zram: propagate error to user
When we initialized zcomp with single, we couldn't change
max_comp_streams without zram reset but current interface doesn't show
any error to user and even it changes max_comp_streams's value without
any effect so it would make user very confusing.
This patch prevents max_comp_streams's change when zcomp was initialized
as single zcomp and emit the error to user(ex, echo).
[akpm@linux-foundation.org: don't return with the lock held, per Sergey]
[fengguang.wu@intel.com: fix coccinelle warnings]
Signed-off-by: Minchan Kim <minchan@kernel.org>
Cc: Nitin Gupta <ngupta@vflare.org>
Cc: Jerome Marchand <jmarchan@redhat.com>
Acked-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Signed-off-by: Fengguang Wu <fengguang.wu@intel.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index 6b462d2..80a1cfc 100644
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -127,19 +127,28 @@
{
int num;
struct zram *zram = dev_to_zram(dev);
+ int ret;
- if (kstrtoint(buf, 0, &num))
- return -EINVAL;
+ ret = kstrtoint(buf, 0, &num);
+ if (ret < 0)
+ return ret;
if (num < 1)
return -EINVAL;
+
down_write(&zram->init_lock);
if (init_done(zram)) {
- if (zcomp_set_max_streams(zram->comp, num))
+ if (!zcomp_set_max_streams(zram->comp, num)) {
pr_info("Cannot change max compression streams\n");
+ ret = -EINVAL;
+ goto out;
+ }
}
+
zram->max_comp_streams = num;
+ ret = len;
+out:
up_write(&zram->init_lock);
- return len;
+ return ret;
}
static ssize_t comp_algorithm_show(struct device *dev,