include/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 struct dnode;
  87 struct dmu_tx;
  88
  89 /*
  90  * level = 0 means the user data
  91  * level = 1 means the single indirect block
  92  * etc.
  93  */
  94
  95 struct dmu_buf_impl;
  96
  97 typedef enum override_states {
  98         DR_NOT_OVERRIDDEN,
  99         DR_IN_DMU_SYNC,
 100         DR_OVERRIDDEN
 101 } override_states_t;
 102
 103 typedef struct dbuf_dirty_record {
 104         /* link on our parents dirty list */
 105         list_node_t dr_dirty_node;
 106
 107         /* transaction group this data will sync in */
 108         uint64_t dr_txg;
 109
 110         /* zio of outstanding write IO */
 111         zio_t *dr_zio;
 112
 113         /* pointer back to our dbuf */
 114         struct dmu_buf_impl *dr_dbuf;
 115
 116         /* pointer to next dirty record */
 117         struct dbuf_dirty_record *dr_next;
 118
 119         /* pointer to parent dirty record */
 120         struct dbuf_dirty_record *dr_parent;
 121
 122         /* How much space was changed to dsl_pool_dirty_space() for this? */
 123         unsigned int dr_accounted;
 124
 125         /* A copy of the bp that points to us */
 126         blkptr_t dr_bp_copy;
 127
 128         union dirty_types {
 129                 struct dirty_indirect {
 130
 131                         /* protect access to list */
 132                         kmutex_t dr_mtx;
 133
 134                         /* Our list of dirty children */
 135                         list_t dr_children;
 136                 } di;
 137                 struct dirty_leaf {
 138
 139                         /*
 140                          * dr_data is set when we dirty the buffer
 141                          * so that we can retain the pointer even if it
 142                          * gets COW'd in a subsequent transaction group.
 143                          */
 144                         arc_buf_t *dr_data;
 145                         blkptr_t dr_overridden_by;
 146                         override_states_t dr_override_state;
 147                         uint8_t dr_copies;
 148                         boolean_t dr_nopwrite;
 149                 } dl;
 150         } dt;
 151 } dbuf_dirty_record_t;
 152
 153 typedef struct dmu_buf_impl {
 154         /*
 155          * The following members are immutable, with the exception of
 156          * db.db_data, which is protected by db_mtx.
 157          */
 158
 159         /* the publicly visible structure */
 160         dmu_buf_t db;
 161
 162         /* the objset we belong to */
 163         struct objset *db_objset;
 164
 165         /*
 166          * handle to safely access the dnode we belong to (NULL when evicted)
 167          */
 168         struct dnode_handle *db_dnode_handle;
 169
 170         /*
 171          * our parent buffer; if the dnode points to us directly,
 172          * db_parent == db_dnode_handle->dnh_dnode->dn_dbuf
 173          * only accessed by sync thread ???
 174          * (NULL when evicted)
 175          * May change from NULL to non-NULL under the protection of db_mtx
 176          * (see dbuf_check_blkptr())
 177          */
 178         struct dmu_buf_impl *db_parent;
 179
 180         /*
 181          * link for hash table of all dmu_buf_impl_t's
 182          */
 183         struct dmu_buf_impl *db_hash_next;
 184
 185         /* our block number */
 186         uint64_t db_blkid;
 187
 188         /*
 189          * Pointer to the blkptr_t which points to us. May be NULL if we
 190          * don't have one yet. (NULL when evicted)
 191          */
 192         blkptr_t *db_blkptr;
 193
 194         /*
 195          * Our indirection level.  Data buffers have db_level==0.
 196          * Indirect buffers which point to data buffers have
 197          * db_level==1. etc.  Buffers which contain dnodes have
 198          * db_level==0, since the dnodes are stored in a file.
 199          */
 200         uint8_t db_level;
 201
 202         /* db_mtx protects the members below */
 203         kmutex_t db_mtx;
 204
 205         /*
 206          * Current state of the buffer
 207          */
 208         dbuf_states_t db_state;
 209
 210         /*
 211          * Refcount accessed by dmu_buf_{hold,rele}.
 212          * If nonzero, the buffer can't be destroyed.
 213          * Protected by db_mtx.
 214          */
 215         refcount_t db_holds;
 216
 217         /* buffer holding our data */
 218         arc_buf_t *db_buf;
 219
 220         kcondvar_t db_changed;
 221         dbuf_dirty_record_t *db_data_pending;
 222
 223         /* pointer to most recent dirty record for this buffer */
 224         dbuf_dirty_record_t *db_last_dirty;
 225
 226         /*
 227          * Our link on the owner dnodes's dn_dbufs list.
 228          * Protected by its dn_dbufs_mtx.
 229          */
 230         avl_node_t db_link;
 231
 232         /*
 233          * Link in dbuf_cache.
 234          */
 235         multilist_node_t db_cache_link;
 236
 237         /* Data which is unique to data (leaf) blocks: */
 238
 239         /* User callback information. */
 240         dmu_buf_user_t *db_user;
 241
 242         /*
 243          * Evict user data as soon as the dirty and reference
 244          * counts are equal.
 245          */
 246         uint8_t db_user_immediate_evict;
 247
 248         /*
 249          * This block was freed while a read or write was
 250          * active.
 251          */
 252         uint8_t db_freed_in_flight;
 253
 254         /*
 255          * dnode_evict_dbufs() or dnode_evict_bonus() tried to
 256          * evict this dbuf, but couldn't due to outstanding
 257          * references.  Evict once the refcount drops to 0.
 258          */
 259         uint8_t db_pending_evict;
 260
 261         uint8_t db_dirtycnt;
 262 } dmu_buf_impl_t;
 263
 264 /* Note: the dbuf hash table is exposed only for the mdb module */
 265 #define DBUF_MUTEXES 8192
 266 #define DBUF_HASH_MUTEX(h, idx) (&(h)->hash_mutexes[(idx) & (DBUF_MUTEXES-1)])
 267 typedef struct dbuf_hash_table {
 268         uint64_t hash_table_mask;
 269         dmu_buf_impl_t **hash_table;
 270         kmutex_t hash_mutexes[DBUF_MUTEXES];
 271 } dbuf_hash_table_t;
 272
 273 uint64_t dbuf_whichblock(const struct dnode *di, const int64_t level,
 274     const uint64_t offset);
 275
 276 void dbuf_create_bonus(struct dnode *dn);
 277 int dbuf_spill_set_blksz(dmu_buf_t *db, uint64_t blksz, dmu_tx_t *tx);
 278
 279 void dbuf_rm_spill(struct dnode *dn, dmu_tx_t *tx);
 280
 281 dmu_buf_impl_t *dbuf_hold(struct dnode *dn, uint64_t blkid, void *tag);
 282 dmu_buf_impl_t *dbuf_hold_level(struct dnode *dn, int level, uint64_t blkid,
 283     void *tag);
 284 int dbuf_hold_impl(struct dnode *dn, uint8_t level, uint64_t blkid,
 285     boolean_t fail_sparse, boolean_t fail_uncached,
 286     void *tag, dmu_buf_impl_t **dbp);
 287
 288 void dbuf_prefetch(struct dnode *dn, int64_t level, uint64_t blkid,
 289     zio_priority_t prio, arc_flags_t aflags);
 290
 291 void dbuf_add_ref(dmu_buf_impl_t *db, void *tag);
 292 boolean_t dbuf_try_add_ref(dmu_buf_t *db, objset_t *os, uint64_t obj,
 293     uint64_t blkid, void *tag);
 294 uint64_t dbuf_refcount(dmu_buf_impl_t *db);
 295
 296 void dbuf_rele(dmu_buf_impl_t *db, void *tag);
 297 void dbuf_rele_and_unlock(dmu_buf_impl_t *db, void *tag);
 298
 299 dmu_buf_impl_t *dbuf_find(struct objset *os, uint64_t object, uint8_t level,
 300     uint64_t blkid);
 301
 302 int dbuf_read(dmu_buf_impl_t *db, zio_t *zio, uint32_t flags);
 303 void dmu_buf_will_not_fill(dmu_buf_t *db, dmu_tx_t *tx);
 304 void dmu_buf_will_fill(dmu_buf_t *db, dmu_tx_t *tx);
 305 void dmu_buf_fill_done(dmu_buf_t *db, dmu_tx_t *tx);
 306 void dbuf_assign_arcbuf(dmu_buf_impl_t *db, arc_buf_t *buf, dmu_tx_t *tx);
 307 dbuf_dirty_record_t *dbuf_dirty(dmu_buf_impl_t *db, dmu_tx_t *tx);
 308 arc_buf_t *dbuf_loan_arcbuf(dmu_buf_impl_t *db);
 309 void dmu_buf_write_embedded(dmu_buf_t *dbuf, void *data,
 310     bp_embedded_type_t etype, enum zio_compress comp,
 311     int uncompressed_size, int compressed_size, int byteorder, dmu_tx_t *tx);
 312
 313 void dbuf_destroy(dmu_buf_impl_t *db);
 314
 315 void dbuf_unoverride(dbuf_dirty_record_t *dr);
 316 void dbuf_sync_list(list_t *list, int level, dmu_tx_t *tx);
 317 void dbuf_release_bp(dmu_buf_impl_t *db);
 318
 319 void dbuf_free_range(struct dnode *dn, uint64_t start, uint64_t end,
 320     struct dmu_tx *);
 321
 322 void dbuf_new_size(dmu_buf_impl_t *db, int size, dmu_tx_t *tx);
 323
 324 void dbuf_stats_init(dbuf_hash_table_t *hash);
 325 void dbuf_stats_destroy(void);
 326
 327 #define DB_DNODE(_db)           ((_db)->db_dnode_handle->dnh_dnode)
 328 #define DB_DNODE_LOCK(_db)      ((_db)->db_dnode_handle->dnh_zrlock)
 329 #define DB_DNODE_ENTER(_db)     (zrl_add(&DB_DNODE_LOCK(_db)))
 330 #define DB_DNODE_EXIT(_db)      (zrl_remove(&DB_DNODE_LOCK(_db)))
 331 #define DB_DNODE_HELD(_db)      (!zrl_is_zero(&DB_DNODE_LOCK(_db)))
 332
 333 void dbuf_init(void);
 334 void dbuf_fini(void);
 335
 336 boolean_t dbuf_is_metadata(dmu_buf_impl_t *db);
 337
 338 #define DBUF_GET_BUFC_TYPE(_db) \
 339         (dbuf_is_metadata(_db) ? ARC_BUFC_METADATA : ARC_BUFC_DATA)
 340
 341 #define DBUF_IS_CACHEABLE(_db)                                          \
 342         ((_db)->db_objset->os_primary_cache == ZFS_CACHE_ALL ||         \
 343         (dbuf_is_metadata(_db) &&                                       \
 344         ((_db)->db_objset->os_primary_cache == ZFS_CACHE_METADATA)))
 345
 346 #define DBUF_IS_L2CACHEABLE(_db)                                        \
 347         ((_db)->db_objset->os_secondary_cache == ZFS_CACHE_ALL ||       \
 348         (dbuf_is_metadata(_db) &&                                       \
 349         ((_db)->db_objset->os_secondary_cache == ZFS_CACHE_METADATA)))
 350
 351 #ifdef ZFS_DEBUG
 352
 353 /*
 354  * There should be a ## between the string literal and fmt, to make it
 355  * clear that we're joining two strings together, but gcc does not
 356  * support that preprocessor token.
 357  */
 358 #define dprintf_dbuf(dbuf, fmt, ...) do { \
 359         if (zfs_flags & ZFS_DEBUG_DPRINTF) { \
 360         char __db_buf[32]; \
 361         uint64_t __db_obj = (dbuf)->db.db_object; \
 362         if (__db_obj == DMU_META_DNODE_OBJECT) \
 363                 (void) strcpy(__db_buf, "mdn"); \
 364         else \
 365                 (void) snprintf(__db_buf, sizeof (__db_buf), "%lld", \
 366                     (u_longlong_t)__db_obj); \
 367         dprintf_ds((dbuf)->db_objset->os_dsl_dataset, \
 368             "obj=%s lvl=%u blkid=%lld " fmt, \
 369             __db_buf, (dbuf)->db_level, \
 370             (u_longlong_t)(dbuf)->db_blkid, __VA_ARGS__); \
 371         } \
 372 _NOTE(CONSTCOND) } while (0)
 373
 374 #define dprintf_dbuf_bp(db, bp, fmt, ...) do {                  \
 375         if (zfs_flags & ZFS_DEBUG_DPRINTF) {                    \
 376         char *__blkbuf = kmem_alloc(BP_SPRINTF_LEN, KM_SLEEP);  \
 377         snprintf_blkptr(__blkbuf, BP_SPRINTF_LEN, bp);          \
 378         dprintf_dbuf(db, fmt " %s\n", __VA_ARGS__, __blkbuf);   \
 379         kmem_free(__blkbuf, BP_SPRINTF_LEN);                    \
 380         }                                                       \
 381 _NOTE(CONSTCOND) } while (0)
 382
 383 #define DBUF_VERIFY(db) dbuf_verify(db)
 384
 385 #else
 386
 387 #define dprintf_dbuf(db, fmt, ...)
 388 #define dprintf_dbuf_bp(db, bp, fmt, ...)
 389 #define DBUF_VERIFY(db)
 390
 391 #endif
 392
 393
 394 #ifdef  __cplusplus
 395 }
 396 #endif
 397
 398 #endif /* _SYS_DBUF_H */