From bb351abaf5cd4f9237e1b3094d9cc04853de6d95 Mon Sep 17 00:00:00 2001
From: Weiping Zhang <zhangweiping@didiglobal.com>
Date: Wed, 26 Dec 2018 11:56:33 +0800
Subject: [PATCH] block: add documentation for io_timeout

Add documentation for /sys/block/<disk>/queue/io_timeout.

Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Weiping Zhang <zhangweiping@didiglobal.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
---
 Documentation/ABI/testing/sysfs-block | 9 +++++++++
 Documentation/block/queue-sysfs.txt   | 7 +++++++
 2 files changed, 16 insertions(+)

diff --git a/Documentation/ABI/testing/sysfs-block b/Documentation/ABI/testing/sysfs-block
index 7710d4022b19..dfad7427817c 100644
--- a/Documentation/ABI/testing/sysfs-block
+++ b/Documentation/ABI/testing/sysfs-block
@@ -279,3 +279,12 @@ Description:
 		size in 512B sectors of the zones of the device, with
 		the eventual exception of the last zone of the device
 		which may be smaller.
+
+What:		/sys/block/<disk>/queue/io_timeout
+Date:		November 2018
+Contact:	Weiping Zhang <zhangweiping@didiglobal.com>
+Description:
+		io_timeout is the request timeout in milliseconds. If a request
+		does not complete in this time then the block driver timeout
+		handler is invoked. That timeout handler can decide to retry
+		the request, to fail it or to start a device recovery strategy.
diff --git a/Documentation/block/queue-sysfs.txt b/Documentation/block/queue-sysfs.txt
index 39e286d7afc9..83b457e24bba 100644
--- a/Documentation/block/queue-sysfs.txt
+++ b/Documentation/block/queue-sysfs.txt
@@ -67,6 +67,13 @@ If set to a value larger than 0, the kernel will put the process issuing
 IO to sleep for this amount of microseconds before entering classic
 polling.
 
+io_timeout (RW)
+---------------
+io_timeout is the request timeout in milliseconds. If a request does not
+complete in this time then the block driver timeout handler is invoked.
+That timeout handler can decide to retry the request, to fail it or to start
+a device recovery strategy.
+
 iostats (RW)
 -------------
 This file is used to control (on/off) the iostats accounting of the
-- 
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