Include class name into struct metaslab_class

With increasing number of metaslab classes it can be helpful for
debugging to know what we are looking at.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Rob Norris <rob.norris@klarasystems.com>
Signed-off-by:	Alexander Motin <mav@FreeBSD.org>
Sponsored by:	iXsystems, Inc.
Closes #17409

include/sys/metaslab.h

@@ -102,8 +102,8 @@ void metaslab_trace_move(zio_alloc_list_t *, zio_alloc_list_t *);
 void metaslab_trace_init(zio_alloc_list_t *);
 void metaslab_trace_fini(zio_alloc_list_t *);
 
-metaslab_class_t *metaslab_class_create(spa_t *, const metaslab_ops_t *,
+metaslab_class_t *metaslab_class_create(spa_t *, const char *,
-    boolean_t);
+    const metaslab_ops_t *, boolean_t);
 void metaslab_class_destroy(metaslab_class_t *);
 void metaslab_class_validate(metaslab_class_t *);
 void metaslab_class_balance(metaslab_class_t *mc, boolean_t onsync);
@@ -114,6 +114,7 @@ boolean_t metaslab_class_throttle_reserve(metaslab_class_t *, int, zio_t *,
     boolean_t, boolean_t *);
 boolean_t metaslab_class_throttle_unreserve(metaslab_class_t *, int, zio_t *);
 void metaslab_class_evict_old(metaslab_class_t *, uint64_t);
+const char *metaslab_class_get_name(metaslab_class_t *);
 uint64_t metaslab_class_get_alloc(metaslab_class_t *);
 uint64_t metaslab_class_get_space(metaslab_class_t *);
 uint64_t metaslab_class_get_dspace(metaslab_class_t *);

include/sys/metaslab_impl.h

@@ -181,7 +181,8 @@ typedef struct metaslab_class_allocator {
 struct metaslab_class {
 	kmutex_t		mc_lock;
 	spa_t			*mc_spa;
-	const metaslab_ops_t		*mc_ops;
+	const char		*mc_name;
+	const metaslab_ops_t	*mc_ops;
 
 	/*
 	 * Track the number of metaslab groups that have been initialized

module/zfs/metaslab.c

@@ -412,7 +412,8 @@ metaslab_stat_fini(void)
  * ==========================================================================
  */
 metaslab_class_t *
-metaslab_class_create(spa_t *spa, const metaslab_ops_t *ops, boolean_t is_log)
+metaslab_class_create(spa_t *spa, const char *name,
+    const metaslab_ops_t *ops, boolean_t is_log)
 {
 	metaslab_class_t *mc;
 
@@ -420,6 +421,7 @@ metaslab_class_create(spa_t *spa, const metaslab_ops_t *ops, boolean_t is_log)
 	    mc_allocator[spa->spa_alloc_count]), KM_SLEEP);
 
 	mc->mc_spa = spa;
+	mc->mc_name = name;
 	mc->mc_ops = ops;
 	mc->mc_is_log = is_log;
 	mc->mc_alloc_io_size = SPA_OLD_MAXBLOCKSIZE;
@@ -689,6 +691,12 @@ metaslab_class_space_update(metaslab_class_t *mc, int64_t alloc_delta,
 	atomic_add_64(&mc->mc_dspace, dspace_delta);
 }
 
+const char *
+metaslab_class_get_name(metaslab_class_t *mc)
+{
+	return (mc->mc_name);
+}
+
 uint64_t
 metaslab_class_get_alloc(metaslab_class_t *mc)
 {
@@ -2631,7 +2639,7 @@ metaslab_load_impl(metaslab_t *msp)
 	ASSERT3U(max_size, <=, msp->ms_max_size);
 	hrtime_t load_end = gethrtime();
 	msp->ms_load_time = load_end;
-	zfs_dbgmsg("metaslab_load: txg %llu, spa %s, vdev_id %llu, "
+	zfs_dbgmsg("metaslab_load: txg %llu, spa %s, class %s, vdev_id %llu, "
 	    "ms_id %llu, smp_length %llu, "
 	    "unflushed_allocs %llu, unflushed_frees %llu, "
 	    "freed %llu, defer %llu + %llu, unloaded time %llu ms, "
@@ -2639,6 +2647,7 @@ metaslab_load_impl(metaslab_t *msp)
 	    "max size error %lld, "
 	    "old_weight %llx, new_weight %llx",
 	    (u_longlong_t)spa_syncing_txg(spa), spa_name(spa),
+	    msp->ms_group->mg_class->mc_name,
 	    (u_longlong_t)msp->ms_group->mg_vd->vdev_id,
 	    (u_longlong_t)msp->ms_id,
 	    (u_longlong_t)space_map_length(msp->ms_sm),
@@ -2744,11 +2753,12 @@ metaslab_unload(metaslab_t *msp)
 		multilist_sublist_unlock(mls);
 
 		spa_t *spa = msp->ms_group->mg_vd->vdev_spa;
-		zfs_dbgmsg("metaslab_unload: txg %llu, spa %s, vdev_id %llu, "
+		zfs_dbgmsg("metaslab_unload: txg %llu, spa %s, class %s, "
-		    "ms_id %llu, weight %llx, "
+		    "vdev_id %llu, ms_id %llu, weight %llx, "
 		    "selected txg %llu (%llu s ago), alloc_txg %llu, "
 		    "loaded %llu ms ago, max_size %llu",
 		    (u_longlong_t)spa_syncing_txg(spa), spa_name(spa),
+		    msp->ms_group->mg_class->mc_name,
 		    (u_longlong_t)msp->ms_group->mg_vd->vdev_id,
 		    (u_longlong_t)msp->ms_id,
 		    (u_longlong_t)msp->ms_weight,

module/zfs/spa.c

@@ -1687,11 +1687,15 @@ spa_activate(spa_t *spa, spa_mode_t mode)
 	spa->spa_mode = mode;
 	spa->spa_read_spacemaps = spa_mode_readable_spacemaps;
 
-	spa->spa_normal_class = metaslab_class_create(spa, msp, B_FALSE);
+	spa->spa_normal_class = metaslab_class_create(spa, "normal",
-	spa->spa_log_class = metaslab_class_create(spa, msp, B_TRUE);
+	    msp, B_FALSE);
-	spa->spa_embedded_log_class = metaslab_class_create(spa, msp, B_TRUE);
+	spa->spa_log_class = metaslab_class_create(spa, "log", msp, B_TRUE);
-	spa->spa_special_class = metaslab_class_create(spa, msp, B_FALSE);
+	spa->spa_embedded_log_class = metaslab_class_create(spa,
-	spa->spa_dedup_class = metaslab_class_create(spa, msp, B_FALSE);
+	    "embedded_log", msp, B_TRUE);
+	spa->spa_special_class = metaslab_class_create(spa, "special",
+	    msp, B_FALSE);
+	spa->spa_dedup_class = metaslab_class_create(spa, "dedup",
+	    msp, B_FALSE);
 
 	/* Try to create a covering process */
 	mutex_enter(&spa->spa_proc_lock);

module/zfs/zio.c

@@ -4221,7 +4221,7 @@ again:
 		zfs_dbgmsg("%s[%llu]: %s class spilling, req size %llu, "
 		    "%llu allocated of %llu",
 		    spa_name(spa), (u_longlong_t)zio->io_txg,
-		    mc == spa_dedup_class(spa) ? "dedup" : "special",
+		    metaslab_class_get_name(mc),
 		    (u_longlong_t)zio->io_size,
 		    (u_longlong_t)metaslab_class_get_alloc(mc),
 		    (u_longlong_t)metaslab_class_get_space(mc));
@@ -4245,10 +4245,12 @@ again:
 		}
 
 		if (zfs_flags & ZFS_DEBUG_METASLAB_ALLOC) {
-			zfs_dbgmsg("%s: metaslab allocation failure, "
+			zfs_dbgmsg("%s: metaslab allocation failure in %s "
-			    "trying fallback: zio %px, size %llu, error %d",
+			    "class, trying fallback to %s class: zio %px, "
-			    spa_name(spa), zio, (u_longlong_t)zio->io_size,
+			    "size %llu, error %d", spa_name(spa),
-			    error);
+			    metaslab_class_get_name(mc),
+			    metaslab_class_get_name(newmc),
+			    zio, (u_longlong_t)zio->io_size, error);
 		}
 		zio->io_metaslab_class = mc = newmc;
 		ZIOSTAT_BUMP(ziostat_alloc_class_fallbacks);