zram: export new 'io_stat' sysfs attrs

Per-device `zram<id>/io_stat' file provides accumulated I/O statistics of
particular zram device in a format similar to block layer statistics.  The
file consists of a single line and represents the following stats
(separated by whitespace):

	failed_reads
	failed_writes
	invalid_io
	notify_free

Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Acked-by: Minchan Kim <minchan@kernel.org>
Cc: Nitin Gupta <ngupta@vflare.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/Documentation/ABI/testing/sysfs-block-zram b/Documentation/ABI/testing/sysfs-block-zram
index 91ad7071b9e848083d7cc00ed00bb6e9e98162ee..a7f622f9bcf6579caa24874bf9062201432e7435 100644 (file)
--- a/Documentation/ABI/testing/sysfs-block-zram
+++ b/Documentation/ABI/testing/sysfs-block-zram
@@ -149,3 +149,12 @@ Description:
                The compact file is write-only and trigger compaction for
                allocator zrm uses. The allocator moves some objects so that
                it could free fragment space.
+
+What:          /sys/block/zram<id>/io_stat
+Date:          August 2015
+Contact:       Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
+Description:
+               The io_stat file is read-only and accumulates device's I/O
+               statistics not accounted by block layer. For example,
+               failed_reads, failed_writes, etc. File format is similar to
+               block layer statistics file format.

diff --git a/Documentation/blockdev/zram.txt b/Documentation/blockdev/zram.txt
index 5d5e8be5cc14f8d83c16bbd7b90a6b41c921fad7..5ed4dd5f589c6064fa2e01afd56626716f6bfa1d 100644 (file)
--- a/Documentation/blockdev/zram.txt
+++ b/Documentation/blockdev/zram.txt
@@ -153,6 +153,18 @@ File /sys/block/zram<id>/stat
 Represents block layer statistics. Read Documentation/block/stat.txt for
 details.
 
+
+File /sys/block/zram<id>/io_stat
+
+The stat file represents device's I/O statistics not accounted by block
+layer and, thus, not available in zram<id>/stat file. It consists of a
+single line of text and contains the following stats separated by
+whitespace:
+       failed_reads
+       failed_writes
+       invalid_io
+       notify_free
+
 9) Deactivate:
        swapoff /dev/zram0
        umount /dev/zram1

diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index 6adccdfd6e078acf09e916a62ceb4ab03b629c7d..99d9286ec2cd68835a71f7f9833df75a9015bae7 100644 (file)
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -384,6 +384,25 @@ static ssize_t compact_store(struct device *dev,
        return len;
 }
 
+static ssize_t io_stat_show(struct device *dev,
+               struct device_attribute *attr, char *buf)
+{
+       struct zram *zram = dev_to_zram(dev);
+       ssize_t ret;
+
+       down_read(&zram->init_lock);
+       ret = scnprintf(buf, PAGE_SIZE,
+                       "%8llu %8llu %8llu %8llu\n",
+                       (u64)atomic64_read(&zram->stats.failed_reads),
+                       (u64)atomic64_read(&zram->stats.failed_writes),
+                       (u64)atomic64_read(&zram->stats.invalid_io),
+                       (u64)atomic64_read(&zram->stats.notify_free));
+       up_read(&zram->init_lock);
+
+       return ret;
+}
+
+static DEVICE_ATTR_RO(io_stat);
 ZRAM_ATTR_RO(num_reads);
 ZRAM_ATTR_RO(num_writes);
 ZRAM_ATTR_RO(failed_reads);
@@ -1085,6 +1104,7 @@ static struct attribute *zram_disk_attrs[] = {
        &dev_attr_mem_used_max.attr,
        &dev_attr_max_comp_streams.attr,
        &dev_attr_comp_algorithm.attr,
+       &dev_attr_io_stat.attr,
        NULL,
 };