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) 2013 by Delphix. All rights reserved.
  25  * Copyright 2011 Nexenta Systems, Inc. All rights reserved.
  26  * Copyright (c) 2012, Joyent, Inc. All rights reserved.
  27  */
  28 
  29 /* Portions Copyright 2010 Robert Milkowski */
  30 
  31 #ifndef _SYS_DMU_H
  32 #define _SYS_DMU_H
  33 
  34 /*
  35  * This file describes the interface that the DMU provides for its
  36  * consumers.
  37  *
  38  * The DMU also interacts with the SPA.  That interface is described in
  39  * dmu_spa.h.
  40  */
  41 
  42 #include <sys/inttypes.h>
  43 #include <sys/types.h>
  44 #include <sys/param.h>
  45 #include <sys/cred.h>
  46 #include <sys/time.h>
  47 #include <sys/fs/zfs.h>
  48 
  49 #ifdef  __cplusplus
  50 extern "C" {
  51 #endif
  52 
  53 struct uio;
  54 struct xuio;
  55 struct page;
  56 struct vnode;
  57 struct spa;
  58 struct zilog;
  59 struct zio;
  60 struct blkptr;
  61 struct zap_cursor;
  62 struct dsl_dataset;
  63 struct dsl_pool;
  64 struct dnode;
  65 struct drr_begin;
  66 struct drr_end;
  67 struct zbookmark;
  68 struct spa;
  69 struct nvlist;
  70 struct arc_buf;
  71 struct zio_prop;
  72 struct sa_handle;
  73 
  74 typedef struct objset objset_t;
  75 typedef struct dmu_tx dmu_tx_t;
  76 typedef struct dsl_dir dsl_dir_t;
  77 
  78 typedef enum dmu_object_byteswap {
  79         DMU_BSWAP_UINT8,
  80         DMU_BSWAP_UINT16,
  81         DMU_BSWAP_UINT32,
  82         DMU_BSWAP_UINT64,
  83         DMU_BSWAP_ZAP,
  84         DMU_BSWAP_DNODE,
  85         DMU_BSWAP_OBJSET,
  86         DMU_BSWAP_ZNODE,
  87         DMU_BSWAP_OLDACL,
  88         DMU_BSWAP_ACL,
  89         /*
  90          * Allocating a new byteswap type number makes the on-disk format
  91          * incompatible with any other format that uses the same number.
  92          *
  93          * Data can usually be structured to work with one of the
  94          * DMU_BSWAP_UINT* or DMU_BSWAP_ZAP types.
  95          */
  96         DMU_BSWAP_NUMFUNCS
  97 } dmu_object_byteswap_t;
  98 
  99 #define DMU_OT_NEWTYPE 0x80
 100 #define DMU_OT_METADATA 0x40
 101 #define DMU_OT_BYTESWAP_MASK 0x3f
 102 
 103 /*
 104  * Defines a uint8_t object type. Object types specify if the data
 105  * in the object is metadata (boolean) and how to byteswap the data
 106  * (dmu_object_byteswap_t).
 107  */
 108 #define DMU_OT(byteswap, metadata) \
 109         (DMU_OT_NEWTYPE | \
 110         ((metadata) ? DMU_OT_METADATA : 0) | \
 111         ((byteswap) & DMU_OT_BYTESWAP_MASK))
 112 
 113 #define DMU_OT_IS_VALID(ot) (((ot) & DMU_OT_NEWTYPE) ? \
 114         ((ot) & DMU_OT_BYTESWAP_MASK) < DMU_BSWAP_NUMFUNCS : \
 115         (ot) < DMU_OT_NUMTYPES)
 116 
 117 #define DMU_OT_IS_METADATA(ot) (((ot) & DMU_OT_NEWTYPE) ? \
 118         ((ot) & DMU_OT_METADATA) : \
 119         dmu_ot[(ot)].ot_metadata)
 120 
 121 #define DMU_OT_BYTESWAP(ot) (((ot) & DMU_OT_NEWTYPE) ? \
 122         ((ot) & DMU_OT_BYTESWAP_MASK) : \
 123         dmu_ot[(ot)].ot_byteswap)
 124 
 125 typedef enum dmu_object_type {
 126         DMU_OT_NONE,
 127         /* general: */
 128         DMU_OT_OBJECT_DIRECTORY,        /* ZAP */
 129         DMU_OT_OBJECT_ARRAY,            /* UINT64 */
 130         DMU_OT_PACKED_NVLIST,           /* UINT8 (XDR by nvlist_pack/unpack) */
 131         DMU_OT_PACKED_NVLIST_SIZE,      /* UINT64 */
 132         DMU_OT_BPOBJ,                   /* UINT64 */
 133         DMU_OT_BPOBJ_HDR,               /* UINT64 */
 134         /* spa: */
 135         DMU_OT_SPACE_MAP_HEADER,        /* UINT64 */
 136         DMU_OT_SPACE_MAP,               /* UINT64 */
 137         /* zil: */
 138         DMU_OT_INTENT_LOG,              /* UINT64 */
 139         /* dmu: */
 140         DMU_OT_DNODE,                   /* DNODE */
 141         DMU_OT_OBJSET,                  /* OBJSET */
 142         /* dsl: */
 143         DMU_OT_DSL_DIR,                 /* UINT64 */
 144         DMU_OT_DSL_DIR_CHILD_MAP,       /* ZAP */
 145         DMU_OT_DSL_DS_SNAP_MAP,         /* ZAP */
 146         DMU_OT_DSL_PROPS,               /* ZAP */
 147         DMU_OT_DSL_DATASET,             /* UINT64 */
 148         /* zpl: */
 149         DMU_OT_ZNODE,                   /* ZNODE */
 150         DMU_OT_OLDACL,                  /* Old ACL */
 151         DMU_OT_PLAIN_FILE_CONTENTS,     /* UINT8 */
 152         DMU_OT_DIRECTORY_CONTENTS,      /* ZAP */
 153         DMU_OT_MASTER_NODE,             /* ZAP */
 154         DMU_OT_UNLINKED_SET,            /* ZAP */
 155         /* zvol: */
 156         DMU_OT_ZVOL,                    /* UINT8 */
 157         DMU_OT_ZVOL_PROP,               /* ZAP */
 158         /* other; for testing only! */
 159         DMU_OT_PLAIN_OTHER,             /* UINT8 */
 160         DMU_OT_UINT64_OTHER,            /* UINT64 */
 161         DMU_OT_ZAP_OTHER,               /* ZAP */
 162         /* new object types: */
 163         DMU_OT_ERROR_LOG,               /* ZAP */
 164         DMU_OT_SPA_HISTORY,             /* UINT8 */
 165         DMU_OT_SPA_HISTORY_OFFSETS,     /* spa_his_phys_t */
 166         DMU_OT_POOL_PROPS,              /* ZAP */
 167         DMU_OT_DSL_PERMS,               /* ZAP */
 168         DMU_OT_ACL,                     /* ACL */
 169         DMU_OT_SYSACL,                  /* SYSACL */
 170         DMU_OT_FUID,                    /* FUID table (Packed NVLIST UINT8) */
 171         DMU_OT_FUID_SIZE,               /* FUID table size UINT64 */
 172         DMU_OT_NEXT_CLONES,             /* ZAP */
 173         DMU_OT_SCAN_QUEUE,              /* ZAP */
 174         DMU_OT_USERGROUP_USED,          /* ZAP */
 175         DMU_OT_USERGROUP_QUOTA,         /* ZAP */
 176         DMU_OT_USERREFS,                /* ZAP */
 177         DMU_OT_DDT_ZAP,                 /* ZAP */
 178         DMU_OT_DDT_STATS,               /* ZAP */
 179         DMU_OT_SA,                      /* System attr */
 180         DMU_OT_SA_MASTER_NODE,          /* ZAP */
 181         DMU_OT_SA_ATTR_REGISTRATION,    /* ZAP */
 182         DMU_OT_SA_ATTR_LAYOUTS,         /* ZAP */
 183         DMU_OT_SCAN_XLATE,              /* ZAP */
 184         DMU_OT_DEDUP,                   /* fake dedup BP from ddt_bp_create() */
 185         DMU_OT_DEADLIST,                /* ZAP */
 186         DMU_OT_DEADLIST_HDR,            /* UINT64 */
 187         DMU_OT_DSL_CLONES,              /* ZAP */
 188         DMU_OT_BPOBJ_SUBOBJ,            /* UINT64 */
 189         /*
 190          * Do not allocate new object types here. Doing so makes the on-disk
 191          * format incompatible with any other format that uses the same object
 192          * type number.
 193          *
 194          * When creating an object which does not have one of the above types
 195          * use the DMU_OTN_* type with the correct byteswap and metadata
 196          * values.
 197          *
 198          * The DMU_OTN_* types do not have entries in the dmu_ot table,
 199          * use the DMU_OT_IS_METDATA() and DMU_OT_BYTESWAP() macros instead
 200          * of indexing into dmu_ot directly (this works for both DMU_OT_* types
 201          * and DMU_OTN_* types).
 202          */
 203         DMU_OT_NUMTYPES,
 204 
 205         /*
 206          * Names for valid types declared with DMU_OT().
 207          */
 208         DMU_OTN_UINT8_DATA = DMU_OT(DMU_BSWAP_UINT8, B_FALSE),
 209         DMU_OTN_UINT8_METADATA = DMU_OT(DMU_BSWAP_UINT8, B_TRUE),
 210         DMU_OTN_UINT16_DATA = DMU_OT(DMU_BSWAP_UINT16, B_FALSE),
 211         DMU_OTN_UINT16_METADATA = DMU_OT(DMU_BSWAP_UINT16, B_TRUE),
 212         DMU_OTN_UINT32_DATA = DMU_OT(DMU_BSWAP_UINT32, B_FALSE),
 213         DMU_OTN_UINT32_METADATA = DMU_OT(DMU_BSWAP_UINT32, B_TRUE),
 214         DMU_OTN_UINT64_DATA = DMU_OT(DMU_BSWAP_UINT64, B_FALSE),
 215         DMU_OTN_UINT64_METADATA = DMU_OT(DMU_BSWAP_UINT64, B_TRUE),
 216         DMU_OTN_ZAP_DATA = DMU_OT(DMU_BSWAP_ZAP, B_FALSE),
 217         DMU_OTN_ZAP_METADATA = DMU_OT(DMU_BSWAP_ZAP, B_TRUE),
 218 } dmu_object_type_t;
 219 
 220 typedef enum txg_how {
 221         TXG_WAIT = 1,
 222         TXG_NOWAIT,
 223 } txg_how_t;
 224 
 225 void byteswap_uint64_array(void *buf, size_t size);
 226 void byteswap_uint32_array(void *buf, size_t size);
 227 void byteswap_uint16_array(void *buf, size_t size);
 228 void byteswap_uint8_array(void *buf, size_t size);
 229 void zap_byteswap(void *buf, size_t size);
 230 void zfs_oldacl_byteswap(void *buf, size_t size);
 231 void zfs_acl_byteswap(void *buf, size_t size);
 232 void zfs_znode_byteswap(void *buf, size_t size);
 233 
 234 #define DS_FIND_SNAPSHOTS       (1<<0)
 235 #define DS_FIND_CHILDREN        (1<<1)
 236 
 237 /*
 238  * The maximum number of bytes that can be accessed as part of one
 239  * operation, including metadata.
 240  */
 241 #define DMU_MAX_ACCESS (10<<20) /* 10MB */
 242 #define DMU_MAX_DELETEBLKCNT (20480) /* ~5MB of indirect blocks */
 243 
 244 #define DMU_USERUSED_OBJECT     (-1ULL)
 245 #define DMU_GROUPUSED_OBJECT    (-2ULL)
 246 #define DMU_DEADLIST_OBJECT     (-3ULL)
 247 
 248 /*
 249  * artificial blkids for bonus buffer and spill blocks
 250  */
 251 #define DMU_BONUS_BLKID         (-1ULL)
 252 #define DMU_SPILL_BLKID         (-2ULL)
 253 /*
 254  * Public routines to create, destroy, open, and close objsets.
 255  */
 256 int dmu_objset_hold(const char *name, void *tag, objset_t **osp);
 257 int dmu_objset_own(const char *name, dmu_objset_type_t type,
 258     boolean_t readonly, void *tag, objset_t **osp);
 259 void dmu_objset_rele(objset_t *os, void *tag);
 260 void dmu_objset_disown(objset_t *os, void *tag);
 261 int dmu_objset_open_ds(struct dsl_dataset *ds, objset_t **osp);
 262 
 263 void dmu_objset_evict_dbufs(objset_t *os);
 264 int dmu_objset_create(const char *name, dmu_objset_type_t type, uint64_t flags,
 265     void (*func)(objset_t *os, void *arg, cred_t *cr, dmu_tx_t *tx), void *arg);
 266 int dmu_objset_clone(const char *name, const char *origin);
 267 int dsl_destroy_snapshots_nvl(struct nvlist *snaps, boolean_t defer,
 268     struct nvlist *errlist);
 269 int dmu_objset_snapshot_one(const char *fsname, const char *snapname);
 270 int dmu_objset_snapshot_tmp(const char *, const char *, int);
 271 int dmu_objset_find(char *name, int func(const char *, void *), void *arg,
 272     int flags);
 273 void dmu_objset_byteswap(void *buf, size_t size);
 274 int dsl_dataset_rename_snapshot(const char *fsname,
 275     const char *oldsnapname, const char *newsnapname, boolean_t recursive);
 276 
 277 typedef struct dmu_buf {
 278         uint64_t db_object;             /* object that this buffer is part of */
 279         uint64_t db_offset;             /* byte offset in this object */
 280         uint64_t db_size;               /* size of buffer in bytes */
 281         void *db_data;                  /* data in buffer */
 282 } dmu_buf_t;
 283 
 284 typedef void dmu_buf_evict_func_t(struct dmu_buf *db, void *user_ptr);
 285 
 286 /*
 287  * The names of zap entries in the DIRECTORY_OBJECT of the MOS.
 288  */
 289 #define DMU_POOL_DIRECTORY_OBJECT       1
 290 #define DMU_POOL_CONFIG                 "config"
 291 #define DMU_POOL_FEATURES_FOR_WRITE     "features_for_write"
 292 #define DMU_POOL_FEATURES_FOR_READ      "features_for_read"
 293 #define DMU_POOL_FEATURE_DESCRIPTIONS   "feature_descriptions"
 294 #define DMU_POOL_ROOT_DATASET           "root_dataset"
 295 #define DMU_POOL_SYNC_BPOBJ             "sync_bplist"
 296 #define DMU_POOL_ERRLOG_SCRUB           "errlog_scrub"
 297 #define DMU_POOL_ERRLOG_LAST            "errlog_last"
 298 #define DMU_POOL_SPARES                 "spares"
 299 #define DMU_POOL_DEFLATE                "deflate"
 300 #define DMU_POOL_HISTORY                "history"
 301 #define DMU_POOL_PROPS                  "pool_props"
 302 #define DMU_POOL_L2CACHE                "l2cache"
 303 #define DMU_POOL_TMP_USERREFS           "tmp_userrefs"
 304 #define DMU_POOL_DDT                    "DDT-%s-%s-%s"
 305 #define DMU_POOL_DDT_STATS              "DDT-statistics"
 306 #define DMU_POOL_CREATION_VERSION       "creation_version"
 307 #define DMU_POOL_SCAN                   "scan"
 308 #define DMU_POOL_FREE_BPOBJ             "free_bpobj"
 309 #define DMU_POOL_BPTREE_OBJ             "bptree_obj"
 310 #define DMU_POOL_EMPTY_BPOBJ            "empty_bpobj"
 311 
 312 /*
 313  * Allocate an object from this objset.  The range of object numbers
 314  * available is (0, DN_MAX_OBJECT).  Object 0 is the meta-dnode.
 315  *
 316  * The transaction must be assigned to a txg.  The newly allocated
 317  * object will be "held" in the transaction (ie. you can modify the
 318  * newly allocated object in this transaction).
 319  *
 320  * dmu_object_alloc() chooses an object and returns it in *objectp.
 321  *
 322  * dmu_object_claim() allocates a specific object number.  If that
 323  * number is already allocated, it fails and returns EEXIST.
 324  *
 325  * Return 0 on success, or ENOSPC or EEXIST as specified above.
 326  */
 327 uint64_t dmu_object_alloc(objset_t *os, dmu_object_type_t ot,
 328     int blocksize, dmu_object_type_t bonus_type, int bonus_len, dmu_tx_t *tx);
 329 int dmu_object_claim(objset_t *os, uint64_t object, dmu_object_type_t ot,
 330     int blocksize, dmu_object_type_t bonus_type, int bonus_len, dmu_tx_t *tx);
 331 int dmu_object_reclaim(objset_t *os, uint64_t object, dmu_object_type_t ot,
 332     int blocksize, dmu_object_type_t bonustype, int bonuslen);
 333 
 334 /*
 335  * Free an object from this objset.
 336  *
 337  * The object's data will be freed as well (ie. you don't need to call
 338  * dmu_free(object, 0, -1, tx)).
 339  *
 340  * The object need not be held in the transaction.
 341  *
 342  * If there are any holds on this object's buffers (via dmu_buf_hold()),
 343  * or tx holds on the object (via dmu_tx_hold_object()), you can not
 344  * free it; it fails and returns EBUSY.
 345  *
 346  * If the object is not allocated, it fails and returns ENOENT.
 347  *
 348  * Return 0 on success, or EBUSY or ENOENT as specified above.
 349  */
 350 int dmu_object_free(objset_t *os, uint64_t object, dmu_tx_t *tx);
 351 
 352 /*
 353  * Find the next allocated or free object.
 354  *
 355  * The objectp parameter is in-out.  It will be updated to be the next
 356  * object which is allocated.  Ignore objects which have not been
 357  * modified since txg.
 358  *
 359  * XXX Can only be called on a objset with no dirty data.
 360  *
 361  * Returns 0 on success, or ENOENT if there are no more objects.
 362  */
 363 int dmu_object_next(objset_t *os, uint64_t *objectp,
 364     boolean_t hole, uint64_t txg);
 365 
 366 /*
 367  * Set the data blocksize for an object.
 368  *
 369  * The object cannot have any blocks allcated beyond the first.  If
 370  * the first block is allocated already, the new size must be greater
 371  * than the current block size.  If these conditions are not met,
 372  * ENOTSUP will be returned.
 373  *
 374  * Returns 0 on success, or EBUSY if there are any holds on the object
 375  * contents, or ENOTSUP as described above.
 376  */
 377 int dmu_object_set_blocksize(objset_t *os, uint64_t object, uint64_t size,
 378     int ibs, dmu_tx_t *tx);
 379 
 380 /*
 381  * Set the checksum property on a dnode.  The new checksum algorithm will
 382  * apply to all newly written blocks; existing blocks will not be affected.
 383  */
 384 void dmu_object_set_checksum(objset_t *os, uint64_t object, uint8_t checksum,
 385     dmu_tx_t *tx);
 386 
 387 /*
 388  * Set the compress property on a dnode.  The new compression algorithm will
 389  * apply to all newly written blocks; existing blocks will not be affected.
 390  */
 391 void dmu_object_set_compress(objset_t *os, uint64_t object, uint8_t compress,
 392     dmu_tx_t *tx);
 393 
 394 /*
 395  * Decide how to write a block: checksum, compression, number of copies, etc.
 396  */
 397 #define WP_NOFILL       0x1
 398 #define WP_DMU_SYNC     0x2
 399 #define WP_SPILL        0x4
 400 
 401 void dmu_write_policy(objset_t *os, struct dnode *dn, int level, int wp,
 402     struct zio_prop *zp);
 403 /*
 404  * The bonus data is accessed more or less like a regular buffer.
 405  * You must dmu_bonus_hold() to get the buffer, which will give you a
 406  * dmu_buf_t with db_offset==-1ULL, and db_size = the size of the bonus
 407  * data.  As with any normal buffer, you must call dmu_buf_read() to
 408  * read db_data, dmu_buf_will_dirty() before modifying it, and the
 409  * object must be held in an assigned transaction before calling
 410  * dmu_buf_will_dirty.  You may use dmu_buf_set_user() on the bonus
 411  * buffer as well.  You must release your hold with dmu_buf_rele().
 412  *
 413  * Returns ENOENT, EIO, or 0.
 414  */
 415 int dmu_bonus_hold(objset_t *os, uint64_t object, void *tag, dmu_buf_t **);
 416 int dmu_bonus_max(void);
 417 int dmu_set_bonus(dmu_buf_t *, int, dmu_tx_t *);
 418 int dmu_set_bonustype(dmu_buf_t *, dmu_object_type_t, dmu_tx_t *);
 419 dmu_object_type_t dmu_get_bonustype(dmu_buf_t *);
 420 int dmu_rm_spill(objset_t *, uint64_t, dmu_tx_t *);
 421 
 422 /*
 423  * Special spill buffer support used by "SA" framework
 424  */
 425 
 426 int dmu_spill_hold_by_bonus(dmu_buf_t *bonus, void *tag, dmu_buf_t **dbp);
 427 int dmu_spill_hold_by_dnode(struct dnode *dn, uint32_t flags,
 428     void *tag, dmu_buf_t **dbp);
 429 int dmu_spill_hold_existing(dmu_buf_t *bonus, void *tag, dmu_buf_t **dbp);
 430 
 431 /*
 432  * Obtain the DMU buffer from the specified object which contains the
 433  * specified offset.  dmu_buf_hold() puts a "hold" on the buffer, so
 434  * that it will remain in memory.  You must release the hold with
 435  * dmu_buf_rele().  You musn't access the dmu_buf_t after releasing your
 436  * hold.  You must have a hold on any dmu_buf_t* you pass to the DMU.
 437  *
 438  * You must call dmu_buf_read, dmu_buf_will_dirty, or dmu_buf_will_fill
 439  * on the returned buffer before reading or writing the buffer's
 440  * db_data.  The comments for those routines describe what particular
 441  * operations are valid after calling them.
 442  *
 443  * The object number must be a valid, allocated object number.
 444  */
 445 int dmu_buf_hold(objset_t *os, uint64_t object, uint64_t offset,
 446     void *tag, dmu_buf_t **, int flags);
 447 void dmu_buf_add_ref(dmu_buf_t *db, void* tag);
 448 void dmu_buf_rele(dmu_buf_t *db, void *tag);
 449 uint64_t dmu_buf_refcount(dmu_buf_t *db);
 450 
 451 /*
 452  * dmu_buf_hold_array holds the DMU buffers which contain all bytes in a
 453  * range of an object.  A pointer to an array of dmu_buf_t*'s is
 454  * returned (in *dbpp).
 455  *
 456  * dmu_buf_rele_array releases the hold on an array of dmu_buf_t*'s, and
 457  * frees the array.  The hold on the array of buffers MUST be released
 458  * with dmu_buf_rele_array.  You can NOT release the hold on each buffer
 459  * individually with dmu_buf_rele.
 460  */
 461 int dmu_buf_hold_array_by_bonus(dmu_buf_t *db, uint64_t offset,
 462     uint64_t length, int read, void *tag, int *numbufsp, dmu_buf_t ***dbpp);
 463 void dmu_buf_rele_array(dmu_buf_t **, int numbufs, void *tag);
 464 
 465 /*
 466  * Returns NULL on success, or the existing user ptr if it's already
 467  * been set.
 468  *
 469  * user_ptr is for use by the user and can be obtained via dmu_buf_get_user().
 470  *
 471  * user_data_ptr_ptr should be NULL, or a pointer to a pointer which
 472  * will be set to db->db_data when you are allowed to access it.  Note
 473  * that db->db_data (the pointer) can change when you do dmu_buf_read(),
 474  * dmu_buf_tryupgrade(), dmu_buf_will_dirty(), or dmu_buf_will_fill().
 475  * *user_data_ptr_ptr will be set to the new value when it changes.
 476  *
 477  * If non-NULL, pageout func will be called when this buffer is being
 478  * excised from the cache, so that you can clean up the data structure
 479  * pointed to by user_ptr.
 480  *
 481  * dmu_evict_user() will call the pageout func for all buffers in a
 482  * objset with a given pageout func.
 483  */
 484 void *dmu_buf_set_user(dmu_buf_t *db, void *user_ptr, void *user_data_ptr_ptr,
 485     dmu_buf_evict_func_t *pageout_func);
 486 /*
 487  * set_user_ie is the same as set_user, but request immediate eviction
 488  * when hold count goes to zero.
 489  */
 490 void *dmu_buf_set_user_ie(dmu_buf_t *db, void *user_ptr,
 491     void *user_data_ptr_ptr, dmu_buf_evict_func_t *pageout_func);
 492 void *dmu_buf_update_user(dmu_buf_t *db_fake, void *old_user_ptr,
 493     void *user_ptr, void *user_data_ptr_ptr,
 494     dmu_buf_evict_func_t *pageout_func);
 495 void dmu_evict_user(objset_t *os, dmu_buf_evict_func_t *func);
 496 
 497 /*
 498  * Returns the user_ptr set with dmu_buf_set_user(), or NULL if not set.
 499  */
 500 void *dmu_buf_get_user(dmu_buf_t *db);
 501 
 502 /*
 503  * Returns the blkptr associated with this dbuf, or NULL if not set.
 504  */
 505 struct blkptr *dmu_buf_get_blkptr(dmu_buf_t *db);
 506 
 507 /*
 508  * Indicate that you are going to modify the buffer's data (db_data).
 509  *
 510  * The transaction (tx) must be assigned to a txg (ie. you've called
 511  * dmu_tx_assign()).  The buffer's object must be held in the tx
 512  * (ie. you've called dmu_tx_hold_object(tx, db->db_object)).
 513  */
 514 void dmu_buf_will_dirty(dmu_buf_t *db, dmu_tx_t *tx);
 515 
 516 /*
 517  * Tells if the given dbuf is freeable.
 518  */
 519 boolean_t dmu_buf_freeable(dmu_buf_t *);
 520 
 521 /*
 522  * You must create a transaction, then hold the objects which you will
 523  * (or might) modify as part of this transaction.  Then you must assign
 524  * the transaction to a transaction group.  Once the transaction has
 525  * been assigned, you can modify buffers which belong to held objects as
 526  * part of this transaction.  You can't modify buffers before the
 527  * transaction has been assigned; you can't modify buffers which don't
 528  * belong to objects which this transaction holds; you can't hold
 529  * objects once the transaction has been assigned.  You may hold an
 530  * object which you are going to free (with dmu_object_free()), but you
 531  * don't have to.
 532  *
 533  * You can abort the transaction before it has been assigned.
 534  *
 535  * Note that you may hold buffers (with dmu_buf_hold) at any time,
 536  * regardless of transaction state.
 537  */
 538 
 539 #define DMU_NEW_OBJECT  (-1ULL)
 540 #define DMU_OBJECT_END  (-1ULL)
 541 
 542 dmu_tx_t *dmu_tx_create(objset_t *os);
 543 void dmu_tx_hold_write(dmu_tx_t *tx, uint64_t object, uint64_t off, int len);
 544 void dmu_tx_hold_free(dmu_tx_t *tx, uint64_t object, uint64_t off,
 545     uint64_t len);
 546 void dmu_tx_hold_zap(dmu_tx_t *tx, uint64_t object, int add, const char *name);
 547 void dmu_tx_hold_bonus(dmu_tx_t *tx, uint64_t object);
 548 void dmu_tx_hold_spill(dmu_tx_t *tx, uint64_t object);
 549 void dmu_tx_hold_sa(dmu_tx_t *tx, struct sa_handle *hdl, boolean_t may_grow);
 550 void dmu_tx_hold_sa_create(dmu_tx_t *tx, int total_size);
 551 void dmu_tx_abort(dmu_tx_t *tx);
 552 int dmu_tx_assign(dmu_tx_t *tx, enum txg_how txg_how);
 553 void dmu_tx_wait(dmu_tx_t *tx);
 554 void dmu_tx_commit(dmu_tx_t *tx);
 555 
 556 /*
 557  * To register a commit callback, dmu_tx_callback_register() must be called.
 558  *
 559  * dcb_data is a pointer to caller private data that is passed on as a
 560  * callback parameter. The caller is responsible for properly allocating and
 561  * freeing it.
 562  *
 563  * When registering a callback, the transaction must be already created, but
 564  * it cannot be committed or aborted. It can be assigned to a txg or not.
 565  *
 566  * The callback will be called after the transaction has been safely written
 567  * to stable storage and will also be called if the dmu_tx is aborted.
 568  * If there is any error which prevents the transaction from being committed to
 569  * disk, the callback will be called with a value of error != 0.
 570  */
 571 typedef void dmu_tx_callback_func_t(void *dcb_data, int error);
 572 
 573 void dmu_tx_callback_register(dmu_tx_t *tx, dmu_tx_callback_func_t *dcb_func,
 574     void *dcb_data);
 575 
 576 /*
 577  * Free up the data blocks for a defined range of a file.  If size is
 578  * -1, the range from offset to end-of-file is freed.
 579  */
 580 int dmu_free_range(objset_t *os, uint64_t object, uint64_t offset,
 581         uint64_t size, dmu_tx_t *tx);
 582 int dmu_free_long_range(objset_t *os, uint64_t object, uint64_t offset,
 583         uint64_t size);
 584 int dmu_free_long_object(objset_t *os, uint64_t object);
 585 
 586 /*
 587  * Convenience functions.
 588  *
 589  * Canfail routines will return 0 on success, or an errno if there is a
 590  * nonrecoverable I/O error.
 591  */
 592 #define DMU_READ_PREFETCH       0 /* prefetch */
 593 #define DMU_READ_NO_PREFETCH    1 /* don't prefetch */
 594 int dmu_read(objset_t *os, uint64_t object, uint64_t offset, uint64_t size,
 595         void *buf, uint32_t flags);
 596 void dmu_write(objset_t *os, uint64_t object, uint64_t offset, uint64_t size,
 597         const void *buf, dmu_tx_t *tx);
 598 void dmu_prealloc(objset_t *os, uint64_t object, uint64_t offset, uint64_t size,
 599         dmu_tx_t *tx);
 600 int dmu_read_uio(objset_t *os, uint64_t object, struct uio *uio, uint64_t size);
 601 int dmu_write_uio(objset_t *os, uint64_t object, struct uio *uio, uint64_t size,
 602     dmu_tx_t *tx);
 603 int dmu_write_uio_dbuf(dmu_buf_t *zdb, struct uio *uio, uint64_t size,
 604     dmu_tx_t *tx);
 605 int dmu_write_pages(objset_t *os, uint64_t object, uint64_t offset,
 606     uint64_t size, struct page *pp, dmu_tx_t *tx);
 607 struct arc_buf *dmu_request_arcbuf(dmu_buf_t *handle, int size);
 608 void dmu_return_arcbuf(struct arc_buf *buf);
 609 void dmu_assign_arcbuf(dmu_buf_t *handle, uint64_t offset, struct arc_buf *buf,
 610     dmu_tx_t *tx);
 611 int dmu_xuio_init(struct xuio *uio, int niov);
 612 void dmu_xuio_fini(struct xuio *uio);
 613 int dmu_xuio_add(struct xuio *uio, struct arc_buf *abuf, offset_t off,
 614     size_t n);
 615 int dmu_xuio_cnt(struct xuio *uio);
 616 struct arc_buf *dmu_xuio_arcbuf(struct xuio *uio, int i);
 617 void dmu_xuio_clear(struct xuio *uio, int i);
 618 void xuio_stat_wbuf_copied();
 619 void xuio_stat_wbuf_nocopy();
 620 
 621 extern int zfs_prefetch_disable;
 622 
 623 /*
 624  * Asynchronously try to read in the data.
 625  */
 626 void dmu_prefetch(objset_t *os, uint64_t object, uint64_t offset,
 627     uint64_t len);
 628 
 629 typedef struct dmu_object_info {
 630         /* All sizes are in bytes unless otherwise indicated. */
 631         uint32_t doi_data_block_size;
 632         uint32_t doi_metadata_block_size;
 633         dmu_object_type_t doi_type;
 634         dmu_object_type_t doi_bonus_type;
 635         uint64_t doi_bonus_size;
 636         uint8_t doi_indirection;                /* 2 = dnode->indirect->data */
 637         uint8_t doi_checksum;
 638         uint8_t doi_compress;
 639         uint8_t doi_pad[5];
 640         uint64_t doi_physical_blocks_512;       /* data + metadata, 512b blks */
 641         uint64_t doi_max_offset;
 642         uint64_t doi_fill_count;                /* number of non-empty blocks */
 643 } dmu_object_info_t;
 644 
 645 typedef void arc_byteswap_func_t(void *buf, size_t size);
 646 
 647 typedef struct dmu_object_type_info {
 648         dmu_object_byteswap_t   ot_byteswap;
 649         boolean_t               ot_metadata;
 650         char                    *ot_name;
 651 } dmu_object_type_info_t;
 652 
 653 typedef struct dmu_object_byteswap_info {
 654         arc_byteswap_func_t     *ob_func;
 655         char                    *ob_name;
 656 } dmu_object_byteswap_info_t;
 657 
 658 extern const dmu_object_type_info_t dmu_ot[DMU_OT_NUMTYPES];
 659 extern const dmu_object_byteswap_info_t dmu_ot_byteswap[DMU_BSWAP_NUMFUNCS];
 660 
 661 /*
 662  * Get information on a DMU object.
 663  *
 664  * Return 0 on success or ENOENT if object is not allocated.
 665  *
 666  * If doi is NULL, just indicates whether the object exists.
 667  */
 668 int dmu_object_info(objset_t *os, uint64_t object, dmu_object_info_t *doi);
 669 /* Like dmu_object_info, but faster if you have a held dnode in hand. */
 670 void dmu_object_info_from_dnode(struct dnode *dn, dmu_object_info_t *doi);
 671 /* Like dmu_object_info, but faster if you have a held dbuf in hand. */
 672 void dmu_object_info_from_db(dmu_buf_t *db, dmu_object_info_t *doi);
 673 /*
 674  * Like dmu_object_info_from_db, but faster still when you only care about
 675  * the size.  This is specifically optimized for zfs_getattr().
 676  */
 677 void dmu_object_size_from_db(dmu_buf_t *db, uint32_t *blksize,
 678     u_longlong_t *nblk512);
 679 
 680 typedef struct dmu_objset_stats {
 681         uint64_t dds_num_clones; /* number of clones of this */
 682         uint64_t dds_creation_txg;
 683         uint64_t dds_guid;
 684         dmu_objset_type_t dds_type;
 685         uint8_t dds_is_snapshot;
 686         uint8_t dds_inconsistent;
 687         char dds_origin[MAXNAMELEN];
 688 } dmu_objset_stats_t;
 689 
 690 /*
 691  * Get stats on a dataset.
 692  */
 693 void dmu_objset_fast_stat(objset_t *os, dmu_objset_stats_t *stat);
 694 
 695 /*
 696  * Add entries to the nvlist for all the objset's properties.  See
 697  * zfs_prop_table[] and zfs(1m) for details on the properties.
 698  */
 699 void dmu_objset_stats(objset_t *os, struct nvlist *nv);
 700 
 701 /*
 702  * Get the space usage statistics for statvfs().
 703  *
 704  * refdbytes is the amount of space "referenced" by this objset.
 705  * availbytes is the amount of space available to this objset, taking
 706  * into account quotas & reservations, assuming that no other objsets
 707  * use the space first.  These values correspond to the 'referenced' and
 708  * 'available' properties, described in the zfs(1m) manpage.
 709  *
 710  * usedobjs and availobjs are the number of objects currently allocated,
 711  * and available.
 712  */
 713 void dmu_objset_space(objset_t *os, uint64_t *refdbytesp, uint64_t *availbytesp,
 714     uint64_t *usedobjsp, uint64_t *availobjsp);
 715 
 716 /*
 717  * The fsid_guid is a 56-bit ID that can change to avoid collisions.
 718  * (Contrast with the ds_guid which is a 64-bit ID that will never
 719  * change, so there is a small probability that it will collide.)
 720  */
 721 uint64_t dmu_objset_fsid_guid(objset_t *os);
 722 
 723 /*
 724  * Get the [cm]time for an objset's snapshot dir
 725  */
 726 timestruc_t dmu_objset_snap_cmtime(objset_t *os);
 727 
 728 int dmu_objset_is_snapshot(objset_t *os);
 729 
 730 extern struct spa *dmu_objset_spa(objset_t *os);
 731 extern struct zilog *dmu_objset_zil(objset_t *os);
 732 extern struct dsl_pool *dmu_objset_pool(objset_t *os);
 733 extern struct dsl_dataset *dmu_objset_ds(objset_t *os);
 734 extern void dmu_objset_name(objset_t *os, char *buf);
 735 extern dmu_objset_type_t dmu_objset_type(objset_t *os);
 736 extern uint64_t dmu_objset_id(objset_t *os);
 737 extern uint64_t dmu_objset_syncprop(objset_t *os);
 738 extern uint64_t dmu_objset_logbias(objset_t *os);
 739 extern int dmu_snapshot_list_next(objset_t *os, int namelen, char *name,
 740     uint64_t *id, uint64_t *offp, boolean_t *case_conflict);
 741 extern int dmu_snapshot_realname(objset_t *os, char *name, char *real,
 742     int maxlen, boolean_t *conflict);
 743 extern int dmu_dir_list_next(objset_t *os, int namelen, char *name,
 744     uint64_t *idp, uint64_t *offp);
 745 
 746 typedef int objset_used_cb_t(dmu_object_type_t bonustype,
 747     void *bonus, uint64_t *userp, uint64_t *groupp);
 748 extern void dmu_objset_register_type(dmu_objset_type_t ost,
 749     objset_used_cb_t *cb);
 750 extern void dmu_objset_set_user(objset_t *os, void *user_ptr);
 751 extern void *dmu_objset_get_user(objset_t *os);
 752 
 753 /*
 754  * Return the txg number for the given assigned transaction.
 755  */
 756 uint64_t dmu_tx_get_txg(dmu_tx_t *tx);
 757 
 758 /*
 759  * Synchronous write.
 760  * If a parent zio is provided this function initiates a write on the
 761  * provided buffer as a child of the parent zio.
 762  * In the absence of a parent zio, the write is completed synchronously.
 763  * At write completion, blk is filled with the bp of the written block.
 764  * Note that while the data covered by this function will be on stable
 765  * storage when the write completes this new data does not become a
 766  * permanent part of the file until the associated transaction commits.
 767  */
 768 
 769 /*
 770  * {zfs,zvol,ztest}_get_done() args
 771  */
 772 typedef struct zgd {
 773         struct zilog    *zgd_zilog;
 774         struct blkptr   *zgd_bp;
 775         dmu_buf_t       *zgd_db;
 776         struct rl       *zgd_rl;
 777         void            *zgd_private;
 778 } zgd_t;
 779 
 780 typedef void dmu_sync_cb_t(zgd_t *arg, int error);
 781 int dmu_sync(struct zio *zio, uint64_t txg, dmu_sync_cb_t *done, zgd_t *zgd);
 782 
 783 /*
 784  * Find the next hole or data block in file starting at *off
 785  * Return found offset in *off. Return ESRCH for end of file.
 786  */
 787 int dmu_offset_next(objset_t *os, uint64_t object, boolean_t hole,
 788     uint64_t *off);
 789 
 790 /*
 791  * Initial setup and final teardown.
 792  */
 793 extern void dmu_init(void);
 794 extern void dmu_fini(void);
 795 
 796 typedef void (*dmu_traverse_cb_t)(objset_t *os, void *arg, struct blkptr *bp,
 797     uint64_t object, uint64_t offset, int len);
 798 void dmu_traverse_objset(objset_t *os, uint64_t txg_start,
 799     dmu_traverse_cb_t cb, void *arg);
 800 
 801 int dmu_diff(const char *tosnap_name, const char *fromsnap_name,
 802     struct vnode *vp, offset_t *offp);
 803 
 804 /* CRC64 table */
 805 #define ZFS_CRC64_POLY  0xC96C5795D7870F42ULL   /* ECMA-182, reflected form */
 806 extern uint64_t zfs_crc64_table[256];
 807 
 808 #ifdef  __cplusplus
 809 }
 810 #endif
 811 
 812 #endif  /* _SYS_DMU_H */