module/zfs/dataset_kstats.c

   1 /*
   2  * CDDL HEADER START
   3  *
   4  * The contents of this file are subject to the terms of the
   5  * Common Development and Distribution License (the "License").
   6  * You may not use this file except in compliance with the License.
   7  *
   8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
   9  * or http://www.opensolaris.org/os/licensing.
  10  * See the License for the specific language governing permissions
  11  * and limitations under the License.
  12  *
  13  * When distributing Covered Code, include this CDDL HEADER in each
  14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
  15  * If applicable, add the following below this CDDL HEADER, with the
  16  * fields enclosed by brackets "[]" replaced with your own identifying
  17  * information: Portions Copyright [yyyy] [name of copyright owner]
  18  *
  19  * CDDL HEADER END
  20  */
  21
  22 /*
  23  * Copyright (c) 2018 by Delphix. All rights reserved.
  24  */
  25
  26 #include <sys/dataset_kstats.h>
  27 #include <sys/dmu_objset.h>
  28 #include <sys/dsl_dataset.h>
  29 #include <sys/spa.h>
  30
  31 static dataset_kstat_values_t empty_dataset_kstats = {
  32         { "dataset_name",       KSTAT_DATA_STRING },
  33         { "writes",     KSTAT_DATA_UINT64 },
  34         { "nwritten",   KSTAT_DATA_UINT64 },
  35         { "reads",      KSTAT_DATA_UINT64 },
  36         { "nread",      KSTAT_DATA_UINT64 },
  37 };
  38
  39 static int
  40 dataset_kstats_update(kstat_t *ksp, int rw)
  41 {
  42         dataset_kstats_t *dk = ksp->ks_private;
  43         ASSERT3P(dk->dk_kstats->ks_data, ==, ksp->ks_data);
  44
  45         if (rw == KSTAT_WRITE)
  46                 return (EACCES);
  47
  48         dataset_kstat_values_t *dkv = dk->dk_kstats->ks_data;
  49         dkv->dkv_writes.value.ui64 =
  50             aggsum_value(&dk->dk_aggsums.das_writes);
  51         dkv->dkv_nwritten.value.ui64 =
  52             aggsum_value(&dk->dk_aggsums.das_nwritten);
  53         dkv->dkv_reads.value.ui64 =
  54             aggsum_value(&dk->dk_aggsums.das_reads);
  55         dkv->dkv_nread.value.ui64 =
  56             aggsum_value(&dk->dk_aggsums.das_nread);
  57
  58         return (0);
  59 }
  60
  61 void
  62 dataset_kstats_create(dataset_kstats_t *dk, objset_t *objset)
  63 {
  64         /*
  65          * There should not be anything wrong with having kstats for
  66          * snapshots. Since we are not sure how useful they would be
  67          * though nor how much their memory overhead would matter in
  68          * a filesystem with many snapshots, we skip them for now.
  69          */
  70         if (dmu_objset_is_snapshot(objset))
  71                 return;
  72
  73         /*
  74          * At the time of this writing, KSTAT_STRLEN is 255 in Linux,
  75          * and the spa_name can theoretically be up to 256 characters.
  76          * In reality though the spa_name can be 240 characters max
  77          * [see origin directory name check in pool_namecheck()]. Thus,
  78          * the naming scheme for the module name below should not cause
  79          * any truncations. In the event that a truncation does happen
  80          * though, due to some future change, we silently skip creating
  81          * the kstat and log the event.
  82          */
  83         char kstat_module_name[KSTAT_STRLEN];
  84         int n = snprintf(kstat_module_name, sizeof (kstat_module_name),
  85             "zfs/%s", spa_name(dmu_objset_spa(objset)));
  86         if (n < 0) {
  87                 zfs_dbgmsg("failed to create dataset kstat for objset %lld: "
  88                     " snprintf() for kstat module name returned %d",
  89                     (unsigned long long)dmu_objset_id(objset), n);
  90                 return;
  91         } else if (n >= KSTAT_STRLEN) {
  92                 zfs_dbgmsg("failed to create dataset kstat for objset %lld: "
  93                     "kstat module name length (%d) exceeds limit (%d)",
  94                     (unsigned long long)dmu_objset_id(objset),
  95                     n, KSTAT_STRLEN);
  96                 return;
  97         }
  98
  99         char kstat_name[KSTAT_STRLEN];
 100         n = snprintf(kstat_name, sizeof (kstat_name), "objset-0x%llx",
 101             (unsigned long long)dmu_objset_id(objset));
 102         if (n < 0) {
 103                 zfs_dbgmsg("failed to create dataset kstat for objset %lld: "
 104                     " snprintf() for kstat name returned %d",
 105                     (unsigned long long)dmu_objset_id(objset), n);
 106                 return;
 107         }
 108         ASSERT3U(n, <, KSTAT_STRLEN);
 109
 110         kstat_t *kstat = kstat_create(kstat_module_name, 0, kstat_name,
 111             "dataset", KSTAT_TYPE_NAMED,
 112             sizeof (empty_dataset_kstats) / sizeof (kstat_named_t),
 113             KSTAT_FLAG_VIRTUAL);
 114         if (kstat == NULL)
 115                 return;
 116
 117         dataset_kstat_values_t *dk_kstats =
 118             kmem_alloc(sizeof (empty_dataset_kstats), KM_SLEEP);
 119         bcopy(&empty_dataset_kstats, dk_kstats,
 120             sizeof (empty_dataset_kstats));
 121
 122         char *ds_name = kmem_zalloc(ZFS_MAX_DATASET_NAME_LEN, KM_SLEEP);
 123         dsl_dataset_name(objset->os_dsl_dataset, ds_name);
 124         KSTAT_NAMED_STR_PTR(&dk_kstats->dkv_ds_name) = ds_name;
 125         KSTAT_NAMED_STR_BUFLEN(&dk_kstats->dkv_ds_name) =
 126             ZFS_MAX_DATASET_NAME_LEN;
 127
 128         kstat->ks_data = dk_kstats;
 129         kstat->ks_update = dataset_kstats_update;
 130         kstat->ks_private = dk;
 131
 132         kstat_install(kstat);
 133         dk->dk_kstats = kstat;
 134
 135         aggsum_init(&dk->dk_aggsums.das_writes, 0);
 136         aggsum_init(&dk->dk_aggsums.das_nwritten, 0);
 137         aggsum_init(&dk->dk_aggsums.das_reads, 0);
 138         aggsum_init(&dk->dk_aggsums.das_nread, 0);
 139 }
 140
 141 void
 142 dataset_kstats_destroy(dataset_kstats_t *dk)
 143 {
 144         if (dk->dk_kstats == NULL)
 145                 return;
 146
 147         dataset_kstat_values_t *dkv = dk->dk_kstats->ks_data;
 148         kmem_free(KSTAT_NAMED_STR_PTR(&dkv->dkv_ds_name),
 149             KSTAT_NAMED_STR_BUFLEN(&dkv->dkv_ds_name));
 150         kmem_free(dkv, sizeof (empty_dataset_kstats));
 151
 152         kstat_delete(dk->dk_kstats);
 153         dk->dk_kstats = NULL;
 154
 155         aggsum_fini(&dk->dk_aggsums.das_writes);
 156         aggsum_fini(&dk->dk_aggsums.das_nwritten);
 157         aggsum_fini(&dk->dk_aggsums.das_reads);
 158         aggsum_fini(&dk->dk_aggsums.das_nread);
 159 }
 160
 161 void
 162 dataset_kstats_update_write_kstats(dataset_kstats_t *dk,
 163     int64_t nwritten)
 164 {
 165         ASSERT3S(nwritten, >=, 0);
 166
 167         if (dk->dk_kstats == NULL)
 168                 return;
 169
 170         aggsum_add(&dk->dk_aggsums.das_writes, 1);
 171         aggsum_add(&dk->dk_aggsums.das_nwritten, nwritten);
 172 }
 173
 174 void
 175 dataset_kstats_update_read_kstats(dataset_kstats_t *dk,
 176     int64_t nread)
 177 {
 178         ASSERT3S(nread, >=, 0);
 179
 180         if (dk->dk_kstats == NULL)
 181                 return;
 182
 183         aggsum_add(&dk->dk_aggsums.das_reads, 1);
 184         aggsum_add(&dk->dk_aggsums.das_nread, nread);
 185 }