xref: /illumos-gate/usr/src/uts/common/fs/zfs/sys/dmu.h (revision 5cabbc6b49070407fb9610cfe73d4c0e0dea3e77)
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, 2017 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  * Copyright (c) 2014 Spectra Logic Corporation, All rights reserved.
30  * Copyright 2013 Saso Kiselkov. All rights reserved.
31  * Copyright (c) 2014 Integros [integros.com]
32  */
33 
34 /* Portions Copyright 2010 Robert Milkowski */
35 
36 #ifndef	_SYS_DMU_H
37 #define	_SYS_DMU_H
38 
39 /*
40  * This file describes the interface that the DMU provides for its
41  * consumers.
42  *
43  * The DMU also interacts with the SPA.  That interface is described in
44  * dmu_spa.h.
45  */
46 
47 #include <sys/zfs_context.h>
48 #include <sys/inttypes.h>
49 #include <sys/cred.h>
50 #include <sys/fs/zfs.h>
51 #include <sys/zio_compress.h>
52 #include <sys/zio_priority.h>
53 
54 #ifdef	__cplusplus
55 extern "C" {
56 #endif
57 
58 struct uio;
59 struct xuio;
60 struct page;
61 struct vnode;
62 struct spa;
63 struct zilog;
64 struct zio;
65 struct blkptr;
66 struct zap_cursor;
67 struct dsl_dataset;
68 struct dsl_pool;
69 struct dnode;
70 struct drr_begin;
71 struct drr_end;
72 struct zbookmark_phys;
73 struct spa;
74 struct nvlist;
75 struct arc_buf;
76 struct zio_prop;
77 struct sa_handle;
78 
79 typedef struct objset objset_t;
80 typedef struct dmu_tx dmu_tx_t;
81 typedef struct dsl_dir dsl_dir_t;
82 typedef struct dnode dnode_t;
83 
84 typedef enum dmu_object_byteswap {
85 	DMU_BSWAP_UINT8,
86 	DMU_BSWAP_UINT16,
87 	DMU_BSWAP_UINT32,
88 	DMU_BSWAP_UINT64,
89 	DMU_BSWAP_ZAP,
90 	DMU_BSWAP_DNODE,
91 	DMU_BSWAP_OBJSET,
92 	DMU_BSWAP_ZNODE,
93 	DMU_BSWAP_OLDACL,
94 	DMU_BSWAP_ACL,
95 	/*
96 	 * Allocating a new byteswap type number makes the on-disk format
97 	 * incompatible with any other format that uses the same number.
98 	 *
99 	 * Data can usually be structured to work with one of the
100 	 * DMU_BSWAP_UINT* or DMU_BSWAP_ZAP types.
101 	 */
102 	DMU_BSWAP_NUMFUNCS
103 } dmu_object_byteswap_t;
104 
105 #define	DMU_OT_NEWTYPE 0x80
106 #define	DMU_OT_METADATA 0x40
107 #define	DMU_OT_BYTESWAP_MASK 0x3f
108 
109 /*
110  * Defines a uint8_t object type. Object types specify if the data
111  * in the object is metadata (boolean) and how to byteswap the data
112  * (dmu_object_byteswap_t).
113  */
114 #define	DMU_OT(byteswap, metadata) \
115 	(DMU_OT_NEWTYPE | \
116 	((metadata) ? DMU_OT_METADATA : 0) | \
117 	((byteswap) & DMU_OT_BYTESWAP_MASK))
118 
119 #define	DMU_OT_IS_VALID(ot) (((ot) & DMU_OT_NEWTYPE) ? \
120 	((ot) & DMU_OT_BYTESWAP_MASK) < DMU_BSWAP_NUMFUNCS : \
121 	(ot) < DMU_OT_NUMTYPES)
122 
123 #define	DMU_OT_IS_METADATA(ot) (((ot) & DMU_OT_NEWTYPE) ? \
124 	((ot) & DMU_OT_METADATA) : \
125 	dmu_ot[(ot)].ot_metadata)
126 
127 /*
128  * These object types use bp_fill != 1 for their L0 bp's. Therefore they can't
129  * have their data embedded (i.e. use a BP_IS_EMBEDDED() bp), because bp_fill
130  * is repurposed for embedded BPs.
131  */
132 #define	DMU_OT_HAS_FILL(ot) \
133 	((ot) == DMU_OT_DNODE || (ot) == DMU_OT_OBJSET)
134 
135 #define	DMU_OT_BYTESWAP(ot) (((ot) & DMU_OT_NEWTYPE) ? \
136 	((ot) & DMU_OT_BYTESWAP_MASK) : \
137 	dmu_ot[(ot)].ot_byteswap)
138 
139 typedef enum dmu_object_type {
140 	DMU_OT_NONE,
141 	/* general: */
142 	DMU_OT_OBJECT_DIRECTORY,	/* ZAP */
143 	DMU_OT_OBJECT_ARRAY,		/* UINT64 */
144 	DMU_OT_PACKED_NVLIST,		/* UINT8 (XDR by nvlist_pack/unpack) */
145 	DMU_OT_PACKED_NVLIST_SIZE,	/* UINT64 */
146 	DMU_OT_BPOBJ,			/* UINT64 */
147 	DMU_OT_BPOBJ_HDR,		/* UINT64 */
148 	/* spa: */
149 	DMU_OT_SPACE_MAP_HEADER,	/* UINT64 */
150 	DMU_OT_SPACE_MAP,		/* UINT64 */
151 	/* zil: */
152 	DMU_OT_INTENT_LOG,		/* UINT64 */
153 	/* dmu: */
154 	DMU_OT_DNODE,			/* DNODE */
155 	DMU_OT_OBJSET,			/* OBJSET */
156 	/* dsl: */
157 	DMU_OT_DSL_DIR,			/* UINT64 */
158 	DMU_OT_DSL_DIR_CHILD_MAP,	/* ZAP */
159 	DMU_OT_DSL_DS_SNAP_MAP,		/* ZAP */
160 	DMU_OT_DSL_PROPS,		/* ZAP */
161 	DMU_OT_DSL_DATASET,		/* UINT64 */
162 	/* zpl: */
163 	DMU_OT_ZNODE,			/* ZNODE */
164 	DMU_OT_OLDACL,			/* Old ACL */
165 	DMU_OT_PLAIN_FILE_CONTENTS,	/* UINT8 */
166 	DMU_OT_DIRECTORY_CONTENTS,	/* ZAP */
167 	DMU_OT_MASTER_NODE,		/* ZAP */
168 	DMU_OT_UNLINKED_SET,		/* ZAP */
169 	/* zvol: */
170 	DMU_OT_ZVOL,			/* UINT8 */
171 	DMU_OT_ZVOL_PROP,		/* ZAP */
172 	/* other; for testing only! */
173 	DMU_OT_PLAIN_OTHER,		/* UINT8 */
174 	DMU_OT_UINT64_OTHER,		/* UINT64 */
175 	DMU_OT_ZAP_OTHER,		/* ZAP */
176 	/* new object types: */
177 	DMU_OT_ERROR_LOG,		/* ZAP */
178 	DMU_OT_SPA_HISTORY,		/* UINT8 */
179 	DMU_OT_SPA_HISTORY_OFFSETS,	/* spa_his_phys_t */
180 	DMU_OT_POOL_PROPS,		/* ZAP */
181 	DMU_OT_DSL_PERMS,		/* ZAP */
182 	DMU_OT_ACL,			/* ACL */
183 	DMU_OT_SYSACL,			/* SYSACL */
184 	DMU_OT_FUID,			/* FUID table (Packed NVLIST UINT8) */
185 	DMU_OT_FUID_SIZE,		/* FUID table size UINT64 */
186 	DMU_OT_NEXT_CLONES,		/* ZAP */
187 	DMU_OT_SCAN_QUEUE,		/* ZAP */
188 	DMU_OT_USERGROUP_USED,		/* ZAP */
189 	DMU_OT_USERGROUP_QUOTA,		/* ZAP */
190 	DMU_OT_USERREFS,		/* ZAP */
191 	DMU_OT_DDT_ZAP,			/* ZAP */
192 	DMU_OT_DDT_STATS,		/* ZAP */
193 	DMU_OT_SA,			/* System attr */
194 	DMU_OT_SA_MASTER_NODE,		/* ZAP */
195 	DMU_OT_SA_ATTR_REGISTRATION,	/* ZAP */
196 	DMU_OT_SA_ATTR_LAYOUTS,		/* ZAP */
197 	DMU_OT_SCAN_XLATE,		/* ZAP */
198 	DMU_OT_DEDUP,			/* fake dedup BP from ddt_bp_create() */
199 	DMU_OT_DEADLIST,		/* ZAP */
200 	DMU_OT_DEADLIST_HDR,		/* UINT64 */
201 	DMU_OT_DSL_CLONES,		/* ZAP */
202 	DMU_OT_BPOBJ_SUBOBJ,		/* UINT64 */
203 	/*
204 	 * Do not allocate new object types here. Doing so makes the on-disk
205 	 * format incompatible with any other format that uses the same object
206 	 * type number.
207 	 *
208 	 * When creating an object which does not have one of the above types
209 	 * use the DMU_OTN_* type with the correct byteswap and metadata
210 	 * values.
211 	 *
212 	 * The DMU_OTN_* types do not have entries in the dmu_ot table,
213 	 * use the DMU_OT_IS_METDATA() and DMU_OT_BYTESWAP() macros instead
214 	 * of indexing into dmu_ot directly (this works for both DMU_OT_* types
215 	 * and DMU_OTN_* types).
216 	 */
217 	DMU_OT_NUMTYPES,
218 
219 	/*
220 	 * Names for valid types declared with DMU_OT().
221 	 */
222 	DMU_OTN_UINT8_DATA = DMU_OT(DMU_BSWAP_UINT8, B_FALSE),
223 	DMU_OTN_UINT8_METADATA = DMU_OT(DMU_BSWAP_UINT8, B_TRUE),
224 	DMU_OTN_UINT16_DATA = DMU_OT(DMU_BSWAP_UINT16, B_FALSE),
225 	DMU_OTN_UINT16_METADATA = DMU_OT(DMU_BSWAP_UINT16, B_TRUE),
226 	DMU_OTN_UINT32_DATA = DMU_OT(DMU_BSWAP_UINT32, B_FALSE),
227 	DMU_OTN_UINT32_METADATA = DMU_OT(DMU_BSWAP_UINT32, B_TRUE),
228 	DMU_OTN_UINT64_DATA = DMU_OT(DMU_BSWAP_UINT64, B_FALSE),
229 	DMU_OTN_UINT64_METADATA = DMU_OT(DMU_BSWAP_UINT64, B_TRUE),
230 	DMU_OTN_ZAP_DATA = DMU_OT(DMU_BSWAP_ZAP, B_FALSE),
231 	DMU_OTN_ZAP_METADATA = DMU_OT(DMU_BSWAP_ZAP, B_TRUE),
232 } dmu_object_type_t;
233 
234 typedef enum txg_how {
235 	TXG_WAIT = 1,
236 	TXG_NOWAIT,
237 	TXG_WAITED,
238 } txg_how_t;
239 
240 void byteswap_uint64_array(void *buf, size_t size);
241 void byteswap_uint32_array(void *buf, size_t size);
242 void byteswap_uint16_array(void *buf, size_t size);
243 void byteswap_uint8_array(void *buf, size_t size);
244 void zap_byteswap(void *buf, size_t size);
245 void zfs_oldacl_byteswap(void *buf, size_t size);
246 void zfs_acl_byteswap(void *buf, size_t size);
247 void zfs_znode_byteswap(void *buf, size_t size);
248 
249 #define	DS_FIND_SNAPSHOTS	(1<<0)
250 #define	DS_FIND_CHILDREN	(1<<1)
251 #define	DS_FIND_SERIALIZE	(1<<2)
252 
253 /*
254  * The maximum number of bytes that can be accessed as part of one
255  * operation, including metadata.
256  */
257 #define	DMU_MAX_ACCESS (32 * 1024 * 1024) /* 32MB */
258 #define	DMU_MAX_DELETEBLKCNT (20480) /* ~5MB of indirect blocks */
259 
260 #define	DMU_USERUSED_OBJECT	(-1ULL)
261 #define	DMU_GROUPUSED_OBJECT	(-2ULL)
262 
263 /*
264  * artificial blkids for bonus buffer and spill blocks
265  */
266 #define	DMU_BONUS_BLKID		(-1ULL)
267 #define	DMU_SPILL_BLKID		(-2ULL)
268 /*
269  * Public routines to create, destroy, open, and close objsets.
270  */
271 int dmu_objset_hold(const char *name, void *tag, objset_t **osp);
272 int dmu_objset_own(const char *name, dmu_objset_type_t type,
273     boolean_t readonly, void *tag, objset_t **osp);
274 void dmu_objset_rele(objset_t *os, void *tag);
275 void dmu_objset_disown(objset_t *os, void *tag);
276 int dmu_objset_open_ds(struct dsl_dataset *ds, objset_t **osp);
277 
278 void dmu_objset_evict_dbufs(objset_t *os);
279 int dmu_objset_create(const char *name, dmu_objset_type_t type, uint64_t flags,
280     void (*func)(objset_t *os, void *arg, cred_t *cr, dmu_tx_t *tx), void *arg);
281 int dmu_objset_clone(const char *name, const char *origin);
282 int dsl_destroy_snapshots_nvl(struct nvlist *snaps, boolean_t defer,
283     struct nvlist *errlist);
284 int dmu_objset_snapshot_one(const char *fsname, const char *snapname);
285 int dmu_objset_snapshot_tmp(const char *, const char *, int);
286 int dmu_objset_find(char *name, int func(const char *, void *), void *arg,
287     int flags);
288 void dmu_objset_byteswap(void *buf, size_t size);
289 int dsl_dataset_rename_snapshot(const char *fsname,
290     const char *oldsnapname, const char *newsnapname, boolean_t recursive);
291 int dmu_objset_remap_indirects(const char *fsname);
292 
293 typedef struct dmu_buf {
294 	uint64_t db_object;		/* object that this buffer is part of */
295 	uint64_t db_offset;		/* byte offset in this object */
296 	uint64_t db_size;		/* size of buffer in bytes */
297 	void *db_data;			/* data in buffer */
298 } dmu_buf_t;
299 
300 /*
301  * The names of zap entries in the DIRECTORY_OBJECT of the MOS.
302  */
303 #define	DMU_POOL_DIRECTORY_OBJECT	1
304 #define	DMU_POOL_CONFIG			"config"
305 #define	DMU_POOL_FEATURES_FOR_WRITE	"features_for_write"
306 #define	DMU_POOL_FEATURES_FOR_READ	"features_for_read"
307 #define	DMU_POOL_FEATURE_DESCRIPTIONS	"feature_descriptions"
308 #define	DMU_POOL_FEATURE_ENABLED_TXG	"feature_enabled_txg"
309 #define	DMU_POOL_ROOT_DATASET		"root_dataset"
310 #define	DMU_POOL_SYNC_BPOBJ		"sync_bplist"
311 #define	DMU_POOL_ERRLOG_SCRUB		"errlog_scrub"
312 #define	DMU_POOL_ERRLOG_LAST		"errlog_last"
313 #define	DMU_POOL_SPARES			"spares"
314 #define	DMU_POOL_DEFLATE		"deflate"
315 #define	DMU_POOL_HISTORY		"history"
316 #define	DMU_POOL_PROPS			"pool_props"
317 #define	DMU_POOL_L2CACHE		"l2cache"
318 #define	DMU_POOL_TMP_USERREFS		"tmp_userrefs"
319 #define	DMU_POOL_DDT			"DDT-%s-%s-%s"
320 #define	DMU_POOL_DDT_STATS		"DDT-statistics"
321 #define	DMU_POOL_CREATION_VERSION	"creation_version"
322 #define	DMU_POOL_SCAN			"scan"
323 #define	DMU_POOL_FREE_BPOBJ		"free_bpobj"
324 #define	DMU_POOL_BPTREE_OBJ		"bptree_obj"
325 #define	DMU_POOL_EMPTY_BPOBJ		"empty_bpobj"
326 #define	DMU_POOL_CHECKSUM_SALT		"org.illumos:checksum_salt"
327 #define	DMU_POOL_VDEV_ZAP_MAP		"com.delphix:vdev_zap_map"
328 #define	DMU_POOL_REMOVING		"com.delphix:removing"
329 #define	DMU_POOL_OBSOLETE_BPOBJ		"com.delphix:obsolete_bpobj"
330 #define	DMU_POOL_CONDENSING_INDIRECT	"com.delphix:condensing_indirect"
331 
332 /*
333  * Allocate an object from this objset.  The range of object numbers
334  * available is (0, DN_MAX_OBJECT).  Object 0 is the meta-dnode.
335  *
336  * The transaction must be assigned to a txg.  The newly allocated
337  * object will be "held" in the transaction (ie. you can modify the
338  * newly allocated object in this transaction).
339  *
340  * dmu_object_alloc() chooses an object and returns it in *objectp.
341  *
342  * dmu_object_claim() allocates a specific object number.  If that
343  * number is already allocated, it fails and returns EEXIST.
344  *
345  * Return 0 on success, or ENOSPC or EEXIST as specified above.
346  */
347 uint64_t dmu_object_alloc(objset_t *os, dmu_object_type_t ot,
348     int blocksize, dmu_object_type_t bonus_type, int bonus_len, dmu_tx_t *tx);
349 int dmu_object_claim(objset_t *os, uint64_t object, dmu_object_type_t ot,
350     int blocksize, dmu_object_type_t bonus_type, int bonus_len, dmu_tx_t *tx);
351 int dmu_object_reclaim(objset_t *os, uint64_t object, dmu_object_type_t ot,
352     int blocksize, dmu_object_type_t bonustype, int bonuslen, dmu_tx_t *txp);
353 
354 /*
355  * Free an object from this objset.
356  *
357  * The object's data will be freed as well (ie. you don't need to call
358  * dmu_free(object, 0, -1, tx)).
359  *
360  * The object need not be held in the transaction.
361  *
362  * If there are any holds on this object's buffers (via dmu_buf_hold()),
363  * or tx holds on the object (via dmu_tx_hold_object()), you can not
364  * free it; it fails and returns EBUSY.
365  *
366  * If the object is not allocated, it fails and returns ENOENT.
367  *
368  * Return 0 on success, or EBUSY or ENOENT as specified above.
369  */
370 int dmu_object_free(objset_t *os, uint64_t object, dmu_tx_t *tx);
371 
372 /*
373  * Find the next allocated or free object.
374  *
375  * The objectp parameter is in-out.  It will be updated to be the next
376  * object which is allocated.  Ignore objects which have not been
377  * modified since txg.
378  *
379  * XXX Can only be called on a objset with no dirty data.
380  *
381  * Returns 0 on success, or ENOENT if there are no more objects.
382  */
383 int dmu_object_next(objset_t *os, uint64_t *objectp,
384     boolean_t hole, uint64_t txg);
385 
386 /*
387  * Set the data blocksize for an object.
388  *
389  * The object cannot have any blocks allcated beyond the first.  If
390  * the first block is allocated already, the new size must be greater
391  * than the current block size.  If these conditions are not met,
392  * ENOTSUP will be returned.
393  *
394  * Returns 0 on success, or EBUSY if there are any holds on the object
395  * contents, or ENOTSUP as described above.
396  */
397 int dmu_object_set_blocksize(objset_t *os, uint64_t object, uint64_t size,
398     int ibs, dmu_tx_t *tx);
399 
400 /*
401  * Set the checksum property on a dnode.  The new checksum algorithm will
402  * apply to all newly written blocks; existing blocks will not be affected.
403  */
404 void dmu_object_set_checksum(objset_t *os, uint64_t object, uint8_t checksum,
405     dmu_tx_t *tx);
406 
407 /*
408  * Set the compress property on a dnode.  The new compression algorithm will
409  * apply to all newly written blocks; existing blocks will not be affected.
410  */
411 void dmu_object_set_compress(objset_t *os, uint64_t object, uint8_t compress,
412     dmu_tx_t *tx);
413 
414 int dmu_object_remap_indirects(objset_t *os, uint64_t object, uint64_t txg);
415 
416 void
417 dmu_write_embedded(objset_t *os, uint64_t object, uint64_t offset,
418     void *data, uint8_t etype, uint8_t comp, int uncompressed_size,
419     int compressed_size, int byteorder, dmu_tx_t *tx);
420 
421 /*
422  * Decide how to write a block: checksum, compression, number of copies, etc.
423  */
424 #define	WP_NOFILL	0x1
425 #define	WP_DMU_SYNC	0x2
426 #define	WP_SPILL	0x4
427 
428 void dmu_write_policy(objset_t *os, dnode_t *dn, int level, int wp,
429     struct zio_prop *zp);
430 /*
431  * The bonus data is accessed more or less like a regular buffer.
432  * You must dmu_bonus_hold() to get the buffer, which will give you a
433  * dmu_buf_t with db_offset==-1ULL, and db_size = the size of the bonus
434  * data.  As with any normal buffer, you must call dmu_buf_will_dirty()
435  * before modifying it, and the
436  * object must be held in an assigned transaction before calling
437  * dmu_buf_will_dirty.  You may use dmu_buf_set_user() on the bonus
438  * buffer as well.  You must release your hold with dmu_buf_rele().
439  *
440  * Returns ENOENT, EIO, or 0.
441  */
442 int dmu_bonus_hold(objset_t *os, uint64_t object, void *tag, dmu_buf_t **);
443 int dmu_bonus_max(void);
444 int dmu_set_bonus(dmu_buf_t *, int, dmu_tx_t *);
445 int dmu_set_bonustype(dmu_buf_t *, dmu_object_type_t, dmu_tx_t *);
446 dmu_object_type_t dmu_get_bonustype(dmu_buf_t *);
447 int dmu_rm_spill(objset_t *, uint64_t, dmu_tx_t *);
448 
449 /*
450  * Special spill buffer support used by "SA" framework
451  */
452 
453 int dmu_spill_hold_by_bonus(dmu_buf_t *bonus, void *tag, dmu_buf_t **dbp);
454 int dmu_spill_hold_by_dnode(dnode_t *dn, uint32_t flags,
455     void *tag, dmu_buf_t **dbp);
456 int dmu_spill_hold_existing(dmu_buf_t *bonus, void *tag, dmu_buf_t **dbp);
457 
458 /*
459  * Obtain the DMU buffer from the specified object which contains the
460  * specified offset.  dmu_buf_hold() puts a "hold" on the buffer, so
461  * that it will remain in memory.  You must release the hold with
462  * dmu_buf_rele().  You musn't access the dmu_buf_t after releasing your
463  * hold.  You must have a hold on any dmu_buf_t* you pass to the DMU.
464  *
465  * You must call dmu_buf_read, dmu_buf_will_dirty, or dmu_buf_will_fill
466  * on the returned buffer before reading or writing the buffer's
467  * db_data.  The comments for those routines describe what particular
468  * operations are valid after calling them.
469  *
470  * The object number must be a valid, allocated object number.
471  */
472 int dmu_buf_hold(objset_t *os, uint64_t object, uint64_t offset,
473     void *tag, dmu_buf_t **, int flags);
474 int dmu_buf_hold_by_dnode(dnode_t *dn, uint64_t offset,
475     void *tag, dmu_buf_t **dbp, int flags);
476 
477 /*
478  * Add a reference to a dmu buffer that has already been held via
479  * dmu_buf_hold() in the current context.
480  */
481 void dmu_buf_add_ref(dmu_buf_t *db, void* tag);
482 
483 /*
484  * Attempt to add a reference to a dmu buffer that is in an unknown state,
485  * using a pointer that may have been invalidated by eviction processing.
486  * The request will succeed if the passed in dbuf still represents the
487  * same os/object/blkid, is ineligible for eviction, and has at least
488  * one hold by a user other than the syncer.
489  */
490 boolean_t dmu_buf_try_add_ref(dmu_buf_t *, objset_t *os, uint64_t object,
491     uint64_t blkid, void *tag);
492 
493 void dmu_buf_rele(dmu_buf_t *db, void *tag);
494 uint64_t dmu_buf_refcount(dmu_buf_t *db);
495 
496 /*
497  * dmu_buf_hold_array holds the DMU buffers which contain all bytes in a
498  * range of an object.  A pointer to an array of dmu_buf_t*'s is
499  * returned (in *dbpp).
500  *
501  * dmu_buf_rele_array releases the hold on an array of dmu_buf_t*'s, and
502  * frees the array.  The hold on the array of buffers MUST be released
503  * with dmu_buf_rele_array.  You can NOT release the hold on each buffer
504  * individually with dmu_buf_rele.
505  */
506 int dmu_buf_hold_array_by_bonus(dmu_buf_t *db, uint64_t offset,
507     uint64_t length, boolean_t read, void *tag,
508     int *numbufsp, dmu_buf_t ***dbpp);
509 void dmu_buf_rele_array(dmu_buf_t **, int numbufs, void *tag);
510 
511 typedef void dmu_buf_evict_func_t(void *user_ptr);
512 
513 /*
514  * A DMU buffer user object may be associated with a dbuf for the
515  * duration of its lifetime.  This allows the user of a dbuf (client)
516  * to attach private data to a dbuf (e.g. in-core only data such as a
517  * dnode_children_t, zap_t, or zap_leaf_t) and be optionally notified
518  * when that dbuf has been evicted.  Clients typically respond to the
519  * eviction notification by freeing their private data, thus ensuring
520  * the same lifetime for both dbuf and private data.
521  *
522  * The mapping from a dmu_buf_user_t to any client private data is the
523  * client's responsibility.  All current consumers of the API with private
524  * data embed a dmu_buf_user_t as the first member of the structure for
525  * their private data.  This allows conversions between the two types
526  * with a simple cast.  Since the DMU buf user API never needs access
527  * to the private data, other strategies can be employed if necessary
528  * or convenient for the client (e.g. using container_of() to do the
529  * conversion for private data that cannot have the dmu_buf_user_t as
530  * its first member).
531  *
532  * Eviction callbacks are executed without the dbuf mutex held or any
533  * other type of mechanism to guarantee that the dbuf is still available.
534  * For this reason, users must assume the dbuf has already been freed
535  * and not reference the dbuf from the callback context.
536  *
537  * Users requesting "immediate eviction" are notified as soon as the dbuf
538  * is only referenced by dirty records (dirties == holds).  Otherwise the
539  * notification occurs after eviction processing for the dbuf begins.
540  */
541 typedef struct dmu_buf_user {
542 	/*
543 	 * Asynchronous user eviction callback state.
544 	 */
545 	taskq_ent_t	dbu_tqent;
546 
547 	/*
548 	 * This instance's eviction function pointers.
549 	 *
550 	 * dbu_evict_func_sync is called synchronously and then
551 	 * dbu_evict_func_async is executed asynchronously on a taskq.
552 	 */
553 	dmu_buf_evict_func_t *dbu_evict_func_sync;
554 	dmu_buf_evict_func_t *dbu_evict_func_async;
555 #ifdef ZFS_DEBUG
556 	/*
557 	 * Pointer to user's dbuf pointer.  NULL for clients that do
558 	 * not associate a dbuf with their user data.
559 	 *
560 	 * The dbuf pointer is cleared upon eviction so as to catch
561 	 * use-after-evict bugs in clients.
562 	 */
563 	dmu_buf_t **dbu_clear_on_evict_dbufp;
564 #endif
565 } dmu_buf_user_t;
566 
567 /*
568  * Initialize the given dmu_buf_user_t instance with the eviction function
569  * evict_func, to be called when the user is evicted.
570  *
571  * NOTE: This function should only be called once on a given dmu_buf_user_t.
572  *       To allow enforcement of this, dbu must already be zeroed on entry.
573  */
574 /*ARGSUSED*/
575 inline void
576 dmu_buf_init_user(dmu_buf_user_t *dbu, dmu_buf_evict_func_t *evict_func_sync,
577     dmu_buf_evict_func_t *evict_func_async, dmu_buf_t **clear_on_evict_dbufp)
578 {
579 	ASSERT(dbu->dbu_evict_func_sync == NULL);
580 	ASSERT(dbu->dbu_evict_func_async == NULL);
581 
582 	/* must have at least one evict func */
583 	IMPLY(evict_func_sync == NULL, evict_func_async != NULL);
584 	dbu->dbu_evict_func_sync = evict_func_sync;
585 	dbu->dbu_evict_func_async = evict_func_async;
586 #ifdef ZFS_DEBUG
587 	dbu->dbu_clear_on_evict_dbufp = clear_on_evict_dbufp;
588 #endif
589 }
590 
591 /*
592  * Attach user data to a dbuf and mark it for normal (when the dbuf's
593  * data is cleared or its reference count goes to zero) eviction processing.
594  *
595  * Returns NULL on success, or the existing user if another user currently
596  * owns the buffer.
597  */
598 void *dmu_buf_set_user(dmu_buf_t *db, dmu_buf_user_t *user);
599 
600 /*
601  * Attach user data to a dbuf and mark it for immediate (its dirty and
602  * reference counts are equal) eviction processing.
603  *
604  * Returns NULL on success, or the existing user if another user currently
605  * owns the buffer.
606  */
607 void *dmu_buf_set_user_ie(dmu_buf_t *db, dmu_buf_user_t *user);
608 
609 /*
610  * Replace the current user of a dbuf.
611  *
612  * If given the current user of a dbuf, replaces the dbuf's user with
613  * "new_user" and returns the user data pointer that was replaced.
614  * Otherwise returns the current, and unmodified, dbuf user pointer.
615  */
616 void *dmu_buf_replace_user(dmu_buf_t *db,
617     dmu_buf_user_t *old_user, dmu_buf_user_t *new_user);
618 
619 /*
620  * Remove the specified user data for a DMU buffer.
621  *
622  * Returns the user that was removed on success, or the current user if
623  * another user currently owns the buffer.
624  */
625 void *dmu_buf_remove_user(dmu_buf_t *db, dmu_buf_user_t *user);
626 
627 /*
628  * Returns the user data (dmu_buf_user_t *) associated with this dbuf.
629  */
630 void *dmu_buf_get_user(dmu_buf_t *db);
631 
632 objset_t *dmu_buf_get_objset(dmu_buf_t *db);
633 dnode_t *dmu_buf_dnode_enter(dmu_buf_t *db);
634 void dmu_buf_dnode_exit(dmu_buf_t *db);
635 
636 /* Block until any in-progress dmu buf user evictions complete. */
637 void dmu_buf_user_evict_wait(void);
638 
639 /*
640  * Returns the blkptr associated with this dbuf, or NULL if not set.
641  */
642 struct blkptr *dmu_buf_get_blkptr(dmu_buf_t *db);
643 
644 /*
645  * Indicate that you are going to modify the buffer's data (db_data).
646  *
647  * The transaction (tx) must be assigned to a txg (ie. you've called
648  * dmu_tx_assign()).  The buffer's object must be held in the tx
649  * (ie. you've called dmu_tx_hold_object(tx, db->db_object)).
650  */
651 void dmu_buf_will_dirty(dmu_buf_t *db, dmu_tx_t *tx);
652 
653 /*
654  * You must create a transaction, then hold the objects which you will
655  * (or might) modify as part of this transaction.  Then you must assign
656  * the transaction to a transaction group.  Once the transaction has
657  * been assigned, you can modify buffers which belong to held objects as
658  * part of this transaction.  You can't modify buffers before the
659  * transaction has been assigned; you can't modify buffers which don't
660  * belong to objects which this transaction holds; you can't hold
661  * objects once the transaction has been assigned.  You may hold an
662  * object which you are going to free (with dmu_object_free()), but you
663  * don't have to.
664  *
665  * You can abort the transaction before it has been assigned.
666  *
667  * Note that you may hold buffers (with dmu_buf_hold) at any time,
668  * regardless of transaction state.
669  */
670 
671 #define	DMU_NEW_OBJECT	(-1ULL)
672 #define	DMU_OBJECT_END	(-1ULL)
673 
674 dmu_tx_t *dmu_tx_create(objset_t *os);
675 void dmu_tx_hold_write(dmu_tx_t *tx, uint64_t object, uint64_t off, int len);
676 void dmu_tx_hold_write_by_dnode(dmu_tx_t *tx, dnode_t *dn, uint64_t off,
677     int len);
678 void dmu_tx_hold_free(dmu_tx_t *tx, uint64_t object, uint64_t off,
679     uint64_t len);
680 void dmu_tx_hold_free_by_dnode(dmu_tx_t *tx, dnode_t *dn, uint64_t off,
681     uint64_t len);
682 void dmu_tx_hold_remap_l1indirect(dmu_tx_t *tx, uint64_t object);
683 void dmu_tx_hold_zap(dmu_tx_t *tx, uint64_t object, int add, const char *name);
684 void dmu_tx_hold_zap_by_dnode(dmu_tx_t *tx, dnode_t *dn, int add,
685     const char *name);
686 void dmu_tx_hold_bonus(dmu_tx_t *tx, uint64_t object);
687 void dmu_tx_hold_bonus_by_dnode(dmu_tx_t *tx, dnode_t *dn);
688 void dmu_tx_hold_spill(dmu_tx_t *tx, uint64_t object);
689 void dmu_tx_hold_sa(dmu_tx_t *tx, struct sa_handle *hdl, boolean_t may_grow);
690 void dmu_tx_hold_sa_create(dmu_tx_t *tx, int total_size);
691 void dmu_tx_abort(dmu_tx_t *tx);
692 int dmu_tx_assign(dmu_tx_t *tx, enum txg_how txg_how);
693 void dmu_tx_wait(dmu_tx_t *tx);
694 void dmu_tx_commit(dmu_tx_t *tx);
695 void dmu_tx_mark_netfree(dmu_tx_t *tx);
696 
697 /*
698  * To register a commit callback, dmu_tx_callback_register() must be called.
699  *
700  * dcb_data is a pointer to caller private data that is passed on as a
701  * callback parameter. The caller is responsible for properly allocating and
702  * freeing it.
703  *
704  * When registering a callback, the transaction must be already created, but
705  * it cannot be committed or aborted. It can be assigned to a txg or not.
706  *
707  * The callback will be called after the transaction has been safely written
708  * to stable storage and will also be called if the dmu_tx is aborted.
709  * If there is any error which prevents the transaction from being committed to
710  * disk, the callback will be called with a value of error != 0.
711  */
712 typedef void dmu_tx_callback_func_t(void *dcb_data, int error);
713 
714 void dmu_tx_callback_register(dmu_tx_t *tx, dmu_tx_callback_func_t *dcb_func,
715     void *dcb_data);
716 
717 /*
718  * Free up the data blocks for a defined range of a file.  If size is
719  * -1, the range from offset to end-of-file is freed.
720  */
721 int dmu_free_range(objset_t *os, uint64_t object, uint64_t offset,
722 	uint64_t size, dmu_tx_t *tx);
723 int dmu_free_long_range(objset_t *os, uint64_t object, uint64_t offset,
724 	uint64_t size);
725 int dmu_free_long_object(objset_t *os, uint64_t object);
726 
727 /*
728  * Convenience functions.
729  *
730  * Canfail routines will return 0 on success, or an errno if there is a
731  * nonrecoverable I/O error.
732  */
733 #define	DMU_READ_PREFETCH	0 /* prefetch */
734 #define	DMU_READ_NO_PREFETCH	1 /* don't prefetch */
735 int dmu_read(objset_t *os, uint64_t object, uint64_t offset, uint64_t size,
736 	void *buf, uint32_t flags);
737 int dmu_read_by_dnode(dnode_t *dn, uint64_t offset, uint64_t size, void *buf,
738     uint32_t flags);
739 void dmu_write(objset_t *os, uint64_t object, uint64_t offset, uint64_t size,
740 	const void *buf, dmu_tx_t *tx);
741 void dmu_write_by_dnode(dnode_t *dn, uint64_t offset, uint64_t size,
742     const void *buf, dmu_tx_t *tx);
743 void dmu_prealloc(objset_t *os, uint64_t object, uint64_t offset, uint64_t size,
744 	dmu_tx_t *tx);
745 int dmu_read_uio(objset_t *os, uint64_t object, struct uio *uio, uint64_t size);
746 int dmu_read_uio_dbuf(dmu_buf_t *zdb, struct uio *uio, uint64_t size);
747 int dmu_write_uio(objset_t *os, uint64_t object, struct uio *uio, uint64_t size,
748     dmu_tx_t *tx);
749 int dmu_write_uio_dbuf(dmu_buf_t *zdb, struct uio *uio, uint64_t size,
750     dmu_tx_t *tx);
751 int dmu_write_pages(objset_t *os, uint64_t object, uint64_t offset,
752     uint64_t size, struct page *pp, dmu_tx_t *tx);
753 struct arc_buf *dmu_request_arcbuf(dmu_buf_t *handle, int size);
754 void dmu_return_arcbuf(struct arc_buf *buf);
755 void dmu_assign_arcbuf(dmu_buf_t *handle, uint64_t offset, struct arc_buf *buf,
756     dmu_tx_t *tx);
757 int dmu_xuio_init(struct xuio *uio, int niov);
758 void dmu_xuio_fini(struct xuio *uio);
759 int dmu_xuio_add(struct xuio *uio, struct arc_buf *abuf, offset_t off,
760     size_t n);
761 int dmu_xuio_cnt(struct xuio *uio);
762 struct arc_buf *dmu_xuio_arcbuf(struct xuio *uio, int i);
763 void dmu_xuio_clear(struct xuio *uio, int i);
764 void xuio_stat_wbuf_copied(void);
765 void xuio_stat_wbuf_nocopy(void);
766 
767 extern boolean_t zfs_prefetch_disable;
768 extern int zfs_max_recordsize;
769 
770 /*
771  * Asynchronously try to read in the data.
772  */
773 void dmu_prefetch(objset_t *os, uint64_t object, int64_t level, uint64_t offset,
774     uint64_t len, enum zio_priority pri);
775 
776 typedef struct dmu_object_info {
777 	/* All sizes are in bytes unless otherwise indicated. */
778 	uint32_t doi_data_block_size;
779 	uint32_t doi_metadata_block_size;
780 	dmu_object_type_t doi_type;
781 	dmu_object_type_t doi_bonus_type;
782 	uint64_t doi_bonus_size;
783 	uint8_t doi_indirection;		/* 2 = dnode->indirect->data */
784 	uint8_t doi_checksum;
785 	uint8_t doi_compress;
786 	uint8_t doi_nblkptr;
787 	uint8_t doi_pad[4];
788 	uint64_t doi_physical_blocks_512;	/* data + metadata, 512b blks */
789 	uint64_t doi_max_offset;
790 	uint64_t doi_fill_count;		/* number of non-empty blocks */
791 } dmu_object_info_t;
792 
793 typedef void arc_byteswap_func_t(void *buf, size_t size);
794 
795 typedef struct dmu_object_type_info {
796 	dmu_object_byteswap_t	ot_byteswap;
797 	boolean_t		ot_metadata;
798 	char			*ot_name;
799 } dmu_object_type_info_t;
800 
801 typedef struct dmu_object_byteswap_info {
802 	arc_byteswap_func_t	*ob_func;
803 	char			*ob_name;
804 } dmu_object_byteswap_info_t;
805 
806 extern const dmu_object_type_info_t dmu_ot[DMU_OT_NUMTYPES];
807 extern const dmu_object_byteswap_info_t dmu_ot_byteswap[DMU_BSWAP_NUMFUNCS];
808 
809 /*
810  * Get information on a DMU object.
811  *
812  * Return 0 on success or ENOENT if object is not allocated.
813  *
814  * If doi is NULL, just indicates whether the object exists.
815  */
816 int dmu_object_info(objset_t *os, uint64_t object, dmu_object_info_t *doi);
817 /* Like dmu_object_info, but faster if you have a held dnode in hand. */
818 void dmu_object_info_from_dnode(dnode_t *dn, dmu_object_info_t *doi);
819 /* Like dmu_object_info, but faster if you have a held dbuf in hand. */
820 void dmu_object_info_from_db(dmu_buf_t *db, dmu_object_info_t *doi);
821 /*
822  * Like dmu_object_info_from_db, but faster still when you only care about
823  * the size.  This is specifically optimized for zfs_getattr().
824  */
825 void dmu_object_size_from_db(dmu_buf_t *db, uint32_t *blksize,
826     u_longlong_t *nblk512);
827 
828 typedef struct dmu_objset_stats {
829 	uint64_t dds_num_clones; /* number of clones of this */
830 	uint64_t dds_creation_txg;
831 	uint64_t dds_guid;
832 	dmu_objset_type_t dds_type;
833 	uint8_t dds_is_snapshot;
834 	uint8_t dds_inconsistent;
835 	char dds_origin[ZFS_MAX_DATASET_NAME_LEN];
836 } dmu_objset_stats_t;
837 
838 /*
839  * Get stats on a dataset.
840  */
841 void dmu_objset_fast_stat(objset_t *os, dmu_objset_stats_t *stat);
842 
843 /*
844  * Add entries to the nvlist for all the objset's properties.  See
845  * zfs_prop_table[] and zfs(1m) for details on the properties.
846  */
847 void dmu_objset_stats(objset_t *os, struct nvlist *nv);
848 
849 /*
850  * Get the space usage statistics for statvfs().
851  *
852  * refdbytes is the amount of space "referenced" by this objset.
853  * availbytes is the amount of space available to this objset, taking
854  * into account quotas & reservations, assuming that no other objsets
855  * use the space first.  These values correspond to the 'referenced' and
856  * 'available' properties, described in the zfs(1m) manpage.
857  *
858  * usedobjs and availobjs are the number of objects currently allocated,
859  * and available.
860  */
861 void dmu_objset_space(objset_t *os, uint64_t *refdbytesp, uint64_t *availbytesp,
862     uint64_t *usedobjsp, uint64_t *availobjsp);
863 
864 /*
865  * The fsid_guid is a 56-bit ID that can change to avoid collisions.
866  * (Contrast with the ds_guid which is a 64-bit ID that will never
867  * change, so there is a small probability that it will collide.)
868  */
869 uint64_t dmu_objset_fsid_guid(objset_t *os);
870 
871 /*
872  * Get the [cm]time for an objset's snapshot dir
873  */
874 timestruc_t dmu_objset_snap_cmtime(objset_t *os);
875 
876 int dmu_objset_is_snapshot(objset_t *os);
877 
878 extern struct spa *dmu_objset_spa(objset_t *os);
879 extern struct zilog *dmu_objset_zil(objset_t *os);
880 extern struct dsl_pool *dmu_objset_pool(objset_t *os);
881 extern struct dsl_dataset *dmu_objset_ds(objset_t *os);
882 extern void dmu_objset_name(objset_t *os, char *buf);
883 extern dmu_objset_type_t dmu_objset_type(objset_t *os);
884 extern uint64_t dmu_objset_id(objset_t *os);
885 extern zfs_sync_type_t dmu_objset_syncprop(objset_t *os);
886 extern zfs_logbias_op_t dmu_objset_logbias(objset_t *os);
887 extern int dmu_snapshot_list_next(objset_t *os, int namelen, char *name,
888     uint64_t *id, uint64_t *offp, boolean_t *case_conflict);
889 extern int dmu_snapshot_realname(objset_t *os, char *name, char *real,
890     int maxlen, boolean_t *conflict);
891 extern int dmu_dir_list_next(objset_t *os, int namelen, char *name,
892     uint64_t *idp, uint64_t *offp);
893 
894 typedef int objset_used_cb_t(dmu_object_type_t bonustype,
895     void *bonus, uint64_t *userp, uint64_t *groupp);
896 extern void dmu_objset_register_type(dmu_objset_type_t ost,
897     objset_used_cb_t *cb);
898 extern void dmu_objset_set_user(objset_t *os, void *user_ptr);
899 extern void *dmu_objset_get_user(objset_t *os);
900 
901 /*
902  * Return the txg number for the given assigned transaction.
903  */
904 uint64_t dmu_tx_get_txg(dmu_tx_t *tx);
905 
906 /*
907  * Synchronous write.
908  * If a parent zio is provided this function initiates a write on the
909  * provided buffer as a child of the parent zio.
910  * In the absence of a parent zio, the write is completed synchronously.
911  * At write completion, blk is filled with the bp of the written block.
912  * Note that while the data covered by this function will be on stable
913  * storage when the write completes this new data does not become a
914  * permanent part of the file until the associated transaction commits.
915  */
916 
917 /*
918  * {zfs,zvol,ztest}_get_done() args
919  */
920 typedef struct zgd {
921 	struct lwb	*zgd_lwb;
922 	struct blkptr	*zgd_bp;
923 	dmu_buf_t	*zgd_db;
924 	struct rl	*zgd_rl;
925 	void		*zgd_private;
926 } zgd_t;
927 
928 typedef void dmu_sync_cb_t(zgd_t *arg, int error);
929 int dmu_sync(struct zio *zio, uint64_t txg, dmu_sync_cb_t *done, zgd_t *zgd);
930 
931 /*
932  * Find the next hole or data block in file starting at *off
933  * Return found offset in *off. Return ESRCH for end of file.
934  */
935 int dmu_offset_next(objset_t *os, uint64_t object, boolean_t hole,
936     uint64_t *off);
937 
938 /*
939  * Check if a DMU object has any dirty blocks. If so, sync out
940  * all pending transaction groups. Otherwise, this function
941  * does not alter DMU state. This could be improved to only sync
942  * out the necessary transaction groups for this particular
943  * object.
944  */
945 int dmu_object_wait_synced(objset_t *os, uint64_t object);
946 
947 /*
948  * Initial setup and final teardown.
949  */
950 extern void dmu_init(void);
951 extern void dmu_fini(void);
952 
953 typedef void (*dmu_traverse_cb_t)(objset_t *os, void *arg, struct blkptr *bp,
954     uint64_t object, uint64_t offset, int len);
955 void dmu_traverse_objset(objset_t *os, uint64_t txg_start,
956     dmu_traverse_cb_t cb, void *arg);
957 
958 int dmu_diff(const char *tosnap_name, const char *fromsnap_name,
959     struct vnode *vp, offset_t *offp);
960 
961 /* CRC64 table */
962 #define	ZFS_CRC64_POLY	0xC96C5795D7870F42ULL	/* ECMA-182, reflected form */
963 extern uint64_t zfs_crc64_table[256];
964 
965 extern int zfs_mdcomp_disable;
966 
967 #ifdef	__cplusplus
968 }
969 #endif
970 
971 #endif	/* _SYS_DMU_H */
972