xref: /titanic_44/usr/src/uts/common/fs/zfs/sys/dmu.h (revision a237e38e9161f0acd6451439d4a7dd597e66291d)
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 2007 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 page;
49 struct vnode;
50 struct spa;
51 struct zilog;
52 struct zio;
53 struct blkptr;
54 struct zap_cursor;
55 struct dsl_dataset;
56 struct dsl_pool;
57 struct dnode;
58 struct drr_begin;
59 struct drr_end;
60 struct zbookmark;
61 struct spa;
62 struct nvlist;
63 struct objset_impl;
64 
65 typedef struct objset objset_t;
66 typedef struct dmu_tx dmu_tx_t;
67 typedef struct dsl_dir dsl_dir_t;
68 
69 typedef enum dmu_object_type {
70 	DMU_OT_NONE,
71 	/* general: */
72 	DMU_OT_OBJECT_DIRECTORY,	/* ZAP */
73 	DMU_OT_OBJECT_ARRAY,		/* UINT64 */
74 	DMU_OT_PACKED_NVLIST,		/* UINT8 (XDR by nvlist_pack/unpack) */
75 	DMU_OT_PACKED_NVLIST_SIZE,	/* UINT64 */
76 	DMU_OT_BPLIST,			/* UINT64 */
77 	DMU_OT_BPLIST_HDR,		/* UINT64 */
78 	/* spa: */
79 	DMU_OT_SPACE_MAP_HEADER,	/* UINT64 */
80 	DMU_OT_SPACE_MAP,		/* UINT64 */
81 	/* zil: */
82 	DMU_OT_INTENT_LOG,		/* UINT64 */
83 	/* dmu: */
84 	DMU_OT_DNODE,			/* DNODE */
85 	DMU_OT_OBJSET,			/* OBJSET */
86 	/* dsl: */
87 	DMU_OT_DSL_DIR,			/* UINT64 */
88 	DMU_OT_DSL_DIR_CHILD_MAP,	/* ZAP */
89 	DMU_OT_DSL_DS_SNAP_MAP,		/* ZAP */
90 	DMU_OT_DSL_PROPS,		/* ZAP */
91 	DMU_OT_DSL_DATASET,		/* UINT64 */
92 	/* zpl: */
93 	DMU_OT_ZNODE,			/* ZNODE */
94 	DMU_OT_ACL,			/* ACL */
95 	DMU_OT_PLAIN_FILE_CONTENTS,	/* UINT8 */
96 	DMU_OT_DIRECTORY_CONTENTS,	/* ZAP */
97 	DMU_OT_MASTER_NODE,		/* ZAP */
98 	DMU_OT_UNLINKED_SET,		/* ZAP */
99 	/* zvol: */
100 	DMU_OT_ZVOL,			/* UINT8 */
101 	DMU_OT_ZVOL_PROP,		/* ZAP */
102 	/* other; for testing only! */
103 	DMU_OT_PLAIN_OTHER,		/* UINT8 */
104 	DMU_OT_UINT64_OTHER,		/* UINT64 */
105 	DMU_OT_ZAP_OTHER,		/* ZAP */
106 	/* new object types: */
107 	DMU_OT_ERROR_LOG,		/* ZAP */
108 	DMU_OT_SPA_HISTORY,		/* UINT8 */
109 	DMU_OT_SPA_HISTORY_OFFSETS,	/* spa_his_phys_t */
110 	DMU_OT_POOL_PROPS,		/* ZAP */
111 
112 	DMU_OT_NUMTYPES
113 } dmu_object_type_t;
114 
115 typedef enum dmu_objset_type {
116 	DMU_OST_NONE,
117 	DMU_OST_META,
118 	DMU_OST_ZFS,
119 	DMU_OST_ZVOL,
120 	DMU_OST_OTHER,			/* For testing only! */
121 	DMU_OST_ANY,			/* Be careful! */
122 	DMU_OST_NUMTYPES
123 } dmu_objset_type_t;
124 
125 void byteswap_uint64_array(void *buf, size_t size);
126 void byteswap_uint32_array(void *buf, size_t size);
127 void byteswap_uint16_array(void *buf, size_t size);
128 void byteswap_uint8_array(void *buf, size_t size);
129 void zap_byteswap(void *buf, size_t size);
130 void zfs_acl_byteswap(void *buf, size_t size);
131 void zfs_znode_byteswap(void *buf, size_t size);
132 
133 #define	DS_MODE_NONE		0	/* invalid, to aid debugging */
134 #define	DS_MODE_STANDARD	1	/* normal access, no special needs */
135 #define	DS_MODE_PRIMARY		2	/* the "main" access, e.g. a mount */
136 #define	DS_MODE_EXCLUSIVE	3	/* exclusive access, e.g. to destroy */
137 #define	DS_MODE_LEVELS		4
138 #define	DS_MODE_LEVEL(x)	((x) & (DS_MODE_LEVELS - 1))
139 #define	DS_MODE_READONLY	0x8
140 #define	DS_MODE_IS_READONLY(x)	((x) & DS_MODE_READONLY)
141 #define	DS_MODE_INCONSISTENT	0x10
142 #define	DS_MODE_IS_INCONSISTENT(x)	((x) & DS_MODE_INCONSISTENT)
143 
144 #define	DS_FIND_SNAPSHOTS	(1<<0)
145 #define	DS_FIND_CHILDREN	(1<<1)
146 
147 /*
148  * The maximum number of bytes that can be accessed as part of one
149  * operation, including metadata.
150  */
151 #define	DMU_MAX_ACCESS (10<<20) /* 10MB */
152 
153 /*
154  * Public routines to create, destroy, open, and close objsets.
155  */
156 int dmu_objset_open(const char *name, dmu_objset_type_t type, int mode,
157     objset_t **osp);
158 void dmu_objset_close(objset_t *os);
159 int dmu_objset_evict_dbufs(objset_t *os, int try);
160 int dmu_objset_create(const char *name, dmu_objset_type_t type,
161     objset_t *clone_parent,
162     void (*func)(objset_t *os, void *arg, dmu_tx_t *tx), void *arg);
163 int dmu_objset_destroy(const char *name);
164 int dmu_snapshots_destroy(char *fsname, char *snapname);
165 int dmu_objset_rollback(const char *name);
166 int dmu_objset_snapshot(char *fsname, char *snapname, boolean_t recursive);
167 int dmu_objset_rename(const char *name, const char *newname);
168 int dmu_objset_find(char *name, int func(char *, void *), void *arg,
169     int flags);
170 void dmu_objset_byteswap(void *buf, size_t size);
171 
172 typedef struct dmu_buf {
173 	uint64_t db_object;		/* object that this buffer is part of */
174 	uint64_t db_offset;		/* byte offset in this object */
175 	uint64_t db_size;		/* size of buffer in bytes */
176 	void *db_data;			/* data in buffer */
177 } dmu_buf_t;
178 
179 typedef void dmu_buf_evict_func_t(struct dmu_buf *db, void *user_ptr);
180 
181 /*
182  * Callback function to perform byte swapping on a block.
183  */
184 typedef void dmu_byteswap_func_t(void *buf, size_t size);
185 
186 /*
187  * The names of zap entries in the DIRECTORY_OBJECT of the MOS.
188  */
189 #define	DMU_POOL_DIRECTORY_OBJECT	1
190 #define	DMU_POOL_CONFIG			"config"
191 #define	DMU_POOL_ROOT_DATASET		"root_dataset"
192 #define	DMU_POOL_SYNC_BPLIST		"sync_bplist"
193 #define	DMU_POOL_ERRLOG_SCRUB		"errlog_scrub"
194 #define	DMU_POOL_ERRLOG_LAST		"errlog_last"
195 #define	DMU_POOL_SPARES			"spares"
196 #define	DMU_POOL_DEFLATE		"deflate"
197 #define	DMU_POOL_HISTORY		"history"
198 #define	DMU_POOL_PROPS			"pool_props"
199 
200 /*
201  * Allocate an object from this objset.  The range of object numbers
202  * available is (0, DN_MAX_OBJECT).  Object 0 is the meta-dnode.
203  *
204  * The transaction must be assigned to a txg.  The newly allocated
205  * object will be "held" in the transaction (ie. you can modify the
206  * newly allocated object in this transaction).
207  *
208  * dmu_object_alloc() chooses an object and returns it in *objectp.
209  *
210  * dmu_object_claim() allocates a specific object number.  If that
211  * number is already allocated, it fails and returns EEXIST.
212  *
213  * Return 0 on success, or ENOSPC or EEXIST as specified above.
214  */
215 uint64_t dmu_object_alloc(objset_t *os, dmu_object_type_t ot,
216     int blocksize, dmu_object_type_t bonus_type, int bonus_len, dmu_tx_t *tx);
217 int dmu_object_claim(objset_t *os, uint64_t object, dmu_object_type_t ot,
218     int blocksize, dmu_object_type_t bonus_type, int bonus_len, dmu_tx_t *tx);
219 int dmu_object_reclaim(objset_t *os, uint64_t object, dmu_object_type_t ot,
220     int blocksize, dmu_object_type_t bonustype, int bonuslen, dmu_tx_t *tx);
221 
222 /*
223  * Free an object from this objset.
224  *
225  * The object's data will be freed as well (ie. you don't need to call
226  * dmu_free(object, 0, -1, tx)).
227  *
228  * The object need not be held in the transaction.
229  *
230  * If there are any holds on this object's buffers (via dmu_buf_hold()),
231  * or tx holds on the object (via dmu_tx_hold_object()), you can not
232  * free it; it fails and returns EBUSY.
233  *
234  * If the object is not allocated, it fails and returns ENOENT.
235  *
236  * Return 0 on success, or EBUSY or ENOENT as specified above.
237  */
238 int dmu_object_free(objset_t *os, uint64_t object, dmu_tx_t *tx);
239 
240 /*
241  * Find the next allocated or free object.
242  *
243  * The objectp parameter is in-out.  It will be updated to be the next
244  * object which is allocated.  Ignore objects which have not been
245  * modified since txg.
246  *
247  * XXX Can only be called on a objset with no dirty data.
248  *
249  * Returns 0 on success, or ENOENT if there are no more objects.
250  */
251 int dmu_object_next(objset_t *os, uint64_t *objectp,
252     boolean_t hole, uint64_t txg);
253 
254 /*
255  * Set the data blocksize for an object.
256  *
257  * The object cannot have any blocks allcated beyond the first.  If
258  * the first block is allocated already, the new size must be greater
259  * than the current block size.  If these conditions are not met,
260  * ENOTSUP will be returned.
261  *
262  * Returns 0 on success, or EBUSY if there are any holds on the object
263  * contents, or ENOTSUP as described above.
264  */
265 int dmu_object_set_blocksize(objset_t *os, uint64_t object, uint64_t size,
266     int ibs, dmu_tx_t *tx);
267 
268 /*
269  * Set the checksum property on a dnode.  The new checksum algorithm will
270  * apply to all newly written blocks; existing blocks will not be affected.
271  */
272 void dmu_object_set_checksum(objset_t *os, uint64_t object, uint8_t checksum,
273     dmu_tx_t *tx);
274 
275 /*
276  * Set the compress property on a dnode.  The new compression algorithm will
277  * apply to all newly written blocks; existing blocks will not be affected.
278  */
279 void dmu_object_set_compress(objset_t *os, uint64_t object, uint8_t compress,
280     dmu_tx_t *tx);
281 
282 /*
283  * Decide how many copies of a given block we should make.  Can be from
284  * 1 to SPA_DVAS_PER_BP.
285  */
286 int dmu_get_replication_level(struct objset_impl *, struct zbookmark *zb,
287     dmu_object_type_t ot);
288 /*
289  * The bonus data is accessed more or less like a regular buffer.
290  * You must dmu_bonus_hold() to get the buffer, which will give you a
291  * dmu_buf_t with db_offset==-1ULL, and db_size = the size of the bonus
292  * data.  As with any normal buffer, you must call dmu_buf_read() to
293  * read db_data, dmu_buf_will_dirty() before modifying it, and the
294  * object must be held in an assigned transaction before calling
295  * dmu_buf_will_dirty.  You may use dmu_buf_set_user() on the bonus
296  * buffer as well.  You must release your hold with dmu_buf_rele().
297  */
298 int dmu_bonus_hold(objset_t *os, uint64_t object, void *tag, dmu_buf_t **);
299 int dmu_bonus_max(void);
300 
301 /*
302  * Obtain the DMU buffer from the specified object which contains the
303  * specified offset.  dmu_buf_hold() puts a "hold" on the buffer, so
304  * that it will remain in memory.  You must release the hold with
305  * dmu_buf_rele().  You musn't access the dmu_buf_t after releasing your
306  * hold.  You must have a hold on any dmu_buf_t* you pass to the DMU.
307  *
308  * You must call dmu_buf_read, dmu_buf_will_dirty, or dmu_buf_will_fill
309  * on the returned buffer before reading or writing the buffer's
310  * db_data.  The comments for those routines describe what particular
311  * operations are valid after calling them.
312  *
313  * The object number must be a valid, allocated object number.
314  */
315 int dmu_buf_hold(objset_t *os, uint64_t object, uint64_t offset,
316     void *tag, dmu_buf_t **);
317 void dmu_buf_add_ref(dmu_buf_t *db, void* tag);
318 void dmu_buf_rele(dmu_buf_t *db, void *tag);
319 uint64_t dmu_buf_refcount(dmu_buf_t *db);
320 
321 /*
322  * dmu_buf_hold_array holds the DMU buffers which contain all bytes in a
323  * range of an object.  A pointer to an array of dmu_buf_t*'s is
324  * returned (in *dbpp).
325  *
326  * dmu_buf_rele_array releases the hold on an array of dmu_buf_t*'s, and
327  * frees the array.  The hold on the array of buffers MUST be released
328  * with dmu_buf_rele_array.  You can NOT release the hold on each buffer
329  * individually with dmu_buf_rele.
330  */
331 int dmu_buf_hold_array_by_bonus(dmu_buf_t *db, uint64_t offset,
332     uint64_t length, int read, void *tag, int *numbufsp, dmu_buf_t ***dbpp);
333 void dmu_buf_rele_array(dmu_buf_t **, int numbufs, void *tag);
334 
335 /*
336  * Returns NULL on success, or the existing user ptr if it's already
337  * been set.
338  *
339  * user_ptr is for use by the user and can be obtained via dmu_buf_get_user().
340  *
341  * user_data_ptr_ptr should be NULL, or a pointer to a pointer which
342  * will be set to db->db_data when you are allowed to access it.  Note
343  * that db->db_data (the pointer) can change when you do dmu_buf_read(),
344  * dmu_buf_tryupgrade(), dmu_buf_will_dirty(), or dmu_buf_will_fill().
345  * *user_data_ptr_ptr will be set to the new value when it changes.
346  *
347  * If non-NULL, pageout func will be called when this buffer is being
348  * excised from the cache, so that you can clean up the data structure
349  * pointed to by user_ptr.
350  *
351  * dmu_evict_user() will call the pageout func for all buffers in a
352  * objset with a given pageout func.
353  */
354 void *dmu_buf_set_user(dmu_buf_t *db, void *user_ptr, void *user_data_ptr_ptr,
355     dmu_buf_evict_func_t *pageout_func);
356 /*
357  * set_user_ie is the same as set_user, but request immediate eviction
358  * when hold count goes to zero.
359  */
360 void *dmu_buf_set_user_ie(dmu_buf_t *db, void *user_ptr,
361     void *user_data_ptr_ptr, dmu_buf_evict_func_t *pageout_func);
362 void *dmu_buf_update_user(dmu_buf_t *db_fake, void *old_user_ptr,
363     void *user_ptr, void *user_data_ptr_ptr,
364     dmu_buf_evict_func_t *pageout_func);
365 void dmu_evict_user(objset_t *os, dmu_buf_evict_func_t *func);
366 
367 /*
368  * Returns the user_ptr set with dmu_buf_set_user(), or NULL if not set.
369  */
370 void *dmu_buf_get_user(dmu_buf_t *db);
371 
372 /*
373  * Indicate that you are going to modify the buffer's data (db_data).
374  *
375  * The transaction (tx) must be assigned to a txg (ie. you've called
376  * dmu_tx_assign()).  The buffer's object must be held in the tx
377  * (ie. you've called dmu_tx_hold_object(tx, db->db_object)).
378  */
379 void dmu_buf_will_dirty(dmu_buf_t *db, dmu_tx_t *tx);
380 
381 /*
382  * You must create a transaction, then hold the objects which you will
383  * (or might) modify as part of this transaction.  Then you must assign
384  * the transaction to a transaction group.  Once the transaction has
385  * been assigned, you can modify buffers which belong to held objects as
386  * part of this transaction.  You can't modify buffers before the
387  * transaction has been assigned; you can't modify buffers which don't
388  * belong to objects which this transaction holds; you can't hold
389  * objects once the transaction has been assigned.  You may hold an
390  * object which you are going to free (with dmu_object_free()), but you
391  * don't have to.
392  *
393  * You can abort the transaction before it has been assigned.
394  *
395  * Note that you may hold buffers (with dmu_buf_hold) at any time,
396  * regardless of transaction state.
397  */
398 
399 #define	DMU_NEW_OBJECT	(-1ULL)
400 #define	DMU_OBJECT_END	(-1ULL)
401 
402 dmu_tx_t *dmu_tx_create(objset_t *os);
403 void dmu_tx_hold_write(dmu_tx_t *tx, uint64_t object, uint64_t off, int len);
404 void dmu_tx_hold_free(dmu_tx_t *tx, uint64_t object, uint64_t off,
405     uint64_t len);
406 void dmu_tx_hold_zap(dmu_tx_t *tx, uint64_t object, int add, char *name);
407 void dmu_tx_hold_bonus(dmu_tx_t *tx, uint64_t object);
408 void dmu_tx_abort(dmu_tx_t *tx);
409 int dmu_tx_assign(dmu_tx_t *tx, uint64_t txg_how);
410 void dmu_tx_wait(dmu_tx_t *tx);
411 void dmu_tx_commit(dmu_tx_t *tx);
412 
413 /*
414  * Free up the data blocks for a defined range of a file.  If size is
415  * zero, the range from offset to end-of-file is freed.
416  */
417 int dmu_free_range(objset_t *os, uint64_t object, uint64_t offset,
418 	uint64_t size, dmu_tx_t *tx);
419 
420 /*
421  * Convenience functions.
422  *
423  * Canfail routines will return 0 on success, or an errno if there is a
424  * nonrecoverable I/O error.
425  */
426 int dmu_read(objset_t *os, uint64_t object, uint64_t offset, uint64_t size,
427 	void *buf);
428 void dmu_write(objset_t *os, uint64_t object, uint64_t offset, uint64_t size,
429 	const void *buf, dmu_tx_t *tx);
430 int dmu_read_uio(objset_t *os, uint64_t object, struct uio *uio, uint64_t size);
431 int dmu_write_uio(objset_t *os, uint64_t object, struct uio *uio, uint64_t size,
432     dmu_tx_t *tx);
433 int dmu_write_pages(objset_t *os, uint64_t object, uint64_t offset,
434     uint64_t size, struct page *pp, dmu_tx_t *tx);
435 
436 extern int zfs_prefetch_disable;
437 
438 /*
439  * Asynchronously try to read in the data.
440  */
441 void dmu_prefetch(objset_t *os, uint64_t object, uint64_t offset,
442     uint64_t len);
443 
444 typedef struct dmu_object_info {
445 	/* All sizes are in bytes. */
446 	uint32_t doi_data_block_size;
447 	uint32_t doi_metadata_block_size;
448 	uint64_t doi_bonus_size;
449 	dmu_object_type_t doi_type;
450 	dmu_object_type_t doi_bonus_type;
451 	uint8_t doi_indirection;		/* 2 = dnode->indirect->data */
452 	uint8_t doi_checksum;
453 	uint8_t doi_compress;
454 	uint8_t doi_pad[5];
455 	/* Values below are number of 512-byte blocks. */
456 	uint64_t doi_physical_blks;		/* data + metadata */
457 	uint64_t doi_max_block_offset;
458 } dmu_object_info_t;
459 
460 typedef struct dmu_object_type_info {
461 	dmu_byteswap_func_t	*ot_byteswap;
462 	boolean_t		ot_metadata;
463 	char			*ot_name;
464 } dmu_object_type_info_t;
465 
466 extern const dmu_object_type_info_t dmu_ot[DMU_OT_NUMTYPES];
467 
468 /*
469  * Get information on a DMU object.
470  *
471  * Return 0 on success or ENOENT if object is not allocated.
472  *
473  * If doi is NULL, just indicates whether the object exists.
474  */
475 int dmu_object_info(objset_t *os, uint64_t object, dmu_object_info_t *doi);
476 void dmu_object_info_from_dnode(struct dnode *dn, dmu_object_info_t *doi);
477 void dmu_object_info_from_db(dmu_buf_t *db, dmu_object_info_t *doi);
478 void dmu_object_size_from_db(dmu_buf_t *db, uint32_t *blksize,
479     u_longlong_t *nblk512);
480 
481 typedef struct dmu_objset_stats {
482 	uint64_t dds_num_clones; /* number of clones of this */
483 	uint64_t dds_creation_txg;
484 	dmu_objset_type_t dds_type;
485 	uint8_t dds_is_snapshot;
486 	uint8_t dds_inconsistent;
487 	char dds_clone_of[MAXNAMELEN];
488 } dmu_objset_stats_t;
489 
490 /*
491  * Get stats on a dataset.
492  */
493 void dmu_objset_fast_stat(objset_t *os, dmu_objset_stats_t *stat);
494 
495 /*
496  * Add entries to the nvlist for all the objset's properties.  See
497  * zfs_prop_table[] and zfs(1m) for details on the properties.
498  */
499 void dmu_objset_stats(objset_t *os, struct nvlist *nv);
500 
501 /*
502  * Get the space usage statistics for statvfs().
503  *
504  * refdbytes is the amount of space "referenced" by this objset.
505  * availbytes is the amount of space available to this objset, taking
506  * into account quotas & reservations, assuming that no other objsets
507  * use the space first.  These values correspond to the 'referenced' and
508  * 'available' properties, described in the zfs(1m) manpage.
509  *
510  * usedobjs and availobjs are the number of objects currently allocated,
511  * and available.
512  */
513 void dmu_objset_space(objset_t *os, uint64_t *refdbytesp, uint64_t *availbytesp,
514     uint64_t *usedobjsp, uint64_t *availobjsp);
515 
516 /*
517  * The fsid_guid is a 56-bit ID that can change to avoid collisions.
518  * (Contrast with the ds_guid which is a 64-bit ID that will never
519  * change, so there is a small probability that it will collide.)
520  */
521 uint64_t dmu_objset_fsid_guid(objset_t *os);
522 
523 int dmu_objset_is_snapshot(objset_t *os);
524 
525 extern struct spa *dmu_objset_spa(objset_t *os);
526 extern struct zilog *dmu_objset_zil(objset_t *os);
527 extern struct dsl_pool *dmu_objset_pool(objset_t *os);
528 extern struct dsl_dataset *dmu_objset_ds(objset_t *os);
529 extern void dmu_objset_name(objset_t *os, char *buf);
530 extern dmu_objset_type_t dmu_objset_type(objset_t *os);
531 extern uint64_t dmu_objset_id(objset_t *os);
532 extern int dmu_snapshot_list_next(objset_t *os, int namelen, char *name,
533     uint64_t *id, uint64_t *offp);
534 extern int dmu_dir_list_next(objset_t *os, int namelen, char *name,
535     uint64_t *idp, uint64_t *offp);
536 
537 /*
538  * Return the txg number for the given assigned transaction.
539  */
540 uint64_t dmu_tx_get_txg(dmu_tx_t *tx);
541 
542 /*
543  * Synchronous write.
544  * If a parent zio is provided this function initiates a write on the
545  * provided buffer as a child of the parent zio.
546  * In the absense of a parent zio, the write is completed synchronously.
547  * At write completion, blk is filled with the bp of the written block.
548  * Note that while the data covered by this function will be on stable
549  * storage when the write completes this new data does not become a
550  * permanent part of the file until the associated transaction commits.
551  */
552 typedef void dmu_sync_cb_t(dmu_buf_t *db, void *arg);
553 int dmu_sync(struct zio *zio, dmu_buf_t *db,
554     struct blkptr *bp, uint64_t txg, dmu_sync_cb_t *done, void *arg);
555 
556 /*
557  * Find the next hole or data block in file starting at *off
558  * Return found offset in *off. Return ESRCH for end of file.
559  */
560 int dmu_offset_next(objset_t *os, uint64_t object, boolean_t hole,
561     uint64_t *off);
562 
563 /*
564  * Initial setup and final teardown.
565  */
566 extern void dmu_init(void);
567 extern void dmu_fini(void);
568 
569 typedef void (*dmu_traverse_cb_t)(objset_t *os, void *arg, struct blkptr *bp,
570     uint64_t object, uint64_t offset, int len);
571 void dmu_traverse_objset(objset_t *os, uint64_t txg_start,
572     dmu_traverse_cb_t cb, void *arg);
573 
574 int dmu_sendbackup(objset_t *tosnap, objset_t *fromsnap, struct vnode *vp);
575 int dmu_recvbackup(char *tosnap, struct drr_begin *drrb, uint64_t *sizep,
576     boolean_t force, struct vnode *vp, uint64_t voffset);
577 
578 /* CRC64 table */
579 #define	ZFS_CRC64_POLY	0xC96C5795D7870F42ULL	/* ECMA-182, reflected form */
580 extern uint64_t zfs_crc64_table[256];
581 
582 #ifdef	__cplusplus
583 }
584 #endif
585 
586 #endif	/* _SYS_DMU_H */
587