xref: /titanic_41/usr/src/uts/common/fs/zfs/sys/dmu.h (revision 29949e866e40b95795203f3ee46f44a197c946e4)
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, Version 1.0 only
6  * (the "License").  You may not use this file except in compliance
7  * with the License.
8  *
9  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
10  * or http://www.opensolaris.org/os/licensing.
11  * See the License for the specific language governing permissions
12  * and limitations under the License.
13  *
14  * When distributing Covered Code, include this CDDL HEADER in each
15  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
16  * If applicable, add the following below this CDDL HEADER, with the
17  * fields enclosed by brackets "[]" replaced with your own identifying
18  * information: Portions Copyright [yyyy] [name of copyright owner]
19  *
20  * CDDL HEADER END
21  */
22 /*
23  * Copyright 2005 Sun Microsystems, Inc.  All rights reserved.
24  * Use is subject to license terms.
25  */
26 
27 #ifndef	_SYS_DMU_H
28 #define	_SYS_DMU_H
29 
30 #pragma ident	"%Z%%M%	%I%	%E% SMI"
31 
32 /*
33  * This file describes the interface that the DMU provides for its
34  * consumers.
35  *
36  * The DMU also interacts with the SPA.  That interface is described in
37  * dmu_spa.h.
38  */
39 
40 #include <sys/inttypes.h>
41 #include <sys/types.h>
42 #include <sys/param.h>
43 
44 #ifdef	__cplusplus
45 extern "C" {
46 #endif
47 
48 struct uio;
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 
61 typedef struct objset objset_t;
62 typedef struct dmu_tx dmu_tx_t;
63 typedef struct dsl_dir dsl_dir_t;
64 
65 typedef enum dmu_object_type {
66 	DMU_OT_NONE,
67 	/* general: */
68 	DMU_OT_OBJECT_DIRECTORY,	/* ZAP */
69 	DMU_OT_OBJECT_ARRAY,		/* UINT64 */
70 	DMU_OT_PACKED_NVLIST,		/* UINT8 (XDR by nvlist_pack/unpack) */
71 	DMU_OT_PACKED_NVLIST_SIZE,	/* UINT64 */
72 	DMU_OT_BPLIST,			/* UINT64 */
73 	DMU_OT_BPLIST_HDR,		/* UINT64 */
74 	/* spa: */
75 	DMU_OT_SPACE_MAP_HEADER,	/* UINT64 */
76 	DMU_OT_SPACE_MAP,		/* UINT64 */
77 	/* zil: */
78 	DMU_OT_INTENT_LOG,		/* UINT64 */
79 	/* dmu: */
80 	DMU_OT_DNODE,			/* DNODE */
81 	DMU_OT_OBJSET,			/* OBJSET */
82 	/* dsl: */
83 	DMU_OT_DSL_DIR,			/* UINT64 */
84 	DMU_OT_DSL_DIR_CHILD_MAP,	/* ZAP */
85 	DMU_OT_DSL_DS_SNAP_MAP,		/* ZAP */
86 	DMU_OT_DSL_PROPS,		/* ZAP */
87 	DMU_OT_DSL_DATASET,		/* UINT64 */
88 	/* zpl: */
89 	DMU_OT_ZNODE,			/* ZNODE */
90 	DMU_OT_ACL,			/* ACL */
91 	DMU_OT_PLAIN_FILE_CONTENTS,	/* UINT8 */
92 	DMU_OT_DIRECTORY_CONTENTS,	/* ZAP */
93 	DMU_OT_MASTER_NODE,		/* ZAP */
94 	DMU_OT_DELETE_QUEUE,		/* ZAP */
95 	/* zvol: */
96 	DMU_OT_ZVOL,			/* UINT8 */
97 	DMU_OT_ZVOL_PROP,		/* ZAP */
98 	/* other; for testing only! */
99 	DMU_OT_PLAIN_OTHER,		/* UINT8 */
100 	DMU_OT_UINT64_OTHER,		/* UINT64 */
101 	DMU_OT_ZAP_OTHER,		/* ZAP */
102 
103 	DMU_OT_NUMTYPES
104 } dmu_object_type_t;
105 
106 typedef enum dmu_objset_type {
107 	DMU_OST_NONE,
108 	DMU_OST_META,
109 	DMU_OST_ZFS,
110 	DMU_OST_ZVOL,
111 	DMU_OST_OTHER,			/* For testing only! */
112 	DMU_OST_ANY,			/* Be careful! */
113 	DMU_OST_NUMTYPES
114 } dmu_objset_type_t;
115 
116 void byteswap_uint64_array(void *buf, size_t size);
117 void byteswap_uint32_array(void *buf, size_t size);
118 void byteswap_uint16_array(void *buf, size_t size);
119 void byteswap_uint8_array(void *buf, size_t size);
120 void zap_byteswap(void *buf, size_t size);
121 void zfs_acl_byteswap(void *buf, size_t size);
122 void zfs_znode_byteswap(void *buf, size_t size);
123 
124 #define	DS_MODE_NONE		0	/* invalid, to aid debugging */
125 #define	DS_MODE_STANDARD	1	/* normal access, no special needs */
126 #define	DS_MODE_PRIMARY		2	/* the "main" access, e.g. a mount */
127 #define	DS_MODE_EXCLUSIVE	3	/* exclusive access, e.g. to destroy */
128 #define	DS_MODE_LEVELS		4
129 #define	DS_MODE_LEVEL(x)	((x) & (DS_MODE_LEVELS - 1))
130 #define	DS_MODE_READONLY	0x8
131 #define	DS_MODE_IS_READONLY(x)	((x) & DS_MODE_READONLY)
132 #define	DS_MODE_RESTORE		0x10
133 #define	DS_MODE_IS_RESTORE(x)	((x) & DS_MODE_RESTORE)
134 
135 #define	DS_FIND_SNAPSHOTS	0x01
136 
137 /*
138  * The maximum number of bytes that can be accessed as part of one
139  * operation, including metadata.
140  */
141 #define	DMU_MAX_ACCESS (10<<20) /* 10MB */
142 
143 /*
144  * Public routines to create, destroy, open, and close objsets.
145  */
146 int dmu_objset_open(const char *name, dmu_objset_type_t type, int mode,
147     objset_t **osp);
148 void dmu_objset_close(objset_t *os);
149 int dmu_objset_create(const char *name, dmu_objset_type_t type,
150     objset_t *clone_parent,
151     void (*func)(objset_t *os, void *arg, dmu_tx_t *tx), void *arg);
152 int dmu_objset_destroy(const char *name);
153 int dmu_objset_rollback(const char *name);
154 int dmu_objset_rename(const char *name, const char *newname);
155 void dmu_objset_set_quota(objset_t *os, uint64_t quota);
156 uint64_t dmu_objset_get_quota(objset_t *os);
157 int dmu_objset_request_reservation(objset_t *os, uint64_t reservation);
158 void dmu_objset_find(char *name, void func(char *, void *), void *arg,
159     int flags);
160 void dmu_objset_byteswap(void *buf, size_t size);
161 
162 typedef struct dmu_buf {
163 	uint64_t db_object;		/* object that this buffer is part of */
164 	uint64_t db_offset;		/* byte offset in this object */
165 	uint64_t db_size;		/* size of buffer in bytes */
166 	void *db_data;			/* data in buffer */
167 } dmu_buf_t;
168 
169 typedef void dmu_buf_evict_func_t(struct dmu_buf *db, void *user_ptr);
170 
171 /*
172  * Callback function to perform byte swapping on a block.
173  */
174 typedef void dmu_byteswap_func_t(void *buf, size_t size);
175 
176 #define	DMU_POOL_DIRECTORY_OBJECT	1
177 #define	DMU_POOL_CONFIG			"config"
178 #define	DMU_POOL_ROOT_DATASET		"root_dataset"
179 #define	DMU_POOL_SYNC_BPLIST		"sync_bplist"
180 
181 /*
182  * Allocate an object from this objset.  The range of object numbers
183  * available is (0, DN_MAX_OBJECT).  Object 0 is the meta-dnode.
184  *
185  * The transaction must be assigned to a txg.  The newly allocated
186  * object will be "held" in the transaction (ie. you can modify the
187  * newly allocated object in this transaction).
188  *
189  * dmu_object_alloc() chooses an object and returns it in *objectp.
190  *
191  * dmu_object_claim() allocates a specific object number.  If that
192  * number is already allocated, it fails and returns EEXIST.
193  *
194  * Return 0 on success, or ENOSPC or EEXIST as specified above.
195  */
196 uint64_t dmu_object_alloc(objset_t *os, dmu_object_type_t ot,
197     int blocksize, dmu_object_type_t bonus_type, int bonus_len, dmu_tx_t *tx);
198 int dmu_object_claim(objset_t *os, uint64_t object, dmu_object_type_t ot,
199     int blocksize, dmu_object_type_t bonus_type, int bonus_len, dmu_tx_t *tx);
200 int dmu_object_reclaim(objset_t *os, uint64_t object, dmu_object_type_t ot,
201     int blocksize, dmu_object_type_t bonustype, int bonuslen, dmu_tx_t *tx);
202 
203 /*
204  * Free an object from this objset.
205  *
206  * The object's data will be freed as well (ie. you don't need to call
207  * dmu_free(object, 0, -1, tx)).
208  *
209  * The object need not be held in the transaction.
210  *
211  * If there are any holds on this object's buffers (via dmu_buf_hold()),
212  * or tx holds on the object (via dmu_tx_hold_object()), you can not
213  * free it; it fails and returns EBUSY.
214  *
215  * If the object is not allocated, it fails and returns ENOENT.
216  *
217  * Return 0 on success, or EBUSY or ENOENT as specified above.
218  */
219 int dmu_object_free(objset_t *os, uint64_t object, dmu_tx_t *tx);
220 
221 /*
222  * Find the next allocated or free object.
223  *
224  * The objectp parameter is in-out.  It will be updated to be the next
225  * object which is allocated.
226  *
227  * XXX Can only be called on a objset with no dirty data.
228  *
229  * Returns 0 on success, or ENOENT if there are no more objects.
230  */
231 int dmu_object_next(objset_t *os, uint64_t *objectp, boolean_t hole);
232 
233 /*
234  * Set the data blocksize for an object.
235  *
236  * The object cannot have any blocks allcated beyond the first.  If
237  * the first block is allocated already, the new size must be greater
238  * than the current block size.  If these conditions are not met,
239  * ENOTSUP will be returned.
240  *
241  * Returns 0 on success, or EBUSY if there are any holds on the object
242  * contents, or ENOTSUP as described above.
243  */
244 int dmu_object_set_blocksize(objset_t *os, uint64_t object, uint64_t size,
245     int ibs, dmu_tx_t *tx);
246 
247 /*
248  * Set the checksum property on a dnode.  The new checksum algorithm will
249  * apply to all newly written blocks; existing blocks will not be affected.
250  */
251 void dmu_object_set_checksum(objset_t *os, uint64_t object, uint8_t checksum,
252     dmu_tx_t *tx);
253 
254 /*
255  * Set the compress property on a dnode.  The new compression algorithm will
256  * apply to all newly written blocks; existing blocks will not be affected.
257  */
258 void dmu_object_set_compress(objset_t *os, uint64_t object, uint8_t compress,
259     dmu_tx_t *tx);
260 
261 /*
262  * The bonus data is accessed more or less like a regular buffer.
263  * You must dmu_bonus_hold() to get the buffer, which will give you a
264  * dmu_buf_t with db_offset==-1ULL, and db_size = the size of the bonus
265  * data.  As with any normal buffer, you must call dmu_buf_read() to
266  * read db_data, dmu_buf_will_dirty() before modifying it, and the
267  * object must be held in an assigned transaction before calling
268  * dmu_buf_will_dirty.  You may use dmu_buf_set_user() on the bonus
269  * buffer as well.  You must release your hold with dmu_buf_rele().
270  */
271 dmu_buf_t *dmu_bonus_hold(objset_t *os, uint64_t object);
272 dmu_buf_t *dmu_bonus_hold_tag(objset_t *os, uint64_t object, void *tag);
273 int dmu_bonus_max(void);
274 
275 /*
276  * Obtain the DMU buffer from the specified object which contains the
277  * specified offset.  dmu_buf_hold() puts a "hold" on the buffer, so
278  * that it will remain in memory.  You must release the hold with
279  * dmu_buf_rele().  You musn't access the dmu_buf_t after releasing your
280  * hold.  You must have a hold on any dmu_buf_t* you pass to the DMU.
281  *
282  * You must call dmu_buf_read, dmu_buf_will_dirty, or dmu_buf_will_fill
283  * on the returned buffer before reading or writing the buffer's
284  * db_data.  The comments for those routines describe what particular
285  * operations are valid after calling them.
286  *
287  * The object number must be a valid, allocated object number.
288  */
289 dmu_buf_t *dmu_buf_hold(objset_t *os, uint64_t object, uint64_t offset);
290 void dmu_buf_add_ref(dmu_buf_t *db, void* tag);
291 void dmu_buf_remove_ref(dmu_buf_t *db, void* tag);
292 void dmu_buf_rele(dmu_buf_t *db);
293 void dmu_buf_rele_tag(dmu_buf_t *db, void *tag);
294 uint64_t dmu_buf_refcount(dmu_buf_t *db);
295 
296 /*
297  * dmu_buf_hold_array holds the DMU buffers which contain all bytes in a
298  * range of an object.  A pointer to an array of dmu_buf_t*'s is
299  * returned (in *dbpp).
300  *
301  * dmu_buf_rele_array releases the hold on an array of dmu_buf_t*'s, and
302  * frees the array.  The hold on the array of buffers MUST be released
303  * with dmu_buf_rele_array.  You can NOT release the hold on each buffer
304  * individually with dmu_buf_rele.
305  */
306 dmu_buf_t **dmu_buf_hold_array(objset_t *os, uint64_t object,
307     uint64_t offset, uint64_t length, int *numbufs);
308 void dmu_buf_rele_array(dmu_buf_t **, int numbufs);
309 
310 /*
311  * Returns NULL on success, or the existing user ptr if it's already
312  * been set.
313  *
314  * user_ptr is for use by the user and can be obtained via dmu_buf_get_user().
315  *
316  * user_data_ptr_ptr should be NULL, or a pointer to a pointer which
317  * will be set to db->db_data when you are allowed to access it.  Note
318  * that db->db_data (the pointer) can change when you do dmu_buf_read(),
319  * dmu_buf_tryupgrade(), dmu_buf_will_dirty(), or dmu_buf_will_fill().
320  * *user_data_ptr_ptr will be set to the new value when it changes.
321  *
322  * If non-NULL, pageout func will be called when this buffer is being
323  * excised from the cache, so that you can clean up the data structure
324  * pointed to by user_ptr.
325  *
326  * dmu_evict_user() will call the pageout func for all buffers in a
327  * objset with a given pageout func.
328  */
329 void *dmu_buf_set_user(dmu_buf_t *db, void *user_ptr, void *user_data_ptr_ptr,
330     dmu_buf_evict_func_t *pageout_func);
331 /*
332  * set_user_ie is the same as set_user, but request immediate eviction
333  * when hold count goes to zero.
334  */
335 void *dmu_buf_set_user_ie(dmu_buf_t *db, void *user_ptr,
336     void *user_data_ptr_ptr, dmu_buf_evict_func_t *pageout_func);
337 void *dmu_buf_update_user(dmu_buf_t *db_fake, void *old_user_ptr,
338     void *user_ptr, void *user_data_ptr_ptr,
339     dmu_buf_evict_func_t *pageout_func);
340 void dmu_evict_user(objset_t *os, dmu_buf_evict_func_t *func);
341 
342 void dmu_buf_hold_data(dmu_buf_t *db);
343 void dmu_buf_rele_data(dmu_buf_t *db);
344 
345 /*
346  * Returns the user_ptr set with dmu_buf_set_user(), or NULL if not set.
347  */
348 void *dmu_buf_get_user(dmu_buf_t *db);
349 
350 /*
351  * Indicate that you are going to read the buffer's data (db_data).
352  *
353  * This routine will read the data from disk if necessary.
354  *
355  * These routines will return 0 on success, or an errno if there is a
356  * nonrecoverable I/O error.
357  */
358 void dmu_buf_read(dmu_buf_t *db);
359 int dmu_buf_read_canfail(dmu_buf_t *db);
360 void dmu_buf_read_array(dmu_buf_t **dbp, int numbufs);
361 int dmu_buf_read_array_canfail(dmu_buf_t **dbp, int numbufs);
362 
363 /*
364  * Indicate that you are going to modify the buffer's data (db_data).
365  *
366  * The transaction (tx) must be assigned to a txg (ie. you've called
367  * dmu_tx_assign()).  The buffer's object must be held in the tx
368  * (ie. you've called dmu_tx_hold_object(tx, db->db_object)).
369  */
370 void dmu_buf_will_dirty(dmu_buf_t *db, dmu_tx_t *tx);
371 
372 /*
373  * Indicate that you are going to modify the entire contents of the
374  * buffer's data ("fill" it).
375  *
376  * This routine is the same as dmu_buf_will_dirty, except that it won't
377  * read the contents off the disk, so the contents may be uninitialized
378  * and you must overwrite it.
379  *
380  * The transaction (tx) must be assigned to a txg (ie. you've called
381  * dmu_tx_assign()).  The buffer's object must be held in the tx (ie.
382  * you've called dmu_tx_hold_object(tx, db->db_object)).
383  */
384 /* void dmu_buf_will_fill(dmu_buf_t *db, dmu_tx_t *tx); */
385 
386 /*
387  * You must create a transaction, then hold the objects which you will
388  * (or might) modify as part of this transaction.  Then you must assign
389  * the transaction to a transaction group.  Once the transaction has
390  * been assigned, you can modify buffers which belong to held objects as
391  * part of this transaction.  You can't modify buffers before the
392  * transaction has been assigned; you can't modify buffers which don't
393  * belong to objects which this transaction holds; you can't hold
394  * objects once the transaction has been assigned.  You may hold an
395  * object which you are going to free (with dmu_object_free()), but you
396  * don't have to.
397  *
398  * You can abort the transaction before it has been assigned.
399  *
400  * Note that you may hold buffers (with dmu_buf_hold) at any time,
401  * regardless of transaction state.
402  */
403 
404 #define	DMU_NEW_OBJECT	(-1ULL)
405 #define	DMU_OBJECT_END	(-1ULL)
406 
407 dmu_tx_t *dmu_tx_create(objset_t *os);
408 void dmu_tx_hold_write(dmu_tx_t *tx, uint64_t object, uint64_t off, int len);
409 void dmu_tx_hold_free(dmu_tx_t *tx, uint64_t object, uint64_t off,
410     uint64_t len);
411 void dmu_tx_hold_zap(dmu_tx_t *tx, uint64_t object, int ops);
412 void dmu_tx_hold_bonus(dmu_tx_t *tx, uint64_t object);
413 void dmu_tx_abort(dmu_tx_t *tx);
414 int dmu_tx_assign(dmu_tx_t *tx, uint64_t txg_how);
415 void dmu_tx_commit(dmu_tx_t *tx);
416 
417 /*
418  * Free up the data blocks for a defined range of a file.  If size is
419  * zero, the range from offset to end-of-file is freed.
420  */
421 void dmu_free_range(objset_t *os, uint64_t object, uint64_t offset,
422 	uint64_t size, dmu_tx_t *tx);
423 
424 /*
425  * Convenience functions.
426  *
427  * Canfail routines will return 0 on success, or an errno if there is a
428  * nonrecoverable I/O error.
429  */
430 void dmu_read(objset_t *os, uint64_t object, uint64_t offset, uint64_t size,
431 	void *buf);
432 int dmu_read_canfail(objset_t *dd, uint64_t object, uint64_t offset,
433 	uint64_t size, void *buf);
434 void dmu_write(objset_t *os, uint64_t object, uint64_t offset, uint64_t size,
435 	const void *buf, dmu_tx_t *tx);
436 int dmu_write_uio(objset_t *os, uint64_t object, uint64_t offset, uint64_t size,
437     struct uio *uio, dmu_tx_t *tx);
438 
439 /*
440  * Asynchronously try to read in the data.
441  */
442 void dmu_prefetch(objset_t *os, uint64_t object, uint64_t offset,
443     uint64_t len);
444 
445 typedef struct dmu_object_info {
446 	/* All sizes are in bytes. */
447 	uint32_t doi_data_block_size;
448 	uint32_t doi_metadata_block_size;
449 	uint64_t doi_bonus_size;
450 	dmu_object_type_t doi_type;
451 	dmu_object_type_t doi_bonus_type;
452 	uint8_t doi_indirection;		/* 2 = dnode->indirect->data */
453 	uint8_t doi_checksum;
454 	uint8_t doi_compress;
455 	uint8_t doi_pad[5];
456 	/* Values below are number of 512-byte blocks. */
457 	uint64_t doi_physical_blks;		/* data + metadata */
458 	uint64_t doi_max_block_offset;
459 } dmu_object_info_t;
460 
461 typedef struct dmu_object_type_info {
462 	dmu_byteswap_func_t	*ot_byteswap;
463 	boolean_t		ot_metadata;
464 	char			*ot_name;
465 } dmu_object_type_info_t;
466 
467 extern const dmu_object_type_info_t dmu_ot[DMU_OT_NUMTYPES];
468 
469 /*
470  * Get information on a DMU object.
471  *
472  * Return 0 on success or ENOENT if object is not allocated.
473  *
474  * If doi is NULL, just indicates whether the object exists.
475  */
476 int dmu_object_info(objset_t *os, uint64_t object, dmu_object_info_t *doi);
477 void dmu_object_info_from_dnode(struct dnode *dn, dmu_object_info_t *doi);
478 void dmu_object_info_from_db(dmu_buf_t *db, dmu_object_info_t *doi);
479 void dmu_object_size_from_db(dmu_buf_t *db, uint32_t *blksize,
480     u_longlong_t *nblk512);
481 
482 /*
483  * Get the maximum nonzero offset in the object (ie. this offset and all
484  * offsets following are zero).
485  *
486  * XXX Perhaps integrate this with dmu_object_info(), although that
487  * would then have to bring in the indirect blocks.
488  */
489 uint64_t dmu_object_max_nonzero_offset(objset_t *os, uint64_t object);
490 
491 typedef struct dmu_objset_stats {
492 	dmu_objset_type_t dds_type;
493 	uint8_t dds_is_snapshot;
494 	uint8_t dds_is_placeholder;
495 	uint8_t dds_pad[2];
496 
497 	uint64_t dds_creation_time;
498 	uint64_t dds_creation_txg;
499 
500 	char dds_clone_of[MAXNAMELEN];
501 
502 	/* How much data is there in this objset? */
503 
504 	/*
505 	 * Space referenced, taking into account pending writes and
506 	 * frees.  Only relavent to filesystems and snapshots (not
507 	 * collections).
508 	 */
509 	uint64_t dds_space_refd;
510 
511 	/*
512 	 * Space "used", taking into account pending writes and frees, and
513 	 * children's reservations (in bytes).  This is the amount of
514 	 * space that will be freed if this and all dependent items are
515 	 * destroyed (eg. child datasets, objsets, and snapshots).  So
516 	 * for snapshots, this is the amount of space unique to this
517 	 * snapshot.
518 	 */
519 	uint64_t dds_space_used;
520 
521 	/*
522 	 * Compressed and uncompressed bytes consumed.  Does not take
523 	 * into account reservations.  Used for computing compression
524 	 * ratio.
525 	 */
526 	uint64_t dds_compressed_bytes;
527 	uint64_t dds_uncompressed_bytes;
528 
529 	/*
530 	 * The ds_fsid_guid is a 56-bit ID that can change to avoid
531 	 * collisions.  The ds_guid is a 64-bit ID that will never
532 	 * change, so there is a small probability that it will collide.
533 	 */
534 	uint64_t dds_fsid_guid;
535 	uint64_t dds_guid;
536 
537 	uint64_t dds_objects_used;	/* number of objects used */
538 	uint64_t dds_objects_avail;	/* number of objects available */
539 
540 	uint64_t dds_num_clones; /* number of clones of this */
541 
542 	/* The dataset's administratively-set quota, in bytes. */
543 	uint64_t dds_quota;
544 
545 	/* The dataset's administratively-set reservation, in bytes */
546 	uint64_t dds_reserved;
547 
548 	/*
549 	 * The amount of additional space that this dataset can consume.
550 	 * Takes into account quotas & reservations.
551 	 * (Assuming that no other datasets consume it first.)
552 	 */
553 	uint64_t dds_available;
554 
555 	/*
556 	 * Various properties.
557 	 */
558 	uint64_t dds_compression;
559 	uint64_t dds_checksum;
560 	uint64_t dds_zoned;
561 	char dds_compression_setpoint[MAXNAMELEN];
562 	char dds_checksum_setpoint[MAXNAMELEN];
563 	char dds_zoned_setpoint[MAXNAMELEN];
564 	char dds_altroot[MAXPATHLEN];
565 
566 	/* The following are for debugging purposes only */
567 	uint64_t dds_last_txg;
568 	uint64_t dds_dir_obj;
569 	uint64_t dds_objset_obj;
570 	uint64_t dds_clone_of_obj;
571 } dmu_objset_stats_t;
572 
573 /*
574  * Get stats on a dataset.
575  */
576 void dmu_objset_stats(objset_t *os, dmu_objset_stats_t *dds);
577 
578 int dmu_objset_is_snapshot(objset_t *os);
579 
580 extern struct spa *dmu_objset_spa(objset_t *os);
581 extern struct zilog *dmu_objset_zil(objset_t *os);
582 extern struct dsl_pool *dmu_objset_pool(objset_t *os);
583 extern struct dsl_dataset *dmu_objset_ds(objset_t *os);
584 extern void dmu_objset_name(objset_t *os, char *buf);
585 extern dmu_objset_type_t dmu_objset_type(objset_t *os);
586 extern uint64_t dmu_objset_id(objset_t *os);
587 extern int dmu_snapshot_list_next(objset_t *os, int namelen, char *name,
588     uint64_t *id, uint64_t *offp);
589 extern int dmu_dir_list_next(objset_t *os, int namelen, char *name,
590     uint64_t *idp, uint64_t *offp);
591 
592 /*
593  * Return the txg number for the given assigned transaction.
594  */
595 uint64_t dmu_tx_get_txg(dmu_tx_t *tx);
596 
597 /*
598  * Synchronous write.
599  * On success returns 0 and fills in the blk pointed at by bp.
600  * Note that while the data covered by this function will be on stable
601  * storage when the function returns this new data does not become a
602  * permanent part of the file until the associated transaction commits.
603  */
604 int dmu_sync(objset_t *os, uint64_t object, uint64_t offset, uint64_t *blkoff,
605     struct blkptr *bp, uint64_t txg);
606 
607 /*
608  * Find the next hole or data block in file starting at *off
609  * Return found offset in *off. Return ESRCH for end of file.
610  */
611 int dmu_offset_next(objset_t *os, uint64_t object, boolean_t hole,
612     uint64_t *off);
613 
614 /*
615  * Initial setup and final teardown.
616  */
617 extern void dmu_init(void);
618 extern void dmu_fini(void);
619 
620 typedef void (*dmu_traverse_cb_t)(objset_t *os, void *arg, struct blkptr *bp,
621     uint64_t object, uint64_t offset, int len);
622 void dmu_traverse_objset(objset_t *os, uint64_t txg_start,
623     dmu_traverse_cb_t cb, void *arg);
624 
625 int dmu_sendbackup(objset_t *tosnap, objset_t *fromsnap, struct vnode *vp);
626 int dmu_recvbackup(struct drr_begin *drrb, uint64_t *sizep,
627     struct vnode *vp, uint64_t voffset);
628 
629 /* CRC64 table */
630 #define	ZFS_CRC64_POLY	0xC96C5795D7870F42ULL	/* ECMA-182, reflected form */
631 extern uint64_t zfs_crc64_table[256];
632 
633 #ifdef	__cplusplus
634 }
635 #endif
636 
637 #endif	/* _SYS_DMU_H */
638