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 by Delphix. All rights reserved.
  24  */
  25 
  26 #ifndef _SYS_DBUF_H
  27 #define _SYS_DBUF_H
  28 
  29 #include <sys/dmu.h>
  30 #include <sys/spa.h>
  31 #include <sys/txg.h>
  32 #include <sys/zio.h>
  33 #include <sys/arc.h>
  34 #include <sys/zfs_context.h>
  35 #include <sys/refcount.h>
  36 #include <sys/zrlock.h>
  37 
  38 #ifdef  __cplusplus
  39 extern "C" {
  40 #endif
  41 
  42 #define IN_DMU_SYNC 2
  43 
  44 /*
  45  * define flags for dbuf_read
  46  */
  47 
  48 #define DB_RF_MUST_SUCCEED      (1 << 0)
  49 #define DB_RF_CANFAIL           (1 << 1)
  50 #define DB_RF_HAVESTRUCT        (1 << 2)
  51 #define DB_RF_NOPREFETCH        (1 << 3)
  52 #define DB_RF_NEVERWAIT         (1 << 4)
  53 #define DB_RF_CACHED            (1 << 5)
  54 
  55 /*
  56  * The simplified state transition diagram for dbufs looks like:
  57  *
  58  *              +----> READ ----+
  59  *              |               |
  60  *              |               V
  61  *  (alloc)-->UNCACHED            CACHED-->EVICTING-->(free)
  62  *              |               ^        ^
  63  *              |               |        |
  64  *              +----> FILL ----+     |
  65  *              |                        |
  66  *              |                        |
  67  *              +--------> NOFILL -------+
  68  */
  69 typedef enum dbuf_states {
  70         DB_UNCACHED,
  71         DB_FILL,
  72         DB_NOFILL,
  73         DB_READ,
  74         DB_CACHED,
  75         DB_EVICTING
  76 } dbuf_states_t;
  77 
  78 struct dnode;
  79 struct dmu_tx;
  80 
  81 /*
  82  * level = 0 means the user data
  83  * level = 1 means the single indirect block
  84  * etc.
  85  */
  86 
  87 struct dmu_buf_impl;
  88 
  89 typedef enum override_states {
  90         DR_NOT_OVERRIDDEN,
  91         DR_IN_DMU_SYNC,
  92         DR_OVERRIDDEN
  93 } override_states_t;
  94 
  95 typedef struct dbuf_dirty_record {
  96         /* link on our parents dirty list */
  97         list_node_t dr_dirty_node;
  98 
  99         /* transaction group this data will sync in */
 100         uint64_t dr_txg;
 101 
 102         /* zio of outstanding write IO */
 103         zio_t *dr_zio;
 104 
 105         /* pointer back to our dbuf */
 106         struct dmu_buf_impl *dr_dbuf;
 107 
 108         /* pointer to next dirty record */
 109         struct dbuf_dirty_record *dr_next;
 110 
 111         /* pointer to parent dirty record */
 112         struct dbuf_dirty_record *dr_parent;
 113 
 114         union dirty_types {
 115                 struct dirty_indirect {
 116 
 117                         /* protect access to list */
 118                         kmutex_t dr_mtx;
 119 
 120                         /* Our list of dirty children */
 121                         list_t dr_children;
 122                 } di;
 123                 struct dirty_leaf {
 124 
 125                         /*
 126                          * dr_data is set when we dirty the buffer
 127                          * so that we can retain the pointer even if it
 128                          * gets COW'd in a subsequent transaction group.
 129                          */
 130                         arc_buf_t *dr_data;
 131                         blkptr_t dr_overridden_by;
 132                         override_states_t dr_override_state;
 133                         uint8_t dr_copies;
 134                         boolean_t dr_nopwrite;
 135                 } dl;
 136         } dt;
 137 } dbuf_dirty_record_t;
 138 
 139 typedef struct dmu_buf_impl {
 140         /*
 141          * The following members are immutable, with the exception of
 142          * db.db_data, which is protected by db_mtx.
 143          */
 144 
 145         /* the publicly visible structure */
 146         dmu_buf_t db;
 147 
 148         /* the objset we belong to */
 149         struct objset *db_objset;
 150 
 151         /*
 152          * handle to safely access the dnode we belong to (NULL when evicted)
 153          */
 154         struct dnode_handle *db_dnode_handle;
 155 
 156         /*
 157          * our parent buffer; if the dnode points to us directly,
 158          * db_parent == db_dnode_handle->dnh_dnode->dn_dbuf
 159          * only accessed by sync thread ???
 160          * (NULL when evicted)
 161          * May change from NULL to non-NULL under the protection of db_mtx
 162          * (see dbuf_check_blkptr())
 163          */
 164         struct dmu_buf_impl *db_parent;
 165 
 166         /*
 167          * link for hash table of all dmu_buf_impl_t's
 168          */
 169         struct dmu_buf_impl *db_hash_next;
 170 
 171         /* our block number */
 172         uint64_t db_blkid;
 173 
 174         /*
 175          * Pointer to the blkptr_t which points to us. May be NULL if we
 176          * don't have one yet. (NULL when evicted)
 177          */
 178         blkptr_t *db_blkptr;
 179 
 180         /*
 181          * Our indirection level.  Data buffers have db_level==0.
 182          * Indirect buffers which point to data buffers have
 183          * db_level==1. etc.  Buffers which contain dnodes have
 184          * db_level==0, since the dnodes are stored in a file.
 185          */
 186         uint8_t db_level;
 187 
 188         /* db_mtx protects the members below */
 189         kmutex_t db_mtx;
 190 
 191         /*
 192          * Current state of the buffer
 193          */
 194         dbuf_states_t db_state;
 195 
 196         /*
 197          * Refcount accessed by dmu_buf_{hold,rele}.
 198          * If nonzero, the buffer can't be destroyed.
 199          * Protected by db_mtx.
 200          */
 201         refcount_t db_holds;
 202 
 203         /* buffer holding our data */
 204         arc_buf_t *db_buf;
 205 
 206         kcondvar_t db_changed;
 207         dbuf_dirty_record_t *db_data_pending;
 208 
 209         /* pointer to most recent dirty record for this buffer */
 210         dbuf_dirty_record_t *db_last_dirty;
 211 
 212         /*
 213          * Our link on the owner dnodes's dn_dbufs list.
 214          * Protected by its dn_dbufs_mtx.
 215          */
 216         list_node_t db_link;
 217 
 218         /* Data which is unique to data (leaf) blocks: */
 219 
 220         /* stuff we store for the user (see dmu_buf_set_user) */
 221         void *db_user_ptr;
 222         void **db_user_data_ptr_ptr;
 223         dmu_buf_evict_func_t *db_evict_func;
 224 
 225         uint8_t db_immediate_evict;
 226         uint8_t db_freed_in_flight;
 227 
 228         uint8_t db_dirtycnt;
 229 } dmu_buf_impl_t;
 230 
 231 /* Note: the dbuf hash table is exposed only for the mdb module */
 232 #define DBUF_MUTEXES 256
 233 #define DBUF_HASH_MUTEX(h, idx) (&(h)->hash_mutexes[(idx) & (DBUF_MUTEXES-1)])
 234 typedef struct dbuf_hash_table {
 235         uint64_t hash_table_mask;
 236         dmu_buf_impl_t **hash_table;
 237         kmutex_t hash_mutexes[DBUF_MUTEXES];
 238 } dbuf_hash_table_t;
 239 
 240 
 241 uint64_t dbuf_whichblock(struct dnode *di, uint64_t offset);
 242 
 243 dmu_buf_impl_t *dbuf_create_tlib(struct dnode *dn, char *data);
 244 void dbuf_create_bonus(struct dnode *dn);
 245 int dbuf_spill_set_blksz(dmu_buf_t *db, uint64_t blksz, dmu_tx_t *tx);
 246 void dbuf_spill_hold(struct dnode *dn, dmu_buf_impl_t **dbp, void *tag);
 247 
 248 void dbuf_rm_spill(struct dnode *dn, dmu_tx_t *tx);
 249 
 250 dmu_buf_impl_t *dbuf_hold(struct dnode *dn, uint64_t blkid, void *tag);
 251 dmu_buf_impl_t *dbuf_hold_level(struct dnode *dn, int level, uint64_t blkid,
 252     void *tag);
 253 int dbuf_hold_impl(struct dnode *dn, uint8_t level, uint64_t blkid, int create,
 254     void *tag, dmu_buf_impl_t **dbp);
 255 
 256 void dbuf_prefetch(struct dnode *dn, uint64_t blkid);
 257 
 258 void dbuf_add_ref(dmu_buf_impl_t *db, void *tag);
 259 uint64_t dbuf_refcount(dmu_buf_impl_t *db);
 260 
 261 void dbuf_rele(dmu_buf_impl_t *db, void *tag);
 262 void dbuf_rele_and_unlock(dmu_buf_impl_t *db, void *tag);
 263 
 264 dmu_buf_impl_t *dbuf_find(struct dnode *dn, uint8_t level, uint64_t blkid);
 265 
 266 int dbuf_read(dmu_buf_impl_t *db, zio_t *zio, uint32_t flags);
 267 void dbuf_will_dirty(dmu_buf_impl_t *db, dmu_tx_t *tx);
 268 void dbuf_fill_done(dmu_buf_impl_t *db, dmu_tx_t *tx);
 269 void dmu_buf_will_not_fill(dmu_buf_t *db, dmu_tx_t *tx);
 270 void dmu_buf_will_fill(dmu_buf_t *db, dmu_tx_t *tx);
 271 void dmu_buf_fill_done(dmu_buf_t *db, dmu_tx_t *tx);
 272 void dbuf_assign_arcbuf(dmu_buf_impl_t *db, arc_buf_t *buf, dmu_tx_t *tx);
 273 dbuf_dirty_record_t *dbuf_dirty(dmu_buf_impl_t *db, dmu_tx_t *tx);
 274 arc_buf_t *dbuf_loan_arcbuf(dmu_buf_impl_t *db);
 275 
 276 void dbuf_clear(dmu_buf_impl_t *db);
 277 void dbuf_evict(dmu_buf_impl_t *db);
 278 
 279 void dbuf_setdirty(dmu_buf_impl_t *db, dmu_tx_t *tx);
 280 void dbuf_unoverride(dbuf_dirty_record_t *dr);
 281 void dbuf_sync_list(list_t *list, dmu_tx_t *tx);
 282 void dbuf_release_bp(dmu_buf_impl_t *db);
 283 
 284 void dbuf_free_range(struct dnode *dn, uint64_t start, uint64_t end,
 285     struct dmu_tx *);
 286 
 287 void dbuf_new_size(dmu_buf_impl_t *db, int size, dmu_tx_t *tx);
 288 
 289 #define DB_DNODE(_db)           ((_db)->db_dnode_handle->dnh_dnode)
 290 #define DB_DNODE_LOCK(_db)      ((_db)->db_dnode_handle->dnh_zrlock)
 291 #define DB_DNODE_ENTER(_db)     (zrl_add(&DB_DNODE_LOCK(_db)))
 292 #define DB_DNODE_EXIT(_db)      (zrl_remove(&DB_DNODE_LOCK(_db)))
 293 #define DB_DNODE_HELD(_db)      (!zrl_is_zero(&DB_DNODE_LOCK(_db)))
 294 #define DB_GET_SPA(_spa_p, _db) {               \
 295         dnode_t *__dn;                          \
 296         DB_DNODE_ENTER(_db);                    \
 297         __dn = DB_DNODE(_db);                   \
 298         *(_spa_p) = __dn->dn_objset->os_spa;      \
 299         DB_DNODE_EXIT(_db);                     \
 300 }
 301 #define DB_GET_OBJSET(_os_p, _db) {             \
 302         dnode_t *__dn;                          \
 303         DB_DNODE_ENTER(_db);                    \
 304         __dn = DB_DNODE(_db);                   \
 305         *(_os_p) = __dn->dn_objset;          \
 306         DB_DNODE_EXIT(_db);                     \
 307 }
 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 #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         sprintf_blkptr(__blkbuf, 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 */