xref: /titanic_50/usr/src/uts/common/fs/zfs/sys/dmu.h (revision 6aa4fc89ec1cf2cdf7d7c3b9ec059802ac9abe65)
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 /*
23  * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
24  * Copyright (c) 2011, 2014 by Delphix. All rights reserved.
25  * Copyright 2011 Nexenta Systems, Inc. All rights reserved.
26  * Copyright (c) 2012, Joyent, Inc. All rights reserved.
27  * Copyright 2013 DEY Storage Systems, Inc.
28  * Copyright 2014 HybridCluster. All rights reserved.
29  */
30 
31 /* Portions Copyright 2010 Robert Milkowski */
32 
33 #ifndef	_SYS_DMU_H
34 #define	_SYS_DMU_H
35 
36 /*
37  * This file describes the interface that the DMU provides for its
38  * consumers.
39  *
40  * The DMU also interacts with the SPA.  That interface is described in
41  * dmu_spa.h.
42  */
43 
44 #include <sys/inttypes.h>
45 #include <sys/types.h>
46 #include <sys/param.h>
47 #include <sys/cred.h>
48 #include <sys/time.h>
49 #include <sys/fs/zfs.h>
50 
51 #ifdef	__cplusplus
52 extern "C" {
53 #endif
54 
55 struct uio;
56 struct xuio;
57 struct page;
58 struct vnode;
59 struct spa;
60 struct zilog;
61 struct zio;
62 struct blkptr;
63 struct zap_cursor;
64 struct dsl_dataset;
65 struct dsl_pool;
66 struct dnode;
67 struct drr_begin;
68 struct drr_end;
69 struct zbookmark_phys;
70 struct spa;
71 struct nvlist;
72 struct arc_buf;
73 struct zio_prop;
74 struct sa_handle;
75 
76 typedef struct objset objset_t;
77 typedef struct dmu_tx dmu_tx_t;
78 typedef struct dsl_dir dsl_dir_t;
79 
80 typedef enum dmu_object_byteswap {
81 	DMU_BSWAP_UINT8,
82 	DMU_BSWAP_UINT16,
83 	DMU_BSWAP_UINT32,
84 	DMU_BSWAP_UINT64,
85 	DMU_BSWAP_ZAP,
86 	DMU_BSWAP_DNODE,
87 	DMU_BSWAP_OBJSET,
88 	DMU_BSWAP_ZNODE,
89 	DMU_BSWAP_OLDACL,
90 	DMU_BSWAP_ACL,
91 	/*
92 	 * Allocating a new byteswap type number makes the on-disk format
93 	 * incompatible with any other format that uses the same number.
94 	 *
95 	 * Data can usually be structured to work with one of the
96 	 * DMU_BSWAP_UINT* or DMU_BSWAP_ZAP types.
97 	 */
98 	DMU_BSWAP_NUMFUNCS
99 } dmu_object_byteswap_t;
100 
101 #define	DMU_OT_NEWTYPE 0x80
102 #define	DMU_OT_METADATA 0x40
103 #define	DMU_OT_BYTESWAP_MASK 0x3f
104 
105 /*
106  * Defines a uint8_t object type. Object types specify if the data
107  * in the object is metadata (boolean) and how to byteswap the data
108  * (dmu_object_byteswap_t).
109  */
110 #define	DMU_OT(byteswap, metadata) \
111 	(DMU_OT_NEWTYPE | \
112 	((metadata) ? DMU_OT_METADATA : 0) | \
113 	((byteswap) & DMU_OT_BYTESWAP_MASK))
114 
115 #define	DMU_OT_IS_VALID(ot) (((ot) & DMU_OT_NEWTYPE) ? \
116 	((ot) & DMU_OT_BYTESWAP_MASK) < DMU_BSWAP_NUMFUNCS : \
117 	(ot) < DMU_OT_NUMTYPES)
118 
119 #define	DMU_OT_IS_METADATA(ot) (((ot) & DMU_OT_NEWTYPE) ? \
120 	((ot) & DMU_OT_METADATA) : \
121 	dmu_ot[(ot)].ot_metadata)
122 
123 /*
124  * These object types use bp_fill != 1 for their L0 bp's. Therefore they can't
125  * have their data embedded (i.e. use a BP_IS_EMBEDDED() bp), because bp_fill
126  * is repurposed for embedded BPs.
127  */
128 #define	DMU_OT_HAS_FILL(ot) \
129 	((ot) == DMU_OT_DNODE || (ot) == DMU_OT_OBJSET)
130 
131 #define	DMU_OT_BYTESWAP(ot) (((ot) & DMU_OT_NEWTYPE) ? \
132 	((ot) & DMU_OT_BYTESWAP_MASK) : \
133 	dmu_ot[(ot)].ot_byteswap)
134 
135 typedef enum dmu_object_type {
136 	DMU_OT_NONE,
137 	/* general: */
138 	DMU_OT_OBJECT_DIRECTORY,	/* ZAP */
139 	DMU_OT_OBJECT_ARRAY,		/* UINT64 */
140 	DMU_OT_PACKED_NVLIST,		/* UINT8 (XDR by nvlist_pack/unpack) */
141 	DMU_OT_PACKED_NVLIST_SIZE,	/* UINT64 */
142 	DMU_OT_BPOBJ,			/* UINT64 */
143 	DMU_OT_BPOBJ_HDR,		/* UINT64 */
144 	/* spa: */
145 	DMU_OT_SPACE_MAP_HEADER,	/* UINT64 */
146 	DMU_OT_SPACE_MAP,		/* UINT64 */
147 	/* zil: */
148 	DMU_OT_INTENT_LOG,		/* UINT64 */
149 	/* dmu: */
150 	DMU_OT_DNODE,			/* DNODE */
151 	DMU_OT_OBJSET,			/* OBJSET */
152 	/* dsl: */
153 	DMU_OT_DSL_DIR,			/* UINT64 */
154 	DMU_OT_DSL_DIR_CHILD_MAP,	/* ZAP */
155 	DMU_OT_DSL_DS_SNAP_MAP,		/* ZAP */
156 	DMU_OT_DSL_PROPS,		/* ZAP */
157 	DMU_OT_DSL_DATASET,		/* UINT64 */
158 	/* zpl: */
159 	DMU_OT_ZNODE,			/* ZNODE */
160 	DMU_OT_OLDACL,			/* Old ACL */
161 	DMU_OT_PLAIN_FILE_CONTENTS,	/* UINT8 */
162 	DMU_OT_DIRECTORY_CONTENTS,	/* ZAP */
163 	DMU_OT_MASTER_NODE,		/* ZAP */
164 	DMU_OT_UNLINKED_SET,		/* ZAP */
165 	/* zvol: */
166 	DMU_OT_ZVOL,			/* UINT8 */
167 	DMU_OT_ZVOL_PROP,		/* ZAP */
168 	/* other; for testing only! */
169 	DMU_OT_PLAIN_OTHER,		/* UINT8 */
170 	DMU_OT_UINT64_OTHER,		/* UINT64 */
171 	DMU_OT_ZAP_OTHER,		/* ZAP */
172 	/* new object types: */
173 	DMU_OT_ERROR_LOG,		/* ZAP */
174 	DMU_OT_SPA_HISTORY,		/* UINT8 */
175 	DMU_OT_SPA_HISTORY_OFFSETS,	/* spa_his_phys_t */
176 	DMU_OT_POOL_PROPS,		/* ZAP */
177 	DMU_OT_DSL_PERMS,		/* ZAP */
178 	DMU_OT_ACL,			/* ACL */
179 	DMU_OT_SYSACL,			/* SYSACL */
180 	DMU_OT_FUID,			/* FUID table (Packed NVLIST UINT8) */
181 	DMU_OT_FUID_SIZE,		/* FUID table size UINT64 */
182 	DMU_OT_NEXT_CLONES,		/* ZAP */
183 	DMU_OT_SCAN_QUEUE,		/* ZAP */
184 	DMU_OT_USERGROUP_USED,		/* ZAP */
185 	DMU_OT_USERGROUP_QUOTA,		/* ZAP */
186 	DMU_OT_USERREFS,		/* ZAP */
187 	DMU_OT_DDT_ZAP,			/* ZAP */
188 	DMU_OT_DDT_STATS,		/* ZAP */
189 	DMU_OT_SA,			/* System attr */
190 	DMU_OT_SA_MASTER_NODE,		/* ZAP */
191 	DMU_OT_SA_ATTR_REGISTRATION,	/* ZAP */
192 	DMU_OT_SA_ATTR_LAYOUTS,		/* ZAP */
193 	DMU_OT_SCAN_XLATE,		/* ZAP */
194 	DMU_OT_DEDUP,			/* fake dedup BP from ddt_bp_create() */
195 	DMU_OT_DEADLIST,		/* ZAP */
196 	DMU_OT_DEADLIST_HDR,		/* UINT64 */
197 	DMU_OT_DSL_CLONES,		/* ZAP */
198 	DMU_OT_BPOBJ_SUBOBJ,		/* UINT64 */
199 	/*
200 	 * Do not allocate new object types here. Doing so makes the on-disk
201 	 * format incompatible with any other format that uses the same object
202 	 * type number.
203 	 *
204 	 * When creating an object which does not have one of the above types
205 	 * use the DMU_OTN_* type with the correct byteswap and metadata
206 	 * values.
207 	 *
208 	 * The DMU_OTN_* types do not have entries in the dmu_ot table,
209 	 * use the DMU_OT_IS_METDATA() and DMU_OT_BYTESWAP() macros instead
210 	 * of indexing into dmu_ot directly (this works for both DMU_OT_* types
211 	 * and DMU_OTN_* types).
212 	 */
213 	DMU_OT_NUMTYPES,
214 
215 	/*
216 	 * Names for valid types declared with DMU_OT().
217 	 */
218 	DMU_OTN_UINT8_DATA = DMU_OT(DMU_BSWAP_UINT8, B_FALSE),
219 	DMU_OTN_UINT8_METADATA = DMU_OT(DMU_BSWAP_UINT8, B_TRUE),
220 	DMU_OTN_UINT16_DATA = DMU_OT(DMU_BSWAP_UINT16, B_FALSE),
221 	DMU_OTN_UINT16_METADATA = DMU_OT(DMU_BSWAP_UINT16, B_TRUE),
222 	DMU_OTN_UINT32_DATA = DMU_OT(DMU_BSWAP_UINT32, B_FALSE),
223 	DMU_OTN_UINT32_METADATA = DMU_OT(DMU_BSWAP_UINT32, B_TRUE),
224 	DMU_OTN_UINT64_DATA = DMU_OT(DMU_BSWAP_UINT64, B_FALSE),
225 	DMU_OTN_UINT64_METADATA = DMU_OT(DMU_BSWAP_UINT64, B_TRUE),
226 	DMU_OTN_ZAP_DATA = DMU_OT(DMU_BSWAP_ZAP, B_FALSE),
227 	DMU_OTN_ZAP_METADATA = DMU_OT(DMU_BSWAP_ZAP, B_TRUE),
228 } dmu_object_type_t;
229 
230 typedef enum txg_how {
231 	TXG_WAIT = 1,
232 	TXG_NOWAIT,
233 	TXG_WAITED,
234 } txg_how_t;
235 
236 void byteswap_uint64_array(void *buf, size_t size);
237 void byteswap_uint32_array(void *buf, size_t size);
238 void byteswap_uint16_array(void *buf, size_t size);
239 void byteswap_uint8_array(void *buf, size_t size);
240 void zap_byteswap(void *buf, size_t size);
241 void zfs_oldacl_byteswap(void *buf, size_t size);
242 void zfs_acl_byteswap(void *buf, size_t size);
243 void zfs_znode_byteswap(void *buf, size_t size);
244 
245 #define	DS_FIND_SNAPSHOTS	(1<<0)
246 #define	DS_FIND_CHILDREN	(1<<1)
247 
248 /*
249  * The maximum number of bytes that can be accessed as part of one
250  * operation, including metadata.
251  */
252 #define	DMU_MAX_ACCESS (32 * 1024 * 1024) /* 32MB */
253 #define	DMU_MAX_DELETEBLKCNT (20480) /* ~5MB of indirect blocks */
254 
255 #define	DMU_USERUSED_OBJECT	(-1ULL)
256 #define	DMU_GROUPUSED_OBJECT	(-2ULL)
257 
258 /*
259  * artificial blkids for bonus buffer and spill blocks
260  */
261 #define	DMU_BONUS_BLKID		(-1ULL)
262 #define	DMU_SPILL_BLKID		(-2ULL)
263 /*
264  * Public routines to create, destroy, open, and close objsets.
265  */
266 int dmu_objset_hold(const char *name, void *tag, objset_t **osp);
267 int dmu_objset_own(const char *name, dmu_objset_type_t type,
268     boolean_t readonly, void *tag, objset_t **osp);
269 void dmu_objset_rele(objset_t *os, void *tag);
270 void dmu_objset_disown(objset_t *os, void *tag);
271 int dmu_objset_open_ds(struct dsl_dataset *ds, objset_t **osp);
272 
273 void dmu_objset_evict_dbufs(objset_t *os);
274 int dmu_objset_create(const char *name, dmu_objset_type_t type, uint64_t flags,
275     void (*func)(objset_t *os, void *arg, cred_t *cr, dmu_tx_t *tx), void *arg);
276 int dmu_objset_clone(const char *name, const char *origin);
277 int dsl_destroy_snapshots_nvl(struct nvlist *snaps, boolean_t defer,
278     struct nvlist *errlist);
279 int dmu_objset_snapshot_one(const char *fsname, const char *snapname);
280 int dmu_objset_snapshot_tmp(const char *, const char *, int);
281 int dmu_objset_find(char *name, int func(const char *, void *), void *arg,
282     int flags);
283 void dmu_objset_byteswap(void *buf, size_t size);
284 int dsl_dataset_rename_snapshot(const char *fsname,
285     const char *oldsnapname, const char *newsnapname, boolean_t recursive);
286 
287 typedef struct dmu_buf {
288 	uint64_t db_object;		/* object that this buffer is part of */
289 	uint64_t db_offset;		/* byte offset in this object */
290 	uint64_t db_size;		/* size of buffer in bytes */
291 	void *db_data;			/* data in buffer */
292 } dmu_buf_t;
293 
294 typedef void dmu_buf_evict_func_t(struct dmu_buf *db, void *user_ptr);
295 
296 /*
297  * The names of zap entries in the DIRECTORY_OBJECT of the MOS.
298  */
299 #define	DMU_POOL_DIRECTORY_OBJECT	1
300 #define	DMU_POOL_CONFIG			"config"
301 #define	DMU_POOL_FEATURES_FOR_WRITE	"features_for_write"
302 #define	DMU_POOL_FEATURES_FOR_READ	"features_for_read"
303 #define	DMU_POOL_FEATURE_DESCRIPTIONS	"feature_descriptions"
304 #define	DMU_POOL_FEATURE_ENABLED_TXG	"feature_enabled_txg"
305 #define	DMU_POOL_ROOT_DATASET		"root_dataset"
306 #define	DMU_POOL_SYNC_BPOBJ		"sync_bplist"
307 #define	DMU_POOL_ERRLOG_SCRUB		"errlog_scrub"
308 #define	DMU_POOL_ERRLOG_LAST		"errlog_last"
309 #define	DMU_POOL_SPARES			"spares"
310 #define	DMU_POOL_DEFLATE		"deflate"
311 #define	DMU_POOL_HISTORY		"history"
312 #define	DMU_POOL_PROPS			"pool_props"
313 #define	DMU_POOL_L2CACHE		"l2cache"
314 #define	DMU_POOL_TMP_USERREFS		"tmp_userrefs"
315 #define	DMU_POOL_DDT			"DDT-%s-%s-%s"
316 #define	DMU_POOL_DDT_STATS		"DDT-statistics"
317 #define	DMU_POOL_CREATION_VERSION	"creation_version"
318 #define	DMU_POOL_SCAN			"scan"
319 #define	DMU_POOL_FREE_BPOBJ		"free_bpobj"
320 #define	DMU_POOL_BPTREE_OBJ		"bptree_obj"
321 #define	DMU_POOL_EMPTY_BPOBJ		"empty_bpobj"
322 
323 /*
324  * Allocate an object from this objset.  The range of object numbers
325  * available is (0, DN_MAX_OBJECT).  Object 0 is the meta-dnode.
326  *
327  * The transaction must be assigned to a txg.  The newly allocated
328  * object will be "held" in the transaction (ie. you can modify the
329  * newly allocated object in this transaction).
330  *
331  * dmu_object_alloc() chooses an object and returns it in *objectp.
332  *
333  * dmu_object_claim() allocates a specific object number.  If that
334  * number is already allocated, it fails and returns EEXIST.
335  *
336  * Return 0 on success, or ENOSPC or EEXIST as specified above.
337  */
338 uint64_t dmu_object_alloc(objset_t *os, dmu_object_type_t ot,
339     int blocksize, dmu_object_type_t bonus_type, int bonus_len, dmu_tx_t *tx);
340 int dmu_object_claim(objset_t *os, uint64_t object, dmu_object_type_t ot,
341     int blocksize, dmu_object_type_t bonus_type, int bonus_len, dmu_tx_t *tx);
342 int dmu_object_reclaim(objset_t *os, uint64_t object, dmu_object_type_t ot,
343     int blocksize, dmu_object_type_t bonustype, int bonuslen, dmu_tx_t *txp);
344 
345 /*
346  * Free an object from this objset.
347  *
348  * The object's data will be freed as well (ie. you don't need to call
349  * dmu_free(object, 0, -1, tx)).
350  *
351  * The object need not be held in the transaction.
352  *
353  * If there are any holds on this object's buffers (via dmu_buf_hold()),
354  * or tx holds on the object (via dmu_tx_hold_object()), you can not
355  * free it; it fails and returns EBUSY.
356  *
357  * If the object is not allocated, it fails and returns ENOENT.
358  *
359  * Return 0 on success, or EBUSY or ENOENT as specified above.
360  */
361 int dmu_object_free(objset_t *os, uint64_t object, dmu_tx_t *tx);
362 
363 /*
364  * Find the next allocated or free object.
365  *
366  * The objectp parameter is in-out.  It will be updated to be the next
367  * object which is allocated.  Ignore objects which have not been
368  * modified since txg.
369  *
370  * XXX Can only be called on a objset with no dirty data.
371  *
372  * Returns 0 on success, or ENOENT if there are no more objects.
373  */
374 int dmu_object_next(objset_t *os, uint64_t *objectp,
375     boolean_t hole, uint64_t txg);
376 
377 /*
378  * Set the data blocksize for an object.
379  *
380  * The object cannot have any blocks allcated beyond the first.  If
381  * the first block is allocated already, the new size must be greater
382  * than the current block size.  If these conditions are not met,
383  * ENOTSUP will be returned.
384  *
385  * Returns 0 on success, or EBUSY if there are any holds on the object
386  * contents, or ENOTSUP as described above.
387  */
388 int dmu_object_set_blocksize(objset_t *os, uint64_t object, uint64_t size,
389     int ibs, dmu_tx_t *tx);
390 
391 /*
392  * Set the checksum property on a dnode.  The new checksum algorithm will
393  * apply to all newly written blocks; existing blocks will not be affected.
394  */
395 void dmu_object_set_checksum(objset_t *os, uint64_t object, uint8_t checksum,
396     dmu_tx_t *tx);
397 
398 /*
399  * Set the compress property on a dnode.  The new compression algorithm will
400  * apply to all newly written blocks; existing blocks will not be affected.
401  */
402 void dmu_object_set_compress(objset_t *os, uint64_t object, uint8_t compress,
403     dmu_tx_t *tx);
404 
405 void
406 dmu_write_embedded(objset_t *os, uint64_t object, uint64_t offset,
407     void *data, uint8_t etype, uint8_t comp, int uncompressed_size,
408     int compressed_size, int byteorder, dmu_tx_t *tx);
409 
410 /*
411  * Decide how to write a block: checksum, compression, number of copies, etc.
412  */
413 #define	WP_NOFILL	0x1
414 #define	WP_DMU_SYNC	0x2
415 #define	WP_SPILL	0x4
416 
417 void dmu_write_policy(objset_t *os, struct dnode *dn, int level, int wp,
418     struct zio_prop *zp);
419 /*
420  * The bonus data is accessed more or less like a regular buffer.
421  * You must dmu_bonus_hold() to get the buffer, which will give you a
422  * dmu_buf_t with db_offset==-1ULL, and db_size = the size of the bonus
423  * data.  As with any normal buffer, you must call dmu_buf_read() to
424  * read db_data, dmu_buf_will_dirty() before modifying it, and the
425  * object must be held in an assigned transaction before calling
426  * dmu_buf_will_dirty.  You may use dmu_buf_set_user() on the bonus
427  * buffer as well.  You must release your hold with dmu_buf_rele().
428  *
429  * Returns ENOENT, EIO, or 0.
430  */
431 int dmu_bonus_hold(objset_t *os, uint64_t object, void *tag, dmu_buf_t **);
432 int dmu_bonus_max(void);
433 int dmu_set_bonus(dmu_buf_t *, int, dmu_tx_t *);
434 int dmu_set_bonustype(dmu_buf_t *, dmu_object_type_t, dmu_tx_t *);
435 dmu_object_type_t dmu_get_bonustype(dmu_buf_t *);
436 int dmu_rm_spill(objset_t *, uint64_t, dmu_tx_t *);
437 
438 /*
439  * Special spill buffer support used by "SA" framework
440  */
441 
442 int dmu_spill_hold_by_bonus(dmu_buf_t *bonus, void *tag, dmu_buf_t **dbp);
443 int dmu_spill_hold_by_dnode(struct dnode *dn, uint32_t flags,
444     void *tag, dmu_buf_t **dbp);
445 int dmu_spill_hold_existing(dmu_buf_t *bonus, void *tag, dmu_buf_t **dbp);
446 
447 /*
448  * Obtain the DMU buffer from the specified object which contains the
449  * specified offset.  dmu_buf_hold() puts a "hold" on the buffer, so
450  * that it will remain in memory.  You must release the hold with
451  * dmu_buf_rele().  You musn't access the dmu_buf_t after releasing your
452  * hold.  You must have a hold on any dmu_buf_t* you pass to the DMU.
453  *
454  * You must call dmu_buf_read, dmu_buf_will_dirty, or dmu_buf_will_fill
455  * on the returned buffer before reading or writing the buffer's
456  * db_data.  The comments for those routines describe what particular
457  * operations are valid after calling them.
458  *
459  * The object number must be a valid, allocated object number.
460  */
461 int dmu_buf_hold(objset_t *os, uint64_t object, uint64_t offset,
462     void *tag, dmu_buf_t **, int flags);
463 void dmu_buf_add_ref(dmu_buf_t *db, void* tag);
464 void dmu_buf_rele(dmu_buf_t *db, void *tag);
465 uint64_t dmu_buf_refcount(dmu_buf_t *db);
466 
467 /*
468  * dmu_buf_hold_array holds the DMU buffers which contain all bytes in a
469  * range of an object.  A pointer to an array of dmu_buf_t*'s is
470  * returned (in *dbpp).
471  *
472  * dmu_buf_rele_array releases the hold on an array of dmu_buf_t*'s, and
473  * frees the array.  The hold on the array of buffers MUST be released
474  * with dmu_buf_rele_array.  You can NOT release the hold on each buffer
475  * individually with dmu_buf_rele.
476  */
477 int dmu_buf_hold_array_by_bonus(dmu_buf_t *db, uint64_t offset,
478     uint64_t length, int read, void *tag, int *numbufsp, dmu_buf_t ***dbpp);
479 void dmu_buf_rele_array(dmu_buf_t **, int numbufs, void *tag);
480 
481 /*
482  * Returns NULL on success, or the existing user ptr if it's already
483  * been set.
484  *
485  * user_ptr is for use by the user and can be obtained via dmu_buf_get_user().
486  *
487  * user_data_ptr_ptr should be NULL, or a pointer to a pointer which
488  * will be set to db->db_data when you are allowed to access it.  Note
489  * that db->db_data (the pointer) can change when you do dmu_buf_read(),
490  * dmu_buf_tryupgrade(), dmu_buf_will_dirty(), or dmu_buf_will_fill().
491  * *user_data_ptr_ptr will be set to the new value when it changes.
492  *
493  * If non-NULL, pageout func will be called when this buffer is being
494  * excised from the cache, so that you can clean up the data structure
495  * pointed to by user_ptr.
496  *
497  * dmu_evict_user() will call the pageout func for all buffers in a
498  * objset with a given pageout func.
499  */
500 void *dmu_buf_set_user(dmu_buf_t *db, void *user_ptr, void *user_data_ptr_ptr,
501     dmu_buf_evict_func_t *pageout_func);
502 /*
503  * set_user_ie is the same as set_user, but request immediate eviction
504  * when hold count goes to zero.
505  */
506 void *dmu_buf_set_user_ie(dmu_buf_t *db, void *user_ptr,
507     void *user_data_ptr_ptr, dmu_buf_evict_func_t *pageout_func);
508 void *dmu_buf_update_user(dmu_buf_t *db_fake, void *old_user_ptr,
509     void *user_ptr, void *user_data_ptr_ptr,
510     dmu_buf_evict_func_t *pageout_func);
511 void dmu_evict_user(objset_t *os, dmu_buf_evict_func_t *func);
512 
513 /*
514  * Returns the user_ptr set with dmu_buf_set_user(), or NULL if not set.
515  */
516 void *dmu_buf_get_user(dmu_buf_t *db);
517 
518 /*
519  * Returns the blkptr associated with this dbuf, or NULL if not set.
520  */
521 struct blkptr *dmu_buf_get_blkptr(dmu_buf_t *db);
522 
523 /*
524  * Indicate that you are going to modify the buffer's data (db_data).
525  *
526  * The transaction (tx) must be assigned to a txg (ie. you've called
527  * dmu_tx_assign()).  The buffer's object must be held in the tx
528  * (ie. you've called dmu_tx_hold_object(tx, db->db_object)).
529  */
530 void dmu_buf_will_dirty(dmu_buf_t *db, dmu_tx_t *tx);
531 
532 /*
533  * Tells if the given dbuf is freeable.
534  */
535 boolean_t dmu_buf_freeable(dmu_buf_t *);
536 
537 /*
538  * You must create a transaction, then hold the objects which you will
539  * (or might) modify as part of this transaction.  Then you must assign
540  * the transaction to a transaction group.  Once the transaction has
541  * been assigned, you can modify buffers which belong to held objects as
542  * part of this transaction.  You can't modify buffers before the
543  * transaction has been assigned; you can't modify buffers which don't
544  * belong to objects which this transaction holds; you can't hold
545  * objects once the transaction has been assigned.  You may hold an
546  * object which you are going to free (with dmu_object_free()), but you
547  * don't have to.
548  *
549  * You can abort the transaction before it has been assigned.
550  *
551  * Note that you may hold buffers (with dmu_buf_hold) at any time,
552  * regardless of transaction state.
553  */
554 
555 #define	DMU_NEW_OBJECT	(-1ULL)
556 #define	DMU_OBJECT_END	(-1ULL)
557 
558 dmu_tx_t *dmu_tx_create(objset_t *os);
559 void dmu_tx_hold_write(dmu_tx_t *tx, uint64_t object, uint64_t off, int len);
560 void dmu_tx_hold_free(dmu_tx_t *tx, uint64_t object, uint64_t off,
561     uint64_t len);
562 void dmu_tx_hold_zap(dmu_tx_t *tx, uint64_t object, int add, const char *name);
563 void dmu_tx_hold_bonus(dmu_tx_t *tx, uint64_t object);
564 void dmu_tx_hold_spill(dmu_tx_t *tx, uint64_t object);
565 void dmu_tx_hold_sa(dmu_tx_t *tx, struct sa_handle *hdl, boolean_t may_grow);
566 void dmu_tx_hold_sa_create(dmu_tx_t *tx, int total_size);
567 void dmu_tx_abort(dmu_tx_t *tx);
568 int dmu_tx_assign(dmu_tx_t *tx, enum txg_how txg_how);
569 void dmu_tx_wait(dmu_tx_t *tx);
570 void dmu_tx_commit(dmu_tx_t *tx);
571 void dmu_tx_mark_netfree(dmu_tx_t *tx);
572 
573 /*
574  * To register a commit callback, dmu_tx_callback_register() must be called.
575  *
576  * dcb_data is a pointer to caller private data that is passed on as a
577  * callback parameter. The caller is responsible for properly allocating and
578  * freeing it.
579  *
580  * When registering a callback, the transaction must be already created, but
581  * it cannot be committed or aborted. It can be assigned to a txg or not.
582  *
583  * The callback will be called after the transaction has been safely written
584  * to stable storage and will also be called if the dmu_tx is aborted.
585  * If there is any error which prevents the transaction from being committed to
586  * disk, the callback will be called with a value of error != 0.
587  */
588 typedef void dmu_tx_callback_func_t(void *dcb_data, int error);
589 
590 void dmu_tx_callback_register(dmu_tx_t *tx, dmu_tx_callback_func_t *dcb_func,
591     void *dcb_data);
592 
593 /*
594  * Free up the data blocks for a defined range of a file.  If size is
595  * -1, the range from offset to end-of-file is freed.
596  */
597 int dmu_free_range(objset_t *os, uint64_t object, uint64_t offset,
598 	uint64_t size, dmu_tx_t *tx);
599 int dmu_free_long_range(objset_t *os, uint64_t object, uint64_t offset,
600 	uint64_t size);
601 int dmu_free_long_object(objset_t *os, uint64_t object);
602 
603 /*
604  * Convenience functions.
605  *
606  * Canfail routines will return 0 on success, or an errno if there is a
607  * nonrecoverable I/O error.
608  */
609 #define	DMU_READ_PREFETCH	0 /* prefetch */
610 #define	DMU_READ_NO_PREFETCH	1 /* don't prefetch */
611 int dmu_read(objset_t *os, uint64_t object, uint64_t offset, uint64_t size,
612 	void *buf, uint32_t flags);
613 void dmu_write(objset_t *os, uint64_t object, uint64_t offset, uint64_t size,
614 	const void *buf, dmu_tx_t *tx);
615 void dmu_prealloc(objset_t *os, uint64_t object, uint64_t offset, uint64_t size,
616 	dmu_tx_t *tx);
617 int dmu_read_uio(objset_t *os, uint64_t object, struct uio *uio, uint64_t size);
618 int dmu_read_uio_dbuf(dmu_buf_t *zdb, struct uio *uio, uint64_t size);
619 int dmu_write_uio(objset_t *os, uint64_t object, struct uio *uio, uint64_t size,
620     dmu_tx_t *tx);
621 int dmu_write_uio_dbuf(dmu_buf_t *zdb, struct uio *uio, uint64_t size,
622     dmu_tx_t *tx);
623 int dmu_write_pages(objset_t *os, uint64_t object, uint64_t offset,
624     uint64_t size, struct page *pp, dmu_tx_t *tx);
625 struct arc_buf *dmu_request_arcbuf(dmu_buf_t *handle, int size);
626 void dmu_return_arcbuf(struct arc_buf *buf);
627 void dmu_assign_arcbuf(dmu_buf_t *handle, uint64_t offset, struct arc_buf *buf,
628     dmu_tx_t *tx);
629 int dmu_xuio_init(struct xuio *uio, int niov);
630 void dmu_xuio_fini(struct xuio *uio);
631 int dmu_xuio_add(struct xuio *uio, struct arc_buf *abuf, offset_t off,
632     size_t n);
633 int dmu_xuio_cnt(struct xuio *uio);
634 struct arc_buf *dmu_xuio_arcbuf(struct xuio *uio, int i);
635 void dmu_xuio_clear(struct xuio *uio, int i);
636 void xuio_stat_wbuf_copied();
637 void xuio_stat_wbuf_nocopy();
638 
639 extern int zfs_prefetch_disable;
640 extern int zfs_max_recordsize;
641 
642 /*
643  * Asynchronously try to read in the data.
644  */
645 void dmu_prefetch(objset_t *os, uint64_t object, uint64_t offset,
646     uint64_t len);
647 
648 typedef struct dmu_object_info {
649 	/* All sizes are in bytes unless otherwise indicated. */
650 	uint32_t doi_data_block_size;
651 	uint32_t doi_metadata_block_size;
652 	dmu_object_type_t doi_type;
653 	dmu_object_type_t doi_bonus_type;
654 	uint64_t doi_bonus_size;
655 	uint8_t doi_indirection;		/* 2 = dnode->indirect->data */
656 	uint8_t doi_checksum;
657 	uint8_t doi_compress;
658 	uint8_t doi_nblkptr;
659 	uint8_t doi_pad[4];
660 	uint64_t doi_physical_blocks_512;	/* data + metadata, 512b blks */
661 	uint64_t doi_max_offset;
662 	uint64_t doi_fill_count;		/* number of non-empty blocks */
663 } dmu_object_info_t;
664 
665 typedef void arc_byteswap_func_t(void *buf, size_t size);
666 
667 typedef struct dmu_object_type_info {
668 	dmu_object_byteswap_t	ot_byteswap;
669 	boolean_t		ot_metadata;
670 	char			*ot_name;
671 } dmu_object_type_info_t;
672 
673 typedef struct dmu_object_byteswap_info {
674 	arc_byteswap_func_t	*ob_func;
675 	char			*ob_name;
676 } dmu_object_byteswap_info_t;
677 
678 extern const dmu_object_type_info_t dmu_ot[DMU_OT_NUMTYPES];
679 extern const dmu_object_byteswap_info_t dmu_ot_byteswap[DMU_BSWAP_NUMFUNCS];
680 
681 /*
682  * Get information on a DMU object.
683  *
684  * Return 0 on success or ENOENT if object is not allocated.
685  *
686  * If doi is NULL, just indicates whether the object exists.
687  */
688 int dmu_object_info(objset_t *os, uint64_t object, dmu_object_info_t *doi);
689 /* Like dmu_object_info, but faster if you have a held dnode in hand. */
690 void dmu_object_info_from_dnode(struct dnode *dn, dmu_object_info_t *doi);
691 /* Like dmu_object_info, but faster if you have a held dbuf in hand. */
692 void dmu_object_info_from_db(dmu_buf_t *db, dmu_object_info_t *doi);
693 /*
694  * Like dmu_object_info_from_db, but faster still when you only care about
695  * the size.  This is specifically optimized for zfs_getattr().
696  */
697 void dmu_object_size_from_db(dmu_buf_t *db, uint32_t *blksize,
698     u_longlong_t *nblk512);
699 
700 typedef struct dmu_objset_stats {
701 	uint64_t dds_num_clones; /* number of clones of this */
702 	uint64_t dds_creation_txg;
703 	uint64_t dds_guid;
704 	dmu_objset_type_t dds_type;
705 	uint8_t dds_is_snapshot;
706 	uint8_t dds_inconsistent;
707 	char dds_origin[MAXNAMELEN];
708 } dmu_objset_stats_t;
709 
710 /*
711  * Get stats on a dataset.
712  */
713 void dmu_objset_fast_stat(objset_t *os, dmu_objset_stats_t *stat);
714 
715 /*
716  * Add entries to the nvlist for all the objset's properties.  See
717  * zfs_prop_table[] and zfs(1m) for details on the properties.
718  */
719 void dmu_objset_stats(objset_t *os, struct nvlist *nv);
720 
721 /*
722  * Get the space usage statistics for statvfs().
723  *
724  * refdbytes is the amount of space "referenced" by this objset.
725  * availbytes is the amount of space available to this objset, taking
726  * into account quotas & reservations, assuming that no other objsets
727  * use the space first.  These values correspond to the 'referenced' and
728  * 'available' properties, described in the zfs(1m) manpage.
729  *
730  * usedobjs and availobjs are the number of objects currently allocated,
731  * and available.
732  */
733 void dmu_objset_space(objset_t *os, uint64_t *refdbytesp, uint64_t *availbytesp,
734     uint64_t *usedobjsp, uint64_t *availobjsp);
735 
736 /*
737  * The fsid_guid is a 56-bit ID that can change to avoid collisions.
738  * (Contrast with the ds_guid which is a 64-bit ID that will never
739  * change, so there is a small probability that it will collide.)
740  */
741 uint64_t dmu_objset_fsid_guid(objset_t *os);
742 
743 /*
744  * Get the [cm]time for an objset's snapshot dir
745  */
746 timestruc_t dmu_objset_snap_cmtime(objset_t *os);
747 
748 int dmu_objset_is_snapshot(objset_t *os);
749 
750 extern struct spa *dmu_objset_spa(objset_t *os);
751 extern struct zilog *dmu_objset_zil(objset_t *os);
752 extern struct dsl_pool *dmu_objset_pool(objset_t *os);
753 extern struct dsl_dataset *dmu_objset_ds(objset_t *os);
754 extern void dmu_objset_name(objset_t *os, char *buf);
755 extern dmu_objset_type_t dmu_objset_type(objset_t *os);
756 extern uint64_t dmu_objset_id(objset_t *os);
757 extern zfs_sync_type_t dmu_objset_syncprop(objset_t *os);
758 extern zfs_logbias_op_t dmu_objset_logbias(objset_t *os);
759 extern int dmu_snapshot_list_next(objset_t *os, int namelen, char *name,
760     uint64_t *id, uint64_t *offp, boolean_t *case_conflict);
761 extern int dmu_snapshot_realname(objset_t *os, char *name, char *real,
762     int maxlen, boolean_t *conflict);
763 extern int dmu_dir_list_next(objset_t *os, int namelen, char *name,
764     uint64_t *idp, uint64_t *offp);
765 
766 typedef int objset_used_cb_t(dmu_object_type_t bonustype,
767     void *bonus, uint64_t *userp, uint64_t *groupp);
768 extern void dmu_objset_register_type(dmu_objset_type_t ost,
769     objset_used_cb_t *cb);
770 extern void dmu_objset_set_user(objset_t *os, void *user_ptr);
771 extern void *dmu_objset_get_user(objset_t *os);
772 
773 /*
774  * Return the txg number for the given assigned transaction.
775  */
776 uint64_t dmu_tx_get_txg(dmu_tx_t *tx);
777 
778 /*
779  * Synchronous write.
780  * If a parent zio is provided this function initiates a write on the
781  * provided buffer as a child of the parent zio.
782  * In the absence of a parent zio, the write is completed synchronously.
783  * At write completion, blk is filled with the bp of the written block.
784  * Note that while the data covered by this function will be on stable
785  * storage when the write completes this new data does not become a
786  * permanent part of the file until the associated transaction commits.
787  */
788 
789 /*
790  * {zfs,zvol,ztest}_get_done() args
791  */
792 typedef struct zgd {
793 	struct zilog	*zgd_zilog;
794 	struct blkptr	*zgd_bp;
795 	dmu_buf_t	*zgd_db;
796 	struct rl	*zgd_rl;
797 	void		*zgd_private;
798 } zgd_t;
799 
800 typedef void dmu_sync_cb_t(zgd_t *arg, int error);
801 int dmu_sync(struct zio *zio, uint64_t txg, dmu_sync_cb_t *done, zgd_t *zgd);
802 
803 /*
804  * Find the next hole or data block in file starting at *off
805  * Return found offset in *off. Return ESRCH for end of file.
806  */
807 int dmu_offset_next(objset_t *os, uint64_t object, boolean_t hole,
808     uint64_t *off);
809 
810 /*
811  * Initial setup and final teardown.
812  */
813 extern void dmu_init(void);
814 extern void dmu_fini(void);
815 
816 typedef void (*dmu_traverse_cb_t)(objset_t *os, void *arg, struct blkptr *bp,
817     uint64_t object, uint64_t offset, int len);
818 void dmu_traverse_objset(objset_t *os, uint64_t txg_start,
819     dmu_traverse_cb_t cb, void *arg);
820 
821 int dmu_diff(const char *tosnap_name, const char *fromsnap_name,
822     struct vnode *vp, offset_t *offp);
823 
824 /* CRC64 table */
825 #define	ZFS_CRC64_POLY	0xC96C5795D7870F42ULL	/* ECMA-182, reflected form */
826 extern uint64_t zfs_crc64_table[256];
827 
828 extern int zfs_mdcomp_disable;
829 
830 #ifdef	__cplusplus
831 }
832 #endif
833 
834 #endif	/* _SYS_DMU_H */
835