xref: /illumos-gate/usr/src/uts/common/fs/zfs/sys/dmu.h (revision 54811da5)
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 struct locked_range;
79 
80 typedef struct objset objset_t;
81 typedef struct dmu_tx dmu_tx_t;
82 typedef struct dsl_dir dsl_dir_t;
83 typedef struct dnode dnode_t;
84 
85 typedef enum dmu_object_byteswap {
86 	DMU_BSWAP_UINT8,
87 	DMU_BSWAP_UINT16,
88 	DMU_BSWAP_UINT32,
89 	DMU_BSWAP_UINT64,
90 	DMU_BSWAP_ZAP,
91 	DMU_BSWAP_DNODE,
92 	DMU_BSWAP_OBJSET,
93 	DMU_BSWAP_ZNODE,
94 	DMU_BSWAP_OLDACL,
95 	DMU_BSWAP_ACL,
96 	/*
97 	 * Allocating a new byteswap type number makes the on-disk format
98 	 * incompatible with any other format that uses the same number.
99 	 *
100 	 * Data can usually be structured to work with one of the
101 	 * DMU_BSWAP_UINT* or DMU_BSWAP_ZAP types.
102 	 */
103 	DMU_BSWAP_NUMFUNCS
104 } dmu_object_byteswap_t;
105 
106 #define	DMU_OT_NEWTYPE 0x80
107 #define	DMU_OT_METADATA 0x40
108 #define	DMU_OT_BYTESWAP_MASK 0x3f
109 
110 /*
111  * Defines a uint8_t object type. Object types specify if the data
112  * in the object is metadata (boolean) and how to byteswap the data
113  * (dmu_object_byteswap_t). All of the types created by this method
114  * are cached in the dbuf metadata cache.
115  */
116 #define	DMU_OT(byteswap, metadata) \
117 	(DMU_OT_NEWTYPE | \
118 	((metadata) ? DMU_OT_METADATA : 0) | \
119 	((byteswap) & DMU_OT_BYTESWAP_MASK))
120 
121 #define	DMU_OT_IS_VALID(ot) (((ot) & DMU_OT_NEWTYPE) ? \
122 	((ot) & DMU_OT_BYTESWAP_MASK) < DMU_BSWAP_NUMFUNCS : \
123 	(ot) < DMU_OT_NUMTYPES)
124 
125 #define	DMU_OT_IS_METADATA(ot) (((ot) & DMU_OT_NEWTYPE) ? \
126 	((ot) & DMU_OT_METADATA) : \
127 	dmu_ot[(ot)].ot_metadata)
128 
129 #define	DMU_OT_IS_METADATA_CACHED(ot) (((ot) & DMU_OT_NEWTYPE) ? \
130 	B_TRUE : dmu_ot[(ot)].ot_dbuf_metadata_cache)
131 
132 /*
133  * These object types use bp_fill != 1 for their L0 bp's. Therefore they can't
134  * have their data embedded (i.e. use a BP_IS_EMBEDDED() bp), because bp_fill
135  * is repurposed for embedded BPs.
136  */
137 #define	DMU_OT_HAS_FILL(ot) \
138 	((ot) == DMU_OT_DNODE || (ot) == DMU_OT_OBJSET)
139 
140 #define	DMU_OT_BYTESWAP(ot) (((ot) & DMU_OT_NEWTYPE) ? \
141 	((ot) & DMU_OT_BYTESWAP_MASK) : \
142 	dmu_ot[(ot)].ot_byteswap)
143 
144 typedef enum dmu_object_type {
145 	DMU_OT_NONE,
146 	/* general: */
147 	DMU_OT_OBJECT_DIRECTORY,	/* ZAP */
148 	DMU_OT_OBJECT_ARRAY,		/* UINT64 */
149 	DMU_OT_PACKED_NVLIST,		/* UINT8 (XDR by nvlist_pack/unpack) */
150 	DMU_OT_PACKED_NVLIST_SIZE,	/* UINT64 */
151 	DMU_OT_BPOBJ,			/* UINT64 */
152 	DMU_OT_BPOBJ_HDR,		/* UINT64 */
153 	/* spa: */
154 	DMU_OT_SPACE_MAP_HEADER,	/* UINT64 */
155 	DMU_OT_SPACE_MAP,		/* UINT64 */
156 	/* zil: */
157 	DMU_OT_INTENT_LOG,		/* UINT64 */
158 	/* dmu: */
159 	DMU_OT_DNODE,			/* DNODE */
160 	DMU_OT_OBJSET,			/* OBJSET */
161 	/* dsl: */
162 	DMU_OT_DSL_DIR,			/* UINT64 */
163 	DMU_OT_DSL_DIR_CHILD_MAP,	/* ZAP */
164 	DMU_OT_DSL_DS_SNAP_MAP,		/* ZAP */
165 	DMU_OT_DSL_PROPS,		/* ZAP */
166 	DMU_OT_DSL_DATASET,		/* UINT64 */
167 	/* zpl: */
168 	DMU_OT_ZNODE,			/* ZNODE */
169 	DMU_OT_OLDACL,			/* Old ACL */
170 	DMU_OT_PLAIN_FILE_CONTENTS,	/* UINT8 */
171 	DMU_OT_DIRECTORY_CONTENTS,	/* ZAP */
172 	DMU_OT_MASTER_NODE,		/* ZAP */
173 	DMU_OT_UNLINKED_SET,		/* ZAP */
174 	/* zvol: */
175 	DMU_OT_ZVOL,			/* UINT8 */
176 	DMU_OT_ZVOL_PROP,		/* ZAP */
177 	/* other; for testing only! */
178 	DMU_OT_PLAIN_OTHER,		/* UINT8 */
179 	DMU_OT_UINT64_OTHER,		/* UINT64 */
180 	DMU_OT_ZAP_OTHER,		/* ZAP */
181 	/* new object types: */
182 	DMU_OT_ERROR_LOG,		/* ZAP */
183 	DMU_OT_SPA_HISTORY,		/* UINT8 */
184 	DMU_OT_SPA_HISTORY_OFFSETS,	/* spa_his_phys_t */
185 	DMU_OT_POOL_PROPS,		/* ZAP */
186 	DMU_OT_DSL_PERMS,		/* ZAP */
187 	DMU_OT_ACL,			/* ACL */
188 	DMU_OT_SYSACL,			/* SYSACL */
189 	DMU_OT_FUID,			/* FUID table (Packed NVLIST UINT8) */
190 	DMU_OT_FUID_SIZE,		/* FUID table size UINT64 */
191 	DMU_OT_NEXT_CLONES,		/* ZAP */
192 	DMU_OT_SCAN_QUEUE,		/* ZAP */
193 	DMU_OT_USERGROUP_USED,		/* ZAP */
194 	DMU_OT_USERGROUP_QUOTA,		/* ZAP */
195 	DMU_OT_USERREFS,		/* ZAP */
196 	DMU_OT_DDT_ZAP,			/* ZAP */
197 	DMU_OT_DDT_STATS,		/* ZAP */
198 	DMU_OT_SA,			/* System attr */
199 	DMU_OT_SA_MASTER_NODE,		/* ZAP */
200 	DMU_OT_SA_ATTR_REGISTRATION,	/* ZAP */
201 	DMU_OT_SA_ATTR_LAYOUTS,		/* ZAP */
202 	DMU_OT_SCAN_XLATE,		/* ZAP */
203 	DMU_OT_DEDUP,			/* fake dedup BP from ddt_bp_create() */
204 	DMU_OT_DEADLIST,		/* ZAP */
205 	DMU_OT_DEADLIST_HDR,		/* UINT64 */
206 	DMU_OT_DSL_CLONES,		/* ZAP */
207 	DMU_OT_BPOBJ_SUBOBJ,		/* UINT64 */
208 	/*
209 	 * Do not allocate new object types here. Doing so makes the on-disk
210 	 * format incompatible with any other format that uses the same object
211 	 * type number.
212 	 *
213 	 * When creating an object which does not have one of the above types
214 	 * use the DMU_OTN_* type with the correct byteswap and metadata
215 	 * values.
216 	 *
217 	 * The DMU_OTN_* types do not have entries in the dmu_ot table,
218 	 * use the DMU_OT_IS_METDATA() and DMU_OT_BYTESWAP() macros instead
219 	 * of indexing into dmu_ot directly (this works for both DMU_OT_* types
220 	 * and DMU_OTN_* types).
221 	 */
222 	DMU_OT_NUMTYPES,
223 
224 	/*
225 	 * Names for valid types declared with DMU_OT().
226 	 */
227 	DMU_OTN_UINT8_DATA = DMU_OT(DMU_BSWAP_UINT8, B_FALSE),
228 	DMU_OTN_UINT8_METADATA = DMU_OT(DMU_BSWAP_UINT8, B_TRUE),
229 	DMU_OTN_UINT16_DATA = DMU_OT(DMU_BSWAP_UINT16, B_FALSE),
230 	DMU_OTN_UINT16_METADATA = DMU_OT(DMU_BSWAP_UINT16, B_TRUE),
231 	DMU_OTN_UINT32_DATA = DMU_OT(DMU_BSWAP_UINT32, B_FALSE),
232 	DMU_OTN_UINT32_METADATA = DMU_OT(DMU_BSWAP_UINT32, B_TRUE),
233 	DMU_OTN_UINT64_DATA = DMU_OT(DMU_BSWAP_UINT64, B_FALSE),
234 	DMU_OTN_UINT64_METADATA = DMU_OT(DMU_BSWAP_UINT64, B_TRUE),
235 	DMU_OTN_ZAP_DATA = DMU_OT(DMU_BSWAP_ZAP, B_FALSE),
236 	DMU_OTN_ZAP_METADATA = DMU_OT(DMU_BSWAP_ZAP, B_TRUE),
237 } dmu_object_type_t;
238 
239 /*
240  * These flags are intended to be used to specify the "txg_how"
241  * parameter when calling the dmu_tx_assign() function. See the comment
242  * above dmu_tx_assign() for more details on the meaning of these flags.
243  */
244 #define	TXG_NOWAIT	(0ULL)
245 #define	TXG_WAIT	(1ULL<<0)
246 #define	TXG_NOTHROTTLE	(1ULL<<1)
247 
248 void byteswap_uint64_array(void *buf, size_t size);
249 void byteswap_uint32_array(void *buf, size_t size);
250 void byteswap_uint16_array(void *buf, size_t size);
251 void byteswap_uint8_array(void *buf, size_t size);
252 void zap_byteswap(void *buf, size_t size);
253 void zfs_oldacl_byteswap(void *buf, size_t size);
254 void zfs_acl_byteswap(void *buf, size_t size);
255 void zfs_znode_byteswap(void *buf, size_t size);
256 
257 #define	DS_FIND_SNAPSHOTS	(1<<0)
258 #define	DS_FIND_CHILDREN	(1<<1)
259 #define	DS_FIND_SERIALIZE	(1<<2)
260 
261 /*
262  * The maximum number of bytes that can be accessed as part of one
263  * operation, including metadata.
264  */
265 #define	DMU_MAX_ACCESS (32 * 1024 * 1024) /* 32MB */
266 #define	DMU_MAX_DELETEBLKCNT (20480) /* ~5MB of indirect blocks */
267 
268 #define	DMU_USERUSED_OBJECT	(-1ULL)
269 #define	DMU_GROUPUSED_OBJECT	(-2ULL)
270 
271 /*
272  * artificial blkids for bonus buffer and spill blocks
273  */
274 #define	DMU_BONUS_BLKID		(-1ULL)
275 #define	DMU_SPILL_BLKID		(-2ULL)
276 /*
277  * Public routines to create, destroy, open, and close objsets.
278  */
279 int dmu_objset_hold(const char *name, void *tag, objset_t **osp);
280 int dmu_objset_own(const char *name, dmu_objset_type_t type,
281     boolean_t readonly, void *tag, objset_t **osp);
282 void dmu_objset_rele(objset_t *os, void *tag);
283 void dmu_objset_disown(objset_t *os, void *tag);
284 int dmu_objset_open_ds(struct dsl_dataset *ds, objset_t **osp);
285 
286 void dmu_objset_evict_dbufs(objset_t *os);
287 int dmu_objset_create(const char *name, dmu_objset_type_t type, uint64_t flags,
288     void (*func)(objset_t *os, void *arg, cred_t *cr, dmu_tx_t *tx), void *arg);
289 int dmu_objset_clone(const char *name, const char *origin);
290 int dsl_destroy_snapshots_nvl(struct nvlist *snaps, boolean_t defer,
291     struct nvlist *errlist);
292 int dmu_objset_snapshot_one(const char *fsname, const char *snapname);
293 int dmu_objset_snapshot_tmp(const char *, const char *, int);
294 int dmu_objset_find(char *name, int func(const char *, void *), void *arg,
295     int flags);
296 void dmu_objset_byteswap(void *buf, size_t size);
297 int dsl_dataset_rename_snapshot(const char *fsname,
298     const char *oldsnapname, const char *newsnapname, boolean_t recursive);
299 int dmu_objset_remap_indirects(const char *fsname);
300 
301 typedef struct dmu_buf {
302 	uint64_t db_object;		/* object that this buffer is part of */
303 	uint64_t db_offset;		/* byte offset in this object */
304 	uint64_t db_size;		/* size of buffer in bytes */
305 	void *db_data;			/* data in buffer */
306 } dmu_buf_t;
307 
308 /*
309  * The names of zap entries in the DIRECTORY_OBJECT of the MOS.
310  */
311 #define	DMU_POOL_DIRECTORY_OBJECT	1
312 #define	DMU_POOL_CONFIG			"config"
313 #define	DMU_POOL_FEATURES_FOR_WRITE	"features_for_write"
314 #define	DMU_POOL_FEATURES_FOR_READ	"features_for_read"
315 #define	DMU_POOL_FEATURE_DESCRIPTIONS	"feature_descriptions"
316 #define	DMU_POOL_FEATURE_ENABLED_TXG	"feature_enabled_txg"
317 #define	DMU_POOL_ROOT_DATASET		"root_dataset"
318 #define	DMU_POOL_SYNC_BPOBJ		"sync_bplist"
319 #define	DMU_POOL_ERRLOG_SCRUB		"errlog_scrub"
320 #define	DMU_POOL_ERRLOG_LAST		"errlog_last"
321 #define	DMU_POOL_SPARES			"spares"
322 #define	DMU_POOL_DEFLATE		"deflate"
323 #define	DMU_POOL_HISTORY		"history"
324 #define	DMU_POOL_PROPS			"pool_props"
325 #define	DMU_POOL_L2CACHE		"l2cache"
326 #define	DMU_POOL_TMP_USERREFS		"tmp_userrefs"
327 #define	DMU_POOL_DDT			"DDT-%s-%s-%s"
328 #define	DMU_POOL_DDT_STATS		"DDT-statistics"
329 #define	DMU_POOL_CREATION_VERSION	"creation_version"
330 #define	DMU_POOL_SCAN			"scan"
331 #define	DMU_POOL_FREE_BPOBJ		"free_bpobj"
332 #define	DMU_POOL_BPTREE_OBJ		"bptree_obj"
333 #define	DMU_POOL_EMPTY_BPOBJ		"empty_bpobj"
334 #define	DMU_POOL_CHECKSUM_SALT		"org.illumos:checksum_salt"
335 #define	DMU_POOL_VDEV_ZAP_MAP		"com.delphix:vdev_zap_map"
336 #define	DMU_POOL_REMOVING		"com.delphix:removing"
337 #define	DMU_POOL_OBSOLETE_BPOBJ		"com.delphix:obsolete_bpobj"
338 #define	DMU_POOL_CONDENSING_INDIRECT	"com.delphix:condensing_indirect"
339 #define	DMU_POOL_ZPOOL_CHECKPOINT	"com.delphix:zpool_checkpoint"
340 
341 /*
342  * Allocate an object from this objset.  The range of object numbers
343  * available is (0, DN_MAX_OBJECT).  Object 0 is the meta-dnode.
344  *
345  * The transaction must be assigned to a txg.  The newly allocated
346  * object will be "held" in the transaction (ie. you can modify the
347  * newly allocated object in this transaction).
348  *
349  * dmu_object_alloc() chooses an object and returns it in *objectp.
350  *
351  * dmu_object_claim() allocates a specific object number.  If that
352  * number is already allocated, it fails and returns EEXIST.
353  *
354  * Return 0 on success, or ENOSPC or EEXIST as specified above.
355  */
356 uint64_t dmu_object_alloc(objset_t *os, dmu_object_type_t ot,
357     int blocksize, dmu_object_type_t bonus_type, int bonus_len, dmu_tx_t *tx);
358 uint64_t dmu_object_alloc_ibs(objset_t *os, dmu_object_type_t ot, int blocksize,
359     int indirect_blockshift,
360     dmu_object_type_t bonustype, int bonuslen, dmu_tx_t *tx);
361 uint64_t dmu_object_alloc_dnsize(objset_t *os, dmu_object_type_t ot,
362     int blocksize, dmu_object_type_t bonus_type, int bonus_len,
363     int dnodesize, dmu_tx_t *tx);
364 int dmu_object_claim_dnsize(objset_t *os, uint64_t object, dmu_object_type_t ot,
365     int blocksize, dmu_object_type_t bonus_type, int bonus_len,
366     int dnodesize, dmu_tx_t *tx);
367 int dmu_object_reclaim_dnsize(objset_t *os, uint64_t object,
368     dmu_object_type_t ot, int blocksize, dmu_object_type_t bonustype,
369     int bonuslen, int dnodesize, dmu_tx_t *txp);
370 int dmu_object_claim(objset_t *os, uint64_t object, dmu_object_type_t ot,
371     int blocksize, dmu_object_type_t bonus_type, int bonus_len, dmu_tx_t *tx);
372 int dmu_object_reclaim(objset_t *os, uint64_t object, dmu_object_type_t ot,
373     int blocksize, dmu_object_type_t bonustype, int bonuslen, dmu_tx_t *txp);
374 
375 /*
376  * Free an object from this objset.
377  *
378  * The object's data will be freed as well (ie. you don't need to call
379  * dmu_free(object, 0, -1, tx)).
380  *
381  * The object need not be held in the transaction.
382  *
383  * If there are any holds on this object's buffers (via dmu_buf_hold()),
384  * or tx holds on the object (via dmu_tx_hold_object()), you can not
385  * free it; it fails and returns EBUSY.
386  *
387  * If the object is not allocated, it fails and returns ENOENT.
388  *
389  * Return 0 on success, or EBUSY or ENOENT as specified above.
390  */
391 int dmu_object_free(objset_t *os, uint64_t object, dmu_tx_t *tx);
392 
393 /*
394  * Find the next allocated or free object.
395  *
396  * The objectp parameter is in-out.  It will be updated to be the next
397  * object which is allocated.  Ignore objects which have not been
398  * modified since txg.
399  *
400  * XXX Can only be called on a objset with no dirty data.
401  *
402  * Returns 0 on success, or ENOENT if there are no more objects.
403  */
404 int dmu_object_next(objset_t *os, uint64_t *objectp,
405     boolean_t hole, uint64_t txg);
406 
407 /*
408  * Set the data blocksize for an object.
409  *
410  * The object cannot have any blocks allcated beyond the first.  If
411  * the first block is allocated already, the new size must be greater
412  * than the current block size.  If these conditions are not met,
413  * ENOTSUP will be returned.
414  *
415  * Returns 0 on success, or EBUSY if there are any holds on the object
416  * contents, or ENOTSUP as described above.
417  */
418 int dmu_object_set_blocksize(objset_t *os, uint64_t object, uint64_t size,
419     int ibs, dmu_tx_t *tx);
420 
421 /*
422  * Set the checksum property on a dnode.  The new checksum algorithm will
423  * apply to all newly written blocks; existing blocks will not be affected.
424  */
425 void dmu_object_set_checksum(objset_t *os, uint64_t object, uint8_t checksum,
426     dmu_tx_t *tx);
427 
428 /*
429  * Set the compress property on a dnode.  The new compression algorithm will
430  * apply to all newly written blocks; existing blocks will not be affected.
431  */
432 void dmu_object_set_compress(objset_t *os, uint64_t object, uint8_t compress,
433     dmu_tx_t *tx);
434 
435 int dmu_object_remap_indirects(objset_t *os, uint64_t object, uint64_t txg);
436 
437 void
438 dmu_write_embedded(objset_t *os, uint64_t object, uint64_t offset,
439     void *data, uint8_t etype, uint8_t comp, int uncompressed_size,
440     int compressed_size, int byteorder, dmu_tx_t *tx);
441 
442 /*
443  * Decide how to write a block: checksum, compression, number of copies, etc.
444  */
445 #define	WP_NOFILL	0x1
446 #define	WP_DMU_SYNC	0x2
447 #define	WP_SPILL	0x4
448 
449 void dmu_write_policy(objset_t *os, dnode_t *dn, int level, int wp,
450     struct zio_prop *zp);
451 /*
452  * The bonus data is accessed more or less like a regular buffer.
453  * You must dmu_bonus_hold() to get the buffer, which will give you a
454  * dmu_buf_t with db_offset==-1ULL, and db_size = the size of the bonus
455  * data.  As with any normal buffer, you must call dmu_buf_will_dirty()
456  * before modifying it, and the
457  * object must be held in an assigned transaction before calling
458  * dmu_buf_will_dirty.  You may use dmu_buf_set_user() on the bonus
459  * buffer as well.  You must release your hold with dmu_buf_rele().
460  *
461  * Returns ENOENT, EIO, or 0.
462  */
463 int dmu_bonus_hold(objset_t *os, uint64_t object, void *tag, dmu_buf_t **);
464 int dmu_bonus_max(void);
465 int dmu_set_bonus(dmu_buf_t *, int, dmu_tx_t *);
466 int dmu_set_bonustype(dmu_buf_t *, dmu_object_type_t, dmu_tx_t *);
467 dmu_object_type_t dmu_get_bonustype(dmu_buf_t *);
468 int dmu_rm_spill(objset_t *, uint64_t, dmu_tx_t *);
469 
470 /*
471  * Special spill buffer support used by "SA" framework
472  */
473 
474 int dmu_spill_hold_by_bonus(dmu_buf_t *bonus, void *tag, dmu_buf_t **dbp);
475 int dmu_spill_hold_by_dnode(dnode_t *dn, uint32_t flags,
476     void *tag, dmu_buf_t **dbp);
477 int dmu_spill_hold_existing(dmu_buf_t *bonus, void *tag, dmu_buf_t **dbp);
478 
479 /*
480  * Obtain the DMU buffer from the specified object which contains the
481  * specified offset.  dmu_buf_hold() puts a "hold" on the buffer, so
482  * that it will remain in memory.  You must release the hold with
483  * dmu_buf_rele().  You musn't access the dmu_buf_t after releasing your
484  * hold.  You must have a hold on any dmu_buf_t* you pass to the DMU.
485  *
486  * You must call dmu_buf_read, dmu_buf_will_dirty, or dmu_buf_will_fill
487  * on the returned buffer before reading or writing the buffer's
488  * db_data.  The comments for those routines describe what particular
489  * operations are valid after calling them.
490  *
491  * The object number must be a valid, allocated object number.
492  */
493 int dmu_buf_hold(objset_t *os, uint64_t object, uint64_t offset,
494     void *tag, dmu_buf_t **, int flags);
495 int dmu_buf_hold_by_dnode(dnode_t *dn, uint64_t offset,
496     void *tag, dmu_buf_t **dbp, int flags);
497 
498 /*
499  * Add a reference to a dmu buffer that has already been held via
500  * dmu_buf_hold() in the current context.
501  */
502 void dmu_buf_add_ref(dmu_buf_t *db, void* tag);
503 
504 /*
505  * Attempt to add a reference to a dmu buffer that is in an unknown state,
506  * using a pointer that may have been invalidated by eviction processing.
507  * The request will succeed if the passed in dbuf still represents the
508  * same os/object/blkid, is ineligible for eviction, and has at least
509  * one hold by a user other than the syncer.
510  */
511 boolean_t dmu_buf_try_add_ref(dmu_buf_t *, objset_t *os, uint64_t object,
512     uint64_t blkid, void *tag);
513 
514 void dmu_buf_rele(dmu_buf_t *db, void *tag);
515 uint64_t dmu_buf_refcount(dmu_buf_t *db);
516 
517 /*
518  * dmu_buf_hold_array holds the DMU buffers which contain all bytes in a
519  * range of an object.  A pointer to an array of dmu_buf_t*'s is
520  * returned (in *dbpp).
521  *
522  * dmu_buf_rele_array releases the hold on an array of dmu_buf_t*'s, and
523  * frees the array.  The hold on the array of buffers MUST be released
524  * with dmu_buf_rele_array.  You can NOT release the hold on each buffer
525  * individually with dmu_buf_rele.
526  */
527 int dmu_buf_hold_array_by_bonus(dmu_buf_t *db, uint64_t offset,
528     uint64_t length, boolean_t read, void *tag,
529     int *numbufsp, dmu_buf_t ***dbpp);
530 int dmu_buf_hold_array_by_dnode(dnode_t *dn, uint64_t offset, uint64_t length,
531     boolean_t read, void *tag, int *numbufsp, dmu_buf_t ***dbpp,
532     uint32_t flags);
533 void dmu_buf_rele_array(dmu_buf_t **, int numbufs, void *tag);
534 
535 typedef void dmu_buf_evict_func_t(void *user_ptr);
536 
537 /*
538  * A DMU buffer user object may be associated with a dbuf for the
539  * duration of its lifetime.  This allows the user of a dbuf (client)
540  * to attach private data to a dbuf (e.g. in-core only data such as a
541  * dnode_children_t, zap_t, or zap_leaf_t) and be optionally notified
542  * when that dbuf has been evicted.  Clients typically respond to the
543  * eviction notification by freeing their private data, thus ensuring
544  * the same lifetime for both dbuf and private data.
545  *
546  * The mapping from a dmu_buf_user_t to any client private data is the
547  * client's responsibility.  All current consumers of the API with private
548  * data embed a dmu_buf_user_t as the first member of the structure for
549  * their private data.  This allows conversions between the two types
550  * with a simple cast.  Since the DMU buf user API never needs access
551  * to the private data, other strategies can be employed if necessary
552  * or convenient for the client (e.g. using __containerof() to do the
553  * conversion for private data that cannot have the dmu_buf_user_t as
554  * its first member).
555  *
556  * Eviction callbacks are executed without the dbuf mutex held or any
557  * other type of mechanism to guarantee that the dbuf is still available.
558  * For this reason, users must assume the dbuf has already been freed
559  * and not reference the dbuf from the callback context.
560  *
561  * Users requesting "immediate eviction" are notified as soon as the dbuf
562  * is only referenced by dirty records (dirties == holds).  Otherwise the
563  * notification occurs after eviction processing for the dbuf begins.
564  */
565 typedef struct dmu_buf_user {
566 	/*
567 	 * Asynchronous user eviction callback state.
568 	 */
569 	taskq_ent_t	dbu_tqent;
570 
571 	/*
572 	 * This instance's eviction function pointers.
573 	 *
574 	 * dbu_evict_func_sync is called synchronously and then
575 	 * dbu_evict_func_async is executed asynchronously on a taskq.
576 	 */
577 	dmu_buf_evict_func_t *dbu_evict_func_sync;
578 	dmu_buf_evict_func_t *dbu_evict_func_async;
579 #ifdef ZFS_DEBUG
580 	/*
581 	 * Pointer to user's dbuf pointer.  NULL for clients that do
582 	 * not associate a dbuf with their user data.
583 	 *
584 	 * The dbuf pointer is cleared upon eviction so as to catch
585 	 * use-after-evict bugs in clients.
586 	 */
587 	dmu_buf_t **dbu_clear_on_evict_dbufp;
588 #endif
589 } dmu_buf_user_t;
590 
591 /*
592  * Initialize the given dmu_buf_user_t instance with the eviction function
593  * evict_func, to be called when the user is evicted.
594  *
595  * NOTE: This function should only be called once on a given dmu_buf_user_t.
596  *       To allow enforcement of this, dbu must already be zeroed on entry.
597  */
598 /*ARGSUSED*/
599 inline void
600 dmu_buf_init_user(dmu_buf_user_t *dbu, dmu_buf_evict_func_t *evict_func_sync,
601     dmu_buf_evict_func_t *evict_func_async, dmu_buf_t **clear_on_evict_dbufp)
602 {
603 	ASSERT(dbu->dbu_evict_func_sync == NULL);
604 	ASSERT(dbu->dbu_evict_func_async == NULL);
605 
606 	/* must have at least one evict func */
607 	IMPLY(evict_func_sync == NULL, evict_func_async != NULL);
608 	dbu->dbu_evict_func_sync = evict_func_sync;
609 	dbu->dbu_evict_func_async = evict_func_async;
610 #ifdef ZFS_DEBUG
611 	dbu->dbu_clear_on_evict_dbufp = clear_on_evict_dbufp;
612 #endif
613 }
614 
615 /*
616  * Attach user data to a dbuf and mark it for normal (when the dbuf's
617  * data is cleared or its reference count goes to zero) eviction processing.
618  *
619  * Returns NULL on success, or the existing user if another user currently
620  * owns the buffer.
621  */
622 void *dmu_buf_set_user(dmu_buf_t *db, dmu_buf_user_t *user);
623 
624 /*
625  * Attach user data to a dbuf and mark it for immediate (its dirty and
626  * reference counts are equal) eviction processing.
627  *
628  * Returns NULL on success, or the existing user if another user currently
629  * owns the buffer.
630  */
631 void *dmu_buf_set_user_ie(dmu_buf_t *db, dmu_buf_user_t *user);
632 
633 /*
634  * Replace the current user of a dbuf.
635  *
636  * If given the current user of a dbuf, replaces the dbuf's user with
637  * "new_user" and returns the user data pointer that was replaced.
638  * Otherwise returns the current, and unmodified, dbuf user pointer.
639  */
640 void *dmu_buf_replace_user(dmu_buf_t *db,
641     dmu_buf_user_t *old_user, dmu_buf_user_t *new_user);
642 
643 /*
644  * Remove the specified user data for a DMU buffer.
645  *
646  * Returns the user that was removed on success, or the current user if
647  * another user currently owns the buffer.
648  */
649 void *dmu_buf_remove_user(dmu_buf_t *db, dmu_buf_user_t *user);
650 
651 /*
652  * Returns the user data (dmu_buf_user_t *) associated with this dbuf.
653  */
654 void *dmu_buf_get_user(dmu_buf_t *db);
655 
656 objset_t *dmu_buf_get_objset(dmu_buf_t *db);
657 dnode_t *dmu_buf_dnode_enter(dmu_buf_t *db);
658 void dmu_buf_dnode_exit(dmu_buf_t *db);
659 
660 /* Block until any in-progress dmu buf user evictions complete. */
661 void dmu_buf_user_evict_wait(void);
662 
663 /*
664  * Returns the blkptr associated with this dbuf, or NULL if not set.
665  */
666 struct blkptr *dmu_buf_get_blkptr(dmu_buf_t *db);
667 
668 /*
669  * Indicate that you are going to modify the buffer's data (db_data).
670  *
671  * The transaction (tx) must be assigned to a txg (ie. you've called
672  * dmu_tx_assign()).  The buffer's object must be held in the tx
673  * (ie. you've called dmu_tx_hold_object(tx, db->db_object)).
674  */
675 void dmu_buf_will_dirty(dmu_buf_t *db, dmu_tx_t *tx);
676 
677 /*
678  * You must create a transaction, then hold the objects which you will
679  * (or might) modify as part of this transaction.  Then you must assign
680  * the transaction to a transaction group.  Once the transaction has
681  * been assigned, you can modify buffers which belong to held objects as
682  * part of this transaction.  You can't modify buffers before the
683  * transaction has been assigned; you can't modify buffers which don't
684  * belong to objects which this transaction holds; you can't hold
685  * objects once the transaction has been assigned.  You may hold an
686  * object which you are going to free (with dmu_object_free()), but you
687  * don't have to.
688  *
689  * You can abort the transaction before it has been assigned.
690  *
691  * Note that you may hold buffers (with dmu_buf_hold) at any time,
692  * regardless of transaction state.
693  */
694 
695 #define	DMU_NEW_OBJECT	(-1ULL)
696 #define	DMU_OBJECT_END	(-1ULL)
697 
698 dmu_tx_t *dmu_tx_create(objset_t *os);
699 void dmu_tx_hold_write(dmu_tx_t *tx, uint64_t object, uint64_t off, int len);
700 void dmu_tx_hold_write_by_dnode(dmu_tx_t *tx, dnode_t *dn, uint64_t off,
701     int len);
702 void dmu_tx_hold_free(dmu_tx_t *tx, uint64_t object, uint64_t off,
703     uint64_t len);
704 void dmu_tx_hold_free_by_dnode(dmu_tx_t *tx, dnode_t *dn, uint64_t off,
705     uint64_t len);
706 void dmu_tx_hold_remap_l1indirect(dmu_tx_t *tx, uint64_t object);
707 void dmu_tx_hold_zap(dmu_tx_t *tx, uint64_t object, int add, const char *name);
708 void dmu_tx_hold_zap_by_dnode(dmu_tx_t *tx, dnode_t *dn, int add,
709     const char *name);
710 void dmu_tx_hold_bonus(dmu_tx_t *tx, uint64_t object);
711 void dmu_tx_hold_bonus_by_dnode(dmu_tx_t *tx, dnode_t *dn);
712 void dmu_tx_hold_spill(dmu_tx_t *tx, uint64_t object);
713 void dmu_tx_hold_sa(dmu_tx_t *tx, struct sa_handle *hdl, boolean_t may_grow);
714 void dmu_tx_hold_sa_create(dmu_tx_t *tx, int total_size);
715 void dmu_tx_abort(dmu_tx_t *tx);
716 int dmu_tx_assign(dmu_tx_t *tx, uint64_t txg_how);
717 void dmu_tx_wait(dmu_tx_t *tx);
718 void dmu_tx_commit(dmu_tx_t *tx);
719 void dmu_tx_mark_netfree(dmu_tx_t *tx);
720 
721 /*
722  * To register a commit callback, dmu_tx_callback_register() must be called.
723  *
724  * dcb_data is a pointer to caller private data that is passed on as a
725  * callback parameter. The caller is responsible for properly allocating and
726  * freeing it.
727  *
728  * When registering a callback, the transaction must be already created, but
729  * it cannot be committed or aborted. It can be assigned to a txg or not.
730  *
731  * The callback will be called after the transaction has been safely written
732  * to stable storage and will also be called if the dmu_tx is aborted.
733  * If there is any error which prevents the transaction from being committed to
734  * disk, the callback will be called with a value of error != 0.
735  */
736 typedef void dmu_tx_callback_func_t(void *dcb_data, int error);
737 
738 void dmu_tx_callback_register(dmu_tx_t *tx, dmu_tx_callback_func_t *dcb_func,
739     void *dcb_data);
740 
741 /*
742  * Free up the data blocks for a defined range of a file.  If size is
743  * -1, the range from offset to end-of-file is freed.
744  */
745 int dmu_free_range(objset_t *os, uint64_t object, uint64_t offset,
746 	uint64_t size, dmu_tx_t *tx);
747 int dmu_free_long_range(objset_t *os, uint64_t object, uint64_t offset,
748 	uint64_t size);
749 int dmu_free_long_object(objset_t *os, uint64_t object);
750 
751 /*
752  * Convenience functions.
753  *
754  * Canfail routines will return 0 on success, or an errno if there is a
755  * nonrecoverable I/O error.
756  */
757 #define	DMU_READ_PREFETCH	0 /* prefetch */
758 #define	DMU_READ_NO_PREFETCH	1 /* don't prefetch */
759 int dmu_read(objset_t *os, uint64_t object, uint64_t offset, uint64_t size,
760 	void *buf, uint32_t flags);
761 int dmu_read_by_dnode(dnode_t *dn, uint64_t offset, uint64_t size, void *buf,
762     uint32_t flags);
763 void dmu_write(objset_t *os, uint64_t object, uint64_t offset, uint64_t size,
764 	const void *buf, dmu_tx_t *tx);
765 void dmu_write_by_dnode(dnode_t *dn, uint64_t offset, uint64_t size,
766     const void *buf, dmu_tx_t *tx);
767 void dmu_prealloc(objset_t *os, uint64_t object, uint64_t offset, uint64_t size,
768 	dmu_tx_t *tx);
769 int dmu_read_uio(objset_t *os, uint64_t object, struct uio *uio, uint64_t size);
770 int dmu_read_uio_dbuf(dmu_buf_t *zdb, struct uio *uio, uint64_t size);
771 int dmu_read_uio_dnode(dnode_t *dn, struct uio *uio, uint64_t size);
772 int dmu_write_uio(objset_t *os, uint64_t object, struct uio *uio, uint64_t size,
773     dmu_tx_t *tx);
774 int dmu_write_uio_dbuf(dmu_buf_t *zdb, struct uio *uio, uint64_t size,
775     dmu_tx_t *tx);
776 int dmu_write_uio_dnode(dnode_t *dn, struct uio *uio, uint64_t size,
777     dmu_tx_t *tx);
778 int dmu_write_pages(objset_t *os, uint64_t object, uint64_t offset,
779     uint64_t size, struct page *pp, dmu_tx_t *tx);
780 struct arc_buf *dmu_request_arcbuf(dmu_buf_t *handle, int size);
781 void dmu_return_arcbuf(struct arc_buf *buf);
782 void dmu_assign_arcbuf_dnode(dnode_t *handle, uint64_t offset,
783     struct arc_buf *buf, dmu_tx_t *tx);
784 void dmu_assign_arcbuf(dmu_buf_t *handle, uint64_t offset, struct arc_buf *buf,
785     dmu_tx_t *tx);
786 int dmu_xuio_init(struct xuio *uio, int niov);
787 void dmu_xuio_fini(struct xuio *uio);
788 int dmu_xuio_add(struct xuio *uio, struct arc_buf *abuf, offset_t off,
789     size_t n);
790 int dmu_xuio_cnt(struct xuio *uio);
791 struct arc_buf *dmu_xuio_arcbuf(struct xuio *uio, int i);
792 void dmu_xuio_clear(struct xuio *uio, int i);
793 void xuio_stat_wbuf_copied(void);
794 void xuio_stat_wbuf_nocopy(void);
795 
796 extern boolean_t zfs_prefetch_disable;
797 extern int zfs_max_recordsize;
798 
799 /*
800  * Asynchronously try to read in the data.
801  */
802 void dmu_prefetch(objset_t *os, uint64_t object, int64_t level, uint64_t offset,
803     uint64_t len, enum zio_priority pri);
804 
805 typedef struct dmu_object_info {
806 	/* All sizes are in bytes unless otherwise indicated. */
807 	uint32_t doi_data_block_size;
808 	uint32_t doi_metadata_block_size;
809 	dmu_object_type_t doi_type;
810 	dmu_object_type_t doi_bonus_type;
811 	uint64_t doi_bonus_size;
812 	uint8_t doi_indirection;		/* 2 = dnode->indirect->data */
813 	uint8_t doi_checksum;
814 	uint8_t doi_compress;
815 	uint8_t doi_nblkptr;
816 	int8_t doi_pad[4];
817 	uint64_t doi_dnodesize;
818 	uint64_t doi_physical_blocks_512;	/* data + metadata, 512b blks */
819 	uint64_t doi_max_offset;
820 	uint64_t doi_fill_count;		/* number of non-empty blocks */
821 } dmu_object_info_t;
822 
823 typedef void arc_byteswap_func_t(void *buf, size_t size);
824 
825 typedef struct dmu_object_type_info {
826 	dmu_object_byteswap_t	ot_byteswap;
827 	boolean_t		ot_metadata;
828 	boolean_t		ot_dbuf_metadata_cache;
829 	char			*ot_name;
830 } dmu_object_type_info_t;
831 
832 typedef struct dmu_object_byteswap_info {
833 	arc_byteswap_func_t	*ob_func;
834 	char			*ob_name;
835 } dmu_object_byteswap_info_t;
836 
837 extern const dmu_object_type_info_t dmu_ot[DMU_OT_NUMTYPES];
838 extern const dmu_object_byteswap_info_t dmu_ot_byteswap[DMU_BSWAP_NUMFUNCS];
839 
840 /*
841  * Get information on a DMU object.
842  *
843  * Return 0 on success or ENOENT if object is not allocated.
844  *
845  * If doi is NULL, just indicates whether the object exists.
846  */
847 int dmu_object_info(objset_t *os, uint64_t object, dmu_object_info_t *doi);
848 /* Like dmu_object_info, but faster if you have a held dnode in hand. */
849 void dmu_object_info_from_dnode(dnode_t *dn, dmu_object_info_t *doi);
850 /* Like dmu_object_info, but faster if you have a held dbuf in hand. */
851 void dmu_object_info_from_db(dmu_buf_t *db, dmu_object_info_t *doi);
852 /*
853  * Like dmu_object_info_from_db, but faster still when you only care about
854  * the size.  This is specifically optimized for zfs_getattr().
855  */
856 void dmu_object_size_from_db(dmu_buf_t *db, uint32_t *blksize,
857     u_longlong_t *nblk512);
858 
859 void dmu_object_dnsize_from_db(dmu_buf_t *db, int *dnsize);
860 
861 typedef struct dmu_objset_stats {
862 	uint64_t dds_num_clones; /* number of clones of this */
863 	uint64_t dds_creation_txg;
864 	uint64_t dds_guid;
865 	dmu_objset_type_t dds_type;
866 	uint8_t dds_is_snapshot;
867 	uint8_t dds_inconsistent;
868 	char dds_origin[ZFS_MAX_DATASET_NAME_LEN];
869 } dmu_objset_stats_t;
870 
871 /*
872  * Get stats on a dataset.
873  */
874 void dmu_objset_fast_stat(objset_t *os, dmu_objset_stats_t *stat);
875 
876 /*
877  * Add entries to the nvlist for all the objset's properties.  See
878  * zfs_prop_table[] and zfs(1m) for details on the properties.
879  */
880 void dmu_objset_stats(objset_t *os, struct nvlist *nv);
881 
882 /*
883  * Get the space usage statistics for statvfs().
884  *
885  * refdbytes is the amount of space "referenced" by this objset.
886  * availbytes is the amount of space available to this objset, taking
887  * into account quotas & reservations, assuming that no other objsets
888  * use the space first.  These values correspond to the 'referenced' and
889  * 'available' properties, described in the zfs(1m) manpage.
890  *
891  * usedobjs and availobjs are the number of objects currently allocated,
892  * and available.
893  */
894 void dmu_objset_space(objset_t *os, uint64_t *refdbytesp, uint64_t *availbytesp,
895     uint64_t *usedobjsp, uint64_t *availobjsp);
896 
897 /*
898  * The fsid_guid is a 56-bit ID that can change to avoid collisions.
899  * (Contrast with the ds_guid which is a 64-bit ID that will never
900  * change, so there is a small probability that it will collide.)
901  */
902 uint64_t dmu_objset_fsid_guid(objset_t *os);
903 
904 /*
905  * Get the [cm]time for an objset's snapshot dir
906  */
907 timestruc_t dmu_objset_snap_cmtime(objset_t *os);
908 
909 int dmu_objset_is_snapshot(objset_t *os);
910 
911 extern struct spa *dmu_objset_spa(objset_t *os);
912 extern struct zilog *dmu_objset_zil(objset_t *os);
913 extern struct dsl_pool *dmu_objset_pool(objset_t *os);
914 extern struct dsl_dataset *dmu_objset_ds(objset_t *os);
915 extern void dmu_objset_name(objset_t *os, char *buf);
916 extern dmu_objset_type_t dmu_objset_type(objset_t *os);
917 extern uint64_t dmu_objset_id(objset_t *os);
918 extern uint64_t dmu_objset_dnodesize(objset_t *os);
919 extern zfs_sync_type_t dmu_objset_syncprop(objset_t *os);
920 extern zfs_logbias_op_t dmu_objset_logbias(objset_t *os);
921 extern int dmu_snapshot_list_next(objset_t *os, int namelen, char *name,
922     uint64_t *id, uint64_t *offp, boolean_t *case_conflict);
923 extern int dmu_snapshot_realname(objset_t *os, char *name, char *real,
924     int maxlen, boolean_t *conflict);
925 extern int dmu_dir_list_next(objset_t *os, int namelen, char *name,
926     uint64_t *idp, uint64_t *offp);
927 
928 typedef int objset_used_cb_t(dmu_object_type_t bonustype,
929     void *bonus, uint64_t *userp, uint64_t *groupp);
930 extern void dmu_objset_register_type(dmu_objset_type_t ost,
931     objset_used_cb_t *cb);
932 extern void dmu_objset_set_user(objset_t *os, void *user_ptr);
933 extern void *dmu_objset_get_user(objset_t *os);
934 
935 /*
936  * Return the txg number for the given assigned transaction.
937  */
938 uint64_t dmu_tx_get_txg(dmu_tx_t *tx);
939 
940 /*
941  * Synchronous write.
942  * If a parent zio is provided this function initiates a write on the
943  * provided buffer as a child of the parent zio.
944  * In the absence of a parent zio, the write is completed synchronously.
945  * At write completion, blk is filled with the bp of the written block.
946  * Note that while the data covered by this function will be on stable
947  * storage when the write completes this new data does not become a
948  * permanent part of the file until the associated transaction commits.
949  */
950 
951 /*
952  * {zfs,zvol,ztest}_get_done() args
953  */
954 typedef struct zgd {
955 	struct lwb	*zgd_lwb;
956 	struct blkptr	*zgd_bp;
957 	dmu_buf_t	*zgd_db;
958 	struct locked_range *zgd_lr;
959 	void		*zgd_private;
960 } zgd_t;
961 
962 typedef void dmu_sync_cb_t(zgd_t *arg, int error);
963 int dmu_sync(struct zio *zio, uint64_t txg, dmu_sync_cb_t *done, zgd_t *zgd);
964 
965 /*
966  * Find the next hole or data block in file starting at *off
967  * Return found offset in *off. Return ESRCH for end of file.
968  */
969 int dmu_offset_next(objset_t *os, uint64_t object, boolean_t hole,
970     uint64_t *off);
971 
972 /*
973  * Check if a DMU object has any dirty blocks. If so, sync out
974  * all pending transaction groups. Otherwise, this function
975  * does not alter DMU state. This could be improved to only sync
976  * out the necessary transaction groups for this particular
977  * object.
978  */
979 int dmu_object_wait_synced(objset_t *os, uint64_t object);
980 
981 /*
982  * Initial setup and final teardown.
983  */
984 extern void dmu_init(void);
985 extern void dmu_fini(void);
986 
987 typedef void (*dmu_traverse_cb_t)(objset_t *os, void *arg, struct blkptr *bp,
988     uint64_t object, uint64_t offset, int len);
989 void dmu_traverse_objset(objset_t *os, uint64_t txg_start,
990     dmu_traverse_cb_t cb, void *arg);
991 
992 int dmu_diff(const char *tosnap_name, const char *fromsnap_name,
993     struct vnode *vp, offset_t *offp);
994 
995 /* CRC64 table */
996 #define	ZFS_CRC64_POLY	0xC96C5795D7870F42ULL	/* ECMA-182, reflected form */
997 extern uint64_t zfs_crc64_table[256];
998 
999 extern int zfs_mdcomp_disable;
1000 
1001 #ifdef	__cplusplus
1002 }
1003 #endif
1004 
1005 #endif	/* _SYS_DMU_H */
1006