[PATCH 4.19 022/421] ext4: correct the cache_nr in tracepoint ext4_es_shrink_exit

From: Greg Kroah-Hartman
Date: Mon Jul 19 2021 - 11:53:27 EST

From: Zhang Yi <yi.zhang@xxxxxxxxxx>

commit 4fb7c70a889ead2e91e184895ac6e5354b759135 upstream.

The cache_cnt parameter of tracepoint ext4_es_shrink_exit means the
remaining cache count after shrink, but now it is the cache count before
shrink, fix it by read sbi->s_extent_cache_cnt again.

Fixes: 1ab6c4997e04 ("fs: convert fs shrinkers to new scan/count API")
Cc: stable@xxxxxxxxxxxxxxx # 3.12+
Signed-off-by: Zhang Yi <yi.zhang@xxxxxxxxxx>
Reviewed-by: Jan Kara <jack@xxxxxxx>
Link: https://lore.kernel.org/r/20210522103045.690103-3-yi.zhang@xxxxxxxxxx
Signed-off-by: Theodore Ts'o <tytso@xxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

fs/ext4/extents_status.c | 1 +
1 file changed, 1 insertion(+)

--- a/fs/ext4/extents_status.c
+++ b/fs/ext4/extents_status.c
@@ -1085,6 +1085,7 @@ static unsigned long ext4_es_scan(struct

nr_shrunk = __es_shrink(sbi, nr_to_scan, NULL);

+ ret = percpu_counter_read_positive(&sbi->s_es_stats.es_stats_shk_cnt);
trace_ext4_es_shrink_scan_exit(sbi->s_sb, nr_shrunk, ret);
return nr_shrunk;