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