Fix zpool iostat bandwidth/ops calculation

print_vdev_stats() subtracts the old bandwidth/ops stats from the new stats
to calculate the bandwidth/ops numbers in "zpool iostat".  However when the
TXG numbers change between stats, zpool_refresh_stats() will incorrectly assign
a NULL to the old stats. This causes print_vdev_stats() to use zeroes for
the old bandwidth/ops numbers, resulting in an inaccurate calculation.

This fix allows the calculation to happen even when TXGs change.

Signed-off-by: Tony Hutter <hutter2@llnl.gov>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #4387

diff --git a/lib/libzfs/libzfs_config.c b/lib/libzfs/libzfs_config.c
index 9857ed9850ffb03d73db1b31846ca62ba4777ba9..849a13051b1eb78c47a6d430067004b78472866c 100644 (file)
--- a/lib/libzfs/libzfs_config.c
+++ b/lib/libzfs/libzfs_config.c
@@ -311,22 +311,10 @@ zpool_refresh_stats(zpool_handle_t *zhp, boolean_t *missing)
        zhp->zpool_config_size = zc.zc_nvlist_dst_size;
 
        if (zhp->zpool_config != NULL) {
-               uint64_t oldtxg, newtxg;
-
-               verify(nvlist_lookup_uint64(zhp->zpool_config,
-                   ZPOOL_CONFIG_POOL_TXG, &oldtxg) == 0);
-               verify(nvlist_lookup_uint64(config,
-                   ZPOOL_CONFIG_POOL_TXG, &newtxg) == 0);
-
                if (zhp->zpool_old_config != NULL)
                        nvlist_free(zhp->zpool_old_config);
 
-               if (oldtxg != newtxg) {
-                       nvlist_free(zhp->zpool_config);
-                       zhp->zpool_old_config = NULL;
-               } else {
-                       zhp->zpool_old_config = zhp->zpool_config;
-               }
+               zhp->zpool_old_config = zhp->zpool_config;
        }
 
        zhp->zpool_config = config;