ext4: remove check for zero nr_to_scan in ext4_es_scan()

After converting fs shrinkers to new scan/count API, we are no longer
pass zero nr_to_scan parameter to detect the number of objects to free,
just remove this check.

Fixes: 1ab6c499 ("fs: convert fs shrinkers to new scan/count API")
Cc: stable@vger.kernel.org # 3.12+
Signed-off-by: Zhang Yi <yi.zhang@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20210522103045.690103-2-yi.zhang@huawei.comSigned-off-by: Theodore Ts'o <tytso@mit.edu>

fs/ext4/extents_status.c

@@ -1574,9 +1574,6 @@ static unsigned long ext4_es_scan(struct shrinker *shrink,
 	ret = percpu_counter_read_positive(&sbi->s_es_stats.es_stats_shk_cnt);
 	trace_ext4_es_shrink_scan_enter(sbi->s_sb, nr_to_scan, ret);
 
-	if (!nr_to_scan)
-		return ret;
-
 	nr_shrunk = __es_shrink(sbi, nr_to_scan, NULL);
 
 	trace_ext4_es_shrink_scan_exit(sbi->s_sb, nr_shrunk, ret);