[Devel] [PATCH RHEL7 COMMIT] ms/ext4: correct the cache_nr in tracepoint ext4_es_shrink_exit

[Konstantin Khorenko]

The commit is pushed to "branch-rh7-3.10.0-1160.119.1.vz7.224.x-ovz" and will appear at https://src.openvz.org/scm/ovz/vzkernel.git
after rh7-3.10.0-1160.119.1.el7
------>
commit 04bf22b02ad7e1bc16fee332694bc21daea4d50d
Author: Zhang Yi <yi.zhang at huawei.com>
Date:   Sat May 22 18:30:45 2021 +0800

    ms/ext4: correct the cache_nr in tracepoint ext4_es_shrink_exit
    
    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.
    
    mFixes: 1ab6c4997e04 ("fs: convert fs shrinkers to new scan/count API")
    Cc: stable at vger.kernel.org # 3.12+
    Signed-off-by: Zhang Yi <yi.zhang at huawei.com>
    Reviewed-by: Jan Kara <jack at suse.cz>
    Link: https://lore.kernel.org/r/20210522103045.690103-3-yi.zhang@huawei.com
    Signed-off-by: Theodore Ts'o <tytso at mit.edu>
    
    Ported in the scope of
    https://virtuozzo.atlassian.net/browse/PSBM-157196
    
    (cherry picked from commit 4fb7c70a889ead2e91e184895ac6e5354b759135)
    Signed-off-by: Konstantin Khorenko <khorenko at virtuozzo.com>
---
 fs/ext4/extents_status.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/fs/ext4/extents_status.c b/fs/ext4/extents_status.c
index d78546e86d8c..acfc773b7d97 100644
--- a/fs/ext4/extents_status.c
+++ b/fs/ext4/extents_status.c
@@ -1068,6 +1068,7 @@ static unsigned long ext4_es_scan(struct shrinker *shrink,
 
 	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;
 }