
181 * fashion.
182 */
183 int tn_status; /* (vi) */
184 #define TMPFS_NODE_ACCESSED (1 << 1)
185 #define TMPFS_NODE_MODIFIED (1 << 2)
186 #define TMPFS_NODE_CHANGED (1 << 3)
187
188 /*
189 * The node size. It does not necessarily match the real amount
190 * of memory consumed by it.
191 */
192 off_t tn_size; /* (v) */
193
194 /* Generic node attributes. */
195 uid_t tn_uid; /* (v) */
196 gid_t tn_gid; /* (v) */
197 mode_t tn_mode; /* (v) */
198 u_long tn_flags; /* (v) */
199 nlink_t tn_links; /* (v) */
200 struct timespec tn_atime; /* (vi) */
201 struct timespec tn_mtime; /* (vi) */
202 struct timespec tn_ctime; /* (vi) */
203 struct timespec tn_birthtime; /* (v) */
204 unsigned long tn_gen; /* (c) */
205
206 /*
207 * As there is a single vnode for each active file within the
208 * system, care has to be taken to avoid allocating more than one
209 * vnode per file. In order to do this, a bidirectional association
210 * is kept between vnodes and nodes.
211 *
212 * Whenever a vnode is allocated, its v_data field is updated to
213 * point to the node it references. At the same time, the node's
214 * tn_vnode field is modified to point to the new vnode representing
215 * it. Further attempts to allocate a vnode for this same node will
216 * result in returning a new reference to the value stored in
217 * tn_vnode.
218 *
219 * May be NULL when the node is unused (that is, no vnode has been
220 * allocated for it or it has been reclaimed).
221 */
222 struct vnode * tn_vnode; /* (i) */
223
224 /*
225 * Interlock to protect tn_vpstate, and tn_status under shared
226 * vnode lock.
227 */
228 struct mtx tn_interlock;
229
230 /*
231 * Identify if current node has vnode assiocate with
232 * or allocating vnode.
233 */
234 int tn_vpstate; /* (i) */
235
236 /* Transient refcounter on this node. */
237 u_int tn_refcount; /* (m) + (i) */
238
239 /* misc data field for different tn_type node */
240 union {
241 /* Valid when tn_type == VBLK || tn_type == VCHR. */
242 dev_t tn_rdev; /* (c) */
243
244 /* Valid when tn_type == VDIR. */
245 struct tn_dir {
246 /*
247 * Pointer to the parent directory. The root
248 * directory has a pointer to itself in this field;
249 * this property identifies the root node.
250 */
251 struct tmpfs_node * tn_parent;
252
253 /*
254 * Head of a tree that links the contents of
255 * the directory together.
256 */
257 struct tmpfs_dir tn_dirhead;
258
259 /*
260 * Head of a list the contains fake directory entries
261 * heads, i.e. entries with TMPFS_DIRCOOKIE_DUPHEAD
262 * flag.
263 */
264 struct tmpfs_dir_duphead tn_dupindex;
265
266 /*
267 * Number and pointer of the first directory entry
268 * returned by the readdir operation if it were
269 * called again to continue reading data from the
270 * same directory as before. This is used to speed
271 * up reads of long directories, assuming that no
272 * more than one read is in progress at a given time.
273 * Otherwise, these values are discarded.
274 */
275 off_t tn_readdir_lastn;
276 struct tmpfs_dirent * tn_readdir_lastp;
277 } tn_dir;
278
279 /* Valid when tn_type == VLNK. */
280 /* The link's target, allocated from a string pool. */
281 char * tn_link; /* (c) */
282
283 /* Valid when tn_type == VREG. */
284 struct tn_reg {
285 /*
286 * The contents of regular files stored in a
287 * tmpfs file system are represented by a
288 * single anonymous memory object (aobj, for
289 * short). The aobj provides direct access to
290 * any position within the file. It is a task
291 * of the memory management subsystem to issue
292 * the required page ins or page outs whenever
293 * a position within the file is accessed.
294 */
295 vm_object_t tn_aobj; /* (c) */
296 } tn_reg;
297 } tn_spec; /* (v) */
298 };
299 LIST_HEAD(tmpfs_node_list, tmpfs_node);
300
301 #define tn_rdev tn_spec.tn_rdev
302 #define tn_dir tn_spec.tn_dir
303 #define tn_link tn_spec.tn_link
304 #define tn_reg tn_spec.tn_reg
305 #define tn_fifo tn_spec.tn_fifo
306
307 #define TMPFS_NODE_LOCK(node) mtx_lock(&(node)->tn_interlock)
308 #define TMPFS_NODE_UNLOCK(node) mtx_unlock(&(node)->tn_interlock)
309 #define TMPFS_NODE_MTX(node) (&(node)->tn_interlock)
310 #define TMPFS_NODE_ASSERT_LOCKED(node) mtx_assert(TMPFS_NODE_MTX(node), \
311 MA_OWNED)
312
313 #ifdef INVARIANTS
314 #define TMPFS_ASSERT_LOCKED(node) do { \
315 MPASS((node) != NULL); \
316 MPASS((node)->tn_vnode != NULL); \
317 ASSERT_VOP_LOCKED((node)->tn_vnode, "tmpfs assert"); \
318 } while (0)
319 #else
320 #define TMPFS_ASSERT_LOCKED(node) (void)0
321 #endif
322
323 #define TMPFS_VNODE_ALLOCATING 1
324 #define TMPFS_VNODE_WANT 2
325 #define TMPFS_VNODE_DOOMED 4
326 #define TMPFS_VNODE_WRECLAIM 8
327
328 /*
329 * Internal representation of a tmpfs mount point.
330 */
331 struct tmpfs_mount {
332 /*
333 * Original value of the "size" parameter, for reference purposes,
334 * mostly.
335 */
336 off_t tm_size_max;
337 /*
338 * Maximum number of memory pages available for use by the file
339 * system, set during mount time. This variable must never be
340 * used directly as it may be bigger than the current amount of
341 * free memory; in the extreme case, it will hold the ULONG_MAX
342 * value.
343 */
344 u_long tm_pages_max;
345
346 /* Number of pages in use by the file system. */
347 u_long tm_pages_used;
348
349 /*
350 * Pointer to the node representing the root directory of this
351 * file system.
352 */
353 struct tmpfs_node * tm_root;
354
355 /*
356 * Maximum number of possible nodes for this file system; set
357 * during mount time. We need a hard limit on the maximum number
358 * of nodes to avoid allocating too much of them; their objects
359 * cannot be released until the file system is unmounted.
360 * Otherwise, we could easily run out of memory by creating lots
361 * of empty files and then simply removing them.
362 */
363 ino_t tm_nodes_max;
364
365 /* unrhdr used to allocate inode numbers */
366 struct unrhdr * tm_ino_unr;
367
368 /* Number of nodes currently that are in use. */
369 ino_t tm_nodes_inuse;
370
371 /* Refcounter on this struct tmpfs_mount. */
372 uint64_t tm_refcount;
373
374 /* maximum representable file size */
375 u_int64_t tm_maxfilesize;
376
377 /*
378 * The used list contains all nodes that are currently used by
379 * the file system; i.e., they refer to existing files.
380 */
381 struct tmpfs_node_list tm_nodes_used;
382
383 /* All node lock to protect the node list and tmp_pages_used. */
384 struct mtx tm_allnode_lock;
385
386 /* Zones used to store file system meta data, per tmpfs mount. */
387 uma_zone_t tm_dirent_pool;
388 uma_zone_t tm_node_pool;
389
390 /* Read-only status. */
391 bool tm_ronly;
392 /* Do not use namecache. */
393 bool tm_nonc;
394 };
395 #define TMPFS_LOCK(tm) mtx_lock(&(tm)->tm_allnode_lock)
396 #define TMPFS_UNLOCK(tm) mtx_unlock(&(tm)->tm_allnode_lock)
397 #define TMPFS_MP_ASSERT_LOCKED(tm) mtx_assert(&(tm)->tm_allnode_lock, MA_OWNED)
398
399 /*
400 * This structure maps a file identifier to a tmpfs node. Used by the
401 * NFS code.
402 */
403 struct tmpfs_fid {
404 uint16_t tf_len;
405 uint16_t tf_pad;
406 ino_t tf_id;
407 unsigned long tf_gen;
408 };
409
410 struct tmpfs_dir_cursor {
411 struct tmpfs_dirent *tdc_current;
412 struct tmpfs_dirent *tdc_tree;
413 };
414
415 #ifdef _KERNEL
416 /*
417 * Prototypes for tmpfs_subr.c.
418 */
419
420 void tmpfs_ref_node(struct tmpfs_node *node);
421 void tmpfs_ref_node_locked(struct tmpfs_node *node);
422 int tmpfs_alloc_node(struct mount *mp, struct tmpfs_mount *, enum vtype,
423 uid_t uid, gid_t gid, mode_t mode, struct tmpfs_node *,
424 char *, dev_t, struct tmpfs_node **);
425 void tmpfs_free_node(struct tmpfs_mount *, struct tmpfs_node *);
426 bool tmpfs_free_node_locked(struct tmpfs_mount *, struct tmpfs_node *, bool);
427 void tmpfs_free_tmp(struct tmpfs_mount *);
428 int tmpfs_alloc_dirent(struct tmpfs_mount *, struct tmpfs_node *,
429 const char *, u_int, struct tmpfs_dirent **);
430 void tmpfs_free_dirent(struct tmpfs_mount *, struct tmpfs_dirent *);
431 void tmpfs_dirent_init(struct tmpfs_dirent *, const char *, u_int);
432 void tmpfs_destroy_vobject(struct vnode *vp, vm_object_t obj);
433 int tmpfs_alloc_vp(struct mount *, struct tmpfs_node *, int,
434 struct vnode **);
435 void tmpfs_free_vp(struct vnode *);
436 int tmpfs_alloc_file(struct vnode *, struct vnode **, struct vattr *,
437 struct componentname *, char *);
438 void tmpfs_check_mtime(struct vnode *);
439 void tmpfs_dir_attach(struct vnode *, struct tmpfs_dirent *);
440 void tmpfs_dir_detach(struct vnode *, struct tmpfs_dirent *);
441 void tmpfs_dir_destroy(struct tmpfs_mount *, struct tmpfs_node *);
442 struct tmpfs_dirent * tmpfs_dir_lookup(struct tmpfs_node *node,
443 struct tmpfs_node *f,
444 struct componentname *cnp);
445 int tmpfs_dir_getdents(struct tmpfs_mount *, struct tmpfs_node *,
446 struct uio *, int, u_long *, int *);
447 int tmpfs_dir_whiteout_add(struct vnode *, struct componentname *);
448 void tmpfs_dir_whiteout_remove(struct vnode *, struct componentname *);
449 int tmpfs_reg_resize(struct vnode *, off_t, boolean_t);
450 int tmpfs_chflags(struct vnode *, u_long, struct ucred *, struct thread *);
451 int tmpfs_chmod(struct vnode *, mode_t, struct ucred *, struct thread *);
452 int tmpfs_chown(struct vnode *, uid_t, gid_t, struct ucred *,
453 struct thread *);
454 int tmpfs_chsize(struct vnode *, u_quad_t, struct ucred *, struct thread *);
455 int tmpfs_chtimes(struct vnode *, struct vattr *, struct ucred *cred,
456 struct thread *);
457 void tmpfs_itimes(struct vnode *, const struct timespec *,
458 const struct timespec *);
459
460 void tmpfs_set_status(struct tmpfs_mount *tm, struct tmpfs_node *node,
461 int status);
462 void tmpfs_update(struct vnode *);
463 int tmpfs_truncate(struct vnode *, off_t);
464 struct tmpfs_dirent *tmpfs_dir_first(struct tmpfs_node *dnode,
465 struct tmpfs_dir_cursor *dc);
466 struct tmpfs_dirent *tmpfs_dir_next(struct tmpfs_node *dnode,
467 struct tmpfs_dir_cursor *dc);
468
469 /*
470 * Convenience macros to simplify some logical expressions.
471 */
472 #define IMPLIES(a, b) (!(a) || (b))
473 #define IFF(a, b) (IMPLIES(a, b) && IMPLIES(b, a))
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 == len && \
481 bcmp((de)->ud.td_name, (name), (de)->td_namelen) == 0)
482
483 /*
484 * Ensures that the node pointed by 'node' is a directory and that its
485 * contents are consistent with respect to directories.
486 */
487 #define TMPFS_VALIDATE_DIR(node) do { \
488 MPASS((node)->tn_type == VDIR); \
489 MPASS((node)->tn_size % sizeof(struct tmpfs_dirent) == 0); \
490 } while (0)
491
492 /*
493 * Amount of memory pages to reserve for the system (e.g., to not use by
494 * tmpfs).
495 */
496 #define TMPFS_PAGES_MINRESERVED (4 * 1024 * 1024 / PAGE_SIZE)
497
498 size_t tmpfs_mem_avail(void);
499
500 size_t tmpfs_pages_used(struct tmpfs_mount *tmp);
501
502 /*
503 * Macros/functions to convert from generic data structures to tmpfs
504 * specific ones.
505 */
506
507 static inline struct tmpfs_mount *
VFS_TO_TMPFS(struct mount * mp)508 VFS_TO_TMPFS(struct mount *mp)
509 {
510 struct tmpfs_mount *tmp;
511
512 MPASS(mp != NULL && mp->mnt_data != NULL);
513 tmp = (struct tmpfs_mount *)mp->mnt_data;
514 return (tmp);
515 }
516
517 static inline struct tmpfs_node *
VP_TO_TMPFS_NODE(struct vnode * vp)518 VP_TO_TMPFS_NODE(struct vnode *vp)
519 {
520 struct tmpfs_node *node;
521
522 MPASS(vp != NULL && vp->v_data != NULL);
523 node = (struct tmpfs_node *)vp->v_data;
524 return (node);
525 }
526
527 static inline struct tmpfs_node *
VP_TO_TMPFS_DIR(struct vnode * vp)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 static inline bool
tmpfs_use_nc(struct vnode * vp)538 tmpfs_use_nc(struct vnode *vp)
539 {
540
541 return (!(VFS_TO_TMPFS(vp->v_mount)->tm_nonc));
542 }
543 #endif /* _KERNEL */
544
545 #endif /* _FS_TMPFS_TMPFS_H_ */
546