FreeBSD/Linux Kernel Cross Reference
sys/contrib/openzfs/include/sys/dbuf.h

     /*
      * CDDL HEADER START
      *
      * The contents of this file are subject to the terms of the
      * Common Development and Distribution License (the "License").
      * You may not use this file except in compliance with the License.
      *
      * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
      * or https://opensource.org/licenses/CDDL-1.0.
     * See the License for the specific language governing permissions
     * and limitations under the License.
     *
     * When distributing Covered Code, include this CDDL HEADER in each
     * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
     * If applicable, add the following below this CDDL HEADER, with the
     * fields enclosed by brackets "[]" replaced with your own identifying
     * information: Portions Copyright [yyyy] [name of copyright owner]
     *
     * CDDL HEADER END
     */
    /*
     * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
     * Copyright (c) 2012, 2020 by Delphix. All rights reserved.
     * Copyright (c) 2013 by Saso Kiselkov. All rights reserved.
     * Copyright (c) 2014 Spectra Logic Corporation, All rights reserved.
     */
    
    #ifndef _SYS_DBUF_H
    #define _SYS_DBUF_H
    
    #include <sys/dmu.h>
    #include <sys/spa.h>
    #include <sys/txg.h>
    #include <sys/zio.h>
    #include <sys/arc.h>
    #include <sys/zfs_context.h>
    #include <sys/zfs_refcount.h>
    #include <sys/zrlock.h>
    #include <sys/multilist.h>
    
    #ifdef  __cplusplus
    extern "C" {
    #endif
    
    #define IN_DMU_SYNC 2
    
    /*
     * define flags for dbuf_read
     */
    
    #define DB_RF_MUST_SUCCEED      (1 << 0)
    #define DB_RF_CANFAIL           (1 << 1)
    #define DB_RF_HAVESTRUCT        (1 << 2)
    #define DB_RF_NOPREFETCH        (1 << 3)
    #define DB_RF_NEVERWAIT         (1 << 4)
    #define DB_RF_CACHED            (1 << 5)
    #define DB_RF_NO_DECRYPT        (1 << 6)
    #define DB_RF_PARTIAL_FIRST     (1 << 7)
    #define DB_RF_PARTIAL_MORE      (1 << 8)
    
    /*
     * The simplified state transition diagram for dbufs looks like:
     *
     *              +----> READ ----+
     *              |               |
     *              |               V
     *  (alloc)-->UNCACHED       CACHED-->EVICTING-->(free)
     *              |               ^        ^
     *              |               |        |
     *              +----> FILL ----+        |
     *              |                        |
     *              |                        |
     *              +--------> NOFILL -------+
     *
     * DB_SEARCH is an invalid state for a dbuf. It is used by dbuf_free_range
     * to find all dbufs in a range of a dnode and must be less than any other
     * dbuf_states_t (see comment on dn_dbufs in dnode.h).
     */
    typedef enum dbuf_states {
            DB_SEARCH = -1,
            DB_UNCACHED,
            DB_FILL,
            DB_NOFILL,
            DB_READ,
            DB_CACHED,
            DB_EVICTING
    } dbuf_states_t;
    
    typedef enum dbuf_cached_state {
            DB_NO_CACHE = -1,
            DB_DBUF_CACHE,
            DB_DBUF_METADATA_CACHE,
            DB_CACHE_MAX
    } dbuf_cached_state_t;
    
    struct dnode;
    struct dmu_tx;
    
    /*
    * level = 0 means the user data
    * level = 1 means the single indirect block
    * etc.
    */
   
   struct dmu_buf_impl;
   
   typedef enum override_states {
           DR_NOT_OVERRIDDEN,
           DR_IN_DMU_SYNC,
           DR_OVERRIDDEN
   } override_states_t;
   
   typedef enum db_lock_type {
           DLT_NONE,
           DLT_PARENT,
           DLT_OBJSET
   } db_lock_type_t;
   
   typedef struct dbuf_dirty_record {
           /* link on our parents dirty list */
           list_node_t dr_dirty_node;
   
           /* transaction group this data will sync in */
           uint64_t dr_txg;
   
           /* zio of outstanding write IO */
           zio_t *dr_zio;
   
           /* pointer back to our dbuf */
           struct dmu_buf_impl *dr_dbuf;
   
           /* list link for dbuf dirty records */
           list_node_t dr_dbuf_node;
   
           /*
            * The dnode we are part of.  Note that the dnode can not be moved or
            * evicted due to the hold that's added by dnode_setdirty() or
            * dmu_objset_sync_dnodes(), and released by dnode_rele_task() or
            * userquota_updates_task().  This hold is necessary for
            * dirty_lightweight_leaf-type dirty records, which don't have a hold
            * on a dbuf.
            */
           dnode_t *dr_dnode;
   
           /* pointer to parent dirty record */
           struct dbuf_dirty_record *dr_parent;
   
           /* How much space was changed to dsl_pool_dirty_space() for this? */
           unsigned int dr_accounted;
   
           /* A copy of the bp that points to us */
           blkptr_t dr_bp_copy;
   
           union dirty_types {
                   struct dirty_indirect {
   
                           /* protect access to list */
                           kmutex_t dr_mtx;
   
                           /* Our list of dirty children */
                           list_t dr_children;
                   } di;
                   struct dirty_leaf {
   
                           /*
                            * dr_data is set when we dirty the buffer
                            * so that we can retain the pointer even if it
                            * gets COW'd in a subsequent transaction group.
                            */
                           arc_buf_t *dr_data;
                           blkptr_t dr_overridden_by;
                           override_states_t dr_override_state;
                           uint8_t dr_copies;
                           boolean_t dr_nopwrite;
                           boolean_t dr_has_raw_params;
   
                           /*
                            * If dr_has_raw_params is set, the following crypt
                            * params will be set on the BP that's written.
                            */
                           boolean_t dr_byteorder;
                           uint8_t dr_salt[ZIO_DATA_SALT_LEN];
                           uint8_t dr_iv[ZIO_DATA_IV_LEN];
                           uint8_t dr_mac[ZIO_DATA_MAC_LEN];
                   } dl;
                   struct dirty_lightweight_leaf {
                           /*
                            * This dirty record refers to a leaf (level=0)
                            * block, whose dbuf has not been instantiated for
                            * performance reasons.
                            */
                           uint64_t dr_blkid;
                           abd_t *dr_abd;
                           zio_prop_t dr_props;
                           zio_flag_t dr_flags;
                   } dll;
           } dt;
   } dbuf_dirty_record_t;
   
   typedef struct dmu_buf_impl {
           /*
            * The following members are immutable, with the exception of
            * db.db_data, which is protected by db_mtx.
            */
   
           /* the publicly visible structure */
           dmu_buf_t db;
   
           /* the objset we belong to */
           struct objset *db_objset;
   
           /*
            * handle to safely access the dnode we belong to (NULL when evicted)
            */
           struct dnode_handle *db_dnode_handle;
   
           /*
            * our parent buffer; if the dnode points to us directly,
            * db_parent == db_dnode_handle->dnh_dnode->dn_dbuf
            * only accessed by sync thread ???
            * (NULL when evicted)
            * May change from NULL to non-NULL under the protection of db_mtx
            * (see dbuf_check_blkptr())
            */
           struct dmu_buf_impl *db_parent;
   
           /*
            * link for hash table of all dmu_buf_impl_t's
            */
           struct dmu_buf_impl *db_hash_next;
   
           /*
            * Our link on the owner dnodes's dn_dbufs list.
            * Protected by its dn_dbufs_mtx.  Should be on the same cache line
            * as db_level and db_blkid for the best avl_add() performance.
            */
           avl_node_t db_link;
   
           /* our block number */
           uint64_t db_blkid;
   
           /*
            * Pointer to the blkptr_t which points to us. May be NULL if we
            * don't have one yet. (NULL when evicted)
            */
           blkptr_t *db_blkptr;
   
           /*
            * Our indirection level.  Data buffers have db_level==0.
            * Indirect buffers which point to data buffers have
            * db_level==1. etc.  Buffers which contain dnodes have
            * db_level==0, since the dnodes are stored in a file.
            */
           uint8_t db_level;
   
           /*
            * Protects db_buf's contents if they contain an indirect block or data
            * block of the meta-dnode. We use this lock to protect the structure of
            * the block tree. This means that when modifying this dbuf's data, we
            * grab its rwlock. When modifying its parent's data (including the
            * blkptr to this dbuf), we grab the parent's rwlock. The lock ordering
            * for this lock is:
            * 1) dn_struct_rwlock
            * 2) db_rwlock
            * We don't currently grab multiple dbufs' db_rwlocks at once.
            */
           krwlock_t db_rwlock;
   
           /* buffer holding our data */
           arc_buf_t *db_buf;
   
           /* db_mtx protects the members below */
           kmutex_t db_mtx;
   
           /*
            * Current state of the buffer
            */
           dbuf_states_t db_state;
   
           /*
            * Refcount accessed by dmu_buf_{hold,rele}.
            * If nonzero, the buffer can't be destroyed.
            * Protected by db_mtx.
            */
           zfs_refcount_t db_holds;
   
           kcondvar_t db_changed;
           dbuf_dirty_record_t *db_data_pending;
   
           /* List of dirty records for the buffer sorted newest to oldest. */
           list_t db_dirty_records;
   
           /* Link in dbuf_cache or dbuf_metadata_cache */
           multilist_node_t db_cache_link;
   
           /* Tells us which dbuf cache this dbuf is in, if any */
           dbuf_cached_state_t db_caching_status;
   
           uint64_t db_hash;
   
           /* Data which is unique to data (leaf) blocks: */
   
           /* User callback information. */
           dmu_buf_user_t *db_user;
   
           /*
            * Evict user data as soon as the dirty and reference
            * counts are equal.
            */
           uint8_t db_user_immediate_evict;
   
           /*
            * This block was freed while a read or write was
            * active.
            */
           uint8_t db_freed_in_flight;
   
           /*
            * dnode_evict_dbufs() or dnode_evict_bonus() tried to
            * evict this dbuf, but couldn't due to outstanding
            * references.  Evict once the refcount drops to 0.
            */
           uint8_t db_pending_evict;
   
           uint8_t db_dirtycnt;
   
           /* The buffer was partially read.  More reads may follow. */
           uint8_t db_partial_read;
   } dmu_buf_impl_t;
   
   #define DBUF_HASH_MUTEX(h, idx) \
           (&(h)->hash_mutexes[(idx) & ((h)->hash_mutex_mask)])
   
   typedef struct dbuf_hash_table {
           uint64_t hash_table_mask;
           uint64_t hash_mutex_mask;
           dmu_buf_impl_t **hash_table;
           kmutex_t *hash_mutexes;
   } dbuf_hash_table_t;
   
   typedef void (*dbuf_prefetch_fn)(void *, uint64_t, uint64_t, boolean_t);
   
   uint64_t dbuf_whichblock(const struct dnode *di, const int64_t level,
       const uint64_t offset);
   
   void dbuf_create_bonus(struct dnode *dn);
   int dbuf_spill_set_blksz(dmu_buf_t *db, uint64_t blksz, dmu_tx_t *tx);
   
   void dbuf_rm_spill(struct dnode *dn, dmu_tx_t *tx);
   
   dmu_buf_impl_t *dbuf_hold(struct dnode *dn, uint64_t blkid, const void *tag);
   dmu_buf_impl_t *dbuf_hold_level(struct dnode *dn, int level, uint64_t blkid,
       const void *tag);
   int dbuf_hold_impl(struct dnode *dn, uint8_t level, uint64_t blkid,
       boolean_t fail_sparse, boolean_t fail_uncached,
       const void *tag, dmu_buf_impl_t **dbp);
   
   int dbuf_prefetch_impl(struct dnode *dn, int64_t level, uint64_t blkid,
       zio_priority_t prio, arc_flags_t aflags, dbuf_prefetch_fn cb,
       void *arg);
   int dbuf_prefetch(struct dnode *dn, int64_t level, uint64_t blkid,
       zio_priority_t prio, arc_flags_t aflags);
   
   void dbuf_add_ref(dmu_buf_impl_t *db, const void *tag);
   boolean_t dbuf_try_add_ref(dmu_buf_t *db, objset_t *os, uint64_t obj,
       uint64_t blkid, const void *tag);
   uint64_t dbuf_refcount(dmu_buf_impl_t *db);
   
   void dbuf_rele(dmu_buf_impl_t *db, const void *tag);
   void dbuf_rele_and_unlock(dmu_buf_impl_t *db, const void *tag,
       boolean_t evicting);
   
   dmu_buf_impl_t *dbuf_find(struct objset *os, uint64_t object, uint8_t level,
       uint64_t blkid, uint64_t *hash_out);
   
   int dbuf_read(dmu_buf_impl_t *db, zio_t *zio, uint32_t flags);
   void dmu_buf_will_not_fill(dmu_buf_t *db, dmu_tx_t *tx);
   void dmu_buf_will_fill(dmu_buf_t *db, dmu_tx_t *tx);
   void dmu_buf_fill_done(dmu_buf_t *db, dmu_tx_t *tx);
   void dbuf_assign_arcbuf(dmu_buf_impl_t *db, arc_buf_t *buf, dmu_tx_t *tx);
   dbuf_dirty_record_t *dbuf_dirty(dmu_buf_impl_t *db, dmu_tx_t *tx);
   dbuf_dirty_record_t *dbuf_dirty_lightweight(dnode_t *dn, uint64_t blkid,
       dmu_tx_t *tx);
   arc_buf_t *dbuf_loan_arcbuf(dmu_buf_impl_t *db);
   void dmu_buf_write_embedded(dmu_buf_t *dbuf, void *data,
       bp_embedded_type_t etype, enum zio_compress comp,
       int uncompressed_size, int compressed_size, int byteorder, dmu_tx_t *tx);
   
   int dmu_lightweight_write_by_dnode(dnode_t *dn, uint64_t offset, abd_t *abd,
       const struct zio_prop *zp, zio_flag_t flags, dmu_tx_t *tx);
   
   void dmu_buf_redact(dmu_buf_t *dbuf, dmu_tx_t *tx);
   void dbuf_destroy(dmu_buf_impl_t *db);
   
   void dbuf_unoverride(dbuf_dirty_record_t *dr);
   void dbuf_sync_list(list_t *list, int level, dmu_tx_t *tx);
   void dbuf_release_bp(dmu_buf_impl_t *db);
   db_lock_type_t dmu_buf_lock_parent(dmu_buf_impl_t *db, krw_t rw,
       const void *tag);
   void dmu_buf_unlock_parent(dmu_buf_impl_t *db, db_lock_type_t type,
       const void *tag);
   
   void dbuf_free_range(struct dnode *dn, uint64_t start, uint64_t end,
       struct dmu_tx *);
   
   void dbuf_new_size(dmu_buf_impl_t *db, int size, dmu_tx_t *tx);
   
   void dbuf_stats_init(dbuf_hash_table_t *hash);
   void dbuf_stats_destroy(void);
   
   int dbuf_dnode_findbp(dnode_t *dn, uint64_t level, uint64_t blkid,
       blkptr_t *bp, uint16_t *datablkszsec, uint8_t *indblkshift);
   
   #define DB_DNODE(_db)           ((_db)->db_dnode_handle->dnh_dnode)
   #define DB_DNODE_LOCK(_db)      ((_db)->db_dnode_handle->dnh_zrlock)
   #define DB_DNODE_ENTER(_db)     (zrl_add(&DB_DNODE_LOCK(_db)))
   #define DB_DNODE_EXIT(_db)      (zrl_remove(&DB_DNODE_LOCK(_db)))
   #define DB_DNODE_HELD(_db)      (!zrl_is_zero(&DB_DNODE_LOCK(_db)))
   
   void dbuf_init(void);
   void dbuf_fini(void);
   
   boolean_t dbuf_is_metadata(dmu_buf_impl_t *db);
   
   static inline dbuf_dirty_record_t *
   dbuf_find_dirty_lte(dmu_buf_impl_t *db, uint64_t txg)
   {
           dbuf_dirty_record_t *dr;
   
           for (dr = list_head(&db->db_dirty_records);
               dr != NULL && dr->dr_txg > txg;
               dr = list_next(&db->db_dirty_records, dr))
                   continue;
           return (dr);
   }
   
   static inline dbuf_dirty_record_t *
   dbuf_find_dirty_eq(dmu_buf_impl_t *db, uint64_t txg)
   {
           dbuf_dirty_record_t *dr;
   
           dr = dbuf_find_dirty_lte(db, txg);
           if (dr && dr->dr_txg == txg)
                   return (dr);
           return (NULL);
   }
   
   #define DBUF_GET_BUFC_TYPE(_db) \
           (dbuf_is_metadata(_db) ? ARC_BUFC_METADATA : ARC_BUFC_DATA)
   
   #define DBUF_IS_CACHEABLE(_db)                                          \
           ((_db)->db_objset->os_primary_cache == ZFS_CACHE_ALL ||         \
           (dbuf_is_metadata(_db) &&                                       \
           ((_db)->db_objset->os_primary_cache == ZFS_CACHE_METADATA)))
   
   boolean_t dbuf_is_l2cacheable(dmu_buf_impl_t *db);
   
   #ifdef ZFS_DEBUG
   
   /*
    * There should be a ## between the string literal and fmt, to make it
    * clear that we're joining two strings together, but gcc does not
    * support that preprocessor token.
    */
   #define dprintf_dbuf(dbuf, fmt, ...) do { \
           if (zfs_flags & ZFS_DEBUG_DPRINTF) { \
           char __db_buf[32]; \
           uint64_t __db_obj = (dbuf)->db.db_object; \
           if (__db_obj == DMU_META_DNODE_OBJECT) \
                   (void) strlcpy(__db_buf, "mdn", sizeof (__db_buf));     \
           else \
                   (void) snprintf(__db_buf, sizeof (__db_buf), "%lld", \
                       (u_longlong_t)__db_obj); \
           dprintf_ds((dbuf)->db_objset->os_dsl_dataset, \
               "obj=%s lvl=%u blkid=%lld " fmt, \
               __db_buf, (dbuf)->db_level, \
               (u_longlong_t)(dbuf)->db_blkid, __VA_ARGS__); \
           } \
   } while (0)
   
   #define dprintf_dbuf_bp(db, bp, fmt, ...) do {                  \
           if (zfs_flags & ZFS_DEBUG_DPRINTF) {                    \
           char *__blkbuf = kmem_alloc(BP_SPRINTF_LEN, KM_SLEEP);  \
           snprintf_blkptr(__blkbuf, BP_SPRINTF_LEN, bp);          \
           dprintf_dbuf(db, fmt " %s\n", __VA_ARGS__, __blkbuf);   \
           kmem_free(__blkbuf, BP_SPRINTF_LEN);                    \
           }                                                       \
   } while (0)
   
   #define DBUF_VERIFY(db) dbuf_verify(db)
   
   #else
   
   #define dprintf_dbuf(db, fmt, ...)
   #define dprintf_dbuf_bp(db, bp, fmt, ...)
   #define DBUF_VERIFY(db)
   
   #endif
   
   
   #ifdef  __cplusplus
   }
   #endif
   
   #endif /* _SYS_DBUF_H */

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