From: Milan Broz <mbroz@redhat.com>
Subject: [RHEL 5.1 PATCH] dm: allow offline devices in table
Date: Thu, 10 May 2007 18:10:56 +0200
Bugzilla: 239655
Message-Id: <46434410.4090300@redhat.com>
Changelog: [md] dm: allow offline devices in table


RHEL5.1 device mapper: allow offline devices in table
Resolves: rhbz#239655
Patch is upstream.

Allow check_device_area to succeed if a device has an i_size of zero. This
addresses an issue seen on DASD devices setting up a multipath table for
paths in online and offline state.

Kernel with fix compiled and tested (also with simple testcase in bugzilla).

---

 drivers/md/dm-table.c |   10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

Index: linux-2.6.18/drivers/md/dm-table.c
===================================================================
--- linux-2.6.18.orig/drivers/md/dm-table.c	2007-05-10 18:07:15.000000000 +0200
+++ linux-2.6.18/drivers/md/dm-table.c	2007-05-10 18:07:19.000000000 +0200
@@ -425,13 +425,15 @@ static void close_dev(struct dm_dev *d, 
 }
 
 /*
- * If possible (ie. blk_size[major] is set), this checks an area
- * of a destination device is valid.
+ * If possible, this checks an area of a destination device is valid.
  */
 static int check_device_area(struct dm_dev *dd, sector_t start, sector_t len)
 {
-	sector_t dev_size;
-	dev_size = dd->bdev->bd_inode->i_size >> SECTOR_SHIFT;
+	sector_t dev_size = dd->bdev->bd_inode->i_size >> SECTOR_SHIFT;
+
+	if (!dev_size)
+		return 1;
+
 	return ((start < dev_size) && (len <= (dev_size - start)));
 }