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
  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         /* A copy of the bp that points to us */
 125         blkptr_t dr_bp_copy;
 126
 127         union dirty_types {
 128                 struct dirty_indirect {
 129
 130                         /* protect access to list */
 131                         kmutex_t dr_mtx;
 132
 133                         /* Our list of dirty children */
 134                         list_t dr_children;
 135                 } di;
 136                 struct dirty_leaf {
 137
 138                         /*
 139                          * dr_data is set when we dirty the buffer
 140                          * so that we can retain the pointer even if it
 141                          * gets COW'd in a subsequent transaction group.
 142                          */
 143                         arc_buf_t *dr_data;
 144                         blkptr_t dr_overridden_by;
 145                         override_states_t dr_override_state;
 146                         uint8_t dr_copies;
 147                         boolean_t dr_nopwrite;
 148                 } dl;
 149         } dt;
 150 } dbuf_dirty_record_t;
 151
 152 typedef struct dmu_buf_impl {
 153         /*
 154          * The following members are immutable, with the exception of
 155          * db.db_data, which is protected by db_mtx.
 156          */
 157
 158         /* the publicly visible structure */
 159         dmu_buf_t db;
 160
 161         /* the objset we belong to */
 162         struct objset *db_objset;
 163
 164         /*
 165          * handle to safely access the dnode we belong to (NULL when evicted)
 166          */
 167         struct dnode_handle *db_dnode_handle;
 168
 169         /*
 170          * our parent buffer; if the dnode points to us directly,
 171          * db_parent == db_dnode_handle->dnh_dnode->dn_dbuf
 172          * only accessed by sync thread ???
 173          * (NULL when evicted)
 174          * May change from NULL to non-NULL under the protection of db_mtx
 175          * (see dbuf_check_blkptr())
 176          */
 177         struct dmu_buf_impl *db_parent;
 178
 179         /*
 180          * link for hash table of all dmu_buf_impl_t's
 181          */
 182         struct dmu_buf_impl *db_hash_next;
 183
 184         /* our block number */
 185         uint64_t db_blkid;
 186
 187         /*
 188          * Pointer to the blkptr_t which points to us. May be NULL if we
 189          * don't have one yet. (NULL when evicted)
 190          */
 191         blkptr_t *db_blkptr;
 192
 193         /*
 194          * Our indirection level.  Data buffers have db_level==0.
 195          * Indirect buffers which point to data buffers have
 196          * db_level==1. etc.  Buffers which contain dnodes have
 197          * db_level==0, since the dnodes are stored in a file.
 198          */
 199         uint8_t db_level;
 200
 201         /* db_mtx protects the members below */
 202         kmutex_t db_mtx;
 203
 204         /*
 205          * Current state of the buffer
 206          */
 207         dbuf_states_t db_state;
 208
 209         /*
 210          * Refcount accessed by dmu_buf_{hold,rele}.
 211          * If nonzero, the buffer can't be destroyed.
 212          * Protected by db_mtx.
 213          */
 214         refcount_t db_holds;
 215
 216         /* buffer holding our data */
 217         arc_buf_t *db_buf;
 218
 219         kcondvar_t db_changed;
 220         dbuf_dirty_record_t *db_data_pending;
 221
 222         /* pointer to most recent dirty record for this buffer */
 223         dbuf_dirty_record_t *db_last_dirty;
 224
 225         /*
 226          * Our link on the owner dnodes's dn_dbufs list.
 227          * Protected by its dn_dbufs_mtx.
 228          */
 229         avl_node_t db_link;
 230
 231         /* Data which is unique to data (leaf) blocks: */
 232
 233         /* User callback information. */
 234         dmu_buf_user_t *db_user;
 235
 236         /*
 237          * Evict user data as soon as the dirty and reference
 238          * counts are equal.
 239          */
 240         uint8_t db_user_immediate_evict;
 241
 242         /*
 243          * This block was freed while a read or write was
 244          * active.
 245          */
 246         uint8_t db_freed_in_flight;
 247
 248         /*
 249          * dnode_evict_dbufs() or dnode_evict_bonus() tried to
 250          * evict this dbuf, but couldn't due to outstanding
 251          * references.  Evict once the refcount drops to 0.
 252          */
 253         uint8_t db_pending_evict;
 254
 255         uint8_t db_dirtycnt;
 256 } dmu_buf_impl_t;
 257
 258 /* Note: the dbuf hash table is exposed only for the mdb module */
 259 #define DBUF_MUTEXES 256
 260 #define DBUF_HASH_MUTEX(h, idx) (&(h)->hash_mutexes[(idx) & (DBUF_MUTEXES-1)])
 261 typedef struct dbuf_hash_table {
 262         uint64_t hash_table_mask;
 263         dmu_buf_impl_t **hash_table;
 264         kmutex_t hash_mutexes[DBUF_MUTEXES];
 265 } dbuf_hash_table_t;
 266
 267 uint64_t dbuf_whichblock(struct dnode *di, int64_t level, uint64_t offset);
 268
 269 dmu_buf_impl_t *dbuf_create_tlib(struct dnode *dn, char *data);
 270 void dbuf_create_bonus(struct dnode *dn);
 271 int dbuf_spill_set_blksz(dmu_buf_t *db, uint64_t blksz, dmu_tx_t *tx);
 272 void dbuf_spill_hold(struct dnode *dn, dmu_buf_impl_t **dbp, void *tag);
 273
 274 void dbuf_rm_spill(struct dnode *dn, dmu_tx_t *tx);
 275
 276 dmu_buf_impl_t *dbuf_hold(struct dnode *dn, uint64_t blkid, void *tag);
 277 dmu_buf_impl_t *dbuf_hold_level(struct dnode *dn, int level, uint64_t blkid,
 278     void *tag);
 279 int dbuf_hold_impl(struct dnode *dn, uint8_t level, uint64_t blkid,
 280     boolean_t fail_sparse, boolean_t fail_uncached,
 281     void *tag, dmu_buf_impl_t **dbp);
 282
 283 void dbuf_prefetch(struct dnode *dn, int64_t level, uint64_t blkid,
 284     zio_priority_t prio, arc_flags_t aflags);
 285
 286 void dbuf_add_ref(dmu_buf_impl_t *db, void *tag);
 287 boolean_t dbuf_try_add_ref(dmu_buf_t *db, objset_t *os, uint64_t obj,
 288     uint64_t blkid, void *tag);
 289 uint64_t dbuf_refcount(dmu_buf_impl_t *db);
 290
 291 void dbuf_rele(dmu_buf_impl_t *db, void *tag);
 292 void dbuf_rele_and_unlock(dmu_buf_impl_t *db, void *tag);
 293
 294 dmu_buf_impl_t *dbuf_find(struct objset *os, uint64_t object, uint8_t level,
 295     uint64_t blkid);
 296
 297 int dbuf_read(dmu_buf_impl_t *db, zio_t *zio, uint32_t flags);
 298 void dmu_buf_will_not_fill(dmu_buf_t *db, dmu_tx_t *tx);
 299 void dmu_buf_will_fill(dmu_buf_t *db, dmu_tx_t *tx);
 300 void dmu_buf_fill_done(dmu_buf_t *db, dmu_tx_t *tx);
 301 void dbuf_assign_arcbuf(dmu_buf_impl_t *db, arc_buf_t *buf, dmu_tx_t *tx);
 302 dbuf_dirty_record_t *dbuf_dirty(dmu_buf_impl_t *db, dmu_tx_t *tx);
 303 arc_buf_t *dbuf_loan_arcbuf(dmu_buf_impl_t *db);
 304 void dmu_buf_write_embedded(dmu_buf_t *dbuf, void *data,
 305     bp_embedded_type_t etype, enum zio_compress comp,
 306     int uncompressed_size, int compressed_size, int byteorder, dmu_tx_t *tx);
 307
 308 void dbuf_clear(dmu_buf_impl_t *db);
 309 void dbuf_evict(dmu_buf_impl_t *db);
 310
 311 void dbuf_setdirty(dmu_buf_impl_t *db, dmu_tx_t *tx);
 312 void dbuf_unoverride(dbuf_dirty_record_t *dr);
 313 void dbuf_sync_list(list_t *list, int level, dmu_tx_t *tx);
 314 void dbuf_release_bp(dmu_buf_impl_t *db);
 315
 316 void dbuf_free_range(struct dnode *dn, uint64_t start, uint64_t end,
 317     struct dmu_tx *);
 318
 319 void dbuf_new_size(dmu_buf_impl_t *db, int size, dmu_tx_t *tx);
 320
 321 #define DB_DNODE(_db)           ((_db)->db_dnode_handle->dnh_dnode)
 322 #define DB_DNODE_LOCK(_db)      ((_db)->db_dnode_handle->dnh_zrlock)
 323 #define DB_DNODE_ENTER(_db)     (zrl_add(&DB_DNODE_LOCK(_db)))
 324 #define DB_DNODE_EXIT(_db)      (zrl_remove(&DB_DNODE_LOCK(_db)))
 325 #define DB_DNODE_HELD(_db)      (!zrl_is_zero(&DB_DNODE_LOCK(_db)))
 326
 327 void dbuf_init(void);
 328 void dbuf_fini(void);
 329
 330 boolean_t dbuf_is_metadata(dmu_buf_impl_t *db);
 331
 332 #define DBUF_GET_BUFC_TYPE(_db) \
 333         (dbuf_is_metadata(_db) ? ARC_BUFC_METADATA : ARC_BUFC_DATA)
 334
 335 #define DBUF_IS_CACHEABLE(_db)                                          \
 336         ((_db)->db_objset->os_primary_cache == ZFS_CACHE_ALL ||         \
 337         (dbuf_is_metadata(_db) &&                                       \
 338         ((_db)->db_objset->os_primary_cache == ZFS_CACHE_METADATA)))
 339
 340 #define DBUF_IS_L2CACHEABLE(_db)                                        \
 341         ((_db)->db_objset->os_secondary_cache == ZFS_CACHE_ALL ||       \
 342         (dbuf_is_metadata(_db) &&                                       \
 343         ((_db)->db_objset->os_secondary_cache == ZFS_CACHE_METADATA)))
 344
 345 #define DBUF_IS_L2COMPRESSIBLE(_db)                                     \
 346         ((_db)->db_objset->os_compress != ZIO_COMPRESS_OFF ||           \
 347         (dbuf_is_metadata(_db) && zfs_mdcomp_disable == B_FALSE))
 348
 349 #ifdef ZFS_DEBUG
 350
 351 /*
 352  * There should be a ## between the string literal and fmt, to make it
 353  * clear that we're joining two strings together, but gcc does not
 354  * support that preprocessor token.
 355  */
 356 #define dprintf_dbuf(dbuf, fmt, ...) do { \
 357         if (zfs_flags & ZFS_DEBUG_DPRINTF) { \
 358         char __db_buf[32]; \
 359         uint64_t __db_obj = (dbuf)->db.db_object; \
 360         if (__db_obj == DMU_META_DNODE_OBJECT) \
 361                 (void) strcpy(__db_buf, "mdn"); \
 362         else \
 363                 (void) snprintf(__db_buf, sizeof (__db_buf), "%lld", \
 364                     (u_longlong_t)__db_obj); \
 365         dprintf_ds((dbuf)->db_objset->os_dsl_dataset, \
 366             "obj=%s lvl=%u blkid=%lld " fmt, \
 367             __db_buf, (dbuf)->db_level, \
 368             (u_longlong_t)(dbuf)->db_blkid, __VA_ARGS__); \
 369         } \
 370 _NOTE(CONSTCOND) } while (0)
 371
 372 #define dprintf_dbuf_bp(db, bp, fmt, ...) do {                  \
 373         if (zfs_flags & ZFS_DEBUG_DPRINTF) {                    \
 374         char *__blkbuf = kmem_alloc(BP_SPRINTF_LEN, KM_SLEEP);  \
 375         snprintf_blkptr(__blkbuf, BP_SPRINTF_LEN, bp);          \
 376         dprintf_dbuf(db, fmt " %s\n", __VA_ARGS__, __blkbuf);   \
 377         kmem_free(__blkbuf, BP_SPRINTF_LEN);                    \
 378         }                                                       \
 379 _NOTE(CONSTCOND) } while (0)
 380
 381 #define DBUF_VERIFY(db) dbuf_verify(db)
 382
 383 #else
 384
 385 #define dprintf_dbuf(db, fmt, ...)
 386 #define dprintf_dbuf_bp(db, bp, fmt, ...)
 387 #define DBUF_VERIFY(db)
 388
 389 #endif
 390
 391
 392 #ifdef  __cplusplus
 393 }
 394 #endif
 395
 396 #endif /* _SYS_DBUF_H */