btrfs-progs: Convert man page for btrfs-device subcommand.

Convert man page for btrfs-device subcommand.

Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
Signed-off-by: David Sterba <dsterba@suse.cz>

Documentation/Makefile

@@ -19,7 +19,7 @@ MAN8_TXT += btrfs.txt
 MAN8_TXT += btrfs-subvolume.txt
 MAN8_TXT += btrfs-filesystem.txt
 MAN8_TXT += btrfs-balance.txt
-#MAN8_TXT += btrfs-device.txt
+MAN8_TXT += btrfs-device.txt
 #MAN8_TXT += btrfs-scrub.txt
 #MAN8_TXT += btrfs-check.txt
 #MAN8_TXT += btrfs-rescue.txt

Documentation/btrfs-device.txt

@@ -0,0 +1,75 @@
+btrfs-device(8)
+===============
+
+NAME
+----
+btrfs-device - control btrfs devices
+
+SYNOPSIS
+--------
+'btrfs device' <subcommand> <args>
+
+DESCRIPTION
+-----------
+'btrfs device' is used to control the btrfs devices, since btrfs can be used
+across several devices, 'btrfs device' is used for multiple device management.
+
+SUBCOMMAND
+----------
+'add' [-Kf] <dev> [<dev>...] <path>::
+Add device(s) to the filesystem identified by <path>.
++
+If applicable, a whole device discard (TRIM) operation is performed.
++
+`Options`
++
+-K|--nodiscard::::
+do not perform discard by default
+-f|--force::::
+force overwrite of existing filesystem on the given disk(s)
+
+'delete' <dev> [<dev>...] <path>::
+Remove device(s) from a filesystem identified by <path>.
+
+'scan' [(--all-devices|-d)|<device> [<device>...]]::
+Scan devices for a btrfs filesystem.
++
+If one or more devices are passed, these are scanned for a btrfs filesystem. 
+If no devices are passed, btrfs uses block devices containing btrfs
+filesystem as listed by blkid.
+Finally, if '--all-devices' or '-d' is passed, all the devices under /dev are 
+scanned.
+
+'disk-usage' [-b] <path> [<path>..]::
+Show which chunks are in a device.
++
+If '-b' is given, byte will be set as unit.
+
+'ready' <device>::
+Check device to see if it has all of it's devices in cache for mounting.
+
+'stats' [-z] <path>|<device>::
+Read and print the device IO stats for all devices of the filesystem
+identified by <path> or for a single <device>.
++
+`Options`
++
+-z::::
+Reset stats to zero after reading them.
+
+EXIT STATUS
+-----------
+'btrfs device' returns a zero exist status if it succeeds. Non zero is
+returned in case of failure.
+
+AVAILABILITY
+------------
+'btrfs' is part of btrfs-progs. Btrfs filesystem is currently under heavy
+development,
+and not suitable for any uses other than benchmarking and review.
+Please refer to the btrfs wiki http://btrfs.wiki.kernel.org for
+further details.
+
+SEE ALSO
+--------
+`mkfs.btrfs`(8),