zram: document failed_reads, failed_writes stats

Document `failed_reads' and `failed_writes' device attributes.
Remove info about `discard' - there is no such zram attr.

Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: 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>

2 files changed, 17 insertions, 10 deletions

diff --git a/Documentation/ABI/testing/sysfs-block-zram b/Documentation/ABI/testing/sysfs-block-zram
index 3f0b9ae61d8c..8aa046841625 100644
--- a/Documentation/ABI/testing/sysfs-block-zram
+++ b/Documentation/ABI/testing/sysfs-block-zram
@@ -43,6 +43,21 @@ Description:
                 The invalid_io file is read-only and specifies the number of
                 non-page-size-aligned I/O requests issued to this device.
 
+What:           /sys/block/zram<id>/failed_reads
+Date:           February 2014
+Contact:        Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
+Description:
+                The failed_reads file is read-only and specifies the number of
+                failed reads happened on this device.
+
+
+What:           /sys/block/zram<id>/failed_writes
+Date:           February 2014
+Contact:        Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
+Description:
+                The failed_writes file is read-only and specifies the number of
+                failed writes happened on this device.
+
 What:           /sys/block/zram<id>/notify_free
 Date:           August 2010
 Contact:        Nitin Gupta <ngupta@vflare.org>
@@ -53,15 +68,6 @@ Description:
                 is freed. This statistic is applicable only when this disk is
                 being used as a swap disk.
 
-What:           /sys/block/zram<id>/discard
-Date:           August 2010
-Contact:        Nitin Gupta <ngupta@vflare.org>
-Description:
-                The discard file is read-only and specifies the number of
-                discard requests received by this device. These requests
-                provide information to block device regarding blocks which are
-                no longer used by filesystem.
-
 What:           /sys/block/zram<id>/zero_pages
 Date:           August 2010
 Contact:        Nitin Gupta <ngupta@vflare.org>
diff --git a/Documentation/blockdev/zram.txt b/Documentation/blockdev/zram.txt
index 393541be1ec0..b31ac5e5d4b9 100644
--- a/Documentation/blockdev/zram.txt
+++ b/Documentation/blockdev/zram.txt
@@ -51,9 +51,10 @@ size of the disk when not in use so a huge zram is wasteful.
                 disksize
                 num_reads
                 num_writes
+                failed_reads
+                failed_writes
                 invalid_io
                 notify_free
-                discard
                 zero_pages
                 orig_data_size
                 compr_data_size