ext4 crypto: fix return value for ext4_es_scan()

Theodore Ts'o · Theodore Ts'o · commit 170fc7842b6f · 2015-07-06T17:05:55.000-04:00
Between 3.10 and 3.18, the abstraction to scan for objects in the slab
cache which can be freed when the system is under memory pressure
changed.  When I backported the ext4 code from 3.18 to the 3.10
kernel, I didn't get the return value required by the calling
conventions for the scan function correct, which could potentially
cause the memory reclaimer to loop indefinitely.

Change-Id: I1712fedf96fd91c911fb4d019d7ef76f6c4c1808
Signed-off-by: "Theodore Ts'o" &lt;tytso@google.com&gt;
diff --git a/fs/ext4/extents_status.c b/fs/ext4/extents_status.c
@@ -1077,7 +1077,7 @@ static unsigned long ext4_es_scan(struct shrinker *shrink,
 	nr_shrunk = __ext4_es_shrink(sbi, nr_to_scan, NULL);
 
 	trace_ext4_es_shrink_scan_exit(sbi->s_sb, nr_shrunk, ret);
-	return nr_shrunk;
+	return percpu_counter_read_positive(&sbi->s_es_stats.es_stats_lru_cnt);
 }
 
 static int ext4_es_shrink(struct shrinker *shrink, struct shrink_control *sc)

Original file line number	Diff line number	Diff line change
`@@ -1077,7 +1077,7 @@ static unsigned long ext4_es_scan(struct shrinker *shrink,`
`1077`	`1077`	`nr_shrunk = __ext4_es_shrink(sbi, nr_to_scan, NULL);`
`1078`	`1078`
`1079`	`1079`	`trace_ext4_es_shrink_scan_exit(sbi->s_sb, nr_shrunk, ret);`
`1080`		`- return nr_shrunk;`
	`1080`	`+ return percpu_counter_read_positive(&sbi->s_es_stats.es_stats_lru_cnt);`
`1081`	`1081`	`}`
`1082`	`1082`
`1083`	`1083`	`static int ext4_es_shrink(struct shrinker shrink, struct shrink_control sc)`