2014-01-23 19:53:34

by Fabian Frédérick

[permalink] [raw]
Subject: [PATCH 3/4] mtd: block2mtd: check device size

fixme applied : check device size is a multiple of erasesize.

Signed-off-by: Fabian Frederick <[email protected]>
---
drivers/mtd/devices/block2mtd.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/mtd/devices/block2mtd.c b/drivers/mtd/devices/block2mtd.c
index 8071596..f0fd4fc 100644
--- a/drivers/mtd/devices/block2mtd.c
+++ b/drivers/mtd/devices/block2mtd.c
@@ -209,7 +209,6 @@ static void block2mtd_free_device(struct block2mtd_dev *dev)
}


-/* FIXME: ensure that mtd->size % erase_size == 0 */
static struct block2mtd_dev *add_device(char *devname, int erase_size)
{
const fmode_t mode = FMODE_READ | FMODE_WRITE | FMODE_EXCL;
@@ -250,6 +249,11 @@ static struct block2mtd_dev *add_device(char *devname, int erase_size)
goto devinit_err1;
}

+ if ((long)dev->blkdev->bd_inode->i_size % erase_size) {
+ pr_err("erasesize muse be a divisor of device size\n");
+ goto devinit_err1;
+ }
+
mutex_init(&dev->write_mutex);

/* Setup the MTD structure */
--
1.8.1.4


2014-01-29 10:04:17

by Ezequiel Garcia

[permalink] [raw]
Subject: Re: [PATCH 3/4] mtd: block2mtd: check device size

Hi Fabian,

I saw you sent a v2 for one of the patches on this series,
but maybe this is worth considering too.

On Thu, Jan 23, 2014 at 08:53:31PM +0100, Fabian Frederick wrote:
[..]
> -/* FIXME: ensure that mtd->size % erase_size == 0 */
> static struct block2mtd_dev *add_device(char *devname, int erase_size)
> {
> const fmode_t mode = FMODE_READ | FMODE_WRITE | FMODE_EXCL;
> @@ -250,6 +249,11 @@ static struct block2mtd_dev *add_device(char *devname, int erase_size)
> goto devinit_err1;
> }
>
> + if ((long)dev->blkdev->bd_inode->i_size % erase_size) {
> + pr_err("erasesize muse be a divisor of device size\n");
> + goto devinit_err1;
> + }
> +

Brian: What do you think?

Fabian: Have you tested this patch? Can you elaborate a bit more about
the effect it would have, compared to the current behavior?
--
Ezequiel García, Free Electrons
Embedded Linux, Kernel and Android Engineering
http://free-electrons.com

2014-01-29 20:49:55

by Fabian Frédérick

[permalink] [raw]
Subject: Re: [PATCH 3/4] mtd: block2mtd: check device size

On Wed, 29 Jan 2014 07:04:25 -0300
Ezequiel Garcia <[email protected]> wrote:

> Hi Fabian,
>
> I saw you sent a v2 for one of the patches on this series,
> but maybe this is worth considering too.
>
> On Thu, Jan 23, 2014 at 08:53:31PM +0100, Fabian Frederick wrote:
> [..]
> > -/* FIXME: ensure that mtd->size % erase_size == 0 */
> > static struct block2mtd_dev *add_device(char *devname, int erase_size)
> > {
> > const fmode_t mode = FMODE_READ | FMODE_WRITE | FMODE_EXCL;
> > @@ -250,6 +249,11 @@ static struct block2mtd_dev *add_device(char *devname, int erase_size)
> > goto devinit_err1;
> > }
> >
> > + if ((long)dev->blkdev->bd_inode->i_size % erase_size) {
> > + pr_err("erasesize muse be a divisor of device size\n");
> > + goto devinit_err1;
> > + }
> > +
>
> Brian: What do you think?
>
> Fabian: Have you tested this patch? Can you elaborate a bit more about
> the effect it would have, compared to the current behavior?

Hi Ezequiel,

This patch was tested with the following commands :

rmmod block2mtd;modprobe block2mtd block2mtd=/dev/loop0,<erasesize>;dmesg

with both correct and incorrect values.It tries to address the fixme
comment above the function.
(/* FIXME: ensure that mtd->size % erase_size == 0 */)

From what I understand, global size must be a multiple of
erase_size when it comes to any MTD I/O operations. If Brian finds this one
interesting I can repost it with current error names against l2-mtd.git/next

AFAICS, current behavior let any value work...

PS : This would need further testing (eg boot command).

Regards,
Fabian


> --
> Ezequiel Garc?a, Free Electrons
> Embedded Linux, Kernel and Android Engineering
> http://free-electrons.com