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zfs-builds-mm/zfs-0.8.4/module/zfs/dsl_pool.c
root 1b460e5cea add_new_zfs
2020-07-19 16:21:53 +02:00

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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 (c) 2011, 2017 by Delphix. All rights reserved.
* Copyright (c) 2013 Steven Hartland. All rights reserved.
* Copyright (c) 2014 Spectra Logic Corporation, All rights reserved.
* Copyright 2016 Nexenta Systems, Inc. All rights reserved.
*/
#include <sys/dsl_pool.h>
#include <sys/dsl_dataset.h>
#include <sys/dsl_prop.h>
#include <sys/dsl_dir.h>
#include <sys/dsl_synctask.h>
#include <sys/dsl_scan.h>
#include <sys/dnode.h>
#include <sys/dmu_tx.h>
#include <sys/dmu_objset.h>
#include <sys/arc.h>
#include <sys/zap.h>
#include <sys/zio.h>
#include <sys/zfs_context.h>
#include <sys/fs/zfs.h>
#include <sys/zfs_znode.h>
#include <sys/spa_impl.h>
#include <sys/dsl_deadlist.h>
#include <sys/vdev_impl.h>
#include <sys/metaslab_impl.h>
#include <sys/bptree.h>
#include <sys/zfeature.h>
#include <sys/zil_impl.h>
#include <sys/dsl_userhold.h>
#include <sys/trace_txg.h>
#include <sys/mmp.h>
/*
* ZFS Write Throttle
* ------------------
*
* ZFS must limit the rate of incoming writes to the rate at which it is able
* to sync data modifications to the backend storage. Throttling by too much
* creates an artificial limit; throttling by too little can only be sustained
* for short periods and would lead to highly lumpy performance. On a per-pool
* basis, ZFS tracks the amount of modified (dirty) data. As operations change
* data, the amount of dirty data increases; as ZFS syncs out data, the amount
* of dirty data decreases. When the amount of dirty data exceeds a
* predetermined threshold further modifications are blocked until the amount
* of dirty data decreases (as data is synced out).
*
* The limit on dirty data is tunable, and should be adjusted according to
* both the IO capacity and available memory of the system. The larger the
* window, the more ZFS is able to aggregate and amortize metadata (and data)
* changes. However, memory is a limited resource, and allowing for more dirty
* data comes at the cost of keeping other useful data in memory (for example
* ZFS data cached by the ARC).
*
* Implementation
*
* As buffers are modified dsl_pool_willuse_space() increments both the per-
* txg (dp_dirty_pertxg[]) and poolwide (dp_dirty_total) accounting of
* dirty space used; dsl_pool_dirty_space() decrements those values as data
* is synced out from dsl_pool_sync(). While only the poolwide value is
* relevant, the per-txg value is useful for debugging. The tunable
* zfs_dirty_data_max determines the dirty space limit. Once that value is
* exceeded, new writes are halted until space frees up.
*
* The zfs_dirty_data_sync_percent tunable dictates the threshold at which we
* ensure that there is a txg syncing (see the comment in txg.c for a full
* description of transaction group stages).
*
* The IO scheduler uses both the dirty space limit and current amount of
* dirty data as inputs. Those values affect the number of concurrent IOs ZFS
* issues. See the comment in vdev_queue.c for details of the IO scheduler.
*
* The delay is also calculated based on the amount of dirty data. See the
* comment above dmu_tx_delay() for details.
*/
/*
* zfs_dirty_data_max will be set to zfs_dirty_data_max_percent% of all memory,
* capped at zfs_dirty_data_max_max. It can also be overridden with a module
* parameter.
*/
unsigned long zfs_dirty_data_max = 0;
unsigned long zfs_dirty_data_max_max = 0;
int zfs_dirty_data_max_percent = 10;
int zfs_dirty_data_max_max_percent = 25;
/*
* If there's at least this much dirty data (as a percentage of
* zfs_dirty_data_max), push out a txg. This should be less than
* zfs_vdev_async_write_active_min_dirty_percent.
*/
int zfs_dirty_data_sync_percent = 20;
/*
* Once there is this amount of dirty data, the dmu_tx_delay() will kick in
* and delay each transaction.
* This value should be >= zfs_vdev_async_write_active_max_dirty_percent.
*/
int zfs_delay_min_dirty_percent = 60;
/*
* This controls how quickly the delay approaches infinity.
* Larger values cause it to delay more for a given amount of dirty data.
* Therefore larger values will cause there to be less dirty data for a
* given throughput.
*
* For the smoothest delay, this value should be about 1 billion divided
* by the maximum number of operations per second. This will smoothly
* handle between 10x and 1/10th this number.
*
* Note: zfs_delay_scale * zfs_dirty_data_max must be < 2^64, due to the
* multiply in dmu_tx_delay().
*/
unsigned long zfs_delay_scale = 1000 * 1000 * 1000 / 2000;
/*
* This determines the number of threads used by the dp_sync_taskq.
*/
int zfs_sync_taskq_batch_pct = 75;
/*
* These tunables determine the behavior of how zil_itxg_clean() is
* called via zil_clean() in the context of spa_sync(). When an itxg
* list needs to be cleaned, TQ_NOSLEEP will be used when dispatching.
* If the dispatch fails, the call to zil_itxg_clean() will occur
* synchronously in the context of spa_sync(), which can negatively
* impact the performance of spa_sync() (e.g. in the case of the itxg
* list having a large number of itxs that needs to be cleaned).
*
* Thus, these tunables can be used to manipulate the behavior of the
* taskq used by zil_clean(); they determine the number of taskq entries
* that are pre-populated when the taskq is first created (via the
* "zfs_zil_clean_taskq_minalloc" tunable) and the maximum number of
* taskq entries that are cached after an on-demand allocation (via the
* "zfs_zil_clean_taskq_maxalloc").
*
* The idea being, we want to try reasonably hard to ensure there will
* already be a taskq entry pre-allocated by the time that it is needed
* by zil_clean(). This way, we can avoid the possibility of an
* on-demand allocation of a new taskq entry from failing, which would
* result in zil_itxg_clean() being called synchronously from zil_clean()
* (which can adversely affect performance of spa_sync()).
*
* Additionally, the number of threads used by the taskq can be
* configured via the "zfs_zil_clean_taskq_nthr_pct" tunable.
*/
int zfs_zil_clean_taskq_nthr_pct = 100;
int zfs_zil_clean_taskq_minalloc = 1024;
int zfs_zil_clean_taskq_maxalloc = 1024 * 1024;
int
dsl_pool_open_special_dir(dsl_pool_t *dp, const char *name, dsl_dir_t **ddp)
{
uint64_t obj;
int err;
err = zap_lookup(dp->dp_meta_objset,
dsl_dir_phys(dp->dp_root_dir)->dd_child_dir_zapobj,
name, sizeof (obj), 1, &obj);
if (err)
return (err);
return (dsl_dir_hold_obj(dp, obj, name, dp, ddp));
}
static dsl_pool_t *
dsl_pool_open_impl(spa_t *spa, uint64_t txg)
{
dsl_pool_t *dp;
blkptr_t *bp = spa_get_rootblkptr(spa);
dp = kmem_zalloc(sizeof (dsl_pool_t), KM_SLEEP);
dp->dp_spa = spa;
dp->dp_meta_rootbp = *bp;
rrw_init(&dp->dp_config_rwlock, B_TRUE);
txg_init(dp, txg);
mmp_init(spa);
txg_list_create(&dp->dp_dirty_datasets, spa,
offsetof(dsl_dataset_t, ds_dirty_link));
txg_list_create(&dp->dp_dirty_zilogs, spa,
offsetof(zilog_t, zl_dirty_link));
txg_list_create(&dp->dp_dirty_dirs, spa,
offsetof(dsl_dir_t, dd_dirty_link));
txg_list_create(&dp->dp_sync_tasks, spa,
offsetof(dsl_sync_task_t, dst_node));
txg_list_create(&dp->dp_early_sync_tasks, spa,
offsetof(dsl_sync_task_t, dst_node));
dp->dp_sync_taskq = taskq_create("dp_sync_taskq",
zfs_sync_taskq_batch_pct, minclsyspri, 1, INT_MAX,
TASKQ_THREADS_CPU_PCT);
dp->dp_zil_clean_taskq = taskq_create("dp_zil_clean_taskq",
zfs_zil_clean_taskq_nthr_pct, minclsyspri,
zfs_zil_clean_taskq_minalloc,
zfs_zil_clean_taskq_maxalloc,
TASKQ_PREPOPULATE | TASKQ_THREADS_CPU_PCT);
mutex_init(&dp->dp_lock, NULL, MUTEX_DEFAULT, NULL);
cv_init(&dp->dp_spaceavail_cv, NULL, CV_DEFAULT, NULL);
dp->dp_iput_taskq = taskq_create("z_iput", max_ncpus, defclsyspri,
max_ncpus * 8, INT_MAX, TASKQ_PREPOPULATE | TASKQ_DYNAMIC);
dp->dp_unlinked_drain_taskq = taskq_create("z_unlinked_drain",
max_ncpus, defclsyspri, max_ncpus, INT_MAX,
TASKQ_PREPOPULATE | TASKQ_DYNAMIC);
return (dp);
}
int
dsl_pool_init(spa_t *spa, uint64_t txg, dsl_pool_t **dpp)
{
int err;
dsl_pool_t *dp = dsl_pool_open_impl(spa, txg);
/*
* Initialize the caller's dsl_pool_t structure before we actually open
* the meta objset. This is done because a self-healing write zio may
* be issued as part of dmu_objset_open_impl() and the spa needs its
* dsl_pool_t initialized in order to handle the write.
*/
*dpp = dp;
err = dmu_objset_open_impl(spa, NULL, &dp->dp_meta_rootbp,
&dp->dp_meta_objset);
if (err != 0) {
dsl_pool_close(dp);
*dpp = NULL;
}
return (err);
}
int
dsl_pool_open(dsl_pool_t *dp)
{
int err;
dsl_dir_t *dd;
dsl_dataset_t *ds;
uint64_t obj;
rrw_enter(&dp->dp_config_rwlock, RW_WRITER, FTAG);
err = zap_lookup(dp->dp_meta_objset, DMU_POOL_DIRECTORY_OBJECT,
DMU_POOL_ROOT_DATASET, sizeof (uint64_t), 1,
&dp->dp_root_dir_obj);
if (err)
goto out;
err = dsl_dir_hold_obj(dp, dp->dp_root_dir_obj,
NULL, dp, &dp->dp_root_dir);
if (err)
goto out;
err = dsl_pool_open_special_dir(dp, MOS_DIR_NAME, &dp->dp_mos_dir);
if (err)
goto out;
if (spa_version(dp->dp_spa) >= SPA_VERSION_ORIGIN) {
err = dsl_pool_open_special_dir(dp, ORIGIN_DIR_NAME, &dd);
if (err)
goto out;
err = dsl_dataset_hold_obj(dp,
dsl_dir_phys(dd)->dd_head_dataset_obj, FTAG, &ds);
if (err == 0) {
err = dsl_dataset_hold_obj(dp,
dsl_dataset_phys(ds)->ds_prev_snap_obj, dp,
&dp->dp_origin_snap);
dsl_dataset_rele(ds, FTAG);
}
dsl_dir_rele(dd, dp);
if (err)
goto out;
}
if (spa_version(dp->dp_spa) >= SPA_VERSION_DEADLISTS) {
err = dsl_pool_open_special_dir(dp, FREE_DIR_NAME,
&dp->dp_free_dir);
if (err)
goto out;
err = zap_lookup(dp->dp_meta_objset, DMU_POOL_DIRECTORY_OBJECT,
DMU_POOL_FREE_BPOBJ, sizeof (uint64_t), 1, &obj);
if (err)
goto out;
VERIFY0(bpobj_open(&dp->dp_free_bpobj,
dp->dp_meta_objset, obj));
}
if (spa_feature_is_active(dp->dp_spa, SPA_FEATURE_OBSOLETE_COUNTS)) {
err = zap_lookup(dp->dp_meta_objset, DMU_POOL_DIRECTORY_OBJECT,
DMU_POOL_OBSOLETE_BPOBJ, sizeof (uint64_t), 1, &obj);
if (err == 0) {
VERIFY0(bpobj_open(&dp->dp_obsolete_bpobj,
dp->dp_meta_objset, obj));
} else if (err == ENOENT) {
/*
* We might not have created the remap bpobj yet.
*/
err = 0;
} else {
goto out;
}
}
/*
* Note: errors ignored, because the these special dirs, used for
* space accounting, are only created on demand.
*/
(void) dsl_pool_open_special_dir(dp, LEAK_DIR_NAME,
&dp->dp_leak_dir);
if (spa_feature_is_active(dp->dp_spa, SPA_FEATURE_ASYNC_DESTROY)) {
err = zap_lookup(dp->dp_meta_objset, DMU_POOL_DIRECTORY_OBJECT,
DMU_POOL_BPTREE_OBJ, sizeof (uint64_t), 1,
&dp->dp_bptree_obj);
if (err != 0)
goto out;
}
if (spa_feature_is_active(dp->dp_spa, SPA_FEATURE_EMPTY_BPOBJ)) {
err = zap_lookup(dp->dp_meta_objset, DMU_POOL_DIRECTORY_OBJECT,
DMU_POOL_EMPTY_BPOBJ, sizeof (uint64_t), 1,
&dp->dp_empty_bpobj);
if (err != 0)
goto out;
}
err = zap_lookup(dp->dp_meta_objset, DMU_POOL_DIRECTORY_OBJECT,
DMU_POOL_TMP_USERREFS, sizeof (uint64_t), 1,
&dp->dp_tmp_userrefs_obj);
if (err == ENOENT)
err = 0;
if (err)
goto out;
err = dsl_scan_init(dp, dp->dp_tx.tx_open_txg);
out:
rrw_exit(&dp->dp_config_rwlock, FTAG);
return (err);
}
void
dsl_pool_close(dsl_pool_t *dp)
{
/*
* Drop our references from dsl_pool_open().
*
* Since we held the origin_snap from "syncing" context (which
* includes pool-opening context), it actually only got a "ref"
* and not a hold, so just drop that here.
*/
if (dp->dp_origin_snap != NULL)
dsl_dataset_rele(dp->dp_origin_snap, dp);
if (dp->dp_mos_dir != NULL)
dsl_dir_rele(dp->dp_mos_dir, dp);
if (dp->dp_free_dir != NULL)
dsl_dir_rele(dp->dp_free_dir, dp);
if (dp->dp_leak_dir != NULL)
dsl_dir_rele(dp->dp_leak_dir, dp);
if (dp->dp_root_dir != NULL)
dsl_dir_rele(dp->dp_root_dir, dp);
bpobj_close(&dp->dp_free_bpobj);
bpobj_close(&dp->dp_obsolete_bpobj);
/* undo the dmu_objset_open_impl(mos) from dsl_pool_open() */
if (dp->dp_meta_objset != NULL)
dmu_objset_evict(dp->dp_meta_objset);
txg_list_destroy(&dp->dp_dirty_datasets);
txg_list_destroy(&dp->dp_dirty_zilogs);
txg_list_destroy(&dp->dp_sync_tasks);
txg_list_destroy(&dp->dp_early_sync_tasks);
txg_list_destroy(&dp->dp_dirty_dirs);
taskq_destroy(dp->dp_zil_clean_taskq);
taskq_destroy(dp->dp_sync_taskq);
/*
* We can't set retry to TRUE since we're explicitly specifying
* a spa to flush. This is good enough; any missed buffers for
* this spa won't cause trouble, and they'll eventually fall
* out of the ARC just like any other unused buffer.
*/
arc_flush(dp->dp_spa, FALSE);
mmp_fini(dp->dp_spa);
txg_fini(dp);
dsl_scan_fini(dp);
dmu_buf_user_evict_wait();
rrw_destroy(&dp->dp_config_rwlock);
mutex_destroy(&dp->dp_lock);
cv_destroy(&dp->dp_spaceavail_cv);
taskq_destroy(dp->dp_unlinked_drain_taskq);
taskq_destroy(dp->dp_iput_taskq);
if (dp->dp_blkstats != NULL) {
mutex_destroy(&dp->dp_blkstats->zab_lock);
vmem_free(dp->dp_blkstats, sizeof (zfs_all_blkstats_t));
}
kmem_free(dp, sizeof (dsl_pool_t));
}
void
dsl_pool_create_obsolete_bpobj(dsl_pool_t *dp, dmu_tx_t *tx)
{
uint64_t obj;
/*
* Currently, we only create the obsolete_bpobj where there are
* indirect vdevs with referenced mappings.
*/
ASSERT(spa_feature_is_active(dp->dp_spa, SPA_FEATURE_DEVICE_REMOVAL));
/* create and open the obsolete_bpobj */
obj = bpobj_alloc(dp->dp_meta_objset, SPA_OLD_MAXBLOCKSIZE, tx);
VERIFY0(bpobj_open(&dp->dp_obsolete_bpobj, dp->dp_meta_objset, obj));
VERIFY0(zap_add(dp->dp_meta_objset, DMU_POOL_DIRECTORY_OBJECT,
DMU_POOL_OBSOLETE_BPOBJ, sizeof (uint64_t), 1, &obj, tx));
spa_feature_incr(dp->dp_spa, SPA_FEATURE_OBSOLETE_COUNTS, tx);
}
void
dsl_pool_destroy_obsolete_bpobj(dsl_pool_t *dp, dmu_tx_t *tx)
{
spa_feature_decr(dp->dp_spa, SPA_FEATURE_OBSOLETE_COUNTS, tx);
VERIFY0(zap_remove(dp->dp_meta_objset,
DMU_POOL_DIRECTORY_OBJECT,
DMU_POOL_OBSOLETE_BPOBJ, tx));
bpobj_free(dp->dp_meta_objset,
dp->dp_obsolete_bpobj.bpo_object, tx);
bpobj_close(&dp->dp_obsolete_bpobj);
}
dsl_pool_t *
dsl_pool_create(spa_t *spa, nvlist_t *zplprops, dsl_crypto_params_t *dcp,
uint64_t txg)
{
int err;
dsl_pool_t *dp = dsl_pool_open_impl(spa, txg);
dmu_tx_t *tx = dmu_tx_create_assigned(dp, txg);
#ifdef _KERNEL
objset_t *os;
#else
objset_t *os __attribute__((unused));
#endif
dsl_dataset_t *ds;
uint64_t obj;
rrw_enter(&dp->dp_config_rwlock, RW_WRITER, FTAG);
/* create and open the MOS (meta-objset) */
dp->dp_meta_objset = dmu_objset_create_impl(spa,
NULL, &dp->dp_meta_rootbp, DMU_OST_META, tx);
spa->spa_meta_objset = dp->dp_meta_objset;
/* create the pool directory */
err = zap_create_claim(dp->dp_meta_objset, DMU_POOL_DIRECTORY_OBJECT,
DMU_OT_OBJECT_DIRECTORY, DMU_OT_NONE, 0, tx);
ASSERT0(err);
/* Initialize scan structures */
VERIFY0(dsl_scan_init(dp, txg));
/* create and open the root dir */
dp->dp_root_dir_obj = dsl_dir_create_sync(dp, NULL, NULL, tx);
VERIFY0(dsl_dir_hold_obj(dp, dp->dp_root_dir_obj,
NULL, dp, &dp->dp_root_dir));
/* create and open the meta-objset dir */
(void) dsl_dir_create_sync(dp, dp->dp_root_dir, MOS_DIR_NAME, tx);
VERIFY0(dsl_pool_open_special_dir(dp,
MOS_DIR_NAME, &dp->dp_mos_dir));
if (spa_version(spa) >= SPA_VERSION_DEADLISTS) {
/* create and open the free dir */
(void) dsl_dir_create_sync(dp, dp->dp_root_dir,
FREE_DIR_NAME, tx);
VERIFY0(dsl_pool_open_special_dir(dp,
FREE_DIR_NAME, &dp->dp_free_dir));
/* create and open the free_bplist */
obj = bpobj_alloc(dp->dp_meta_objset, SPA_OLD_MAXBLOCKSIZE, tx);
VERIFY(zap_add(dp->dp_meta_objset, DMU_POOL_DIRECTORY_OBJECT,
DMU_POOL_FREE_BPOBJ, sizeof (uint64_t), 1, &obj, tx) == 0);
VERIFY0(bpobj_open(&dp->dp_free_bpobj,
dp->dp_meta_objset, obj));
}
if (spa_version(spa) >= SPA_VERSION_DSL_SCRUB)
dsl_pool_create_origin(dp, tx);
/*
* Some features may be needed when creating the root dataset, so we
* create the feature objects here.
*/
if (spa_version(spa) >= SPA_VERSION_FEATURES)
spa_feature_create_zap_objects(spa, tx);
if (dcp != NULL && dcp->cp_crypt != ZIO_CRYPT_OFF &&
dcp->cp_crypt != ZIO_CRYPT_INHERIT)
spa_feature_enable(spa, SPA_FEATURE_ENCRYPTION, tx);
/* create the root dataset */
obj = dsl_dataset_create_sync_dd(dp->dp_root_dir, NULL, dcp, 0, tx);
/* create the root objset */
VERIFY0(dsl_dataset_hold_obj_flags(dp, obj,
DS_HOLD_FLAG_DECRYPT, FTAG, &ds));
rrw_enter(&ds->ds_bp_rwlock, RW_READER, FTAG);
os = dmu_objset_create_impl(dp->dp_spa, ds,
dsl_dataset_get_blkptr(ds), DMU_OST_ZFS, tx);
rrw_exit(&ds->ds_bp_rwlock, FTAG);
#ifdef _KERNEL
zfs_create_fs(os, kcred, zplprops, tx);
#endif
dsl_dataset_rele_flags(ds, DS_HOLD_FLAG_DECRYPT, FTAG);
dmu_tx_commit(tx);
rrw_exit(&dp->dp_config_rwlock, FTAG);
return (dp);
}
/*
* Account for the meta-objset space in its placeholder dsl_dir.
*/
void
dsl_pool_mos_diduse_space(dsl_pool_t *dp,
int64_t used, int64_t comp, int64_t uncomp)
{
ASSERT3U(comp, ==, uncomp); /* it's all metadata */
mutex_enter(&dp->dp_lock);
dp->dp_mos_used_delta += used;
dp->dp_mos_compressed_delta += comp;
dp->dp_mos_uncompressed_delta += uncomp;
mutex_exit(&dp->dp_lock);
}
static void
dsl_pool_sync_mos(dsl_pool_t *dp, dmu_tx_t *tx)
{
zio_t *zio = zio_root(dp->dp_spa, NULL, NULL, ZIO_FLAG_MUSTSUCCEED);
dmu_objset_sync(dp->dp_meta_objset, zio, tx);
VERIFY0(zio_wait(zio));
dprintf_bp(&dp->dp_meta_rootbp, "meta objset rootbp is %s", "");
spa_set_rootblkptr(dp->dp_spa, &dp->dp_meta_rootbp);
}
static void
dsl_pool_dirty_delta(dsl_pool_t *dp, int64_t delta)
{
ASSERT(MUTEX_HELD(&dp->dp_lock));
if (delta < 0)
ASSERT3U(-delta, <=, dp->dp_dirty_total);
dp->dp_dirty_total += delta;
/*
* Note: we signal even when increasing dp_dirty_total.
* This ensures forward progress -- each thread wakes the next waiter.
*/
if (dp->dp_dirty_total < zfs_dirty_data_max)
cv_signal(&dp->dp_spaceavail_cv);
}
#ifdef ZFS_DEBUG
static boolean_t
dsl_early_sync_task_verify(dsl_pool_t *dp, uint64_t txg)
{
spa_t *spa = dp->dp_spa;
vdev_t *rvd = spa->spa_root_vdev;
for (uint64_t c = 0; c < rvd->vdev_children; c++) {
vdev_t *vd = rvd->vdev_child[c];
txg_list_t *tl = &vd->vdev_ms_list;
metaslab_t *ms;
for (ms = txg_list_head(tl, TXG_CLEAN(txg)); ms;
ms = txg_list_next(tl, ms, TXG_CLEAN(txg))) {
VERIFY(range_tree_is_empty(ms->ms_freeing));
VERIFY(range_tree_is_empty(ms->ms_checkpointing));
}
}
return (B_TRUE);
}
#endif
void
dsl_pool_sync(dsl_pool_t *dp, uint64_t txg)
{
zio_t *zio;
dmu_tx_t *tx;
dsl_dir_t *dd;
dsl_dataset_t *ds;
objset_t *mos = dp->dp_meta_objset;
list_t synced_datasets;
list_create(&synced_datasets, sizeof (dsl_dataset_t),
offsetof(dsl_dataset_t, ds_synced_link));
tx = dmu_tx_create_assigned(dp, txg);
/*
* Run all early sync tasks before writing out any dirty blocks.
* For more info on early sync tasks see block comment in
* dsl_early_sync_task().
*/
if (!txg_list_empty(&dp->dp_early_sync_tasks, txg)) {
dsl_sync_task_t *dst;
ASSERT3U(spa_sync_pass(dp->dp_spa), ==, 1);
while ((dst =
txg_list_remove(&dp->dp_early_sync_tasks, txg)) != NULL) {
ASSERT(dsl_early_sync_task_verify(dp, txg));
dsl_sync_task_sync(dst, tx);
}
ASSERT(dsl_early_sync_task_verify(dp, txg));
}
/*
* Write out all dirty blocks of dirty datasets.
*/
zio = zio_root(dp->dp_spa, NULL, NULL, ZIO_FLAG_MUSTSUCCEED);
while ((ds = txg_list_remove(&dp->dp_dirty_datasets, txg)) != NULL) {
/*
* We must not sync any non-MOS datasets twice, because
* we may have taken a snapshot of them. However, we
* may sync newly-created datasets on pass 2.
*/
ASSERT(!list_link_active(&ds->ds_synced_link));
list_insert_tail(&synced_datasets, ds);
dsl_dataset_sync(ds, zio, tx);
}
VERIFY0(zio_wait(zio));
/*
* Update the long range free counter after
* we're done syncing user data
*/
mutex_enter(&dp->dp_lock);
ASSERT(spa_sync_pass(dp->dp_spa) == 1 ||
dp->dp_long_free_dirty_pertxg[txg & TXG_MASK] == 0);
dp->dp_long_free_dirty_pertxg[txg & TXG_MASK] = 0;
mutex_exit(&dp->dp_lock);
/*
* After the data blocks have been written (ensured by the zio_wait()
* above), update the user/group/project space accounting. This happens
* in tasks dispatched to dp_sync_taskq, so wait for them before
* continuing.
*/
for (ds = list_head(&synced_datasets); ds != NULL;
ds = list_next(&synced_datasets, ds)) {
dmu_objset_do_userquota_updates(ds->ds_objset, tx);
}
taskq_wait(dp->dp_sync_taskq);
/*
* Sync the datasets again to push out the changes due to
* userspace updates. This must be done before we process the
* sync tasks, so that any snapshots will have the correct
* user accounting information (and we won't get confused
* about which blocks are part of the snapshot).
*/
zio = zio_root(dp->dp_spa, NULL, NULL, ZIO_FLAG_MUSTSUCCEED);
while ((ds = txg_list_remove(&dp->dp_dirty_datasets, txg)) != NULL) {
objset_t *os = ds->ds_objset;
ASSERT(list_link_active(&ds->ds_synced_link));
dmu_buf_rele(ds->ds_dbuf, ds);
dsl_dataset_sync(ds, zio, tx);
/*
* Release any key mappings created by calls to
* dsl_dataset_dirty() from the userquota accounting
* code paths.
*/
if (os->os_encrypted && !os->os_raw_receive &&
!os->os_next_write_raw[txg & TXG_MASK]) {
ASSERT3P(ds->ds_key_mapping, !=, NULL);
key_mapping_rele(dp->dp_spa, ds->ds_key_mapping, ds);
}
}
VERIFY0(zio_wait(zio));
/*
* Now that the datasets have been completely synced, we can
* clean up our in-memory structures accumulated while syncing:
*
* - move dead blocks from the pending deadlist to the on-disk deadlist
* - release hold from dsl_dataset_dirty()
* - release key mapping hold from dsl_dataset_dirty()
*/
while ((ds = list_remove_head(&synced_datasets)) != NULL) {
objset_t *os = ds->ds_objset;
if (os->os_encrypted && !os->os_raw_receive &&
!os->os_next_write_raw[txg & TXG_MASK]) {
ASSERT3P(ds->ds_key_mapping, !=, NULL);
key_mapping_rele(dp->dp_spa, ds->ds_key_mapping, ds);
}
dsl_dataset_sync_done(ds, tx);
}
while ((dd = txg_list_remove(&dp->dp_dirty_dirs, txg)) != NULL) {
dsl_dir_sync(dd, tx);
}
/*
* The MOS's space is accounted for in the pool/$MOS
* (dp_mos_dir). We can't modify the mos while we're syncing
* it, so we remember the deltas and apply them here.
*/
if (dp->dp_mos_used_delta != 0 || dp->dp_mos_compressed_delta != 0 ||
dp->dp_mos_uncompressed_delta != 0) {
dsl_dir_diduse_space(dp->dp_mos_dir, DD_USED_HEAD,
dp->dp_mos_used_delta,
dp->dp_mos_compressed_delta,
dp->dp_mos_uncompressed_delta, tx);
dp->dp_mos_used_delta = 0;
dp->dp_mos_compressed_delta = 0;
dp->dp_mos_uncompressed_delta = 0;
}
if (!multilist_is_empty(mos->os_dirty_dnodes[txg & TXG_MASK])) {
dsl_pool_sync_mos(dp, tx);
}
/*
* We have written all of the accounted dirty data, so our
* dp_space_towrite should now be zero. However, some seldom-used
* code paths do not adhere to this (e.g. dbuf_undirty()). Shore up
* the accounting of any dirtied space now.
*
* Note that, besides any dirty data from datasets, the amount of
* dirty data in the MOS is also accounted by the pool. Therefore,
* we want to do this cleanup after dsl_pool_sync_mos() so we don't
* attempt to update the accounting for the same dirty data twice.
* (i.e. at this point we only update the accounting for the space
* that we know that we "leaked").
*/
dsl_pool_undirty_space(dp, dp->dp_dirty_pertxg[txg & TXG_MASK], txg);
/*
* If we modify a dataset in the same txg that we want to destroy it,
* its dsl_dir's dd_dbuf will be dirty, and thus have a hold on it.
* dsl_dir_destroy_check() will fail if there are unexpected holds.
* Therefore, we want to sync the MOS (thus syncing the dd_dbuf
* and clearing the hold on it) before we process the sync_tasks.
* The MOS data dirtied by the sync_tasks will be synced on the next
* pass.
*/
if (!txg_list_empty(&dp->dp_sync_tasks, txg)) {
dsl_sync_task_t *dst;
/*
* No more sync tasks should have been added while we
* were syncing.
*/
ASSERT3U(spa_sync_pass(dp->dp_spa), ==, 1);
while ((dst = txg_list_remove(&dp->dp_sync_tasks, txg)) != NULL)
dsl_sync_task_sync(dst, tx);
}
dmu_tx_commit(tx);
DTRACE_PROBE2(dsl_pool_sync__done, dsl_pool_t *dp, dp, uint64_t, txg);
}
void
dsl_pool_sync_done(dsl_pool_t *dp, uint64_t txg)
{
zilog_t *zilog;
while ((zilog = txg_list_head(&dp->dp_dirty_zilogs, txg))) {
dsl_dataset_t *ds = dmu_objset_ds(zilog->zl_os);
/*
* We don't remove the zilog from the dp_dirty_zilogs
* list until after we've cleaned it. This ensures that
* callers of zilog_is_dirty() receive an accurate
* answer when they are racing with the spa sync thread.
*/
zil_clean(zilog, txg);
(void) txg_list_remove_this(&dp->dp_dirty_zilogs, zilog, txg);
ASSERT(!dmu_objset_is_dirty(zilog->zl_os, txg));
dmu_buf_rele(ds->ds_dbuf, zilog);
}
ASSERT(!dmu_objset_is_dirty(dp->dp_meta_objset, txg));
}
/*
* TRUE if the current thread is the tx_sync_thread or if we
* are being called from SPA context during pool initialization.
*/
int
dsl_pool_sync_context(dsl_pool_t *dp)
{
return (curthread == dp->dp_tx.tx_sync_thread ||
spa_is_initializing(dp->dp_spa) ||
taskq_member(dp->dp_sync_taskq, curthread));
}
/*
* This function returns the amount of allocatable space in the pool
* minus whatever space is currently reserved by ZFS for specific
* purposes. Specifically:
*
* 1] Any reserved SLOP space
* 2] Any space used by the checkpoint
* 3] Any space used for deferred frees
*
* The latter 2 are especially important because they are needed to
* rectify the SPA's and DMU's different understanding of how much space
* is used. Now the DMU is aware of that extra space tracked by the SPA
* without having to maintain a separate special dir (e.g similar to
* $MOS, $FREEING, and $LEAKED).
*
* Note: By deferred frees here, we mean the frees that were deferred
* in spa_sync() after sync pass 1 (spa_deferred_bpobj), and not the
* segments placed in ms_defer trees during metaslab_sync_done().
*/
uint64_t
dsl_pool_adjustedsize(dsl_pool_t *dp, zfs_space_check_t slop_policy)
{
spa_t *spa = dp->dp_spa;
uint64_t space, resv, adjustedsize;
uint64_t spa_deferred_frees =
spa->spa_deferred_bpobj.bpo_phys->bpo_bytes;
space = spa_get_dspace(spa)
- spa_get_checkpoint_space(spa) - spa_deferred_frees;
resv = spa_get_slop_space(spa);
switch (slop_policy) {
case ZFS_SPACE_CHECK_NORMAL:
break;
case ZFS_SPACE_CHECK_RESERVED:
resv >>= 1;
break;
case ZFS_SPACE_CHECK_EXTRA_RESERVED:
resv >>= 2;
break;
case ZFS_SPACE_CHECK_NONE:
resv = 0;
break;
default:
panic("invalid slop policy value: %d", slop_policy);
break;
}
adjustedsize = (space >= resv) ? (space - resv) : 0;
return (adjustedsize);
}
uint64_t
dsl_pool_unreserved_space(dsl_pool_t *dp, zfs_space_check_t slop_policy)
{
uint64_t poolsize = dsl_pool_adjustedsize(dp, slop_policy);
uint64_t deferred =
metaslab_class_get_deferred(spa_normal_class(dp->dp_spa));
uint64_t quota = (poolsize >= deferred) ? (poolsize - deferred) : 0;
return (quota);
}
boolean_t
dsl_pool_need_dirty_delay(dsl_pool_t *dp)
{
uint64_t delay_min_bytes =
zfs_dirty_data_max * zfs_delay_min_dirty_percent / 100;
uint64_t dirty_min_bytes =
zfs_dirty_data_max * zfs_dirty_data_sync_percent / 100;
uint64_t dirty;
mutex_enter(&dp->dp_lock);
dirty = dp->dp_dirty_total;
mutex_exit(&dp->dp_lock);
if (dirty > dirty_min_bytes)
txg_kick(dp);
return (dirty > delay_min_bytes);
}
void
dsl_pool_dirty_space(dsl_pool_t *dp, int64_t space, dmu_tx_t *tx)
{
if (space > 0) {
mutex_enter(&dp->dp_lock);
dp->dp_dirty_pertxg[tx->tx_txg & TXG_MASK] += space;
dsl_pool_dirty_delta(dp, space);
mutex_exit(&dp->dp_lock);
}
}
void
dsl_pool_undirty_space(dsl_pool_t *dp, int64_t space, uint64_t txg)
{
ASSERT3S(space, >=, 0);
if (space == 0)
return;
mutex_enter(&dp->dp_lock);
if (dp->dp_dirty_pertxg[txg & TXG_MASK] < space) {
/* XXX writing something we didn't dirty? */
space = dp->dp_dirty_pertxg[txg & TXG_MASK];
}
ASSERT3U(dp->dp_dirty_pertxg[txg & TXG_MASK], >=, space);
dp->dp_dirty_pertxg[txg & TXG_MASK] -= space;
ASSERT3U(dp->dp_dirty_total, >=, space);
dsl_pool_dirty_delta(dp, -space);
mutex_exit(&dp->dp_lock);
}
/* ARGSUSED */
static int
upgrade_clones_cb(dsl_pool_t *dp, dsl_dataset_t *hds, void *arg)
{
dmu_tx_t *tx = arg;
dsl_dataset_t *ds, *prev = NULL;
int err;
err = dsl_dataset_hold_obj(dp, hds->ds_object, FTAG, &ds);
if (err)
return (err);
while (dsl_dataset_phys(ds)->ds_prev_snap_obj != 0) {
err = dsl_dataset_hold_obj(dp,
dsl_dataset_phys(ds)->ds_prev_snap_obj, FTAG, &prev);
if (err) {
dsl_dataset_rele(ds, FTAG);
return (err);
}
if (dsl_dataset_phys(prev)->ds_next_snap_obj != ds->ds_object)
break;
dsl_dataset_rele(ds, FTAG);
ds = prev;
prev = NULL;
}
if (prev == NULL) {
prev = dp->dp_origin_snap;
/*
* The $ORIGIN can't have any data, or the accounting
* will be wrong.
*/
rrw_enter(&ds->ds_bp_rwlock, RW_READER, FTAG);
ASSERT0(dsl_dataset_phys(prev)->ds_bp.blk_birth);
rrw_exit(&ds->ds_bp_rwlock, FTAG);
/* The origin doesn't get attached to itself */
if (ds->ds_object == prev->ds_object) {
dsl_dataset_rele(ds, FTAG);
return (0);
}
dmu_buf_will_dirty(ds->ds_dbuf, tx);
dsl_dataset_phys(ds)->ds_prev_snap_obj = prev->ds_object;
dsl_dataset_phys(ds)->ds_prev_snap_txg =
dsl_dataset_phys(prev)->ds_creation_txg;
dmu_buf_will_dirty(ds->ds_dir->dd_dbuf, tx);
dsl_dir_phys(ds->ds_dir)->dd_origin_obj = prev->ds_object;
dmu_buf_will_dirty(prev->ds_dbuf, tx);
dsl_dataset_phys(prev)->ds_num_children++;
if (dsl_dataset_phys(ds)->ds_next_snap_obj == 0) {
ASSERT(ds->ds_prev == NULL);
VERIFY0(dsl_dataset_hold_obj(dp,
dsl_dataset_phys(ds)->ds_prev_snap_obj,
ds, &ds->ds_prev));
}
}
ASSERT3U(dsl_dir_phys(ds->ds_dir)->dd_origin_obj, ==, prev->ds_object);
ASSERT3U(dsl_dataset_phys(ds)->ds_prev_snap_obj, ==, prev->ds_object);
if (dsl_dataset_phys(prev)->ds_next_clones_obj == 0) {
dmu_buf_will_dirty(prev->ds_dbuf, tx);
dsl_dataset_phys(prev)->ds_next_clones_obj =
zap_create(dp->dp_meta_objset,
DMU_OT_NEXT_CLONES, DMU_OT_NONE, 0, tx);
}
VERIFY0(zap_add_int(dp->dp_meta_objset,
dsl_dataset_phys(prev)->ds_next_clones_obj, ds->ds_object, tx));
dsl_dataset_rele(ds, FTAG);
if (prev != dp->dp_origin_snap)
dsl_dataset_rele(prev, FTAG);
return (0);
}
void
dsl_pool_upgrade_clones(dsl_pool_t *dp, dmu_tx_t *tx)
{
ASSERT(dmu_tx_is_syncing(tx));
ASSERT(dp->dp_origin_snap != NULL);
VERIFY0(dmu_objset_find_dp(dp, dp->dp_root_dir_obj, upgrade_clones_cb,
tx, DS_FIND_CHILDREN | DS_FIND_SERIALIZE));
}
/* ARGSUSED */
static int
upgrade_dir_clones_cb(dsl_pool_t *dp, dsl_dataset_t *ds, void *arg)
{
dmu_tx_t *tx = arg;
objset_t *mos = dp->dp_meta_objset;
if (dsl_dir_phys(ds->ds_dir)->dd_origin_obj != 0) {
dsl_dataset_t *origin;
VERIFY0(dsl_dataset_hold_obj(dp,
dsl_dir_phys(ds->ds_dir)->dd_origin_obj, FTAG, &origin));
if (dsl_dir_phys(origin->ds_dir)->dd_clones == 0) {
dmu_buf_will_dirty(origin->ds_dir->dd_dbuf, tx);
dsl_dir_phys(origin->ds_dir)->dd_clones =
zap_create(mos, DMU_OT_DSL_CLONES, DMU_OT_NONE,
0, tx);
}
VERIFY0(zap_add_int(dp->dp_meta_objset,
dsl_dir_phys(origin->ds_dir)->dd_clones,
ds->ds_object, tx));
dsl_dataset_rele(origin, FTAG);
}
return (0);
}
void
dsl_pool_upgrade_dir_clones(dsl_pool_t *dp, dmu_tx_t *tx)
{
uint64_t obj;
ASSERT(dmu_tx_is_syncing(tx));
(void) dsl_dir_create_sync(dp, dp->dp_root_dir, FREE_DIR_NAME, tx);
VERIFY0(dsl_pool_open_special_dir(dp,
FREE_DIR_NAME, &dp->dp_free_dir));
/*
* We can't use bpobj_alloc(), because spa_version() still
* returns the old version, and we need a new-version bpobj with
* subobj support. So call dmu_object_alloc() directly.
*/
obj = dmu_object_alloc(dp->dp_meta_objset, DMU_OT_BPOBJ,
SPA_OLD_MAXBLOCKSIZE, DMU_OT_BPOBJ_HDR, sizeof (bpobj_phys_t), tx);
VERIFY0(zap_add(dp->dp_meta_objset, DMU_POOL_DIRECTORY_OBJECT,
DMU_POOL_FREE_BPOBJ, sizeof (uint64_t), 1, &obj, tx));
VERIFY0(bpobj_open(&dp->dp_free_bpobj, dp->dp_meta_objset, obj));
VERIFY0(dmu_objset_find_dp(dp, dp->dp_root_dir_obj,
upgrade_dir_clones_cb, tx, DS_FIND_CHILDREN | DS_FIND_SERIALIZE));
}
void
dsl_pool_create_origin(dsl_pool_t *dp, dmu_tx_t *tx)
{
uint64_t dsobj;
dsl_dataset_t *ds;
ASSERT(dmu_tx_is_syncing(tx));
ASSERT(dp->dp_origin_snap == NULL);
ASSERT(rrw_held(&dp->dp_config_rwlock, RW_WRITER));
/* create the origin dir, ds, & snap-ds */
dsobj = dsl_dataset_create_sync(dp->dp_root_dir, ORIGIN_DIR_NAME,
NULL, 0, kcred, NULL, tx);
VERIFY0(dsl_dataset_hold_obj(dp, dsobj, FTAG, &ds));
dsl_dataset_snapshot_sync_impl(ds, ORIGIN_DIR_NAME, tx);
VERIFY0(dsl_dataset_hold_obj(dp, dsl_dataset_phys(ds)->ds_prev_snap_obj,
dp, &dp->dp_origin_snap));
dsl_dataset_rele(ds, FTAG);
}
taskq_t *
dsl_pool_iput_taskq(dsl_pool_t *dp)
{
return (dp->dp_iput_taskq);
}
taskq_t *
dsl_pool_unlinked_drain_taskq(dsl_pool_t *dp)
{
return (dp->dp_unlinked_drain_taskq);
}
/*
* Walk through the pool-wide zap object of temporary snapshot user holds
* and release them.
*/
void
dsl_pool_clean_tmp_userrefs(dsl_pool_t *dp)
{
zap_attribute_t za;
zap_cursor_t zc;
objset_t *mos = dp->dp_meta_objset;
uint64_t zapobj = dp->dp_tmp_userrefs_obj;
nvlist_t *holds;
if (zapobj == 0)
return;
ASSERT(spa_version(dp->dp_spa) >= SPA_VERSION_USERREFS);
holds = fnvlist_alloc();
for (zap_cursor_init(&zc, mos, zapobj);
zap_cursor_retrieve(&zc, &za) == 0;
zap_cursor_advance(&zc)) {
char *htag;
nvlist_t *tags;
htag = strchr(za.za_name, '-');
*htag = '\0';
++htag;
if (nvlist_lookup_nvlist(holds, za.za_name, &tags) != 0) {
tags = fnvlist_alloc();
fnvlist_add_boolean(tags, htag);
fnvlist_add_nvlist(holds, za.za_name, tags);
fnvlist_free(tags);
} else {
fnvlist_add_boolean(tags, htag);
}
}
dsl_dataset_user_release_tmp(dp, holds);
fnvlist_free(holds);
zap_cursor_fini(&zc);
}
/*
* Create the pool-wide zap object for storing temporary snapshot holds.
*/
void
dsl_pool_user_hold_create_obj(dsl_pool_t *dp, dmu_tx_t *tx)
{
objset_t *mos = dp->dp_meta_objset;
ASSERT(dp->dp_tmp_userrefs_obj == 0);
ASSERT(dmu_tx_is_syncing(tx));
dp->dp_tmp_userrefs_obj = zap_create_link(mos, DMU_OT_USERREFS,
DMU_POOL_DIRECTORY_OBJECT, DMU_POOL_TMP_USERREFS, tx);
}
static int
dsl_pool_user_hold_rele_impl(dsl_pool_t *dp, uint64_t dsobj,
const char *tag, uint64_t now, dmu_tx_t *tx, boolean_t holding)
{
objset_t *mos = dp->dp_meta_objset;
uint64_t zapobj = dp->dp_tmp_userrefs_obj;
char *name;
int error;
ASSERT(spa_version(dp->dp_spa) >= SPA_VERSION_USERREFS);
ASSERT(dmu_tx_is_syncing(tx));
/*
* If the pool was created prior to SPA_VERSION_USERREFS, the
* zap object for temporary holds might not exist yet.
*/
if (zapobj == 0) {
if (holding) {
dsl_pool_user_hold_create_obj(dp, tx);
zapobj = dp->dp_tmp_userrefs_obj;
} else {
return (SET_ERROR(ENOENT));
}
}
name = kmem_asprintf("%llx-%s", (u_longlong_t)dsobj, tag);
if (holding)
error = zap_add(mos, zapobj, name, 8, 1, &now, tx);
else
error = zap_remove(mos, zapobj, name, tx);
strfree(name);
return (error);
}
/*
* Add a temporary hold for the given dataset object and tag.
*/
int
dsl_pool_user_hold(dsl_pool_t *dp, uint64_t dsobj, const char *tag,
uint64_t now, dmu_tx_t *tx)
{
return (dsl_pool_user_hold_rele_impl(dp, dsobj, tag, now, tx, B_TRUE));
}
/*
* Release a temporary hold for the given dataset object and tag.
*/
int
dsl_pool_user_release(dsl_pool_t *dp, uint64_t dsobj, const char *tag,
dmu_tx_t *tx)
{
return (dsl_pool_user_hold_rele_impl(dp, dsobj, tag, 0,
tx, B_FALSE));
}
/*
* DSL Pool Configuration Lock
*
* The dp_config_rwlock protects against changes to DSL state (e.g. dataset
* creation / destruction / rename / property setting). It must be held for
* read to hold a dataset or dsl_dir. I.e. you must call
* dsl_pool_config_enter() or dsl_pool_hold() before calling
* dsl_{dataset,dir}_hold{_obj}. In most circumstances, the dp_config_rwlock
* must be held continuously until all datasets and dsl_dirs are released.
*
* The only exception to this rule is that if a "long hold" is placed on
* a dataset, then the dp_config_rwlock may be dropped while the dataset
* is still held. The long hold will prevent the dataset from being
* destroyed -- the destroy will fail with EBUSY. A long hold can be
* obtained by calling dsl_dataset_long_hold(), or by "owning" a dataset
* (by calling dsl_{dataset,objset}_{try}own{_obj}).
*
* Legitimate long-holders (including owners) should be long-running, cancelable
* tasks that should cause "zfs destroy" to fail. This includes DMU
* consumers (i.e. a ZPL filesystem being mounted or ZVOL being open),
* "zfs send", and "zfs diff". There are several other long-holders whose
* uses are suboptimal (e.g. "zfs promote", and zil_suspend()).
*
* The usual formula for long-holding would be:
* dsl_pool_hold()
* dsl_dataset_hold()
* ... perform checks ...
* dsl_dataset_long_hold()
* dsl_pool_rele()
* ... perform long-running task ...
* dsl_dataset_long_rele()
* dsl_dataset_rele()
*
* Note that when the long hold is released, the dataset is still held but
* the pool is not held. The dataset may change arbitrarily during this time
* (e.g. it could be destroyed). Therefore you shouldn't do anything to the
* dataset except release it.
*
* User-initiated operations (e.g. ioctls, zfs_ioc_*()) are either read-only
* or modifying operations.
*
* Modifying operations should generally use dsl_sync_task(). The synctask
* infrastructure enforces proper locking strategy with respect to the
* dp_config_rwlock. See the comment above dsl_sync_task() for details.
*
* Read-only operations will manually hold the pool, then the dataset, obtain
* information from the dataset, then release the pool and dataset.
* dmu_objset_{hold,rele}() are convenience routines that also do the pool
* hold/rele.
*/
int
dsl_pool_hold(const char *name, void *tag, dsl_pool_t **dp)
{
spa_t *spa;
int error;
error = spa_open(name, &spa, tag);
if (error == 0) {
*dp = spa_get_dsl(spa);
dsl_pool_config_enter(*dp, tag);
}
return (error);
}
void
dsl_pool_rele(dsl_pool_t *dp, void *tag)
{
dsl_pool_config_exit(dp, tag);
spa_close(dp->dp_spa, tag);
}
void
dsl_pool_config_enter(dsl_pool_t *dp, void *tag)
{
/*
* We use a "reentrant" reader-writer lock, but not reentrantly.
*
* The rrwlock can (with the track_all flag) track all reading threads,
* which is very useful for debugging which code path failed to release
* the lock, and for verifying that the *current* thread does hold
* the lock.
*
* (Unlike a rwlock, which knows that N threads hold it for
* read, but not *which* threads, so rw_held(RW_READER) returns TRUE
* if any thread holds it for read, even if this thread doesn't).
*/
ASSERT(!rrw_held(&dp->dp_config_rwlock, RW_READER));
rrw_enter(&dp->dp_config_rwlock, RW_READER, tag);
}
void
dsl_pool_config_enter_prio(dsl_pool_t *dp, void *tag)
{
ASSERT(!rrw_held(&dp->dp_config_rwlock, RW_READER));
rrw_enter_read_prio(&dp->dp_config_rwlock, tag);
}
void
dsl_pool_config_exit(dsl_pool_t *dp, void *tag)
{
rrw_exit(&dp->dp_config_rwlock, tag);
}
boolean_t
dsl_pool_config_held(dsl_pool_t *dp)
{
return (RRW_LOCK_HELD(&dp->dp_config_rwlock));
}
boolean_t
dsl_pool_config_held_writer(dsl_pool_t *dp)
{
return (RRW_WRITE_HELD(&dp->dp_config_rwlock));
}
#if defined(_KERNEL)
EXPORT_SYMBOL(dsl_pool_config_enter);
EXPORT_SYMBOL(dsl_pool_config_exit);
/* BEGIN CSTYLED */
/* zfs_dirty_data_max_percent only applied at module load in arc_init(). */
module_param(zfs_dirty_data_max_percent, int, 0444);
MODULE_PARM_DESC(zfs_dirty_data_max_percent, "percent of ram can be dirty");
/* zfs_dirty_data_max_max_percent only applied at module load in arc_init(). */
module_param(zfs_dirty_data_max_max_percent, int, 0444);
MODULE_PARM_DESC(zfs_dirty_data_max_max_percent,
"zfs_dirty_data_max upper bound as % of RAM");
module_param(zfs_delay_min_dirty_percent, int, 0644);
MODULE_PARM_DESC(zfs_delay_min_dirty_percent, "transaction delay threshold");
module_param(zfs_dirty_data_max, ulong, 0644);
MODULE_PARM_DESC(zfs_dirty_data_max, "determines the dirty space limit");
/* zfs_dirty_data_max_max only applied at module load in arc_init(). */
module_param(zfs_dirty_data_max_max, ulong, 0444);
MODULE_PARM_DESC(zfs_dirty_data_max_max,
"zfs_dirty_data_max upper bound in bytes");
module_param(zfs_dirty_data_sync_percent, int, 0644);
MODULE_PARM_DESC(zfs_dirty_data_sync_percent,
"dirty data txg sync threshold as a percentage of zfs_dirty_data_max");
module_param(zfs_delay_scale, ulong, 0644);
MODULE_PARM_DESC(zfs_delay_scale, "how quickly delay approaches infinity");
module_param(zfs_sync_taskq_batch_pct, int, 0644);
MODULE_PARM_DESC(zfs_sync_taskq_batch_pct,
"max percent of CPUs that are used to sync dirty data");
module_param(zfs_zil_clean_taskq_nthr_pct, int, 0644);
MODULE_PARM_DESC(zfs_zil_clean_taskq_nthr_pct,
"max percent of CPUs that are used per dp_sync_taskq");
module_param(zfs_zil_clean_taskq_minalloc, int, 0644);
MODULE_PARM_DESC(zfs_zil_clean_taskq_minalloc,
"number of taskq entries that are pre-populated");
module_param(zfs_zil_clean_taskq_maxalloc, int, 0644);
MODULE_PARM_DESC(zfs_zil_clean_taskq_maxalloc,
"max number of taskq entries that are cached");
/* END CSTYLED */
#endif
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