diff options
Diffstat (limited to 'module/zfs/dbuf.c')
| -rw-r--r-- | module/zfs/dbuf.c | 2356 |
1 files changed, 2356 insertions, 0 deletions
diff --git a/module/zfs/dbuf.c b/module/zfs/dbuf.c new file mode 100644 index 000000000..d04610317 --- /dev/null +++ b/module/zfs/dbuf.c @@ -0,0 +1,2356 @@ +/* + * 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 http://www.opensolaris.org/os/licensing. + * 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 2008 Sun Microsystems, Inc. All rights reserved. + * Use is subject to license terms. + */ + +#include <sys/zfs_context.h> +#include <sys/dmu.h> +#include <sys/dmu_impl.h> +#include <sys/dbuf.h> +#include <sys/dmu_objset.h> +#include <sys/dsl_dataset.h> +#include <sys/dsl_dir.h> +#include <sys/dmu_tx.h> +#include <sys/spa.h> +#include <sys/zio.h> +#include <sys/dmu_zfetch.h> + +static void dbuf_destroy(dmu_buf_impl_t *db); +static int dbuf_undirty(dmu_buf_impl_t *db, dmu_tx_t *tx); +static void dbuf_write(dbuf_dirty_record_t *dr, arc_buf_t *data, dmu_tx_t *tx); +static arc_done_func_t dbuf_write_ready; +static arc_done_func_t dbuf_write_done; +static zio_done_func_t dbuf_skip_write_ready; +static zio_done_func_t dbuf_skip_write_done; + +/* + * Global data structures and functions for the dbuf cache. + */ +static kmem_cache_t *dbuf_cache; + +/* ARGSUSED */ +static int +dbuf_cons(void *vdb, void *unused, int kmflag) +{ + dmu_buf_impl_t *db = vdb; + bzero(db, sizeof (dmu_buf_impl_t)); + + mutex_init(&db->db_mtx, NULL, MUTEX_DEFAULT, NULL); + cv_init(&db->db_changed, NULL, CV_DEFAULT, NULL); + refcount_create(&db->db_holds); + return (0); +} + +/* ARGSUSED */ +static void +dbuf_dest(void *vdb, void *unused) +{ + dmu_buf_impl_t *db = vdb; + mutex_destroy(&db->db_mtx); + cv_destroy(&db->db_changed); + refcount_destroy(&db->db_holds); +} + +/* + * dbuf hash table routines + */ +static dbuf_hash_table_t dbuf_hash_table; + +static uint64_t dbuf_hash_count; + +static uint64_t +dbuf_hash(void *os, uint64_t obj, uint8_t lvl, uint64_t blkid) +{ + uintptr_t osv = (uintptr_t)os; + uint64_t crc = -1ULL; + + ASSERT(zfs_crc64_table[128] == ZFS_CRC64_POLY); + crc = (crc >> 8) ^ zfs_crc64_table[(crc ^ (lvl)) & 0xFF]; + crc = (crc >> 8) ^ zfs_crc64_table[(crc ^ (osv >> 6)) & 0xFF]; + crc = (crc >> 8) ^ zfs_crc64_table[(crc ^ (obj >> 0)) & 0xFF]; + crc = (crc >> 8) ^ zfs_crc64_table[(crc ^ (obj >> 8)) & 0xFF]; + crc = (crc >> 8) ^ zfs_crc64_table[(crc ^ (blkid >> 0)) & 0xFF]; + crc = (crc >> 8) ^ zfs_crc64_table[(crc ^ (blkid >> 8)) & 0xFF]; + + crc ^= (osv>>14) ^ (obj>>16) ^ (blkid>>16); + + return (crc); +} + +#define DBUF_HASH(os, obj, level, blkid) dbuf_hash(os, obj, level, blkid); + +#define DBUF_EQUAL(dbuf, os, obj, level, blkid) \ + ((dbuf)->db.db_object == (obj) && \ + (dbuf)->db_objset == (os) && \ + (dbuf)->db_level == (level) && \ + (dbuf)->db_blkid == (blkid)) + +dmu_buf_impl_t * +dbuf_find(dnode_t *dn, uint8_t level, uint64_t blkid) +{ + dbuf_hash_table_t *h = &dbuf_hash_table; + objset_impl_t *os = dn->dn_objset; + uint64_t obj = dn->dn_object; + uint64_t hv = DBUF_HASH(os, obj, level, blkid); + uint64_t idx = hv & h->hash_table_mask; + dmu_buf_impl_t *db; + + mutex_enter(DBUF_HASH_MUTEX(h, idx)); + for (db = h->hash_table[idx]; db != NULL; db = db->db_hash_next) { + if (DBUF_EQUAL(db, os, obj, level, blkid)) { + mutex_enter(&db->db_mtx); + if (db->db_state != DB_EVICTING) { + mutex_exit(DBUF_HASH_MUTEX(h, idx)); + return (db); + } + mutex_exit(&db->db_mtx); + } + } + mutex_exit(DBUF_HASH_MUTEX(h, idx)); + return (NULL); +} + +/* + * Insert an entry into the hash table. If there is already an element + * equal to elem in the hash table, then the already existing element + * will be returned and the new element will not be inserted. + * Otherwise returns NULL. + */ +static dmu_buf_impl_t * +dbuf_hash_insert(dmu_buf_impl_t *db) +{ + dbuf_hash_table_t *h = &dbuf_hash_table; + objset_impl_t *os = db->db_objset; + uint64_t obj = db->db.db_object; + int level = db->db_level; + uint64_t blkid = db->db_blkid; + uint64_t hv = DBUF_HASH(os, obj, level, blkid); + uint64_t idx = hv & h->hash_table_mask; + dmu_buf_impl_t *dbf; + + mutex_enter(DBUF_HASH_MUTEX(h, idx)); + for (dbf = h->hash_table[idx]; dbf != NULL; dbf = dbf->db_hash_next) { + if (DBUF_EQUAL(dbf, os, obj, level, blkid)) { + mutex_enter(&dbf->db_mtx); + if (dbf->db_state != DB_EVICTING) { + mutex_exit(DBUF_HASH_MUTEX(h, idx)); + return (dbf); + } + mutex_exit(&dbf->db_mtx); + } + } + + mutex_enter(&db->db_mtx); + db->db_hash_next = h->hash_table[idx]; + h->hash_table[idx] = db; + mutex_exit(DBUF_HASH_MUTEX(h, idx)); + atomic_add_64(&dbuf_hash_count, 1); + + return (NULL); +} + +/* + * Remove an entry from the hash table. This operation will + * fail if there are any existing holds on the db. + */ +static void +dbuf_hash_remove(dmu_buf_impl_t *db) +{ + dbuf_hash_table_t *h = &dbuf_hash_table; + uint64_t hv = DBUF_HASH(db->db_objset, db->db.db_object, + db->db_level, db->db_blkid); + uint64_t idx = hv & h->hash_table_mask; + dmu_buf_impl_t *dbf, **dbp; + + /* + * We musn't hold db_mtx to maintin lock ordering: + * DBUF_HASH_MUTEX > db_mtx. + */ + ASSERT(refcount_is_zero(&db->db_holds)); + ASSERT(db->db_state == DB_EVICTING); + ASSERT(!MUTEX_HELD(&db->db_mtx)); + + mutex_enter(DBUF_HASH_MUTEX(h, idx)); + dbp = &h->hash_table[idx]; + while ((dbf = *dbp) != db) { + dbp = &dbf->db_hash_next; + ASSERT(dbf != NULL); + } + *dbp = db->db_hash_next; + db->db_hash_next = NULL; + mutex_exit(DBUF_HASH_MUTEX(h, idx)); + atomic_add_64(&dbuf_hash_count, -1); +} + +static arc_evict_func_t dbuf_do_evict; + +static void +dbuf_evict_user(dmu_buf_impl_t *db) +{ + ASSERT(MUTEX_HELD(&db->db_mtx)); + + if (db->db_level != 0 || db->db_evict_func == NULL) + return; + + if (db->db_user_data_ptr_ptr) + *db->db_user_data_ptr_ptr = db->db.db_data; + db->db_evict_func(&db->db, db->db_user_ptr); + db->db_user_ptr = NULL; + db->db_user_data_ptr_ptr = NULL; + db->db_evict_func = NULL; +} + +void +dbuf_evict(dmu_buf_impl_t *db) +{ + ASSERT(MUTEX_HELD(&db->db_mtx)); + ASSERT(db->db_buf == NULL); + ASSERT(db->db_data_pending == NULL); + + dbuf_clear(db); + dbuf_destroy(db); +} + +void +dbuf_init(void) +{ + uint64_t hsize = 1ULL << 16; + dbuf_hash_table_t *h = &dbuf_hash_table; + int i; + + /* + * The hash table is big enough to fill all of physical memory + * with an average 4K block size. The table will take up + * totalmem*sizeof(void*)/4K (i.e. 2MB/GB with 8-byte pointers). + */ + while (hsize * 4096 < physmem * PAGESIZE) + hsize <<= 1; + +retry: + h->hash_table_mask = hsize - 1; + h->hash_table = kmem_zalloc(hsize * sizeof (void *), KM_NOSLEEP); + if (h->hash_table == NULL) { + /* XXX - we should really return an error instead of assert */ + ASSERT(hsize > (1ULL << 10)); + hsize >>= 1; + goto retry; + } + + dbuf_cache = kmem_cache_create("dmu_buf_impl_t", + sizeof (dmu_buf_impl_t), + 0, dbuf_cons, dbuf_dest, NULL, NULL, NULL, 0); + + for (i = 0; i < DBUF_MUTEXES; i++) + mutex_init(&h->hash_mutexes[i], NULL, MUTEX_DEFAULT, NULL); +} + +void +dbuf_fini(void) +{ + dbuf_hash_table_t *h = &dbuf_hash_table; + int i; + + for (i = 0; i < DBUF_MUTEXES; i++) + mutex_destroy(&h->hash_mutexes[i]); + kmem_free(h->hash_table, (h->hash_table_mask + 1) * sizeof (void *)); + kmem_cache_destroy(dbuf_cache); +} + +/* + * Other stuff. + */ + +#ifdef ZFS_DEBUG +static void +dbuf_verify(dmu_buf_impl_t *db) +{ + dnode_t *dn = db->db_dnode; + + ASSERT(MUTEX_HELD(&db->db_mtx)); + + if (!(zfs_flags & ZFS_DEBUG_DBUF_VERIFY)) + return; + + ASSERT(db->db_objset != NULL); + if (dn == NULL) { + ASSERT(db->db_parent == NULL); + ASSERT(db->db_blkptr == NULL); + } else { + ASSERT3U(db->db.db_object, ==, dn->dn_object); + ASSERT3P(db->db_objset, ==, dn->dn_objset); + ASSERT3U(db->db_level, <, dn->dn_nlevels); + ASSERT(db->db_blkid == DB_BONUS_BLKID || + list_head(&dn->dn_dbufs)); + } + if (db->db_blkid == DB_BONUS_BLKID) { + ASSERT(dn != NULL); + ASSERT3U(db->db.db_size, >=, dn->dn_bonuslen); + ASSERT3U(db->db.db_offset, ==, DB_BONUS_BLKID); + } else { + ASSERT3U(db->db.db_offset, ==, db->db_blkid * db->db.db_size); + } + + /* + * We can't assert that db_size matches dn_datablksz because it + * can be momentarily different when another thread is doing + * dnode_set_blksz(). + */ + if (db->db_level == 0 && db->db.db_object == DMU_META_DNODE_OBJECT) { + dbuf_dirty_record_t *dr = db->db_data_pending; + /* + * It should only be modified in syncing context, so + * make sure we only have one copy of the data. + */ + ASSERT(dr == NULL || dr->dt.dl.dr_data == db->db_buf); + } + + /* verify db->db_blkptr */ + if (db->db_blkptr) { + if (db->db_parent == dn->dn_dbuf) { + /* db is pointed to by the dnode */ + /* ASSERT3U(db->db_blkid, <, dn->dn_nblkptr); */ + if (db->db.db_object == DMU_META_DNODE_OBJECT) + ASSERT(db->db_parent == NULL); + else + ASSERT(db->db_parent != NULL); + ASSERT3P(db->db_blkptr, ==, + &dn->dn_phys->dn_blkptr[db->db_blkid]); + } else { + /* db is pointed to by an indirect block */ + int epb = db->db_parent->db.db_size >> SPA_BLKPTRSHIFT; + ASSERT3U(db->db_parent->db_level, ==, db->db_level+1); + ASSERT3U(db->db_parent->db.db_object, ==, + db->db.db_object); + /* + * dnode_grow_indblksz() can make this fail if we don't + * have the struct_rwlock. XXX indblksz no longer + * grows. safe to do this now? + */ + if (RW_WRITE_HELD(&db->db_dnode->dn_struct_rwlock)) { + ASSERT3P(db->db_blkptr, ==, + ((blkptr_t *)db->db_parent->db.db_data + + db->db_blkid % epb)); + } + } + } + if ((db->db_blkptr == NULL || BP_IS_HOLE(db->db_blkptr)) && + db->db.db_data && db->db_blkid != DB_BONUS_BLKID && + db->db_state != DB_FILL && !dn->dn_free_txg) { + /* + * If the blkptr isn't set but they have nonzero data, + * it had better be dirty, otherwise we'll lose that + * data when we evict this buffer. + */ + if (db->db_dirtycnt == 0) { + uint64_t *buf = db->db.db_data; + int i; + + for (i = 0; i < db->db.db_size >> 3; i++) { + ASSERT(buf[i] == 0); + } + } + } +} +#endif + +static void +dbuf_update_data(dmu_buf_impl_t *db) +{ + ASSERT(MUTEX_HELD(&db->db_mtx)); + if (db->db_level == 0 && db->db_user_data_ptr_ptr) { + ASSERT(!refcount_is_zero(&db->db_holds)); + *db->db_user_data_ptr_ptr = db->db.db_data; + } +} + +static void +dbuf_set_data(dmu_buf_impl_t *db, arc_buf_t *buf) +{ + ASSERT(MUTEX_HELD(&db->db_mtx)); + ASSERT(db->db_buf == NULL || !arc_has_callback(db->db_buf)); + db->db_buf = buf; + if (buf != NULL) { + ASSERT(buf->b_data != NULL); + db->db.db_data = buf->b_data; + if (!arc_released(buf)) + arc_set_callback(buf, dbuf_do_evict, db); + dbuf_update_data(db); + } else { + dbuf_evict_user(db); + db->db.db_data = NULL; + if (db->db_state != DB_NOFILL) + db->db_state = DB_UNCACHED; + } +} + +uint64_t +dbuf_whichblock(dnode_t *dn, uint64_t offset) +{ + if (dn->dn_datablkshift) { + return (offset >> dn->dn_datablkshift); + } else { + ASSERT3U(offset, <, dn->dn_datablksz); + return (0); + } +} + +static void +dbuf_read_done(zio_t *zio, arc_buf_t *buf, void *vdb) +{ + dmu_buf_impl_t *db = vdb; + + mutex_enter(&db->db_mtx); + ASSERT3U(db->db_state, ==, DB_READ); + /* + * All reads are synchronous, so we must have a hold on the dbuf + */ + ASSERT(refcount_count(&db->db_holds) > 0); + ASSERT(db->db_buf == NULL); + ASSERT(db->db.db_data == NULL); + if (db->db_level == 0 && db->db_freed_in_flight) { + /* we were freed in flight; disregard any error */ + arc_release(buf, db); + bzero(buf->b_data, db->db.db_size); + arc_buf_freeze(buf); + db->db_freed_in_flight = FALSE; + dbuf_set_data(db, buf); + db->db_state = DB_CACHED; + } else if (zio == NULL || zio->io_error == 0) { + dbuf_set_data(db, buf); + db->db_state = DB_CACHED; + } else { + ASSERT(db->db_blkid != DB_BONUS_BLKID); + ASSERT3P(db->db_buf, ==, NULL); + VERIFY(arc_buf_remove_ref(buf, db) == 1); + db->db_state = DB_UNCACHED; + } + cv_broadcast(&db->db_changed); + mutex_exit(&db->db_mtx); + dbuf_rele(db, NULL); +} + +static void +dbuf_read_impl(dmu_buf_impl_t *db, zio_t *zio, uint32_t *flags) +{ + dnode_t *dn = db->db_dnode; + zbookmark_t zb; + uint32_t aflags = ARC_NOWAIT; + arc_buf_t *pbuf; + + ASSERT(!refcount_is_zero(&db->db_holds)); + /* We need the struct_rwlock to prevent db_blkptr from changing. */ + ASSERT(RW_LOCK_HELD(&dn->dn_struct_rwlock)); + ASSERT(MUTEX_HELD(&db->db_mtx)); + ASSERT(db->db_state == DB_UNCACHED); + ASSERT(db->db_buf == NULL); + + if (db->db_blkid == DB_BONUS_BLKID) { + int bonuslen = dn->dn_bonuslen; + + ASSERT3U(bonuslen, <=, db->db.db_size); + db->db.db_data = zio_buf_alloc(DN_MAX_BONUSLEN); + arc_space_consume(DN_MAX_BONUSLEN); + if (bonuslen < DN_MAX_BONUSLEN) + bzero(db->db.db_data, DN_MAX_BONUSLEN); + bcopy(DN_BONUS(dn->dn_phys), db->db.db_data, + bonuslen); + dbuf_update_data(db); + db->db_state = DB_CACHED; + mutex_exit(&db->db_mtx); + return; + } + + /* + * Recheck BP_IS_HOLE() after dnode_block_freed() in case dnode_sync() + * processes the delete record and clears the bp while we are waiting + * for the dn_mtx (resulting in a "no" from block_freed). + */ + if (db->db_blkptr == NULL || BP_IS_HOLE(db->db_blkptr) || + (db->db_level == 0 && (dnode_block_freed(dn, db->db_blkid) || + BP_IS_HOLE(db->db_blkptr)))) { + arc_buf_contents_t type = DBUF_GET_BUFC_TYPE(db); + + dbuf_set_data(db, arc_buf_alloc(dn->dn_objset->os_spa, + db->db.db_size, db, type)); + bzero(db->db.db_data, db->db.db_size); + db->db_state = DB_CACHED; + *flags |= DB_RF_CACHED; + mutex_exit(&db->db_mtx); + return; + } + + db->db_state = DB_READ; + mutex_exit(&db->db_mtx); + + if (DBUF_IS_L2CACHEABLE(db)) + aflags |= ARC_L2CACHE; + + zb.zb_objset = db->db_objset->os_dsl_dataset ? + db->db_objset->os_dsl_dataset->ds_object : 0; + zb.zb_object = db->db.db_object; + zb.zb_level = db->db_level; + zb.zb_blkid = db->db_blkid; + + dbuf_add_ref(db, NULL); + /* ZIO_FLAG_CANFAIL callers have to check the parent zio's error */ + + if (db->db_parent) + pbuf = db->db_parent->db_buf; + else + pbuf = db->db_objset->os_phys_buf; + + (void) arc_read(zio, dn->dn_objset->os_spa, db->db_blkptr, pbuf, + dbuf_read_done, db, ZIO_PRIORITY_SYNC_READ, + (*flags & DB_RF_CANFAIL) ? ZIO_FLAG_CANFAIL : ZIO_FLAG_MUSTSUCCEED, + &aflags, &zb); + if (aflags & ARC_CACHED) + *flags |= DB_RF_CACHED; +} + +int +dbuf_read(dmu_buf_impl_t *db, zio_t *zio, uint32_t flags) +{ + int err = 0; + int havepzio = (zio != NULL); + int prefetch; + + /* + * We don't have to hold the mutex to check db_state because it + * can't be freed while we have a hold on the buffer. + */ + ASSERT(!refcount_is_zero(&db->db_holds)); + + if (db->db_state == DB_NOFILL) + return (EIO); + + if ((flags & DB_RF_HAVESTRUCT) == 0) + rw_enter(&db->db_dnode->dn_struct_rwlock, RW_READER); + + prefetch = db->db_level == 0 && db->db_blkid != DB_BONUS_BLKID && + (flags & DB_RF_NOPREFETCH) == 0 && db->db_dnode != NULL && + DBUF_IS_CACHEABLE(db); + + mutex_enter(&db->db_mtx); + if (db->db_state == DB_CACHED) { + mutex_exit(&db->db_mtx); + if (prefetch) + dmu_zfetch(&db->db_dnode->dn_zfetch, db->db.db_offset, + db->db.db_size, TRUE); + if ((flags & DB_RF_HAVESTRUCT) == 0) + rw_exit(&db->db_dnode->dn_struct_rwlock); + } else if (db->db_state == DB_UNCACHED) { + if (zio == NULL) { + zio = zio_root(db->db_dnode->dn_objset->os_spa, + NULL, NULL, ZIO_FLAG_CANFAIL); + } + dbuf_read_impl(db, zio, &flags); + + /* dbuf_read_impl has dropped db_mtx for us */ + + if (prefetch) + dmu_zfetch(&db->db_dnode->dn_zfetch, db->db.db_offset, + db->db.db_size, flags & DB_RF_CACHED); + + if ((flags & DB_RF_HAVESTRUCT) == 0) + rw_exit(&db->db_dnode->dn_struct_rwlock); + + if (!havepzio) + err = zio_wait(zio); + } else { + mutex_exit(&db->db_mtx); + if (prefetch) + dmu_zfetch(&db->db_dnode->dn_zfetch, db->db.db_offset, + db->db.db_size, TRUE); + if ((flags & DB_RF_HAVESTRUCT) == 0) + rw_exit(&db->db_dnode->dn_struct_rwlock); + + mutex_enter(&db->db_mtx); + if ((flags & DB_RF_NEVERWAIT) == 0) { + while (db->db_state == DB_READ || + db->db_state == DB_FILL) { + ASSERT(db->db_state == DB_READ || + (flags & DB_RF_HAVESTRUCT) == 0); + cv_wait(&db->db_changed, &db->db_mtx); + } + if (db->db_state == DB_UNCACHED) + err = EIO; + } + mutex_exit(&db->db_mtx); + } + + ASSERT(err || havepzio || db->db_state == DB_CACHED); + return (err); +} + +static void +dbuf_noread(dmu_buf_impl_t *db) +{ + ASSERT(!refcount_is_zero(&db->db_holds)); + ASSERT(db->db_blkid != DB_BONUS_BLKID); + mutex_enter(&db->db_mtx); + while (db->db_state == DB_READ || db->db_state == DB_FILL) + cv_wait(&db->db_changed, &db->db_mtx); + if (db->db_state == DB_UNCACHED) { + arc_buf_contents_t type = DBUF_GET_BUFC_TYPE(db); + + ASSERT(db->db_buf == NULL); + ASSERT(db->db.db_data == NULL); + dbuf_set_data(db, arc_buf_alloc(db->db_dnode->dn_objset->os_spa, + db->db.db_size, db, type)); + db->db_state = DB_FILL; + } else if (db->db_state == DB_NOFILL) { + dbuf_set_data(db, NULL); + } else { + ASSERT3U(db->db_state, ==, DB_CACHED); + } + mutex_exit(&db->db_mtx); +} + +/* + * This is our just-in-time copy function. It makes a copy of + * buffers, that have been modified in a previous transaction + * group, before we modify them in the current active group. + * + * This function is used in two places: when we are dirtying a + * buffer for the first time in a txg, and when we are freeing + * a range in a dnode that includes this buffer. + * + * Note that when we are called from dbuf_free_range() we do + * not put a hold on the buffer, we just traverse the active + * dbuf list for the dnode. + */ +static void +dbuf_fix_old_data(dmu_buf_impl_t *db, uint64_t txg) +{ + dbuf_dirty_record_t *dr = db->db_last_dirty; + + ASSERT(MUTEX_HELD(&db->db_mtx)); + ASSERT(db->db.db_data != NULL); + ASSERT(db->db_level == 0); + ASSERT(db->db.db_object != DMU_META_DNODE_OBJECT); + + if (dr == NULL || + (dr->dt.dl.dr_data != + ((db->db_blkid == DB_BONUS_BLKID) ? db->db.db_data : db->db_buf))) + return; + + /* + * If the last dirty record for this dbuf has not yet synced + * and its referencing the dbuf data, either: + * reset the reference to point to a new copy, + * or (if there a no active holders) + * just null out the current db_data pointer. + */ + ASSERT(dr->dr_txg >= txg - 2); + if (db->db_blkid == DB_BONUS_BLKID) { + /* Note that the data bufs here are zio_bufs */ + dr->dt.dl.dr_data = zio_buf_alloc(DN_MAX_BONUSLEN); + arc_space_consume(DN_MAX_BONUSLEN); + bcopy(db->db.db_data, dr->dt.dl.dr_data, DN_MAX_BONUSLEN); + } else if (refcount_count(&db->db_holds) > db->db_dirtycnt) { + int size = db->db.db_size; + arc_buf_contents_t type = DBUF_GET_BUFC_TYPE(db); + dr->dt.dl.dr_data = arc_buf_alloc( + db->db_dnode->dn_objset->os_spa, size, db, type); + bcopy(db->db.db_data, dr->dt.dl.dr_data->b_data, size); + } else { + dbuf_set_data(db, NULL); + } +} + +void +dbuf_unoverride(dbuf_dirty_record_t *dr) +{ + dmu_buf_impl_t *db = dr->dr_dbuf; + uint64_t txg = dr->dr_txg; + + ASSERT(MUTEX_HELD(&db->db_mtx)); + ASSERT(dr->dt.dl.dr_override_state != DR_IN_DMU_SYNC); + ASSERT(db->db_level == 0); + + if (db->db_blkid == DB_BONUS_BLKID || + dr->dt.dl.dr_override_state == DR_NOT_OVERRIDDEN) + return; + + /* free this block */ + if (!BP_IS_HOLE(&dr->dt.dl.dr_overridden_by)) { + /* XXX can get silent EIO here */ + (void) dsl_free(NULL, + spa_get_dsl(db->db_dnode->dn_objset->os_spa), + txg, &dr->dt.dl.dr_overridden_by, NULL, NULL, ARC_WAIT); + } + dr->dt.dl.dr_override_state = DR_NOT_OVERRIDDEN; + /* + * Release the already-written buffer, so we leave it in + * a consistent dirty state. Note that all callers are + * modifying the buffer, so they will immediately do + * another (redundant) arc_release(). Therefore, leave + * the buf thawed to save the effort of freezing & + * immediately re-thawing it. + */ + arc_release(dr->dt.dl.dr_data, db); +} + +/* + * Evict (if its unreferenced) or clear (if its referenced) any level-0 + * data blocks in the free range, so that any future readers will find + * empty blocks. Also, if we happen accross any level-1 dbufs in the + * range that have not already been marked dirty, mark them dirty so + * they stay in memory. + */ +void +dbuf_free_range(dnode_t *dn, uint64_t start, uint64_t end, dmu_tx_t *tx) +{ + dmu_buf_impl_t *db, *db_next; + uint64_t txg = tx->tx_txg; + int epbs = dn->dn_indblkshift - SPA_BLKPTRSHIFT; + uint64_t first_l1 = start >> epbs; + uint64_t last_l1 = end >> epbs; + + if (end > dn->dn_maxblkid) { + end = dn->dn_maxblkid; + last_l1 = end >> epbs; + } + dprintf_dnode(dn, "start=%llu end=%llu\n", start, end); + mutex_enter(&dn->dn_dbufs_mtx); + for (db = list_head(&dn->dn_dbufs); db; db = db_next) { + db_next = list_next(&dn->dn_dbufs, db); + ASSERT(db->db_blkid != DB_BONUS_BLKID); + + if (db->db_level == 1 && + db->db_blkid >= first_l1 && db->db_blkid <= last_l1) { + mutex_enter(&db->db_mtx); + if (db->db_last_dirty && + db->db_last_dirty->dr_txg < txg) { + dbuf_add_ref(db, FTAG); + mutex_exit(&db->db_mtx); + dbuf_will_dirty(db, tx); + dbuf_rele(db, FTAG); + } else { + mutex_exit(&db->db_mtx); + } + } + + if (db->db_level != 0) + continue; + dprintf_dbuf(db, "found buf %s\n", ""); + if (db->db_blkid < start || db->db_blkid > end) + continue; + + /* found a level 0 buffer in the range */ + if (dbuf_undirty(db, tx)) + continue; + + mutex_enter(&db->db_mtx); + if (db->db_state == DB_UNCACHED || + db->db_state == DB_NOFILL || + db->db_state == DB_EVICTING) { + ASSERT(db->db.db_data == NULL); + mutex_exit(&db->db_mtx); + continue; + } + if (db->db_state == DB_READ || db->db_state == DB_FILL) { + /* will be handled in dbuf_read_done or dbuf_rele */ + db->db_freed_in_flight = TRUE; + mutex_exit(&db->db_mtx); + continue; + } + if (refcount_count(&db->db_holds) == 0) { + ASSERT(db->db_buf); + dbuf_clear(db); + continue; + } + /* The dbuf is referenced */ + + if (db->db_last_dirty != NULL) { + dbuf_dirty_record_t *dr = db->db_last_dirty; + + if (dr->dr_txg == txg) { + /* + * This buffer is "in-use", re-adjust the file + * size to reflect that this buffer may + * contain new data when we sync. + */ + if (db->db_blkid > dn->dn_maxblkid) + dn->dn_maxblkid = db->db_blkid; + dbuf_unoverride(dr); + } else { + /* + * This dbuf is not dirty in the open context. + * Either uncache it (if its not referenced in + * the open context) or reset its contents to + * empty. + */ + dbuf_fix_old_data(db, txg); + } + } + /* clear the contents if its cached */ + if (db->db_state == DB_CACHED) { + ASSERT(db->db.db_data != NULL); + arc_release(db->db_buf, db); + bzero(db->db.db_data, db->db.db_size); + arc_buf_freeze(db->db_buf); + } + + mutex_exit(&db->db_mtx); + } + mutex_exit(&dn->dn_dbufs_mtx); +} + +static int +dbuf_block_freeable(dmu_buf_impl_t *db) +{ + dsl_dataset_t *ds = db->db_objset->os_dsl_dataset; + uint64_t birth_txg = 0; + + /* + * We don't need any locking to protect db_blkptr: + * If it's syncing, then db_last_dirty will be set + * so we'll ignore db_blkptr. + */ + ASSERT(MUTEX_HELD(&db->db_mtx)); + if (db->db_last_dirty) + birth_txg = db->db_last_dirty->dr_txg; + else if (db->db_blkptr) + birth_txg = db->db_blkptr->blk_birth; + + /* If we don't exist or are in a snapshot, we can't be freed */ + if (birth_txg) + return (ds == NULL || + dsl_dataset_block_freeable(ds, birth_txg)); + else + return (FALSE); +} + +void +dbuf_new_size(dmu_buf_impl_t *db, int size, dmu_tx_t *tx) +{ + arc_buf_t *buf, *obuf; + int osize = db->db.db_size; + arc_buf_contents_t type = DBUF_GET_BUFC_TYPE(db); + + ASSERT(db->db_blkid != DB_BONUS_BLKID); + + /* XXX does *this* func really need the lock? */ + ASSERT(RW_WRITE_HELD(&db->db_dnode->dn_struct_rwlock)); + + /* + * This call to dbuf_will_dirty() with the dn_struct_rwlock held + * is OK, because there can be no other references to the db + * when we are changing its size, so no concurrent DB_FILL can + * be happening. + */ + /* + * XXX we should be doing a dbuf_read, checking the return + * value and returning that up to our callers + */ + dbuf_will_dirty(db, tx); + + /* create the data buffer for the new block */ + buf = arc_buf_alloc(db->db_dnode->dn_objset->os_spa, size, db, type); + + /* copy old block data to the new block */ + obuf = db->db_buf; + bcopy(obuf->b_data, buf->b_data, MIN(osize, size)); + /* zero the remainder */ + if (size > osize) + bzero((uint8_t *)buf->b_data + osize, size - osize); + + mutex_enter(&db->db_mtx); + dbuf_set_data(db, buf); + VERIFY(arc_buf_remove_ref(obuf, db) == 1); + db->db.db_size = size; + + if (db->db_level == 0) { + ASSERT3U(db->db_last_dirty->dr_txg, ==, tx->tx_txg); + db->db_last_dirty->dt.dl.dr_data = buf; + } + mutex_exit(&db->db_mtx); + + dnode_willuse_space(db->db_dnode, size-osize, tx); +} + +dbuf_dirty_record_t * +dbuf_dirty(dmu_buf_impl_t *db, dmu_tx_t *tx) +{ + dnode_t *dn = db->db_dnode; + objset_impl_t *os = dn->dn_objset; + dbuf_dirty_record_t **drp, *dr; + int drop_struct_lock = FALSE; + boolean_t do_free_accounting = B_FALSE; + int txgoff = tx->tx_txg & TXG_MASK; + + ASSERT(tx->tx_txg != 0); + ASSERT(!refcount_is_zero(&db->db_holds)); + DMU_TX_DIRTY_BUF(tx, db); + + /* + * Shouldn't dirty a regular buffer in syncing context. Private + * objects may be dirtied in syncing context, but only if they + * were already pre-dirtied in open context. + * XXX We may want to prohibit dirtying in syncing context even + * if they did pre-dirty. + */ + ASSERT(!dmu_tx_is_syncing(tx) || + BP_IS_HOLE(dn->dn_objset->os_rootbp) || + dn->dn_object == DMU_META_DNODE_OBJECT || + dn->dn_objset->os_dsl_dataset == NULL || + dsl_dir_is_private(dn->dn_objset->os_dsl_dataset->ds_dir)); + + /* + * We make this assert for private objects as well, but after we + * check if we're already dirty. They are allowed to re-dirty + * in syncing context. + */ + ASSERT(dn->dn_object == DMU_META_DNODE_OBJECT || + dn->dn_dirtyctx == DN_UNDIRTIED || dn->dn_dirtyctx == + (dmu_tx_is_syncing(tx) ? DN_DIRTY_SYNC : DN_DIRTY_OPEN)); + + mutex_enter(&db->db_mtx); + /* + * XXX make this true for indirects too? The problem is that + * transactions created with dmu_tx_create_assigned() from + * syncing context don't bother holding ahead. + */ + ASSERT(db->db_level != 0 || + db->db_state == DB_CACHED || db->db_state == DB_FILL || + db->db_state == DB_NOFILL); + + mutex_enter(&dn->dn_mtx); + /* + * Don't set dirtyctx to SYNC if we're just modifying this as we + * initialize the objset. + */ + if (dn->dn_dirtyctx == DN_UNDIRTIED && + !BP_IS_HOLE(dn->dn_objset->os_rootbp)) { + dn->dn_dirtyctx = + (dmu_tx_is_syncing(tx) ? DN_DIRTY_SYNC : DN_DIRTY_OPEN); + ASSERT(dn->dn_dirtyctx_firstset == NULL); + dn->dn_dirtyctx_firstset = kmem_alloc(1, KM_SLEEP); + } + mutex_exit(&dn->dn_mtx); + + /* + * If this buffer is already dirty, we're done. + */ + drp = &db->db_last_dirty; + ASSERT(*drp == NULL || (*drp)->dr_txg <= tx->tx_txg || + db->db.db_object == DMU_META_DNODE_OBJECT); + while ((dr = *drp) != NULL && dr->dr_txg > tx->tx_txg) + drp = &dr->dr_next; + if (dr && dr->dr_txg == tx->tx_txg) { + if (db->db_level == 0 && db->db_blkid != DB_BONUS_BLKID) { + /* + * If this buffer has already been written out, + * we now need to reset its state. + */ + dbuf_unoverride(dr); + if (db->db.db_object != DMU_META_DNODE_OBJECT) + arc_buf_thaw(db->db_buf); + } + mutex_exit(&db->db_mtx); + return (dr); + } + + /* + * Only valid if not already dirty. + */ + ASSERT(dn->dn_dirtyctx == DN_UNDIRTIED || dn->dn_dirtyctx == + (dmu_tx_is_syncing(tx) ? DN_DIRTY_SYNC : DN_DIRTY_OPEN)); + + ASSERT3U(dn->dn_nlevels, >, db->db_level); + ASSERT((dn->dn_phys->dn_nlevels == 0 && db->db_level == 0) || + dn->dn_phys->dn_nlevels > db->db_level || + dn->dn_next_nlevels[txgoff] > db->db_level || + dn->dn_next_nlevels[(tx->tx_txg-1) & TXG_MASK] > db->db_level || + dn->dn_next_nlevels[(tx->tx_txg-2) & TXG_MASK] > db->db_level); + + /* + * We should only be dirtying in syncing context if it's the + * mos, a spa os, or we're initializing the os. However, we are + * allowed to dirty in syncing context provided we already + * dirtied it in open context. Hence we must make this + * assertion only if we're not already dirty. + */ + ASSERT(!dmu_tx_is_syncing(tx) || + os->os_dsl_dataset == NULL || + !dsl_dir_is_private(os->os_dsl_dataset->ds_dir) || + !BP_IS_HOLE(os->os_rootbp)); + ASSERT(db->db.db_size != 0); + + dprintf_dbuf(db, "size=%llx\n", (u_longlong_t)db->db.db_size); + + if (db->db_blkid != DB_BONUS_BLKID) { + /* + * Update the accounting. + * Note: we delay "free accounting" until after we drop + * the db_mtx. This keeps us from grabbing other locks + * (and possibly deadlocking) in bp_get_dasize() while + * also holding the db_mtx. + */ + dnode_willuse_space(dn, db->db.db_size, tx); + do_free_accounting = dbuf_block_freeable(db); + } + + /* + * If this buffer is dirty in an old transaction group we need + * to make a copy of it so that the changes we make in this + * transaction group won't leak out when we sync the older txg. + */ + dr = kmem_zalloc(sizeof (dbuf_dirty_record_t), KM_SLEEP); + if (db->db_level == 0) { + void *data_old = db->db_buf; + + if (db->db_state != DB_NOFILL) { + if (db->db_blkid == DB_BONUS_BLKID) { + dbuf_fix_old_data(db, tx->tx_txg); + data_old = db->db.db_data; + } else if (db->db.db_object != DMU_META_DNODE_OBJECT) { + /* + * Release the data buffer from the cache so + * that we can modify it without impacting + * possible other users of this cached data + * block. Note that indirect blocks and + * private objects are not released until the + * syncing state (since they are only modified + * then). + */ + arc_release(db->db_buf, db); + dbuf_fix_old_data(db, tx->tx_txg); + data_old = db->db_buf; + } + ASSERT(data_old != NULL); + } + dr->dt.dl.dr_data = data_old; + } else { + mutex_init(&dr->dt.di.dr_mtx, NULL, MUTEX_DEFAULT, NULL); + list_create(&dr->dt.di.dr_children, + sizeof (dbuf_dirty_record_t), + offsetof(dbuf_dirty_record_t, dr_dirty_node)); + } + dr->dr_dbuf = db; + dr->dr_txg = tx->tx_txg; + dr->dr_next = *drp; + *drp = dr; + + /* + * We could have been freed_in_flight between the dbuf_noread + * and dbuf_dirty. We win, as though the dbuf_noread() had + * happened after the free. + */ + if (db->db_level == 0 && db->db_blkid != DB_BONUS_BLKID) { + mutex_enter(&dn->dn_mtx); + dnode_clear_range(dn, db->db_blkid, 1, tx); + mutex_exit(&dn->dn_mtx); + db->db_freed_in_flight = FALSE; + } + + /* + * This buffer is now part of this txg + */ + dbuf_add_ref(db, (void *)(uintptr_t)tx->tx_txg); + db->db_dirtycnt += 1; + ASSERT3U(db->db_dirtycnt, <=, 3); + + mutex_exit(&db->db_mtx); + + if (db->db_blkid == DB_BONUS_BLKID) { + mutex_enter(&dn->dn_mtx); + ASSERT(!list_link_active(&dr->dr_dirty_node)); + list_insert_tail(&dn->dn_dirty_records[txgoff], dr); + mutex_exit(&dn->dn_mtx); + dnode_setdirty(dn, tx); + return (dr); + } else if (do_free_accounting) { + blkptr_t *bp = db->db_blkptr; + int64_t willfree = (bp && !BP_IS_HOLE(bp)) ? + bp_get_dasize(os->os_spa, bp) : db->db.db_size; + /* + * This is only a guess -- if the dbuf is dirty + * in a previous txg, we don't know how much + * space it will use on disk yet. We should + * really have the struct_rwlock to access + * db_blkptr, but since this is just a guess, + * it's OK if we get an odd answer. + */ + dnode_willuse_space(dn, -willfree, tx); + } + + if (!RW_WRITE_HELD(&dn->dn_struct_rwlock)) { + rw_enter(&dn->dn_struct_rwlock, RW_READER); + drop_struct_lock = TRUE; + } + + if (db->db_level == 0) { + dnode_new_blkid(dn, db->db_blkid, tx, drop_struct_lock); + ASSERT(dn->dn_maxblkid >= db->db_blkid); + } + + if (db->db_level+1 < dn->dn_nlevels) { + dmu_buf_impl_t *parent = db->db_parent; + dbuf_dirty_record_t *di; + int parent_held = FALSE; + + if (db->db_parent == NULL || db->db_parent == dn->dn_dbuf) { + int epbs = dn->dn_indblkshift - SPA_BLKPTRSHIFT; + + parent = dbuf_hold_level(dn, db->db_level+1, + db->db_blkid >> epbs, FTAG); + parent_held = TRUE; + } + if (drop_struct_lock) + rw_exit(&dn->dn_struct_rwlock); + ASSERT3U(db->db_level+1, ==, parent->db_level); + di = dbuf_dirty(parent, tx); + if (parent_held) + dbuf_rele(parent, FTAG); + + mutex_enter(&db->db_mtx); + /* possible race with dbuf_undirty() */ + if (db->db_last_dirty == dr || + dn->dn_object == DMU_META_DNODE_OBJECT) { + mutex_enter(&di->dt.di.dr_mtx); + ASSERT3U(di->dr_txg, ==, tx->tx_txg); + ASSERT(!list_link_active(&dr->dr_dirty_node)); + list_insert_tail(&di->dt.di.dr_children, dr); + mutex_exit(&di->dt.di.dr_mtx); + dr->dr_parent = di; + } + mutex_exit(&db->db_mtx); + } else { + ASSERT(db->db_level+1 == dn->dn_nlevels); + ASSERT(db->db_blkid < dn->dn_nblkptr); + ASSERT(db->db_parent == NULL || + db->db_parent == db->db_dnode->dn_dbuf); + mutex_enter(&dn->dn_mtx); + ASSERT(!list_link_active(&dr->dr_dirty_node)); + list_insert_tail(&dn->dn_dirty_records[txgoff], dr); + mutex_exit(&dn->dn_mtx); + if (drop_struct_lock) + rw_exit(&dn->dn_struct_rwlock); + } + + dnode_setdirty(dn, tx); + return (dr); +} + +static int +dbuf_undirty(dmu_buf_impl_t *db, dmu_tx_t *tx) +{ + dnode_t *dn = db->db_dnode; + uint64_t txg = tx->tx_txg; + dbuf_dirty_record_t *dr, **drp; + + ASSERT(txg != 0); + ASSERT(db->db_blkid != DB_BONUS_BLKID); + + mutex_enter(&db->db_mtx); + + /* + * If this buffer is not dirty, we're done. + */ + for (drp = &db->db_last_dirty; (dr = *drp) != NULL; drp = &dr->dr_next) + if (dr->dr_txg <= txg) + break; + if (dr == NULL || dr->dr_txg < txg) { + mutex_exit(&db->db_mtx); + return (0); + } + ASSERT(dr->dr_txg == txg); + + /* + * If this buffer is currently held, we cannot undirty + * it, since one of the current holders may be in the + * middle of an update. Note that users of dbuf_undirty() + * should not place a hold on the dbuf before the call. + */ + if (refcount_count(&db->db_holds) > db->db_dirtycnt) { + mutex_exit(&db->db_mtx); + /* Make sure we don't toss this buffer at sync phase */ + mutex_enter(&dn->dn_mtx); + dnode_clear_range(dn, db->db_blkid, 1, tx); + mutex_exit(&dn->dn_mtx); + return (0); + } + + dprintf_dbuf(db, "size=%llx\n", (u_longlong_t)db->db.db_size); + + ASSERT(db->db.db_size != 0); + + /* XXX would be nice to fix up dn_towrite_space[] */ + + *drp = dr->dr_next; + + if (dr->dr_parent) { + mutex_enter(&dr->dr_parent->dt.di.dr_mtx); + list_remove(&dr->dr_parent->dt.di.dr_children, dr); + mutex_exit(&dr->dr_parent->dt.di.dr_mtx); + } else if (db->db_level+1 == dn->dn_nlevels) { + ASSERT(db->db_blkptr == NULL || db->db_parent == dn->dn_dbuf); + mutex_enter(&dn->dn_mtx); + list_remove(&dn->dn_dirty_records[txg & TXG_MASK], dr); + mutex_exit(&dn->dn_mtx); + } + + if (db->db_level == 0) { + if (db->db_state != DB_NOFILL) { + dbuf_unoverride(dr); + + ASSERT(db->db_buf != NULL); + ASSERT(dr->dt.dl.dr_data != NULL); + if (dr->dt.dl.dr_data != db->db_buf) + VERIFY(arc_buf_remove_ref(dr->dt.dl.dr_data, + db) == 1); + } + } else { + ASSERT(db->db_buf != NULL); + ASSERT(list_head(&dr->dt.di.dr_children) == NULL); + mutex_destroy(&dr->dt.di.dr_mtx); + list_destroy(&dr->dt.di.dr_children); + } + kmem_free(dr, sizeof (dbuf_dirty_record_t)); + + ASSERT(db->db_dirtycnt > 0); + db->db_dirtycnt -= 1; + + if (refcount_remove(&db->db_holds, (void *)(uintptr_t)txg) == 0) { + arc_buf_t *buf = db->db_buf; + + ASSERT(arc_released(buf)); + dbuf_set_data(db, NULL); + VERIFY(arc_buf_remove_ref(buf, db) == 1); + dbuf_evict(db); + return (1); + } + + mutex_exit(&db->db_mtx); + return (0); +} + +#pragma weak dmu_buf_will_dirty = dbuf_will_dirty +void +dbuf_will_dirty(dmu_buf_impl_t *db, dmu_tx_t *tx) +{ + int rf = DB_RF_MUST_SUCCEED | DB_RF_NOPREFETCH; + + ASSERT(tx->tx_txg != 0); + ASSERT(!refcount_is_zero(&db->db_holds)); + + if (RW_WRITE_HELD(&db->db_dnode->dn_struct_rwlock)) + rf |= DB_RF_HAVESTRUCT; + (void) dbuf_read(db, NULL, rf); + (void) dbuf_dirty(db, tx); +} + +void +dmu_buf_will_not_fill(dmu_buf_t *db_fake, dmu_tx_t *tx) +{ + dmu_buf_impl_t *db = (dmu_buf_impl_t *)db_fake; + + db->db_state = DB_NOFILL; + + dmu_buf_will_fill(db_fake, tx); +} + +void +dmu_buf_will_fill(dmu_buf_t *db_fake, dmu_tx_t *tx) +{ + dmu_buf_impl_t *db = (dmu_buf_impl_t *)db_fake; + + ASSERT(db->db_blkid != DB_BONUS_BLKID); + ASSERT(tx->tx_txg != 0); + ASSERT(db->db_level == 0); + ASSERT(!refcount_is_zero(&db->db_holds)); + + ASSERT(db->db.db_object != DMU_META_DNODE_OBJECT || + dmu_tx_private_ok(tx)); + + dbuf_noread(db); + (void) dbuf_dirty(db, tx); +} + +#pragma weak dmu_buf_fill_done = dbuf_fill_done +/* ARGSUSED */ +void +dbuf_fill_done(dmu_buf_impl_t *db, dmu_tx_t *tx) +{ + mutex_enter(&db->db_mtx); + DBUF_VERIFY(db); + + if (db->db_state == DB_FILL) { + if (db->db_level == 0 && db->db_freed_in_flight) { + ASSERT(db->db_blkid != DB_BONUS_BLKID); + /* we were freed while filling */ + /* XXX dbuf_undirty? */ + bzero(db->db.db_data, db->db.db_size); + db->db_freed_in_flight = FALSE; + } + db->db_state = DB_CACHED; + cv_broadcast(&db->db_changed); + } + mutex_exit(&db->db_mtx); +} + +/* + * "Clear" the contents of this dbuf. This will mark the dbuf + * EVICTING and clear *most* of its references. Unfortunetely, + * when we are not holding the dn_dbufs_mtx, we can't clear the + * entry in the dn_dbufs list. We have to wait until dbuf_destroy() + * in this case. For callers from the DMU we will usually see: + * dbuf_clear()->arc_buf_evict()->dbuf_do_evict()->dbuf_destroy() + * For the arc callback, we will usually see: + * dbuf_do_evict()->dbuf_clear();dbuf_destroy() + * Sometimes, though, we will get a mix of these two: + * DMU: dbuf_clear()->arc_buf_evict() + * ARC: dbuf_do_evict()->dbuf_destroy() + */ +void +dbuf_clear(dmu_buf_impl_t *db) +{ + dnode_t *dn = db->db_dnode; + dmu_buf_impl_t *parent = db->db_parent; + dmu_buf_impl_t *dndb = dn->dn_dbuf; + int dbuf_gone = FALSE; + + ASSERT(MUTEX_HELD(&db->db_mtx)); + ASSERT(refcount_is_zero(&db->db_holds)); + + dbuf_evict_user(db); + + if (db->db_state == DB_CACHED) { + ASSERT(db->db.db_data != NULL); + if (db->db_blkid == DB_BONUS_BLKID) { + zio_buf_free(db->db.db_data, DN_MAX_BONUSLEN); + arc_space_return(DN_MAX_BONUSLEN); + } + db->db.db_data = NULL; + db->db_state = DB_UNCACHED; + } + + ASSERT(db->db_state == DB_UNCACHED || db->db_state == DB_NOFILL); + ASSERT(db->db_data_pending == NULL); + + db->db_state = DB_EVICTING; + db->db_blkptr = NULL; + + if (db->db_blkid != DB_BONUS_BLKID && MUTEX_HELD(&dn->dn_dbufs_mtx)) { + list_remove(&dn->dn_dbufs, db); + dnode_rele(dn, db); + db->db_dnode = NULL; + } + + if (db->db_buf) + dbuf_gone = arc_buf_evict(db->db_buf); + + if (!dbuf_gone) + mutex_exit(&db->db_mtx); + + /* + * If this dbuf is referened from an indirect dbuf, + * decrement the ref count on the indirect dbuf. + */ + if (parent && parent != dndb) + dbuf_rele(parent, db); +} + +static int +dbuf_findbp(dnode_t *dn, int level, uint64_t blkid, int fail_sparse, + dmu_buf_impl_t **parentp, blkptr_t **bpp) +{ + int nlevels, epbs; + + *parentp = NULL; + *bpp = NULL; + + ASSERT(blkid != DB_BONUS_BLKID); + + if (dn->dn_phys->dn_nlevels == 0) + nlevels = 1; + else + nlevels = dn->dn_phys->dn_nlevels; + + epbs = dn->dn_indblkshift - SPA_BLKPTRSHIFT; + + ASSERT3U(level * epbs, <, 64); + ASSERT(RW_LOCK_HELD(&dn->dn_struct_rwlock)); + if (level >= nlevels || + (blkid > (dn->dn_phys->dn_maxblkid >> (level * epbs)))) { + /* the buffer has no parent yet */ + return (ENOENT); + } else if (level < nlevels-1) { + /* this block is referenced from an indirect block */ + int err = dbuf_hold_impl(dn, level+1, + blkid >> epbs, fail_sparse, NULL, parentp); + if (err) + return (err); + err = dbuf_read(*parentp, NULL, + (DB_RF_HAVESTRUCT | DB_RF_NOPREFETCH | DB_RF_CANFAIL)); + if (err) { + dbuf_rele(*parentp, NULL); + *parentp = NULL; + return (err); + } + *bpp = ((blkptr_t *)(*parentp)->db.db_data) + + (blkid & ((1ULL << epbs) - 1)); + return (0); + } else { + /* the block is referenced from the dnode */ + ASSERT3U(level, ==, nlevels-1); + ASSERT(dn->dn_phys->dn_nblkptr == 0 || + blkid < dn->dn_phys->dn_nblkptr); + if (dn->dn_dbuf) { + dbuf_add_ref(dn->dn_dbuf, NULL); + *parentp = dn->dn_dbuf; + } + *bpp = &dn->dn_phys->dn_blkptr[blkid]; + return (0); + } +} + +static dmu_buf_impl_t * +dbuf_create(dnode_t *dn, uint8_t level, uint64_t blkid, + dmu_buf_impl_t *parent, blkptr_t *blkptr) +{ + objset_impl_t *os = dn->dn_objset; + dmu_buf_impl_t *db, *odb; + + ASSERT(RW_LOCK_HELD(&dn->dn_struct_rwlock)); + ASSERT(dn->dn_type != DMU_OT_NONE); + + db = kmem_cache_alloc(dbuf_cache, KM_SLEEP); + + db->db_objset = os; + db->db.db_object = dn->dn_object; + db->db_level = level; + db->db_blkid = blkid; + db->db_last_dirty = NULL; + db->db_dirtycnt = 0; + db->db_dnode = dn; + db->db_parent = parent; + db->db_blkptr = blkptr; + + db->db_user_ptr = NULL; + db->db_user_data_ptr_ptr = NULL; + db->db_evict_func = NULL; + db->db_immediate_evict = 0; + db->db_freed_in_flight = 0; + + if (blkid == DB_BONUS_BLKID) { + ASSERT3P(parent, ==, dn->dn_dbuf); + db->db.db_size = DN_MAX_BONUSLEN - + (dn->dn_nblkptr-1) * sizeof (blkptr_t); + ASSERT3U(db->db.db_size, >=, dn->dn_bonuslen); + db->db.db_offset = DB_BONUS_BLKID; + db->db_state = DB_UNCACHED; + /* the bonus dbuf is not placed in the hash table */ + arc_space_consume(sizeof (dmu_buf_impl_t)); + return (db); + } else { + int blocksize = + db->db_level ? 1<<dn->dn_indblkshift : dn->dn_datablksz; + db->db.db_size = blocksize; + db->db.db_offset = db->db_blkid * blocksize; + } + + /* + * Hold the dn_dbufs_mtx while we get the new dbuf + * in the hash table *and* added to the dbufs list. + * This prevents a possible deadlock with someone + * trying to look up this dbuf before its added to the + * dn_dbufs list. + */ + mutex_enter(&dn->dn_dbufs_mtx); + db->db_state = DB_EVICTING; + if ((odb = dbuf_hash_insert(db)) != NULL) { + /* someone else inserted it first */ + kmem_cache_free(dbuf_cache, db); + mutex_exit(&dn->dn_dbufs_mtx); + return (odb); + } + list_insert_head(&dn->dn_dbufs, db); + db->db_state = DB_UNCACHED; + mutex_exit(&dn->dn_dbufs_mtx); + arc_space_consume(sizeof (dmu_buf_impl_t)); + + if (parent && parent != dn->dn_dbuf) + dbuf_add_ref(parent, db); + + ASSERT(dn->dn_object == DMU_META_DNODE_OBJECT || + refcount_count(&dn->dn_holds) > 0); + (void) refcount_add(&dn->dn_holds, db); + + dprintf_dbuf(db, "db=%p\n", db); + + return (db); +} + +static int +dbuf_do_evict(void *private) +{ + arc_buf_t *buf = private; + dmu_buf_impl_t *db = buf->b_private; + + if (!MUTEX_HELD(&db->db_mtx)) + mutex_enter(&db->db_mtx); + + ASSERT(refcount_is_zero(&db->db_holds)); + + if (db->db_state != DB_EVICTING) { + ASSERT(db->db_state == DB_CACHED); + DBUF_VERIFY(db); + db->db_buf = NULL; + dbuf_evict(db); + } else { + mutex_exit(&db->db_mtx); + dbuf_destroy(db); + } + return (0); +} + +static void +dbuf_destroy(dmu_buf_impl_t *db) +{ + ASSERT(refcount_is_zero(&db->db_holds)); + + if (db->db_blkid != DB_BONUS_BLKID) { + /* + * If this dbuf is still on the dn_dbufs list, + * remove it from that list. + */ + if (db->db_dnode) { + dnode_t *dn = db->db_dnode; + + mutex_enter(&dn->dn_dbufs_mtx); + list_remove(&dn->dn_dbufs, db); + mutex_exit(&dn->dn_dbufs_mtx); + + dnode_rele(dn, db); + db->db_dnode = NULL; + } + dbuf_hash_remove(db); + } + db->db_parent = NULL; + db->db_buf = NULL; + + ASSERT(!list_link_active(&db->db_link)); + ASSERT(db->db.db_data == NULL); + ASSERT(db->db_hash_next == NULL); + ASSERT(db->db_blkptr == NULL); + ASSERT(db->db_data_pending == NULL); + + kmem_cache_free(dbuf_cache, db); + arc_space_return(sizeof (dmu_buf_impl_t)); +} + +void +dbuf_prefetch(dnode_t *dn, uint64_t blkid) +{ + dmu_buf_impl_t *db = NULL; + blkptr_t *bp = NULL; + + ASSERT(blkid != DB_BONUS_BLKID); + ASSERT(RW_LOCK_HELD(&dn->dn_struct_rwlock)); + + if (dnode_block_freed(dn, blkid)) + return; + + /* dbuf_find() returns with db_mtx held */ + if (db = dbuf_find(dn, 0, blkid)) { + if (refcount_count(&db->db_holds) > 0) { + /* + * This dbuf is active. We assume that it is + * already CACHED, or else about to be either + * read or filled. + */ + mutex_exit(&db->db_mtx); + return; + } + mutex_exit(&db->db_mtx); + db = NULL; + } + + if (dbuf_findbp(dn, 0, blkid, TRUE, &db, &bp) == 0) { + if (bp && !BP_IS_HOLE(bp)) { + arc_buf_t *pbuf; + uint32_t aflags = ARC_NOWAIT | ARC_PREFETCH; + zbookmark_t zb; + zb.zb_objset = dn->dn_objset->os_dsl_dataset ? + dn->dn_objset->os_dsl_dataset->ds_object : 0; + zb.zb_object = dn->dn_object; + zb.zb_level = 0; + zb.zb_blkid = blkid; + + if (db) + pbuf = db->db_buf; + else + pbuf = dn->dn_objset->os_phys_buf; + + (void) arc_read(NULL, dn->dn_objset->os_spa, + bp, pbuf, NULL, NULL, ZIO_PRIORITY_ASYNC_READ, + ZIO_FLAG_CANFAIL | ZIO_FLAG_SPECULATIVE, + &aflags, &zb); + } + if (db) + dbuf_rele(db, NULL); + } +} + +/* + * Returns with db_holds incremented, and db_mtx not held. + * Note: dn_struct_rwlock must be held. + */ +int +dbuf_hold_impl(dnode_t *dn, uint8_t level, uint64_t blkid, int fail_sparse, + void *tag, dmu_buf_impl_t **dbp) +{ + dmu_buf_impl_t *db, *parent = NULL; + + ASSERT(blkid != DB_BONUS_BLKID); + ASSERT(RW_LOCK_HELD(&dn->dn_struct_rwlock)); + ASSERT3U(dn->dn_nlevels, >, level); + + *dbp = NULL; +top: + /* dbuf_find() returns with db_mtx held */ + db = dbuf_find(dn, level, blkid); + + if (db == NULL) { + blkptr_t *bp = NULL; + int err; + + ASSERT3P(parent, ==, NULL); + err = dbuf_findbp(dn, level, blkid, fail_sparse, &parent, &bp); + if (fail_sparse) { + if (err == 0 && bp && BP_IS_HOLE(bp)) + err = ENOENT; + if (err) { + if (parent) + dbuf_rele(parent, NULL); + return (err); + } + } + if (err && err != ENOENT) + return (err); + db = dbuf_create(dn, level, blkid, parent, bp); + } + + if (db->db_buf && refcount_is_zero(&db->db_holds)) { + arc_buf_add_ref(db->db_buf, db); + if (db->db_buf->b_data == NULL) { + dbuf_clear(db); + if (parent) { + dbuf_rele(parent, NULL); + parent = NULL; + } + goto top; + } + ASSERT3P(db->db.db_data, ==, db->db_buf->b_data); + } + + ASSERT(db->db_buf == NULL || arc_referenced(db->db_buf)); + + /* + * If this buffer is currently syncing out, and we are are + * still referencing it from db_data, we need to make a copy + * of it in case we decide we want to dirty it again in this txg. + */ + if (db->db_level == 0 && db->db_blkid != DB_BONUS_BLKID && + dn->dn_object != DMU_META_DNODE_OBJECT && + db->db_state == DB_CACHED && db->db_data_pending) { + dbuf_dirty_record_t *dr = db->db_data_pending; + + if (dr->dt.dl.dr_data == db->db_buf) { + arc_buf_contents_t type = DBUF_GET_BUFC_TYPE(db); + + dbuf_set_data(db, + arc_buf_alloc(db->db_dnode->dn_objset->os_spa, + db->db.db_size, db, type)); + bcopy(dr->dt.dl.dr_data->b_data, db->db.db_data, + db->db.db_size); + } + } + + (void) refcount_add(&db->db_holds, tag); + dbuf_update_data(db); + DBUF_VERIFY(db); + mutex_exit(&db->db_mtx); + + /* NOTE: we can't rele the parent until after we drop the db_mtx */ + if (parent) + dbuf_rele(parent, NULL); + + ASSERT3P(db->db_dnode, ==, dn); + ASSERT3U(db->db_blkid, ==, blkid); + ASSERT3U(db->db_level, ==, level); + *dbp = db; + + return (0); +} + +dmu_buf_impl_t * +dbuf_hold(dnode_t *dn, uint64_t blkid, void *tag) +{ + dmu_buf_impl_t *db; + int err = dbuf_hold_impl(dn, 0, blkid, FALSE, tag, &db); + return (err ? NULL : db); +} + +dmu_buf_impl_t * +dbuf_hold_level(dnode_t *dn, int level, uint64_t blkid, void *tag) +{ + dmu_buf_impl_t *db; + int err = dbuf_hold_impl(dn, level, blkid, FALSE, tag, &db); + return (err ? NULL : db); +} + +void +dbuf_create_bonus(dnode_t *dn) +{ + ASSERT(RW_WRITE_HELD(&dn->dn_struct_rwlock)); + + ASSERT(dn->dn_bonus == NULL); + dn->dn_bonus = dbuf_create(dn, 0, DB_BONUS_BLKID, dn->dn_dbuf, NULL); +} + +#pragma weak dmu_buf_add_ref = dbuf_add_ref +void +dbuf_add_ref(dmu_buf_impl_t *db, void *tag) +{ + int64_t holds = refcount_add(&db->db_holds, tag); + ASSERT(holds > 1); +} + +#pragma weak dmu_buf_rele = dbuf_rele +void +dbuf_rele(dmu_buf_impl_t *db, void *tag) +{ + int64_t holds; + + mutex_enter(&db->db_mtx); + DBUF_VERIFY(db); + + holds = refcount_remove(&db->db_holds, tag); + ASSERT(holds >= 0); + + /* + * We can't freeze indirects if there is a possibility that they + * may be modified in the current syncing context. + */ + if (db->db_buf && holds == (db->db_level == 0 ? db->db_dirtycnt : 0)) + arc_buf_freeze(db->db_buf); + + if (holds == db->db_dirtycnt && + db->db_level == 0 && db->db_immediate_evict) + dbuf_evict_user(db); + + if (holds == 0) { + if (db->db_blkid == DB_BONUS_BLKID) { + mutex_exit(&db->db_mtx); + dnode_rele(db->db_dnode, db); + } else if (db->db_buf == NULL) { + /* + * This is a special case: we never associated this + * dbuf with any data allocated from the ARC. + */ + ASSERT(db->db_state == DB_UNCACHED || + db->db_state == DB_NOFILL); + dbuf_evict(db); + } else if (arc_released(db->db_buf)) { + arc_buf_t *buf = db->db_buf; + /* + * This dbuf has anonymous data associated with it. + */ + dbuf_set_data(db, NULL); + VERIFY(arc_buf_remove_ref(buf, db) == 1); + dbuf_evict(db); + } else { + VERIFY(arc_buf_remove_ref(db->db_buf, db) == 0); + if (!DBUF_IS_CACHEABLE(db)) + dbuf_clear(db); + else + mutex_exit(&db->db_mtx); + } + } else { + mutex_exit(&db->db_mtx); + } +} + +#pragma weak dmu_buf_refcount = dbuf_refcount +uint64_t +dbuf_refcount(dmu_buf_impl_t *db) +{ + return (refcount_count(&db->db_holds)); +} + +void * +dmu_buf_set_user(dmu_buf_t *db_fake, void *user_ptr, void *user_data_ptr_ptr, + dmu_buf_evict_func_t *evict_func) +{ + return (dmu_buf_update_user(db_fake, NULL, user_ptr, + user_data_ptr_ptr, evict_func)); +} + +void * +dmu_buf_set_user_ie(dmu_buf_t *db_fake, void *user_ptr, void *user_data_ptr_ptr, + dmu_buf_evict_func_t *evict_func) +{ + dmu_buf_impl_t *db = (dmu_buf_impl_t *)db_fake; + + db->db_immediate_evict = TRUE; + return (dmu_buf_update_user(db_fake, NULL, user_ptr, + user_data_ptr_ptr, evict_func)); +} + +void * +dmu_buf_update_user(dmu_buf_t *db_fake, void *old_user_ptr, void *user_ptr, + void *user_data_ptr_ptr, dmu_buf_evict_func_t *evict_func) +{ + dmu_buf_impl_t *db = (dmu_buf_impl_t *)db_fake; + ASSERT(db->db_level == 0); + + ASSERT((user_ptr == NULL) == (evict_func == NULL)); + + mutex_enter(&db->db_mtx); + + if (db->db_user_ptr == old_user_ptr) { + db->db_user_ptr = user_ptr; + db->db_user_data_ptr_ptr = user_data_ptr_ptr; + db->db_evict_func = evict_func; + + dbuf_update_data(db); + } else { + old_user_ptr = db->db_user_ptr; + } + + mutex_exit(&db->db_mtx); + return (old_user_ptr); +} + +void * +dmu_buf_get_user(dmu_buf_t *db_fake) +{ + dmu_buf_impl_t *db = (dmu_buf_impl_t *)db_fake; + ASSERT(!refcount_is_zero(&db->db_holds)); + + return (db->db_user_ptr); +} + +static void +dbuf_check_blkptr(dnode_t *dn, dmu_buf_impl_t *db) +{ + /* ASSERT(dmu_tx_is_syncing(tx) */ + ASSERT(MUTEX_HELD(&db->db_mtx)); + + if (db->db_blkptr != NULL) + return; + + if (db->db_level == dn->dn_phys->dn_nlevels-1) { + /* + * This buffer was allocated at a time when there was + * no available blkptrs from the dnode, or it was + * inappropriate to hook it in (i.e., nlevels mis-match). + */ + ASSERT(db->db_blkid < dn->dn_phys->dn_nblkptr); + ASSERT(db->db_parent == NULL); + db->db_parent = dn->dn_dbuf; + db->db_blkptr = &dn->dn_phys->dn_blkptr[db->db_blkid]; + DBUF_VERIFY(db); + } else { + dmu_buf_impl_t *parent = db->db_parent; + int epbs = dn->dn_phys->dn_indblkshift - SPA_BLKPTRSHIFT; + + ASSERT(dn->dn_phys->dn_nlevels > 1); + if (parent == NULL) { + mutex_exit(&db->db_mtx); + rw_enter(&dn->dn_struct_rwlock, RW_READER); + (void) dbuf_hold_impl(dn, db->db_level+1, + db->db_blkid >> epbs, FALSE, db, &parent); + rw_exit(&dn->dn_struct_rwlock); + mutex_enter(&db->db_mtx); + db->db_parent = parent; + } + db->db_blkptr = (blkptr_t *)parent->db.db_data + + (db->db_blkid & ((1ULL << epbs) - 1)); + DBUF_VERIFY(db); + } +} + +static void +dbuf_sync_indirect(dbuf_dirty_record_t *dr, dmu_tx_t *tx) +{ + dmu_buf_impl_t *db = dr->dr_dbuf; + dnode_t *dn = db->db_dnode; + zio_t *zio; + + ASSERT(dmu_tx_is_syncing(tx)); + + dprintf_dbuf_bp(db, db->db_blkptr, "blkptr=%p", db->db_blkptr); + + mutex_enter(&db->db_mtx); + + ASSERT(db->db_level > 0); + DBUF_VERIFY(db); + + if (db->db_buf == NULL) { + mutex_exit(&db->db_mtx); + (void) dbuf_read(db, NULL, DB_RF_MUST_SUCCEED); + mutex_enter(&db->db_mtx); + } + ASSERT3U(db->db_state, ==, DB_CACHED); + ASSERT3U(db->db.db_size, ==, 1<<dn->dn_phys->dn_indblkshift); + ASSERT(db->db_buf != NULL); + + dbuf_check_blkptr(dn, db); + + db->db_data_pending = dr; + + mutex_exit(&db->db_mtx); + dbuf_write(dr, db->db_buf, tx); + + zio = dr->dr_zio; + mutex_enter(&dr->dt.di.dr_mtx); + dbuf_sync_list(&dr->dt.di.dr_children, tx); + ASSERT(list_head(&dr->dt.di.dr_children) == NULL); + mutex_exit(&dr->dt.di.dr_mtx); + zio_nowait(zio); +} + +static void +dbuf_sync_leaf(dbuf_dirty_record_t *dr, dmu_tx_t *tx) +{ + arc_buf_t **datap = &dr->dt.dl.dr_data; + dmu_buf_impl_t *db = dr->dr_dbuf; + dnode_t *dn = db->db_dnode; + objset_impl_t *os = dn->dn_objset; + uint64_t txg = tx->tx_txg; + int blksz; + + ASSERT(dmu_tx_is_syncing(tx)); + + dprintf_dbuf_bp(db, db->db_blkptr, "blkptr=%p", db->db_blkptr); + + mutex_enter(&db->db_mtx); + /* + * To be synced, we must be dirtied. But we + * might have been freed after the dirty. + */ + if (db->db_state == DB_UNCACHED) { + /* This buffer has been freed since it was dirtied */ + ASSERT(db->db.db_data == NULL); + } else if (db->db_state == DB_FILL) { + /* This buffer was freed and is now being re-filled */ + ASSERT(db->db.db_data != dr->dt.dl.dr_data); + } else { + ASSERT(db->db_state == DB_CACHED || db->db_state == DB_NOFILL); + } + DBUF_VERIFY(db); + + /* + * If this is a bonus buffer, simply copy the bonus data into the + * dnode. It will be written out when the dnode is synced (and it + * will be synced, since it must have been dirty for dbuf_sync to + * be called). + */ + if (db->db_blkid == DB_BONUS_BLKID) { + dbuf_dirty_record_t **drp; + + ASSERT(*datap != NULL); + ASSERT3U(db->db_level, ==, 0); + ASSERT3U(dn->dn_phys->dn_bonuslen, <=, DN_MAX_BONUSLEN); + bcopy(*datap, DN_BONUS(dn->dn_phys), dn->dn_phys->dn_bonuslen); + if (*datap != db->db.db_data) { + zio_buf_free(*datap, DN_MAX_BONUSLEN); + arc_space_return(DN_MAX_BONUSLEN); + } + db->db_data_pending = NULL; + drp = &db->db_last_dirty; + while (*drp != dr) + drp = &(*drp)->dr_next; + ASSERT(dr->dr_next == NULL); + *drp = dr->dr_next; + kmem_free(dr, sizeof (dbuf_dirty_record_t)); + ASSERT(db->db_dirtycnt > 0); + db->db_dirtycnt -= 1; + mutex_exit(&db->db_mtx); + dbuf_rele(db, (void *)(uintptr_t)txg); + return; + } + + /* + * This function may have dropped the db_mtx lock allowing a dmu_sync + * operation to sneak in. As a result, we need to ensure that we + * don't check the dr_override_state until we have returned from + * dbuf_check_blkptr. + */ + dbuf_check_blkptr(dn, db); + + /* + * If this buffer is in the middle of an immdiate write, + * wait for the synchronous IO to complete. + */ + while (dr->dt.dl.dr_override_state == DR_IN_DMU_SYNC) { + ASSERT(dn->dn_object != DMU_META_DNODE_OBJECT); + cv_wait(&db->db_changed, &db->db_mtx); + ASSERT(dr->dt.dl.dr_override_state != DR_NOT_OVERRIDDEN); + } + + /* + * If this dbuf has already been written out via an immediate write, + * just complete the write by copying over the new block pointer and + * updating the accounting via the write-completion functions. + */ + if (dr->dt.dl.dr_override_state == DR_OVERRIDDEN) { + zio_t zio_fake; + + zio_fake.io_private = &db; + zio_fake.io_error = 0; + zio_fake.io_bp = db->db_blkptr; + zio_fake.io_bp_orig = *db->db_blkptr; + zio_fake.io_txg = txg; + zio_fake.io_flags = 0; + + *db->db_blkptr = dr->dt.dl.dr_overridden_by; + dr->dt.dl.dr_override_state = DR_NOT_OVERRIDDEN; + db->db_data_pending = dr; + dr->dr_zio = &zio_fake; + mutex_exit(&db->db_mtx); + + ASSERT(!DVA_EQUAL(BP_IDENTITY(zio_fake.io_bp), + BP_IDENTITY(&zio_fake.io_bp_orig)) || + BP_IS_HOLE(zio_fake.io_bp)); + + if (BP_IS_OLDER(&zio_fake.io_bp_orig, txg)) + (void) dsl_dataset_block_kill(os->os_dsl_dataset, + &zio_fake.io_bp_orig, dn->dn_zio, tx); + + dbuf_write_ready(&zio_fake, db->db_buf, db); + dbuf_write_done(&zio_fake, db->db_buf, db); + + return; + } + + if (db->db_state != DB_NOFILL) { + blksz = arc_buf_size(*datap); + + if (dn->dn_object != DMU_META_DNODE_OBJECT) { + /* + * If this buffer is currently "in use" (i.e., there + * are active holds and db_data still references it), + * then make a copy before we start the write so that + * any modifications from the open txg will not leak + * into this write. + * + * NOTE: this copy does not need to be made for + * objects only modified in the syncing context (e.g. + * DNONE_DNODE blocks). + */ + if (refcount_count(&db->db_holds) > 1 && + *datap == db->db_buf) { + arc_buf_contents_t type = + DBUF_GET_BUFC_TYPE(db); + *datap = + arc_buf_alloc(os->os_spa, blksz, db, type); + bcopy(db->db.db_data, (*datap)->b_data, blksz); + } + } + + ASSERT(*datap != NULL); + } + db->db_data_pending = dr; + + mutex_exit(&db->db_mtx); + + dbuf_write(dr, *datap, tx); + + ASSERT(!list_link_active(&dr->dr_dirty_node)); + if (dn->dn_object == DMU_META_DNODE_OBJECT) + list_insert_tail(&dn->dn_dirty_records[txg&TXG_MASK], dr); + else + zio_nowait(dr->dr_zio); +} + +void +dbuf_sync_list(list_t *list, dmu_tx_t *tx) +{ + dbuf_dirty_record_t *dr; + + while (dr = list_head(list)) { + if (dr->dr_zio != NULL) { + /* + * If we find an already initialized zio then we + * are processing the meta-dnode, and we have finished. + * The dbufs for all dnodes are put back on the list + * during processing, so that we can zio_wait() + * these IOs after initiating all child IOs. + */ + ASSERT3U(dr->dr_dbuf->db.db_object, ==, + DMU_META_DNODE_OBJECT); + break; + } + list_remove(list, dr); + if (dr->dr_dbuf->db_level > 0) + dbuf_sync_indirect(dr, tx); + else + dbuf_sync_leaf(dr, tx); + } +} + +static void +dbuf_write(dbuf_dirty_record_t *dr, arc_buf_t *data, dmu_tx_t *tx) +{ + dmu_buf_impl_t *db = dr->dr_dbuf; + dnode_t *dn = db->db_dnode; + objset_impl_t *os = dn->dn_objset; + dmu_buf_impl_t *parent = db->db_parent; + uint64_t txg = tx->tx_txg; + zbookmark_t zb; + writeprops_t wp = { 0 }; + zio_t *zio; + + if (!BP_IS_HOLE(db->db_blkptr) && + (db->db_level > 0 || dn->dn_type == DMU_OT_DNODE)) { + /* + * Private object buffers are released here rather + * than in dbuf_dirty() since they are only modified + * in the syncing context and we don't want the + * overhead of making multiple copies of the data. + */ + arc_release(data, db); + } else if (db->db_state != DB_NOFILL) { + ASSERT(arc_released(data)); + /* XXX why do we need to thaw here? */ + arc_buf_thaw(data); + } + + if (parent != dn->dn_dbuf) { + ASSERT(parent && parent->db_data_pending); + ASSERT(db->db_level == parent->db_level-1); + ASSERT(arc_released(parent->db_buf)); + zio = parent->db_data_pending->dr_zio; + } else { + ASSERT(db->db_level == dn->dn_phys->dn_nlevels-1); + ASSERT3P(db->db_blkptr, ==, + &dn->dn_phys->dn_blkptr[db->db_blkid]); + zio = dn->dn_zio; + } + + ASSERT(db->db_level == 0 || data == db->db_buf); + ASSERT3U(db->db_blkptr->blk_birth, <=, txg); + ASSERT(zio); + + zb.zb_objset = os->os_dsl_dataset ? os->os_dsl_dataset->ds_object : 0; + zb.zb_object = db->db.db_object; + zb.zb_level = db->db_level; + zb.zb_blkid = db->db_blkid; + + wp.wp_type = dn->dn_type; + wp.wp_level = db->db_level; + wp.wp_copies = os->os_copies; + wp.wp_dncompress = dn->dn_compress; + wp.wp_oscompress = os->os_compress; + wp.wp_dnchecksum = dn->dn_checksum; + wp.wp_oschecksum = os->os_checksum; + + if (BP_IS_OLDER(db->db_blkptr, txg)) + (void) dsl_dataset_block_kill( + os->os_dsl_dataset, db->db_blkptr, zio, tx); + + if (db->db_state == DB_NOFILL) { + zio_prop_t zp = { 0 }; + + write_policy(os->os_spa, &wp, &zp); + dr->dr_zio = zio_write(zio, os->os_spa, + txg, db->db_blkptr, NULL, + db->db.db_size, &zp, dbuf_skip_write_ready, + dbuf_skip_write_done, db, ZIO_PRIORITY_ASYNC_WRITE, + ZIO_FLAG_MUSTSUCCEED, &zb); + } else { + dr->dr_zio = arc_write(zio, os->os_spa, &wp, + DBUF_IS_L2CACHEABLE(db), txg, db->db_blkptr, + data, dbuf_write_ready, dbuf_write_done, db, + ZIO_PRIORITY_ASYNC_WRITE, ZIO_FLAG_MUSTSUCCEED, &zb); + } +} + +/* wrapper function for dbuf_write_ready bypassing ARC */ +static void +dbuf_skip_write_ready(zio_t *zio) +{ + blkptr_t *bp = zio->io_bp; + + if (!BP_IS_GANG(bp)) + zio_skip_write(zio); + + dbuf_write_ready(zio, NULL, zio->io_private); +} + +/* wrapper function for dbuf_write_done bypassing ARC */ +static void +dbuf_skip_write_done(zio_t *zio) +{ + dbuf_write_done(zio, NULL, zio->io_private); +} + +/* ARGSUSED */ +static void +dbuf_write_ready(zio_t *zio, arc_buf_t *buf, void *vdb) +{ + dmu_buf_impl_t *db = vdb; + dnode_t *dn = db->db_dnode; + objset_impl_t *os = dn->dn_objset; + blkptr_t *bp = zio->io_bp; + blkptr_t *bp_orig = &zio->io_bp_orig; + uint64_t fill = 0; + int old_size, new_size, i; + + ASSERT(db->db_blkptr == bp); + + dprintf_dbuf_bp(db, bp_orig, "bp_orig: %s", ""); + + old_size = bp_get_dasize(os->os_spa, bp_orig); + new_size = bp_get_dasize(os->os_spa, bp); + + dnode_diduse_space(dn, new_size - old_size); + + if (BP_IS_HOLE(bp)) { + dsl_dataset_t *ds = os->os_dsl_dataset; + dmu_tx_t *tx = os->os_synctx; + + if (bp_orig->blk_birth == tx->tx_txg) + (void) dsl_dataset_block_kill(ds, bp_orig, zio, tx); + ASSERT3U(bp->blk_fill, ==, 0); + return; + } + + ASSERT(BP_GET_TYPE(bp) == dn->dn_type); + ASSERT(BP_GET_LEVEL(bp) == db->db_level); + + mutex_enter(&db->db_mtx); + + if (db->db_level == 0) { + mutex_enter(&dn->dn_mtx); + if (db->db_blkid > dn->dn_phys->dn_maxblkid) + dn->dn_phys->dn_maxblkid = db->db_blkid; + mutex_exit(&dn->dn_mtx); + + if (dn->dn_type == DMU_OT_DNODE) { + dnode_phys_t *dnp = db->db.db_data; + for (i = db->db.db_size >> DNODE_SHIFT; i > 0; + i--, dnp++) { + if (dnp->dn_type != DMU_OT_NONE) + fill++; + } + } else { + fill = 1; + } + } else { + blkptr_t *ibp = db->db.db_data; + ASSERT3U(db->db.db_size, ==, 1<<dn->dn_phys->dn_indblkshift); + for (i = db->db.db_size >> SPA_BLKPTRSHIFT; i > 0; i--, ibp++) { + if (BP_IS_HOLE(ibp)) + continue; + ASSERT3U(BP_GET_LSIZE(ibp), ==, + db->db_level == 1 ? dn->dn_datablksz : + (1<<dn->dn_phys->dn_indblkshift)); + fill += ibp->blk_fill; + } + } + + bp->blk_fill = fill; + + mutex_exit(&db->db_mtx); + + if (zio->io_flags & ZIO_FLAG_IO_REWRITE) { + ASSERT(DVA_EQUAL(BP_IDENTITY(bp), BP_IDENTITY(bp_orig))); + } else { + dsl_dataset_t *ds = os->os_dsl_dataset; + dmu_tx_t *tx = os->os_synctx; + + if (bp_orig->blk_birth == tx->tx_txg) + (void) dsl_dataset_block_kill(ds, bp_orig, zio, tx); + dsl_dataset_block_born(ds, bp, tx); + } +} + +/* ARGSUSED */ +static void +dbuf_write_done(zio_t *zio, arc_buf_t *buf, void *vdb) +{ + dmu_buf_impl_t *db = vdb; + uint64_t txg = zio->io_txg; + dbuf_dirty_record_t **drp, *dr; + + ASSERT3U(zio->io_error, ==, 0); + + mutex_enter(&db->db_mtx); + + drp = &db->db_last_dirty; + while ((dr = *drp) != db->db_data_pending) + drp = &dr->dr_next; + ASSERT(!list_link_active(&dr->dr_dirty_node)); + ASSERT(dr->dr_txg == txg); + ASSERT(dr->dr_next == NULL); + *drp = dr->dr_next; + + if (db->db_level == 0) { + ASSERT(db->db_blkid != DB_BONUS_BLKID); + ASSERT(dr->dt.dl.dr_override_state == DR_NOT_OVERRIDDEN); + + if (db->db_state != DB_NOFILL) { + if (dr->dt.dl.dr_data != db->db_buf) + VERIFY(arc_buf_remove_ref(dr->dt.dl.dr_data, + db) == 1); + else if (!BP_IS_HOLE(db->db_blkptr)) + arc_set_callback(db->db_buf, dbuf_do_evict, db); + else + ASSERT(arc_released(db->db_buf)); + } + } else { + dnode_t *dn = db->db_dnode; + + ASSERT(list_head(&dr->dt.di.dr_children) == NULL); + ASSERT3U(db->db.db_size, ==, 1<<dn->dn_phys->dn_indblkshift); + if (!BP_IS_HOLE(db->db_blkptr)) { + int epbs = + dn->dn_phys->dn_indblkshift - SPA_BLKPTRSHIFT; + ASSERT3U(BP_GET_LSIZE(db->db_blkptr), ==, + db->db.db_size); + ASSERT3U(dn->dn_phys->dn_maxblkid + >> (db->db_level * epbs), >=, db->db_blkid); + arc_set_callback(db->db_buf, dbuf_do_evict, db); + } + mutex_destroy(&dr->dt.di.dr_mtx); + list_destroy(&dr->dt.di.dr_children); + } + kmem_free(dr, sizeof (dbuf_dirty_record_t)); + + cv_broadcast(&db->db_changed); + ASSERT(db->db_dirtycnt > 0); + db->db_dirtycnt -= 1; + db->db_data_pending = NULL; + mutex_exit(&db->db_mtx); + + dprintf_dbuf_bp(db, zio->io_bp, "bp: %s", ""); + + dbuf_rele(db, (void *)(uintptr_t)txg); +} |