xref: /freebsd/sys/fs/tmpfs/tmpfs.h (revision 271c3a9060f2ee55607ebe146523f888e1db2654)
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  * 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  * $FreeBSD$
40  */
41 
42 #ifndef _FS_TMPFS_TMPFS_H_
43 #define _FS_TMPFS_TMPFS_H_
44 
45 /* ---------------------------------------------------------------------
46  * KERNEL-SPECIFIC DEFINITIONS
47  * --------------------------------------------------------------------- */
48 #include <sys/dirent.h>
49 #include <sys/mount.h>
50 #include <sys/queue.h>
51 #include <sys/vnode.h>
52 #include <sys/file.h>
53 #include <sys/lock.h>
54 #include <sys/mutex.h>
55 
56 /* --------------------------------------------------------------------- */
57 #include <sys/malloc.h>
58 #include <sys/systm.h>
59 #include <sys/vmmeter.h>
60 #include <vm/swap_pager.h>
61 
62 MALLOC_DECLARE(M_TMPFSMNT);
63 MALLOC_DECLARE(M_TMPFSNAME);
64 
65 /* --------------------------------------------------------------------- */
66 
67 /*
68  * Internal representation of a tmpfs directory entry.
69  */
70 struct tmpfs_dirent {
71 	TAILQ_ENTRY(tmpfs_dirent)	td_entries;
72 
73 	/* Length of the name stored in this directory entry.  This avoids
74 	 * the need to recalculate it every time the name is used. */
75 	uint16_t			td_namelen;
76 
77 	/* The name of the entry, allocated from a string pool.  This
78 	* string is not required to be zero-terminated; therefore, the
79 	* td_namelen field must always be used when accessing its value. */
80 	char *				td_name;
81 
82 	/* Pointer to the node this entry refers to. */
83 	struct tmpfs_node *		td_node;
84 };
85 
86 /* A directory in tmpfs holds a sorted list of directory entries, which in
87  * turn point to other files (which can be directories themselves).
88  *
89  * In tmpfs, this list is managed by a tail queue, whose head is defined by
90  * the struct tmpfs_dir type.
91  *
92  * It is imporant to notice that directories do not have entries for . and
93  * .. as other file systems do.  These can be generated when requested
94  * based on information available by other means, such as the pointer to
95  * the node itself in the former case or the pointer to the parent directory
96  * in the latter case.  This is done to simplify tmpfs's code and, more
97  * importantly, to remove redundancy. */
98 TAILQ_HEAD(tmpfs_dir, tmpfs_dirent);
99 
100 /* Each entry in a directory has a cookie that identifies it.  Cookies
101  * supersede offsets within directories because, given how tmpfs stores
102  * directories in memory, there is no such thing as an offset.  (Emulating
103  * a real offset could be very difficult.)
104  *
105  * The '.', '..' and the end of directory markers have fixed cookies which
106  * cannot collide with the cookies generated by other entries.  The cookies
107  * fot the other entries are generated based on the memory address on which
108  * stores their information is stored.
109  *
110  * Ideally, using the entry's memory pointer as the cookie would be enough
111  * to represent it and it wouldn't cause collisions in any system.
112  * Unfortunately, this results in "offsets" with very large values which
113  * later raise problems in the Linux compatibility layer (and maybe in other
114  * places) as described in PR kern/32034.  Hence we need to workaround this
115  * with a rather ugly hack.
116  *
117  * Linux 32-bit binaries, unless built with _FILE_OFFSET_BITS=64, have off_t
118  * set to 'long', which is a 32-bit *signed* long integer.  Regardless of
119  * the macro value, GLIBC (2.3 at least) always uses the getdents64
120  * system call (when calling readdir) which internally returns off64_t
121  * offsets.  In order to make 32-bit binaries work, *GLIBC* converts the
122  * 64-bit values returned by the kernel to 32-bit ones and aborts with
123  * EOVERFLOW if the conversion results in values that won't fit in 32-bit
124  * integers (which it assumes is because the directory is extremely large).
125  * This wouldn't cause problems if we were dealing with unsigned integers,
126  * but as we have signed integers, this check fails due to sign expansion.
127  *
128  * For example, consider that the kernel returns the 0xc1234567 cookie to
129  * userspace in a off64_t integer.  Later on, GLIBC casts this value to
130  * off_t (remember, signed) with code similar to:
131  *     system call returns the offset in kernel_value;
132  *     off_t casted_value = kernel_value;
133  *     if (sizeof(off_t) != sizeof(off64_t) &&
134  *         kernel_value != casted_value)
135  *             error!
136  * In this case, casted_value still has 0xc1234567, but when it is compared
137  * for equality against kernel_value, it is promoted to a 64-bit integer and
138  * becomes 0xffffffffc1234567, which is different than 0x00000000c1234567.
139  * Then, GLIBC assumes this is because the directory is very large.
140  *
141  * Given that all the above happens in user-space, we have no control over
142  * it; therefore we must workaround the issue here.  We do this by
143  * truncating the pointer value to a 32-bit integer and hope that there
144  * won't be collisions.  In fact, this will not cause any problems in
145  * 32-bit platforms but some might arise in 64-bit machines (I'm not sure
146  * if they can happen at all in practice).
147  *
148  * XXX A nicer solution shall be attempted. */
149 #ifdef _KERNEL
150 #define	TMPFS_DIRCOOKIE_DOT	0
151 #define	TMPFS_DIRCOOKIE_DOTDOT	1
152 #define	TMPFS_DIRCOOKIE_EOF	2
153 static __inline
154 off_t
155 tmpfs_dircookie(struct tmpfs_dirent *de)
156 {
157 	off_t cookie;
158 
159 	cookie = ((off_t)(uintptr_t)de >> 1) & 0x7FFFFFFF;
160 	MPASS(cookie != TMPFS_DIRCOOKIE_DOT);
161 	MPASS(cookie != TMPFS_DIRCOOKIE_DOTDOT);
162 	MPASS(cookie != TMPFS_DIRCOOKIE_EOF);
163 
164 	return cookie;
165 }
166 #endif
167 
168 /* --------------------------------------------------------------------- */
169 
170 /*
171  * Internal representation of a tmpfs file system node.
172  *
173  * This structure is splitted in two parts: one holds attributes common
174  * to all file types and the other holds data that is only applicable to
175  * a particular type.  The code must be careful to only access those
176  * attributes that are actually allowed by the node's type.
177  *
178  *
179  * Below is the key of locks used to protected the fields in the following
180  * structures.
181  *
182  */
183 struct tmpfs_node {
184 	/* Doubly-linked list entry which links all existing nodes for a
185 	 * single file system.  This is provided to ease the removal of
186 	 * all nodes during the unmount operation. */
187 	LIST_ENTRY(tmpfs_node)	tn_entries;
188 
189 	/* The node's type.  Any of 'VBLK', 'VCHR', 'VDIR', 'VFIFO',
190 	 * 'VLNK', 'VREG' and 'VSOCK' is allowed.  The usage of vnode
191 	 * types instead of a custom enumeration is to make things simpler
192 	 * and faster, as we do not need to convert between two types. */
193 	enum vtype		tn_type;
194 
195 	/* Node identifier. */
196 	ino_t			tn_id;
197 
198 	/* Node's internal status.  This is used by several file system
199 	 * operations to do modifications to the node in a delayed
200 	 * fashion. */
201 	int			tn_status;
202 #define	TMPFS_NODE_ACCESSED	(1 << 1)
203 #define	TMPFS_NODE_MODIFIED	(1 << 2)
204 #define	TMPFS_NODE_CHANGED	(1 << 3)
205 
206 	/* The node size.  It does not necessarily match the real amount
207 	 * of memory consumed by it. */
208 	off_t			tn_size;
209 
210 	/* Generic node attributes. */
211 	uid_t			tn_uid;
212 	gid_t			tn_gid;
213 	mode_t			tn_mode;
214 	int			tn_flags;
215 	nlink_t			tn_links;
216 	struct timespec		tn_atime;
217 	struct timespec		tn_mtime;
218 	struct timespec		tn_ctime;
219 	struct timespec		tn_birthtime;
220 	unsigned long		tn_gen;
221 
222 	/* As there is a single vnode for each active file within the
223 	 * system, care has to be taken to avoid allocating more than one
224 	 * vnode per file.  In order to do this, a bidirectional association
225 	 * is kept between vnodes and nodes.
226 	 *
227 	 * Whenever a vnode is allocated, its v_data field is updated to
228 	 * point to the node it references.  At the same time, the node's
229 	 * tn_vnode field is modified to point to the new vnode representing
230 	 * it.  Further attempts to allocate a vnode for this same node will
231 	 * result in returning a new reference to the value stored in
232 	 * tn_vnode.
233 	 *
234 	 * May be NULL when the node is unused (that is, no vnode has been
235 	 * allocated for it or it has been reclaimed). */
236 	struct vnode *		tn_vnode;
237 
238 	/* interlock to protect tn_vpstate */
239 	struct mtx	tn_interlock;
240 
241 	/* Identify if current node has vnode assiocate with
242 	 * or allocating vnode.
243 	 */
244 	int		tn_vpstate;
245 
246 	/* misc data field for different tn_type node */
247 	union {
248 		/* Valid when tn_type == VBLK || tn_type == VCHR. */
249 		dev_t			tn_rdev;
250 
251 		/* Valid when tn_type == VDIR. */
252 		struct tn_dir{
253 			/* Pointer to the parent directory.  The root
254 			 * directory has a pointer to itself in this field;
255 			 * this property identifies the root node. */
256 			struct tmpfs_node *	tn_parent;
257 
258 			/* Head of a tail-queue that links the contents of
259 			 * the directory together.  See above for a
260 			 * description of its contents. */
261 			struct tmpfs_dir	tn_dirhead;
262 
263 			/* Number and pointer of the first directory entry
264 			 * returned by the readdir operation if it were
265 			 * called again to continue reading data from the
266 			 * same directory as before.  This is used to speed
267 			 * up reads of long directories, assuming that no
268 			 * more than one read is in progress at a given time.
269 			 * Otherwise, these values are discarded and a linear
270 			 * scan is performed from the beginning up to the
271 			 * point where readdir starts returning values. */
272 			off_t			tn_readdir_lastn;
273 			struct tmpfs_dirent *	tn_readdir_lastp;
274 		}tn_dir;
275 
276 		/* Valid when tn_type == VLNK. */
277 		/* The link's target, allocated from a string pool. */
278 		char *			tn_link;
279 
280 		/* Valid when tn_type == VREG. */
281 		struct tn_reg {
282 			/* The contents of regular files stored in a tmpfs
283 			 * file system are represented by a single anonymous
284 			 * memory object (aobj, for short).  The aobj provides
285 			 * direct access to any position within the file,
286 			 * because its contents are always mapped in a
287 			 * contiguous region of virtual memory.  It is a task
288 			 * of the memory management subsystem (see uvm(9)) to
289 			 * issue the required page ins or page outs whenever
290 			 * a position within the file is accessed. */
291 			vm_object_t		tn_aobj;
292 			size_t			tn_aobj_pages;
293 
294 		}tn_reg;
295 
296 		/* Valid when tn_type = VFIFO */
297 		struct tn_fifo {
298 			fo_rdwr_t		*tn_fo_read;
299 			fo_rdwr_t		*tn_fo_write;
300 		}tn_fifo;
301 	}tn_spec;
302 };
303 LIST_HEAD(tmpfs_node_list, tmpfs_node);
304 
305 #define tn_rdev tn_spec.tn_rdev
306 #define tn_dir tn_spec.tn_dir
307 #define tn_link tn_spec.tn_link
308 #define tn_reg tn_spec.tn_reg
309 #define tn_fifo tn_spec.tn_fifo
310 
311 #define TMPFS_NODE_LOCK(node) mtx_lock(&(node)->tn_interlock)
312 #define TMPFS_NODE_UNLOCK(node) mtx_unlock(&(node)->tn_interlock)
313 #define        TMPFS_NODE_MTX(node) (&(node)->tn_interlock)
314 
315 #define TMPFS_VNODE_ALLOCATING	1
316 #define TMPFS_VNODE_WANT	2
317 /* --------------------------------------------------------------------- */
318 
319 /*
320  * Internal representation of a tmpfs mount point.
321  */
322 struct tmpfs_mount {
323 	/* Maximum number of memory pages available for use by the file
324 	 * system, set during mount time.  This variable must never be
325 	 * used directly as it may be bigger than the current amount of
326 	 * free memory; in the extreme case, it will hold the SIZE_MAX
327 	 * value.  Instead, use the TMPFS_PAGES_MAX macro. */
328 	size_t			tm_pages_max;
329 
330 	/* Number of pages in use by the file system.  Cannot be bigger
331 	 * than the value returned by TMPFS_PAGES_MAX in any case. */
332 	size_t			tm_pages_used;
333 
334 	/* Pointer to the node representing the root directory of this
335 	 * file system. */
336 	struct tmpfs_node *	tm_root;
337 
338 	/* Maximum number of possible nodes for this file system; set
339 	 * during mount time.  We need a hard limit on the maximum number
340 	 * of nodes to avoid allocating too much of them; their objects
341 	 * cannot be released until the file system is unmounted.
342 	 * Otherwise, we could easily run out of memory by creating lots
343 	 * of empty files and then simply removing them. */
344 	ino_t			tm_nodes_max;
345 
346 	/* unrhdr used to allocate inode numbers */
347 	struct unrhdr *		tm_ino_unr;
348 
349 	/* Number of nodes currently that are in use. */
350 	ino_t			tm_nodes_inuse;
351 
352 	/* maximum representable file size */
353 	u_int64_t		tm_maxfilesize;
354 
355 	/* Nodes are organized in two different lists.  The used list
356 	 * contains all nodes that are currently used by the file system;
357 	 * i.e., they refer to existing files.  The available list contains
358 	 * all nodes that are currently available for use by new files.
359 	 * Nodes must be kept in this list (instead of deleting them)
360 	 * because we need to keep track of their generation number (tn_gen
361 	 * field).
362 	 *
363 	 * Note that nodes are lazily allocated: if the available list is
364 	 * empty and we have enough space to create more nodes, they will be
365 	 * created and inserted in the used list.  Once these are released,
366 	 * they will go into the available list, remaining alive until the
367 	 * file system is unmounted. */
368 	struct tmpfs_node_list	tm_nodes_used;
369 
370 	/* All node lock to protect the node list and tmp_pages_used */
371 	struct mtx allnode_lock;
372 
373 	/* Pools used to store file system meta data.  These are not shared
374 	 * across several instances of tmpfs for the reasons described in
375 	 * tmpfs_pool.c. */
376 	uma_zone_t		tm_dirent_pool;
377 	uma_zone_t		tm_node_pool;
378 };
379 #define TMPFS_LOCK(tm) mtx_lock(&(tm)->allnode_lock)
380 #define TMPFS_UNLOCK(tm) mtx_unlock(&(tm)->allnode_lock)
381 
382 /* --------------------------------------------------------------------- */
383 
384 /*
385  * This structure maps a file identifier to a tmpfs node.  Used by the
386  * NFS code.
387  */
388 struct tmpfs_fid {
389 	uint16_t		tf_len;
390 	uint16_t		tf_pad;
391 	ino_t			tf_id;
392 	unsigned long		tf_gen;
393 };
394 
395 /* --------------------------------------------------------------------- */
396 
397 #ifdef _KERNEL
398 /*
399  * Prototypes for tmpfs_subr.c.
400  */
401 
402 int	tmpfs_alloc_node(struct tmpfs_mount *, enum vtype,
403 	    uid_t uid, gid_t gid, mode_t mode, struct tmpfs_node *,
404 	    char *, dev_t, struct thread *, struct tmpfs_node **);
405 void	tmpfs_free_node(struct tmpfs_mount *, struct tmpfs_node *);
406 int	tmpfs_alloc_dirent(struct tmpfs_mount *, struct tmpfs_node *,
407 	    const char *, uint16_t, struct tmpfs_dirent **);
408 void	tmpfs_free_dirent(struct tmpfs_mount *, struct tmpfs_dirent *,
409 	    boolean_t);
410 int	tmpfs_alloc_vp(struct mount *, struct tmpfs_node *, int,
411 	    struct vnode **, struct thread *);
412 void	tmpfs_free_vp(struct vnode *);
413 int	tmpfs_alloc_file(struct vnode *, struct vnode **, struct vattr *,
414 	    struct componentname *, char *);
415 void	tmpfs_dir_attach(struct vnode *, struct tmpfs_dirent *);
416 void	tmpfs_dir_detach(struct vnode *, struct tmpfs_dirent *);
417 struct tmpfs_dirent *	tmpfs_dir_lookup(struct tmpfs_node *node,
418 			    struct componentname *cnp);
419 struct tmpfs_dirent *tmpfs_dir_search(struct tmpfs_node *node,
420     struct tmpfs_node *f);
421 int	tmpfs_dir_getdotdent(struct tmpfs_node *, struct uio *);
422 int	tmpfs_dir_getdotdotdent(struct tmpfs_node *, struct uio *);
423 struct tmpfs_dirent *	tmpfs_dir_lookupbycookie(struct tmpfs_node *, off_t);
424 int	tmpfs_dir_getdents(struct tmpfs_node *, struct uio *, off_t *);
425 int	tmpfs_reg_resize(struct vnode *, off_t);
426 int	tmpfs_chflags(struct vnode *, int, struct ucred *, struct thread *);
427 int	tmpfs_chmod(struct vnode *, mode_t, struct ucred *, struct thread *);
428 int	tmpfs_chown(struct vnode *, uid_t, gid_t, struct ucred *,
429 	    struct thread *);
430 int	tmpfs_chsize(struct vnode *, u_quad_t, struct ucred *, struct thread *);
431 int	tmpfs_chtimes(struct vnode *, struct timespec *, struct timespec *,
432 	    struct timespec *, int, struct ucred *, struct thread *);
433 void	tmpfs_itimes(struct vnode *, const struct timespec *,
434 	    const struct timespec *);
435 
436 void	tmpfs_update(struct vnode *);
437 int	tmpfs_truncate(struct vnode *, off_t);
438 
439 /* --------------------------------------------------------------------- */
440 
441 /*
442  * Convenience macros to simplify some logical expressions.
443  */
444 #define IMPLIES(a, b) (!(a) || (b))
445 #define IFF(a, b) (IMPLIES(a, b) && IMPLIES(b, a))
446 
447 /* --------------------------------------------------------------------- */
448 
449 /*
450  * Checks that the directory entry pointed by 'de' matches the name 'name'
451  * with a length of 'len'.
452  */
453 #define TMPFS_DIRENT_MATCHES(de, name, len) \
454     (de->td_namelen == (uint16_t)len && \
455     memcmp((de)->td_name, (name), (de)->td_namelen) == 0)
456 
457 /* --------------------------------------------------------------------- */
458 
459 /*
460  * Ensures that the node pointed by 'node' is a directory and that its
461  * contents are consistent with respect to directories.
462  */
463 #define TMPFS_VALIDATE_DIR(node) \
464     MPASS((node)->tn_type == VDIR); \
465     MPASS((node)->tn_size % sizeof(struct tmpfs_dirent) == 0); \
466     MPASS((node)->tn_dir.tn_readdir_lastp == NULL || \
467 	tmpfs_dircookie((node)->tn_dir.tn_readdir_lastp) == (node)->tn_dir.tn_readdir_lastn);
468 
469 /* --------------------------------------------------------------------- */
470 
471 /*
472  * Memory management stuff.
473  */
474 
475 /* Amount of memory pages to reserve for the system (e.g., to not use by
476  * tmpfs).
477  * XXX: Should this be tunable through sysctl, for instance? */
478 #define TMPFS_PAGES_RESERVED (4 * 1024 * 1024 / PAGE_SIZE)
479 
480 /*
481  * Returns information about the number of available memory pages,
482  * including physical and virtual ones.
483  *
484  * If 'total' is TRUE, the value returned is the total amount of memory
485  * pages configured for the system (either in use or free).
486  * If it is FALSE, the value returned is the amount of free memory pages.
487  *
488  * Remember to remove TMPFS_PAGES_RESERVED from the returned value to avoid
489  * excessive memory usage.
490  *
491  */
492 static __inline size_t
493 tmpfs_mem_info(void)
494 {
495 	size_t size;
496 
497 	size = swap_pager_avail + cnt.v_free_count + cnt.v_inactive_count;
498 	size -= size > cnt.v_wire_count ? cnt.v_wire_count : size;
499 	return size;
500 }
501 
502 /* Returns the maximum size allowed for a tmpfs file system.  This macro
503  * must be used instead of directly retrieving the value from tm_pages_max.
504  * The reason is that the size of a tmpfs file system is dynamic: it lets
505  * the user store files as long as there is enough free memory (including
506  * physical memory and swap space).  Therefore, the amount of memory to be
507  * used is either the limit imposed by the user during mount time or the
508  * amount of available memory, whichever is lower.  To avoid consuming all
509  * the memory for a given mount point, the system will always reserve a
510  * minimum of TMPFS_PAGES_RESERVED pages, which is also taken into account
511  * by this macro (see above). */
512 static __inline size_t
513 TMPFS_PAGES_MAX(struct tmpfs_mount *tmp)
514 {
515 	size_t freepages;
516 
517 	freepages = tmpfs_mem_info();
518 	freepages -= freepages < TMPFS_PAGES_RESERVED ?
519 	    freepages : TMPFS_PAGES_RESERVED;
520 
521 	return MIN(tmp->tm_pages_max, freepages + tmp->tm_pages_used);
522 }
523 
524 /* Returns the available space for the given file system. */
525 #define TMPFS_META_PAGES(tmp) (howmany((tmp)->tm_nodes_inuse * (sizeof(struct tmpfs_node) \
526 				+ sizeof(struct tmpfs_dirent)), PAGE_SIZE))
527 #define TMPFS_FILE_PAGES(tmp) ((tmp)->tm_pages_used)
528 
529 #define TMPFS_PAGES_AVAIL(tmp) (TMPFS_PAGES_MAX(tmp) > \
530 			TMPFS_META_PAGES(tmp)+TMPFS_FILE_PAGES(tmp)? \
531 			TMPFS_PAGES_MAX(tmp) - TMPFS_META_PAGES(tmp) \
532 			- TMPFS_FILE_PAGES(tmp):0)
533 
534 #endif
535 
536 /* --------------------------------------------------------------------- */
537 
538 /*
539  * Macros/functions to convert from generic data structures to tmpfs
540  * specific ones.
541  */
542 
543 static inline
544 struct tmpfs_mount *
545 VFS_TO_TMPFS(struct mount *mp)
546 {
547 	struct tmpfs_mount *tmp;
548 
549 	MPASS((mp) != NULL && (mp)->mnt_data != NULL);
550 	tmp = (struct tmpfs_mount *)(mp)->mnt_data;
551 	return tmp;
552 }
553 
554 static inline
555 struct tmpfs_node *
556 VP_TO_TMPFS_NODE(struct vnode *vp)
557 {
558 	struct tmpfs_node *node;
559 
560 	MPASS((vp) != NULL && (vp)->v_data != NULL);
561 	node = (struct tmpfs_node *)vp->v_data;
562 	return node;
563 }
564 
565 static inline
566 struct tmpfs_node *
567 VP_TO_TMPFS_DIR(struct vnode *vp)
568 {
569 	struct tmpfs_node *node;
570 
571 	node = VP_TO_TMPFS_NODE(vp);
572 	TMPFS_VALIDATE_DIR(node);
573 	return node;
574 }
575 
576 #endif /* _FS_TMPFS_TMPFS_H_ */
577