usr/src/uts/common/fs/zfs/sys/dbuf.h

   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  * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
  23  * Copyright (c) 2012, 2015 by Delphix. All rights reserved.
  24  * Copyright (c) 2013 by Saso Kiselkov. All rights reserved.
  25  * Copyright (c) 2014 Spectra Logic Corporation, All rights reserved.
  26  */
  27
  28 #ifndef _SYS_DBUF_H
  29 #define _SYS_DBUF_H
  30
  31 #include <sys/dmu.h>
  32 #include <sys/spa.h>
  33 #include <sys/txg.h>
  34 #include <sys/zio.h>
  35 #include <sys/arc.h>
  36 #include <sys/zfs_context.h>
  37 #include <sys/refcount.h>
  38 #include <sys/zrlock.h>
  39 #include <sys/multilist.h>
  40
  41 #ifdef  __cplusplus
  42 extern "C" {
  43 #endif
  44
  45 #define IN_DMU_SYNC 2
  46
  47 /*
  48  * define flags for dbuf_read
  49  */
  50
  51 #define DB_RF_MUST_SUCCEED      (1 << 0)
  52 #define DB_RF_CANFAIL           (1 << 1)
  53 #define DB_RF_HAVESTRUCT        (1 << 2)
  54 #define DB_RF_NOPREFETCH        (1 << 3)
  55 #define DB_RF_NEVERWAIT         (1 << 4)
  56 #define DB_RF_CACHED            (1 << 5)
  57
  58 /*
  59  * The simplified state transition diagram for dbufs looks like:
  60  *
  61  *              +----> READ ----+
  62  *              |               |
  63  *              |               V
  64  *  (alloc)-->UNCACHED       CACHED-->EVICTING-->(free)
  65  *              |               ^        ^
  66  *              |               |        |
  67  *              +----> FILL ----+        |
  68  *              |                        |
  69  *              |                        |
  70  *              +--------> NOFILL -------+
  71  *
  72  * DB_SEARCH is an invalid state for a dbuf. It is used by dbuf_free_range
  73  * to find all dbufs in a range of a dnode and must be less than any other
  74  * dbuf_states_t (see comment on dn_dbufs in dnode.h).
  75  */
  76 typedef enum dbuf_states {
  77         DB_SEARCH = -1,
  78         DB_UNCACHED,
  79         DB_FILL,
  80         DB_NOFILL,
  81         DB_READ,
  82         DB_CACHED,
  83         DB_EVICTING
  84 } dbuf_states_t;
  85
  86 typedef enum dbuf_cached_state {
  87         DB_NO_CACHE = -1,
  88         DB_DBUF_CACHE,
  89         DB_DBUF_METADATA_CACHE,
  90         DB_CACHE_MAX
  91 } dbuf_cached_state_t;
  92
  93 struct dnode;
  94 struct dmu_tx;
  95
  96 /*
  97  * level = 0 means the user data
  98  * level = 1 means the single indirect block
  99  * etc.
 100  */
 101
 102 struct dmu_buf_impl;
 103
 104 typedef enum override_states {
 105         DR_NOT_OVERRIDDEN,
 106         DR_IN_DMU_SYNC,
 107         DR_OVERRIDDEN
 108 } override_states_t;
 109
 110 typedef struct dbuf_dirty_record {
 111         /* link on our parents dirty list */
 112         list_node_t dr_dirty_node;
 113
 114         /* transaction group this data will sync in */
 115         uint64_t dr_txg;
 116
 117         /* zio of outstanding write IO */
 118         zio_t *dr_zio;
 119
 120         /* pointer back to our dbuf */
 121         struct dmu_buf_impl *dr_dbuf;
 122
 123         /* pointer to next dirty record */
 124         struct dbuf_dirty_record *dr_next;
 125
 126         /* pointer to parent dirty record */
 127         struct dbuf_dirty_record *dr_parent;
 128
 129         /* How much space was changed to dsl_pool_dirty_space() for this? */
 130         unsigned int dr_accounted;
 131
 132         /* A copy of the bp that points to us */
 133         blkptr_t dr_bp_copy;
 134
 135         union dirty_types {
 136                 struct dirty_indirect {
 137
 138                         /* protect access to list */
 139                         kmutex_t dr_mtx;
 140
 141                         /* Our list of dirty children */
 142                         list_t dr_children;
 143                 } di;
 144                 struct dirty_leaf {
 145
 146                         /*
 147                          * dr_data is set when we dirty the buffer
 148                          * so that we can retain the pointer even if it
 149                          * gets COW'd in a subsequent transaction group.
 150                          */
 151                         arc_buf_t *dr_data;
 152                         blkptr_t dr_overridden_by;
 153                         override_states_t dr_override_state;
 154                         uint8_t dr_copies;
 155                         boolean_t dr_nopwrite;
 156                 } dl;
 157         } dt;
 158 } dbuf_dirty_record_t;
 159
 160 typedef struct dmu_buf_impl {
 161         /*
 162          * The following members are immutable, with the exception of
 163          * db.db_data, which is protected by db_mtx.
 164          */
 165
 166         /* the publicly visible structure */
 167         dmu_buf_t db;
 168
 169         /* the objset we belong to */
 170         struct objset *db_objset;
 171
 172         /*
 173          * handle to safely access the dnode we belong to (NULL when evicted)
 174          */
 175         struct dnode_handle *db_dnode_handle;
 176
 177         /*
 178          * our parent buffer; if the dnode points to us directly,
 179          * db_parent == db_dnode_handle->dnh_dnode->dn_dbuf
 180          * only accessed by sync thread ???
 181          * (NULL when evicted)
 182          * May change from NULL to non-NULL under the protection of db_mtx
 183          * (see dbuf_check_blkptr())
 184          */
 185         struct dmu_buf_impl *db_parent;
 186
 187         /*
 188          * link for hash table of all dmu_buf_impl_t's
 189          */
 190         struct dmu_buf_impl *db_hash_next;
 191
 192         /* our block number */
 193         uint64_t db_blkid;
 194
 195         /*
 196          * Pointer to the blkptr_t which points to us. May be NULL if we
 197          * don't have one yet. (NULL when evicted)
 198          */
 199         blkptr_t *db_blkptr;
 200
 201         /*
 202          * Our indirection level.  Data buffers have db_level==0.
 203          * Indirect buffers which point to data buffers have
 204          * db_level==1. etc.  Buffers which contain dnodes have
 205          * db_level==0, since the dnodes are stored in a file.
 206          */
 207         uint8_t db_level;
 208
 209         /* db_mtx protects the members below */
 210         kmutex_t db_mtx;
 211
 212         /*
 213          * Current state of the buffer
 214          */
 215         dbuf_states_t db_state;
 216
 217         /*
 218          * Refcount accessed by dmu_buf_{hold,rele}.
 219          * If nonzero, the buffer can't be destroyed.
 220          * Protected by db_mtx.
 221          */
 222         refcount_t db_holds;
 223
 224         /* buffer holding our data */
 225         arc_buf_t *db_buf;
 226
 227         kcondvar_t db_changed;
 228         dbuf_dirty_record_t *db_data_pending;
 229
 230         /* pointer to most recent dirty record for this buffer */
 231         dbuf_dirty_record_t *db_last_dirty;
 232
 233         /*
 234          * Our link on the owner dnodes's dn_dbufs list.
 235          * Protected by its dn_dbufs_mtx.
 236          */
 237         avl_node_t db_link;
 238
 239         /* Link in dbuf_cache or dbuf_metadata_cache */
 240         multilist_node_t db_cache_link;
 241
 242         /* Tells us which dbuf cache this dbuf is in, if any */
 243         dbuf_cached_state_t db_caching_status;
 244
 245         /* Data which is unique to data (leaf) blocks: */
 246
 247         /* User callback information. */
 248         dmu_buf_user_t *db_user;
 249
 250         /*
 251          * Evict user data as soon as the dirty and reference
 252          * counts are equal.
 253          */
 254         uint8_t db_user_immediate_evict;
 255
 256         /*
 257          * This block was freed while a read or write was
 258          * active.
 259          */
 260         uint8_t db_freed_in_flight;
 261
 262         /*
 263          * dnode_evict_dbufs() or dnode_evict_bonus() tried to
 264          * evict this dbuf, but couldn't due to outstanding
 265          * references.  Evict once the refcount drops to 0.
 266          */
 267         uint8_t db_pending_evict;
 268
 269         uint8_t db_dirtycnt;
 270 } dmu_buf_impl_t;
 271
 272 /* Note: the dbuf hash table is exposed only for the mdb module */
 273 #define DBUF_MUTEXES 256
 274 #define DBUF_HASH_MUTEX(h, idx) (&(h)->hash_mutexes[(idx) & (DBUF_MUTEXES-1)])
 275 typedef struct dbuf_hash_table {
 276         uint64_t hash_table_mask;
 277         dmu_buf_impl_t **hash_table;
 278         kmutex_t hash_mutexes[DBUF_MUTEXES];
 279 } dbuf_hash_table_t;
 280
 281 uint64_t dbuf_whichblock(struct dnode *di, int64_t level, uint64_t offset);
 282
 283 dmu_buf_impl_t *dbuf_create_tlib(struct dnode *dn, char *data);
 284 void dbuf_create_bonus(struct dnode *dn);
 285 int dbuf_spill_set_blksz(dmu_buf_t *db, uint64_t blksz, dmu_tx_t *tx);
 286 void dbuf_spill_hold(struct dnode *dn, dmu_buf_impl_t **dbp, void *tag);
 287
 288 void dbuf_rm_spill(struct dnode *dn, dmu_tx_t *tx);
 289
 290 dmu_buf_impl_t *dbuf_hold(struct dnode *dn, uint64_t blkid, void *tag);
 291 dmu_buf_impl_t *dbuf_hold_level(struct dnode *dn, int level, uint64_t blkid,
 292     void *tag);
 293 int dbuf_hold_impl(struct dnode *dn, uint8_t level, uint64_t blkid,
 294     boolean_t fail_sparse, boolean_t fail_uncached,
 295     void *tag, dmu_buf_impl_t **dbp);
 296
 297 void dbuf_prefetch(struct dnode *dn, int64_t level, uint64_t blkid,
 298     zio_priority_t prio, arc_flags_t aflags);
 299
 300 void dbuf_add_ref(dmu_buf_impl_t *db, void *tag);
 301 boolean_t dbuf_try_add_ref(dmu_buf_t *db, objset_t *os, uint64_t obj,
 302     uint64_t blkid, void *tag);
 303 uint64_t dbuf_refcount(dmu_buf_impl_t *db);
 304
 305 void dbuf_rele(dmu_buf_impl_t *db, void *tag);
 306 void dbuf_rele_and_unlock(dmu_buf_impl_t *db, void *tag);
 307
 308 dmu_buf_impl_t *dbuf_find(struct objset *os, uint64_t object, uint8_t level,
 309     uint64_t blkid);
 310
 311 int dbuf_read(dmu_buf_impl_t *db, zio_t *zio, uint32_t flags);
 312 void dmu_buf_will_not_fill(dmu_buf_t *db, dmu_tx_t *tx);
 313 void dmu_buf_will_fill(dmu_buf_t *db, dmu_tx_t *tx);
 314 void dmu_buf_fill_done(dmu_buf_t *db, dmu_tx_t *tx);
 315 void dbuf_assign_arcbuf(dmu_buf_impl_t *db, arc_buf_t *buf, dmu_tx_t *tx);
 316 dbuf_dirty_record_t *dbuf_dirty(dmu_buf_impl_t *db, dmu_tx_t *tx);
 317 arc_buf_t *dbuf_loan_arcbuf(dmu_buf_impl_t *db);
 318 void dmu_buf_write_embedded(dmu_buf_t *dbuf, void *data,
 319     bp_embedded_type_t etype, enum zio_compress comp,
 320     int uncompressed_size, int compressed_size, int byteorder, dmu_tx_t *tx);
 321
 322 void dbuf_destroy(dmu_buf_impl_t *db);
 323
 324 void dbuf_setdirty(dmu_buf_impl_t *db, dmu_tx_t *tx);
 325 void dbuf_unoverride(dbuf_dirty_record_t *dr);
 326 void dbuf_sync_list(list_t *list, int level, dmu_tx_t *tx);
 327 void dbuf_release_bp(dmu_buf_impl_t *db);
 328
 329 boolean_t dbuf_can_remap(const dmu_buf_impl_t *buf);
 330
 331 void dbuf_free_range(struct dnode *dn, uint64_t start, uint64_t end,
 332     struct dmu_tx *);
 333
 334 void dbuf_new_size(dmu_buf_impl_t *db, int size, dmu_tx_t *tx);
 335
 336 #define DB_DNODE(_db)           ((_db)->db_dnode_handle->dnh_dnode)
 337 #define DB_DNODE_LOCK(_db)      ((_db)->db_dnode_handle->dnh_zrlock)
 338 #define DB_DNODE_ENTER(_db)     (zrl_add(&DB_DNODE_LOCK(_db)))
 339 #define DB_DNODE_EXIT(_db)      (zrl_remove(&DB_DNODE_LOCK(_db)))
 340 #define DB_DNODE_HELD(_db)      (!zrl_is_zero(&DB_DNODE_LOCK(_db)))
 341
 342 void dbuf_init(void);
 343 void dbuf_fini(void);
 344
 345 boolean_t dbuf_is_metadata(dmu_buf_impl_t *db);
 346
 347 #define DBUF_GET_BUFC_TYPE(_db) \
 348         (dbuf_is_metadata(_db) ? ARC_BUFC_METADATA : ARC_BUFC_DATA)
 349
 350 #define DBUF_IS_CACHEABLE(_db)                                          \
 351         ((_db)->db_objset->os_primary_cache == ZFS_CACHE_ALL ||         \
 352         (dbuf_is_metadata(_db) &&                                       \
 353         ((_db)->db_objset->os_primary_cache == ZFS_CACHE_METADATA)))
 354
 355 #define DBUF_IS_L2CACHEABLE(_db)                                        \
 356         ((_db)->db_objset->os_secondary_cache == ZFS_CACHE_ALL ||       \
 357         (dbuf_is_metadata(_db) &&                                       \
 358         ((_db)->db_objset->os_secondary_cache == ZFS_CACHE_METADATA)))
 359
 360 #define DNODE_LEVEL_IS_L2CACHEABLE(_dn, _level)                         \
 361         ((_dn)->dn_objset->os_secondary_cache == ZFS_CACHE_ALL ||       \
 362         (((_level) > 0 ||                                               \
 363         DMU_OT_IS_METADATA((_dn)->dn_handle->dnh_dnode->dn_type)) &&    \
 364         ((_dn)->dn_objset->os_secondary_cache == ZFS_CACHE_METADATA)))
 365
 366 #ifdef ZFS_DEBUG
 367
 368 /*
 369  * There should be a ## between the string literal and fmt, to make it
 370  * clear that we're joining two strings together, but gcc does not
 371  * support that preprocessor token.
 372  */
 373 #define dprintf_dbuf(dbuf, fmt, ...) do { \
 374         if (zfs_flags & ZFS_DEBUG_DPRINTF) { \
 375         char __db_buf[32]; \
 376         uint64_t __db_obj = (dbuf)->db.db_object; \
 377         if (__db_obj == DMU_META_DNODE_OBJECT) \
 378                 (void) strcpy(__db_buf, "mdn"); \
 379         else \
 380                 (void) snprintf(__db_buf, sizeof (__db_buf), "%lld", \
 381                     (u_longlong_t)__db_obj); \
 382         dprintf_ds((dbuf)->db_objset->os_dsl_dataset, \
 383             "obj=%s lvl=%u blkid=%lld " fmt, \
 384             __db_buf, (dbuf)->db_level, \
 385             (u_longlong_t)(dbuf)->db_blkid, __VA_ARGS__); \
 386         } \
 387 _NOTE(CONSTCOND) } while (0)
 388
 389 #define dprintf_dbuf_bp(db, bp, fmt, ...) do {                  \
 390         if (zfs_flags & ZFS_DEBUG_DPRINTF) {                    \
 391         char *__blkbuf = kmem_alloc(BP_SPRINTF_LEN, KM_SLEEP);  \
 392         snprintf_blkptr(__blkbuf, BP_SPRINTF_LEN, bp);          \
 393         dprintf_dbuf(db, fmt " %s\n", __VA_ARGS__, __blkbuf);   \
 394         kmem_free(__blkbuf, BP_SPRINTF_LEN);                    \
 395         }                                                       \
 396 _NOTE(CONSTCOND) } while (0)
 397
 398 #define DBUF_VERIFY(db) dbuf_verify(db)
 399
 400 #else
 401
 402 #define dprintf_dbuf(db, fmt, ...)
 403 #define dprintf_dbuf_bp(db, bp, fmt, ...)
 404 #define DBUF_VERIFY(db)
 405
 406 #endif
 407
 408
 409 #ifdef  __cplusplus
 410 }
 411 #endif
 412
 413 #endif /* _SYS_DBUF_H */