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Re: [dm-devel] [PATCH] dm.c

On Fri May 5 2006 2:35 am, m9230 wrote:
> I am sorry that I did not list the original source.
> Thanks to Eric, this is the original source:
> http://oss.sgi.com/bugzilla/show_bug.cgi?id=646
> > Hello, I found a problem in dm_blk_ioctl() in dm.c:
> >
> > In dm.c, dm_blk_ioctl() is assigning a full unsigned 32 bits of
> > device size to a signed 32 bit size. This may cause BLKGETSIZE64
> > ioctl and BLKGETSIZE ioctl failed to get the device size when device
> > size is larger than 1TB.
> >
> > I am using device-mapper.1.01.05.
> >
> > Changing "long size;" to "sector_t size;" might fix this up, it
> > works for me. For example: error = ioctl(fd, BLKGETSIZE64, &size);
> > returns "size" in bytes.

I haven't seen an actual patch yet for this bug, so here's one with the 
suggested fix (against 2.4.31 + device-mapper-1.02.05).

Kevin Corry
kevcorry us ibm com

In dm_blk_ioctl(), change 'size' to a sector_t so we can correctly return
the size of devices between 1 and 2 TB.

Fix suggested by Eric Sandeen <sandeen sgi com>

Signed-Off-By: Kevin Corry <kevcorry us ibm com>

Index: 2.4.31/drivers/md/dm.c
--- 2.4.31.orig/drivers/md/dm.c
+++ 2.4.31/drivers/md/dm.c
@@ -456,7 +456,7 @@ static int dm_blk_ioctl(struct inode *in
 			unsigned int command, unsigned long a)
 	kdev_t dev = inode->i_rdev;
-	long size;
+	sector_t size;
 	switch (command) {
 	case BLKROSET:
@@ -476,7 +476,7 @@ static int dm_blk_ioctl(struct inode *in
 		size = volume_size(dev);
-		if (copy_to_user((void *) a, &size, sizeof(long)))
+		if (put_user((unsigned long) size, (unsigned long *) a))
 			return -EFAULT;

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