xref: /titanic_52/usr/src/uts/common/fs/zfs/sys/dmu.h (revision 5cb0d67909d9970a3e7adbea9422ca3fc88000bf)
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  */
29 
30 /* Portions Copyright 2010 Robert Milkowski */
31 
32 #ifndef	_SYS_DMU_H
33 #define	_SYS_DMU_H
34 
35 /*
36  * This file describes the interface that the DMU provides for its
37  * consumers.
38  *
39  * The DMU also interacts with the SPA.  That interface is described in
40  * dmu_spa.h.
41  */
42 
43 #include <sys/inttypes.h>
44 #include <sys/types.h>
45 #include <sys/param.h>
46 #include <sys/cred.h>
47 #include <sys/time.h>
48 #include <sys/fs/zfs.h>
49 
50 #ifdef	__cplusplus
51 extern "C" {
52 #endif
53 
54 struct uio;
55 struct xuio;
56 struct page;
57 struct vnode;
58 struct spa;
59 struct zilog;
60 struct zio;
61 struct blkptr;
62 struct zap_cursor;
63 struct dsl_dataset;
64 struct dsl_pool;
65 struct dnode;
66 struct drr_begin;
67 struct drr_end;
68 struct zbookmark_phys;
69 struct spa;
70 struct nvlist;
71 struct arc_buf;
72 struct zio_prop;
73 struct sa_handle;
74 
75 typedef struct objset objset_t;
76 typedef struct dmu_tx dmu_tx_t;
77 typedef struct dsl_dir dsl_dir_t;
78 
79 typedef enum dmu_object_byteswap {
80 	DMU_BSWAP_UINT8,
81 	DMU_BSWAP_UINT16,
82 	DMU_BSWAP_UINT32,
83 	DMU_BSWAP_UINT64,
84 	DMU_BSWAP_ZAP,
85 	DMU_BSWAP_DNODE,
86 	DMU_BSWAP_OBJSET,
87 	DMU_BSWAP_ZNODE,
88 	DMU_BSWAP_OLDACL,
89 	DMU_BSWAP_ACL,
90 	/*
91 	 * Allocating a new byteswap type number makes the on-disk format
92 	 * incompatible with any other format that uses the same number.
93 	 *
94 	 * Data can usually be structured to work with one of the
95 	 * DMU_BSWAP_UINT* or DMU_BSWAP_ZAP types.
96 	 */
97 	DMU_BSWAP_NUMFUNCS
98 } dmu_object_byteswap_t;
99 
100 #define	DMU_OT_NEWTYPE 0x80
101 #define	DMU_OT_METADATA 0x40
102 #define	DMU_OT_BYTESWAP_MASK 0x3f
103 
104 /*
105  * Defines a uint8_t object type. Object types specify if the data
106  * in the object is metadata (boolean) and how to byteswap the data
107  * (dmu_object_byteswap_t).
108  */
109 #define	DMU_OT(byteswap, metadata) \
110 	(DMU_OT_NEWTYPE | \
111 	((metadata) ? DMU_OT_METADATA : 0) | \
112 	((byteswap) & DMU_OT_BYTESWAP_MASK))
113 
114 #define	DMU_OT_IS_VALID(ot) (((ot) & DMU_OT_NEWTYPE) ? \
115 	((ot) & DMU_OT_BYTESWAP_MASK) < DMU_BSWAP_NUMFUNCS : \
116 	(ot) < DMU_OT_NUMTYPES)
117 
118 #define	DMU_OT_IS_METADATA(ot) (((ot) & DMU_OT_NEWTYPE) ? \
119 	((ot) & DMU_OT_METADATA) : \
120 	dmu_ot[(ot)].ot_metadata)
121 
122 /*
123  * These object types use bp_fill != 1 for their L0 bp's. Therefore they can't
124  * have their data embedded (i.e. use a BP_IS_EMBEDDED() bp), because bp_fill
125  * is repurposed for embedded BPs.
126  */
127 #define	DMU_OT_HAS_FILL(ot) \
128 	((ot) == DMU_OT_DNODE || (ot) == DMU_OT_OBJSET)
129 
130 #define	DMU_OT_BYTESWAP(ot) (((ot) & DMU_OT_NEWTYPE) ? \
131 	((ot) & DMU_OT_BYTESWAP_MASK) : \
132 	dmu_ot[(ot)].ot_byteswap)
133 
134 typedef enum dmu_object_type {
135 	DMU_OT_NONE,
136 	/* general: */
137 	DMU_OT_OBJECT_DIRECTORY,	/* ZAP */
138 	DMU_OT_OBJECT_ARRAY,		/* UINT64 */
139 	DMU_OT_PACKED_NVLIST,		/* UINT8 (XDR by nvlist_pack/unpack) */
140 	DMU_OT_PACKED_NVLIST_SIZE,	/* UINT64 */
141 	DMU_OT_BPOBJ,			/* UINT64 */
142 	DMU_OT_BPOBJ_HDR,		/* UINT64 */
143 	/* spa: */
144 	DMU_OT_SPACE_MAP_HEADER,	/* UINT64 */
145 	DMU_OT_SPACE_MAP,		/* UINT64 */
146 	/* zil: */
147 	DMU_OT_INTENT_LOG,		/* UINT64 */
148 	/* dmu: */
149 	DMU_OT_DNODE,			/* DNODE */
150 	DMU_OT_OBJSET,			/* OBJSET */
151 	/* dsl: */
152 	DMU_OT_DSL_DIR,			/* UINT64 */
153 	DMU_OT_DSL_DIR_CHILD_MAP,	/* ZAP */
154 	DMU_OT_DSL_DS_SNAP_MAP,		/* ZAP */
155 	DMU_OT_DSL_PROPS,		/* ZAP */
156 	DMU_OT_DSL_DATASET,		/* UINT64 */
157 	/* zpl: */
158 	DMU_OT_ZNODE,			/* ZNODE */
159 	DMU_OT_OLDACL,			/* Old ACL */
160 	DMU_OT_PLAIN_FILE_CONTENTS,	/* UINT8 */
161 	DMU_OT_DIRECTORY_CONTENTS,	/* ZAP */
162 	DMU_OT_MASTER_NODE,		/* ZAP */
163 	DMU_OT_UNLINKED_SET,		/* ZAP */
164 	/* zvol: */
165 	DMU_OT_ZVOL,			/* UINT8 */
166 	DMU_OT_ZVOL_PROP,		/* ZAP */
167 	/* other; for testing only! */
168 	DMU_OT_PLAIN_OTHER,		/* UINT8 */
169 	DMU_OT_UINT64_OTHER,		/* UINT64 */
170 	DMU_OT_ZAP_OTHER,		/* ZAP */
171 	/* new object types: */
172 	DMU_OT_ERROR_LOG,		/* ZAP */
173 	DMU_OT_SPA_HISTORY,		/* UINT8 */
174 	DMU_OT_SPA_HISTORY_OFFSETS,	/* spa_his_phys_t */
175 	DMU_OT_POOL_PROPS,		/* ZAP */
176 	DMU_OT_DSL_PERMS,		/* ZAP */
177 	DMU_OT_ACL,			/* ACL */
178 	DMU_OT_SYSACL,			/* SYSACL */
179 	DMU_OT_FUID,			/* FUID table (Packed NVLIST UINT8) */
180 	DMU_OT_FUID_SIZE,		/* FUID table size UINT64 */
181 	DMU_OT_NEXT_CLONES,		/* ZAP */
182 	DMU_OT_SCAN_QUEUE,		/* ZAP */
183 	DMU_OT_USERGROUP_USED,		/* ZAP */
184 	DMU_OT_USERGROUP_QUOTA,		/* ZAP */
185 	DMU_OT_USERREFS,		/* ZAP */
186 	DMU_OT_DDT_ZAP,			/* ZAP */
187 	DMU_OT_DDT_STATS,		/* ZAP */
188 	DMU_OT_SA,			/* System attr */
189 	DMU_OT_SA_MASTER_NODE,		/* ZAP */
190 	DMU_OT_SA_ATTR_REGISTRATION,	/* ZAP */
191 	DMU_OT_SA_ATTR_LAYOUTS,		/* ZAP */
192 	DMU_OT_SCAN_XLATE,		/* ZAP */
193 	DMU_OT_DEDUP,			/* fake dedup BP from ddt_bp_create() */
194 	DMU_OT_DEADLIST,		/* ZAP */
195 	DMU_OT_DEADLIST_HDR,		/* UINT64 */
196 	DMU_OT_DSL_CLONES,		/* ZAP */
197 	DMU_OT_BPOBJ_SUBOBJ,		/* UINT64 */
198 	/*
199 	 * Do not allocate new object types here. Doing so makes the on-disk
200 	 * format incompatible with any other format that uses the same object
201 	 * type number.
202 	 *
203 	 * When creating an object which does not have one of the above types
204 	 * use the DMU_OTN_* type with the correct byteswap and metadata
205 	 * values.
206 	 *
207 	 * The DMU_OTN_* types do not have entries in the dmu_ot table,
208 	 * use the DMU_OT_IS_METDATA() and DMU_OT_BYTESWAP() macros instead
209 	 * of indexing into dmu_ot directly (this works for both DMU_OT_* types
210 	 * and DMU_OTN_* types).
211 	 */
212 	DMU_OT_NUMTYPES,
213 
214 	/*
215 	 * Names for valid types declared with DMU_OT().
216 	 */
217 	DMU_OTN_UINT8_DATA = DMU_OT(DMU_BSWAP_UINT8, B_FALSE),
218 	DMU_OTN_UINT8_METADATA = DMU_OT(DMU_BSWAP_UINT8, B_TRUE),
219 	DMU_OTN_UINT16_DATA = DMU_OT(DMU_BSWAP_UINT16, B_FALSE),
220 	DMU_OTN_UINT16_METADATA = DMU_OT(DMU_BSWAP_UINT16, B_TRUE),
221 	DMU_OTN_UINT32_DATA = DMU_OT(DMU_BSWAP_UINT32, B_FALSE),
222 	DMU_OTN_UINT32_METADATA = DMU_OT(DMU_BSWAP_UINT32, B_TRUE),
223 	DMU_OTN_UINT64_DATA = DMU_OT(DMU_BSWAP_UINT64, B_FALSE),
224 	DMU_OTN_UINT64_METADATA = DMU_OT(DMU_BSWAP_UINT64, B_TRUE),
225 	DMU_OTN_ZAP_DATA = DMU_OT(DMU_BSWAP_ZAP, B_FALSE),
226 	DMU_OTN_ZAP_METADATA = DMU_OT(DMU_BSWAP_ZAP, B_TRUE),
227 } dmu_object_type_t;
228 
229 typedef enum txg_how {
230 	TXG_WAIT = 1,
231 	TXG_NOWAIT,
232 	TXG_WAITED,
233 } txg_how_t;
234 
235 void byteswap_uint64_array(void *buf, size_t size);
236 void byteswap_uint32_array(void *buf, size_t size);
237 void byteswap_uint16_array(void *buf, size_t size);
238 void byteswap_uint8_array(void *buf, size_t size);
239 void zap_byteswap(void *buf, size_t size);
240 void zfs_oldacl_byteswap(void *buf, size_t size);
241 void zfs_acl_byteswap(void *buf, size_t size);
242 void zfs_znode_byteswap(void *buf, size_t size);
243 
244 #define	DS_FIND_SNAPSHOTS	(1<<0)
245 #define	DS_FIND_CHILDREN	(1<<1)
246 
247 /*
248  * The maximum number of bytes that can be accessed as part of one
249  * operation, including metadata.
250  */
251 #define	DMU_MAX_ACCESS (10<<20) /* 10MB */
252 #define	DMU_MAX_DELETEBLKCNT (20480) /* ~5MB of indirect blocks */
253 
254 #define	DMU_USERUSED_OBJECT	(-1ULL)
255 #define	DMU_GROUPUSED_OBJECT	(-2ULL)
256 
257 /*
258  * artificial blkids for bonus buffer and spill blocks
259  */
260 #define	DMU_BONUS_BLKID		(-1ULL)
261 #define	DMU_SPILL_BLKID		(-2ULL)
262 /*
263  * Public routines to create, destroy, open, and close objsets.
264  */
265 int dmu_objset_hold(const char *name, void *tag, objset_t **osp);
266 int dmu_objset_own(const char *name, dmu_objset_type_t type,
267     boolean_t readonly, void *tag, objset_t **osp);
268 void dmu_objset_rele(objset_t *os, void *tag);
269 void dmu_objset_disown(objset_t *os, void *tag);
270 int dmu_objset_open_ds(struct dsl_dataset *ds, objset_t **osp);
271 
272 void dmu_objset_evict_dbufs(objset_t *os);
273 int dmu_objset_create(const char *name, dmu_objset_type_t type, uint64_t flags,
274     void (*func)(objset_t *os, void *arg, cred_t *cr, dmu_tx_t *tx), void *arg);
275 int dmu_objset_clone(const char *name, const char *origin);
276 int dsl_destroy_snapshots_nvl(struct nvlist *snaps, boolean_t defer,
277     struct nvlist *errlist);
278 int dmu_objset_snapshot_one(const char *fsname, const char *snapname);
279 int dmu_objset_snapshot_tmp(const char *, const char *, int);
280 int dmu_objset_find(char *name, int func(const char *, void *), void *arg,
281     int flags);
282 void dmu_objset_byteswap(void *buf, size_t size);
283 int dsl_dataset_rename_snapshot(const char *fsname,
284     const char *oldsnapname, const char *newsnapname, boolean_t recursive);
285 
286 typedef struct dmu_buf {
287 	uint64_t db_object;		/* object that this buffer is part of */
288 	uint64_t db_offset;		/* byte offset in this object */
289 	uint64_t db_size;		/* size of buffer in bytes */
290 	void *db_data;			/* data in buffer */
291 } dmu_buf_t;
292 
293 typedef void dmu_buf_evict_func_t(struct dmu_buf *db, void *user_ptr);
294 
295 /*
296  * The names of zap entries in the DIRECTORY_OBJECT of the MOS.
297  */
298 #define	DMU_POOL_DIRECTORY_OBJECT	1
299 #define	DMU_POOL_CONFIG			"config"
300 #define	DMU_POOL_FEATURES_FOR_WRITE	"features_for_write"
301 #define	DMU_POOL_FEATURES_FOR_READ	"features_for_read"
302 #define	DMU_POOL_FEATURE_DESCRIPTIONS	"feature_descriptions"
303 #define	DMU_POOL_FEATURE_ENABLED_TXG	"feature_enabled_txg"
304 #define	DMU_POOL_ROOT_DATASET		"root_dataset"
305 #define	DMU_POOL_SYNC_BPOBJ		"sync_bplist"
306 #define	DMU_POOL_ERRLOG_SCRUB		"errlog_scrub"
307 #define	DMU_POOL_ERRLOG_LAST		"errlog_last"
308 #define	DMU_POOL_SPARES			"spares"
309 #define	DMU_POOL_DEFLATE		"deflate"
310 #define	DMU_POOL_HISTORY		"history"
311 #define	DMU_POOL_PROPS			"pool_props"
312 #define	DMU_POOL_L2CACHE		"l2cache"
313 #define	DMU_POOL_TMP_USERREFS		"tmp_userrefs"
314 #define	DMU_POOL_DDT			"DDT-%s-%s-%s"
315 #define	DMU_POOL_DDT_STATS		"DDT-statistics"
316 #define	DMU_POOL_CREATION_VERSION	"creation_version"
317 #define	DMU_POOL_SCAN			"scan"
318 #define	DMU_POOL_FREE_BPOBJ		"free_bpobj"
319 #define	DMU_POOL_BPTREE_OBJ		"bptree_obj"
320 #define	DMU_POOL_EMPTY_BPOBJ		"empty_bpobj"
321 
322 /*
323  * Allocate an object from this objset.  The range of object numbers
324  * available is (0, DN_MAX_OBJECT).  Object 0 is the meta-dnode.
325  *
326  * The transaction must be assigned to a txg.  The newly allocated
327  * object will be "held" in the transaction (ie. you can modify the
328  * newly allocated object in this transaction).
329  *
330  * dmu_object_alloc() chooses an object and returns it in *objectp.
331  *
332  * dmu_object_claim() allocates a specific object number.  If that
333  * number is already allocated, it fails and returns EEXIST.
334  *
335  * Return 0 on success, or ENOSPC or EEXIST as specified above.
336  */
337 uint64_t dmu_object_alloc(objset_t *os, dmu_object_type_t ot,
338     int blocksize, dmu_object_type_t bonus_type, int bonus_len, dmu_tx_t *tx);
339 int dmu_object_claim(objset_t *os, uint64_t object, dmu_object_type_t ot,
340     int blocksize, dmu_object_type_t bonus_type, int bonus_len, dmu_tx_t *tx);
341 int dmu_object_reclaim(objset_t *os, uint64_t object, dmu_object_type_t ot,
342     int blocksize, dmu_object_type_t bonustype, int bonuslen);
343 
344 /*
345  * Free an object from this objset.
346  *
347  * The object's data will be freed as well (ie. you don't need to call
348  * dmu_free(object, 0, -1, tx)).
349  *
350  * The object need not be held in the transaction.
351  *
352  * If there are any holds on this object's buffers (via dmu_buf_hold()),
353  * or tx holds on the object (via dmu_tx_hold_object()), you can not
354  * free it; it fails and returns EBUSY.
355  *
356  * If the object is not allocated, it fails and returns ENOENT.
357  *
358  * Return 0 on success, or EBUSY or ENOENT as specified above.
359  */
360 int dmu_object_free(objset_t *os, uint64_t object, dmu_tx_t *tx);
361 
362 /*
363  * Find the next allocated or free object.
364  *
365  * The objectp parameter is in-out.  It will be updated to be the next
366  * object which is allocated.  Ignore objects which have not been
367  * modified since txg.
368  *
369  * XXX Can only be called on a objset with no dirty data.
370  *
371  * Returns 0 on success, or ENOENT if there are no more objects.
372  */
373 int dmu_object_next(objset_t *os, uint64_t *objectp,
374     boolean_t hole, uint64_t txg);
375 
376 /*
377  * Set the data blocksize for an object.
378  *
379  * The object cannot have any blocks allcated beyond the first.  If
380  * the first block is allocated already, the new size must be greater
381  * than the current block size.  If these conditions are not met,
382  * ENOTSUP will be returned.
383  *
384  * Returns 0 on success, or EBUSY if there are any holds on the object
385  * contents, or ENOTSUP as described above.
386  */
387 int dmu_object_set_blocksize(objset_t *os, uint64_t object, uint64_t size,
388     int ibs, dmu_tx_t *tx);
389 
390 /*
391  * Set the checksum property on a dnode.  The new checksum algorithm will
392  * apply to all newly written blocks; existing blocks will not be affected.
393  */
394 void dmu_object_set_checksum(objset_t *os, uint64_t object, uint8_t checksum,
395     dmu_tx_t *tx);
396 
397 /*
398  * Set the compress property on a dnode.  The new compression algorithm will
399  * apply to all newly written blocks; existing blocks will not be affected.
400  */
401 void dmu_object_set_compress(objset_t *os, uint64_t object, uint8_t compress,
402     dmu_tx_t *tx);
403 
404 void
405 dmu_write_embedded(objset_t *os, uint64_t object, uint64_t offset,
406     void *data, uint8_t etype, uint8_t comp, int uncompressed_size,
407     int compressed_size, int byteorder, dmu_tx_t *tx);
408 
409 /*
410  * Decide how to write a block: checksum, compression, number of copies, etc.
411  */
412 #define	WP_NOFILL	0x1
413 #define	WP_DMU_SYNC	0x2
414 #define	WP_SPILL	0x4
415 
416 void dmu_write_policy(objset_t *os, struct dnode *dn, int level, int wp,
417     struct zio_prop *zp);
418 /*
419  * The bonus data is accessed more or less like a regular buffer.
420  * You must dmu_bonus_hold() to get the buffer, which will give you a
421  * dmu_buf_t with db_offset==-1ULL, and db_size = the size of the bonus
422  * data.  As with any normal buffer, you must call dmu_buf_read() to
423  * read db_data, dmu_buf_will_dirty() before modifying it, and the
424  * object must be held in an assigned transaction before calling
425  * dmu_buf_will_dirty.  You may use dmu_buf_set_user() on the bonus
426  * buffer as well.  You must release your hold with dmu_buf_rele().
427  *
428  * Returns ENOENT, EIO, or 0.
429  */
430 int dmu_bonus_hold(objset_t *os, uint64_t object, void *tag, dmu_buf_t **);
431 int dmu_bonus_max(void);
432 int dmu_set_bonus(dmu_buf_t *, int, dmu_tx_t *);
433 int dmu_set_bonustype(dmu_buf_t *, dmu_object_type_t, dmu_tx_t *);
434 dmu_object_type_t dmu_get_bonustype(dmu_buf_t *);
435 int dmu_rm_spill(objset_t *, uint64_t, dmu_tx_t *);
436 
437 /*
438  * Special spill buffer support used by "SA" framework
439  */
440 
441 int dmu_spill_hold_by_bonus(dmu_buf_t *bonus, void *tag, dmu_buf_t **dbp);
442 int dmu_spill_hold_by_dnode(struct dnode *dn, uint32_t flags,
443     void *tag, dmu_buf_t **dbp);
444 int dmu_spill_hold_existing(dmu_buf_t *bonus, void *tag, dmu_buf_t **dbp);
445 
446 /*
447  * Obtain the DMU buffer from the specified object which contains the
448  * specified offset.  dmu_buf_hold() puts a "hold" on the buffer, so
449  * that it will remain in memory.  You must release the hold with
450  * dmu_buf_rele().  You musn't access the dmu_buf_t after releasing your
451  * hold.  You must have a hold on any dmu_buf_t* you pass to the DMU.
452  *
453  * You must call dmu_buf_read, dmu_buf_will_dirty, or dmu_buf_will_fill
454  * on the returned buffer before reading or writing the buffer's
455  * db_data.  The comments for those routines describe what particular
456  * operations are valid after calling them.
457  *
458  * The object number must be a valid, allocated object number.
459  */
460 int dmu_buf_hold(objset_t *os, uint64_t object, uint64_t offset,
461     void *tag, dmu_buf_t **, int flags);
462 void dmu_buf_add_ref(dmu_buf_t *db, void* tag);
463 void dmu_buf_rele(dmu_buf_t *db, void *tag);
464 uint64_t dmu_buf_refcount(dmu_buf_t *db);
465 
466 /*
467  * dmu_buf_hold_array holds the DMU buffers which contain all bytes in a
468  * range of an object.  A pointer to an array of dmu_buf_t*'s is
469  * returned (in *dbpp).
470  *
471  * dmu_buf_rele_array releases the hold on an array of dmu_buf_t*'s, and
472  * frees the array.  The hold on the array of buffers MUST be released
473  * with dmu_buf_rele_array.  You can NOT release the hold on each buffer
474  * individually with dmu_buf_rele.
475  */
476 int dmu_buf_hold_array_by_bonus(dmu_buf_t *db, uint64_t offset,
477     uint64_t length, int read, void *tag, int *numbufsp, dmu_buf_t ***dbpp);
478 void dmu_buf_rele_array(dmu_buf_t **, int numbufs, void *tag);
479 
480 /*
481  * Returns NULL on success, or the existing user ptr if it's already
482  * been set.
483  *
484  * user_ptr is for use by the user and can be obtained via dmu_buf_get_user().
485  *
486  * user_data_ptr_ptr should be NULL, or a pointer to a pointer which
487  * will be set to db->db_data when you are allowed to access it.  Note
488  * that db->db_data (the pointer) can change when you do dmu_buf_read(),
489  * dmu_buf_tryupgrade(), dmu_buf_will_dirty(), or dmu_buf_will_fill().
490  * *user_data_ptr_ptr will be set to the new value when it changes.
491  *
492  * If non-NULL, pageout func will be called when this buffer is being
493  * excised from the cache, so that you can clean up the data structure
494  * pointed to by user_ptr.
495  *
496  * dmu_evict_user() will call the pageout func for all buffers in a
497  * objset with a given pageout func.
498  */
499 void *dmu_buf_set_user(dmu_buf_t *db, void *user_ptr, void *user_data_ptr_ptr,
500     dmu_buf_evict_func_t *pageout_func);
501 /*
502  * set_user_ie is the same as set_user, but request immediate eviction
503  * when hold count goes to zero.
504  */
505 void *dmu_buf_set_user_ie(dmu_buf_t *db, void *user_ptr,
506     void *user_data_ptr_ptr, dmu_buf_evict_func_t *pageout_func);
507 void *dmu_buf_update_user(dmu_buf_t *db_fake, void *old_user_ptr,
508     void *user_ptr, void *user_data_ptr_ptr,
509     dmu_buf_evict_func_t *pageout_func);
510 void dmu_evict_user(objset_t *os, dmu_buf_evict_func_t *func);
511 
512 /*
513  * Returns the user_ptr set with dmu_buf_set_user(), or NULL if not set.
514  */
515 void *dmu_buf_get_user(dmu_buf_t *db);
516 
517 /*
518  * Returns the blkptr associated with this dbuf, or NULL if not set.
519  */
520 struct blkptr *dmu_buf_get_blkptr(dmu_buf_t *db);
521 
522 /*
523  * Indicate that you are going to modify the buffer's data (db_data).
524  *
525  * The transaction (tx) must be assigned to a txg (ie. you've called
526  * dmu_tx_assign()).  The buffer's object must be held in the tx
527  * (ie. you've called dmu_tx_hold_object(tx, db->db_object)).
528  */
529 void dmu_buf_will_dirty(dmu_buf_t *db, dmu_tx_t *tx);
530 
531 /*
532  * Tells if the given dbuf is freeable.
533  */
534 boolean_t dmu_buf_freeable(dmu_buf_t *);
535 
536 /*
537  * You must create a transaction, then hold the objects which you will
538  * (or might) modify as part of this transaction.  Then you must assign
539  * the transaction to a transaction group.  Once the transaction has
540  * been assigned, you can modify buffers which belong to held objects as
541  * part of this transaction.  You can't modify buffers before the
542  * transaction has been assigned; you can't modify buffers which don't
543  * belong to objects which this transaction holds; you can't hold
544  * objects once the transaction has been assigned.  You may hold an
545  * object which you are going to free (with dmu_object_free()), but you
546  * don't have to.
547  *
548  * You can abort the transaction before it has been assigned.
549  *
550  * Note that you may hold buffers (with dmu_buf_hold) at any time,
551  * regardless of transaction state.
552  */
553 
554 #define	DMU_NEW_OBJECT	(-1ULL)
555 #define	DMU_OBJECT_END	(-1ULL)
556 
557 dmu_tx_t *dmu_tx_create(objset_t *os);
558 void dmu_tx_hold_write(dmu_tx_t *tx, uint64_t object, uint64_t off, int len);
559 void dmu_tx_hold_free(dmu_tx_t *tx, uint64_t object, uint64_t off,
560     uint64_t len);
561 void dmu_tx_hold_zap(dmu_tx_t *tx, uint64_t object, int add, const char *name);
562 void dmu_tx_hold_bonus(dmu_tx_t *tx, uint64_t object);
563 void dmu_tx_hold_spill(dmu_tx_t *tx, uint64_t object);
564 void dmu_tx_hold_sa(dmu_tx_t *tx, struct sa_handle *hdl, boolean_t may_grow);
565 void dmu_tx_hold_sa_create(dmu_tx_t *tx, int total_size);
566 void dmu_tx_abort(dmu_tx_t *tx);
567 int dmu_tx_assign(dmu_tx_t *tx, enum txg_how txg_how);
568 void dmu_tx_wait(dmu_tx_t *tx);
569 void dmu_tx_commit(dmu_tx_t *tx);
570 void dmu_tx_mark_netfree(dmu_tx_t *tx);
571 
572 /*
573  * To register a commit callback, dmu_tx_callback_register() must be called.
574  *
575  * dcb_data is a pointer to caller private data that is passed on as a
576  * callback parameter. The caller is responsible for properly allocating and
577  * freeing it.
578  *
579  * When registering a callback, the transaction must be already created, but
580  * it cannot be committed or aborted. It can be assigned to a txg or not.
581  *
582  * The callback will be called after the transaction has been safely written
583  * to stable storage and will also be called if the dmu_tx is aborted.
584  * If there is any error which prevents the transaction from being committed to
585  * disk, the callback will be called with a value of error != 0.
586  */
587 typedef void dmu_tx_callback_func_t(void *dcb_data, int error);
588 
589 void dmu_tx_callback_register(dmu_tx_t *tx, dmu_tx_callback_func_t *dcb_func,
590     void *dcb_data);
591 
592 /*
593  * Free up the data blocks for a defined range of a file.  If size is
594  * -1, the range from offset to end-of-file is freed.
595  */
596 int dmu_free_range(objset_t *os, uint64_t object, uint64_t offset,
597 	uint64_t size, dmu_tx_t *tx);
598 int dmu_free_long_range(objset_t *os, uint64_t object, uint64_t offset,
599 	uint64_t size);
600 int dmu_free_long_object(objset_t *os, uint64_t object);
601 
602 /*
603  * Convenience functions.
604  *
605  * Canfail routines will return 0 on success, or an errno if there is a
606  * nonrecoverable I/O error.
607  */
608 #define	DMU_READ_PREFETCH	0 /* prefetch */
609 #define	DMU_READ_NO_PREFETCH	1 /* don't prefetch */
610 int dmu_read(objset_t *os, uint64_t object, uint64_t offset, uint64_t size,
611 	void *buf, uint32_t flags);
612 void dmu_write(objset_t *os, uint64_t object, uint64_t offset, uint64_t size,
613 	const void *buf, dmu_tx_t *tx);
614 void dmu_prealloc(objset_t *os, uint64_t object, uint64_t offset, uint64_t size,
615 	dmu_tx_t *tx);
616 int dmu_read_uio(objset_t *os, uint64_t object, struct uio *uio, uint64_t size);
617 int dmu_write_uio(objset_t *os, uint64_t object, struct uio *uio, uint64_t size,
618     dmu_tx_t *tx);
619 int dmu_write_uio_dbuf(dmu_buf_t *zdb, struct uio *uio, uint64_t size,
620     dmu_tx_t *tx);
621 int dmu_write_pages(objset_t *os, uint64_t object, uint64_t offset,
622     uint64_t size, struct page *pp, dmu_tx_t *tx);
623 struct arc_buf *dmu_request_arcbuf(dmu_buf_t *handle, int size);
624 void dmu_return_arcbuf(struct arc_buf *buf);
625 void dmu_assign_arcbuf(dmu_buf_t *handle, uint64_t offset, struct arc_buf *buf,
626     dmu_tx_t *tx);
627 int dmu_xuio_init(struct xuio *uio, int niov);
628 void dmu_xuio_fini(struct xuio *uio);
629 int dmu_xuio_add(struct xuio *uio, struct arc_buf *abuf, offset_t off,
630     size_t n);
631 int dmu_xuio_cnt(struct xuio *uio);
632 struct arc_buf *dmu_xuio_arcbuf(struct xuio *uio, int i);
633 void dmu_xuio_clear(struct xuio *uio, int i);
634 void xuio_stat_wbuf_copied();
635 void xuio_stat_wbuf_nocopy();
636 
637 extern int zfs_prefetch_disable;
638 
639 /*
640  * Asynchronously try to read in the data.
641  */
642 void dmu_prefetch(objset_t *os, uint64_t object, uint64_t offset,
643     uint64_t len);
644 
645 typedef struct dmu_object_info {
646 	/* All sizes are in bytes unless otherwise indicated. */
647 	uint32_t doi_data_block_size;
648 	uint32_t doi_metadata_block_size;
649 	dmu_object_type_t doi_type;
650 	dmu_object_type_t doi_bonus_type;
651 	uint64_t doi_bonus_size;
652 	uint8_t doi_indirection;		/* 2 = dnode->indirect->data */
653 	uint8_t doi_checksum;
654 	uint8_t doi_compress;
655 	uint8_t doi_pad[5];
656 	uint64_t doi_physical_blocks_512;	/* data + metadata, 512b blks */
657 	uint64_t doi_max_offset;
658 	uint64_t doi_fill_count;		/* number of non-empty blocks */
659 } dmu_object_info_t;
660 
661 typedef void arc_byteswap_func_t(void *buf, size_t size);
662 
663 typedef struct dmu_object_type_info {
664 	dmu_object_byteswap_t	ot_byteswap;
665 	boolean_t		ot_metadata;
666 	char			*ot_name;
667 } dmu_object_type_info_t;
668 
669 typedef struct dmu_object_byteswap_info {
670 	arc_byteswap_func_t	*ob_func;
671 	char			*ob_name;
672 } dmu_object_byteswap_info_t;
673 
674 extern const dmu_object_type_info_t dmu_ot[DMU_OT_NUMTYPES];
675 extern const dmu_object_byteswap_info_t dmu_ot_byteswap[DMU_BSWAP_NUMFUNCS];
676 
677 /*
678  * Get information on a DMU object.
679  *
680  * Return 0 on success or ENOENT if object is not allocated.
681  *
682  * If doi is NULL, just indicates whether the object exists.
683  */
684 int dmu_object_info(objset_t *os, uint64_t object, dmu_object_info_t *doi);
685 /* Like dmu_object_info, but faster if you have a held dnode in hand. */
686 void dmu_object_info_from_dnode(struct dnode *dn, dmu_object_info_t *doi);
687 /* Like dmu_object_info, but faster if you have a held dbuf in hand. */
688 void dmu_object_info_from_db(dmu_buf_t *db, dmu_object_info_t *doi);
689 /*
690  * Like dmu_object_info_from_db, but faster still when you only care about
691  * the size.  This is specifically optimized for zfs_getattr().
692  */
693 void dmu_object_size_from_db(dmu_buf_t *db, uint32_t *blksize,
694     u_longlong_t *nblk512);
695 
696 typedef struct dmu_objset_stats {
697 	uint64_t dds_num_clones; /* number of clones of this */
698 	uint64_t dds_creation_txg;
699 	uint64_t dds_guid;
700 	dmu_objset_type_t dds_type;
701 	uint8_t dds_is_snapshot;
702 	uint8_t dds_inconsistent;
703 	char dds_origin[MAXNAMELEN];
704 } dmu_objset_stats_t;
705 
706 /*
707  * Get stats on a dataset.
708  */
709 void dmu_objset_fast_stat(objset_t *os, dmu_objset_stats_t *stat);
710 
711 /*
712  * Add entries to the nvlist for all the objset's properties.  See
713  * zfs_prop_table[] and zfs(1m) for details on the properties.
714  */
715 void dmu_objset_stats(objset_t *os, struct nvlist *nv);
716 
717 /*
718  * Get the space usage statistics for statvfs().
719  *
720  * refdbytes is the amount of space "referenced" by this objset.
721  * availbytes is the amount of space available to this objset, taking
722  * into account quotas & reservations, assuming that no other objsets
723  * use the space first.  These values correspond to the 'referenced' and
724  * 'available' properties, described in the zfs(1m) manpage.
725  *
726  * usedobjs and availobjs are the number of objects currently allocated,
727  * and available.
728  */
729 void dmu_objset_space(objset_t *os, uint64_t *refdbytesp, uint64_t *availbytesp,
730     uint64_t *usedobjsp, uint64_t *availobjsp);
731 
732 /*
733  * The fsid_guid is a 56-bit ID that can change to avoid collisions.
734  * (Contrast with the ds_guid which is a 64-bit ID that will never
735  * change, so there is a small probability that it will collide.)
736  */
737 uint64_t dmu_objset_fsid_guid(objset_t *os);
738 
739 /*
740  * Get the [cm]time for an objset's snapshot dir
741  */
742 timestruc_t dmu_objset_snap_cmtime(objset_t *os);
743 
744 int dmu_objset_is_snapshot(objset_t *os);
745 
746 extern struct spa *dmu_objset_spa(objset_t *os);
747 extern struct zilog *dmu_objset_zil(objset_t *os);
748 extern struct dsl_pool *dmu_objset_pool(objset_t *os);
749 extern struct dsl_dataset *dmu_objset_ds(objset_t *os);
750 extern void dmu_objset_name(objset_t *os, char *buf);
751 extern dmu_objset_type_t dmu_objset_type(objset_t *os);
752 extern uint64_t dmu_objset_id(objset_t *os);
753 extern zfs_sync_type_t dmu_objset_syncprop(objset_t *os);
754 extern zfs_logbias_op_t dmu_objset_logbias(objset_t *os);
755 extern int dmu_snapshot_list_next(objset_t *os, int namelen, char *name,
756     uint64_t *id, uint64_t *offp, boolean_t *case_conflict);
757 extern int dmu_snapshot_realname(objset_t *os, char *name, char *real,
758     int maxlen, boolean_t *conflict);
759 extern int dmu_dir_list_next(objset_t *os, int namelen, char *name,
760     uint64_t *idp, uint64_t *offp);
761 
762 typedef int objset_used_cb_t(dmu_object_type_t bonustype,
763     void *bonus, uint64_t *userp, uint64_t *groupp);
764 extern void dmu_objset_register_type(dmu_objset_type_t ost,
765     objset_used_cb_t *cb);
766 extern void dmu_objset_set_user(objset_t *os, void *user_ptr);
767 extern void *dmu_objset_get_user(objset_t *os);
768 
769 /*
770  * Return the txg number for the given assigned transaction.
771  */
772 uint64_t dmu_tx_get_txg(dmu_tx_t *tx);
773 
774 /*
775  * Synchronous write.
776  * If a parent zio is provided this function initiates a write on the
777  * provided buffer as a child of the parent zio.
778  * In the absence of a parent zio, the write is completed synchronously.
779  * At write completion, blk is filled with the bp of the written block.
780  * Note that while the data covered by this function will be on stable
781  * storage when the write completes this new data does not become a
782  * permanent part of the file until the associated transaction commits.
783  */
784 
785 /*
786  * {zfs,zvol,ztest}_get_done() args
787  */
788 typedef struct zgd {
789 	struct zilog	*zgd_zilog;
790 	struct blkptr	*zgd_bp;
791 	dmu_buf_t	*zgd_db;
792 	struct rl	*zgd_rl;
793 	void		*zgd_private;
794 } zgd_t;
795 
796 typedef void dmu_sync_cb_t(zgd_t *arg, int error);
797 int dmu_sync(struct zio *zio, uint64_t txg, dmu_sync_cb_t *done, zgd_t *zgd);
798 
799 /*
800  * Find the next hole or data block in file starting at *off
801  * Return found offset in *off. Return ESRCH for end of file.
802  */
803 int dmu_offset_next(objset_t *os, uint64_t object, boolean_t hole,
804     uint64_t *off);
805 
806 /*
807  * Initial setup and final teardown.
808  */
809 extern void dmu_init(void);
810 extern void dmu_fini(void);
811 
812 typedef void (*dmu_traverse_cb_t)(objset_t *os, void *arg, struct blkptr *bp,
813     uint64_t object, uint64_t offset, int len);
814 void dmu_traverse_objset(objset_t *os, uint64_t txg_start,
815     dmu_traverse_cb_t cb, void *arg);
816 
817 int dmu_diff(const char *tosnap_name, const char *fromsnap_name,
818     struct vnode *vp, offset_t *offp);
819 
820 /* CRC64 table */
821 #define	ZFS_CRC64_POLY	0xC96C5795D7870F42ULL	/* ECMA-182, reflected form */
822 extern uint64_t zfs_crc64_table[256];
823 
824 extern int zfs_mdcomp_disable;
825 
826 #ifdef	__cplusplus
827 }
828 #endif
829 
830 #endif	/* _SYS_DMU_H */
831