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dbuf.c
3903 lines (3406 loc) · 110 KB
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dbuf.c
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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.
* Copyright (c) 2012, 2017 by Delphix. All rights reserved.
* Copyright (c) 2013 by Saso Kiselkov. All rights reserved.
* Copyright (c) 2014 Spectra Logic Corporation, All rights reserved.
*/
#include <sys/zfs_context.h>
#include <sys/arc.h>
#include <sys/dmu.h>
#include <sys/dmu_send.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>
#include <sys/zfeature.h>
#include <sys/blkptr.h>
#include <sys/range_tree.h>
#include <sys/trace_dbuf.h>
#include <sys/callb.h>
#include <sys/abd.h>
struct dbuf_hold_impl_data {
/* Function arguments */
dnode_t *dh_dn;
uint8_t dh_level;
uint64_t dh_blkid;
boolean_t dh_fail_sparse;
boolean_t dh_fail_uncached;
void *dh_tag;
dmu_buf_impl_t **dh_dbp;
/* Local variables */
dmu_buf_impl_t *dh_db;
dmu_buf_impl_t *dh_parent;
blkptr_t *dh_bp;
int dh_err;
dbuf_dirty_record_t *dh_dr;
int dh_depth;
};
static void __dbuf_hold_impl_init(struct dbuf_hold_impl_data *dh,
dnode_t *dn, uint8_t level, uint64_t blkid, boolean_t fail_sparse,
boolean_t fail_uncached,
void *tag, dmu_buf_impl_t **dbp, int depth);
static int __dbuf_hold_impl(struct dbuf_hold_impl_data *dh);
uint_t zfs_dbuf_evict_key;
static boolean_t 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);
extern inline void dmu_buf_init_user(dmu_buf_user_t *dbu,
dmu_buf_evict_func_t *evict_func_sync,
dmu_buf_evict_func_t *evict_func_async,
dmu_buf_t **clear_on_evict_dbufp);
/*
* Global data structures and functions for the dbuf cache.
*/
static kmem_cache_t *dbuf_kmem_cache;
static taskq_t *dbu_evict_taskq;
static kthread_t *dbuf_cache_evict_thread;
static kmutex_t dbuf_evict_lock;
static kcondvar_t dbuf_evict_cv;
static boolean_t dbuf_evict_thread_exit;
/*
* LRU cache of dbufs. The dbuf cache maintains a list of dbufs that
* are not currently held but have been recently released. These dbufs
* are not eligible for arc eviction until they are aged out of the cache.
* Dbufs are added to the dbuf cache once the last hold is released. If a
* dbuf is later accessed and still exists in the dbuf cache, then it will
* be removed from the cache and later re-added to the head of the cache.
* Dbufs that are aged out of the cache will be immediately destroyed and
* become eligible for arc eviction.
*/
static multilist_t *dbuf_cache;
static refcount_t dbuf_cache_size;
unsigned long dbuf_cache_max_bytes = 100 * 1024 * 1024;
/* Cap the size of the dbuf cache to log2 fraction of arc size. */
int dbuf_cache_max_shift = 5;
/*
* The dbuf cache uses a three-stage eviction policy:
* - A low water marker designates when the dbuf eviction thread
* should stop evicting from the dbuf cache.
* - When we reach the maximum size (aka mid water mark), we
* signal the eviction thread to run.
* - The high water mark indicates when the eviction thread
* is unable to keep up with the incoming load and eviction must
* happen in the context of the calling thread.
*
* The dbuf cache:
* (max size)
* low water mid water hi water
* +----------------------------------------+----------+----------+
* | | | |
* | | | |
* | | | |
* | | | |
* +----------------------------------------+----------+----------+
* stop signal evict
* evicting eviction directly
* thread
*
* The high and low water marks indicate the operating range for the eviction
* thread. The low water mark is, by default, 90% of the total size of the
* cache and the high water mark is at 110% (both of these percentages can be
* changed by setting dbuf_cache_lowater_pct and dbuf_cache_hiwater_pct,
* respectively). The eviction thread will try to ensure that the cache remains
* within this range by waking up every second and checking if the cache is
* above the low water mark. The thread can also be woken up by callers adding
* elements into the cache if the cache is larger than the mid water (i.e max
* cache size). Once the eviction thread is woken up and eviction is required,
* it will continue evicting buffers until it's able to reduce the cache size
* to the low water mark. If the cache size continues to grow and hits the high
* water mark, then callers adding elements to the cache will begin to evict
* directly from the cache until the cache is no longer above the high water
* mark.
*/
/*
* The percentage above and below the maximum cache size.
*/
uint_t dbuf_cache_hiwater_pct = 10;
uint_t dbuf_cache_lowater_pct = 10;
/* 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);
multilist_link_init(&db->db_cache_link);
refcount_create(&db->db_holds);
multilist_link_init(&db->db_cache_link);
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);
ASSERT(!multilist_link_active(&db->db_cache_link));
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_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(objset_t *os, uint64_t obj, uint8_t level, uint64_t blkid)
{
dbuf_hash_table_t *h = &dbuf_hash_table;
uint64_t hv;
uint64_t idx;
dmu_buf_impl_t *db;
hv = dbuf_hash(os, obj, level, blkid);
idx = hv & h->hash_table_mask;
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);
}
static dmu_buf_impl_t *
dbuf_find_bonus(objset_t *os, uint64_t object)
{
dnode_t *dn;
dmu_buf_impl_t *db = NULL;
if (dnode_hold(os, object, FTAG, &dn) == 0) {
rw_enter(&dn->dn_struct_rwlock, RW_READER);
if (dn->dn_bonus != NULL) {
db = dn->dn_bonus;
mutex_enter(&db->db_mtx);
}
rw_exit(&dn->dn_struct_rwlock);
dnode_rele(dn, FTAG);
}
return (db);
}
/*
* 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, hv, idx;
dmu_buf_impl_t *dbf;
blkid = db->db_blkid;
hv = dbuf_hash(os, obj, level, blkid);
idx = hv & h->hash_table_mask;
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_inc_64(&dbuf_hash_count);
return (NULL);
}
/*
* Remove an entry from the hash table. It must be in the EVICTING state.
*/
static void
dbuf_hash_remove(dmu_buf_impl_t *db)
{
dbuf_hash_table_t *h = &dbuf_hash_table;
uint64_t hv, idx;
dmu_buf_impl_t *dbf, **dbp;
hv = dbuf_hash(db->db_objset, db->db.db_object,
db->db_level, db->db_blkid);
idx = hv & h->hash_table_mask;
/*
* We mustn't hold db_mtx to maintain 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_dec_64(&dbuf_hash_count);
}
typedef enum {
DBVU_EVICTING,
DBVU_NOT_EVICTING
} dbvu_verify_type_t;
static void
dbuf_verify_user(dmu_buf_impl_t *db, dbvu_verify_type_t verify_type)
{
#ifdef ZFS_DEBUG
int64_t holds;
if (db->db_user == NULL)
return;
/* Only data blocks support the attachment of user data. */
ASSERT(db->db_level == 0);
/* Clients must resolve a dbuf before attaching user data. */
ASSERT(db->db.db_data != NULL);
ASSERT3U(db->db_state, ==, DB_CACHED);
holds = refcount_count(&db->db_holds);
if (verify_type == DBVU_EVICTING) {
/*
* Immediate eviction occurs when holds == dirtycnt.
* For normal eviction buffers, holds is zero on
* eviction, except when dbuf_fix_old_data() calls
* dbuf_clear_data(). However, the hold count can grow
* during eviction even though db_mtx is held (see
* dmu_bonus_hold() for an example), so we can only
* test the generic invariant that holds >= dirtycnt.
*/
ASSERT3U(holds, >=, db->db_dirtycnt);
} else {
if (db->db_user_immediate_evict == TRUE)
ASSERT3U(holds, >=, db->db_dirtycnt);
else
ASSERT3U(holds, >, 0);
}
#endif
}
static void
dbuf_evict_user(dmu_buf_impl_t *db)
{
dmu_buf_user_t *dbu = db->db_user;
ASSERT(MUTEX_HELD(&db->db_mtx));
if (dbu == NULL)
return;
dbuf_verify_user(db, DBVU_EVICTING);
db->db_user = NULL;
#ifdef ZFS_DEBUG
if (dbu->dbu_clear_on_evict_dbufp != NULL)
*dbu->dbu_clear_on_evict_dbufp = NULL;
#endif
/*
* There are two eviction callbacks - one that we call synchronously
* and one that we invoke via a taskq. The async one is useful for
* avoiding lock order reversals and limiting stack depth.
*
* Note that if we have a sync callback but no async callback,
* it's likely that the sync callback will free the structure
* containing the dbu. In that case we need to take care to not
* dereference dbu after calling the sync evict func.
*/
boolean_t has_async = (dbu->dbu_evict_func_async != NULL);
if (dbu->dbu_evict_func_sync != NULL)
dbu->dbu_evict_func_sync(dbu);
if (has_async) {
taskq_dispatch_ent(dbu_evict_taskq, dbu->dbu_evict_func_async,
dbu, 0, &dbu->dbu_tqent);
}
}
boolean_t
dbuf_is_metadata(dmu_buf_impl_t *db)
{
/*
* Consider indirect blocks and spill blocks to be meta data.
*/
if (db->db_level > 0 || db->db_blkid == DMU_SPILL_BLKID) {
return (B_TRUE);
} else {
boolean_t is_metadata;
DB_DNODE_ENTER(db);
is_metadata = DMU_OT_IS_METADATA(DB_DNODE(db)->dn_type);
DB_DNODE_EXIT(db);
return (is_metadata);
}
}
/*
* This function *must* return indices evenly distributed between all
* sublists of the multilist. This is needed due to how the dbuf eviction
* code is laid out; dbuf_evict_thread() assumes dbufs are evenly
* distributed between all sublists and uses this assumption when
* deciding which sublist to evict from and how much to evict from it.
*/
unsigned int
dbuf_cache_multilist_index_func(multilist_t *ml, void *obj)
{
dmu_buf_impl_t *db = obj;
/*
* The assumption here, is the hash value for a given
* dmu_buf_impl_t will remain constant throughout it's lifetime
* (i.e. it's objset, object, level and blkid fields don't change).
* Thus, we don't need to store the dbuf's sublist index
* on insertion, as this index can be recalculated on removal.
*
* Also, the low order bits of the hash value are thought to be
* distributed evenly. Otherwise, in the case that the multilist
* has a power of two number of sublists, each sublists' usage
* would not be evenly distributed.
*/
return (dbuf_hash(db->db_objset, db->db.db_object,
db->db_level, db->db_blkid) %
multilist_get_num_sublists(ml));
}
static inline unsigned long
dbuf_cache_target_bytes(void)
{
return MIN(dbuf_cache_max_bytes,
arc_target_bytes() >> dbuf_cache_max_shift);
}
static inline boolean_t
dbuf_cache_above_hiwater(void)
{
uint64_t dbuf_cache_target = dbuf_cache_target_bytes();
uint64_t dbuf_cache_hiwater_bytes =
(dbuf_cache_target * dbuf_cache_hiwater_pct) / 100;
return (refcount_count(&dbuf_cache_size) >
dbuf_cache_target + dbuf_cache_hiwater_bytes);
}
static inline boolean_t
dbuf_cache_above_lowater(void)
{
uint64_t dbuf_cache_target = dbuf_cache_target_bytes();
uint64_t dbuf_cache_lowater_bytes =
(dbuf_cache_target * dbuf_cache_lowater_pct) / 100;
return (refcount_count(&dbuf_cache_size) >
dbuf_cache_target - dbuf_cache_lowater_bytes);
}
/*
* Evict the oldest eligible dbuf from the dbuf cache.
*/
static void
dbuf_evict_one(void)
{
int idx = multilist_get_random_index(dbuf_cache);
multilist_sublist_t *mls = multilist_sublist_lock(dbuf_cache, idx);
dmu_buf_impl_t *db;
ASSERT(!MUTEX_HELD(&dbuf_evict_lock));
/*
* Set the thread's tsd to indicate that it's processing evictions.
* Once a thread stops evicting from the dbuf cache it will
* reset its tsd to NULL.
*/
ASSERT3P(tsd_get(zfs_dbuf_evict_key), ==, NULL);
(void) tsd_set(zfs_dbuf_evict_key, (void *)B_TRUE);
db = multilist_sublist_tail(mls);
while (db != NULL && mutex_tryenter(&db->db_mtx) == 0) {
db = multilist_sublist_prev(mls, db);
}
DTRACE_PROBE2(dbuf__evict__one, dmu_buf_impl_t *, db,
multilist_sublist_t *, mls);
if (db != NULL) {
multilist_sublist_remove(mls, db);
multilist_sublist_unlock(mls);
(void) refcount_remove_many(&dbuf_cache_size,
db->db.db_size, db);
dbuf_destroy(db);
} else {
multilist_sublist_unlock(mls);
}
(void) tsd_set(zfs_dbuf_evict_key, NULL);
}
/*
* The dbuf evict thread is responsible for aging out dbufs from the
* cache. Once the cache has reached it's maximum size, dbufs are removed
* and destroyed. The eviction thread will continue running until the size
* of the dbuf cache is at or below the maximum size. Once the dbuf is aged
* out of the cache it is destroyed and becomes eligible for arc eviction.
*/
static void
dbuf_evict_thread(void)
{
callb_cpr_t cpr;
CALLB_CPR_INIT(&cpr, &dbuf_evict_lock, callb_generic_cpr, FTAG);
mutex_enter(&dbuf_evict_lock);
while (!dbuf_evict_thread_exit) {
while (!dbuf_cache_above_lowater() && !dbuf_evict_thread_exit) {
CALLB_CPR_SAFE_BEGIN(&cpr);
(void) cv_timedwait_sig_hires(&dbuf_evict_cv,
&dbuf_evict_lock, SEC2NSEC(1), MSEC2NSEC(1), 0);
CALLB_CPR_SAFE_END(&cpr, &dbuf_evict_lock);
}
mutex_exit(&dbuf_evict_lock);
/*
* Keep evicting as long as we're above the low water mark
* for the cache. We do this without holding the locks to
* minimize lock contention.
*/
while (dbuf_cache_above_lowater() && !dbuf_evict_thread_exit) {
dbuf_evict_one();
}
mutex_enter(&dbuf_evict_lock);
}
dbuf_evict_thread_exit = B_FALSE;
cv_broadcast(&dbuf_evict_cv);
CALLB_CPR_EXIT(&cpr); /* drops dbuf_evict_lock */
thread_exit();
}
/*
* Wake up the dbuf eviction thread if the dbuf cache is at its max size.
* If the dbuf cache is at its high water mark, then evict a dbuf from the
* dbuf cache using the callers context.
*/
static void
dbuf_evict_notify(void)
{
/*
* We use thread specific data to track when a thread has
* started processing evictions. This allows us to avoid deeply
* nested stacks that would have a call flow similar to this:
*
* dbuf_rele()-->dbuf_rele_and_unlock()-->dbuf_evict_notify()
* ^ |
* | |
* +-----dbuf_destroy()<--dbuf_evict_one()<--------+
*
* The dbuf_eviction_thread will always have its tsd set until
* that thread exits. All other threads will only set their tsd
* if they are participating in the eviction process. This only
* happens if the eviction thread is unable to process evictions
* fast enough. To keep the dbuf cache size in check, other threads
* can evict from the dbuf cache directly. Those threads will set
* their tsd values so that we ensure that they only evict one dbuf
* from the dbuf cache.
*/
if (tsd_get(zfs_dbuf_evict_key) != NULL)
return;
/*
* We check if we should evict without holding the dbuf_evict_lock,
* because it's OK to occasionally make the wrong decision here,
* and grabbing the lock results in massive lock contention.
*/
if (refcount_count(&dbuf_cache_size) > dbuf_cache_target_bytes()) {
if (dbuf_cache_above_hiwater())
dbuf_evict_one();
cv_signal(&dbuf_evict_cv);
}
}
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 block size of zfs_arc_average_blocksize (default 8K).
* By default, the table will take up
* totalmem * sizeof(void*) / 8K (1MB per GB with 8-byte pointers).
*/
while (hsize * zfs_arc_average_blocksize < physmem * PAGESIZE)
hsize <<= 1;
retry:
h->hash_table_mask = hsize - 1;
#if defined(_KERNEL) && defined(HAVE_SPL)
/*
* Large allocations which do not require contiguous pages
* should be using vmem_alloc() in the linux kernel
*/
h->hash_table = vmem_zalloc(hsize * sizeof (void *), KM_SLEEP);
#else
h->hash_table = kmem_zalloc(hsize * sizeof (void *), KM_NOSLEEP);
#endif
if (h->hash_table == NULL) {
/* XXX - we should really return an error instead of assert */
ASSERT(hsize > (1ULL << 10));
hsize >>= 1;
goto retry;
}
dbuf_kmem_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);
dbuf_stats_init(h);
/*
* Setup the parameters for the dbuf cache. We cap the size of the
* dbuf cache to 1/32nd (default) of the size of the ARC.
*/
dbuf_cache_max_bytes = MIN(dbuf_cache_max_bytes,
arc_target_bytes() >> dbuf_cache_max_shift);
/*
* All entries are queued via taskq_dispatch_ent(), so min/maxalloc
* configuration is not required.
*/
dbu_evict_taskq = taskq_create("dbu_evict", 1, defclsyspri, 0, 0, 0);
dbuf_cache = multilist_create(sizeof (dmu_buf_impl_t),
offsetof(dmu_buf_impl_t, db_cache_link),
dbuf_cache_multilist_index_func);
refcount_create(&dbuf_cache_size);
tsd_create(&zfs_dbuf_evict_key, NULL);
dbuf_evict_thread_exit = B_FALSE;
mutex_init(&dbuf_evict_lock, NULL, MUTEX_DEFAULT, NULL);
cv_init(&dbuf_evict_cv, NULL, CV_DEFAULT, NULL);
dbuf_cache_evict_thread = thread_create(NULL, 0, dbuf_evict_thread,
NULL, 0, &p0, TS_RUN, minclsyspri);
}
void
dbuf_fini(void)
{
dbuf_hash_table_t *h = &dbuf_hash_table;
int i;
dbuf_stats_destroy();
for (i = 0; i < DBUF_MUTEXES; i++)
mutex_destroy(&h->hash_mutexes[i]);
#if defined(_KERNEL) && defined(HAVE_SPL)
/*
* Large allocations which do not require contiguous pages
* should be using vmem_free() in the linux kernel
*/
vmem_free(h->hash_table, (h->hash_table_mask + 1) * sizeof (void *));
#else
kmem_free(h->hash_table, (h->hash_table_mask + 1) * sizeof (void *));
#endif
kmem_cache_destroy(dbuf_kmem_cache);
taskq_destroy(dbu_evict_taskq);
mutex_enter(&dbuf_evict_lock);
dbuf_evict_thread_exit = B_TRUE;
while (dbuf_evict_thread_exit) {
cv_signal(&dbuf_evict_cv);
cv_wait(&dbuf_evict_cv, &dbuf_evict_lock);
}
mutex_exit(&dbuf_evict_lock);
tsd_destroy(&zfs_dbuf_evict_key);
mutex_destroy(&dbuf_evict_lock);
cv_destroy(&dbuf_evict_cv);
refcount_destroy(&dbuf_cache_size);
multilist_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 ||
!avl_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);
ASSERT0(db->db.db_offset);
} 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 */
ASSERTV(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.
*
* There is an exception to this rule for indirect blocks; in
* this case, if the indirect block is a hole, we fill in a few
* fields on each of the child blocks (importantly, birth time)
* to prevent hole birth times from being lost when you
* partially fill in a hole.
*/
if (db->db_dirtycnt == 0) {
if (db->db_level == 0) {
uint64_t *buf = db->db.db_data;
int i;
for (i = 0; i < db->db.db_size >> 3; i++) {
ASSERT(buf[i] == 0);
}
} else {
int i;
blkptr_t *bps = db->db.db_data;
ASSERT3U(1 << DB_DNODE(db)->dn_indblkshift, ==,
db->db.db_size);
/*
* We want to verify that all the blkptrs in the
* indirect block are holes, but we may have
* automatically set up a few fields for them.
* We iterate through each blkptr and verify
* they only have those fields set.
*/
for (i = 0;
i < db->db.db_size / sizeof (blkptr_t);
i++) {
blkptr_t *bp = &bps[i];
ASSERT(ZIO_CHECKSUM_IS_ZERO(
&bp->blk_cksum));
ASSERT(
DVA_IS_EMPTY(&bp->blk_dva[0]) &&
DVA_IS_EMPTY(&bp->blk_dva[1]) &&
DVA_IS_EMPTY(&bp->blk_dva[2]));
ASSERT0(bp->blk_fill);
ASSERT0(bp->blk_pad[0]);
ASSERT0(bp->blk_pad[1]);
ASSERT(!BP_IS_EMBEDDED(bp));
ASSERT(BP_IS_HOLE(bp));
ASSERT0(bp->blk_phys_birth);
}
}
}
}
DB_DNODE_EXIT(db);
}
#endif
static void
dbuf_clear_data(dmu_buf_impl_t *db)
{
ASSERT(MUTEX_HELD(&db->db_mtx));
dbuf_evict_user(db);
ASSERT3P(db->db_buf, ==, NULL);
db->db.db_data = NULL;
if (db->db_state != DB_NOFILL)
db->db_state = DB_UNCACHED;
}
static void
dbuf_set_data(dmu_buf_impl_t *db, arc_buf_t *buf)
{
ASSERT(MUTEX_HELD(&db->db_mtx));
ASSERT(buf != NULL);
db->db_buf = buf;
ASSERT(buf->b_data != NULL);
db->db.db_data = buf->b_data;
}
/*
* 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;
ASSERT(db->db_blkid != DMU_BONUS_BLKID);
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 = db->db_objset->os_spa;
mutex_exit(&db->db_mtx);
abuf = arc_loan_buf(spa, B_FALSE, blksz);
bcopy(db->db.db_data, abuf->b_data, blksz);
} else {
abuf = db->db_buf;
arc_loan_inuse_buf(abuf, db);
db->db_buf = NULL;
dbuf_clear_data(db);
mutex_exit(&db->db_mtx);
}
return (abuf);
}
/*
* Calculate which level n block references the data at the level 0 offset
* provided.
*/
uint64_t
dbuf_whichblock(const dnode_t *dn, const int64_t level, const uint64_t offset)
{
if (dn->dn_datablkshift != 0 && dn->dn_indblkshift != 0) {
/*
* The level n blkid is equal to the level 0 blkid divided by
* the number of level 0s in a level n block.
*
* The level 0 blkid is offset >> datablkshift =
* offset / 2^datablkshift.
*
* The number of level 0s in a level n is the number of block
* pointers in an indirect block, raised to the power of level.
* This is 2^(indblkshift - SPA_BLKPTRSHIFT)^level =
* 2^(level*(indblkshift - SPA_BLKPTRSHIFT)).
*
* Thus, the level n blkid is: offset /
* ((2^datablkshift)*(2^(level*(indblkshift - SPA_BLKPTRSHIFT)))
* = offset / 2^(datablkshift + level *
* (indblkshift - SPA_BLKPTRSHIFT))
* = offset >> (datablkshift + level *
* (indblkshift - SPA_BLKPTRSHIFT))
*/
const unsigned exp = dn->dn_datablkshift +
level * (dn->dn_indblkshift - SPA_BLKPTRSHIFT);
if (exp >= 8 * sizeof (offset)) {
/* This only happens on the highest indirection level */
ASSERT3U(level, ==, dn->dn_nlevels - 1);
return (0);
}
ASSERT3U(exp, <, 8 * sizeof (offset));
return (offset >> exp);
} 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 {