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, 2014 by Delphix. All rights reserved.
  24  * Copyright (c) 2013 by Saso Kiselkov. All rights reserved.
  25  */
  26 
  27 #ifndef _SYS_DBUF_H
  28 #define _SYS_DBUF_H
  29 
  30 #include <sys/dmu.h>
  31 #include <sys/spa.h>
  32 #include <sys/txg.h>
  33 #include <sys/zio.h>
  34 #include <sys/arc.h>
  35 #include <sys/zfs_context.h>
  36 #include <sys/refcount.h>
  37 #include <sys/zrlock.h>
  38 
  39 #ifdef  __cplusplus
  40 extern "C" {
  41 #endif
  42 
  43 #define IN_DMU_SYNC 2
  44 
  45 /*
  46  * define flags for dbuf_read
  47  */
  48 
  49 #define DB_RF_MUST_SUCCEED      (1 << 0)
  50 #define DB_RF_CANFAIL           (1 << 1)
  51 #define DB_RF_HAVESTRUCT        (1 << 2)
  52 #define DB_RF_NOPREFETCH        (1 << 3)
  53 #define DB_RF_NEVERWAIT         (1 << 4)
  54 #define DB_RF_CACHED            (1 << 5)
  55 
  56 /*
  57  * The simplified state transition diagram for dbufs looks like:
  58  *
  59  *              +----> READ ----+
  60  *              |               |
  61  *              |               V
  62  *  (alloc)-->UNCACHED            CACHED-->EVICTING-->(free)
  63  *              |               ^        ^
  64  *              |               |        |
  65  *              +----> FILL ----+     |
  66  *              |                        |
  67  *              |                        |
  68  *              +--------> NOFILL -------+
  69  *
  70  * DB_SEARCH is an invalid state for a dbuf. It is used by dbuf_free_range
  71  * to find all dbufs in a range of a dnode and must be less than any other
  72  * dbuf_states_t (see comment on dn_dbufs in dnode.h).
  73  */
  74 typedef enum dbuf_states {
  75         DB_SEARCH = -1,
  76         DB_UNCACHED,
  77         DB_FILL,
  78         DB_NOFILL,
  79         DB_READ,
  80         DB_CACHED,
  81         DB_EVICTING
  82 } dbuf_states_t;
  83 
  84 struct dnode;
  85 struct dmu_tx;
  86 
  87 /*
  88  * level = 0 means the user data
  89  * level = 1 means the single indirect block
  90  * etc.
  91  */
  92 
  93 struct dmu_buf_impl;
  94 
  95 typedef enum override_states {
  96         DR_NOT_OVERRIDDEN,
  97         DR_IN_DMU_SYNC,
  98         DR_OVERRIDDEN
  99 } override_states_t;
 100 
 101 typedef struct dbuf_dirty_record {
 102         /* link on our parents dirty list */
 103         list_node_t dr_dirty_node;
 104 
 105         /* transaction group this data will sync in */
 106         uint64_t dr_txg;
 107 
 108         /* zio of outstanding write IO */
 109         zio_t *dr_zio;
 110 
 111         /* pointer back to our dbuf */
 112         struct dmu_buf_impl *dr_dbuf;
 113 
 114         /* pointer to next dirty record */
 115         struct dbuf_dirty_record *dr_next;
 116 
 117         /* pointer to parent dirty record */
 118         struct dbuf_dirty_record *dr_parent;
 119 
 120         /* How much space was changed to dsl_pool_dirty_space() for this? */
 121         unsigned int dr_accounted;
 122 
 123         union dirty_types {
 124                 struct dirty_indirect {
 125 
 126                         /* protect access to list */
 127                         kmutex_t dr_mtx;
 128 
 129                         /* Our list of dirty children */
 130                         list_t dr_children;
 131                 } di;
 132                 struct dirty_leaf {
 133 
 134                         /*
 135                          * dr_data is set when we dirty the buffer
 136                          * so that we can retain the pointer even if it
 137                          * gets COW'd in a subsequent transaction group.
 138                          */
 139                         arc_buf_t *dr_data;
 140                         blkptr_t dr_overridden_by;
 141                         override_states_t dr_override_state;
 142                         uint8_t dr_copies;
 143                         boolean_t dr_nopwrite;
 144                 } dl;
 145         } dt;
 146 
 147         boolean_t dr_zero_write;
 148 } dbuf_dirty_record_t;
 149 
 150 typedef struct dmu_buf_impl {
 151         /*
 152          * The following members are immutable, with the exception of
 153          * db.db_data, which is protected by db_mtx.
 154          */
 155 
 156         /* the publicly visible structure */
 157         dmu_buf_t db;
 158 
 159         /* the objset we belong to */
 160         struct objset *db_objset;
 161 
 162         /*
 163          * handle to safely access the dnode we belong to (NULL when evicted)
 164          */
 165         struct dnode_handle *db_dnode_handle;
 166 
 167         /*
 168          * our parent buffer; if the dnode points to us directly,
 169          * db_parent == db_dnode_handle->dnh_dnode->dn_dbuf
 170          * only accessed by sync thread ???
 171          * (NULL when evicted)
 172          * May change from NULL to non-NULL under the protection of db_mtx
 173          * (see dbuf_check_blkptr())
 174          */
 175         struct dmu_buf_impl *db_parent;
 176 
 177         /*
 178          * link for hash table of all dmu_buf_impl_t's
 179          */
 180         struct dmu_buf_impl *db_hash_next;
 181 
 182         /* our block number */
 183         uint64_t db_blkid;
 184 
 185         /*
 186          * Pointer to the blkptr_t which points to us. May be NULL if we
 187          * don't have one yet. (NULL when evicted)
 188          */
 189         blkptr_t *db_blkptr;
 190 
 191         /*
 192          * Our indirection level.  Data buffers have db_level==0.
 193          * Indirect buffers which point to data buffers have
 194          * db_level==1. etc.  Buffers which contain dnodes have
 195          * db_level==0, since the dnodes are stored in a file.
 196          */
 197         uint8_t db_level;
 198 
 199         /* db_mtx protects the members below */
 200         kmutex_t db_mtx;
 201 
 202         /*
 203          * Current state of the buffer
 204          */
 205         dbuf_states_t db_state;
 206 
 207         /*
 208          * Refcount accessed by dmu_buf_{hold,rele}.
 209          * If nonzero, the buffer can't be destroyed.
 210          * Protected by db_mtx.
 211          */
 212         refcount_t db_holds;
 213 
 214         /* buffer holding our data */
 215         arc_buf_t *db_buf;
 216 
 217         kcondvar_t db_changed;
 218         dbuf_dirty_record_t *db_data_pending;
 219 
 220         /* pointer to most recent dirty record for this buffer */
 221         dbuf_dirty_record_t *db_last_dirty;
 222 
 223         /*
 224          * Our link on the owner dnodes's dn_dbufs list.
 225          * Protected by its dn_dbufs_mtx.
 226          */
 227         avl_node_t db_link;
 228 
 229         /* Data which is unique to data (leaf) blocks: */
 230 
 231         /* stuff we store for the user (see dmu_buf_set_user) */
 232         void *db_user_ptr;
 233         void **db_user_data_ptr_ptr;
 234         dmu_buf_evict_func_t *db_evict_func;
 235 
 236         uint8_t db_immediate_evict;
 237         uint8_t db_freed_in_flight;
 238 
 239         uint8_t db_dirtycnt;
 240 } dmu_buf_impl_t;
 241 
 242 /* Note: the dbuf hash table is exposed only for the mdb module */
 243 #define DBUF_MUTEXES 256
 244 #define DBUF_HASH_MUTEX(h, idx) (&(h)->hash_mutexes[(idx) & (DBUF_MUTEXES-1)])
 245 typedef struct dbuf_hash_table {
 246         uint64_t hash_table_mask;
 247         dmu_buf_impl_t **hash_table;
 248         kmutex_t hash_mutexes[DBUF_MUTEXES];
 249 } dbuf_hash_table_t;
 250 
 251 
 252 uint64_t dbuf_whichblock(struct dnode *di, uint64_t offset);
 253 
 254 dmu_buf_impl_t *dbuf_create_tlib(struct dnode *dn, char *data);
 255 void dbuf_create_bonus(struct dnode *dn);
 256 int dbuf_spill_set_blksz(dmu_buf_t *db, uint64_t blksz, dmu_tx_t *tx);
 257 void dbuf_spill_hold(struct dnode *dn, dmu_buf_impl_t **dbp, void *tag);
 258 
 259 void dbuf_rm_spill(struct dnode *dn, dmu_tx_t *tx);
 260 
 261 dmu_buf_impl_t *dbuf_hold(struct dnode *dn, uint64_t blkid, void *tag);
 262 dmu_buf_impl_t *dbuf_hold_level(struct dnode *dn, int level, uint64_t blkid,
 263     void *tag);
 264 int dbuf_hold_impl(struct dnode *dn, uint8_t level, uint64_t blkid, int create,
 265     void *tag, dmu_buf_impl_t **dbp);
 266 
 267 void dbuf_prefetch(struct dnode *dn, uint64_t blkid, zio_priority_t prio);
 268 
 269 void dbuf_add_ref(dmu_buf_impl_t *db, void *tag);
 270 uint64_t dbuf_refcount(dmu_buf_impl_t *db);
 271 
 272 void dbuf_rele(dmu_buf_impl_t *db, void *tag);
 273 void dbuf_rele_and_unlock(dmu_buf_impl_t *db, void *tag);
 274 
 275 dmu_buf_impl_t *dbuf_find(struct dnode *dn, uint8_t level, uint64_t blkid);
 276 
 277 int dbuf_read(dmu_buf_impl_t *db, zio_t *zio, uint32_t flags);
 278 void dmu_buf_will_not_fill(dmu_buf_t *db, dmu_tx_t *tx);
 279 void dmu_buf_will_fill(dmu_buf_t *db, dmu_tx_t *tx);
 280 void dmu_buf_will_zero_fill(dmu_buf_t *db, dmu_tx_t *tx);
 281 void dmu_buf_fill_done(dmu_buf_t *db, dmu_tx_t *tx);
 282 void dbuf_assign_arcbuf(dmu_buf_impl_t *db, arc_buf_t *buf, dmu_tx_t *tx);
 283 dbuf_dirty_record_t *dbuf_dirty(dmu_buf_impl_t *db, dmu_tx_t *tx, boolean_t zero_write);
 284 dbuf_dirty_record_t *dbuf_zero_dirty(dmu_buf_impl_t *db, dmu_tx_t *tx);
 285 arc_buf_t *dbuf_loan_arcbuf(dmu_buf_impl_t *db);
 286 void dmu_buf_write_embedded(dmu_buf_t *dbuf, void *data,
 287     bp_embedded_type_t etype, enum zio_compress comp,
 288     int uncompressed_size, int compressed_size, int byteorder, dmu_tx_t *tx);
 289 
 290 void dbuf_clear(dmu_buf_impl_t *db);
 291 void dbuf_evict(dmu_buf_impl_t *db);
 292 
 293 void dbuf_setdirty(dmu_buf_impl_t *db, dmu_tx_t *tx);
 294 void dbuf_unoverride(dbuf_dirty_record_t *dr);
 295 void dbuf_sync_list(list_t *list, dmu_tx_t *tx);
 296 void dbuf_release_bp(dmu_buf_impl_t *db);
 297 
 298 void dbuf_free_range(struct dnode *dn, uint64_t start, uint64_t end,
 299     struct dmu_tx *);
 300 
 301 void dbuf_new_size(dmu_buf_impl_t *db, int size, dmu_tx_t *tx);
 302 
 303 #define DB_DNODE(_db)           ((_db)->db_dnode_handle->dnh_dnode)
 304 #define DB_DNODE_LOCK(_db)      ((_db)->db_dnode_handle->dnh_zrlock)
 305 #define DB_DNODE_ENTER(_db)     (zrl_add(&DB_DNODE_LOCK(_db)))
 306 #define DB_DNODE_EXIT(_db)      (zrl_remove(&DB_DNODE_LOCK(_db)))
 307 #define DB_DNODE_HELD(_db)      (!zrl_is_zero(&DB_DNODE_LOCK(_db)))
 308 
 309 void dbuf_init(void);
 310 void dbuf_fini(void);
 311 
 312 boolean_t dbuf_is_metadata(dmu_buf_impl_t *db);
 313 
 314 #define DBUF_GET_BUFC_TYPE(_db) \
 315         (dbuf_is_metadata(_db) ? ARC_BUFC_METADATA : ARC_BUFC_DATA)
 316 
 317 #define DBUF_IS_CACHEABLE(_db)                                          \
 318         ((_db)->db_objset->os_primary_cache == ZFS_CACHE_ALL ||           \
 319         (dbuf_is_metadata(_db) &&                                       \
 320         ((_db)->db_objset->os_primary_cache == ZFS_CACHE_METADATA)))
 321 
 322 #define DBUF_IS_L2CACHEABLE(_db)                                        \
 323         ((_db)->db_objset->os_secondary_cache == ZFS_CACHE_ALL || \
 324         (dbuf_is_metadata(_db) &&                                       \
 325         ((_db)->db_objset->os_secondary_cache == ZFS_CACHE_METADATA)))
 326 
 327 #define DBUF_IS_L2COMPRESSIBLE(_db)                                     \
 328         ((_db)->db_objset->os_compress != ZIO_COMPRESS_OFF ||             \
 329         (dbuf_is_metadata(_db) && zfs_mdcomp_disable == B_FALSE))
 330 
 331 #ifdef ZFS_DEBUG
 332 
 333 /*
 334  * There should be a ## between the string literal and fmt, to make it
 335  * clear that we're joining two strings together, but gcc does not
 336  * support that preprocessor token.
 337  */
 338 #define dprintf_dbuf(dbuf, fmt, ...) do { \
 339         if (zfs_flags & ZFS_DEBUG_DPRINTF) { \
 340         char __db_buf[32]; \
 341         uint64_t __db_obj = (dbuf)->db.db_object; \
 342         if (__db_obj == DMU_META_DNODE_OBJECT) \
 343                 (void) strcpy(__db_buf, "mdn"); \
 344         else \
 345                 (void) snprintf(__db_buf, sizeof (__db_buf), "%lld", \
 346                     (u_longlong_t)__db_obj); \
 347         dprintf_ds((dbuf)->db_objset->os_dsl_dataset, \
 348             "obj=%s lvl=%u blkid=%lld " fmt, \
 349             __db_buf, (dbuf)->db_level, \
 350             (u_longlong_t)(dbuf)->db_blkid, __VA_ARGS__); \
 351         } \
 352 _NOTE(CONSTCOND) } while (0)
 353 
 354 #define dprintf_dbuf_bp(db, bp, fmt, ...) do {                  \
 355         if (zfs_flags & ZFS_DEBUG_DPRINTF) {                        \
 356         char *__blkbuf = kmem_alloc(BP_SPRINTF_LEN, KM_SLEEP);  \
 357         snprintf_blkptr(__blkbuf, BP_SPRINTF_LEN, bp);          \
 358         dprintf_dbuf(db, fmt " %s\n", __VA_ARGS__, __blkbuf);   \
 359         kmem_free(__blkbuf, BP_SPRINTF_LEN);                    \
 360         }                                                       \
 361 _NOTE(CONSTCOND) } while (0)
 362 
 363 #define DBUF_VERIFY(db) dbuf_verify(db)
 364 
 365 #else
 366 
 367 #define dprintf_dbuf(db, fmt, ...)
 368 #define dprintf_dbuf_bp(db, bp, fmt, ...)
 369 #define DBUF_VERIFY(db)
 370 
 371 #endif
 372 
 373 
 374 #ifdef  __cplusplus
 375 }
 376 #endif
 377 
 378 #endif /* _SYS_DBUF_H */