ZFS/MFV: Use cached feature info in spa_add_feature_stats()
commit 417104bdd3
Author: Ned Bass <bass6@llnl.gov>
Date: Thu Feb 26 12:24:11 2015 -0800
Use cached feature info in spa_add_feature_stats()
Avoid issuing I/O to the pool when retrieving feature flags information.
Trying to read the ZAPs from disk means that zpool clear would hang if
the pool is suspended and recovery would require a reboot. To keep the
feature stats resident in memory, we hang a cached nvlist off of the
spa. It is built up from disk the first time spa_add_feature_stats() is
called, and refreshed thereafter using the cached feature reference
counts. spa_add_feature_stats() gets called at pool import time so we
can be sure the cached nvlist will be available if the pool is later
suspended.
Signed-off-by: Ned Bass <bass6@llnl.gov>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #3082
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Notes:
svn2git
2020-12-20 02:59:44 +00:00
svn path=/head/; revision=337594
@ -4371,18 +4371,14 @@ spa_add_l2cache(spa_t *spa, nvlist_t *config)
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}
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static void
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spa_add_feature_stats(spa_t *spa, nvlist_t *config)
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spa_feature_stats_from_disk(spa_t *spa, nvlist_t *features)
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{
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nvlist_t *features;
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zap_cursor_t zc;
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zap_attribute_t za;
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ASSERT(spa_config_held(spa, SCL_CONFIG, RW_READER));
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VERIFY(nvlist_alloc(&features, NV_UNIQUE_NAME, KM_SLEEP) == 0);
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/* We may be unable to read features if pool is suspended. */
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if (spa_suspended(spa))
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goto out;
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return;
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if (spa->spa_feat_for_read_obj != 0) {
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for (zap_cursor_init(&zc, spa->spa_meta_objset,
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@ -4391,7 +4387,7 @@ spa_add_feature_stats(spa_t *spa, nvlist_t *config)
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zap_cursor_advance(&zc)) {
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ASSERT(za.za_integer_length == sizeof (uint64_t) &&
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za.za_num_integers == 1);
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VERIFY3U(0, ==, nvlist_add_uint64(features, za.za_name,
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VERIFY0(nvlist_add_uint64(features, za.za_name,
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za.za_first_integer));
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}
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zap_cursor_fini(&zc);
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@ -4404,16 +4400,62 @@ spa_add_feature_stats(spa_t *spa, nvlist_t *config)
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zap_cursor_advance(&zc)) {
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ASSERT(za.za_integer_length == sizeof (uint64_t) &&
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za.za_num_integers == 1);
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VERIFY3U(0, ==, nvlist_add_uint64(features, za.za_name,
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VERIFY0(nvlist_add_uint64(features, za.za_name,
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za.za_first_integer));
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}
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zap_cursor_fini(&zc);
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}
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}
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out:
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VERIFY(nvlist_add_nvlist(config, ZPOOL_CONFIG_FEATURE_STATS,
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features) == 0);
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nvlist_free(features);
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static void
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spa_feature_stats_from_cache(spa_t *spa, nvlist_t *features)
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{
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int i;
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for (i = 0; i < SPA_FEATURES; i++) {
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zfeature_info_t feature = spa_feature_table[i];
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uint64_t refcount;
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if (feature_get_refcount(spa, &feature, &refcount) != 0)
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continue;
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VERIFY0(nvlist_add_uint64(features, feature.fi_guid, refcount));
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}
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}
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/*
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* Store a list of pool features and their reference counts in the
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* config.
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*
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* The first time this is called on a spa, allocate a new nvlist, fetch
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* the pool features and reference counts from disk, then save the list
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* in the spa. In subsequent calls on the same spa use the saved nvlist
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* and refresh its values from the cached reference counts. This
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* ensures we don't block here on I/O on a suspended pool so 'zpool
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* clear' can resume the pool.
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*/
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static void
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spa_add_feature_stats(spa_t *spa, nvlist_t *config)
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{
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nvlist_t *features;
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ASSERT(spa_config_held(spa, SCL_CONFIG, RW_READER));
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mutex_enter(&spa->spa_feat_stats_lock);
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features = spa->spa_feat_stats;
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if (features != NULL) {
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spa_feature_stats_from_cache(spa, features);
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} else {
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VERIFY0(nvlist_alloc(&features, NV_UNIQUE_NAME, KM_SLEEP));
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spa->spa_feat_stats = features;
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spa_feature_stats_from_disk(spa, features);
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}
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VERIFY0(nvlist_add_nvlist(config, ZPOOL_CONFIG_FEATURE_STATS,
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features));
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mutex_exit(&spa->spa_feat_stats_lock);
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}
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int
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@ -708,6 +708,7 @@ spa_add(const char *name, nvlist_t *config, const char *altroot)
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mutex_init(&spa->spa_scrub_lock, NULL, MUTEX_DEFAULT, NULL);
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mutex_init(&spa->spa_suspend_lock, NULL, MUTEX_DEFAULT, NULL);
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mutex_init(&spa->spa_vdev_top_lock, NULL, MUTEX_DEFAULT, NULL);
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mutex_init(&spa->spa_feat_stats_lock, NULL, MUTEX_DEFAULT, NULL);
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cv_init(&spa->spa_async_cv, NULL, CV_DEFAULT, NULL);
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cv_init(&spa->spa_evicting_os_cv, NULL, CV_DEFAULT, NULL);
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@ -881,6 +882,7 @@ spa_remove(spa_t *spa)
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nvlist_free(spa->spa_label_features);
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nvlist_free(spa->spa_load_info);
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nvlist_free(spa->spa_feat_stats);
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spa_config_set(spa, NULL);
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#ifdef illumos
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@ -922,6 +924,7 @@ spa_remove(spa_t *spa)
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mutex_destroy(&spa->spa_scrub_lock);
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mutex_destroy(&spa->spa_suspend_lock);
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mutex_destroy(&spa->spa_vdev_top_lock);
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mutex_destroy(&spa->spa_feat_stats_lock);
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kmem_free(spa, sizeof (spa_t));
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}
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@ -360,6 +360,8 @@ struct spa {
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uint64_t spa_feat_for_read_obj; /* required to read from pool */
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uint64_t spa_feat_desc_obj; /* Feature descriptions */
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uint64_t spa_feat_enabled_txg_obj; /* Feature enabled txg */
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kmutex_t spa_feat_stats_lock; /* protects spa_feat_stats */
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nvlist_t *spa_feat_stats; /* Cache of enabled features */
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/* cache feature refcounts */
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uint64_t spa_feat_refcount_cache[SPA_FEATURES];
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#ifdef illumos
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@ -220,7 +220,7 @@ spa_features_check(spa_t *spa, boolean_t for_write,
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*
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* Note: well-designed features will not need to use this; they should
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* use spa_feature_is_enabled() and spa_feature_is_active() instead.
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* However, this is non-static for zdb and zhack.
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* However, this is non-static for zdb, zhack, and spa_add_feature_stats().
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*/
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int
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feature_get_refcount(spa_t *spa, zfeature_info_t *feature, uint64_t *res)
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