Separate out md superblock detection code.

WHATS_NEW

@@ -1,5 +1,6 @@
 Version 2.00.26 - 
 =====================================
+  Separate out md superblock detection code.
   Prevent snapshot origin resizing.
   Improve a vgremove error message.
   Update some man pages.

lib/Makefile.in

@@ -43,6 +43,7 @@ SOURCES =\
 	datastruct/str_list.c \
 	device/dev-cache.c \
 	device/dev-io.c \
+	device/dev-md.c \
 	device/device.c \
 	display/display.c \
 	error/errseg.c \

lib/device/dev-md.c

@@ -0,0 +1,68 @@
+/*
+ * Copyright (C) 2004 Luca Berra
+ * Copyright (C) 2004 Red Hat, Inc. All rights reserved.
+ *
+ * This file is part of LVM2.
+ *
+ * This copyrighted material is made available to anyone wishing to use,
+ * modify, copy, or redistribute it subject to the terms and conditions
+ * of the GNU Lesser General Public License v.2.1.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ */
+
+#include "lib.h"
+#include "metadata.h"
+
+/* Lifted from <linux/raid/md_p.h> because of difficulty including it */
+
+#define MD_SB_MAGIC 0xa92b4efc
+#define MD_RESERVED_BYTES (64 * 1024)
+#define MD_RESERVED_SECTORS (MD_RESERVED_BYTES / 512)
+#define MD_NEW_SIZE_SECTORS(x) ((x & ~(MD_RESERVED_SECTORS - 1)) \
+				- MD_RESERVED_SECTORS)
+
+/*
+ * Returns -1 on error
+ */
+int dev_is_md(struct device *dev, uint64_t *sb)
+{
+	int ret = 0;
+
+#ifdef linux
+
+	uint64_t size, sb_offset;
+	uint32_t md_magic;
+
+	if (!dev_get_size(dev, &size)) {
+		stack;
+		return -1;
+	}
+
+	if (size < MD_RESERVED_SECTORS * 2)
+		return 0;
+
+	if (!dev_open(dev)) {
+		stack;
+		return -1;
+	}
+
+	sb_offset = MD_NEW_SIZE_SECTORS(size) << SECTOR_SHIFT;
+
+	/* Check if it is an md component device. */
+	if (dev_read(dev, sb_offset, sizeof(uint32_t), &md_magic) &&
+	    (md_magic == MD_SB_MAGIC)) {
+		if (sb)
+			*sb = sb_offset;
+		ret = 1;
+	}
+
+	if (!dev_close(dev))
+		stack;
+
+#endif
+	return ret;
+}
+

lib/device/device.h

@@ -89,6 +89,9 @@ static inline const char *dev_name(const struct device *dev)
 /* Return a valid device name from the alias list; NULL otherwise */
 const char *dev_name_confirmed(struct device *dev, int quiet);
 
+/* Does device contain md superblock?  If so, where? */
+int dev_is_md(struct device *dev, uint64_t *sb);
+
 /* FIXME Check partition type if appropriate */
 
 #define is_lvm_partition(a) 1

lib/filters/filter-md.c

@@ -28,42 +28,18 @@
 
 static int _ignore_md(struct dev_filter *f, struct device *dev)
 {
-	uint64_t size, sector;
-	uint32_t md_magic;
+	int ret = dev_is_md(dev, NULL);
 
-	if (!dev_get_size(dev, &size)) {
-		stack;
+	if (ret == 1) {
+		log_debug("%s: Skipping md component device", dev_name(dev));
 		return 0;
 	}
 
-	if (size < MD_RESERVED_SECTORS * 2)
-		/*
-		 * We could ignore it since it is obviously too
-		 * small, but that's not our job.
-		 */
-		return 1;
-
-	if (!dev_open(dev)) {
-		stack;
+	if (ret < 0) {
+		log_debug("%s: Skipping: error in md component detection");
 		return 0;
 	}
 
-	sector = MD_NEW_SIZE_SECTORS(size);
-
-	/* Check if it is an md component device. */
-	if (dev_read(dev, sector << SECTOR_SHIFT, sizeof(uint32_t), &md_magic)) {
-		if (md_magic == MD_SB_MAGIC) {
-			log_debug("%s: Skipping md component device",
-				  dev_name(dev));
-			if (!dev_close(dev))
-				stack;
-			return 0;
-		}
-	}
-
-	if (!dev_close(dev))
-		stack;
-
 	return 1;
 }