zfs/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
  40 #ifdef  __cplusplus
  41 extern "C" {
  42 #endif
  43
  44 #define IN_DMU_SYNC 2
  45
  46 /*
  47  * define flags for dbuf_read
  48  */
  49
  50 #define DB_RF_MUST_SUCCEED      (1 << 0)
  51 #define DB_RF_CANFAIL           (1 << 1)
  52 #define DB_RF_HAVESTRUCT        (1 << 2)
  53 #define DB_RF_NOPREFETCH        (1 << 3)
  54 #define DB_RF_NEVERWAIT         (1 << 4)
  55 #define DB_RF_CACHED            (1 << 5)
  56
  57 /*
  58  * The simplified state transition diagram for dbufs looks like:
  59  *
  60  *              +----> READ ----+
  61  *              |               |
  62  *              |               V
  63  *  (alloc)-->UNCACHED       CACHED-->EVICTING-->(free)
  64  *              |               ^        ^
  65  *              |               |        |
  66  *              +----> FILL ----+        |
  67  *              |                        |
  68  *              |                        |
  69  *              +--------> NOFILL -------+
  70  *
  71  * DB_SEARCH is an invalid state for a dbuf. It is used by dbuf_free_range
  72  * to find all dbufs in a range of a dnode and must be less than any other
  73  * dbuf_states_t (see comment on dn_dbufs in dnode.h).
  74  */
  75 typedef enum dbuf_states {
  76         DB_SEARCH = -1,
  77         DB_UNCACHED,
  78         DB_FILL,
  79         DB_NOFILL,
  80         DB_READ,
  81         DB_CACHED,
  82         DB_EVICTING
  83 } dbuf_states_t;
  84
  85 struct dnode;
  86 struct dmu_tx;
  87
  88 /*
  89  * level = 0 means the user data
  90  * level = 1 means the single indirect block
  91  * etc.
  92  */
  93
  94 struct dmu_buf_impl;
  95
  96 typedef enum override_states {
  97         DR_NOT_OVERRIDDEN,
  98         DR_IN_DMU_SYNC,
  99         DR_OVERRIDDEN
 100 } override_states_t;
 101
 102 typedef struct dbuf_dirty_record {
 103         /* link on our parents dirty list */
 104         list_node_t dr_dirty_node;
 105
 106         /* transaction group this data will sync in */
 107         uint64_t dr_txg;
 108
 109         /* zio of outstanding write IO */
 110         zio_t *dr_zio;
 111
 112         /* pointer back to our dbuf */
 113         struct dmu_buf_impl *dr_dbuf;
 114
 115         /* pointer to next dirty record */
 116         struct dbuf_dirty_record *dr_next;
 117
 118         /* pointer to parent dirty record */
 119         struct dbuf_dirty_record *dr_parent;
 120
 121         /* How much space was changed to dsl_pool_dirty_space() for this? */
 122         unsigned int dr_accounted;
 123
 124         union dirty_types {
 125                 struct dirty_indirect {
 126
 127                         /* protect access to list */
 128                         kmutex_t dr_mtx;
 129
 130                         /* Our list of dirty children */
 131                         list_t dr_children;
 132                 } di;
 133                 struct dirty_leaf {
 134
 135                         /*
 136                          * dr_data is set when we dirty the buffer
 137                          * so that we can retain the pointer even if it
 138                          * gets COW'd in a subsequent transaction group.
 139                          */
 140                         arc_buf_t *dr_data;
 141                         blkptr_t dr_overridden_by;
 142                         override_states_t dr_override_state;
 143                         uint8_t dr_copies;
 144                         boolean_t dr_nopwrite;
 145                 } dl;
 146         } dt;
 147 } dbuf_dirty_record_t;
 148
 149 typedef struct dmu_buf_impl {
 150         /*
 151          * The following members are immutable, with the exception of
 152          * db.db_data, which is protected by db_mtx.
 153          */
 154
 155         /* the publicly visible structure */
 156         dmu_buf_t db;
 157
 158         /* the objset we belong to */
 159         struct objset *db_objset;
 160
 161         /*
 162          * handle to safely access the dnode we belong to (NULL when evicted)
 163          */
 164         struct dnode_handle *db_dnode_handle;
 165
 166         /*
 167          * our parent buffer; if the dnode points to us directly,
 168          * db_parent == db_dnode_handle->dnh_dnode->dn_dbuf
 169          * only accessed by sync thread ???
 170          * (NULL when evicted)
 171          * May change from NULL to non-NULL under the protection of db_mtx
 172          * (see dbuf_check_blkptr())
 173          */
 174         struct dmu_buf_impl *db_parent;
 175
 176         /*
 177          * link for hash table of all dmu_buf_impl_t's
 178          */
 179         struct dmu_buf_impl *db_hash_next;
 180
 181         /* our block number */
 182         uint64_t db_blkid;
 183
 184         /*
 185          * Pointer to the blkptr_t which points to us. May be NULL if we
 186          * don't have one yet. (NULL when evicted)
 187          */
 188         blkptr_t *db_blkptr;
 189
 190         /*
 191          * Our indirection level.  Data buffers have db_level==0.
 192          * Indirect buffers which point to data buffers have
 193          * db_level==1. etc.  Buffers which contain dnodes have
 194          * db_level==0, since the dnodes are stored in a file.
 195          */
 196         uint8_t db_level;
 197
 198         /* db_mtx protects the members below */
 199         kmutex_t db_mtx;
 200
 201         /*
 202          * Current state of the buffer
 203          */
 204         dbuf_states_t db_state;
 205
 206         /*
 207          * Refcount accessed by dmu_buf_{hold,rele}.
 208          * If nonzero, the buffer can't be destroyed.
 209          * Protected by db_mtx.
 210          */
 211         refcount_t db_holds;
 212
 213         /* buffer holding our data */
 214         arc_buf_t *db_buf;
 215
 216         kcondvar_t db_changed;
 217         dbuf_dirty_record_t *db_data_pending;
 218
 219         /* pointer to most recent dirty record for this buffer */
 220         dbuf_dirty_record_t *db_last_dirty;
 221
 222         /*
 223          * Our link on the owner dnodes's dn_dbufs list.
 224          * Protected by its dn_dbufs_mtx.
 225          */
 226         avl_node_t db_link;
 227
 228         /* Data which is unique to data (leaf) blocks: */
 229
 230         /* User callback information. */
 231         dmu_buf_user_t *db_user;
 232
 233         /*
 234          * Evict user data as soon as the dirty and reference
 235          * counts are equal.
 236          */
 237         uint8_t db_user_immediate_evict;
 238
 239         /*
 240          * This block was freed while a read or write was
 241          * active.
 242          */
 243         uint8_t db_freed_in_flight;
 244
 245         /*
 246          * dnode_evict_dbufs() or dnode_evict_bonus() tried to
 247          * evict this dbuf, but couldn't due to outstanding
 248          * references.  Evict once the refcount drops to 0.
 249          */
 250         uint8_t db_pending_evict;
 251
 252         uint8_t db_dirtycnt;
 253 } dmu_buf_impl_t;
 254
 255 /* Note: the dbuf hash table is exposed only for the mdb module */
 256 #define DBUF_MUTEXES 8192
 257 #define DBUF_HASH_MUTEX(h, idx) (&(h)->hash_mutexes[(idx) & (DBUF_MUTEXES-1)])
 258 typedef struct dbuf_hash_table {
 259         uint64_t hash_table_mask;
 260         dmu_buf_impl_t **hash_table;
 261         kmutex_t hash_mutexes[DBUF_MUTEXES];
 262 } dbuf_hash_table_t;
 263
 264
 265 uint64_t dbuf_whichblock(struct dnode *di, uint64_t offset);
 266
 267 void dbuf_create_bonus(struct dnode *dn);
 268 int dbuf_spill_set_blksz(dmu_buf_t *db, uint64_t blksz, dmu_tx_t *tx);
 269
 270 void dbuf_rm_spill(struct dnode *dn, dmu_tx_t *tx);
 271
 272 dmu_buf_impl_t *dbuf_hold(struct dnode *dn, uint64_t blkid, void *tag);
 273 dmu_buf_impl_t *dbuf_hold_level(struct dnode *dn, int level, uint64_t blkid,
 274     void *tag);
 275 int dbuf_hold_impl(struct dnode *dn, uint8_t level, uint64_t blkid, int create,
 276     void *tag, dmu_buf_impl_t **dbp);
 277
 278 void dbuf_prefetch(struct dnode *dn, uint64_t blkid, zio_priority_t prio);
 279
 280 void dbuf_add_ref(dmu_buf_impl_t *db, void *tag);
 281 boolean_t dbuf_try_add_ref(dmu_buf_t *db, objset_t *os, uint64_t obj,
 282     uint64_t blkid, void *tag);
 283 uint64_t dbuf_refcount(dmu_buf_impl_t *db);
 284
 285 void dbuf_rele(dmu_buf_impl_t *db, void *tag);
 286 void dbuf_rele_and_unlock(dmu_buf_impl_t *db, void *tag);
 287
 288 dmu_buf_impl_t *dbuf_find(struct objset *os, uint64_t object, uint8_t level,
 289     uint64_t blkid);
 290
 291 int dbuf_read(dmu_buf_impl_t *db, zio_t *zio, uint32_t flags);
 292 void dmu_buf_will_not_fill(dmu_buf_t *db, dmu_tx_t *tx);
 293 void dmu_buf_will_fill(dmu_buf_t *db, dmu_tx_t *tx);
 294 void dmu_buf_fill_done(dmu_buf_t *db, dmu_tx_t *tx);
 295 void dbuf_assign_arcbuf(dmu_buf_impl_t *db, arc_buf_t *buf, dmu_tx_t *tx);
 296 dbuf_dirty_record_t *dbuf_dirty(dmu_buf_impl_t *db, dmu_tx_t *tx);
 297 arc_buf_t *dbuf_loan_arcbuf(dmu_buf_impl_t *db);
 298 void dmu_buf_write_embedded(dmu_buf_t *dbuf, void *data,
 299     bp_embedded_type_t etype, enum zio_compress comp,
 300     int uncompressed_size, int compressed_size, int byteorder, dmu_tx_t *tx);
 301
 302 void dbuf_clear(dmu_buf_impl_t *db);
 303 void dbuf_evict(dmu_buf_impl_t *db);
 304
 305 void dbuf_unoverride(dbuf_dirty_record_t *dr);
 306 void dbuf_sync_list(list_t *list, int level, dmu_tx_t *tx);
 307 void dbuf_release_bp(dmu_buf_impl_t *db);
 308
 309 void dbuf_free_range(struct dnode *dn, uint64_t start, uint64_t end,
 310     struct dmu_tx *);
 311
 312 void dbuf_new_size(dmu_buf_impl_t *db, int size, dmu_tx_t *tx);
 313
 314 void dbuf_stats_init(dbuf_hash_table_t *hash);
 315 void dbuf_stats_destroy(void);
 316
 317 #define DB_DNODE(_db)           ((_db)->db_dnode_handle->dnh_dnode)
 318 #define DB_DNODE_LOCK(_db)      ((_db)->db_dnode_handle->dnh_zrlock)
 319 #define DB_DNODE_ENTER(_db)     (zrl_add(&DB_DNODE_LOCK(_db)))
 320 #define DB_DNODE_EXIT(_db)      (zrl_remove(&DB_DNODE_LOCK(_db)))
 321 #define DB_DNODE_HELD(_db)      (!zrl_is_zero(&DB_DNODE_LOCK(_db)))
 322
 323 void dbuf_init(void);
 324 void dbuf_fini(void);
 325
 326 boolean_t dbuf_is_metadata(dmu_buf_impl_t *db);
 327
 328 #define DBUF_GET_BUFC_TYPE(_db) \
 329         (dbuf_is_metadata(_db) ? ARC_BUFC_METADATA : ARC_BUFC_DATA)
 330
 331 #define DBUF_IS_CACHEABLE(_db)                                          \
 332         ((_db)->db_objset->os_primary_cache == ZFS_CACHE_ALL ||         \
 333         (dbuf_is_metadata(_db) &&                                       \
 334         ((_db)->db_objset->os_primary_cache == ZFS_CACHE_METADATA)))
 335
 336 #define DBUF_IS_L2CACHEABLE(_db)                                        \
 337         ((_db)->db_objset->os_secondary_cache == ZFS_CACHE_ALL ||       \
 338         (dbuf_is_metadata(_db) &&                                       \
 339         ((_db)->db_objset->os_secondary_cache == ZFS_CACHE_METADATA)))
 340
 341 #define DBUF_IS_L2COMPRESSIBLE(_db)                                     \
 342         ((_db)->db_objset->os_compress != ZIO_COMPRESS_OFF ||           \
 343         (dbuf_is_metadata(_db) && zfs_mdcomp_disable == B_FALSE))
 344
 345 #ifdef ZFS_DEBUG
 346
 347 /*
 348  * There should be a ## between the string literal and fmt, to make it
 349  * clear that we're joining two strings together, but gcc does not
 350  * support that preprocessor token.
 351  */
 352 #define dprintf_dbuf(dbuf, fmt, ...) do { \
 353         if (zfs_flags & ZFS_DEBUG_DPRINTF) { \
 354         char __db_buf[32]; \
 355         uint64_t __db_obj = (dbuf)->db.db_object; \
 356         if (__db_obj == DMU_META_DNODE_OBJECT) \
 357                 (void) strcpy(__db_buf, "mdn"); \
 358         else \
 359                 (void) snprintf(__db_buf, sizeof (__db_buf), "%lld", \
 360                     (u_longlong_t)__db_obj); \
 361         dprintf_ds((dbuf)->db_objset->os_dsl_dataset, \
 362             "obj=%s lvl=%u blkid=%lld " fmt, \
 363             __db_buf, (dbuf)->db_level, \
 364             (u_longlong_t)(dbuf)->db_blkid, __VA_ARGS__); \
 365         } \
 366 _NOTE(CONSTCOND) } while (0)
 367
 368 #define dprintf_dbuf_bp(db, bp, fmt, ...) do {                  \
 369         if (zfs_flags & ZFS_DEBUG_DPRINTF) {                    \
 370         char *__blkbuf = kmem_alloc(BP_SPRINTF_LEN, KM_SLEEP);  \
 371         snprintf_blkptr(__blkbuf, BP_SPRINTF_LEN, bp);          \
 372         dprintf_dbuf(db, fmt " %s\n", __VA_ARGS__, __blkbuf);   \
 373         kmem_free(__blkbuf, BP_SPRINTF_LEN);                    \
 374         }                                                       \
 375 _NOTE(CONSTCOND) } while (0)
 376
 377 #define DBUF_VERIFY(db) dbuf_verify(db)
 378
 379 #else
 380
 381 #define dprintf_dbuf(db, fmt, ...)
 382 #define dprintf_dbuf_bp(db, bp, fmt, ...)
 383 #define DBUF_VERIFY(db)
 384
 385 #endif
 386
 387
 388 #ifdef  __cplusplus
 389 }
 390 #endif
 391
 392 #endif /* _SYS_DBUF_H */