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Subject: [PATCH 4/6] Update the makefile for generating the man page.
To: linux-btrfs <linux-btrfs@vger.kernel.org>
From: Goffredo Baroncelli <kreijack@libero.it>
Date: Tue, 19 Jul 2011 18:12:16 +0200
Message-ID: <20110719161216.3210.76829.stgit@venice.bhome>
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From: Goffredo Baroncelli <kreijack@inwind.it>

The makefile is update in order to generate the man/btrfs.8.in by the
helpextract tool on the basis of the sources comments. The old man page
is renamed as btrfs.8.in.old.
---
 Makefile           |   11 +-
 man/btrfs.8.in     |  359 ----------------------------------------------------
 man/btrfs.8.in.old |  359 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 369 insertions(+), 360 deletions(-)
 delete mode 100644 man/btrfs.8.in
 create mode 100644 man/btrfs.8.in.old


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diff --git a/Makefile b/Makefile
index edee1a0..dc1342f 100644
--- a/Makefile
+++ b/Makefile
@@ -18,6 +18,8 @@ LIBS = -luuid
 progs = btrfsctl mkfs.btrfs btrfs-debug-tree btrfs-show btrfs-vol btrfsck \
 	btrfs btrfs-map-logical
 
+btrfs_man_page_source = btrfs.c btrfs_cmds.c scrub.c
+
 # make C=1 to enable sparse
 ifdef C
 	check = sparse $(CHECKFLAGS)
@@ -84,13 +86,20 @@ convert: $(objects) convert.o
 ioctl-test: $(objects) ioctl-test.o
 	$(CC) $(CFLAGS) -o ioctl-test $(objects) ioctl-test.o $(LDFLAGS) $(LIBS)
 
-manpages:
+helpextract: helpextract.o
+	$(CC) $(CFLAGS) -o $@ helpextract.o
+
+man/btrfs.8.in: helpextract $(btrfs_man_page_source)
+	./helpextract --man-page $(btrfs_man_page_source) >$@
+
+manpages: man/btrfs.8.in
 	cd man; make
 
 install-man:
 	cd man; make install
 
 clean :
+	rm -f man/btrfs.8.in
 	rm -f $(progs) cscope.out *.o .*.d btrfs-convert btrfs-image btrfs-select-super \
 	      btrfs-zero-log btrfstune dir-test ioctl-test quick-test version.h
 	cd man; make clean
diff --git a/man/btrfs.8.in b/man/btrfs.8.in
deleted file mode 100644
index 84a60cd..0000000
--- a/man/btrfs.8.in
+++ /dev/null
@@ -1,359 +0,0 @@
-.TH BTRFS 8 "" "btrfs" "btrfs"
-.\"
-.\" Man page written by Goffredo Baroncelli <kreijack@inwind.it> (Feb 2010)
-.\"
-.SH NAME
-btrfs \- control a btrfs filesystem
-.SH SYNOPSIS
-\fBbtrfs\fP \fBsubvolume snapshot\fP\fI [-r] <source> [<dest>/]<name>\fP
-.PP
-\fBbtrfs\fP \fBsubvolume delete\fP\fI <subvolume>\fP
-.PP
-\fBbtrfs\fP \fBsubvolume create\fP\fI [<dest>/]<name>\fP
-.PP
-\fBbtrfs\fP \fBsubvolume list\fP\fI [-p] <path>\fP
-.PP
-\fBbtrfs\fP \fBsubvolume set-default\fP\fI <id> <path>\fP
-.PP
-\fBbtrfs\fP \fBfilesystem sync\fP\fI <path> \fP
-.PP
-\fBbtrfs\fP \fBfilesystem resize\fP\fI [+/\-]<size>[gkm]|max <filesystem>\fP
-.PP
-\fBbtrfs\fP \fBfilesystem label\fP\fI <dev> [newlabel]\fP
-.PP
-\fBbtrfs\fP \fBfilesystem defrag\fP\fI [options] <file>|<dir> [<file>|<dir>...]\fP
-.PP
-\fBbtrfs\fP \fBsubvolume find-new\fP\fI <subvolume> <last_gen>\fP
-.PP
-\fBbtrfs\fP \fBfilesystem balance\fP [\fB-wcv\fP] [\fB--wait\fP] [\fB--count\fP] [\fB--verbose\fP] [\fB-f\fP|\fBfilter=\fP\fI<filter>\fP] \fI<path>\fP
-.PP
-\fBbtrfs\fP \fBbalance start\fP [\fB-wcv\fP] [\fB--wait\fP] [\fB--count\fP] [\fB--verbose\fP] [\fB-f\fP|\fBfilter=\fP\fI<filter>\fP] \fI<path>\fP
-.PP
-\fBbtrfs\fP \fBbalance progress\fP [\fB-m\fP|\fB--monitor\fP] \fI<path>\fP
-.PP
-\fBbtrfs\fP \fBbalance cancel\fP \fI<path>\fP
-.PP
-\fBbtrfs\fP \fBfilesystem defragment\fP\fI <file>|<dir> [<file>|<dir>...]\fP
-.PP
-\fBbtrfs\fP \fBdevice scan\fP\fI [--all-devices|<device> [<device>...]]\fP
-.PP
-\fBbtrfs\fP \fBdevice show\fP\fI [--all-devices|<uuid>|<label>]\fP
-.PP
-\fBbtrfs\fP \fBdevice add\fP\fI <device> [<device>...] <path> \fP
-.PP
-\fBbtrfs\fP \fBdevice delete\fP\fI <device> [<device>...] <path> \fP
-.PP
-\fBbtrfs\fP \fBscrub start\fP [-Bdqru] {\fI<path>\fP|\fI<device>\fP}
-.PP
-\fBbtrfs\fP \fBscrub cancel\fP {\fI<path>\fP|\fI<device>\fP}
-.PP
-\fBbtrfs\fP \fBscrub resume\fP [-Bdqru] {\fI<path>\fP|\fI<device>\fP}
-.PP
-\fBbtrfs\fP \fBscrub status\fP [-d] {\fI<path>\fP|\fI<device>\fP}
-.PP
-\fBbtrfs\fP \fBhelp|\-\-help|\-h \fP\fI\fP
-.PP
-\fBbtrfs\fP \fB<command> \-\-help \fP\fI\fP
-.PP
-.SH DESCRIPTION
-.B btrfs
-is used to control the filesystem and the files and directories stored. It is
-the tool to create or destroy a snapshot or a subvolume for the
-filesystem, to defrag a file or a directory, flush the data to the disk,
-to resize the filesystem, to scan the device.
-
-It is possible to abbreviate the commands unless the commands  are ambiguous.
-For example: it is possible to run
-.I btrfs sub snaps
-instead of
-.I btrfs subvolume snapshot.
-But
-.I btrfs file s
-is not allowed, because
-.I file s
-may be interpreted both as
-.I filesystem show
-and as
-.I filesystem sync.
-In this case
-.I btrfs
-returnsfilesystem sync
-If a command is terminated by
-.I --help
-, the detailed help is showed. If the passed command matches more commands,
-detailed help of all the matched commands is showed. For example
-.I btrfs dev --help
-shows the help of all
-.I device*
-commands.
-
-.SH COMMANDS
-.TP
-
-\fBsubvolume snapshot\fR\fI [-r] <source> [<dest>/]<name>\fR
-Create a writable/readonly snapshot of the subvolume \fI<source>\fR with the
-name \fI<name>\fR in the \fI<dest>\fR directory. If \fI<source>\fR is not a
-subvolume, \fBbtrfs\fR returns an error. If \fI-r\fR is given, the snapshot
-will be readonly.
-.TP
-
-\fBsubvolume delete\fR\fI <subvolume>\fR
-Delete the subvolume \fI<subvolume>\fR. If \fI<subvolume>\fR is not a
-subvolume, \fBbtrfs\fR returns an error.
-.TP
-
-\fBsubvolume create\fR\fI [<dest>/]<name>\fR
-Create a subvolume in \fI<dest>\fR (or in the current directory if
-\fI<dest>\fR is omitted).
-.TP
-
-\fBsubvolume list\fR\fI [-p] <path>\fR
-List the subvolumes present in the filesystem \fI<path>\fR. For every
-subvolume the following information is shown by default.
-ID <ID> top level <ID> path <path>
-where path is the relative path of the subvolume to the \fItop level\fR
-subvolume.
-The subvolume's ID may be used by the \fBsubvolume set-default\fR command, or
-at mount time via the \fIsubvol=\fR option.
-If \fI-p\fR is given, then \fIparent <ID>\fR is added to the output between ID
-and top level. The parent's ID may be used at mount time via the
-\fIsubvolrootid=\fR option.
-.TP
-
-\fBsubvolume set-default\fR\fI <id> <path>\fR
-Set the subvolume of the filesystem \fI<path>\fR which is mounted as 
-\fIdefault\fR. The subvolume is identified by \fI<id>\fR, which 
-is returned by the \fBsubvolume list\fR command.
-.TP
-
-\fBfilesystem defragment\fP -c[zlib|lzo] [-l \fIlen\fR] [-s \fIstart\fR] [-t \fIsize\fR] -[vf] <\fIfile\fR>|<\fIdir\fR> [<\fIfile\fR>|<\fIdir\fR>...]
-
-Defragment file data and/or directory metadata. To defragment all files in a
-directory you have to specify each one on its own or use your shell wildcards.
-
-The start position and the number of bytes to deframention can be specified by \fIstart\fR and \fIlen\fR. Any extent bigger than \fIthresh\fR will be considered already defragged. Use 0 to take the kernel default, and use 1 to say eveery single extent must be rewritten. You can also turn on compression in defragment operations.
-
-\fB-v\fP be verbose
-
-\fB-c\fP compress file contents while defragmenting
-
-\fB-f\fP flush filesystem after defragmenting
-
-\fB-s start\fP defragment only from byte \fIstart\fR onward
-
-\fB-l len\fP defragment only up to \fIlen\fR bytes
-
-\fB-t size\fP defragment only files at least \fIsize\fR bytes big
-
-NOTE: defragmenting with kernels up to 2.6.37 will unlink COW-ed copies of data, don't 
-use it if you use snapshots, have de-duplicated your data or made copies with 
-\fBcp --reflink\fP.
-\fBsubvolume find-new\fR\fI <subvolume> <last_gen>\fR
-List the recently modified files in a subvolume, after \fI<last_gen>\fR ID.
-.TP
-
-\fBfilesystem sync\fR\fI <path> \fR
-Force a sync for the filesystem identified by \fI<path>\fR.
-.TP
-
-.\"
-.\" Some wording are extracted by the resize2fs man page
-.\"
-
-\fBfilesystem resize\fR\fI [+/\-]<size>[gkm]|max <path>\fR
-Resize a filesystem identified by \fI<path>\fR.
-The \fI<size>\fR parameter specifies the new size of the filesystem.
-If the prefix \fI+\fR or \fI\-\fR is present the size is increased or decreased
-by the quantity \fI<size>\fR.
-If no units are specified, the unit of the \fI<size>\fR parameter defaults to
-bytes. Optionally, the size parameter may be suffixed by one of the following
-the units designators: 'K', 'M', or 'G', kilobytes, megabytes, or gigabytes,
-respectively.
-
-If 'max' is passed, the filesystem will occupy all available space on the
-volume(s).
-
-The \fBresize\fR command \fBdoes not\fR manipulate the size of underlying
-partition.  If you wish to enlarge/reduce a filesystem, you must make sure you
-can expand the partition before enlarging the filesystem and shrink the
-partition after reducing the size of the filesystem.
-.TP
-
-\fBbtrfs\fP \fBfilesystem label\fP\fI <dev> [newlabel]\fP
-Show or update the label of a filesystem. \fI<dev>\fR is used to identify the
-filesystem. 
-If a \fInewlabel\fR optional argument is passed, the label is changed. The
-following costraints exist for a label:
-.IP
-- the maximum allowable lenght shall be less or equal than 256 chars
-.IP
-- the label shall not  contain the '/' or '\\' characters.
-
-NOTE: Currently there are the following limitations:
-.IP
-- the filesystem has to be unmounted
-.IP
-- the filesystem should not have more than one device.
-.TP
-
-\fBfilesystem show\fR [--all-devices|<uuid>|<label>]\fR
-Show the btrfs filesystem with some additional info. If no \fIUUID\fP or 
-\fIlabel\fP is passed, \fBbtrfs\fR show info of all the btrfs filesystem.
-If \fB--all-devices\fP is passed, all the devices under /dev are scanned;
-otherwise the devices list is extracted from the /proc/partitions file.
-.TP
-
-\fBdevice balance\fP [\fB-wcv\fP] [\fB--wait\fP] [\fB--count\fP] [\fB--verbose\fP] [\fB-f\fP|\fBfilter=\fP\fI<filter>\fP] \fI<path>\fP
-.TP
-\fBbalance start\fR [\fB-wcv\fP] [\fB--wait\fP] [\fB--count\fP] [\fB--verbose\fP] [\fB-f\fP|\fBfilter=\fP\fI<filter>\fP] \fI<path>\fP
-
-Balance the chunks of the filesystem identified by \fI<path>\fR across
-the devices. The command returns immediately, and the balance
-operation runs in the background. Use \fB--wait\fP to run
-synchronously instead. Use \fB--count\fP to scan the filesystem and
-report the number of chunks that would be processed. Use
-\fB--verbose\fP in synchronous mode to report the number of chunks
-examined and balanced. See \fBBALANCE FILTERS\fR, below, for details
-of the different filter types and syntax.
-.TP
-
-\fBdevice add\fR\fI <dev> [<dev>..] <path>\fR
-Add device(s) to the filesystem identified by \fI<path>\fR.
-.TP
-
-\fBdevice delete\fR\fI <dev> [<dev>..] <path>\fR
-Remove device(s) from a filesystem identified by \fI<path>\fR.
-.TP
-
-\fBdevice scan\fR \fI[--all-devices|<device> [<device>...]\fR
-If one or more devices are passed, these are scanned for a btrfs filesystem. 
-If no devices are passed, \fBbtrfs\fR scans all the block devices listed
-in the /proc/partitions file.
-Finally, if \fB--all-devices\fP is passed, all the devices under /dev are 
-scanned.
-.TP
-
-\fBscrub start\fP [-Bdqru] {\fI<path>\fP|\fI<device>\fP}
-Start a scrub on all devices of the filesystem identified by \fI<path>\fR or on
-a single \fI<device>\fR. Without options, scrub is started as a background
-process. Progress can be obtained with the \fBscrub status\fR command. Scrubbing
-involves reading all data from all disks and verifying checksums. Errors are
-corrected along the way if possible.
-.RS
-
-\fIOptions\fR
-.IP -B 5
-Do not background and print scrub statistics when finished.
-.IP -d 5
-Print separate statistics for each device of the filesystem (-B only).
-.IP -q 5
-Quiet. Omit error messages and statistics.
-.IP -r 5
-Read only mode. Do not attempt to correct anything.
-.IP -u 5
-Scrub unused space as well. (NOT IMPLEMENTED)
-.RE
-.TP
-
-\fBscrub cancel\fP {\fI<path>\fP|\fI<device>\fP}
-If a scrub is running on the filesystem identified by \fI<path>\fR, cancel it.
-Progress is saved in the scrub progress file and scrubbing can be resumed later
-using the \fBscrub resume\fR command.
-If a \fI<device>\fR is given, the corresponding filesystem is found and
-\fBscrub cancel\fP behaves as if it was called on that filesystem.
-.TP
-
-\fBscrub resume\fP [-Bdqru] {\fI<path>\fP|\fI<device>\fP}
-Resume a canceled or interrupted scrub cycle on the filesystem identified by
-\fI<path>\fR or on a given \fI<device>\fR. Does not start a new scrub if the
-last scrub finished successfully.
-.RS
-
-\fIOptions\fR
-.TP
-see \fBscrub start\fP.
-.RE
-.TP
-
-\fBscrub status\fP [-d] {\fI<path>\fP|\fI<device>\fP}
-Show status of a running scrub for the filesystem identified by \fI<path>\fR or
-for the specified \fI<device>\fR.
-If no scrub is running, show statistics of the last finished or canceled scrub
-for that filesystem or device.
-.RS
-
-\fIOptions\fR
-.IP -d 5
-Print separate statistics for each device of the filesystem.
-.RE
-
-.PP
-
-\fBbalance progress\fP [\fB-m\fP|\fB--monitor\fP] \fI<path>\fP
-Report progress on the currently-running balance operation on the
-filesystem mounted at \fI<path>\fP. Use --monitor to report progress
-continually, including an estimate of completion time.
-
-\fBbalance cancel\fP \fI<path>\fP
-Cancel the balance currently running on the filesystem mounted at
-\fI<path>\fP.
-
-.SH BALANCE FILTERS
-With balance filters, it is possible to perform a balance operation on
-only a subset of the available chunks. Filters are specified with the
-\fB--filter\fR option of \fBbtrfs device balance\fR or \fBbtrfs
-balance start\fR. Multiple filters may be given, either with multiple
-\fB--filter\fR options, or in a colon-separated list. When multiple
-filters are given, only the chunks meeting all of the selection
-critera are balanced. Help on the avaialble filters can be obtained
-with \fB--filter=help\fR.
-
-.TP
-\fBtype\fR=[\fB~\fR]\fI<flagname>\fR[\fB,\fR...]
-
-Select only the chunks with the given type flag(s). Requiring a flag
-to be off can be specified with a \fB~\fR preceding the flag
-name. Flag names are:
-
-\fBmeta\fR, \fBdata\fR, \fBsys\fR for metadata, file data and system
-chunk types.
-
-\fBraid0\fR, \fBraid1\fR, \fBraid10\fR, \fBdup\fR for chunks of the
-given replication levels.
-
-.TP
-\fBdevid\fR=\fI<n>\fR
-
-Select chunks which have data on device ID \fI<n>\fR. This can be
-used, for example, to reduplicate data in a mirrored configuration
-where one drive has been lost due to hardware failure.
-
-.TP
-\fBvrange\fR=\fI<start>\fB,\fI<end>\fR
-
-Select chunks which have btrfs-internal virtual addresses within the
-range \fI<start>\fR (inclusive) to \fI<end>\fR (exclusive). Given the
-address of the last chunk moved, this filter can be used to restart a
-cancelled or interrupted balance operation, by supplying a range of
-\fB0,\fI<chunkaddr+1>\fR.
-
-.TP
-\fBdrange\fR=\fI<start>\fB,\fI<end>\fR
-
-Select chunks which contain data in the address range \fI<start>\fR
-(inclusive) to \fI<end>\fR (exclusive) on \fIany\fR block device in
-the filesystem. Can be mixed with the \fBdevid\fR filter to select
-chunks in a given address range on a specific device.
-
-.SH EXIT STATUS
-\fBbtrfs\fR returns a zero exist status if it succeeds. Non zero is returned in
-case of failure.
-
-.SH AVAILABILITY
-.B 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.
-.SH SEE ALSO
-.BR mkfs.btrfs (8)
diff --git a/man/btrfs.8.in.old b/man/btrfs.8.in.old
new file mode 100644
index 0000000..84a60cd
--- /dev/null
+++ b/man/btrfs.8.in.old
@@ -0,0 +1,359 @@
+.TH BTRFS 8 "" "btrfs" "btrfs"
+.\"
+.\" Man page written by Goffredo Baroncelli <kreijack@inwind.it> (Feb 2010)
+.\"
+.SH NAME
+btrfs \- control a btrfs filesystem
+.SH SYNOPSIS
+\fBbtrfs\fP \fBsubvolume snapshot\fP\fI [-r] <source> [<dest>/]<name>\fP
+.PP
+\fBbtrfs\fP \fBsubvolume delete\fP\fI <subvolume>\fP
+.PP
+\fBbtrfs\fP \fBsubvolume create\fP\fI [<dest>/]<name>\fP
+.PP
+\fBbtrfs\fP \fBsubvolume list\fP\fI [-p] <path>\fP
+.PP
+\fBbtrfs\fP \fBsubvolume set-default\fP\fI <id> <path>\fP
+.PP
+\fBbtrfs\fP \fBfilesystem sync\fP\fI <path> \fP
+.PP
+\fBbtrfs\fP \fBfilesystem resize\fP\fI [+/\-]<size>[gkm]|max <filesystem>\fP
+.PP
+\fBbtrfs\fP \fBfilesystem label\fP\fI <dev> [newlabel]\fP
+.PP
+\fBbtrfs\fP \fBfilesystem defrag\fP\fI [options] <file>|<dir> [<file>|<dir>...]\fP
+.PP
+\fBbtrfs\fP \fBsubvolume find-new\fP\fI <subvolume> <last_gen>\fP
+.PP
+\fBbtrfs\fP \fBfilesystem balance\fP [\fB-wcv\fP] [\fB--wait\fP] [\fB--count\fP] [\fB--verbose\fP] [\fB-f\fP|\fBfilter=\fP\fI<filter>\fP] \fI<path>\fP
+.PP
+\fBbtrfs\fP \fBbalance start\fP [\fB-wcv\fP] [\fB--wait\fP] [\fB--count\fP] [\fB--verbose\fP] [\fB-f\fP|\fBfilter=\fP\fI<filter>\fP] \fI<path>\fP
+.PP
+\fBbtrfs\fP \fBbalance progress\fP [\fB-m\fP|\fB--monitor\fP] \fI<path>\fP
+.PP
+\fBbtrfs\fP \fBbalance cancel\fP \fI<path>\fP
+.PP
+\fBbtrfs\fP \fBfilesystem defragment\fP\fI <file>|<dir> [<file>|<dir>...]\fP
+.PP
+\fBbtrfs\fP \fBdevice scan\fP\fI [--all-devices|<device> [<device>...]]\fP
+.PP
+\fBbtrfs\fP \fBdevice show\fP\fI [--all-devices|<uuid>|<label>]\fP
+.PP
+\fBbtrfs\fP \fBdevice add\fP\fI <device> [<device>...] <path> \fP
+.PP
+\fBbtrfs\fP \fBdevice delete\fP\fI <device> [<device>...] <path> \fP
+.PP
+\fBbtrfs\fP \fBscrub start\fP [-Bdqru] {\fI<path>\fP|\fI<device>\fP}
+.PP
+\fBbtrfs\fP \fBscrub cancel\fP {\fI<path>\fP|\fI<device>\fP}
+.PP
+\fBbtrfs\fP \fBscrub resume\fP [-Bdqru] {\fI<path>\fP|\fI<device>\fP}
+.PP
+\fBbtrfs\fP \fBscrub status\fP [-d] {\fI<path>\fP|\fI<device>\fP}
+.PP
+\fBbtrfs\fP \fBhelp|\-\-help|\-h \fP\fI\fP
+.PP
+\fBbtrfs\fP \fB<command> \-\-help \fP\fI\fP
+.PP
+.SH DESCRIPTION
+.B btrfs
+is used to control the filesystem and the files and directories stored. It is
+the tool to create or destroy a snapshot or a subvolume for the
+filesystem, to defrag a file or a directory, flush the data to the disk,
+to resize the filesystem, to scan the device.
+
+It is possible to abbreviate the commands unless the commands  are ambiguous.
+For example: it is possible to run
+.I btrfs sub snaps
+instead of
+.I btrfs subvolume snapshot.
+But
+.I btrfs file s
+is not allowed, because
+.I file s
+may be interpreted both as
+.I filesystem show
+and as
+.I filesystem sync.
+In this case
+.I btrfs
+returnsfilesystem sync
+If a command is terminated by
+.I --help
+, the detailed help is showed. If the passed command matches more commands,
+detailed help of all the matched commands is showed. For example
+.I btrfs dev --help
+shows the help of all
+.I device*
+commands.
+
+.SH COMMANDS
+.TP
+
+\fBsubvolume snapshot\fR\fI [-r] <source> [<dest>/]<name>\fR
+Create a writable/readonly snapshot of the subvolume \fI<source>\fR with the
+name \fI<name>\fR in the \fI<dest>\fR directory. If \fI<source>\fR is not a
+subvolume, \fBbtrfs\fR returns an error. If \fI-r\fR is given, the snapshot
+will be readonly.
+.TP
+
+\fBsubvolume delete\fR\fI <subvolume>\fR
+Delete the subvolume \fI<subvolume>\fR. If \fI<subvolume>\fR is not a
+subvolume, \fBbtrfs\fR returns an error.
+.TP
+
+\fBsubvolume create\fR\fI [<dest>/]<name>\fR
+Create a subvolume in \fI<dest>\fR (or in the current directory if
+\fI<dest>\fR is omitted).
+.TP
+
+\fBsubvolume list\fR\fI [-p] <path>\fR
+List the subvolumes present in the filesystem \fI<path>\fR. For every
+subvolume the following information is shown by default.
+ID <ID> top level <ID> path <path>
+where path is the relative path of the subvolume to the \fItop level\fR
+subvolume.
+The subvolume's ID may be used by the \fBsubvolume set-default\fR command, or
+at mount time via the \fIsubvol=\fR option.
+If \fI-p\fR is given, then \fIparent <ID>\fR is added to the output between ID
+and top level. The parent's ID may be used at mount time via the
+\fIsubvolrootid=\fR option.
+.TP
+
+\fBsubvolume set-default\fR\fI <id> <path>\fR
+Set the subvolume of the filesystem \fI<path>\fR which is mounted as 
+\fIdefault\fR. The subvolume is identified by \fI<id>\fR, which 
+is returned by the \fBsubvolume list\fR command.
+.TP
+
+\fBfilesystem defragment\fP -c[zlib|lzo] [-l \fIlen\fR] [-s \fIstart\fR] [-t \fIsize\fR] -[vf] <\fIfile\fR>|<\fIdir\fR> [<\fIfile\fR>|<\fIdir\fR>...]
+
+Defragment file data and/or directory metadata. To defragment all files in a
+directory you have to specify each one on its own or use your shell wildcards.
+
+The start position and the number of bytes to deframention can be specified by \fIstart\fR and \fIlen\fR. Any extent bigger than \fIthresh\fR will be considered already defragged. Use 0 to take the kernel default, and use 1 to say eveery single extent must be rewritten. You can also turn on compression in defragment operations.
+
+\fB-v\fP be verbose
+
+\fB-c\fP compress file contents while defragmenting
+
+\fB-f\fP flush filesystem after defragmenting
+
+\fB-s start\fP defragment only from byte \fIstart\fR onward
+
+\fB-l len\fP defragment only up to \fIlen\fR bytes
+
+\fB-t size\fP defragment only files at least \fIsize\fR bytes big
+
+NOTE: defragmenting with kernels up to 2.6.37 will unlink COW-ed copies of data, don't 
+use it if you use snapshots, have de-duplicated your data or made copies with 
+\fBcp --reflink\fP.
+\fBsubvolume find-new\fR\fI <subvolume> <last_gen>\fR
+List the recently modified files in a subvolume, after \fI<last_gen>\fR ID.
+.TP
+
+\fBfilesystem sync\fR\fI <path> \fR
+Force a sync for the filesystem identified by \fI<path>\fR.
+.TP
+
+.\"
+.\" Some wording are extracted by the resize2fs man page
+.\"
+
+\fBfilesystem resize\fR\fI [+/\-]<size>[gkm]|max <path>\fR
+Resize a filesystem identified by \fI<path>\fR.
+The \fI<size>\fR parameter specifies the new size of the filesystem.
+If the prefix \fI+\fR or \fI\-\fR is present the size is increased or decreased
+by the quantity \fI<size>\fR.
+If no units are specified, the unit of the \fI<size>\fR parameter defaults to
+bytes. Optionally, the size parameter may be suffixed by one of the following
+the units designators: 'K', 'M', or 'G', kilobytes, megabytes, or gigabytes,
+respectively.
+
+If 'max' is passed, the filesystem will occupy all available space on the
+volume(s).
+
+The \fBresize\fR command \fBdoes not\fR manipulate the size of underlying
+partition.  If you wish to enlarge/reduce a filesystem, you must make sure you
+can expand the partition before enlarging the filesystem and shrink the
+partition after reducing the size of the filesystem.
+.TP
+
+\fBbtrfs\fP \fBfilesystem label\fP\fI <dev> [newlabel]\fP
+Show or update the label of a filesystem. \fI<dev>\fR is used to identify the
+filesystem. 
+If a \fInewlabel\fR optional argument is passed, the label is changed. The
+following costraints exist for a label:
+.IP
+- the maximum allowable lenght shall be less or equal than 256 chars
+.IP
+- the label shall not  contain the '/' or '\\' characters.
+
+NOTE: Currently there are the following limitations:
+.IP
+- the filesystem has to be unmounted
+.IP
+- the filesystem should not have more than one device.
+.TP
+
+\fBfilesystem show\fR [--all-devices|<uuid>|<label>]\fR
+Show the btrfs filesystem with some additional info. If no \fIUUID\fP or 
+\fIlabel\fP is passed, \fBbtrfs\fR show info of all the btrfs filesystem.
+If \fB--all-devices\fP is passed, all the devices under /dev are scanned;
+otherwise the devices list is extracted from the /proc/partitions file.
+.TP
+
+\fBdevice balance\fP [\fB-wcv\fP] [\fB--wait\fP] [\fB--count\fP] [\fB--verbose\fP] [\fB-f\fP|\fBfilter=\fP\fI<filter>\fP] \fI<path>\fP
+.TP
+\fBbalance start\fR [\fB-wcv\fP] [\fB--wait\fP] [\fB--count\fP] [\fB--verbose\fP] [\fB-f\fP|\fBfilter=\fP\fI<filter>\fP] \fI<path>\fP
+
+Balance the chunks of the filesystem identified by \fI<path>\fR across
+the devices. The command returns immediately, and the balance
+operation runs in the background. Use \fB--wait\fP to run
+synchronously instead. Use \fB--count\fP to scan the filesystem and
+report the number of chunks that would be processed. Use
+\fB--verbose\fP in synchronous mode to report the number of chunks
+examined and balanced. See \fBBALANCE FILTERS\fR, below, for details
+of the different filter types and syntax.
+.TP
+
+\fBdevice add\fR\fI <dev> [<dev>..] <path>\fR
+Add device(s) to the filesystem identified by \fI<path>\fR.
+.TP
+
+\fBdevice delete\fR\fI <dev> [<dev>..] <path>\fR
+Remove device(s) from a filesystem identified by \fI<path>\fR.
+.TP
+
+\fBdevice scan\fR \fI[--all-devices|<device> [<device>...]\fR
+If one or more devices are passed, these are scanned for a btrfs filesystem. 
+If no devices are passed, \fBbtrfs\fR scans all the block devices listed
+in the /proc/partitions file.
+Finally, if \fB--all-devices\fP is passed, all the devices under /dev are 
+scanned.
+.TP
+
+\fBscrub start\fP [-Bdqru] {\fI<path>\fP|\fI<device>\fP}
+Start a scrub on all devices of the filesystem identified by \fI<path>\fR or on
+a single \fI<device>\fR. Without options, scrub is started as a background
+process. Progress can be obtained with the \fBscrub status\fR command. Scrubbing
+involves reading all data from all disks and verifying checksums. Errors are
+corrected along the way if possible.
+.RS
+
+\fIOptions\fR
+.IP -B 5
+Do not background and print scrub statistics when finished.
+.IP -d 5
+Print separate statistics for each device of the filesystem (-B only).
+.IP -q 5
+Quiet. Omit error messages and statistics.
+.IP -r 5
+Read only mode. Do not attempt to correct anything.
+.IP -u 5
+Scrub unused space as well. (NOT IMPLEMENTED)
+.RE
+.TP
+
+\fBscrub cancel\fP {\fI<path>\fP|\fI<device>\fP}
+If a scrub is running on the filesystem identified by \fI<path>\fR, cancel it.
+Progress is saved in the scrub progress file and scrubbing can be resumed later
+using the \fBscrub resume\fR command.
+If a \fI<device>\fR is given, the corresponding filesystem is found and
+\fBscrub cancel\fP behaves as if it was called on that filesystem.
+.TP
+
+\fBscrub resume\fP [-Bdqru] {\fI<path>\fP|\fI<device>\fP}
+Resume a canceled or interrupted scrub cycle on the filesystem identified by
+\fI<path>\fR or on a given \fI<device>\fR. Does not start a new scrub if the
+last scrub finished successfully.
+.RS
+
+\fIOptions\fR
+.TP
+see \fBscrub start\fP.
+.RE
+.TP
+
+\fBscrub status\fP [-d] {\fI<path>\fP|\fI<device>\fP}
+Show status of a running scrub for the filesystem identified by \fI<path>\fR or
+for the specified \fI<device>\fR.
+If no scrub is running, show statistics of the last finished or canceled scrub
+for that filesystem or device.
+.RS
+
+\fIOptions\fR
+.IP -d 5
+Print separate statistics for each device of the filesystem.
+.RE
+
+.PP
+
+\fBbalance progress\fP [\fB-m\fP|\fB--monitor\fP] \fI<path>\fP
+Report progress on the currently-running balance operation on the
+filesystem mounted at \fI<path>\fP. Use --monitor to report progress
+continually, including an estimate of completion time.
+
+\fBbalance cancel\fP \fI<path>\fP
+Cancel the balance currently running on the filesystem mounted at
+\fI<path>\fP.
+
+.SH BALANCE FILTERS
+With balance filters, it is possible to perform a balance operation on
+only a subset of the available chunks. Filters are specified with the
+\fB--filter\fR option of \fBbtrfs device balance\fR or \fBbtrfs
+balance start\fR. Multiple filters may be given, either with multiple
+\fB--filter\fR options, or in a colon-separated list. When multiple
+filters are given, only the chunks meeting all of the selection
+critera are balanced. Help on the avaialble filters can be obtained
+with \fB--filter=help\fR.
+
+.TP
+\fBtype\fR=[\fB~\fR]\fI<flagname>\fR[\fB,\fR...]
+
+Select only the chunks with the given type flag(s). Requiring a flag
+to be off can be specified with a \fB~\fR preceding the flag
+name. Flag names are:
+
+\fBmeta\fR, \fBdata\fR, \fBsys\fR for metadata, file data and system
+chunk types.
+
+\fBraid0\fR, \fBraid1\fR, \fBraid10\fR, \fBdup\fR for chunks of the
+given replication levels.
+
+.TP
+\fBdevid\fR=\fI<n>\fR
+
+Select chunks which have data on device ID \fI<n>\fR. This can be
+used, for example, to reduplicate data in a mirrored configuration
+where one drive has been lost due to hardware failure.
+
+.TP
+\fBvrange\fR=\fI<start>\fB,\fI<end>\fR
+
+Select chunks which have btrfs-internal virtual addresses within the
+range \fI<start>\fR (inclusive) to \fI<end>\fR (exclusive). Given the
+address of the last chunk moved, this filter can be used to restart a
+cancelled or interrupted balance operation, by supplying a range of
+\fB0,\fI<chunkaddr+1>\fR.
+
+.TP
+\fBdrange\fR=\fI<start>\fB,\fI<end>\fR
+
+Select chunks which contain data in the address range \fI<start>\fR
+(inclusive) to \fI<end>\fR (exclusive) on \fIany\fR block device in
+the filesystem. Can be mixed with the \fBdevid\fR filter to select
+chunks in a given address range on a specific device.
+
+.SH EXIT STATUS
+\fBbtrfs\fR returns a zero exist status if it succeeds. Non zero is returned in
+case of failure.
+
+.SH AVAILABILITY
+.B 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.
+.SH SEE ALSO
+.BR mkfs.btrfs (8)