[PATCH v2] block/loop: add documentation for sysfs interface

[Aishwarya Pant]

Documentation has been compiled from git logs and by reading through
code.

Signed-off-by: Aishwarya Pant <aishpant@xxxxxxxxx>
---
For drivers/block/loop.c, I don't see any maintainers or mailing lists except
for LKML. I am guessing linux-block mailing list should be okay.

Changes in v2:
- Add linux-block@xxxxxxxxxxxxxxx to the recipient list.

 Documentation/ABI/testing/sysfs-block-loop | 50 ++++++++++++++++++++++++++++++
 1 file changed, 50 insertions(+)
 create mode 100644 Documentation/ABI/testing/sysfs-block-loop

diff --git a/Documentation/ABI/testing/sysfs-block-loop b/Documentation/ABI/testing/sysfs-block-loop
new file mode 100644
index 000000000000..627f4eb87286
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-block-loop
@@ -0,0 +1,50 @@
+What:		/sys/block/loopX/loop/autoclear
+Date:		Aug, 2010
+KernelVersion:	v2.6.37
+Contact:	linux-block@xxxxxxxxxxxxxxx
+Description:
+		(RO) Shows if the device is in autoclear mode or not ( "1" or
+		"0"). Autoclear (if set) indicates that the loopback device will
+		self-distruct after last close.
+
+What:		/sys/block/loopX/loop/backing_file
+Date:		Aug, 2010
+KernelVersion:	v2.6.37
+Contact:	linux-block@xxxxxxxxxxxxxxx
+Description:
+		(RO) The path of the backing file that the loop device maps its
+		data blocks to.
+
+What:		/sys/block/loopX/loop/offset
+Date:		Aug, 2010
+KernelVersion:	v2.6.37
+Contact:	linux-block@xxxxxxxxxxxxxxx
+Description:
+		(RO) Start offset (in bytes).
+
+What:		/sys/block/loopX/loop/sizelimit
+Date:		Aug, 2010
+KernelVersion:	v2.6.37
+Contact:	linux-block@xxxxxxxxxxxxxxx
+Description:
+		(RO) The size (in bytes) that the block device maps, starting
+		from the offset.
+
+What:		/sys/block/loopX/loop/partscan
+Date:		Aug, 2011
+KernelVersion:	v3.10
+Contact:	linux-block@xxxxxxxxxxxxxxx
+Description:
+		(RO) Shows if automatic partition scanning is enabled for the
+		device or not ("1" or "0"). This can be requested individually
+		per loop device during its setup by setting LO_FLAGS_PARTSCAN in
+		in the ioctl request. By default, no partition tables are
+		scanned.
+
+What:		/sys/block/loopX/loop/dio
+Date:		Aug, 2015
+KernelVersion:	v4.10
+Contact:	linux-block@xxxxxxxxxxxxxxx
+Description:
+		(RO) Shows if direct IO is being used to access backing file or
+		not ("1 or "0").
-- 
2.16.1