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: stable/10/sys/fs/tmpfs/tmpfs.h 269175 2014-07-28 01:23:59Z kib $
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
52MALLOC_DECLARE(M_TMPFSMNT);
53MALLOC_DECLARE(M_TMPFSNAME);
54
55/*
56 * Internal representation of a tmpfs directory entry.
57 */
58
59LIST_HEAD(tmpfs_dir_duphead, tmpfs_dirent);
60
61struct 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 /* Pointer to the node this entry refers to. In case this field
84 * is NULL, the node is a whiteout. */
85 struct tmpfs_node * td_node;
86
87 union {
88 /*
89 * The name of the entry, allocated from a string pool. This
90 * string is not required to be zero-terminated.
91 */
92 char * td_name; /* regular, dup */
93 struct tmpfs_dir_duphead td_duphead; /* duphead */
94 } ud;
95};
96
97/* A directory in tmpfs holds a list of directory entries, which in
98 * turn point to other files (which can be directories themselves).
99 *
100 * In tmpfs, this list is managed by a RB-Tree, whose head is defined by
101 * the struct tmpfs_dir type.
102 *
103 * It is important to notice that directories do not have entries for . and
104 * .. as other file systems do. These can be generated when requested
105 * based on information available by other means, such as the pointer to
106 * the node itself in the former case or the pointer to the parent directory
107 * in the latter case. This is done to simplify tmpfs's code and, more
108 * importantly, to remove redundancy. */
109RB_HEAD(tmpfs_dir, tmpfs_dirent);
110
111/* Each entry in a directory has a cookie that identifies it. Cookies
112 * supersede offsets within directories because, given how tmpfs stores
113 * directories in memory, there is no such thing as an offset.
114 *
115 * The '.', '..' and the end of directory markers have fixed cookies which
116 * cannot collide with the cookies generated by other entries. The cookies
117 * for the other entries are generated based on the file name hash value or
118 * unique number in case of name hash collision.
119 *
120 * To preserve compatibility cookies are limited to 31 bits.
121 */
122
123#define TMPFS_DIRCOOKIE_DOT 0
124#define TMPFS_DIRCOOKIE_DOTDOT 1
125#define TMPFS_DIRCOOKIE_EOF 2
126#define TMPFS_DIRCOOKIE_MASK ((off_t)0x3fffffffU)
127#define TMPFS_DIRCOOKIE_MIN ((off_t)0x00000004U)
128#define TMPFS_DIRCOOKIE_DUP ((off_t)0x40000000U)
129#define TMPFS_DIRCOOKIE_DUPHEAD ((off_t)0x80000000U)
130#define TMPFS_DIRCOOKIE_DUP_MIN TMPFS_DIRCOOKIE_DUP
131#define TMPFS_DIRCOOKIE_DUP_MAX \
132 (TMPFS_DIRCOOKIE_DUP | TMPFS_DIRCOOKIE_MASK)
133
134/*
135 * Internal representation of a tmpfs file system node.
136 *
137 * This structure is splitted in two parts: one holds attributes common
138 * to all file types and the other holds data that is only applicable to
139 * a particular type. The code must be careful to only access those
140 * attributes that are actually allowed by the node's type.
141 *
142 *
143 * Below is the key of locks used to protected the fields in the following
144 * structures.
145 *
146 */
147struct tmpfs_node {
148 /* Doubly-linked list entry which links all existing nodes for a
149 * single file system. This is provided to ease the removal of
150 * all nodes during the unmount operation. */
151 LIST_ENTRY(tmpfs_node) tn_entries;
152
153 /* The node's type. Any of 'VBLK', 'VCHR', 'VDIR', 'VFIFO',
154 * 'VLNK', 'VREG' and 'VSOCK' is allowed. The usage of vnode
155 * types instead of a custom enumeration is to make things simpler
156 * and faster, as we do not need to convert between two types. */
157 enum vtype tn_type;
158
159 /* Node identifier. */
160 ino_t tn_id;
161
162 /* Node's internal status. This is used by several file system
163 * operations to do modifications to the node in a delayed
164 * fashion. */
165 int tn_status;
166#define TMPFS_NODE_ACCESSED (1 << 1)
167#define TMPFS_NODE_MODIFIED (1 << 2)
168#define TMPFS_NODE_CHANGED (1 << 3)
169
170 /* The node size. It does not necessarily match the real amount
171 * of memory consumed by it. */
172 off_t tn_size;
173
174 /* Generic node attributes. */
175 uid_t tn_uid;
176 gid_t tn_gid;
177 mode_t tn_mode;
178 u_long tn_flags;
179 nlink_t tn_links;
180 struct timespec tn_atime;
181 struct timespec tn_mtime;
182 struct timespec tn_ctime;
183 struct timespec tn_birthtime;
184 unsigned long tn_gen;
185
186 /* As there is a single vnode for each active file within the
187 * system, care has to be taken to avoid allocating more than one
188 * vnode per file. In order to do this, a bidirectional association
189 * is kept between vnodes and nodes.
190 *
191 * Whenever a vnode is allocated, its v_data field is updated to
192 * point to the node it references. At the same time, the node's
193 * tn_vnode field is modified to point to the new vnode representing
194 * it. Further attempts to allocate a vnode for this same node will
195 * result in returning a new reference to the value stored in
196 * tn_vnode.
197 *
198 * May be NULL when the node is unused (that is, no vnode has been
199 * allocated for it or it has been reclaimed). */
200 struct vnode * tn_vnode;
201
202 /* interlock to protect tn_vpstate */
203 struct mtx tn_interlock;
204
205 /* Identify if current node has vnode assiocate with
206 * or allocating vnode.
207 */
208 int tn_vpstate;
209
210 /* misc data field for different tn_type node */
211 union {
212 /* Valid when tn_type == VBLK || tn_type == VCHR. */
213 dev_t tn_rdev;
214
215 /* Valid when tn_type == VDIR. */
216 struct tn_dir {
217 /* Pointer to the parent directory. The root
218 * directory has a pointer to itself in this field;
219 * this property identifies the root node. */
220 struct tmpfs_node * tn_parent;
221
222 /* Head of a tree that links the contents of
223 * the directory together. */
224 struct tmpfs_dir tn_dirhead;
225
226 /* Head of a list the contains fake directory entries
227 * heads, i.e. entries with TMPFS_DIRCOOKIE_DUPHEAD
228 * flag. */
229 struct tmpfs_dir_duphead tn_dupindex;
230
231 /* Number and pointer of the first directory entry
232 * returned by the readdir operation if it were
233 * called again to continue reading data from the
234 * same directory as before. This is used to speed
235 * up reads of long directories, assuming that no
236 * more than one read is in progress at a given time.
237 * Otherwise, these values are discarded. */
238 off_t tn_readdir_lastn;
239 struct tmpfs_dirent * tn_readdir_lastp;
240 } tn_dir;
241
242 /* Valid when tn_type == VLNK. */
243 /* The link's target, allocated from a string pool. */
244 char * tn_link;
245
246 /* Valid when tn_type == VREG. */
247 struct tn_reg {
248 /* The contents of regular files stored in a tmpfs
249 * file system are represented by a single anonymous
250 * memory object (aobj, for short). The aobj provides
251 * direct access to any position within the file,
252 * because its contents are always mapped in a
253 * contiguous region of virtual memory. It is a task
254 * of the memory management subsystem (see uvm(9)) to
255 * issue the required page ins or page outs whenever
256 * a position within the file is accessed. */
257 vm_object_t tn_aobj;
258
259 }tn_reg;
260
261 /* Valid when tn_type = VFIFO */
262 struct tn_fifo {
263 fo_rdwr_t *tn_fo_read;
264 fo_rdwr_t *tn_fo_write;
265 }tn_fifo;
266 }tn_spec;
267};
268LIST_HEAD(tmpfs_node_list, tmpfs_node);
269
270#define tn_rdev tn_spec.tn_rdev
271#define tn_dir tn_spec.tn_dir
272#define tn_link tn_spec.tn_link
273#define tn_reg tn_spec.tn_reg
274#define tn_fifo tn_spec.tn_fifo
275
276#define TMPFS_NODE_LOCK(node) mtx_lock(&(node)->tn_interlock)
277#define TMPFS_NODE_UNLOCK(node) mtx_unlock(&(node)->tn_interlock)
278#define TMPFS_NODE_MTX(node) (&(node)->tn_interlock)
279#define TMPFS_NODE_ASSERT_LOCKED(node) mtx_assert(TMPFS_NODE_MTX(node), \
280 MA_OWNED)
281
282#ifdef INVARIANTS
283#define TMPFS_ASSERT_LOCKED(node) do { \
284 MPASS(node != NULL); \
285 MPASS(node->tn_vnode != NULL); \
286 if (!VOP_ISLOCKED(node->tn_vnode) && \
287 !mtx_owned(TMPFS_NODE_MTX(node))) \
288 panic("tmpfs: node is not locked: %p", node); \
289 } while (0)
290#define TMPFS_ASSERT_ELOCKED(node) do { \
291 MPASS((node) != NULL); \
292 MPASS((node)->tn_vnode != NULL); \
293 mtx_assert(TMPFS_NODE_MTX(node), MA_OWNED); \
294 ASSERT_VOP_LOCKED((node)->tn_vnode, "tmpfs"); \
295 } while (0)
296#else
297#define TMPFS_ASSERT_LOCKED(node) (void)0
298#define TMPFS_ASSERT_ELOCKED(node) (void)0
299#endif
300
301#define TMPFS_VNODE_ALLOCATING 1
302#define TMPFS_VNODE_WANT 2
303#define TMPFS_VNODE_DOOMED 4
304#define TMPFS_VNODE_WRECLAIM 8
305
306/*
307 * Internal representation of a tmpfs mount point.
308 */
309struct tmpfs_mount {
310 /* Maximum number of memory pages available for use by the file
311 * system, set during mount time. This variable must never be
312 * used directly as it may be bigger than the current amount of
313 * free memory; in the extreme case, it will hold the SIZE_MAX
314 * value. */
315 size_t tm_pages_max;
316
317 /* Number of pages in use by the file system. */
318 size_t tm_pages_used;
319
320 /* Pointer to the node representing the root directory of this
321 * file system. */
322 struct tmpfs_node * tm_root;
323
324 /* Maximum number of possible nodes for this file system; set
325 * during mount time. We need a hard limit on the maximum number
326 * of nodes to avoid allocating too much of them; their objects
327 * cannot be released until the file system is unmounted.
328 * Otherwise, we could easily run out of memory by creating lots
329 * of empty files and then simply removing them. */
330 ino_t tm_nodes_max;
331
332 /* unrhdr used to allocate inode numbers */
333 struct unrhdr * tm_ino_unr;
334
335 /* Number of nodes currently that are in use. */
336 ino_t tm_nodes_inuse;
337
338 /* maximum representable file size */
339 u_int64_t tm_maxfilesize;
340
341 /* Nodes are organized in two different lists. The used list
342 * contains all nodes that are currently used by the file system;
343 * i.e., they refer to existing files. The available list contains
344 * all nodes that are currently available for use by new files.
345 * Nodes must be kept in this list (instead of deleting them)
346 * because we need to keep track of their generation number (tn_gen
347 * field).
348 *
349 * Note that nodes are lazily allocated: if the available list is
350 * empty and we have enough space to create more nodes, they will be
351 * created and inserted in the used list. Once these are released,
352 * they will go into the available list, remaining alive until the
353 * file system is unmounted. */
354 struct tmpfs_node_list tm_nodes_used;
355
356 /* All node lock to protect the node list and tmp_pages_used */
357 struct mtx allnode_lock;
358
359 /* Pools used to store file system meta data. These are not shared
360 * across several instances of tmpfs for the reasons described in
361 * tmpfs_pool.c. */
362 uma_zone_t tm_dirent_pool;
363 uma_zone_t tm_node_pool;
364
365 /* Read-only status. */
366 int tm_ronly;
367};
368#define TMPFS_LOCK(tm) mtx_lock(&(tm)->allnode_lock)
369#define TMPFS_UNLOCK(tm) mtx_unlock(&(tm)->allnode_lock)
370
371/*
372 * This structure maps a file identifier to a tmpfs node. Used by the
373 * NFS code.
374 */
375struct tmpfs_fid {
376 uint16_t tf_len;
377 uint16_t tf_pad;
378 ino_t tf_id;
379 unsigned long tf_gen;
380};
381
382#ifdef _KERNEL
383/*
384 * Prototypes for tmpfs_subr.c.
385 */
386
387int tmpfs_alloc_node(struct mount *mp, struct tmpfs_mount *, enum vtype,
388 uid_t uid, gid_t gid, mode_t mode, struct tmpfs_node *,
389 char *, dev_t, struct tmpfs_node **);
390void tmpfs_free_node(struct tmpfs_mount *, struct tmpfs_node *);
391int tmpfs_alloc_dirent(struct tmpfs_mount *, struct tmpfs_node *,
392 const char *, u_int, struct tmpfs_dirent **);
393void tmpfs_free_dirent(struct tmpfs_mount *, struct tmpfs_dirent *);
394void tmpfs_dirent_init(struct tmpfs_dirent *, const char *, u_int);
395void tmpfs_destroy_vobject(struct vnode *vp, vm_object_t obj);
396int tmpfs_alloc_vp(struct mount *, struct tmpfs_node *, int,
397 struct vnode **);
398void tmpfs_free_vp(struct vnode *);
399int tmpfs_alloc_file(struct vnode *, struct vnode **, struct vattr *,
400 struct componentname *, char *);
401void tmpfs_dir_attach(struct vnode *, struct tmpfs_dirent *);
402void tmpfs_dir_detach(struct vnode *, struct tmpfs_dirent *);
403void tmpfs_dir_destroy(struct tmpfs_mount *, struct tmpfs_node *);
404struct tmpfs_dirent * tmpfs_dir_lookup(struct tmpfs_node *node,
405 struct tmpfs_node *f,
406 struct componentname *cnp);
407int tmpfs_dir_getdents(struct tmpfs_node *, struct uio *, int,
408 u_long *, int *);
409int tmpfs_dir_whiteout_add(struct vnode *, struct componentname *);
410void tmpfs_dir_whiteout_remove(struct vnode *, struct componentname *);
411int tmpfs_reg_resize(struct vnode *, off_t, boolean_t);
412int tmpfs_chflags(struct vnode *, u_long, struct ucred *, struct thread *);
413int tmpfs_chmod(struct vnode *, mode_t, struct ucred *, struct thread *);
414int tmpfs_chown(struct vnode *, uid_t, gid_t, struct ucred *,
415 struct thread *);
416int tmpfs_chsize(struct vnode *, u_quad_t, struct ucred *, struct thread *);
417int tmpfs_chtimes(struct vnode *, struct vattr *, struct ucred *cred,
418 struct thread *);
419void tmpfs_itimes(struct vnode *, const struct timespec *,
420 const struct timespec *);
421
422void tmpfs_update(struct vnode *);
423int tmpfs_truncate(struct vnode *, off_t);
424
425/*
426 * Convenience macros to simplify some logical expressions.
427 */
428#define IMPLIES(a, b) (!(a) || (b))
429#define IFF(a, b) (IMPLIES(a, b) && IMPLIES(b, a))
430
431/*
432 * Checks that the directory entry pointed by 'de' matches the name 'name'
433 * with a length of 'len'.
434 */
435#define TMPFS_DIRENT_MATCHES(de, name, len) \
436 (de->td_namelen == len && \
437 bcmp((de)->ud.td_name, (name), (de)->td_namelen) == 0)
438
439/*
440 * Ensures that the node pointed by 'node' is a directory and that its
441 * contents are consistent with respect to directories.
442 */
443#define TMPFS_VALIDATE_DIR(node) do { \
444 MPASS((node)->tn_type == VDIR); \
445 MPASS((node)->tn_size % sizeof(struct tmpfs_dirent) == 0); \
446} while (0)
447
448/*
449 * Memory management stuff.
450 */
451
452/*
453 * Amount of memory pages to reserve for the system (e.g., to not use by
454 * tmpfs).
455 */
456#define TMPFS_PAGES_MINRESERVED (4 * 1024 * 1024 / PAGE_SIZE)
457
458size_t tmpfs_mem_avail(void);
459
460size_t tmpfs_pages_used(struct tmpfs_mount *tmp);
461
462#endif
463
464/*
465 * Macros/functions to convert from generic data structures to tmpfs
466 * specific ones.
467 */
468
469static inline
470struct tmpfs_mount *
471VFS_TO_TMPFS(struct mount *mp)
472{
473 struct tmpfs_mount *tmp;
474
475 MPASS((mp) != NULL && (mp)->mnt_data != NULL);
476 tmp = (struct tmpfs_mount *)(mp)->mnt_data;
477 return tmp;
478}
479
480static inline
481struct tmpfs_node *
482VP_TO_TMPFS_NODE(struct vnode *vp)
483{
484 struct tmpfs_node *node;
485
486 MPASS((vp) != NULL && (vp)->v_data != NULL);
487 node = (struct tmpfs_node *)vp->v_data;
488 return node;
489}
490
491static inline
492struct tmpfs_node *
493VP_TO_TMPFS_DIR(struct vnode *vp)
494{
495 struct tmpfs_node *node;
496
497 node = VP_TO_TMPFS_NODE(vp);
498 TMPFS_VALIDATE_DIR(node);
499 return node;
500}
501
502#endif /* _FS_TMPFS_TMPFS_H_ */