blkdiscard: new command

Add to fstrim(8) code to support new discard BLKDISCARD and
BLKSECDISCARD ioctls for block devices.  The new command is only
symlink to fstrim(8) as the both utils share some code and the basic
ideas.

Based on patch from Lukas Czerner <lczerner@redhat.com>.

Signed-off-by: Karel Zak <kzak@redhat.com>

1 files changed, 66 insertions, 0 deletions

diff --git a/sys-utils/blkdiscard.8 b/sys-utils/blkdiscard.8
new file mode 100644
index 000000000..fcc38f6d2
--- /dev/null
+++ b/sys-utils/blkdiscard.8
@@ -0,0 +1,66 @@
+.\" -*- nroff -*-
+.TH BLKDISCARD 8 "September 2012" "util-linux" "System Administration"
+.SH NAME
+blkdiscard \- discard sectors on a device
+.SH SYNOPSIS
+.B blkdiscard
+.RB [ \-o
+.IR offset ]
+.RB [ \-l
+.IR length ]
+.RB [ \-s ]
+.RB [ \-v ]
+.I device
+
+.SH DESCRIPTION
+.B blkdiscard
+is used to discard device sectors. This is useful for solid-state
+drivers (SSDs) and thinly-provisioned storage. Unlike
+.BR fstrim (8)
+this command is used directly on the block device.
+.PP
+By default,
+.B blkdiscard
+will discard all blocks on the device. Options may be used to
+modify this behavior based on range or size, as explained below.
+.PP
+The
+.I device
+argument is the pathname of the block device.
+
+.B WARNING: All data in the discarded region on the device will be lost!
+
+.SH OPTIONS
+The \fIoffset\fR and \fIlength\fR arguments may be
+followed by the multiplicative suffixes KiB=1024, MiB=1024*1024, and so on for
+GiB, TiB, PiB, EiB, ZiB and YiB (the "iB" is optional, e.g. "K" has the same
+meaning as "KiB") or the suffixes KB=1000, MB=1000*1000, and so on for GB, PB,
+EB, ZB and YB.
+.IP "\fB\-h, \-\-help\fP"
+Print help and exit.
+.IP "\fB\-o, \-\-offset\fP \fIoffset\fP"
+Byte offset in the device from which to discard. Provided value will be
+aligned to the device sector size. Default value is zero.
+.IP "\fB\-l, \-\-length\fP \fIlength\fP"
+Number of bytes after starting point to discard. Provided value will be
+aligned to the device sector size. If the specified value extends past the
+end of the device,
+.B blkdiscard
+will stop at the device size boundary. Default value extends to the end
+of the device.
+.IP "\fB\-s, \-\-secure\fP"
+Perform secure discard. Secure discard is the same as regular discard except
+all copies of the discarded blocks possibly created by garbage collection must
+also be erased. It has to be supported by the device.
+.IP "\fB\-v, \-\-verbose\fP"
+Print aligned \fIoffset\fR and \fIlength\fR arguments.
+
+.SH AUTHOR
+.nf
+Lukas Czerner <lczerner@redhat.com>
+.fi
+.SH SEE ALSO
+.BR fstrim (8)
+.SH AVAILABILITY
+The blkdiscard command is part of the util-linux package and is available
+from ftp://ftp.kernel.org/pub/linux/utils/util-linux/.