zram: report failed read and write stats

zram accounted but did not report numbers of failed read and write
queries.  make these stats available as failed_reads and failed_writes
attrs.

Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Acked-by: Minchan Kim <minchan@kernel.org>
Acked-by: Jerome Marchand <jmarchan@redhat.com>
Cc: Nitin Gupta <ngupta@vflare.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
(cherry picked from commit 6444724939db5de7390c90f7b4a657159b3b4465)
Signed-off-by: Alex Shi <alex.shi@linaro.org>

diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index c4179fb54fde6e09481476bbffd427699556f6f6..4043e783e50ac9ccb8e5b96898ed4c3e8b3ed822 100644 (file)
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -728,6 +728,8 @@ static DEVICE_ATTR(mem_used_total, S_IRUGO, mem_used_total_show, NULL);
 
 ZRAM_ATTR_RO(num_reads);
 ZRAM_ATTR_RO(num_writes);
+ZRAM_ATTR_RO(failed_reads);
+ZRAM_ATTR_RO(failed_writes);
 ZRAM_ATTR_RO(invalid_io);
 ZRAM_ATTR_RO(notify_free);
 ZRAM_ATTR_RO(zero_pages);
@@ -739,6 +741,8 @@ static struct attribute *zram_disk_attrs[] = {
        &dev_attr_reset.attr,
        &dev_attr_num_reads.attr,
        &dev_attr_num_writes.attr,
+       &dev_attr_failed_reads.attr,
+       &dev_attr_failed_writes.attr,
        &dev_attr_invalid_io.attr,
        &dev_attr_notify_free.attr,
        &dev_attr_zero_pages.attr,