[PATCH 02/10] xfs_io: support using XFS_IOC_MAP_FREESP to map free space

["Darrick J. Wong" <djwong@kernel.org>]

From: Darrick J. Wong <djwong@kernel.org>

Add a command to call XFS_IOC_MAP_FREESP.  This is experimental code to
see if we can build a free space defragmenter out of this.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
---
 io/prealloc.c     |   35 +++++++++++++++++++++++++++++++++++
 man/man8/xfs_io.8 |    8 +++++++-
 2 files changed, 42 insertions(+), 1 deletion(-)


diff --git a/io/prealloc.c b/io/prealloc.c
index 5805897a4a0..0de3e142de1 100644
--- a/io/prealloc.c
+++ b/io/prealloc.c
@@ -45,6 +45,7 @@ static cmdinfo_t finsert_cmd;
 static cmdinfo_t fzero_cmd;
 static cmdinfo_t funshare_cmd;
 #endif
+static cmdinfo_t fmapfree_cmd;
 
 static int
 offset_length(
@@ -383,6 +384,30 @@ funshare_f(
 }
 #endif	/* HAVE_FALLOCATE */
 
+static int
+fmapfree_f(
+	int			argc,
+	char			**argv)
+{
+	struct xfs_flock64	segment;
+	struct xfs_map_freesp	args = { };
+
+	if (!offset_length(argv[1], argv[2], &segment)) {
+		exitcode = 1;
+		return 0;
+	}
+
+	args.offset = segment.l_start;
+	args.len = segment.l_len;
+
+	if (ioctl(file->fd, XFS_IOC_MAP_FREESP, &args)) {
+		perror("XFS_IOC_MAP_FREESP");
+		exitcode = 1;
+		return 0;
+	}
+	return 0;
+}
+
 void
 prealloc_init(void)
 {
@@ -497,4 +522,14 @@ prealloc_init(void)
 	_("unshares shared blocks within the range");
 	add_command(&funshare_cmd);
 #endif	/* HAVE_FALLOCATE */
+
+	fmapfree_cmd.name = "fmapfree";
+	fmapfree_cmd.cfunc = fmapfree_f;
+	fmapfree_cmd.argmin = 2;
+	fmapfree_cmd.argmax = 2;
+	fmapfree_cmd.flags = CMD_NOMAP_OK | CMD_FOREIGN_OK;
+	fmapfree_cmd.args = _("off len");
+	fmapfree_cmd.oneline =
+	_("maps free space into a file");
+	add_command(&fmapfree_cmd);
 }
diff --git a/man/man8/xfs_io.8 b/man/man8/xfs_io.8
index 411144151a1..e360d22dc38 100644
--- a/man/man8/xfs_io.8
+++ b/man/man8/xfs_io.8
@@ -513,8 +513,14 @@ Call fallocate with FALLOC_FL_INSERT_RANGE flag as described in the
 .BR fallocate (2)
 manual page to create the hole by shifting data blocks.
 .TP
+.BI fmapfree " offset length"
+Maps free physical space into the file by calling XFS_IOC_MAP_FREESP as
+described in the
+.BR XFS_IOC_MAP_FREESP (2)
+manual page.
+.TP
 .BI fpunch " offset length"
-Punches (de-allocates) blocks in the file by calling fallocate with 
+Punches (de-allocates) blocks in the file by calling fallocate with
 the FALLOC_FL_PUNCH_HOLE flag as described in the
 .BR fallocate (2)
 manual page.