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freebsd-nq/module/zfs/dbuf.c
Matthew Ahrens 38240ebd7a OpenZFS 8156 - dbuf_evict_notify() does not need dbuf_evict_lock 
Authored by: Matthew Ahrens <mahrens@delphix.com>
Reviewed by: Dan Kimmel <dan.kimmel@delphix.com>
Reviewed by: Paul Dagnelie <pcd@delphix.com>
Approved by: Robert Mustacchi <rm@joyent.com>
Reviewed-by: George Melikov <mail@gmelikov.ru>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Ported-by: Giuseppe Di Natale <dinatale2@llnl.gov>

dbuf_evict_notify() holds the dbuf_evict_lock while checking if it should
do the eviction itself (because the evict thread is not able to keep up).
This can result in massive lock contention.  It isn't necessary to hold
the lock, because if we make the wrong choice occasionally, nothing bad
will happen. This commit results in a ~60% performance improvement for
ARC-cached sequential reads.

OpenZFS-issue: https://www.illumos.org/issues/8156
OpenZFS-commit: https://github.com/openzfs/openzfs/commit/f73e5d9
Closes #6204
2017-06-09 09:45:13 -07:00

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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;
arc_buf_contents_t dh_type;
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 boolean_t
dbuf_cache_above_hiwater(void)
{
uint64_t dbuf_cache_hiwater_bytes =
(dbuf_cache_max_bytes * dbuf_cache_hiwater_pct) / 100;
return (refcount_count(&dbuf_cache_size) >
dbuf_cache_max_bytes + dbuf_cache_hiwater_bytes);
}
static inline boolean_t
dbuf_cache_above_lowater(void)
{
uint64_t dbuf_cache_lowater_bytes =
(dbuf_cache_max_bytes * dbuf_cache_lowater_pct) / 100;
return (refcount_count(&dbuf_cache_size) >
dbuf_cache_max_bytes - 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_max_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_max_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 {
ASSERT(db->db_blkid != DMU_BONUS_BLKID);
ASSERT3P(db->db_buf, ==, NULL);
arc_buf_destroy(buf, db);
db->db_state = DB_UNCACHED;
}
cv_broadcast(&db->db_changed);
dbuf_rele_and_unlock(db, NULL);
}
static int
dbuf_read_impl(dmu_buf_impl_t *db, zio_t *zio, uint32_t flags)
{
dnode_t *dn;
zbookmark_phys_t zb;
uint32_t aflags = ARC_FLAG_NOWAIT;
int err;
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) {
/*
* The bonus length stored in the dnode may be less than
* the maximum available space in the bonus buffer.
*/
int bonuslen = MIN(dn->dn_bonuslen, dn->dn_phys->dn_bonuslen);
int max_bonuslen = DN_SLOTS_TO_BONUSLEN(dn->dn_num_slots);
ASSERT3U(bonuslen, <=, db->db.db_size);
db->db.db_data = kmem_alloc(max_bonuslen, KM_SLEEP);
arc_space_consume(max_bonuslen, ARC_SPACE_BONUS);
if (bonuslen < max_bonuslen)
bzero(db->db.db_data, max_bonuslen);
if (bonuslen)
bcopy(DN_BONUS(dn->dn_phys), db->db.db_data, bonuslen);
DB_DNODE_EXIT(db);
db->db_state = DB_CACHED;
mutex_exit(&db->db_mtx);
return (0);
}
/*
* 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_alloc_buf(db->db_objset->os_spa, db, type,
db->db.db_size));
bzero(db->db.db_data, db->db.db_size);
if (db->db_blkptr != NULL && db->db_level > 0 &&
BP_IS_HOLE(db->db_blkptr) &&
db->db_blkptr->blk_birth != 0) {
blkptr_t *bps = db->db.db_data;
int i;
for (i = 0; i < ((1 <<
DB_DNODE(db)->dn_indblkshift) / sizeof (blkptr_t));
i++) {
blkptr_t *bp = &bps[i];
ASSERT3U(BP_GET_LSIZE(db->db_blkptr), ==,
1 << dn->dn_indblkshift);
BP_SET_LSIZE(bp,
BP_GET_LEVEL(db->db_blkptr) == 1 ?
dn->dn_datablksz :
BP_GET_LSIZE(db->db_blkptr));
BP_SET_TYPE(bp, BP_GET_TYPE(db->db_blkptr));
BP_SET_LEVEL(bp,
BP_GET_LEVEL(db->db_blkptr) - 1);
BP_SET_BIRTH(bp, db->db_blkptr->blk_birth, 0);
}
}
DB_DNODE_EXIT(db);
db->db_state = DB_CACHED;
mutex_exit(&db->db_mtx);
return (0);
}
DB_DNODE_EXIT(db);
db->db_state = DB_READ;
mutex_exit(&db->db_mtx);
if (DBUF_IS_L2CACHEABLE(db))
aflags |= ARC_FLAG_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);
err = arc_read(zio, db->db_objset->os_spa, db->db_blkptr,
dbuf_read_done, db, ZIO_PRIORITY_SYNC_READ,
(flags & DB_RF_CANFAIL) ? ZIO_FLAG_CANFAIL : ZIO_FLAG_MUSTSUCCEED,
&aflags, &zb);
return (err);
}
/*
* 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 access them in
* the current active group.
*
* This function is used in three places: when we are dirtying a buffer for the
* first time in a txg, when we are freeing a range in a dnode that includes
* this buffer, and when we are accessing a buffer which was received compressed
* and later referenced in a WRITE_BYREF record.
*
* 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) {
dnode_t *dn = DB_DNODE(db);
int bonuslen = DN_SLOTS_TO_BONUSLEN(dn->dn_num_slots);
dr->dt.dl.dr_data = kmem_alloc(bonuslen, KM_SLEEP);
arc_space_consume(bonuslen, ARC_SPACE_BONUS);
bcopy(db->db.db_data, dr->dt.dl.dr_data, bonuslen);
} else if (refcount_count(&db->db_holds) > db->db_dirtycnt) {
int size = arc_buf_size(db->db_buf);
arc_buf_contents_t type = DBUF_GET_BUFC_TYPE(db);
spa_t *spa = db->db_objset->os_spa;
enum zio_compress compress_type =
arc_get_compression(db->db_buf);
if (compress_type == ZIO_COMPRESS_OFF) {
dr->dt.dl.dr_data = arc_alloc_buf(spa, db, type, size);
} else {
ASSERT3U(type, ==, ARC_BUFC_DATA);
dr->dt.dl.dr_data = arc_alloc_compressed_buf(spa, db,
size, arc_buf_lsize(db->db_buf), compress_type);
}
bcopy(db->db.db_data, dr->dt.dl.dr_data->b_data, size);
} else {
db->db_buf = NULL;
dbuf_clear_data(db);
}
}
int
dbuf_read(dmu_buf_impl_t *db, zio_t *zio, uint32_t flags)
{
int err = 0;
boolean_t 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 (SET_ERROR(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) {
/*
* If the arc buf is compressed, we need to decompress it to
* read the data. This could happen during the "zfs receive" of
* a stream which is compressed and deduplicated.
*/
if (db->db_buf != NULL &&
arc_get_compression(db->db_buf) != ZIO_COMPRESS_OFF) {
dbuf_fix_old_data(db,
spa_syncing_txg(dmu_objset_spa(db->db_objset)));
err = arc_decompress(db->db_buf);
dbuf_set_data(db, db->db_buf);
}
mutex_exit(&db->db_mtx);
if (prefetch)
dmu_zfetch(&dn->dn_zfetch, db->db_blkid, 1, B_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;
boolean_t need_wait = B_FALSE;
if (zio == NULL &&
db->db_blkptr != NULL && !BP_IS_HOLE(db->db_blkptr)) {
zio = zio_root(spa, NULL, NULL, ZIO_FLAG_CANFAIL);
need_wait = B_TRUE;
}
err = dbuf_read_impl(db, zio, flags);
/* dbuf_read_impl has dropped db_mtx for us */
if (!err && prefetch)
dmu_zfetch(&dn->dn_zfetch, db->db_blkid, 1, B_TRUE);
if ((flags & DB_RF_HAVESTRUCT) == 0)
rw_exit(&dn->dn_struct_rwlock);
DB_DNODE_EXIT(db);
if (!err && need_wait)
err = zio_wait(zio);
} else {
/*
* Another reader came in while the dbuf was in flight
* between UNCACHED and CACHED. Either a writer will finish
* writing the buffer (sending the dbuf to CACHED) or the
* first reader's request will reach the read_done callback
* and send the dbuf to CACHED. Otherwise, a failure
* occurred and the dbuf went to UNCACHED.
*/
mutex_exit(&db->db_mtx);
if (prefetch)
dmu_zfetch(&dn->dn_zfetch, db->db_blkid, 1, B_TRUE);
if ((flags & DB_RF_HAVESTRUCT) == 0)
rw_exit(&dn->dn_struct_rwlock);
DB_DNODE_EXIT(db);
/* Skip the wait per the caller's request. */
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);
DTRACE_PROBE2(blocked__read, dmu_buf_impl_t *,
db, zio_t *, zio);
cv_wait(&db->db_changed, &db->db_mtx);
}
if (db->db_state == DB_UNCACHED)
err = SET_ERROR(EIO);
}
mutex_exit(&db->db_mtx);
}
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 = db->db_objset->os_spa;
ASSERT(db->db_buf == NULL);
ASSERT(db->db.db_data == NULL);
dbuf_set_data(db, arc_alloc_buf(spa, db, type, db->db.db_size));
db->db_state = DB_FILL;
} else if (db->db_state == DB_NOFILL) {
dbuf_clear_data(db);
} else {
ASSERT3U(db->db_state, ==, DB_CACHED);
}
mutex_exit(&db->db_mtx);
}
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));
/*
* This assert is valid because dmu_sync() expects to be called by
* a zilog's get_data while holding a range lock. This call only
* comes from dbuf_dirty() callers who must also hold a range lock.
*/
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) && !dr->dt.dl.dr_nopwrite)
zio_free(db->db_objset->os_spa, txg, bp);
dr->dt.dl.dr_override_state = DR_NOT_OVERRIDDEN;
dr->dt.dl.dr_nopwrite = B_FALSE;
/*
* 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.
*/
void
dbuf_free_range(dnode_t *dn, uint64_t start_blkid, uint64_t end_blkid,
dmu_tx_t *tx)
{
dmu_buf_impl_t *db_search;
dmu_buf_impl_t *db, *db_next;
uint64_t txg = tx->tx_txg;
avl_index_t where;
if (end_blkid > dn->dn_maxblkid &&
!(start_blkid == DMU_SPILL_BLKID || end_blkid == DMU_SPILL_BLKID))
end_blkid = dn->dn_maxblkid;
dprintf_dnode(dn, "start=%llu end=%llu\n", start_blkid, end_blkid);
db_search = kmem_alloc(sizeof (dmu_buf_impl_t), KM_SLEEP);
db_search->db_level = 0;
db_search->db_blkid = start_blkid;
db_search->db_state = DB_SEARCH;
mutex_enter(&dn->dn_dbufs_mtx);
db = avl_find(&dn->dn_dbufs, db_search, &where);
ASSERT3P(db, ==, NULL);
db = avl_nearest(&dn->dn_dbufs, where, AVL_AFTER);
for (; db != NULL; db = db_next) {
db_next = AVL_NEXT(&dn->dn_dbufs, db);
ASSERT(db->db_blkid != DMU_BONUS_BLKID);
if (db->db_level != 0 || db->db_blkid > end_blkid) {
break;
}
ASSERT3U(db->db_blkid, >=, start_blkid);
/* found a level 0 buffer in the range */
mutex_enter(&db->db_mtx);
if (dbuf_undirty(db, tx)) {
/* mutex has been dropped and dbuf destroyed */
continue;
}
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_destroy(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);
}
kmem_free(db_search, sizeof (dmu_buf_impl_t));
mutex_exit(&dn->dn_dbufs_mtx);
}
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 dmu_buf_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
*/
dmu_buf_will_dirty(&db->db, tx);
/* create the data buffer for the new block */
buf = arc_alloc_buf(dn->dn_objset->os_spa, db, type, size);
/* 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);
arc_buf_destroy(obuf, db);
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);
dmu_objset_willuse_space(dn->dn_objset, size - osize, tx);
DB_DNODE_EXIT(db);
}
void
dbuf_release_bp(dmu_buf_impl_t *db)
{
ASSERTV(objset_t *os = db->db_objset);
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));
(void) arc_release(db->db_buf, db);
}
/*
* We already have a dirty record for this TXG, and we are being
* dirtied again.
*/
static void
dbuf_redirty(dbuf_dirty_record_t *dr)
{
dmu_buf_impl_t *db = dr->dr_dbuf;
ASSERT(MUTEX_HELD(&db->db_mtx));
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) {
/* Already released on initial dirty, so just thaw. */
ASSERT(arc_released(db->db_buf));
arc_buf_thaw(db->db_buf);
}
}
}
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;
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.
*/
#ifdef DEBUG
if (dn->dn_objset->os_dsl_dataset != NULL) {
rrw_enter(&dn->dn_objset->os_dsl_dataset->ds_bp_rwlock,
RW_READER, FTAG);
}
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);
if (dn->dn_objset->os_dsl_dataset != NULL)
rrw_exit(&dn->dn_objset->os_dsl_dataset->ds_bp_rwlock, FTAG);
#endif
/*
* 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) {
if (dn->dn_objset->os_dsl_dataset != NULL) {
rrw_enter(&dn->dn_objset->os_dsl_dataset->ds_bp_rwlock,
RW_READER, FTAG);
}
if (!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);
}
if (dn->dn_objset->os_dsl_dataset != NULL) {
rrw_exit(&dn->dn_objset->os_dsl_dataset->ds_bp_rwlock,
FTAG);
}
}
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);
dbuf_redirty(dr);
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;
VERIFY3U(tx->tx_txg, <=, spa_final_dirty_txg(os->os_spa));
#ifdef DEBUG
if (dn->dn_objset->os_dsl_dataset != NULL)
rrw_enter(&os->os_dsl_dataset->ds_bp_rwlock, RW_READER, FTAG);
ASSERT(!dmu_tx_is_syncing(tx) || DMU_OBJECT_IS_SPECIAL(dn->dn_object) ||
os->os_dsl_dataset == NULL || BP_IS_HOLE(os->os_rootbp));
if (dn->dn_objset->os_dsl_dataset != NULL)
rrw_exit(&os->os_dsl_dataset->ds_bp_rwlock, FTAG);
#endif
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) {
dmu_objset_willuse_space(os, db->db.db_size, tx);
}
/*
* 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);
list_link_init(&dr->dr_dirty_node);
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_NOLOCKDEP, NULL);
list_create(&dr->dt.di.dr_children,
sizeof (dbuf_dirty_record_t),
offsetof(dbuf_dirty_record_t, dr_dirty_node));
}
if (db->db_blkid != DMU_BONUS_BLKID && os->os_dsl_dataset != NULL)
dr->dr_accounted = db->db.db_size;
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);
if (dn->dn_free_ranges[txgoff] != NULL) {
range_tree_clear(dn->dn_free_ranges[txgoff],
db->db_blkid, 1);
}
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);
}
/*
* The dn_struct_rwlock prevents db_blkptr from changing
* due to a write from syncing context completing
* while we are running, so we want to acquire it before
* looking at db_blkptr.
*/
if (!RW_WRITE_HELD(&dn->dn_struct_rwlock)) {
rw_enter(&dn->dn_struct_rwlock, RW_READER);
drop_struct_lock = TRUE;
}
/*
* If we are overwriting a dedup BP, then unless it is snapshotted,
* when we get to syncing context we will need to decrement its
* refcount in the DDT. Prefetch the relevant DDT block so that
* syncing context won't have to wait for the i/o.
*/
ddt_prefetch(os->os_spa, db->db_blkptr);
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);
/*
* Since we've dropped the mutex, it's possible that
* dbuf_undirty() might have changed this out from under us.
*/
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);
}
/*
* Undirty a buffer in the transaction group referenced by the given
* transaction. Return whether this evicted the dbuf.
*/
static boolean_t
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);
/*
* Due to our use of dn_nlevels below, this can only be called
* in open context, unless we are operating on the MOS.
* From syncing context, dn_nlevels may be different from the
* dn_nlevels used when dbuf was dirtied.
*/
ASSERT(db->db_objset ==
dmu_objset_pool(db->db_objset)->dp_meta_objset ||
txg != spa_syncing_txg(dmu_objset_spa(db->db_objset)));
ASSERT(db->db_blkid != DMU_BONUS_BLKID);
ASSERT0(db->db_level);
ASSERT(MUTEX_HELD(&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)
return (B_FALSE);
ASSERT(dr->dr_txg == txg);
ASSERT(dr->dr_dbuf == db);
DB_DNODE_ENTER(db);
dn = DB_DNODE(db);
dprintf_dbuf(db, "size=%llx\n", (u_longlong_t)db->db.db_size);
ASSERT(db->db.db_size != 0);
dsl_pool_undirty_space(dmu_objset_pool(dn->dn_objset),
dr->dr_accounted, txg);
*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_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)
arc_buf_destroy(dr->dt.dl.dr_data, db);
}
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) {
ASSERT(db->db_state == DB_NOFILL || arc_released(db->db_buf));
dbuf_destroy(db);
return (B_TRUE);
}
return (B_FALSE);
}
void
dmu_buf_will_dirty(dmu_buf_t *db_fake, dmu_tx_t *tx)
{
dmu_buf_impl_t *db = (dmu_buf_impl_t *)db_fake;
int rf = DB_RF_MUST_SUCCEED | DB_RF_NOPREFETCH;
dbuf_dirty_record_t *dr;
ASSERT(tx->tx_txg != 0);
ASSERT(!refcount_is_zero(&db->db_holds));
/*
* Quick check for dirtyness. For already dirty blocks, this
* reduces runtime of this function by >90%, and overall performance
* by 50% for some workloads (e.g. file deletion with indirect blocks
* cached).
*/
mutex_enter(&db->db_mtx);
for (dr = db->db_last_dirty;
dr != NULL && dr->dr_txg >= tx->tx_txg; dr = dr->dr_next) {
/*
* It's possible that it is already dirty but not cached,
* because there are some calls to dbuf_dirty() that don't
* go through dmu_buf_will_dirty().
*/
if (dr->dr_txg == tx->tx_txg && db->db_state == DB_CACHED) {
/* This dbuf is already dirty and cached. */
dbuf_redirty(dr);
mutex_exit(&db->db_mtx);
return;
}
}
mutex_exit(&db->db_mtx);
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);
}
void
dmu_buf_write_embedded(dmu_buf_t *dbuf, void *data,
bp_embedded_type_t etype, enum zio_compress comp,
int uncompressed_size, int compressed_size, int byteorder,
dmu_tx_t *tx)
{
dmu_buf_impl_t *db = (dmu_buf_impl_t *)dbuf;
struct dirty_leaf *dl;
dmu_object_type_t type;
if (etype == BP_EMBEDDED_TYPE_DATA) {
ASSERT(spa_feature_is_active(dmu_objset_spa(db->db_objset),
SPA_FEATURE_EMBEDDED_DATA));
}
DB_DNODE_ENTER(db);
type = DB_DNODE(db)->dn_type;
DB_DNODE_EXIT(db);
ASSERT0(db->db_level);
ASSERT(db->db_blkid != DMU_BONUS_BLKID);
dmu_buf_will_not_fill(dbuf, tx);
ASSERT3U(db->db_last_dirty->dr_txg, ==, tx->tx_txg);
dl = &db->db_last_dirty->dt.dl;
encode_embedded_bp_compressed(&dl->dr_overridden_by,
data, comp, uncompressed_size, compressed_size);
BPE_SET_ETYPE(&dl->dr_overridden_by, etype);
BP_SET_TYPE(&dl->dr_overridden_by, type);
BP_SET_LEVEL(&dl->dr_overridden_by, 0);
BP_SET_BYTEORDER(&dl->dr_overridden_by, byteorder);
dl->dr_override_state = DR_OVERRIDDEN;
dl->dr_overridden_by.blk_birth = db->db_last_dirty->dr_txg;
}
/*
* 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);
ASSERT3U(dbuf_is_metadata(db), ==, arc_is_metadata(buf));
ASSERT(buf != NULL);
ASSERT(arc_buf_lsize(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);
arc_buf_destroy(buf, db);
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;
arc_buf_destroy(db->db_buf, db);
} else if (dr == NULL || dr->dt.dl.dr_data != db->db_buf) {
arc_release(db->db_buf, db);
arc_buf_destroy(db->db_buf, db);
}
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);
dmu_buf_fill_done(&db->db, tx);
}
void
dbuf_destroy(dmu_buf_impl_t *db)
{
dnode_t *dn;
dmu_buf_impl_t *parent = db->db_parent;
dmu_buf_impl_t *dndb;
ASSERT(MUTEX_HELD(&db->db_mtx));
ASSERT(refcount_is_zero(&db->db_holds));
if (db->db_buf != NULL) {
arc_buf_destroy(db->db_buf, db);
db->db_buf = NULL;
}
if (db->db_blkid == DMU_BONUS_BLKID) {
int slots = DB_DNODE(db)->dn_num_slots;
int bonuslen = DN_SLOTS_TO_BONUSLEN(slots);
ASSERT(db->db.db_data != NULL);
kmem_free(db->db.db_data, bonuslen);
arc_space_return(bonuslen, ARC_SPACE_BONUS);
db->db_state = DB_UNCACHED;
}
dbuf_clear_data(db);
if (multilist_link_active(&db->db_cache_link)) {
multilist_remove(dbuf_cache, db);
(void) refcount_remove_many(&dbuf_cache_size,
db->db.db_size, db);
}
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;
/*
* Now that db_state is DB_EVICTING, nobody else can find this via
* the hash table. We can now drop db_mtx, which allows us to
* acquire the dn_dbufs_mtx.
*/
mutex_exit(&db->db_mtx);
DB_DNODE_ENTER(db);
dn = DB_DNODE(db);
dndb = dn->dn_dbuf;
if (db->db_blkid != DMU_BONUS_BLKID) {
boolean_t needlock = !MUTEX_HELD(&dn->dn_dbufs_mtx);
if (needlock)
mutex_enter(&dn->dn_dbufs_mtx);
avl_remove(&dn->dn_dbufs, db);
atomic_dec_32(&dn->dn_dbufs_count);
membar_producer();
DB_DNODE_EXIT(db);
if (needlock)
mutex_exit(&dn->dn_dbufs_mtx);
/*
* 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;
dbuf_hash_remove(db);
} else {
DB_DNODE_EXIT(db);
}
ASSERT(refcount_is_zero(&db->db_holds));
db->db_parent = NULL;
ASSERT(db->db_buf == NULL);
ASSERT(db->db.db_data == NULL);
ASSERT(db->db_hash_next == NULL);
ASSERT(db->db_blkptr == NULL);
ASSERT(db->db_data_pending == NULL);
ASSERT(!multilist_link_active(&db->db_cache_link));
kmem_cache_free(dbuf_kmem_cache, db);
arc_space_return(sizeof (dmu_buf_impl_t), ARC_SPACE_DBUF);
/*
* 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);
}
/*
* Note: While bpp will always be updated if the function returns success,
* parentp will not be updated if the dnode does not have dn_dbuf filled in;
* this happens when the dnode is the meta-dnode, or a userused or groupused
* object.
*/
__attribute__((always_inline))
static inline int
dbuf_findbp(dnode_t *dn, int level, uint64_t blkid, int fail_sparse,
dmu_buf_impl_t **parentp, blkptr_t **bpp, struct dbuf_hold_impl_data *dh)
{
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_SPILL_BLKPTR(dn->dn_phys);
else
*bpp = NULL;
dbuf_add_ref(dn->dn_dbuf, NULL);
*parentp = dn->dn_dbuf;
mutex_exit(&dn->dn_mtx);
return (0);
}
nlevels =
(dn->dn_phys->dn_nlevels == 0) ? 1 : dn->dn_phys->dn_nlevels;
epbs = dn->dn_indblkshift - SPA_BLKPTRSHIFT;
ASSERT3U(level * epbs, <, 64);
ASSERT(RW_LOCK_HELD(&dn->dn_struct_rwlock));
/*
* This assertion shouldn't trip as long as the max indirect block size
* is less than 1M. The reason for this is that up to that point,
* the number of levels required to address an entire object with blocks
* of size SPA_MINBLOCKSIZE satisfies nlevels * epbs + 1 <= 64. In
* other words, if N * epbs + 1 > 64, then if (N-1) * epbs + 1 > 55
* (i.e. we can address the entire object), objects will all use at most
* N-1 levels and the assertion won't overflow. However, once epbs is
* 13, 4 * 13 + 1 = 53, but 5 * 13 + 1 = 66. Then, 4 levels will not be
* enough to address an entire object, so objects will have 5 levels,
* but then this assertion will overflow.
*
* All this is to say that if we ever increase DN_MAX_INDBLKSHIFT, we
* need to redo this logic to handle overflows.
*/
ASSERT(level >= nlevels ||
((nlevels - level - 1) * epbs) +
highbit64(dn->dn_phys->dn_nblkptr) <= 64);
if (level >= nlevels ||
blkid >= ((uint64_t)dn->dn_phys->dn_nblkptr <<
((nlevels - level - 1) * epbs)) ||
(fail_sparse &&
blkid > (dn->dn_phys->dn_maxblkid >> (level * epbs)))) {
/* the buffer has no parent yet */
return (SET_ERROR(ENOENT));
} else if (level < nlevels-1) {
/* this block is referenced from an indirect block */
int err;
if (dh == NULL) {
err = dbuf_hold_impl(dn, level+1,
blkid >> epbs, fail_sparse, FALSE, NULL, parentp);
} else {
__dbuf_hold_impl_init(dh + 1, dn, dh->dh_level + 1,
blkid >> epbs, fail_sparse, FALSE, NULL,
parentp, dh->dh_depth + 1);
err = __dbuf_hold_impl(dh + 1);
}
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));
if (blkid > (dn->dn_phys->dn_maxblkid >> (level * epbs)))
ASSERT(BP_IS_HOLE(*bpp));
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_kmem_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 = NULL;
db->db_user_immediate_evict = FALSE;
db->db_freed_in_flight = FALSE;
db->db_pending_evict = FALSE;
if (blkid == DMU_BONUS_BLKID) {
ASSERT3P(parent, ==, dn->dn_dbuf);
db->db.db_size = DN_SLOTS_TO_BONUSLEN(dn->dn_num_slots) -
(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_DBUF);
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_kmem_cache, db);
mutex_exit(&dn->dn_dbufs_mtx);
return (odb);
}
avl_add(&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_DBUF);
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);
atomic_inc_32(&dn->dn_dbufs_count);
dprintf_dbuf(db, "db=%p\n", db);
return (db);
}
typedef struct dbuf_prefetch_arg {
spa_t *dpa_spa; /* The spa to issue the prefetch in. */
zbookmark_phys_t dpa_zb; /* The target block to prefetch. */
int dpa_epbs; /* Entries (blkptr_t's) Per Block Shift. */
int dpa_curlevel; /* The current level that we're reading */
dnode_t *dpa_dnode; /* The dnode associated with the prefetch */
zio_priority_t dpa_prio; /* The priority I/Os should be issued at. */
zio_t *dpa_zio; /* The parent zio_t for all prefetches. */
arc_flags_t dpa_aflags; /* Flags to pass to the final prefetch. */
} dbuf_prefetch_arg_t;
/*
* Actually issue the prefetch read for the block given.
*/
static void
dbuf_issue_final_prefetch(dbuf_prefetch_arg_t *dpa, blkptr_t *bp)
{
arc_flags_t aflags;
if (BP_IS_HOLE(bp) || BP_IS_EMBEDDED(bp))
return;
aflags = dpa->dpa_aflags | ARC_FLAG_NOWAIT | ARC_FLAG_PREFETCH;
ASSERT3U(dpa->dpa_curlevel, ==, BP_GET_LEVEL(bp));
ASSERT3U(dpa->dpa_curlevel, ==, dpa->dpa_zb.zb_level);
ASSERT(dpa->dpa_zio != NULL);
(void) arc_read(dpa->dpa_zio, dpa->dpa_spa, bp, NULL, NULL,
dpa->dpa_prio, ZIO_FLAG_CANFAIL | ZIO_FLAG_SPECULATIVE,
&aflags, &dpa->dpa_zb);
}
/*
* Called when an indirect block above our prefetch target is read in. This
* will either read in the next indirect block down the tree or issue the actual
* prefetch if the next block down is our target.
*/
static void
dbuf_prefetch_indirect_done(zio_t *zio, arc_buf_t *abuf, void *private)
{
dbuf_prefetch_arg_t *dpa = private;
uint64_t nextblkid;
blkptr_t *bp;
ASSERT3S(dpa->dpa_zb.zb_level, <, dpa->dpa_curlevel);
ASSERT3S(dpa->dpa_curlevel, >, 0);
/*
* The dpa_dnode is only valid if we are called with a NULL
* zio. This indicates that the arc_read() returned without
* first calling zio_read() to issue a physical read. Once
* a physical read is made the dpa_dnode must be invalidated
* as the locks guarding it may have been dropped. If the
* dpa_dnode is still valid, then we want to add it to the dbuf
* cache. To do so, we must hold the dbuf associated with the block
* we just prefetched, read its contents so that we associate it
* with an arc_buf_t, and then release it.
*/
if (zio != NULL) {
ASSERT3S(BP_GET_LEVEL(zio->io_bp), ==, dpa->dpa_curlevel);
if (zio->io_flags & ZIO_FLAG_RAW) {
ASSERT3U(BP_GET_PSIZE(zio->io_bp), ==, zio->io_size);
} else {
ASSERT3U(BP_GET_LSIZE(zio->io_bp), ==, zio->io_size);
}
ASSERT3P(zio->io_spa, ==, dpa->dpa_spa);
dpa->dpa_dnode = NULL;
} else if (dpa->dpa_dnode != NULL) {
uint64_t curblkid = dpa->dpa_zb.zb_blkid >>
(dpa->dpa_epbs * (dpa->dpa_curlevel -
dpa->dpa_zb.zb_level));
dmu_buf_impl_t *db = dbuf_hold_level(dpa->dpa_dnode,
dpa->dpa_curlevel, curblkid, FTAG);
(void) dbuf_read(db, NULL,
DB_RF_MUST_SUCCEED | DB_RF_NOPREFETCH | DB_RF_HAVESTRUCT);
dbuf_rele(db, FTAG);
}
dpa->dpa_curlevel--;
nextblkid = dpa->dpa_zb.zb_blkid >>
(dpa->dpa_epbs * (dpa->dpa_curlevel - dpa->dpa_zb.zb_level));
bp = ((blkptr_t *)abuf->b_data) +
P2PHASE(nextblkid, 1ULL << dpa->dpa_epbs);
if (BP_IS_HOLE(bp) || (zio != NULL && zio->io_error != 0)) {
kmem_free(dpa, sizeof (*dpa));
} else if (dpa->dpa_curlevel == dpa->dpa_zb.zb_level) {
ASSERT3U(nextblkid, ==, dpa->dpa_zb.zb_blkid);
dbuf_issue_final_prefetch(dpa, bp);
kmem_free(dpa, sizeof (*dpa));
} else {
arc_flags_t iter_aflags = ARC_FLAG_NOWAIT;
zbookmark_phys_t zb;
ASSERT3U(dpa->dpa_curlevel, ==, BP_GET_LEVEL(bp));
SET_BOOKMARK(&zb, dpa->dpa_zb.zb_objset,
dpa->dpa_zb.zb_object, dpa->dpa_curlevel, nextblkid);
(void) arc_read(dpa->dpa_zio, dpa->dpa_spa,
bp, dbuf_prefetch_indirect_done, dpa, dpa->dpa_prio,
ZIO_FLAG_CANFAIL | ZIO_FLAG_SPECULATIVE,
&iter_aflags, &zb);
}
arc_buf_destroy(abuf, private);
}
/*
* Issue prefetch reads for the given block on the given level. If the indirect
* blocks above that block are not in memory, we will read them in
* asynchronously. As a result, this call never blocks waiting for a read to
* complete.
*/
void
dbuf_prefetch(dnode_t *dn, int64_t level, uint64_t blkid, zio_priority_t prio,
arc_flags_t aflags)
{
blkptr_t bp;
int epbs, nlevels, curlevel;
uint64_t curblkid;
dmu_buf_impl_t *db;
zio_t *pio;
dbuf_prefetch_arg_t *dpa;
dsl_dataset_t *ds;
ASSERT(blkid != DMU_BONUS_BLKID);
ASSERT(RW_LOCK_HELD(&dn->dn_struct_rwlock));
if (blkid > dn->dn_maxblkid)
return;
if (dnode_block_freed(dn, blkid))
return;
/*
* This dnode hasn't been written to disk yet, so there's nothing to
* prefetch.
*/
nlevels = dn->dn_phys->dn_nlevels;
if (level >= nlevels || dn->dn_phys->dn_nblkptr == 0)
return;
epbs = dn->dn_phys->dn_indblkshift - SPA_BLKPTRSHIFT;
if (dn->dn_phys->dn_maxblkid < blkid << (epbs * level))
return;
db = dbuf_find(dn->dn_objset, dn->dn_object,
level, blkid);
if (db != NULL) {
mutex_exit(&db->db_mtx);
/*
* This dbuf already exists. It is either CACHED, or
* (we assume) about to be read or filled.
*/
return;
}
/*
* Find the closest ancestor (indirect block) of the target block
* that is present in the cache. In this indirect block, we will
* find the bp that is at curlevel, curblkid.
*/
curlevel = level;
curblkid = blkid;
while (curlevel < nlevels - 1) {
int parent_level = curlevel + 1;
uint64_t parent_blkid = curblkid >> epbs;
dmu_buf_impl_t *db;
if (dbuf_hold_impl(dn, parent_level, parent_blkid,
FALSE, TRUE, FTAG, &db) == 0) {
blkptr_t *bpp = db->db_buf->b_data;
bp = bpp[P2PHASE(curblkid, 1 << epbs)];
dbuf_rele(db, FTAG);
break;
}
curlevel = parent_level;
curblkid = parent_blkid;
}
if (curlevel == nlevels - 1) {
/* No cached indirect blocks found. */
ASSERT3U(curblkid, <, dn->dn_phys->dn_nblkptr);
bp = dn->dn_phys->dn_blkptr[curblkid];
}
if (BP_IS_HOLE(&bp))
return;
ASSERT3U(curlevel, ==, BP_GET_LEVEL(&bp));
pio = zio_root(dmu_objset_spa(dn->dn_objset), NULL, NULL,
ZIO_FLAG_CANFAIL);
dpa = kmem_zalloc(sizeof (*dpa), KM_SLEEP);
ds = dn->dn_objset->os_dsl_dataset;
SET_BOOKMARK(&dpa->dpa_zb, ds != NULL ? ds->ds_object : DMU_META_OBJSET,
dn->dn_object, level, blkid);
dpa->dpa_curlevel = curlevel;
dpa->dpa_prio = prio;
dpa->dpa_aflags = aflags;
dpa->dpa_spa = dn->dn_objset->os_spa;
dpa->dpa_dnode = dn;
dpa->dpa_epbs = epbs;
dpa->dpa_zio = pio;
/*
* If we have the indirect just above us, no need to do the asynchronous
* prefetch chain; we'll just run the last step ourselves. If we're at
* a higher level, though, we want to issue the prefetches for all the
* indirect blocks asynchronously, so we can go on with whatever we were
* doing.
*/
if (curlevel == level) {
ASSERT3U(curblkid, ==, blkid);
dbuf_issue_final_prefetch(dpa, &bp);
kmem_free(dpa, sizeof (*dpa));
} else {
arc_flags_t iter_aflags = ARC_FLAG_NOWAIT;
zbookmark_phys_t zb;
SET_BOOKMARK(&zb, ds != NULL ? ds->ds_object : DMU_META_OBJSET,
dn->dn_object, curlevel, curblkid);
(void) arc_read(dpa->dpa_zio, dpa->dpa_spa,
&bp, dbuf_prefetch_indirect_done, dpa, prio,
ZIO_FLAG_CANFAIL | ZIO_FLAG_SPECULATIVE,
&iter_aflags, &zb);
}
/*
* We use pio here instead of dpa_zio since it's possible that
* dpa may have already been freed.
*/
zio_nowait(pio);
}
#define DBUF_HOLD_IMPL_MAX_DEPTH 20
/*
* Returns with db_holds incremented, and db_mtx not held.
* Note: dn_struct_rwlock must be held.
*/
static int
__dbuf_hold_impl(struct dbuf_hold_impl_data *dh)
{
ASSERT3S(dh->dh_depth, <, DBUF_HOLD_IMPL_MAX_DEPTH);
dh->dh_parent = NULL;
ASSERT(dh->dh_blkid != DMU_BONUS_BLKID);
ASSERT(RW_LOCK_HELD(&dh->dh_dn->dn_struct_rwlock));
ASSERT3U(dh->dh_dn->dn_nlevels, >, dh->dh_level);
*(dh->dh_dbp) = NULL;
/* dbuf_find() returns with db_mtx held */
dh->dh_db = dbuf_find(dh->dh_dn->dn_objset, dh->dh_dn->dn_object,
dh->dh_level, dh->dh_blkid);
if (dh->dh_db == NULL) {
dh->dh_bp = NULL;
if (dh->dh_fail_uncached)
return (SET_ERROR(ENOENT));
ASSERT3P(dh->dh_parent, ==, NULL);
dh->dh_err = dbuf_findbp(dh->dh_dn, dh->dh_level, dh->dh_blkid,
dh->dh_fail_sparse, &dh->dh_parent, &dh->dh_bp, dh);
if (dh->dh_fail_sparse) {
if (dh->dh_err == 0 &&
dh->dh_bp && BP_IS_HOLE(dh->dh_bp))
dh->dh_err = SET_ERROR(ENOENT);
if (dh->dh_err) {
if (dh->dh_parent)
dbuf_rele(dh->dh_parent, NULL);
return (dh->dh_err);
}
}
if (dh->dh_err && dh->dh_err != ENOENT)
return (dh->dh_err);
dh->dh_db = dbuf_create(dh->dh_dn, dh->dh_level, dh->dh_blkid,
dh->dh_parent, dh->dh_bp);
}
if (dh->dh_fail_uncached && dh->dh_db->db_state != DB_CACHED) {
mutex_exit(&dh->dh_db->db_mtx);
return (SET_ERROR(ENOENT));
}
if (dh->dh_db->db_buf != NULL)
ASSERT3P(dh->dh_db->db.db_data, ==, dh->dh_db->db_buf->b_data);
ASSERT(dh->dh_db->db_buf == NULL || arc_referenced(dh->dh_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 (dh->dh_db->db_level == 0 &&
dh->dh_db->db_blkid != DMU_BONUS_BLKID &&
dh->dh_dn->dn_object != DMU_META_DNODE_OBJECT &&
dh->dh_db->db_state == DB_CACHED && dh->dh_db->db_data_pending) {
dh->dh_dr = dh->dh_db->db_data_pending;
if (dh->dh_dr->dt.dl.dr_data == dh->dh_db->db_buf) {
dh->dh_type = DBUF_GET_BUFC_TYPE(dh->dh_db);
dbuf_set_data(dh->dh_db,
arc_alloc_buf(dh->dh_dn->dn_objset->os_spa,
dh->dh_db, dh->dh_type, dh->dh_db->db.db_size));
bcopy(dh->dh_dr->dt.dl.dr_data->b_data,
dh->dh_db->db.db_data, dh->dh_db->db.db_size);
}
}
if (multilist_link_active(&dh->dh_db->db_cache_link)) {
ASSERT(refcount_is_zero(&dh->dh_db->db_holds));
multilist_remove(dbuf_cache, dh->dh_db);
(void) refcount_remove_many(&dbuf_cache_size,
dh->dh_db->db.db_size, dh->dh_db);
}
(void) refcount_add(&dh->dh_db->db_holds, dh->dh_tag);
DBUF_VERIFY(dh->dh_db);
mutex_exit(&dh->dh_db->db_mtx);
/* NOTE: we can't rele the parent until after we drop the db_mtx */
if (dh->dh_parent)
dbuf_rele(dh->dh_parent, NULL);
ASSERT3P(DB_DNODE(dh->dh_db), ==, dh->dh_dn);
ASSERT3U(dh->dh_db->db_blkid, ==, dh->dh_blkid);
ASSERT3U(dh->dh_db->db_level, ==, dh->dh_level);
*(dh->dh_dbp) = dh->dh_db;
return (0);
}
/*
* The following code preserves the recursive function dbuf_hold_impl()
* but moves the local variables AND function arguments to the heap to
* minimize the stack frame size. Enough space is initially allocated
* on the stack for 20 levels of recursion.
*/
int
dbuf_hold_impl(dnode_t *dn, uint8_t level, uint64_t blkid,
boolean_t fail_sparse, boolean_t fail_uncached,
void *tag, dmu_buf_impl_t **dbp)
{
struct dbuf_hold_impl_data *dh;
int error;
dh = kmem_alloc(sizeof (struct dbuf_hold_impl_data) *
DBUF_HOLD_IMPL_MAX_DEPTH, KM_SLEEP);
__dbuf_hold_impl_init(dh, dn, level, blkid, fail_sparse,
fail_uncached, tag, dbp, 0);
error = __dbuf_hold_impl(dh);
kmem_free(dh, sizeof (struct dbuf_hold_impl_data) *
DBUF_HOLD_IMPL_MAX_DEPTH);
return (error);
}
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)
{
dh->dh_dn = dn;
dh->dh_level = level;
dh->dh_blkid = blkid;
dh->dh_fail_sparse = fail_sparse;
dh->dh_fail_uncached = fail_uncached;
dh->dh_tag = tag;
dh->dh_dbp = dbp;
dh->dh_db = NULL;
dh->dh_parent = NULL;
dh->dh_bp = NULL;
dh->dh_err = 0;
dh->dh_dr = NULL;
dh->dh_type = 0;
dh->dh_depth = depth;
}
dmu_buf_impl_t *
dbuf_hold(dnode_t *dn, uint64_t blkid, void *tag)
{
return (dbuf_hold_level(dn, 0, blkid, tag));
}
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, 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 (SET_ERROR(ENOTSUP));
if (blksz == 0)
blksz = SPA_MINBLOCKSIZE;
ASSERT3U(blksz, <=, spa_maxblocksize(dmu_objset_spa(db->db_objset)));
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);
VERIFY3S(holds, >, 1);
}
#pragma weak dmu_buf_try_add_ref = dbuf_try_add_ref
boolean_t
dbuf_try_add_ref(dmu_buf_t *db_fake, objset_t *os, uint64_t obj, uint64_t blkid,
void *tag)
{
dmu_buf_impl_t *db = (dmu_buf_impl_t *)db_fake;
dmu_buf_impl_t *found_db;
boolean_t result = B_FALSE;
if (blkid == DMU_BONUS_BLKID)
found_db = dbuf_find_bonus(os, obj);
else
found_db = dbuf_find(os, obj, 0, blkid);
if (found_db != NULL) {
if (db == found_db && dbuf_refcount(db) > db->db_dirtycnt) {
(void) refcount_add(&db->db_holds, tag);
result = B_TRUE;
}
mutex_exit(&found_db->db_mtx);
}
return (result);
}
/*
* 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.
*/
void
dbuf_rele(dmu_buf_impl_t *db, void *tag)
{
mutex_enter(&db->db_mtx);
dbuf_rele_and_unlock(db, tag);
}
void
dmu_buf_rele(dmu_buf_t *db, void *tag)
{
dbuf_rele((dmu_buf_impl_t *)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 != NULL &&
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_user_immediate_evict)
dbuf_evict_user(db);
if (holds == 0) {
if (db->db_blkid == DMU_BONUS_BLKID) {
dnode_t *dn;
boolean_t evict_dbuf = db->db_pending_evict;
/*
* If the dnode moves here, we cannot cross this
* barrier until the move completes.
*/
DB_DNODE_ENTER(db);
dn = DB_DNODE(db);
atomic_dec_32(&dn->dn_dbufs_count);
/*
* Decrementing the dbuf count means that the bonus
* buffer's dnode hold is no longer discounted in
* dnode_move(). The dnode cannot move until after
* the dnode_rele() below.
*/
DB_DNODE_EXIT(db);
/*
* Do not reference db after its lock is dropped.
* Another thread may evict it.
*/
mutex_exit(&db->db_mtx);
if (evict_dbuf)
dnode_evict_bonus(dn);
dnode_rele(dn, 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_destroy(db);
} else if (arc_released(db->db_buf)) {
/*
* This dbuf has anonymous data associated with it.
*/
dbuf_destroy(db);
} else {
boolean_t do_arc_evict = B_FALSE;
blkptr_t bp;
spa_t *spa = dmu_objset_spa(db->db_objset);
if (!DBUF_IS_CACHEABLE(db) &&
db->db_blkptr != NULL &&
!BP_IS_HOLE(db->db_blkptr) &&
!BP_IS_EMBEDDED(db->db_blkptr)) {
do_arc_evict = B_TRUE;
bp = *db->db_blkptr;
}
if (!DBUF_IS_CACHEABLE(db) ||
db->db_pending_evict) {
dbuf_destroy(db);
} else if (!multilist_link_active(&db->db_cache_link)) {
multilist_insert(dbuf_cache, db);
(void) refcount_add_many(&dbuf_cache_size,
db->db.db_size, db);
mutex_exit(&db->db_mtx);
dbuf_evict_notify();
}
if (do_arc_evict)
arc_freed(spa, &bp);
}
} 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_replace_user(dmu_buf_t *db_fake, dmu_buf_user_t *old_user,
dmu_buf_user_t *new_user)
{
dmu_buf_impl_t *db = (dmu_buf_impl_t *)db_fake;
mutex_enter(&db->db_mtx);
dbuf_verify_user(db, DBVU_NOT_EVICTING);
if (db->db_user == old_user)
db->db_user = new_user;
else
old_user = db->db_user;
dbuf_verify_user(db, DBVU_NOT_EVICTING);
mutex_exit(&db->db_mtx);
return (old_user);
}
void *
dmu_buf_set_user(dmu_buf_t *db_fake, dmu_buf_user_t *user)
{
return (dmu_buf_replace_user(db_fake, NULL, user));
}
void *
dmu_buf_set_user_ie(dmu_buf_t *db_fake, dmu_buf_user_t *user)
{
dmu_buf_impl_t *db = (dmu_buf_impl_t *)db_fake;
db->db_user_immediate_evict = TRUE;
return (dmu_buf_set_user(db_fake, user));
}
void *
dmu_buf_remove_user(dmu_buf_t *db_fake, dmu_buf_user_t *user)
{
return (dmu_buf_replace_user(db_fake, user, NULL));
}
void *
dmu_buf_get_user(dmu_buf_t *db_fake)
{
dmu_buf_impl_t *db = (dmu_buf_impl_t *)db_fake;
dbuf_verify_user(db, DBVU_NOT_EVICTING);
return (db->db_user);
}
void
dmu_buf_user_evict_wait()
{
taskq_wait(dbu_evict_taskq);
}
blkptr_t *
dmu_buf_get_blkptr(dmu_buf_t *db)
{
dmu_buf_impl_t *dbi = (dmu_buf_impl_t *)db;
return (dbi->db_blkptr);
}
objset_t *
dmu_buf_get_objset(dmu_buf_t *db)
{
dmu_buf_impl_t *dbi = (dmu_buf_impl_t *)db;
return (dbi->db_objset);
}
dnode_t *
dmu_buf_dnode_enter(dmu_buf_t *db)
{
dmu_buf_impl_t *dbi = (dmu_buf_impl_t *)db;
DB_DNODE_ENTER(dbi);
return (DB_DNODE(dbi));
}
void
dmu_buf_dnode_exit(dmu_buf_t *db)
{
dmu_buf_impl_t *dbi = (dmu_buf_impl_t *)db;
DB_DNODE_EXIT(dbi);
}
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_SPILL_BLKPTR(dn->dn_phys);
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);
parent = dbuf_hold_level(dn, db->db_level + 1,
db->db_blkid >> epbs, db);
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);
}
}
/*
* dbuf_sync_indirect() is called recursively from dbuf_sync_list() so it
* is critical the we not allow the compiler to inline this function in to
* dbuf_sync_list() thereby drastically bloating the stack usage.
*/
noinline 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);
/* Read the block if it hasn't been read yet. */
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);
/* Indirect block size must match what the dnode thinks it is. */
ASSERT3U(db->db.db_size, ==, 1<<dn->dn_phys->dn_indblkshift);
dbuf_check_blkptr(dn, db);
DB_DNODE_EXIT(db);
/* Provide the pending dirty record to child dbufs */
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, db->db_level - 1, tx);
ASSERT(list_head(&dr->dt.di.dr_children) == NULL);
mutex_exit(&dr->dt.di.dr_mtx);
zio_nowait(zio);
}
/*
* dbuf_sync_leaf() is called recursively from dbuf_sync_list() so it is
* critical the we not allow the compiler to inline this function in to
* dbuf_sync_list() thereby drastically bloating the stack usage.
*/
noinline 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);
if (!(dn->dn_phys->dn_flags & DNODE_FLAG_SPILL_BLKPTR)) {
/*
* In the previous transaction group, the bonus buffer
* was entirely used to store the attributes for the
* dnode which overrode the dn_spill field. However,
* when adding more attributes to the file a spill
* block was required to hold the extra attributes.
*
* Make sure to clear the garbage left in the dn_spill
* field from the previous attributes in the bonus
* buffer. Otherwise, after writing out the spill
* block to the new allocated dva, it will free
* the old block pointed to by the invalid dn_spill.
*/
db->db_blkptr = NULL;
}
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);
ASSERT0(db->db_level);
ASSERT3U(dn->dn_phys->dn_bonuslen, <=,
DN_SLOTS_TO_BONUSLEN(dn->dn_phys->dn_extra_slots + 1));
bcopy(*datap, DN_BONUS(dn->dn_phys), dn->dn_phys->dn_bonuslen);
DB_DNODE_EXIT(db);
if (*datap != db->db.db_data) {
int slots = DB_DNODE(db)->dn_num_slots;
int bonuslen = DN_SLOTS_TO_BONUSLEN(slots);
kmem_free(*datap, bonuslen);
arc_space_return(bonuslen, ARC_SPACE_BONUS);
}
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) {
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;
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 psize = arc_buf_size(*datap);
arc_buf_contents_t type = DBUF_GET_BUFC_TYPE(db);
enum zio_compress compress_type = arc_get_compression(*datap);
if (compress_type == ZIO_COMPRESS_OFF) {
*datap = arc_alloc_buf(os->os_spa, db, type, psize);
} else {
ASSERT3U(type, ==, ARC_BUFC_DATA);
int lsize = arc_buf_lsize(*datap);
*datap = arc_alloc_compressed_buf(os->os_spa, db,
psize, lsize, compress_type);
}
bcopy(db->db.db_data, (*datap)->b_data, psize);
}
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, int level, 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;
}
if (dr->dr_dbuf->db_blkid != DMU_BONUS_BLKID &&
dr->dr_dbuf->db_blkid != DMU_SPILL_BLKID) {
VERIFY3U(dr->dr_dbuf->db_level, ==, level);
}
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;
ASSERT3P(db->db_blkptr, !=, NULL);
ASSERT3P(&db->db_data_pending->dr_bp_copy, ==, 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->blk_birth != 0) {
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) ||
BP_IS_EMBEDDED(bp));
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(bp)) &&
db->db_blkptr == DN_SPILL_BLKPTR(dn->dn_phys));
}
#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) {
i = 0;
while (i < db->db.db_size) {
dnode_phys_t *dnp = db->db.db_data + i;
i += DNODE_MIN_SIZE;
if (dnp->dn_type != DMU_OT_NONE) {
fill++;
i += dnp->dn_extra_slots *
DNODE_MIN_SIZE;
}
}
} else {
if (BP_IS_HOLE(bp)) {
fill = 0;
} 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 += BP_GET_FILL(ibp);
}
}
DB_DNODE_EXIT(db);
if (!BP_IS_EMBEDDED(bp))
bp->blk_fill = fill;
mutex_exit(&db->db_mtx);
rw_enter(&dn->dn_struct_rwlock, RW_WRITER);
*db->db_blkptr = *bp;
rw_exit(&dn->dn_struct_rwlock);
}
/* ARGSUSED */
/*
* This function gets called just prior to running through the compression
* stage of the zio pipeline. If we're an indirect block comprised of only
* holes, then we want this indirect to be compressed away to a hole. In
* order to do that we must zero out any information about the holes that
* this indirect points to prior to before we try to compress it.
*/
static void
dbuf_write_children_ready(zio_t *zio, arc_buf_t *buf, void *vdb)
{
dmu_buf_impl_t *db = vdb;
dnode_t *dn;
blkptr_t *bp;
unsigned int epbs, i;
ASSERT3U(db->db_level, >, 0);
DB_DNODE_ENTER(db);
dn = DB_DNODE(db);
epbs = dn->dn_phys->dn_indblkshift - SPA_BLKPTRSHIFT;
ASSERT3U(epbs, <, 31);
/* Determine if all our children are holes */
for (i = 0, bp = db->db.db_data; i < 1ULL << epbs; i++, bp++) {
if (!BP_IS_HOLE(bp))
break;
}
/*
* If all the children are holes, then zero them all out so that
* we may get compressed away.
*/
if (i == 1ULL << epbs) {
/*
* We only found holes. Grab the rwlock to prevent
* anybody from reading the blocks we're about to
* zero out.
*/
rw_enter(&dn->dn_struct_rwlock, RW_WRITER);
bzero(db->db.db_data, db->db.db_size);
rw_exit(&dn->dn_struct_rwlock);
}
DB_DNODE_EXIT(db);
}
/*
* The SPA will call this callback several times for each zio - once
* for every physical child i/o (zio->io_phys_children times). This
* allows the DMU to monitor the progress of each logical i/o. For example,
* there may be 2 copies of an indirect block, or many fragments of a RAID-Z
* block. There may be a long delay before all copies/fragments are completed,
* so this callback allows us to retire dirty space gradually, as the physical
* i/os complete.
*/
/* ARGSUSED */
static void
dbuf_write_physdone(zio_t *zio, arc_buf_t *buf, void *arg)
{
dmu_buf_impl_t *db = arg;
objset_t *os = db->db_objset;
dsl_pool_t *dp = dmu_objset_pool(os);
dbuf_dirty_record_t *dr;
int delta = 0;
dr = db->db_data_pending;
ASSERT3U(dr->dr_txg, ==, zio->io_txg);
/*
* The callback will be called io_phys_children times. Retire one
* portion of our dirty space each time we are called. Any rounding
* error will be cleaned up by dsl_pool_sync()'s call to
* dsl_pool_undirty_space().
*/
delta = dr->dr_accounted / zio->io_phys_children;
dsl_pool_undirty_space(dp, delta, zio->io_txg);
}
/* ARGSUSED */
static void
dbuf_write_done(zio_t *zio, arc_buf_t *buf, void *vdb)
{
dmu_buf_impl_t *db = vdb;
blkptr_t *bp_orig = &zio->io_bp_orig;
blkptr_t *bp = db->db_blkptr;
objset_t *os = db->db_objset;
dmu_tx_t *tx = os->os_synctx;
dbuf_dirty_record_t **drp, *dr;
ASSERT0(zio->io_error);
ASSERT(db->db_blkptr == bp);
/*
* For nopwrites and rewrites we ensure that the bp matches our
* original and bypass all the accounting.
*/
if (zio->io_flags & (ZIO_FLAG_IO_REWRITE | ZIO_FLAG_NOPWRITE)) {
ASSERT(BP_EQUAL(bp, bp_orig));
} else {
dsl_dataset_t *ds = os->os_dsl_dataset;
(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_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_SPILL_BLKPTR(dn->dn_phys));
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)
arc_buf_destroy(dr->dt.dl.dr_data, 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)) {
ASSERTV(int epbs = dn->dn_phys->dn_indblkshift -
SPA_BLKPTRSHIFT);
ASSERT3U(db->db_blkid, <=,
dn->dn_phys->dn_maxblkid >> (db->db_level * epbs));
ASSERT3U(BP_GET_LSIZE(db->db_blkptr), ==,
db->db.db_size);
}
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)tx->tx_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);
if (zio->io_abd != NULL)
abd_put(zio->io_abd);
}
/* Issue I/O to commit a dirty buffer to disk. */
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_phys_t zb;
zio_prop_t zp;
zio_t *zio;
int wp_flag = 0;
ASSERT(dmu_tx_is_syncing(tx));
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) {
/* Our parent is an indirect block. */
/* We have a dirty parent that has been scheduled for write. */
ASSERT(parent && parent->db_data_pending);
/* Our parent's buffer is one level closer to the dnode. */
ASSERT(db->db_level == parent->db_level-1);
/*
* We're about to modify our parent's db_data by modifying
* our block pointer, so the parent must be released.
*/
ASSERT(arc_released(parent->db_buf));
zio = parent->db_data_pending->dr_zio;
} else {
/* Our parent is the dnode itself. */
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);
/*
* We copy the blkptr now (rather than when we instantiate the dirty
* record), because its value can change between open context and
* syncing context. We do not need to hold dn_struct_rwlock to read
* db_blkptr because we are in syncing context.
*/
dr->dr_bp_copy = *db->db_blkptr;
if (db->db_level == 0 &&
dr->dt.dl.dr_override_state == DR_OVERRIDDEN) {
/*
* The BP for this block has been provided by open context
* (by dmu_sync() or dmu_buf_write_embedded()).
*/
abd_t *contents = (data != NULL) ?
abd_get_from_buf(data->b_data, arc_buf_size(data)) : NULL;
dr->dr_zio = zio_write(zio, os->os_spa, txg,
&dr->dr_bp_copy, contents, db->db.db_size, db->db.db_size,
&zp, dbuf_write_override_ready, NULL, NULL,
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, dr->dt.dl.dr_nopwrite);
mutex_exit(&db->db_mtx);
} else if (db->db_state == DB_NOFILL) {
ASSERT(zp.zp_checksum == ZIO_CHECKSUM_OFF ||
zp.zp_checksum == ZIO_CHECKSUM_NOPARITY);
dr->dr_zio = zio_write(zio, os->os_spa, txg,
&dr->dr_bp_copy, NULL, db->db.db_size, db->db.db_size, &zp,
dbuf_write_nofill_ready, NULL, NULL,
dbuf_write_nofill_done, db,
ZIO_PRIORITY_ASYNC_WRITE,
ZIO_FLAG_MUSTSUCCEED | ZIO_FLAG_NODATA, &zb);
} else {
arc_done_func_t *children_ready_cb = NULL;
ASSERT(arc_released(data));
/*
* For indirect blocks, we want to setup the children
* ready callback so that we can properly handle an indirect
* block that only contains holes.
*/
if (db->db_level != 0)
children_ready_cb = dbuf_write_children_ready;
dr->dr_zio = arc_write(zio, os->os_spa, txg,
&dr->dr_bp_copy, data, DBUF_IS_L2CACHEABLE(db),
&zp, dbuf_write_ready,
children_ready_cb, dbuf_write_physdone,
dbuf_write_done, db, ZIO_PRIORITY_ASYNC_WRITE,
ZIO_FLAG_MUSTSUCCEED, &zb);
}
}
#if defined(_KERNEL) && defined(HAVE_SPL)
EXPORT_SYMBOL(dbuf_find);
EXPORT_SYMBOL(dbuf_is_metadata);
EXPORT_SYMBOL(dbuf_destroy);
EXPORT_SYMBOL(dbuf_loan_arcbuf);
EXPORT_SYMBOL(dbuf_whichblock);
EXPORT_SYMBOL(dbuf_read);
EXPORT_SYMBOL(dbuf_unoverride);
EXPORT_SYMBOL(dbuf_free_range);
EXPORT_SYMBOL(dbuf_new_size);
EXPORT_SYMBOL(dbuf_release_bp);
EXPORT_SYMBOL(dbuf_dirty);
EXPORT_SYMBOL(dmu_buf_will_dirty);
EXPORT_SYMBOL(dmu_buf_will_not_fill);
EXPORT_SYMBOL(dmu_buf_will_fill);
EXPORT_SYMBOL(dmu_buf_fill_done);
EXPORT_SYMBOL(dmu_buf_rele);
EXPORT_SYMBOL(dbuf_assign_arcbuf);
EXPORT_SYMBOL(dbuf_prefetch);
EXPORT_SYMBOL(dbuf_hold_impl);
EXPORT_SYMBOL(dbuf_hold);
EXPORT_SYMBOL(dbuf_hold_level);
EXPORT_SYMBOL(dbuf_create_bonus);
EXPORT_SYMBOL(dbuf_spill_set_blksz);
EXPORT_SYMBOL(dbuf_rm_spill);
EXPORT_SYMBOL(dbuf_add_ref);
EXPORT_SYMBOL(dbuf_rele);
EXPORT_SYMBOL(dbuf_rele_and_unlock);
EXPORT_SYMBOL(dbuf_refcount);
EXPORT_SYMBOL(dbuf_sync_list);
EXPORT_SYMBOL(dmu_buf_set_user);
EXPORT_SYMBOL(dmu_buf_set_user_ie);
EXPORT_SYMBOL(dmu_buf_get_user);
EXPORT_SYMBOL(dmu_buf_get_blkptr);
/* BEGIN CSTYLED */
module_param(dbuf_cache_max_bytes, ulong, 0644);
MODULE_PARM_DESC(dbuf_cache_max_bytes,
"Maximum size in bytes of the dbuf cache.");
module_param(dbuf_cache_hiwater_pct, uint, 0644);
MODULE_PARM_DESC(dbuf_cache_hiwater_pct,
"Percentage over dbuf_cache_max_bytes when dbufs must be evicted "
"directly.");
module_param(dbuf_cache_lowater_pct, uint, 0644);
MODULE_PARM_DESC(dbuf_cache_lowater_pct,
"Percentage below dbuf_cache_max_bytes when the evict thread stops "
"evicting dbufs.");
module_param(dbuf_cache_max_shift, int, 0644);
MODULE_PARM_DESC(dbuf_cache_max_shift,
"Cap the size of the dbuf cache to a log2 fraction of arc size.");
/* END CSTYLED */
#endif
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