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/*
* 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 (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
* Copyright 2011 Nexenta Systems, Inc. All rights reserved.
*/
#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>
#include <sys/sa.h>
#include <sys/sa_impl.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);
/*
* 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_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_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;
}
boolean_t
dbuf_is_metadata(dmu_buf_impl_t *db)
{
if (db->db_level > 0) {
return (B_TRUE);
} else {
boolean_t is_metadata;
DB_DNODE_ENTER(db);
is_metadata = dmu_ot[DB_DNODE(db)->dn_type].ot_metadata;
DB_DNODE_EXIT(db);
return (is_metadata);
}
}
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 < (uint64_t)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;
dbuf_dirty_record_t *dr;
ASSERT(MUTEX_HELD(&db->db_mtx));
if (!(zfs_flags & ZFS_DEBUG_DBUF_VERIFY))
return;
ASSERT(db->db_objset != NULL);
DB_DNODE_ENTER(db);
dn = DB_DNODE(db);
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 == DMU_BONUS_BLKID ||
db->db_blkid == DMU_SPILL_BLKID ||
!list_is_empty(&dn->dn_dbufs));
}
if (db->db_blkid == DMU_BONUS_BLKID) {
ASSERT(dn != NULL);
ASSERT3U(db->db.db_size, >=, dn->dn_bonuslen);
ASSERT3U(db->db.db_offset, ==, DMU_BONUS_BLKID);
} else if (db->db_blkid == DMU_SPILL_BLKID) {
ASSERT(dn != NULL);
ASSERT3U(db->db.db_size, >=, dn->dn_bonuslen);
ASSERT3U(db->db.db_offset, ==, 0);
} else {
ASSERT3U(db->db.db_offset, ==, db->db_blkid * db->db.db_size);
}
for (dr = db->db_data_pending; dr != NULL; dr = dr->dr_next)
ASSERT(dr->dr_dbuf == db);
for (dr = db->db_last_dirty; dr != NULL; dr = dr->dr_next)
ASSERT(dr->dr_dbuf == db);
/*
* 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) {
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 (DMU_OBJECT_IS_SPECIAL(db->db.db_object))
ASSERT(db->db_parent == NULL);
else
ASSERT(db->db_parent != NULL);
if (db->db_blkid != DMU_SPILL_BLKID)
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(&dn->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_buf == NULL || db->db_buf->b_data) &&
db->db.db_data && db->db_blkid != DMU_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);
}
}
}
DB_DNODE_EXIT(db);
}
#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;
}
}
/*
* Loan out an arc_buf for read. Return the loaned arc_buf.
*/
arc_buf_t *
dbuf_loan_arcbuf(dmu_buf_impl_t *db)
{
arc_buf_t *abuf;
mutex_enter(&db->db_mtx);
if (arc_released(db->db_buf) || refcount_count(&db->db_holds) > 1) {
int blksz = db->db.db_size;
spa_t *spa;
mutex_exit(&db->db_mtx);
DB_GET_SPA(&spa, db);
abuf = arc_loan_buf(spa, blksz);
bcopy(db->db.db_data, abuf->b_data, blksz);
} else {
abuf = db->db_buf;
arc_loan_inuse_buf(abuf, db);
dbuf_set_data(db, NULL);
mutex_exit(&db->db_mtx);
}
return (abuf);
}
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 != DMU_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);
dbuf_rele_and_unlock(db, NULL);
}
static void
dbuf_read_impl(dmu_buf_impl_t *db, zio_t *zio, uint32_t *flags)
{
dnode_t *dn;
spa_t *spa;
zbookmark_t zb;
uint32_t aflags = ARC_NOWAIT;
arc_buf_t *pbuf;
DB_DNODE_ENTER(db);
dn = DB_DNODE(db);
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 == DMU_BONUS_BLKID) {
int bonuslen = MIN(dn->dn_bonuslen, dn->dn_phys->dn_bonuslen);
ASSERT3U(bonuslen, <=, db->db.db_size);
db->db.db_data = zio_buf_alloc(DN_MAX_BONUSLEN);
arc_space_consume(DN_MAX_BONUSLEN, ARC_SPACE_OTHER);
if (bonuslen < DN_MAX_BONUSLEN)
bzero(db->db.db_data, DN_MAX_BONUSLEN);
if (bonuslen)
bcopy(DN_BONUS(dn->dn_phys), db->db.db_data, bonuslen);
DB_DNODE_EXIT(db);
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));
DB_DNODE_EXIT(db);
bzero(db->db.db_data, db->db.db_size);
db->db_state = DB_CACHED;
*flags |= DB_RF_CACHED;
mutex_exit(&db->db_mtx);
return;
}
spa = dn->dn_objset->os_spa;
DB_DNODE_EXIT(db);
db->db_state = DB_READ;
mutex_exit(&db->db_mtx);
if (DBUF_IS_L2CACHEABLE(db))
aflags |= ARC_L2CACHE;
SET_BOOKMARK(&zb, db->db_objset->os_dsl_dataset ?
db->db_objset->os_dsl_dataset->ds_object : DMU_META_OBJSET,
db->db.db_object, db->db_level, 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) dsl_read(zio, 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;
dnode_t *dn;
/*
* 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);
DB_DNODE_ENTER(db);
dn = DB_DNODE(db);
if ((flags & DB_RF_HAVESTRUCT) == 0)
rw_enter(&dn->dn_struct_rwlock, RW_READER);
prefetch = db->db_level == 0 && db->db_blkid != DMU_BONUS_BLKID &&
(flags & DB_RF_NOPREFETCH) == 0 && dn != 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(&dn->dn_zfetch, db->db.db_offset,
db->db.db_size, TRUE);
if ((flags & DB_RF_HAVESTRUCT) == 0)
rw_exit(&dn->dn_struct_rwlock);
DB_DNODE_EXIT(db);
} else if (db->db_state == DB_UNCACHED) {
spa_t *spa = dn->dn_objset->os_spa;
if (zio == NULL)
zio = zio_root(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(&dn->dn_zfetch, db->db.db_offset,
db->db.db_size, flags & DB_RF_CACHED);
if ((flags & DB_RF_HAVESTRUCT) == 0)
rw_exit(&dn->dn_struct_rwlock);
DB_DNODE_EXIT(db);
if (!havepzio)
err = zio_wait(zio);
} else {
mutex_exit(&db->db_mtx);
if (prefetch)
dmu_zfetch(&dn->dn_zfetch, db->db.db_offset,
db->db.db_size, TRUE);
if ((flags & DB_RF_HAVESTRUCT) == 0)
rw_exit(&dn->dn_struct_rwlock);
DB_DNODE_EXIT(db);
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 != DMU_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);
spa_t *spa;
ASSERT(db->db_buf == NULL);
ASSERT(db->db.db_data == NULL);
DB_GET_SPA(&spa, db);
dbuf_set_data(db, arc_buf_alloc(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 == DMU_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 == DMU_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, ARC_SPACE_OTHER);
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);
spa_t *spa;
DB_GET_SPA(&spa, db);
dr->dt.dl.dr_data = arc_buf_alloc(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;
blkptr_t *bp = &dr->dt.dl.dr_overridden_by;
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 == DMU_BONUS_BLKID ||
dr->dt.dl.dr_override_state == DR_NOT_OVERRIDDEN)
return;
ASSERT(db->db_data_pending != dr);
/* free this block */
if (!BP_IS_HOLE(bp)) {
spa_t *spa;
DB_GET_SPA(&spa, db);
zio_free(spa, txg, bp);
}
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 != DMU_SPILL_BLKID)) {
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 != DMU_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 != DMU_SPILL_BLKID &&
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.
* Don't pass the bp to dsl_dataset_block_freeable() since we
* are holding the db_mtx lock and might deadlock if we are
* prefetching a dedup-ed block.
*/
if (birth_txg)
return (ds == NULL ||
dsl_dataset_block_freeable(ds, NULL, 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);
dnode_t *dn;
ASSERT(db->db_blkid != DMU_BONUS_BLKID);
DB_DNODE_ENTER(db);
dn = DB_DNODE(db);
/* XXX does *this* func really need the lock? */
ASSERT(RW_WRITE_HELD(&dn->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(dn->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(dn, size-osize, tx);
DB_DNODE_EXIT(db);
}
void
dbuf_release_bp(dmu_buf_impl_t *db)
{
objset_t *os;
zbookmark_t zb;
DB_GET_OBJSET(&os, db);
ASSERT(dsl_pool_sync_context(dmu_objset_pool(os)));
ASSERT(arc_released(os->os_phys_buf) ||
list_link_active(&os->os_dsl_dataset->ds_synced_link));
ASSERT(db->db_parent == NULL || arc_released(db->db_parent->db_buf));
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;
(void) arc_release_bp(db->db_buf, db,
db->db_blkptr, os->os_spa, &zb);
}
dbuf_dirty_record_t *
dbuf_dirty(dmu_buf_impl_t *db, dmu_tx_t *tx)
{
dnode_t *dn;
objset_t *os;
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);
DB_DNODE_ENTER(db);
dn = DB_DNODE(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.
*/
ASSERT(!dmu_tx_is_syncing(tx) ||
BP_IS_HOLE(dn->dn_objset->os_rootbp) ||
DMU_OBJECT_IS_SPECIAL(dn->dn_object) ||
dn->dn_objset->os_dsl_dataset == NULL);
/*
* 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 (db->db_blkid == DMU_SPILL_BLKID)
dn->dn_have_spill = B_TRUE;
/*
* 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) {
DB_DNODE_EXIT(db);
if (db->db_level == 0 && db->db_blkid != DMU_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 &&
db->db_state != DB_NOFILL)
arc_buf_thaw(db->db_buf);
}
mutex_exit(&db->db_mtx);
return (dr);
}
/*
* Only valid if not already dirty.
*/
ASSERT(dn->dn_object == 0 ||
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 or we're initializing the os or it's a special object.
* 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.
*/
os = dn->dn_objset;
ASSERT(!dmu_tx_is_syncing(tx) || DMU_OBJECT_IS_SPECIAL(dn->dn_object) ||
os->os_dsl_dataset == NULL || 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 != DMU_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_dsize() 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 == DMU_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 != DMU_BONUS_BLKID &&
db->db_blkid != DMU_SPILL_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 == DMU_BONUS_BLKID ||
db->db_blkid == DMU_SPILL_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);
DB_DNODE_EXIT(db);
return (dr);
} else if (do_free_accounting) {
blkptr_t *bp = db->db_blkptr;
int64_t willfree = (bp && !BP_IS_HOLE(bp)) ?
bp_get_dsize(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.
*/
ddt_prefetch(os->os_spa, bp);
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);
ASSERT(parent != NULL);
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 == dn->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);
DB_DNODE_EXIT(db);
return (dr);
}
static int
dbuf_undirty(dmu_buf_impl_t *db, dmu_tx_t *tx)
{
dnode_t *dn;
uint64_t txg = tx->tx_txg;
dbuf_dirty_record_t *dr, **drp;
ASSERT(txg != 0);
ASSERT(db->db_blkid != DMU_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);
ASSERT(dr->dr_dbuf == db);
DB_DNODE_ENTER(db);
dn = DB_DNODE(db);
/*
* 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.
* Also note: we can get here with a spill block, so
* test for that similar to how dbuf_dirty does.
*/
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 */
if (db->db_blkid != DMU_SPILL_BLKID) {
mutex_enter(&dn->dn_mtx);
dnode_clear_range(dn, db->db_blkid, 1, tx);
mutex_exit(&dn->dn_mtx);
}
DB_DNODE_EXIT(db);
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;
/*
* Note that there are three places in dbuf_dirty()
* where this dirty record may be put on a list.
* Make sure to do a list_remove corresponding to
* every one of those list_insert calls.
*/
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_blkid == DMU_SPILL_BLKID ||
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);
}
DB_DNODE_EXIT(db);
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(db->db_state == DB_NOFILL || 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));
DB_DNODE_ENTER(db);
if (RW_WRITE_HELD(&DB_DNODE(db)->dn_struct_rwlock))
rf |= DB_RF_HAVESTRUCT;
DB_DNODE_EXIT(db);
(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 != DMU_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 != DMU_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);
}
/*
* Directly assign a provided arc buf to a given dbuf if it's not referenced
* by anybody except our caller. Otherwise copy arcbuf's contents to dbuf.
*/
void
dbuf_assign_arcbuf(dmu_buf_impl_t *db, arc_buf_t *buf, dmu_tx_t *tx)
{
ASSERT(!refcount_is_zero(&db->db_holds));
ASSERT(db->db_blkid != DMU_BONUS_BLKID);
ASSERT(db->db_level == 0);
ASSERT(DBUF_GET_BUFC_TYPE(db) == ARC_BUFC_DATA);
ASSERT(buf != NULL);
ASSERT(arc_buf_size(buf) == db->db.db_size);
ASSERT(tx->tx_txg != 0);
arc_return_buf(buf, db);
ASSERT(arc_released(buf));
mutex_enter(&db->db_mtx);
while (db->db_state == DB_READ || db->db_state == DB_FILL)
cv_wait(&db->db_changed, &db->db_mtx);
ASSERT(db->db_state == DB_CACHED || db->db_state == DB_UNCACHED);
if (db->db_state == DB_CACHED &&
refcount_count(&db->db_holds) - 1 > db->db_dirtycnt) {
mutex_exit(&db->db_mtx);
(void) dbuf_dirty(db, tx);
bcopy(buf->b_data, db->db.db_data, db->db.db_size);
VERIFY(arc_buf_remove_ref(buf, db) == 1);
xuio_stat_wbuf_copied();
return;
}
xuio_stat_wbuf_nocopy();
if (db->db_state == DB_CACHED) {
dbuf_dirty_record_t *dr = db->db_last_dirty;
ASSERT(db->db_buf != NULL);
if (dr != NULL && dr->dr_txg == tx->tx_txg) {
ASSERT(dr->dt.dl.dr_data == db->db_buf);
if (!arc_released(db->db_buf)) {
ASSERT(dr->dt.dl.dr_override_state ==
DR_OVERRIDDEN);
arc_release(db->db_buf, db);
}
dr->dt.dl.dr_data = buf;
VERIFY(arc_buf_remove_ref(db->db_buf, db) == 1);
} else if (dr == NULL || dr->dt.dl.dr_data != db->db_buf) {
arc_release(db->db_buf, db);
VERIFY(arc_buf_remove_ref(db->db_buf, db) == 1);
}
db->db_buf = NULL;
}
ASSERT(db->db_buf == NULL);
dbuf_set_data(db, buf);
db->db_state = DB_FILL;
mutex_exit(&db->db_mtx);
(void) dbuf_dirty(db, tx);
dbuf_fill_done(db, tx);
}
/*
* "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;
dmu_buf_impl_t *parent = db->db_parent;
dmu_buf_impl_t *dndb;
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 == DMU_BONUS_BLKID) {
zio_buf_free(db->db.db_data, DN_MAX_BONUSLEN);
arc_space_return(DN_MAX_BONUSLEN, ARC_SPACE_OTHER);
}
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;
DB_DNODE_ENTER(db);
dn = DB_DNODE(db);
dndb = dn->dn_dbuf;
if (db->db_blkid != DMU_BONUS_BLKID && MUTEX_HELD(&dn->dn_dbufs_mtx)) {
list_remove(&dn->dn_dbufs, db);
(void) atomic_dec_32_nv(&dn->dn_dbufs_count);
membar_producer();
DB_DNODE_EXIT(db);
/*
* Decrementing the dbuf count means that the hold corresponding
* to the removed dbuf is no longer discounted in dnode_move(),
* so the dnode cannot be moved until after we release the hold.
* The membar_producer() ensures visibility of the decremented
* value in dnode_move(), since DB_DNODE_EXIT doesn't actually
* release any lock.
*/
dnode_rele(dn, db);
db->db_dnode_handle = NULL;
} else {
DB_DNODE_EXIT(db);
}
if (db->db_buf)
dbuf_gone = arc_buf_evict(db->db_buf);
if (!dbuf_gone)
mutex_exit(&db->db_mtx);
/*
* If this dbuf is referenced 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 != DMU_BONUS_BLKID);
if (blkid == DMU_SPILL_BLKID) {
mutex_enter(&dn->dn_mtx);
if (dn->dn_have_spill &&
(dn->dn_phys->dn_flags & DNODE_FLAG_SPILL_BLKPTR))
*bpp = &dn->dn_phys->dn_spill;
else
*bpp = NULL;
dbuf_add_ref(dn->dn_dbuf, NULL);
*parentp = dn->dn_dbuf;
mutex_exit(&dn->dn_mtx);
return (0);
}
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_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_handle = dn->dn_handle;
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 == DMU_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 = DMU_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), ARC_SPACE_OTHER);
return (db);
} else if (blkid == DMU_SPILL_BLKID) {
db->db.db_size = (blkptr != NULL) ?
BP_GET_LSIZE(blkptr) : SPA_MINBLOCKSIZE;
db->db.db_offset = 0;
} 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), ARC_SPACE_OTHER);
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);
(void) atomic_inc_32_nv(&dn->dn_dbufs_count);
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 != DMU_BONUS_BLKID) {
/*
* If this dbuf is still on the dn_dbufs list,
* remove it from that list.
*/
if (db->db_dnode_handle != NULL) {
dnode_t *dn;
DB_DNODE_ENTER(db);
dn = DB_DNODE(db);
mutex_enter(&dn->dn_dbufs_mtx);
list_remove(&dn->dn_dbufs, db);
(void) atomic_dec_32_nv(&dn->dn_dbufs_count);
mutex_exit(&dn->dn_dbufs_mtx);
DB_DNODE_EXIT(db);
/*
* Decrementing the dbuf count means that the hold
* corresponding to the removed dbuf is no longer
* discounted in dnode_move(), so the dnode cannot be
* moved until after we release the hold.
*/
dnode_rele(dn, db);
db->db_dnode_handle = 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), ARC_SPACE_OTHER);
}
void
dbuf_prefetch(dnode_t *dn, uint64_t blkid)
{
dmu_buf_impl_t *db = NULL;
blkptr_t *bp = NULL;
ASSERT(blkid != DMU_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)) {
/*
* This dbuf is already in the cache. We assume that
* it is already CACHED, or else about to be either
* read or filled.
*/
mutex_exit(&db->db_mtx);
return;
}
if (dbuf_findbp(dn, 0, blkid, TRUE, &db, &bp) == 0) {
if (bp && !BP_IS_HOLE(bp)) {
int priority = dn->dn_type == DMU_OT_DDT_ZAP ?
ZIO_PRIORITY_DDT_PREFETCH : ZIO_PRIORITY_ASYNC_READ;
arc_buf_t *pbuf;
dsl_dataset_t *ds = dn->dn_objset->os_dsl_dataset;
uint32_t aflags = ARC_NOWAIT | ARC_PREFETCH;
zbookmark_t zb;
SET_BOOKMARK(&zb, ds ? ds->ds_object : DMU_META_OBJSET,
dn->dn_object, 0, blkid);
if (db)
pbuf = db->db_buf;
else
pbuf = dn->dn_objset->os_phys_buf;
(void) dsl_read(NULL, dn->dn_objset->os_spa,
bp, pbuf, NULL, NULL, priority,
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 != DMU_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 != DMU_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(dn->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_DNODE(db), ==, 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, DMU_BONUS_BLKID, dn->dn_dbuf, NULL);
}
int
dbuf_spill_set_blksz(dmu_buf_t *db_fake, uint64_t blksz, dmu_tx_t *tx)
{
dmu_buf_impl_t *db = (dmu_buf_impl_t *)db_fake;
dnode_t *dn;
if (db->db_blkid != DMU_SPILL_BLKID)
return (ENOTSUP);
if (blksz == 0)
blksz = SPA_MINBLOCKSIZE;
if (blksz > SPA_MAXBLOCKSIZE)
blksz = SPA_MAXBLOCKSIZE;
else
blksz = P2ROUNDUP(blksz, SPA_MINBLOCKSIZE);
DB_DNODE_ENTER(db);
dn = DB_DNODE(db);
rw_enter(&dn->dn_struct_rwlock, RW_WRITER);
dbuf_new_size(db, blksz, tx);
rw_exit(&dn->dn_struct_rwlock);
DB_DNODE_EXIT(db);
return (0);
}
void
dbuf_rm_spill(dnode_t *dn, dmu_tx_t *tx)
{
dbuf_free_range(dn, DMU_SPILL_BLKID, DMU_SPILL_BLKID, tx);
}
#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);
}
/*
* If you call dbuf_rele() you had better not be referencing the dnode handle
* unless you have some other direct or indirect hold on the dnode. (An indirect
* hold is a hold on one of the dnode's dbufs, including the bonus buffer.)
* Without that, the dbuf_rele() could lead to a dnode_rele() followed by the
* dnode's parent dbuf evicting its dnode handles.
*/
#pragma weak dmu_buf_rele = dbuf_rele
void
dbuf_rele(dmu_buf_impl_t *db, void *tag)
{
mutex_enter(&db->db_mtx);
dbuf_rele_and_unlock(db, tag);
}
/*
* dbuf_rele() for an already-locked dbuf. This is necessary to allow
* db_dirtycnt and db_holds to be updated atomically.
*/
void
dbuf_rele_and_unlock(dmu_buf_impl_t *db, void *tag)
{
int64_t holds;
ASSERT(MUTEX_HELD(&db->db_mtx));
DBUF_VERIFY(db);
/*
* Remove the reference to the dbuf before removing its hold on the
* dnode so we can guarantee in dnode_move() that a referenced bonus
* buffer has a corresponding dnode hold.
*/
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 == DMU_BONUS_BLKID) {
mutex_exit(&db->db_mtx);
/*
* If the dnode moves here, we cannot cross this barrier
* until the move completes.
*/
DB_DNODE_ENTER(db);
(void) atomic_dec_32_nv(&DB_DNODE(db)->dn_dbufs_count);
DB_DNODE_EXIT(db);
/*
* The bonus buffer's dnode hold is no longer discounted
* in dnode_move(). The dnode cannot move until after
* the dnode_rele().
*/
dnode_rele(DB_DNODE(db), 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);
}
boolean_t
dmu_buf_freeable(dmu_buf_t *dbuf)
{
boolean_t res = B_FALSE;
dmu_buf_impl_t *db = (dmu_buf_impl_t *)dbuf;
if (db->db_blkptr)
res = dsl_dataset_block_freeable(db->db_objset->os_dsl_dataset,
db->db_blkptr, db->db_blkptr->blk_birth);
return (res);
}
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_blkid == DMU_SPILL_BLKID) {
db->db_blkptr = &dn->dn_phys->dn_spill;
BP_ZERO(db->db_blkptr);
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;
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);
ASSERT(db->db_buf != NULL);
DB_DNODE_ENTER(db);
dn = DB_DNODE(db);
ASSERT3U(db->db.db_size, ==, 1<<dn->dn_phys->dn_indblkshift);
dbuf_check_blkptr(dn, db);
DB_DNODE_EXIT(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;
objset_t *os;
uint64_t txg = tx->tx_txg;
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);
DB_DNODE_ENTER(db);
dn = DB_DNODE(db);
if (db->db_blkid == DMU_SPILL_BLKID) {
mutex_enter(&dn->dn_mtx);
dn->dn_phys->dn_flags |= DNODE_FLAG_SPILL_BLKPTR;
mutex_exit(&dn->dn_mtx);
}
/*
* 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 == DMU_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);
DB_DNODE_EXIT(db);
if (*datap != db->db.db_data) {
zio_buf_free(*datap, DN_MAX_BONUSLEN);
arc_space_return(DN_MAX_BONUSLEN, ARC_SPACE_OTHER);
}
db->db_data_pending = NULL;
drp = &db->db_last_dirty;
while (*drp != dr)
drp = &(*drp)->dr_next;
ASSERT(dr->dr_next == NULL);
ASSERT(dr->dr_dbuf == db);
*drp = dr->dr_next;
if (dr->dr_dbuf->db_level != 0) {
list_destroy(&dr->dt.di.dr_children);
mutex_destroy(&dr->dt.di.dr_mtx);
}
kmem_free(dr, sizeof (dbuf_dirty_record_t));
ASSERT(db->db_dirtycnt > 0);
db->db_dirtycnt -= 1;
dbuf_rele_and_unlock(db, (void *)(uintptr_t)txg);
return;
}
os = dn->dn_objset;
/*
* 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 immediate 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 (db->db_state != DB_NOFILL &&
dn->dn_object != DMU_META_DNODE_OBJECT &&
refcount_count(&db->db_holds) > 1 &&
dr->dt.dl.dr_override_state != DR_OVERRIDDEN &&
*datap == db->db_buf) {
/*
* 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).
*/
int blksz = arc_buf_size(*datap);
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);
}
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);
DB_DNODE_EXIT(db);
} else {
/*
* Although zio_nowait() does not "wait for an IO", it does
* initiate the IO. If this is an empty write it seems plausible
* that the IO could actually be completed before the nowait
* returns. We need to DB_DNODE_EXIT() first in case
* zio_nowait() invalidates the dbuf.
*/
DB_DNODE_EXIT(db);
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);
}
}
/* ARGSUSED */
static void
dbuf_write_ready(zio_t *zio, arc_buf_t *buf, void *vdb)
{
dmu_buf_impl_t *db = vdb;
dnode_t *dn;
blkptr_t *bp = zio->io_bp;
blkptr_t *bp_orig = &zio->io_bp_orig;
spa_t *spa = zio->io_spa;
int64_t delta;
uint64_t fill = 0;
int i;
ASSERT(db->db_blkptr == bp);
DB_DNODE_ENTER(db);
dn = DB_DNODE(db);
delta = bp_get_dsize_sync(spa, bp) - bp_get_dsize_sync(spa, bp_orig);
dnode_diduse_space(dn, delta - zio->io_prev_space_delta);
zio->io_prev_space_delta = delta;
if (BP_IS_HOLE(bp)) {
ASSERT(bp->blk_fill == 0);
DB_DNODE_EXIT(db);
return;
}
ASSERT((db->db_blkid != DMU_SPILL_BLKID &&
BP_GET_TYPE(bp) == dn->dn_type) ||
(db->db_blkid == DMU_SPILL_BLKID &&
BP_GET_TYPE(bp) == dn->dn_bonustype));
ASSERT(BP_GET_LEVEL(bp) == db->db_level);
mutex_enter(&db->db_mtx);
#ifdef ZFS_DEBUG
if (db->db_blkid == DMU_SPILL_BLKID) {
ASSERT(dn->dn_phys->dn_flags & DNODE_FLAG_SPILL_BLKPTR);
ASSERT(!(BP_IS_HOLE(db->db_blkptr)) &&
db->db_blkptr == &dn->dn_phys->dn_spill);
}
#endif
if (db->db_level == 0) {
mutex_enter(&dn->dn_mtx);
if (db->db_blkid > dn->dn_phys->dn_maxblkid &&
db->db_blkid != DMU_SPILL_BLKID)
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;
fill += ibp->blk_fill;
}
}
DB_DNODE_EXIT(db);
bp->blk_fill = fill;
mutex_exit(&db->db_mtx);
}
/* ARGSUSED */
static void
dbuf_write_done(zio_t *zio, arc_buf_t *buf, void *vdb)
{
dmu_buf_impl_t *db = vdb;
blkptr_t *bp = zio->io_bp;
blkptr_t *bp_orig = &zio->io_bp_orig;
uint64_t txg = zio->io_txg;
dbuf_dirty_record_t **drp, *dr;
ASSERT3U(zio->io_error, ==, 0);
ASSERT(db->db_blkptr == bp);
if (zio->io_flags & ZIO_FLAG_IO_REWRITE) {
ASSERT(BP_EQUAL(bp, bp_orig));
} else {
objset_t *os;
dsl_dataset_t *ds;
dmu_tx_t *tx;
DB_GET_OBJSET(&os, db);
ds = os->os_dsl_dataset;
tx = os->os_synctx;
(void) dsl_dataset_block_kill(ds, bp_orig, tx, B_TRUE);
dsl_dataset_block_born(ds, bp, tx);
}
mutex_enter(&db->db_mtx);
DBUF_VERIFY(db);
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_dbuf == db);
ASSERT(dr->dr_next == NULL);
*drp = dr->dr_next;
#ifdef ZFS_DEBUG
if (db->db_blkid == DMU_SPILL_BLKID) {
dnode_t *dn;
DB_DNODE_ENTER(db);
dn = DB_DNODE(db);
ASSERT(dn->dn_phys->dn_flags & DNODE_FLAG_SPILL_BLKPTR);
ASSERT(!(BP_IS_HOLE(db->db_blkptr)) &&
db->db_blkptr == &dn->dn_phys->dn_spill);
DB_DNODE_EXIT(db);
}
#endif
if (db->db_level == 0) {
ASSERT(db->db_blkid != DMU_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 (!arc_released(db->db_buf))
arc_set_callback(db->db_buf, dbuf_do_evict, db);
}
} else {
dnode_t *dn;
DB_DNODE_ENTER(db);
dn = DB_DNODE(db);
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);
}
DB_DNODE_EXIT(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;
dbuf_rele_and_unlock(db, (void *)(uintptr_t)txg);
}
static void
dbuf_write_nofill_ready(zio_t *zio)
{
dbuf_write_ready(zio, NULL, zio->io_private);
}
static void
dbuf_write_nofill_done(zio_t *zio)
{
dbuf_write_done(zio, NULL, zio->io_private);
}
static void
dbuf_write_override_ready(zio_t *zio)
{
dbuf_dirty_record_t *dr = zio->io_private;
dmu_buf_impl_t *db = dr->dr_dbuf;
dbuf_write_ready(zio, NULL, db);
}
static void
dbuf_write_override_done(zio_t *zio)
{
dbuf_dirty_record_t *dr = zio->io_private;
dmu_buf_impl_t *db = dr->dr_dbuf;
blkptr_t *obp = &dr->dt.dl.dr_overridden_by;
mutex_enter(&db->db_mtx);
if (!BP_EQUAL(zio->io_bp, obp)) {
if (!BP_IS_HOLE(obp))
dsl_free(spa_get_dsl(zio->io_spa), zio->io_txg, obp);
arc_release(dr->dt.dl.dr_data, db);
}
mutex_exit(&db->db_mtx);
dbuf_write_done(zio, NULL, db);
}
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;
objset_t *os;
dmu_buf_impl_t *parent = db->db_parent;
uint64_t txg = tx->tx_txg;
zbookmark_t zb;
zio_prop_t zp;
zio_t *zio;
int wp_flag = 0;
DB_DNODE_ENTER(db);
dn = DB_DNODE(db);
os = dn->dn_objset;
if (db->db_state != DB_NOFILL) {
if (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.
*/
if (BP_IS_HOLE(db->db_blkptr)) {
arc_buf_thaw(data);
} else {
dbuf_release_bp(db);
}
}
}
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 &&
db->db_blkid != DMU_SPILL_BLKID) ||
(db->db_blkid == DMU_SPILL_BLKID && db->db_level == 0));
if (db->db_blkid != DMU_SPILL_BLKID)
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);
SET_BOOKMARK(&zb, os->os_dsl_dataset ?
os->os_dsl_dataset->ds_object : DMU_META_OBJSET,
db->db.db_object, db->db_level, db->db_blkid);
if (db->db_blkid == DMU_SPILL_BLKID)
wp_flag = WP_SPILL;
wp_flag |= (db->db_state == DB_NOFILL) ? WP_NOFILL : 0;
dmu_write_policy(os, dn, db->db_level, wp_flag, &zp);
DB_DNODE_EXIT(db);
if (db->db_level == 0 && dr->dt.dl.dr_override_state == DR_OVERRIDDEN) {
ASSERT(db->db_state != DB_NOFILL);
dr->dr_zio = zio_write(zio, os->os_spa, txg,
db->db_blkptr, data->b_data, arc_buf_size(data), &zp,
dbuf_write_override_ready, dbuf_write_override_done, dr,
ZIO_PRIORITY_ASYNC_WRITE, ZIO_FLAG_MUSTSUCCEED, &zb);
mutex_enter(&db->db_mtx);
dr->dt.dl.dr_override_state = DR_NOT_OVERRIDDEN;
zio_write_override(dr->dr_zio, &dr->dt.dl.dr_overridden_by,
dr->dt.dl.dr_copies);
mutex_exit(&db->db_mtx);
} else if (db->db_state == DB_NOFILL) {
ASSERT(zp.zp_checksum == ZIO_CHECKSUM_OFF);
dr->dr_zio = zio_write(zio, os->os_spa, txg,
db->db_blkptr, NULL, db->db.db_size, &zp,
dbuf_write_nofill_ready, dbuf_write_nofill_done, db,
ZIO_PRIORITY_ASYNC_WRITE,
ZIO_FLAG_MUSTSUCCEED | ZIO_FLAG_NODATA, &zb);
} else {
ASSERT(arc_released(data));
dr->dr_zio = arc_write(zio, os->os_spa, txg,
db->db_blkptr, data, DBUF_IS_L2CACHEABLE(db), &zp,
dbuf_write_ready, dbuf_write_done, db,
ZIO_PRIORITY_ASYNC_WRITE, ZIO_FLAG_MUSTSUCCEED, &zb);
}
}