linux-kernel - Re: Partition check considered as error is breaking mounting in 2.6.27

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Message-Id: <20080912163416.112152e5.akpm@linux-foundation.org>
Date:	Fri, 12 Sep 2008 16:34:16 -0700
From:	Andrew Morton <akpm@...ux-foundation.org>
To:	Herton Ronaldo Krzesinski <herton@...driva.com.br>
Cc:	linux-kernel@...r.kernel.org, inux-usb@...r.kernel.org,
	bogdano@...driva.com.br, lcapitulino@...driva.com.br
Subject: Re: Partition check considered as error is breaking mounting in
 2.6.27

On Fri, 12 Sep 2008 13:56:49 -0300
Herton Ronaldo Krzesinski <herton@...driva.com.br> wrote:

> Recently I found a problem with a buggy camera that doesn't mount anymore with 
> 2.6.27 (its memory is available via usb-storage), since commit 
> 04ebd4aee52b06a2c38127d9208546e5b96f3a19
> 
> The camera is an Olympus X-840. The original issue comes from the camera 
> itself: its format program creates a partition with an off by one error, 
> while the device reports that its memory has 42079 sectors, the partition 
> table reports also that the only partition on the disk has the size of 42079, 
> but it fails to account for the first sector in the memory that contains the 
> partition table, so in the end the partition exceeds the limit of the device 
> size (42080, first sector plus 42079 from the first partition).
> 
> In previous kernels (2.6.26 and before), I still could mount and access the 
> device (/dev/sdb1), although with the following errors:

Yeah.

Can you test this please?

From: Andrew Morton <akpm@...ux-foundation.org>

Herton Krzesinski reports that the error-checking changes in
04ebd4aee52b06a2c38127d9208546e5b96f3a19 ("block/ioctl.c and
fs/partition/check.c: check value returned by add_partition") cause his
buggy USB camera to no longer mount.  "The camera is an Olympus X-840. 
The original issue comes from the camera itself: its format program
creates a partition with an off by one error".

Buggy devices happen.  It is better for the kernel to warn and to proceed
with the mount.

Reported-by: Herton Ronaldo Krzesinski <herton@...driva.com.br>
Cc: Abdel Benamrouche <draconux@...il.com>
Cc: Jens Axboe <jens.axboe@...cle.com>
Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
---

 fs/partitions/check.c |    1 -
 1 file changed, 1 deletion(-)

diff -puN fs/partitions/check.c~rescan_partitions-make-device-capacity-errors-non-fatal fs/partitions/check.c
--- a/fs/partitions/check.c~rescan_partitions-make-device-capacity-errors-non-fatal
+++ a/fs/partitions/check.c
@@ -540,7 +540,6 @@ int rescan_partitions(struct gendisk *di
 		if (from + size > get_capacity(disk)) {
 			printk(KERN_ERR " %s: p%d exceeds device capacity\n",
 				disk->disk_name, p);
-			continue;
 		}
 		res = add_partition(disk, p, from, size, state->parts[p].flags);
 		if (res) {
_

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