[PATCH] (quickfix) allow md devices to be used in 2.5.43

[PATCH] (quickfix) allow md devices to be used in 2.5.43

[David Mansfield]

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Al, list,

In order to accessing my md devices in 2.5.43, i needed the attached
patch to fs/block_dev.c.  WARNING: it's probably very broken, because I
don't know what I'm doing.  I essentially reverted most of the changes to
the do_open function, allowing the open() method of a device without an
attached gendisk to be called.

In the md scheme of things, the gendisk is created in the md_run stage, 
which is only possible via ioctl after a successful open of the block 
device.

However, something else is broken with the change to md.c, which detects
whether the disk is idle by checking the number of sectors read/written to
the disk.

I'm going to take a look at that now.

David

-- 
/==============================\
| David Mansfield              |
| david@cobite.com             |
\==============================/

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--- linux-2.5.43/fs/block_dev.c	Mon Sep 16 07:25:59 2002
+++ linux-currentish-vanilla/fs/block_dev.c	Mon Sep 16 10:54:59 2002
@@ -612,12 +612,12 @@
 		if (owner)
 			__MOD_DEC_USE_COUNT(owner);
 	}
+
 	disk = get_gendisk(bdev->bd_dev, &part);
-	if (!disk)
-		goto out1;
+
 	if (!bdev->bd_contains) {
 		bdev->bd_contains = bdev;
-		if (part) {
+		if (disk && part) {
 			struct block_device *whole;
 			whole = bdget(MKDEV(disk->major, disk->first_minor));
 			ret = -ENOMEM;
@@ -630,8 +630,6 @@
 		}
 	}
 	if (bdev->bd_contains == bdev) {
-		if (!bdev->bd_openers)
-			bdev->bd_disk = disk;
 		if (!bdev->bd_queue) {
 			struct blk_dev_struct *p = blk_dev + major(dev);
 			bdev->bd_queue = &p->request_queue;
@@ -645,8 +643,12 @@
 		}
 		if (!bdev->bd_openers) {
 			struct backing_dev_info *bdi;
+			sector_t sect = 0;
+
 			bdev->bd_offset = 0;
-			bd_set_size(bdev, (loff_t)get_capacity(disk) << 9);
+			if (disk)
+				sect = get_capacity(disk);
+			bd_set_size(bdev, (loff_t)sect << 9);
 			bdi = blk_get_backing_dev_info(bdev);
 			if (bdi == NULL)
 				bdi = &default_backing_dev_info;