xref: /illumos-gate/usr/src/uts/common/fs/zfs/sys/dmu.h (revision 416e0cd82df71e380f21199abde8c5f7a18bac51)
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 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 
64 typedef struct objset objset_t;
65 typedef struct dmu_tx dmu_tx_t;
66 typedef struct dsl_dir dsl_dir_t;
67 
68 typedef enum dmu_object_type {
69 	DMU_OT_NONE,
70 	/* general: */
71 	DMU_OT_OBJECT_DIRECTORY,	/* ZAP */
72 	DMU_OT_OBJECT_ARRAY,		/* UINT64 */
73 	DMU_OT_PACKED_NVLIST,		/* UINT8 (XDR by nvlist_pack/unpack) */
74 	DMU_OT_PACKED_NVLIST_SIZE,	/* UINT64 */
75 	DMU_OT_BPLIST,			/* UINT64 */
76 	DMU_OT_BPLIST_HDR,		/* UINT64 */
77 	/* spa: */
78 	DMU_OT_SPACE_MAP_HEADER,	/* UINT64 */
79 	DMU_OT_SPACE_MAP,		/* UINT64 */
80 	/* zil: */
81 	DMU_OT_INTENT_LOG,		/* UINT64 */
82 	/* dmu: */
83 	DMU_OT_DNODE,			/* DNODE */
84 	DMU_OT_OBJSET,			/* OBJSET */
85 	/* dsl: */
86 	DMU_OT_DSL_DIR,			/* UINT64 */
87 	DMU_OT_DSL_DIR_CHILD_MAP,	/* ZAP */
88 	DMU_OT_DSL_DS_SNAP_MAP,		/* ZAP */
89 	DMU_OT_DSL_PROPS,		/* ZAP */
90 	DMU_OT_DSL_DATASET,		/* UINT64 */
91 	/* zpl: */
92 	DMU_OT_ZNODE,			/* ZNODE */
93 	DMU_OT_ACL,			/* ACL */
94 	DMU_OT_PLAIN_FILE_CONTENTS,	/* UINT8 */
95 	DMU_OT_DIRECTORY_CONTENTS,	/* ZAP */
96 	DMU_OT_MASTER_NODE,		/* ZAP */
97 	DMU_OT_DELETE_QUEUE,		/* ZAP */
98 	/* zvol: */
99 	DMU_OT_ZVOL,			/* UINT8 */
100 	DMU_OT_ZVOL_PROP,		/* ZAP */
101 	/* other; for testing only! */
102 	DMU_OT_PLAIN_OTHER,		/* UINT8 */
103 	DMU_OT_UINT64_OTHER,		/* UINT64 */
104 	DMU_OT_ZAP_OTHER,		/* ZAP */
105 	/* new object types: */
106 	DMU_OT_ERROR_LOG,		/* ZAP */
107 	DMU_OT_SPA_HISTORY,		/* UINT8 */
108 	DMU_OT_SPA_HISTORY_OFFSETS,	/* spa_his_phys_t */
109 
110 	DMU_OT_NUMTYPES
111 } dmu_object_type_t;
112 
113 typedef enum dmu_objset_type {
114 	DMU_OST_NONE,
115 	DMU_OST_META,
116 	DMU_OST_ZFS,
117 	DMU_OST_ZVOL,
118 	DMU_OST_OTHER,			/* For testing only! */
119 	DMU_OST_ANY,			/* Be careful! */
120 	DMU_OST_NUMTYPES
121 } dmu_objset_type_t;
122 
123 void byteswap_uint64_array(void *buf, size_t size);
124 void byteswap_uint32_array(void *buf, size_t size);
125 void byteswap_uint16_array(void *buf, size_t size);
126 void byteswap_uint8_array(void *buf, size_t size);
127 void zap_byteswap(void *buf, size_t size);
128 void zfs_acl_byteswap(void *buf, size_t size);
129 void zfs_znode_byteswap(void *buf, size_t size);
130 
131 #define	DS_MODE_NONE		0	/* invalid, to aid debugging */
132 #define	DS_MODE_STANDARD	1	/* normal access, no special needs */
133 #define	DS_MODE_PRIMARY		2	/* the "main" access, e.g. a mount */
134 #define	DS_MODE_EXCLUSIVE	3	/* exclusive access, e.g. to destroy */
135 #define	DS_MODE_LEVELS		4
136 #define	DS_MODE_LEVEL(x)	((x) & (DS_MODE_LEVELS - 1))
137 #define	DS_MODE_READONLY	0x8
138 #define	DS_MODE_IS_READONLY(x)	((x) & DS_MODE_READONLY)
139 #define	DS_MODE_INCONSISTENT	0x10
140 #define	DS_MODE_IS_INCONSISTENT(x)	((x) & DS_MODE_INCONSISTENT)
141 
142 #define	DS_FIND_SNAPSHOTS	(1<<0)
143 #define	DS_FIND_CHILDREN	(1<<1)
144 
145 /*
146  * The maximum number of bytes that can be accessed as part of one
147  * operation, including metadata.
148  */
149 #define	DMU_MAX_ACCESS (10<<20) /* 10MB */
150 
151 /*
152  * Public routines to create, destroy, open, and close objsets.
153  */
154 int dmu_objset_open(const char *name, dmu_objset_type_t type, int mode,
155     objset_t **osp);
156 void dmu_objset_close(objset_t *os);
157 int dmu_objset_evict_dbufs(objset_t *os, int try);
158 int dmu_objset_create(const char *name, dmu_objset_type_t type,
159     objset_t *clone_parent,
160     void (*func)(objset_t *os, void *arg, dmu_tx_t *tx), void *arg);
161 int dmu_objset_destroy(const char *name);
162 int dmu_snapshots_destroy(char *fsname, char *snapname);
163 int dmu_objset_rollback(const char *name);
164 int dmu_objset_snapshot(char *fsname, char *snapname, boolean_t recursive);
165 int dmu_objset_rename(const char *name, const char *newname);
166 int dmu_objset_find(char *name, int func(char *, void *), void *arg,
167     int flags);
168 void dmu_objset_byteswap(void *buf, size_t size);
169 
170 typedef struct dmu_buf {
171 	uint64_t db_object;		/* object that this buffer is part of */
172 	uint64_t db_offset;		/* byte offset in this object */
173 	uint64_t db_size;		/* size of buffer in bytes */
174 	void *db_data;			/* data in buffer */
175 } dmu_buf_t;
176 
177 typedef void dmu_buf_evict_func_t(struct dmu_buf *db, void *user_ptr);
178 
179 /*
180  * Callback function to perform byte swapping on a block.
181  */
182 typedef void dmu_byteswap_func_t(void *buf, size_t size);
183 
184 /*
185  * The names of zap entries in the DIRECTORY_OBJECT of the MOS.
186  */
187 #define	DMU_POOL_DIRECTORY_OBJECT	1
188 #define	DMU_POOL_CONFIG			"config"
189 #define	DMU_POOL_ROOT_DATASET		"root_dataset"
190 #define	DMU_POOL_SYNC_BPLIST		"sync_bplist"
191 #define	DMU_POOL_ERRLOG_SCRUB		"errlog_scrub"
192 #define	DMU_POOL_ERRLOG_LAST		"errlog_last"
193 #define	DMU_POOL_SPARES			"spares"
194 #define	DMU_POOL_DEFLATE		"deflate"
195 #define	DMU_POOL_HISTORY		"history"
196 
197 /*
198  * Allocate an object from this objset.  The range of object numbers
199  * available is (0, DN_MAX_OBJECT).  Object 0 is the meta-dnode.
200  *
201  * The transaction must be assigned to a txg.  The newly allocated
202  * object will be "held" in the transaction (ie. you can modify the
203  * newly allocated object in this transaction).
204  *
205  * dmu_object_alloc() chooses an object and returns it in *objectp.
206  *
207  * dmu_object_claim() allocates a specific object number.  If that
208  * number is already allocated, it fails and returns EEXIST.
209  *
210  * Return 0 on success, or ENOSPC or EEXIST as specified above.
211  */
212 uint64_t dmu_object_alloc(objset_t *os, 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_claim(objset_t *os, uint64_t object, dmu_object_type_t ot,
215     int blocksize, dmu_object_type_t bonus_type, int bonus_len, dmu_tx_t *tx);
216 int dmu_object_reclaim(objset_t *os, uint64_t object, dmu_object_type_t ot,
217     int blocksize, dmu_object_type_t bonustype, int bonuslen, dmu_tx_t *tx);
218 
219 /*
220  * Free an object from this objset.
221  *
222  * The object's data will be freed as well (ie. you don't need to call
223  * dmu_free(object, 0, -1, tx)).
224  *
225  * The object need not be held in the transaction.
226  *
227  * If there are any holds on this object's buffers (via dmu_buf_hold()),
228  * or tx holds on the object (via dmu_tx_hold_object()), you can not
229  * free it; it fails and returns EBUSY.
230  *
231  * If the object is not allocated, it fails and returns ENOENT.
232  *
233  * Return 0 on success, or EBUSY or ENOENT as specified above.
234  */
235 int dmu_object_free(objset_t *os, uint64_t object, dmu_tx_t *tx);
236 
237 /*
238  * Find the next allocated or free object.
239  *
240  * The objectp parameter is in-out.  It will be updated to be the next
241  * object which is allocated.
242  *
243  * XXX Can only be called on a objset with no dirty data.
244  *
245  * Returns 0 on success, or ENOENT if there are no more objects.
246  */
247 int dmu_object_next(objset_t *os, uint64_t *objectp, boolean_t hole);
248 
249 /*
250  * Set the data blocksize for an object.
251  *
252  * The object cannot have any blocks allcated beyond the first.  If
253  * the first block is allocated already, the new size must be greater
254  * than the current block size.  If these conditions are not met,
255  * ENOTSUP will be returned.
256  *
257  * Returns 0 on success, or EBUSY if there are any holds on the object
258  * contents, or ENOTSUP as described above.
259  */
260 int dmu_object_set_blocksize(objset_t *os, uint64_t object, uint64_t size,
261     int ibs, dmu_tx_t *tx);
262 
263 /*
264  * Set the checksum property on a dnode.  The new checksum algorithm will
265  * apply to all newly written blocks; existing blocks will not be affected.
266  */
267 void dmu_object_set_checksum(objset_t *os, uint64_t object, uint8_t checksum,
268     dmu_tx_t *tx);
269 
270 /*
271  * Set the compress property on a dnode.  The new compression algorithm will
272  * apply to all newly written blocks; existing blocks will not be affected.
273  */
274 void dmu_object_set_compress(objset_t *os, uint64_t object, uint8_t compress,
275     dmu_tx_t *tx);
276 
277 /*
278  * Decide how many copies of a given block we should make.  Can be from
279  * 1 to SPA_DVAS_PER_BP.
280  */
281 int dmu_get_replication_level(struct spa *spa, struct zbookmark *zb,
282     dmu_object_type_t ot);
283 /*
284  * The bonus data is accessed more or less like a regular buffer.
285  * You must dmu_bonus_hold() to get the buffer, which will give you a
286  * dmu_buf_t with db_offset==-1ULL, and db_size = the size of the bonus
287  * data.  As with any normal buffer, you must call dmu_buf_read() to
288  * read db_data, dmu_buf_will_dirty() before modifying it, and the
289  * object must be held in an assigned transaction before calling
290  * dmu_buf_will_dirty.  You may use dmu_buf_set_user() on the bonus
291  * buffer as well.  You must release your hold with dmu_buf_rele().
292  */
293 int dmu_bonus_hold(objset_t *os, uint64_t object, void *tag, dmu_buf_t **);
294 int dmu_bonus_max(void);
295 
296 /*
297  * Obtain the DMU buffer from the specified object which contains the
298  * specified offset.  dmu_buf_hold() puts a "hold" on the buffer, so
299  * that it will remain in memory.  You must release the hold with
300  * dmu_buf_rele().  You musn't access the dmu_buf_t after releasing your
301  * hold.  You must have a hold on any dmu_buf_t* you pass to the DMU.
302  *
303  * You must call dmu_buf_read, dmu_buf_will_dirty, or dmu_buf_will_fill
304  * on the returned buffer before reading or writing the buffer's
305  * db_data.  The comments for those routines describe what particular
306  * operations are valid after calling them.
307  *
308  * The object number must be a valid, allocated object number.
309  */
310 int dmu_buf_hold(objset_t *os, uint64_t object, uint64_t offset,
311     void *tag, dmu_buf_t **);
312 void dmu_buf_add_ref(dmu_buf_t *db, void* tag);
313 void dmu_buf_rele(dmu_buf_t *db, void *tag);
314 uint64_t dmu_buf_refcount(dmu_buf_t *db);
315 
316 /*
317  * dmu_buf_hold_array holds the DMU buffers which contain all bytes in a
318  * range of an object.  A pointer to an array of dmu_buf_t*'s is
319  * returned (in *dbpp).
320  *
321  * dmu_buf_rele_array releases the hold on an array of dmu_buf_t*'s, and
322  * frees the array.  The hold on the array of buffers MUST be released
323  * with dmu_buf_rele_array.  You can NOT release the hold on each buffer
324  * individually with dmu_buf_rele.
325  */
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 /*
363  * Returns the user_ptr set with dmu_buf_set_user(), or NULL if not set.
364  */
365 void *dmu_buf_get_user(dmu_buf_t *db);
366 
367 /*
368  * Indicate that you are going to modify the buffer's data (db_data).
369  *
370  * The transaction (tx) must be assigned to a txg (ie. you've called
371  * dmu_tx_assign()).  The buffer's object must be held in the tx
372  * (ie. you've called dmu_tx_hold_object(tx, db->db_object)).
373  */
374 void dmu_buf_will_dirty(dmu_buf_t *db, dmu_tx_t *tx);
375 
376 /*
377  * You must create a transaction, then hold the objects which you will
378  * (or might) modify as part of this transaction.  Then you must assign
379  * the transaction to a transaction group.  Once the transaction has
380  * been assigned, you can modify buffers which belong to held objects as
381  * part of this transaction.  You can't modify buffers before the
382  * transaction has been assigned; you can't modify buffers which don't
383  * belong to objects which this transaction holds; you can't hold
384  * objects once the transaction has been assigned.  You may hold an
385  * object which you are going to free (with dmu_object_free()), but you
386  * don't have to.
387  *
388  * You can abort the transaction before it has been assigned.
389  *
390  * Note that you may hold buffers (with dmu_buf_hold) at any time,
391  * regardless of transaction state.
392  */
393 
394 #define	DMU_NEW_OBJECT	(-1ULL)
395 #define	DMU_OBJECT_END	(-1ULL)
396 
397 dmu_tx_t *dmu_tx_create(objset_t *os);
398 void dmu_tx_hold_write(dmu_tx_t *tx, uint64_t object, uint64_t off, int len);
399 void dmu_tx_hold_free(dmu_tx_t *tx, uint64_t object, uint64_t off,
400     uint64_t len);
401 void dmu_tx_hold_zap(dmu_tx_t *tx, uint64_t object, int add, char *name);
402 void dmu_tx_hold_bonus(dmu_tx_t *tx, uint64_t object);
403 void dmu_tx_abort(dmu_tx_t *tx);
404 int dmu_tx_assign(dmu_tx_t *tx, uint64_t txg_how);
405 void dmu_tx_wait(dmu_tx_t *tx);
406 void dmu_tx_commit(dmu_tx_t *tx);
407 
408 /*
409  * Free up the data blocks for a defined range of a file.  If size is
410  * zero, the range from offset to end-of-file is freed.
411  */
412 int dmu_free_range(objset_t *os, uint64_t object, uint64_t offset,
413 	uint64_t size, dmu_tx_t *tx);
414 
415 /*
416  * Convenience functions.
417  *
418  * Canfail routines will return 0 on success, or an errno if there is a
419  * nonrecoverable I/O error.
420  */
421 int dmu_read(objset_t *os, uint64_t object, uint64_t offset, uint64_t size,
422 	void *buf);
423 void dmu_write(objset_t *os, uint64_t object, uint64_t offset, uint64_t size,
424 	const void *buf, dmu_tx_t *tx);
425 int dmu_write_uio(objset_t *os, uint64_t object, uint64_t offset, uint64_t size,
426     struct uio *uio, dmu_tx_t *tx);
427 int dmu_write_pages(objset_t *os, uint64_t object, uint64_t offset,
428     uint64_t size, struct page *pp, dmu_tx_t *tx);
429 
430 extern int zfs_prefetch_disable;
431 
432 /*
433  * Asynchronously try to read in the data.
434  */
435 void dmu_prefetch(objset_t *os, uint64_t object, uint64_t offset,
436     uint64_t len);
437 
438 typedef struct dmu_object_info {
439 	/* All sizes are in bytes. */
440 	uint32_t doi_data_block_size;
441 	uint32_t doi_metadata_block_size;
442 	uint64_t doi_bonus_size;
443 	dmu_object_type_t doi_type;
444 	dmu_object_type_t doi_bonus_type;
445 	uint8_t doi_indirection;		/* 2 = dnode->indirect->data */
446 	uint8_t doi_checksum;
447 	uint8_t doi_compress;
448 	uint8_t doi_pad[5];
449 	/* Values below are number of 512-byte blocks. */
450 	uint64_t doi_physical_blks;		/* data + metadata */
451 	uint64_t doi_max_block_offset;
452 } dmu_object_info_t;
453 
454 typedef struct dmu_object_type_info {
455 	dmu_byteswap_func_t	*ot_byteswap;
456 	boolean_t		ot_metadata;
457 	char			*ot_name;
458 } dmu_object_type_info_t;
459 
460 extern const dmu_object_type_info_t dmu_ot[DMU_OT_NUMTYPES];
461 
462 /*
463  * Get information on a DMU object.
464  *
465  * Return 0 on success or ENOENT if object is not allocated.
466  *
467  * If doi is NULL, just indicates whether the object exists.
468  */
469 int dmu_object_info(objset_t *os, uint64_t object, dmu_object_info_t *doi);
470 void dmu_object_info_from_dnode(struct dnode *dn, dmu_object_info_t *doi);
471 void dmu_object_info_from_db(dmu_buf_t *db, dmu_object_info_t *doi);
472 void dmu_object_size_from_db(dmu_buf_t *db, uint32_t *blksize,
473     u_longlong_t *nblk512);
474 
475 typedef struct dmu_objset_stats {
476 	uint64_t dds_num_clones; /* number of clones of this */
477 	uint64_t dds_creation_txg;
478 	dmu_objset_type_t dds_type;
479 	uint8_t dds_is_snapshot;
480 	uint8_t dds_inconsistent;
481 	char dds_clone_of[MAXNAMELEN];
482 } dmu_objset_stats_t;
483 
484 /*
485  * Get stats on a dataset.
486  */
487 void dmu_objset_fast_stat(objset_t *os, dmu_objset_stats_t *stat);
488 
489 /*
490  * Add entries to the nvlist for all the objset's properties.  See
491  * zfs_prop_table[] and zfs(1m) for details on the properties.
492  */
493 void dmu_objset_stats(objset_t *os, struct nvlist *nv);
494 
495 /*
496  * Get the space usage statistics for statvfs().
497  *
498  * refdbytes is the amount of space "referenced" by this objset.
499  * availbytes is the amount of space available to this objset, taking
500  * into account quotas & reservations, assuming that no other objsets
501  * use the space first.  These values correspond to the 'referenced' and
502  * 'available' properties, described in the zfs(1m) manpage.
503  *
504  * usedobjs and availobjs are the number of objects currently allocated,
505  * and available.
506  */
507 void dmu_objset_space(objset_t *os, uint64_t *refdbytesp, uint64_t *availbytesp,
508     uint64_t *usedobjsp, uint64_t *availobjsp);
509 
510 /*
511  * The fsid_guid is a 56-bit ID that can change to avoid collisions.
512  * (Contrast with the ds_guid which is a 64-bit ID that will never
513  * change, so there is a small probability that it will collide.)
514  */
515 uint64_t dmu_objset_fsid_guid(objset_t *os);
516 
517 int dmu_objset_is_snapshot(objset_t *os);
518 
519 extern struct spa *dmu_objset_spa(objset_t *os);
520 extern struct zilog *dmu_objset_zil(objset_t *os);
521 extern struct dsl_pool *dmu_objset_pool(objset_t *os);
522 extern struct dsl_dataset *dmu_objset_ds(objset_t *os);
523 extern void dmu_objset_name(objset_t *os, char *buf);
524 extern dmu_objset_type_t dmu_objset_type(objset_t *os);
525 extern uint64_t dmu_objset_id(objset_t *os);
526 extern int dmu_snapshot_list_next(objset_t *os, int namelen, char *name,
527     uint64_t *id, uint64_t *offp);
528 extern int dmu_dir_list_next(objset_t *os, int namelen, char *name,
529     uint64_t *idp, uint64_t *offp);
530 
531 /*
532  * Return the txg number for the given assigned transaction.
533  */
534 uint64_t dmu_tx_get_txg(dmu_tx_t *tx);
535 
536 /*
537  * Synchronous write.
538  * If a parent zio is provided this function initiates a write on the
539  * provided buffer as a child of the parent zio.
540  * In the absense of a parent zio, the write is completed synchronously.
541  * At write completion, blk is filled with the bp of the written block.
542  * Note that while the data covered by this function will be on stable
543  * storage when the write completes this new data does not become a
544  * permanent part of the file until the associated transaction commits.
545  */
546 typedef void dmu_sync_cb_t(dmu_buf_t *db, void *arg);
547 int dmu_sync(struct zio *zio, dmu_buf_t *db,
548     struct blkptr *bp, uint64_t txg, dmu_sync_cb_t *done, void *arg);
549 
550 /*
551  * Find the next hole or data block in file starting at *off
552  * Return found offset in *off. Return ESRCH for end of file.
553  */
554 int dmu_offset_next(objset_t *os, uint64_t object, boolean_t hole,
555     uint64_t *off);
556 
557 /*
558  * Initial setup and final teardown.
559  */
560 extern void dmu_init(void);
561 extern void dmu_fini(void);
562 
563 typedef void (*dmu_traverse_cb_t)(objset_t *os, void *arg, struct blkptr *bp,
564     uint64_t object, uint64_t offset, int len);
565 void dmu_traverse_objset(objset_t *os, uint64_t txg_start,
566     dmu_traverse_cb_t cb, void *arg);
567 
568 int dmu_sendbackup(objset_t *tosnap, objset_t *fromsnap, struct vnode *vp);
569 int dmu_recvbackup(char *tosnap, struct drr_begin *drrb, uint64_t *sizep,
570     boolean_t force, struct vnode *vp, uint64_t voffset);
571 
572 /* CRC64 table */
573 #define	ZFS_CRC64_POLY	0xC96C5795D7870F42ULL	/* ECMA-182, reflected form */
574 extern uint64_t zfs_crc64_table[256];
575 
576 #ifdef	__cplusplus
577 }
578 #endif
579 
580 #endif	/* _SYS_DMU_H */
581