1 /* $NetBSD: tmpfs.h,v 1.26 2007/02/22 06:37:00 thorpej Exp $ */
4 * SPDX-License-Identifier: BSD-2-Clause-NetBSD
6 * Copyright (c) 2005, 2006 The NetBSD Foundation, Inc.
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
13 * Redistribution and use in source and binary forms, with or without
14 * modification, are permitted provided that the following conditions
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.
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.
37 #ifndef _FS_TMPFS_TMPFS_H_
38 #define _FS_TMPFS_TMPFS_H_
40 #include <sys/cdefs.h>
41 #include <sys/queue.h>
45 MALLOC_DECLARE(M_TMPFSNAME);
48 #define OBJ_TMPFS OBJ_PAGERPRIV1 /* has tmpfs vnode allocated */
49 #define OBJ_TMPFS_VREF OBJ_PAGERPRIV2 /* vnode is referenced */
52 * Internal representation of a tmpfs directory entry.
55 LIST_HEAD(tmpfs_dir_duphead, tmpfs_dirent);
59 * Depending on td_cookie flag entry can be of 3 types:
60 * - regular -- no hash collisions, stored in RB-Tree
61 * - duphead -- synthetic linked list head for dup entries
62 * - dup -- stored in linked list instead of RB-Tree
65 /* regular and duphead entry types */
66 RB_ENTRY(tmpfs_dirent) td_entries;
70 LIST_ENTRY(tmpfs_dirent) entries;
71 LIST_ENTRY(tmpfs_dirent) index_entries;
80 * Pointer to the node this entry refers to. In case this field
81 * is NULL, the node is a whiteout.
83 struct tmpfs_node * td_node;
87 * The name of the entry, allocated from a string pool. This
88 * string is not required to be zero-terminated.
90 char * td_name; /* regular, dup */
91 struct tmpfs_dir_duphead td_duphead; /* duphead */
96 * A directory in tmpfs holds a collection of directory entries, which
97 * in turn point to other files (which can be directories themselves).
99 * In tmpfs, this collection is managed by a RB-Tree, whose head is
100 * defined by the struct tmpfs_dir type.
102 * It is important to notice that directories do not have entries for . and
103 * .. as other file systems do. These can be generated when requested
104 * based on information available by other means, such as the pointer to
105 * the node itself in the former case or the pointer to the parent directory
106 * in the latter case. This is done to simplify tmpfs's code and, more
107 * importantly, to remove redundancy.
109 RB_HEAD(tmpfs_dir, tmpfs_dirent);
112 * Each entry in a directory has a cookie that identifies it. Cookies
113 * supersede offsets within directories because, given how tmpfs stores
114 * directories in memory, there is no such thing as an offset.
116 * The '.', '..' and the end of directory markers have fixed cookies which
117 * cannot collide with the cookies generated by other entries. The cookies
118 * for the other entries are generated based on the file name hash value or
119 * unique number in case of name hash collision.
121 * To preserve compatibility cookies are limited to 31 bits.
124 #define TMPFS_DIRCOOKIE_DOT 0
125 #define TMPFS_DIRCOOKIE_DOTDOT 1
126 #define TMPFS_DIRCOOKIE_EOF 2
127 #define TMPFS_DIRCOOKIE_MASK ((off_t)0x3fffffffU)
128 #define TMPFS_DIRCOOKIE_MIN ((off_t)0x00000004U)
129 #define TMPFS_DIRCOOKIE_DUP ((off_t)0x40000000U)
130 #define TMPFS_DIRCOOKIE_DUPHEAD ((off_t)0x80000000U)
131 #define TMPFS_DIRCOOKIE_DUP_MIN TMPFS_DIRCOOKIE_DUP
132 #define TMPFS_DIRCOOKIE_DUP_MAX \
133 (TMPFS_DIRCOOKIE_DUP | TMPFS_DIRCOOKIE_MASK)
136 * Internal representation of a tmpfs file system node.
138 * This structure is splitted in two parts: one holds attributes common
139 * to all file types and the other holds data that is only applicable to
140 * a particular type. The code must be careful to only access those
141 * attributes that are actually allowed by the node's type.
143 * Below is the key of locks used to protected the fields in the following
145 * (v) vnode lock in exclusive mode
146 * (vi) vnode lock in exclusive mode, or vnode lock in shared vnode and
149 * (m) tmpfs_mount tm_allnode_lock
150 * (c) stable after creation
154 * Doubly-linked list entry which links all existing nodes for
155 * a single file system. This is provided to ease the removal
156 * of all nodes during the unmount operation, and to support
157 * the implementation of VOP_VNTOCNP(). tn_attached is false
158 * when the node is removed from list and unlocked.
160 LIST_ENTRY(tmpfs_node) tn_entries; /* (m) */
162 /* Node identifier. */
163 ino_t tn_id; /* (c) */
166 * The node's type. Any of 'VBLK', 'VCHR', 'VDIR', 'VFIFO',
167 * 'VLNK', 'VREG' and 'VSOCK' is allowed. The usage of vnode
168 * types instead of a custom enumeration is to make things simpler
169 * and faster, as we do not need to convert between two types.
171 enum vtype tn_type; /* (c) */
174 * See the top comment. Reordered here to fill LP64 hole.
176 bool tn_attached; /* (m) */
179 * Node's internal status. This is used by several file system
180 * operations to do modifications to the node in a delayed
183 * tn_accessed has a dedicated byte to allow update by store without
184 * using atomics. This provides a micro-optimization to e.g.
185 * tmpfs_read_pgcache().
187 uint8_t tn_status; /* (vi) */
188 uint8_t tn_accessed; /* unlocked */
191 * The node size. It does not necessarily match the real amount
192 * of memory consumed by it.
194 off_t tn_size; /* (v) */
196 /* Generic node attributes. */
197 uid_t tn_uid; /* (v) */
198 gid_t tn_gid; /* (v) */
199 mode_t tn_mode; /* (v) */
200 int tn_links; /* (v) */
201 u_long tn_flags; /* (v) */
202 struct timespec tn_atime; /* (vi) */
203 struct timespec tn_mtime; /* (vi) */
204 struct timespec tn_ctime; /* (vi) */
205 struct timespec tn_birthtime; /* (v) */
206 unsigned long tn_gen; /* (c) */
209 * As there is a single vnode for each active file within the
210 * system, care has to be taken to avoid allocating more than one
211 * vnode per file. In order to do this, a bidirectional association
212 * is kept between vnodes and nodes.
214 * Whenever a vnode is allocated, its v_data field is updated to
215 * point to the node it references. At the same time, the node's
216 * tn_vnode field is modified to point to the new vnode representing
217 * it. Further attempts to allocate a vnode for this same node will
218 * result in returning a new reference to the value stored in
221 * May be NULL when the node is unused (that is, no vnode has been
222 * allocated for it or it has been reclaimed).
224 struct vnode * tn_vnode; /* (i) */
227 * Interlock to protect tn_vpstate, and tn_status under shared
230 struct mtx tn_interlock;
233 * Identify if current node has vnode assiocate with
234 * or allocating vnode.
236 int tn_vpstate; /* (i) */
238 /* Transient refcounter on this node. */
239 u_int tn_refcount; /* 0<->1 (m) + (i) */
241 /* misc data field for different tn_type node */
243 /* Valid when tn_type == VBLK || tn_type == VCHR. */
244 dev_t tn_rdev; /* (c) */
246 /* Valid when tn_type == VDIR. */
249 * Pointer to the parent directory. The root
250 * directory has a pointer to itself in this field;
251 * this property identifies the root node.
253 struct tmpfs_node * tn_parent;
256 * Head of a tree that links the contents of
257 * the directory together.
259 struct tmpfs_dir tn_dirhead;
262 * Head of a list the contains fake directory entries
263 * heads, i.e. entries with TMPFS_DIRCOOKIE_DUPHEAD
266 struct tmpfs_dir_duphead tn_dupindex;
269 * Number and pointer of the first directory entry
270 * returned by the readdir operation if it were
271 * called again to continue reading data from the
272 * same directory as before. This is used to speed
273 * up reads of long directories, assuming that no
274 * more than one read is in progress at a given time.
275 * Otherwise, these values are discarded.
277 off_t tn_readdir_lastn;
278 struct tmpfs_dirent * tn_readdir_lastp;
281 /* Valid when tn_type == VLNK. */
282 /* The link's target, allocated from a string pool. */
284 char * tn_link_target; /* (c) */
285 char tn_link_smr; /* (c) */
288 /* Valid when tn_type == VREG. */
291 * The contents of regular files stored in a
292 * tmpfs file system are represented by a
293 * single anonymous memory object (aobj, for
294 * short). The aobj provides direct access to
295 * any position within the file. It is a task
296 * of the memory management subsystem to issue
297 * the required page ins or page outs whenever
298 * a position within the file is accessed.
300 vm_object_t tn_aobj; /* (c) */
301 struct tmpfs_mount *tn_tmp; /* (c) */
305 LIST_HEAD(tmpfs_node_list, tmpfs_node);
307 #define tn_rdev tn_spec.tn_rdev
308 #define tn_dir tn_spec.tn_dir
309 #define tn_link_target tn_spec.tn_link.tn_link_target
310 #define tn_link_smr tn_spec.tn_link.tn_link_smr
311 #define tn_reg tn_spec.tn_reg
312 #define tn_fifo tn_spec.tn_fifo
314 #define TMPFS_LINK_MAX INT_MAX
316 #define TMPFS_NODE_LOCK(node) mtx_lock(&(node)->tn_interlock)
317 #define TMPFS_NODE_UNLOCK(node) mtx_unlock(&(node)->tn_interlock)
318 #define TMPFS_NODE_MTX(node) (&(node)->tn_interlock)
319 #define TMPFS_NODE_ASSERT_LOCKED(node) mtx_assert(TMPFS_NODE_MTX(node), \
323 #define TMPFS_ASSERT_LOCKED(node) do { \
324 MPASS((node) != NULL); \
325 MPASS((node)->tn_vnode != NULL); \
326 ASSERT_VOP_LOCKED((node)->tn_vnode, "tmpfs assert"); \
329 #define TMPFS_ASSERT_LOCKED(node) (void)0
333 #define TMPFS_VNODE_ALLOCATING 1
334 #define TMPFS_VNODE_WANT 2
335 #define TMPFS_VNODE_DOOMED 4
336 #define TMPFS_VNODE_WRECLAIM 8
339 #define TMPFS_NODE_MODIFIED 0x01
340 #define TMPFS_NODE_CHANGED 0x02
343 * Internal representation of a tmpfs mount point.
347 * Original value of the "size" parameter, for reference purposes,
352 * Maximum number of memory pages available for use by the file
353 * system, set during mount time. This variable must never be
354 * used directly as it may be bigger than the current amount of
355 * free memory; in the extreme case, it will hold the ULONG_MAX
360 /* Number of pages in use by the file system. */
361 u_long tm_pages_used;
364 * Pointer to the node representing the root directory of this
367 struct tmpfs_node * tm_root;
370 * Maximum number of possible nodes for this file system; set
371 * during mount time. We need a hard limit on the maximum number
372 * of nodes to avoid allocating too much of them; their objects
373 * cannot be released until the file system is unmounted.
374 * Otherwise, we could easily run out of memory by creating lots
375 * of empty files and then simply removing them.
379 /* unrhdr used to allocate inode numbers */
380 struct unrhdr64 tm_ino_unr;
382 /* Number of nodes currently that are in use. */
383 ino_t tm_nodes_inuse;
385 /* Refcounter on this struct tmpfs_mount. */
386 uint64_t tm_refcount;
388 /* maximum representable file size */
389 u_int64_t tm_maxfilesize;
392 * The used list contains all nodes that are currently used by
393 * the file system; i.e., they refer to existing files.
395 struct tmpfs_node_list tm_nodes_used;
397 /* All node lock to protect the node list and tmp_pages_used. */
398 struct mtx tm_allnode_lock;
400 /* Read-only status. */
402 /* Do not use namecache. */
404 /* Do not update mtime on writes through mmaped areas. */
407 #define TMPFS_LOCK(tm) mtx_lock(&(tm)->tm_allnode_lock)
408 #define TMPFS_UNLOCK(tm) mtx_unlock(&(tm)->tm_allnode_lock)
409 #define TMPFS_MP_ASSERT_LOCKED(tm) mtx_assert(&(tm)->tm_allnode_lock, MA_OWNED)
412 * This structure maps a file identifier to a tmpfs node. Used by the
415 struct tmpfs_fid_data {
417 unsigned long tfd_gen;
419 _Static_assert(sizeof(struct tmpfs_fid_data) <= MAXFIDSZ,
420 "(struct tmpfs_fid_data) is larger than (struct fid).fid_data");
422 struct tmpfs_dir_cursor {
423 struct tmpfs_dirent *tdc_current;
424 struct tmpfs_dirent *tdc_tree;
429 * Prototypes for tmpfs_subr.c.
432 void tmpfs_ref_node(struct tmpfs_node *node);
433 int tmpfs_alloc_node(struct mount *mp, struct tmpfs_mount *, enum vtype,
434 uid_t uid, gid_t gid, mode_t mode, struct tmpfs_node *,
435 const char *, dev_t, struct tmpfs_node **);
436 int tmpfs_fo_close(struct file *fp, struct thread *td);
437 void tmpfs_free_node(struct tmpfs_mount *, struct tmpfs_node *);
438 bool tmpfs_free_node_locked(struct tmpfs_mount *, struct tmpfs_node *, bool);
439 void tmpfs_free_tmp(struct tmpfs_mount *);
440 int tmpfs_alloc_dirent(struct tmpfs_mount *, struct tmpfs_node *,
441 const char *, u_int, struct tmpfs_dirent **);
442 void tmpfs_free_dirent(struct tmpfs_mount *, struct tmpfs_dirent *);
443 void tmpfs_dirent_init(struct tmpfs_dirent *, const char *, u_int);
444 void tmpfs_destroy_vobject(struct vnode *vp, vm_object_t obj);
445 int tmpfs_alloc_vp(struct mount *, struct tmpfs_node *, int,
447 void tmpfs_free_vp(struct vnode *);
448 int tmpfs_alloc_file(struct vnode *, struct vnode **, struct vattr *,
449 struct componentname *, const char *);
450 void tmpfs_check_mtime(struct vnode *);
451 void tmpfs_dir_attach(struct vnode *, struct tmpfs_dirent *);
452 void tmpfs_dir_detach(struct vnode *, struct tmpfs_dirent *);
453 void tmpfs_dir_destroy(struct tmpfs_mount *, struct tmpfs_node *);
454 struct tmpfs_dirent * tmpfs_dir_lookup(struct tmpfs_node *node,
455 struct tmpfs_node *f,
456 struct componentname *cnp);
457 int tmpfs_dir_getdents(struct tmpfs_mount *, struct tmpfs_node *,
458 struct uio *, int, uint64_t *, int *);
459 int tmpfs_dir_whiteout_add(struct vnode *, struct componentname *);
460 void tmpfs_dir_whiteout_remove(struct vnode *, struct componentname *);
461 int tmpfs_reg_resize(struct vnode *, off_t, boolean_t);
462 int tmpfs_reg_punch_hole(struct vnode *vp, off_t *, off_t *);
463 int tmpfs_chflags(struct vnode *, u_long, struct ucred *, struct thread *);
464 int tmpfs_chmod(struct vnode *, mode_t, struct ucred *, struct thread *);
465 int tmpfs_chown(struct vnode *, uid_t, gid_t, struct ucred *,
467 int tmpfs_chsize(struct vnode *, u_quad_t, struct ucred *, struct thread *);
468 int tmpfs_chtimes(struct vnode *, struct vattr *, struct ucred *cred,
470 void tmpfs_itimes(struct vnode *, const struct timespec *,
471 const struct timespec *);
473 void tmpfs_set_accessed(struct tmpfs_mount *tm, struct tmpfs_node *node);
474 void tmpfs_set_status(struct tmpfs_mount *tm, struct tmpfs_node *node,
476 int tmpfs_truncate(struct vnode *, off_t);
477 struct tmpfs_dirent *tmpfs_dir_first(struct tmpfs_node *dnode,
478 struct tmpfs_dir_cursor *dc);
479 struct tmpfs_dirent *tmpfs_dir_next(struct tmpfs_node *dnode,
480 struct tmpfs_dir_cursor *dc);
482 tmpfs_update(struct vnode *vp)
485 tmpfs_itimes(vp, NULL, NULL);
489 * Convenience macros to simplify some logical expressions.
491 #define IMPLIES(a, b) (!(a) || (b))
492 #define IFF(a, b) (IMPLIES(a, b) && IMPLIES(b, a))
495 * Checks that the directory entry pointed by 'de' matches the name 'name'
496 * with a length of 'len'.
498 #define TMPFS_DIRENT_MATCHES(de, name, len) \
499 (de->td_namelen == len && \
500 bcmp((de)->ud.td_name, (name), (de)->td_namelen) == 0)
503 * Ensures that the node pointed by 'node' is a directory and that its
504 * contents are consistent with respect to directories.
506 #define TMPFS_VALIDATE_DIR(node) do { \
507 MPASS((node)->tn_type == VDIR); \
508 MPASS((node)->tn_size % sizeof(struct tmpfs_dirent) == 0); \
512 * Amount of memory pages to reserve for the system (e.g., to not use by
515 #if !defined(TMPFS_PAGES_MINRESERVED)
516 #define TMPFS_PAGES_MINRESERVED (4 * 1024 * 1024 / PAGE_SIZE)
519 size_t tmpfs_mem_avail(void);
520 size_t tmpfs_pages_used(struct tmpfs_mount *tmp);
521 int tmpfs_subr_init(void);
522 void tmpfs_subr_uninit(void);
524 extern int tmpfs_pager_type;
527 * Macros/functions to convert from generic data structures to tmpfs
531 static inline struct tmpfs_mount *
532 VFS_TO_TMPFS(struct mount *mp)
534 struct tmpfs_mount *tmp;
536 MPASS(mp != NULL && mp->mnt_data != NULL);
537 tmp = (struct tmpfs_mount *)mp->mnt_data;
541 static inline struct tmpfs_node *
542 VP_TO_TMPFS_NODE(struct vnode *vp)
544 struct tmpfs_node *node;
546 MPASS(vp != NULL && vp->v_data != NULL);
547 node = (struct tmpfs_node *)vp->v_data;
551 #define VP_TO_TMPFS_NODE_SMR(vp) \
552 ((struct tmpfs_node *)vn_load_v_data_smr(vp))
554 static inline struct tmpfs_node *
555 VP_TO_TMPFS_DIR(struct vnode *vp)
557 struct tmpfs_node *node;
559 node = VP_TO_TMPFS_NODE(vp);
560 TMPFS_VALIDATE_DIR(node);
565 tmpfs_use_nc(struct vnode *vp)
568 return (!(VFS_TO_TMPFS(vp->v_mount)->tm_nonc));
572 tmpfs_update_getattr(struct vnode *vp)
574 struct tmpfs_node *node;
576 node = VP_TO_TMPFS_NODE(vp);
577 if (__predict_false((node->tn_status & (TMPFS_NODE_MODIFIED |
578 TMPFS_NODE_CHANGED)) != 0 || node->tn_accessed))
582 extern struct fileops tmpfs_fnops;
586 #endif /* _FS_TMPFS_TMPFS_H_ */