xfs_io: add a new 'log_writes' command

Add a new 'log_writes' command to xfs_io so that we can add dm-log-writes
log marks.  It's helpful to allow users of xfs_io to adds these marks from
within xfs_io instead of waiting until after xfs_io exits because then they
are able to replay the dm-log-writes log up to immediately after another
xfs_io operation such as mwrite.  This isolates the log replay from other
operations that happen as part of xfs_io exiting (file handles being
closed, mmaps being torn down, etc.).  This also allows users to insert
multiple marks between different xfs_io commands.

Signed-off-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Suggested-by: Dave Chinner <david@fromorbit.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Eric Sandeen <sandeen@sandeen.net>

10 files changed, 157 insertions, 2 deletions

diff --git a/configure.ac b/configure.ac
index f3325aa044..f83d5817b8 100644
--- a/configure.ac
+++ b/configure.ac
@@ -164,6 +164,7 @@ AC_NEED_INTERNAL_FSXATTR
 AC_HAVE_GETFSMAP
 AC_HAVE_STATFS_FLAGS
 AC_HAVE_MAP_SYNC
+AC_HAVE_DEVMAPPER
 
 if test "$enable_blkid" = yes; then
 AC_HAVE_BLKID_TOPO
diff --git a/debian/control b/debian/control
index ad81662262..5c26e3d7e1 100644
--- a/debian/control
+++ b/debian/control
@@ -3,7 +3,7 @@ Section: admin
 Priority: optional
 Maintainer: XFS Development Team <linux-xfs@vger.kernel.org>
 Uploaders: Nathan Scott <nathans@debian.org>, Anibal Monsalve Salazar <anibal@debian.org>
-Build-Depends: uuid-dev, dh-autoreconf, debhelper (>= 5), gettext, libtool, libreadline-gplv2-dev | libreadline5-dev, libblkid-dev (>= 2.17), linux-libc-dev
+Build-Depends: uuid-dev, dh-autoreconf, debhelper (>= 5), gettext, libtool, libreadline-gplv2-dev | libreadline5-dev, libblkid-dev (>= 2.17), linux-libc-dev, libdevmapper-dev
 Standards-Version: 3.9.1
 Homepage: http://xfs.org/
 
diff --git a/include/builddefs.in b/include/builddefs.in
index 1f33022321..94707038ce 100644
--- a/include/builddefs.in
+++ b/include/builddefs.in
@@ -35,6 +35,7 @@ LIBTERMCAP = @libtermcap@
 LIBEDITLINE = @libeditline@
 LIBREADLINE = @libreadline@
 LIBBLKID = @libblkid@
+LIBDEVMAPPER = @libdevmapper@
 LIBXFS = $(TOPDIR)/libxfs/libxfs.la
 LIBFROG = $(TOPDIR)/libfrog/libfrog.la
 LIBXCMD = $(TOPDIR)/libxcmd/libxcmd.la
@@ -117,6 +118,7 @@ NEED_INTERNAL_FSXATTR = @need_internal_fsxattr@
 HAVE_GETFSMAP = @have_getfsmap@
 HAVE_STATFS_FLAGS = @have_statfs_flags@
 HAVE_MAP_SYNC = @have_map_sync@
+HAVE_DEVMAPPER = @have_devmapper@
 
 GCCFLAGS = -funsigned-char -fno-strict-aliasing -Wall
 #	   -Wbitwise -Wno-transparent-union -Wno-old-initializer -Wno-decl
diff --git a/io/Makefile b/io/Makefile
index 979434a2a1..8055d4bd31 100644
--- a/io/Makefile
+++ b/io/Makefile
@@ -108,6 +108,12 @@ ifeq ($(HAVE_MAP_SYNC),yes)
 LCFLAGS += -DHAVE_MAP_SYNC
 endif
 
+ifeq ($(HAVE_DEVMAPPER),yes)
+CFILES += log_writes.c
+LLDLIBS += $(LIBDEVMAPPER)
+LCFLAGS += -DHAVE_DEVMAPPER
+endif
+
 # On linux we get fsmap from the system or define it ourselves
 # so include this based on platform type.  If this reverts to only
 # the autoconf check w/o local definition, change to testing HAVE_GETFSMAP
diff --git a/io/init.c b/io/init.c
index 9e576fe203..6f47ed2505 100644
--- a/io/init.c
+++ b/io/init.c
@@ -72,6 +72,7 @@ init_commands(void)
 	help_init();
 	imap_init();
 	inject_init();
+	log_writes_init();
 	madvise_init();
 	mincore_init();
 	mmap_init();
diff --git a/io/io.h b/io/io.h
index 5255c08705..5cf7c3084b 100644
--- a/io/io.h
+++ b/io/io.h
@@ -187,4 +187,10 @@ extern void		fsmap_init(void);
 # define fsmap_init()	do { } while (0)
 #endif
 
+#ifdef HAVE_DEVMAPPER
+extern void		log_writes_init(void);
+#else
+#define log_writes_init()      do { } while (0)
+#endif
+
 extern void		scrub_init(void);
diff --git a/io/log_writes.c b/io/log_writes.c
new file mode 100644
index 0000000000..46ea1c2621
--- /dev/null
+++ b/io/log_writes.c
@@ -0,0 +1,106 @@
+/*
+ * Copyright (c) 2017 Intel Corporation.
+ * All Rights Reserved.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it would be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write the Free Software Foundation,
+ * Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+ */
+
+#include "platform_defs.h"
+#include <libdevmapper.h>
+#include "command.h"
+#include "init.h"
+
+static cmdinfo_t log_writes_cmd;
+
+static int
+mark_log(const char *device, const char *mark)
+{
+	struct dm_task 	*dmt;
+	const int 	size = 80;
+	char 		message[size];
+	int 		len, ret = 0;
+
+	len = snprintf(message, size, "mark %s", mark);
+	if (len >= size) {
+		printf("mark '%s' is too long\n", mark);
+		return ret;
+	}
+
+	if (!(dmt = dm_task_create(DM_DEVICE_TARGET_MSG)))
+		return ret;
+
+	if (!dm_task_set_name(dmt, device))
+		goto out;
+
+	if (!dm_task_set_sector(dmt, 0))
+		goto out;
+
+	if (!dm_task_set_message(dmt, message))
+		goto out;
+
+	if (dm_task_run(dmt))
+		ret = 1;
+out:
+	dm_task_destroy(dmt);
+	return ret;
+}
+
+static int
+log_writes_f(
+	int			argc,
+	char			**argv)
+{
+	const char 	*device = NULL;
+	const char 	*mark = NULL;
+	int 		c;
+
+	exitcode = 1;
+	while ((c = getopt(argc, argv, "d:m:")) != EOF) {
+		switch (c) {
+		case 'd':
+			device = optarg;
+			break;
+		case 'm':
+			mark = optarg;
+			break;
+		default:
+			return command_usage(&log_writes_cmd);
+		}
+	}
+
+	if (device == NULL || mark == NULL)
+		return command_usage(&log_writes_cmd);
+
+	if (mark_log(device, mark))
+		exitcode = 0;
+
+	return 0;
+}
+
+void
+log_writes_init(void)
+{
+	log_writes_cmd.name = "log_writes";
+	log_writes_cmd.altname = "lw";
+	log_writes_cmd.cfunc = log_writes_f;
+	log_writes_cmd.flags = CMD_NOMAP_OK | CMD_NOFILE_OK | CMD_FOREIGN_OK
+				| CMD_FLAG_ONESHOT;
+	log_writes_cmd.argmin = 0;
+	log_writes_cmd.argmax = -1;
+	log_writes_cmd.args = _("-d device -m mark");
+	log_writes_cmd.oneline =
+		_("create mark <mark> in the dm-log-writes log specified by <device>");
+
+	add_command(&log_writes_cmd);
+}
diff --git a/m4/Makefile b/m4/Makefile
index 4706121b4b..77f2edda9d 100644
--- a/m4/Makefile
+++ b/m4/Makefile
@@ -15,6 +15,7 @@ CONFIGURE = \
 LSRCFILES = \
 	manual_format.m4 \
 	package_blkid.m4 \
+	package_devmapper.m4 \
 	package_globals.m4 \
 	package_libcdev.m4 \
 	package_pthread.m4 \
diff --git a/m4/package_devmapper.m4 b/m4/package_devmapper.m4
new file mode 100644
index 0000000000..821f283cc0
--- /dev/null
+++ b/m4/package_devmapper.m4
@@ -0,0 +1,11 @@
+#
+# See if libdevmapper is available on the system.
+#
+AC_DEFUN([AC_HAVE_DEVMAPPER],
+[ AC_SEARCH_LIBS([dm_task_create], [devmapper],
+        libdevmapper="-ldevmapper"
+        have_devmapper=yes,
+        have_devmapper=no,)
+    AC_SUBST(have_devmapper)
+    AC_SUBST(libdevmapper)
+])
diff --git a/man/man8/xfs_io.8 b/man/man8/xfs_io.8
index 3f77781f33..b47076082a 100644
--- a/man/man8/xfs_io.8
+++ b/man/man8/xfs_io.8
@@ -1143,7 +1143,27 @@ parameter specifies which type of metadata to scrub.
 For AG metadata, one AG number must be specified.
 For file metadata, the scrub is applied to the open file unless the
 inode number and generation number are specified.
+.RE
+.PD
+.TP
+.BI "log_writes \-d " device " \-m "  mark
+Create a mark named
+.I mark
+in the dm-log-writes log specified by
+.I device.
+This is intended to be equivalent to the shell command:
 
+.B dmsetup message
+.I device
+.B 0 mark
+.I mark
+.PD
+.RE
+.TP
+.B lw
+See the
+.B log_writes
+command.
 .SH SEE ALSO
 .BR mkfs.xfs (8),
 .BR xfsctl (3),
@@ -1161,4 +1181,5 @@ inode number and generation number are specified.
 .BR open (2),
 .BR pread (2),
 .BR pwrite (2),
-.BR readdir (3).
+.BR readdir (3),
+.BR dmsetup (8).