xref: /titanic_41/usr/src/uts/common/fs/zfs/sys/dmu.h (revision f808c858fa61e7769218966759510a8b1190dfcf)
1 /*
2  * CDDL HEADER START
3  *
4  * The contents of this file are subject to the terms of the
5  * Common Development and Distribution License (the "License").
6  * You may not use this file except in compliance with the License.
7  *
8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9  * or http://www.opensolaris.org/os/licensing.
10  * See the License for the specific language governing permissions
11  * and limitations under the License.
12  *
13  * When distributing Covered Code, include this CDDL HEADER in each
14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15  * If applicable, add the following below this CDDL HEADER, with the
16  * fields enclosed by brackets "[]" replaced with your own identifying
17  * information: Portions Copyright [yyyy] [name of copyright owner]
18  *
19  * CDDL HEADER END
20  */
21 /*
22  * Copyright 2006 Sun Microsystems, Inc.  All rights reserved.
23  * Use is subject to license terms.
24  */
25 
26 #ifndef	_SYS_DMU_H
27 #define	_SYS_DMU_H
28 
29 #pragma ident	"%Z%%M%	%I%	%E% SMI"
30 
31 /*
32  * This file describes the interface that the DMU provides for its
33  * consumers.
34  *
35  * The DMU also interacts with the SPA.  That interface is described in
36  * dmu_spa.h.
37  */
38 
39 #include <sys/inttypes.h>
40 #include <sys/types.h>
41 #include <sys/param.h>
42 
43 #ifdef	__cplusplus
44 extern "C" {
45 #endif
46 
47 struct uio;
48 struct vnode;
49 struct spa;
50 struct zilog;
51 struct zio;
52 struct blkptr;
53 struct zap_cursor;
54 struct dsl_dataset;
55 struct dsl_pool;
56 struct dnode;
57 struct drr_begin;
58 struct drr_end;
59 struct zbookmark;
60 struct spa;
61 
62 typedef struct objset objset_t;
63 typedef struct dmu_tx dmu_tx_t;
64 typedef struct dsl_dir dsl_dir_t;
65 
66 typedef enum dmu_object_type {
67 	DMU_OT_NONE,
68 	/* general: */
69 	DMU_OT_OBJECT_DIRECTORY,	/* ZAP */
70 	DMU_OT_OBJECT_ARRAY,		/* UINT64 */
71 	DMU_OT_PACKED_NVLIST,		/* UINT8 (XDR by nvlist_pack/unpack) */
72 	DMU_OT_PACKED_NVLIST_SIZE,	/* UINT64 */
73 	DMU_OT_BPLIST,			/* UINT64 */
74 	DMU_OT_BPLIST_HDR,		/* UINT64 */
75 	/* spa: */
76 	DMU_OT_SPACE_MAP_HEADER,	/* UINT64 */
77 	DMU_OT_SPACE_MAP,		/* UINT64 */
78 	/* zil: */
79 	DMU_OT_INTENT_LOG,		/* UINT64 */
80 	/* dmu: */
81 	DMU_OT_DNODE,			/* DNODE */
82 	DMU_OT_OBJSET,			/* OBJSET */
83 	/* dsl: */
84 	DMU_OT_DSL_DIR,			/* UINT64 */
85 	DMU_OT_DSL_DIR_CHILD_MAP,	/* ZAP */
86 	DMU_OT_DSL_DS_SNAP_MAP,		/* ZAP */
87 	DMU_OT_DSL_PROPS,		/* ZAP */
88 	DMU_OT_DSL_DATASET,		/* UINT64 */
89 	/* zpl: */
90 	DMU_OT_ZNODE,			/* ZNODE */
91 	DMU_OT_ACL,			/* ACL */
92 	DMU_OT_PLAIN_FILE_CONTENTS,	/* UINT8 */
93 	DMU_OT_DIRECTORY_CONTENTS,	/* ZAP */
94 	DMU_OT_MASTER_NODE,		/* ZAP */
95 	DMU_OT_DELETE_QUEUE,		/* ZAP */
96 	/* zvol: */
97 	DMU_OT_ZVOL,			/* UINT8 */
98 	DMU_OT_ZVOL_PROP,		/* ZAP */
99 	/* other; for testing only! */
100 	DMU_OT_PLAIN_OTHER,		/* UINT8 */
101 	DMU_OT_UINT64_OTHER,		/* UINT64 */
102 	DMU_OT_ZAP_OTHER,		/* ZAP */
103 	/* new object types: */
104 	DMU_OT_ERROR_LOG,		/* ZAP */
105 
106 	DMU_OT_NUMTYPES
107 } dmu_object_type_t;
108 
109 typedef enum dmu_objset_type {
110 	DMU_OST_NONE,
111 	DMU_OST_META,
112 	DMU_OST_ZFS,
113 	DMU_OST_ZVOL,
114 	DMU_OST_OTHER,			/* For testing only! */
115 	DMU_OST_ANY,			/* Be careful! */
116 	DMU_OST_NUMTYPES
117 } dmu_objset_type_t;
118 
119 void byteswap_uint64_array(void *buf, size_t size);
120 void byteswap_uint32_array(void *buf, size_t size);
121 void byteswap_uint16_array(void *buf, size_t size);
122 void byteswap_uint8_array(void *buf, size_t size);
123 void zap_byteswap(void *buf, size_t size);
124 void zfs_acl_byteswap(void *buf, size_t size);
125 void zfs_znode_byteswap(void *buf, size_t size);
126 
127 #define	DS_MODE_NONE		0	/* invalid, to aid debugging */
128 #define	DS_MODE_STANDARD	1	/* normal access, no special needs */
129 #define	DS_MODE_PRIMARY		2	/* the "main" access, e.g. a mount */
130 #define	DS_MODE_EXCLUSIVE	3	/* exclusive access, e.g. to destroy */
131 #define	DS_MODE_LEVELS		4
132 #define	DS_MODE_LEVEL(x)	((x) & (DS_MODE_LEVELS - 1))
133 #define	DS_MODE_READONLY	0x8
134 #define	DS_MODE_IS_READONLY(x)	((x) & DS_MODE_READONLY)
135 #define	DS_MODE_INCONSISTENT	0x10
136 #define	DS_MODE_IS_INCONSISTENT(x)	((x) & DS_MODE_INCONSISTENT)
137 
138 #define	DS_FIND_SNAPSHOTS	(1<<0)
139 #define	DS_FIND_CHILDREN	(1<<1)
140 
141 /*
142  * The maximum number of bytes that can be accessed as part of one
143  * operation, including metadata.
144  */
145 #define	DMU_MAX_ACCESS (10<<20) /* 10MB */
146 
147 /*
148  * Public routines to create, destroy, open, and close objsets.
149  */
150 int dmu_objset_open(const char *name, dmu_objset_type_t type, int mode,
151     objset_t **osp);
152 void dmu_objset_close(objset_t *os);
153 int dmu_objset_evict_dbufs(objset_t *os, int try);
154 int dmu_objset_create(const char *name, dmu_objset_type_t type,
155     objset_t *clone_parent,
156     void (*func)(objset_t *os, void *arg, dmu_tx_t *tx), void *arg);
157 int dmu_objset_destroy(const char *name);
158 int dmu_snapshots_destroy(char *fsname, char *snapname);
159 int dmu_objset_rollback(const char *name);
160 int dmu_objset_snapshot(char *fsname, char *snapname, boolean_t recursive);
161 int dmu_objset_rename(const char *name, const char *newname);
162 void dmu_objset_set_quota(objset_t *os, uint64_t quota);
163 uint64_t dmu_objset_get_quota(objset_t *os);
164 int dmu_objset_request_reservation(objset_t *os, uint64_t reservation);
165 int dmu_objset_find(char *name, int func(char *, void *), void *arg,
166     int flags);
167 void dmu_objset_byteswap(void *buf, size_t size);
168 
169 typedef struct dmu_buf {
170 	uint64_t db_object;		/* object that this buffer is part of */
171 	uint64_t db_offset;		/* byte offset in this object */
172 	uint64_t db_size;		/* size of buffer in bytes */
173 	void *db_data;			/* data in buffer */
174 } dmu_buf_t;
175 
176 typedef void dmu_buf_evict_func_t(struct dmu_buf *db, void *user_ptr);
177 
178 /*
179  * Callback function to perform byte swapping on a block.
180  */
181 typedef void dmu_byteswap_func_t(void *buf, size_t size);
182 
183 /*
184  * The names of zap entries in the DIRECTORY_OBJECT of the MOS.
185  */
186 #define	DMU_POOL_DIRECTORY_OBJECT	1
187 #define	DMU_POOL_CONFIG			"config"
188 #define	DMU_POOL_ROOT_DATASET		"root_dataset"
189 #define	DMU_POOL_SYNC_BPLIST		"sync_bplist"
190 #define	DMU_POOL_ERRLOG_SCRUB		"errlog_scrub"
191 #define	DMU_POOL_ERRLOG_LAST		"errlog_last"
192 #define	DMU_POOL_SPARES			"spares"
193 #define	DMU_POOL_DEFLATE		"deflate"
194 
195 /*
196  * Allocate an object from this objset.  The range of object numbers
197  * available is (0, DN_MAX_OBJECT).  Object 0 is the meta-dnode.
198  *
199  * The transaction must be assigned to a txg.  The newly allocated
200  * object will be "held" in the transaction (ie. you can modify the
201  * newly allocated object in this transaction).
202  *
203  * dmu_object_alloc() chooses an object and returns it in *objectp.
204  *
205  * dmu_object_claim() allocates a specific object number.  If that
206  * number is already allocated, it fails and returns EEXIST.
207  *
208  * Return 0 on success, or ENOSPC or EEXIST as specified above.
209  */
210 uint64_t dmu_object_alloc(objset_t *os, dmu_object_type_t ot,
211     int blocksize, dmu_object_type_t bonus_type, int bonus_len, dmu_tx_t *tx);
212 int dmu_object_claim(objset_t *os, uint64_t object, dmu_object_type_t ot,
213     int blocksize, dmu_object_type_t bonus_type, int bonus_len, dmu_tx_t *tx);
214 int dmu_object_reclaim(objset_t *os, uint64_t object, dmu_object_type_t ot,
215     int blocksize, dmu_object_type_t bonustype, int bonuslen, dmu_tx_t *tx);
216 
217 /*
218  * Free an object from this objset.
219  *
220  * The object's data will be freed as well (ie. you don't need to call
221  * dmu_free(object, 0, -1, tx)).
222  *
223  * The object need not be held in the transaction.
224  *
225  * If there are any holds on this object's buffers (via dmu_buf_hold()),
226  * or tx holds on the object (via dmu_tx_hold_object()), you can not
227  * free it; it fails and returns EBUSY.
228  *
229  * If the object is not allocated, it fails and returns ENOENT.
230  *
231  * Return 0 on success, or EBUSY or ENOENT as specified above.
232  */
233 int dmu_object_free(objset_t *os, uint64_t object, dmu_tx_t *tx);
234 
235 /*
236  * Find the next allocated or free object.
237  *
238  * The objectp parameter is in-out.  It will be updated to be the next
239  * object which is allocated.
240  *
241  * XXX Can only be called on a objset with no dirty data.
242  *
243  * Returns 0 on success, or ENOENT if there are no more objects.
244  */
245 int dmu_object_next(objset_t *os, uint64_t *objectp, boolean_t hole);
246 
247 /*
248  * Set the data blocksize for an object.
249  *
250  * The object cannot have any blocks allcated beyond the first.  If
251  * the first block is allocated already, the new size must be greater
252  * than the current block size.  If these conditions are not met,
253  * ENOTSUP will be returned.
254  *
255  * Returns 0 on success, or EBUSY if there are any holds on the object
256  * contents, or ENOTSUP as described above.
257  */
258 int dmu_object_set_blocksize(objset_t *os, uint64_t object, uint64_t size,
259     int ibs, dmu_tx_t *tx);
260 
261 /*
262  * Set the checksum property on a dnode.  The new checksum algorithm will
263  * apply to all newly written blocks; existing blocks will not be affected.
264  */
265 void dmu_object_set_checksum(objset_t *os, uint64_t object, uint8_t checksum,
266     dmu_tx_t *tx);
267 
268 /*
269  * Set the compress property on a dnode.  The new compression algorithm will
270  * apply to all newly written blocks; existing blocks will not be affected.
271  */
272 void dmu_object_set_compress(objset_t *os, uint64_t object, uint8_t compress,
273     dmu_tx_t *tx);
274 
275 /*
276  * Decide how many copies of a given block we should make.  Can be from
277  * 1 to SPA_DVAS_PER_BP.
278  */
279 int dmu_get_replication_level(struct spa *spa, struct zbookmark *zb,
280     dmu_object_type_t ot);
281 /*
282  * The bonus data is accessed more or less like a regular buffer.
283  * You must dmu_bonus_hold() to get the buffer, which will give you a
284  * dmu_buf_t with db_offset==-1ULL, and db_size = the size of the bonus
285  * data.  As with any normal buffer, you must call dmu_buf_read() to
286  * read db_data, dmu_buf_will_dirty() before modifying it, and the
287  * object must be held in an assigned transaction before calling
288  * dmu_buf_will_dirty.  You may use dmu_buf_set_user() on the bonus
289  * buffer as well.  You must release your hold with dmu_buf_rele().
290  */
291 int dmu_bonus_hold(objset_t *os, uint64_t object, void *tag, dmu_buf_t **);
292 int dmu_bonus_max(void);
293 
294 /*
295  * Obtain the DMU buffer from the specified object which contains the
296  * specified offset.  dmu_buf_hold() puts a "hold" on the buffer, so
297  * that it will remain in memory.  You must release the hold with
298  * dmu_buf_rele().  You musn't access the dmu_buf_t after releasing your
299  * hold.  You must have a hold on any dmu_buf_t* you pass to the DMU.
300  *
301  * You must call dmu_buf_read, dmu_buf_will_dirty, or dmu_buf_will_fill
302  * on the returned buffer before reading or writing the buffer's
303  * db_data.  The comments for those routines describe what particular
304  * operations are valid after calling them.
305  *
306  * The object number must be a valid, allocated object number.
307  */
308 int dmu_buf_hold(objset_t *os, uint64_t object, uint64_t offset,
309     void *tag, dmu_buf_t **);
310 void dmu_buf_add_ref(dmu_buf_t *db, void* tag);
311 void dmu_buf_rele(dmu_buf_t *db, void *tag);
312 uint64_t dmu_buf_refcount(dmu_buf_t *db);
313 
314 /*
315  * dmu_buf_hold_array holds the DMU buffers which contain all bytes in a
316  * range of an object.  A pointer to an array of dmu_buf_t*'s is
317  * returned (in *dbpp).
318  *
319  * dmu_buf_rele_array releases the hold on an array of dmu_buf_t*'s, and
320  * frees the array.  The hold on the array of buffers MUST be released
321  * with dmu_buf_rele_array.  You can NOT release the hold on each buffer
322  * individually with dmu_buf_rele.
323  */
324 int dmu_buf_hold_array(objset_t *os, uint64_t object, uint64_t offset,
325     uint64_t length, int read, void *tag, int *numbufsp, dmu_buf_t ***dbpp);
326 int dmu_buf_hold_array_by_bonus(dmu_buf_t *db, uint64_t offset,
327     uint64_t length, int read, void *tag, int *numbufsp, dmu_buf_t ***dbpp);
328 void dmu_buf_rele_array(dmu_buf_t **, int numbufs, void *tag);
329 
330 /*
331  * Returns NULL on success, or the existing user ptr if it's already
332  * been set.
333  *
334  * user_ptr is for use by the user and can be obtained via dmu_buf_get_user().
335  *
336  * user_data_ptr_ptr should be NULL, or a pointer to a pointer which
337  * will be set to db->db_data when you are allowed to access it.  Note
338  * that db->db_data (the pointer) can change when you do dmu_buf_read(),
339  * dmu_buf_tryupgrade(), dmu_buf_will_dirty(), or dmu_buf_will_fill().
340  * *user_data_ptr_ptr will be set to the new value when it changes.
341  *
342  * If non-NULL, pageout func will be called when this buffer is being
343  * excised from the cache, so that you can clean up the data structure
344  * pointed to by user_ptr.
345  *
346  * dmu_evict_user() will call the pageout func for all buffers in a
347  * objset with a given pageout func.
348  */
349 void *dmu_buf_set_user(dmu_buf_t *db, void *user_ptr, void *user_data_ptr_ptr,
350     dmu_buf_evict_func_t *pageout_func);
351 /*
352  * set_user_ie is the same as set_user, but request immediate eviction
353  * when hold count goes to zero.
354  */
355 void *dmu_buf_set_user_ie(dmu_buf_t *db, void *user_ptr,
356     void *user_data_ptr_ptr, dmu_buf_evict_func_t *pageout_func);
357 void *dmu_buf_update_user(dmu_buf_t *db_fake, void *old_user_ptr,
358     void *user_ptr, void *user_data_ptr_ptr,
359     dmu_buf_evict_func_t *pageout_func);
360 void dmu_evict_user(objset_t *os, dmu_buf_evict_func_t *func);
361 
362 void dmu_buf_hold_data(dmu_buf_t *db);
363 void dmu_buf_rele_data(dmu_buf_t *db);
364 
365 /*
366  * Returns the user_ptr set with dmu_buf_set_user(), or NULL if not set.
367  */
368 void *dmu_buf_get_user(dmu_buf_t *db);
369 
370 /*
371  * Indicate that you are going to modify the buffer's data (db_data).
372  *
373  * The transaction (tx) must be assigned to a txg (ie. you've called
374  * dmu_tx_assign()).  The buffer's object must be held in the tx
375  * (ie. you've called dmu_tx_hold_object(tx, db->db_object)).
376  */
377 void dmu_buf_will_dirty(dmu_buf_t *db, dmu_tx_t *tx);
378 
379 /*
380  * You must create a transaction, then hold the objects which you will
381  * (or might) modify as part of this transaction.  Then you must assign
382  * the transaction to a transaction group.  Once the transaction has
383  * been assigned, you can modify buffers which belong to held objects as
384  * part of this transaction.  You can't modify buffers before the
385  * transaction has been assigned; you can't modify buffers which don't
386  * belong to objects which this transaction holds; you can't hold
387  * objects once the transaction has been assigned.  You may hold an
388  * object which you are going to free (with dmu_object_free()), but you
389  * don't have to.
390  *
391  * You can abort the transaction before it has been assigned.
392  *
393  * Note that you may hold buffers (with dmu_buf_hold) at any time,
394  * regardless of transaction state.
395  */
396 
397 #define	DMU_NEW_OBJECT	(-1ULL)
398 #define	DMU_OBJECT_END	(-1ULL)
399 
400 dmu_tx_t *dmu_tx_create(objset_t *os);
401 void dmu_tx_hold_write(dmu_tx_t *tx, uint64_t object, uint64_t off, int len);
402 void dmu_tx_hold_free(dmu_tx_t *tx, uint64_t object, uint64_t off,
403     uint64_t len);
404 void dmu_tx_hold_zap(dmu_tx_t *tx, uint64_t object, int add, char *name);
405 void dmu_tx_hold_bonus(dmu_tx_t *tx, uint64_t object);
406 void dmu_tx_abort(dmu_tx_t *tx);
407 int dmu_tx_assign(dmu_tx_t *tx, uint64_t txg_how);
408 void dmu_tx_wait(dmu_tx_t *tx);
409 void dmu_tx_commit(dmu_tx_t *tx);
410 
411 /*
412  * Free up the data blocks for a defined range of a file.  If size is
413  * zero, the range from offset to end-of-file is freed.
414  */
415 int dmu_free_range(objset_t *os, uint64_t object, uint64_t offset,
416 	uint64_t size, dmu_tx_t *tx);
417 
418 /*
419  * Convenience functions.
420  *
421  * Canfail routines will return 0 on success, or an errno if there is a
422  * nonrecoverable I/O error.
423  */
424 int dmu_read(objset_t *os, uint64_t object, uint64_t offset, uint64_t size,
425 	void *buf);
426 void dmu_write(objset_t *os, uint64_t object, uint64_t offset, uint64_t size,
427 	const void *buf, dmu_tx_t *tx);
428 int dmu_write_uio(objset_t *os, uint64_t object, uint64_t offset, uint64_t size,
429     struct uio *uio, dmu_tx_t *tx);
430 
431 /*
432  * Asynchronously try to read in the data.
433  */
434 void dmu_prefetch(objset_t *os, uint64_t object, uint64_t offset,
435     uint64_t len);
436 
437 typedef struct dmu_object_info {
438 	/* All sizes are in bytes. */
439 	uint32_t doi_data_block_size;
440 	uint32_t doi_metadata_block_size;
441 	uint64_t doi_bonus_size;
442 	dmu_object_type_t doi_type;
443 	dmu_object_type_t doi_bonus_type;
444 	uint8_t doi_indirection;		/* 2 = dnode->indirect->data */
445 	uint8_t doi_checksum;
446 	uint8_t doi_compress;
447 	uint8_t doi_pad[5];
448 	/* Values below are number of 512-byte blocks. */
449 	uint64_t doi_physical_blks;		/* data + metadata */
450 	uint64_t doi_max_block_offset;
451 } dmu_object_info_t;
452 
453 typedef struct dmu_object_type_info {
454 	dmu_byteswap_func_t	*ot_byteswap;
455 	boolean_t		ot_metadata;
456 	char			*ot_name;
457 } dmu_object_type_info_t;
458 
459 extern const dmu_object_type_info_t dmu_ot[DMU_OT_NUMTYPES];
460 
461 /*
462  * Get information on a DMU object.
463  *
464  * Return 0 on success or ENOENT if object is not allocated.
465  *
466  * If doi is NULL, just indicates whether the object exists.
467  */
468 int dmu_object_info(objset_t *os, uint64_t object, dmu_object_info_t *doi);
469 void dmu_object_info_from_dnode(struct dnode *dn, dmu_object_info_t *doi);
470 void dmu_object_info_from_db(dmu_buf_t *db, dmu_object_info_t *doi);
471 void dmu_object_size_from_db(dmu_buf_t *db, uint32_t *blksize,
472     u_longlong_t *nblk512);
473 
474 /*
475  * Get the maximum nonzero offset in the object (ie. this offset and all
476  * offsets following are zero).
477  *
478  * XXX Perhaps integrate this with dmu_object_info(), although that
479  * would then have to bring in the indirect blocks.
480  */
481 uint64_t dmu_object_max_nonzero_offset(objset_t *os, uint64_t object);
482 
483 typedef struct dmu_objset_stats {
484 	dmu_objset_type_t dds_type;
485 	uint8_t dds_is_snapshot;
486 	uint8_t dds_inconsistent;
487 	uint8_t dds_pad[2];
488 
489 	uint64_t dds_creation_time;
490 	uint64_t dds_creation_txg;
491 
492 	char dds_clone_of[MAXNAMELEN];
493 
494 	/* How much data is there in this objset? */
495 
496 	/*
497 	 * Space referenced, taking into account pending writes and
498 	 * frees.  Only relavent to filesystems and snapshots (not
499 	 * collections).
500 	 */
501 	uint64_t dds_space_refd;
502 
503 	/*
504 	 * Space "used", taking into account pending writes and frees, and
505 	 * children's reservations (in bytes).  This is the amount of
506 	 * space that will be freed if this and all dependent items are
507 	 * destroyed (eg. child datasets, objsets, and snapshots).  So
508 	 * for snapshots, this is the amount of space unique to this
509 	 * snapshot.
510 	 */
511 	uint64_t dds_space_used;
512 
513 	/*
514 	 * Compressed and uncompressed bytes consumed.  Does not take
515 	 * into account reservations.  Used for computing compression
516 	 * ratio.
517 	 */
518 	uint64_t dds_compressed_bytes;
519 	uint64_t dds_uncompressed_bytes;
520 
521 	/*
522 	 * The ds_fsid_guid is a 56-bit ID that can change to avoid
523 	 * collisions.  The ds_guid is a 64-bit ID that will never
524 	 * change, so there is a small probability that it will collide.
525 	 */
526 	uint64_t dds_fsid_guid;
527 
528 	uint64_t dds_objects_used;	/* number of objects used */
529 	uint64_t dds_objects_avail;	/* number of objects available */
530 
531 	uint64_t dds_num_clones; /* number of clones of this */
532 
533 	/* The dataset's administratively-set quota, in bytes. */
534 	uint64_t dds_quota;
535 
536 	/* The dataset's administratively-set reservation, in bytes */
537 	uint64_t dds_reserved;
538 
539 	/*
540 	 * The amount of additional space that this dataset can consume.
541 	 * Takes into account quotas & reservations.
542 	 * (Assuming that no other datasets consume it first.)
543 	 */
544 	uint64_t dds_available;
545 
546 	/*
547 	 * Used for debugging purposes
548 	 */
549 	uint64_t dds_last_txg;
550 } dmu_objset_stats_t;
551 
552 /*
553  * Get stats on a dataset.
554  */
555 void dmu_objset_stats(objset_t *os, dmu_objset_stats_t *dds);
556 
557 int dmu_objset_is_snapshot(objset_t *os);
558 
559 extern struct spa *dmu_objset_spa(objset_t *os);
560 extern struct zilog *dmu_objset_zil(objset_t *os);
561 extern struct dsl_pool *dmu_objset_pool(objset_t *os);
562 extern struct dsl_dataset *dmu_objset_ds(objset_t *os);
563 extern void dmu_objset_name(objset_t *os, char *buf);
564 extern dmu_objset_type_t dmu_objset_type(objset_t *os);
565 extern uint64_t dmu_objset_id(objset_t *os);
566 extern int dmu_snapshot_list_next(objset_t *os, int namelen, char *name,
567     uint64_t *id, uint64_t *offp);
568 extern int dmu_dir_list_next(objset_t *os, int namelen, char *name,
569     uint64_t *idp, uint64_t *offp);
570 
571 /*
572  * Return the txg number for the given assigned transaction.
573  */
574 uint64_t dmu_tx_get_txg(dmu_tx_t *tx);
575 
576 /*
577  * Synchronous write.
578  * If a parent zio is provided this function initiates a write on the
579  * provided buffer as a child of the parent zio.
580  * In the absense of a parent zio, the write is completed synchronously.
581  * At write completion, blk is filled with the bp of the written block.
582  * Note that while the data covered by this function will be on stable
583  * storage when the write completes this new data does not become a
584  * permanent part of the file until the associated transaction commits.
585  */
586 typedef void dmu_sync_cb_t(dmu_buf_t *db, void *arg);
587 int dmu_sync(struct zio *zio, dmu_buf_t *db,
588     struct blkptr *bp, uint64_t txg, dmu_sync_cb_t *done, void *arg);
589 
590 /*
591  * Find the next hole or data block in file starting at *off
592  * Return found offset in *off. Return ESRCH for end of file.
593  */
594 int dmu_offset_next(objset_t *os, uint64_t object, boolean_t hole,
595     uint64_t *off);
596 
597 /*
598  * Initial setup and final teardown.
599  */
600 extern void dmu_init(void);
601 extern void dmu_fini(void);
602 
603 typedef void (*dmu_traverse_cb_t)(objset_t *os, void *arg, struct blkptr *bp,
604     uint64_t object, uint64_t offset, int len);
605 void dmu_traverse_objset(objset_t *os, uint64_t txg_start,
606     dmu_traverse_cb_t cb, void *arg);
607 
608 int dmu_sendbackup(objset_t *tosnap, objset_t *fromsnap, struct vnode *vp);
609 int dmu_recvbackup(char *tosnap, struct drr_begin *drrb, uint64_t *sizep,
610     struct vnode *vp, uint64_t voffset);
611 
612 /* CRC64 table */
613 #define	ZFS_CRC64_POLY	0xC96C5795D7870F42ULL	/* ECMA-182, reflected form */
614 extern uint64_t zfs_crc64_table[256];
615 
616 #ifdef	__cplusplus
617 }
618 #endif
619 
620 #endif	/* _SYS_DMU_H */
621