Hi, 在 2023/12/22 10:34, 20 39 写道:
Hi Kuai, Thank you for your patience. This email is essentially the same as my previous one, only now adjusted to plain text format. I apologize for any inconvenience caused earlier. Thanks for your email and the insightful points you've raised. Let me clarify a few aspects regarding the raid5_cache_count() and raid5_set_cache_size() functions. 1. Callback Function in setup_conf(): You mentioned that raid5_cache_count() is called from setup_conf() where reconfig_mutex is held. While this is true, it's important to note that raid5_cache_count() is actually initialized as a callback function in setup_conf(), as described in /include/linux/shrinker.h. This means it could be invoked later in a context where the reconfig_mutex isn't necessarily held. The documentation in shrinker.h indicates potential invocation scenarios beyond the initial setup context.
Yes, you're right. I misread the code. Then this patch looks good to me, just one nit below.
@@ -7390,11 +7390,12 @@ static unsigned long raid5_cache_count(struct shrinker *shrink, struct shrink_control *sc) { struct r5conf *conf = shrink->private_data; - - if (conf->max_nr_stripes < conf->min_nr_stripes) + int max_stripes = conf->max_nr_stripes; + int min_stripes = conf->min_nr_stripes;
Since read and write can concurrent, I'll suggest to use READ_ONCE() and WRITE_ONCE() for max/min_nr_stripes. Thanks, Kuai
+ if (max_stripes < min_stripes) /* unlikely, but not impossible */ return 0; - return conf->max_nr_stripes - conf->min_nr_stripes; + return max_stripes - min_stripes; } static struct r5conf *setup_conf(struct mddev *mddev).
