Report ashift of L2ARC devices in zdb

Commit 8af1104 does not actually store the ashift of cache devices in their label. However, in order to facilitate reporting the ashift through zdb, we enable this in the present commit. We also document how the retrieval of the ashift is done. Reviewed-by: Brian Behlendorf <[email protected]> Signed-off-by: George Amanakis <[email protected]> Closes openzfs#15331
gamanakis · Dec 20, 2023 · 11c86dc · 11c86dc
1 parent 74da5eb
commit 11c86dc
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Showing 2 changed files with 11 additions and 1 deletion.
diff --git a/cmd/zdb/zdb.c b/cmd/zdb/zdb.c
@@ -4815,7 +4815,7 @@ dump_label(const char *dev)
 			if (nvlist_size(config, &size, NV_ENCODE_XDR) != 0)
 				size = buflen;
 
-			/* If the device is a cache device clear the header. */
+			/* If the device is a cache device read the header. */
 			if (!read_l2arc_header) {
 				if (nvlist_lookup_uint64(config,
 				    ZPOOL_CONFIG_POOL_STATE, &l2cache) == 0 &&

diff --git a/module/zfs/vdev_label.c b/module/zfs/vdev_label.c
@@ -1103,6 +1103,16 @@ vdev_label_init(vdev_t *vd, uint64_t crtxg, vdev_labeltype_t reason)
 		    POOL_STATE_L2CACHE) == 0);
 		VERIFY(nvlist_add_uint64(label, ZPOOL_CONFIG_GUID,
 		    vd->vdev_guid) == 0);
+
+		/*
+		 * This is merely to facilitate reporting the ashift of the
+		 * cache device through zdb. The actual retrieval of the
+		 * ashift (in vdev_alloc()) uses the nvlist
+		 * spa->spa_l2cache->sav_config (populated in
+		 * spa_ld_open_aux_vdevs()).
+		 */
+		VERIFY(nvlist_add_uint64(label, ZPOOL_CONFIG_ASHIFT,
+		    vd->vdev_ashift) == 0);
 	} else {
 		uint64_t txg = 0ULL;