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

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

[Fabian Frederick]

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

Signed-off-by: Fabian Frederick <fabf@skynet.be>
---
 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

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

[Ezequiel Garcia]

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

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

[Fabian Frederick]

On Wed, 29 Jan 2014 07:04:25 -0300
Ezequiel Garcia <ezequiel.garcia@free-electrons.com> 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 García, Free Electrons
> Embedded Linux, Kernel and Android Engineering
> http://free-electrons.com

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

[Brian Norris]

Hi,

On Wed, Jan 29, 2014 at 08:51:05PM +0800, Fabian Frederick wrote:
> On Wed, 29 Jan 2014 07:04:25 -0300 Ezequiel Garcia <ezequiel.garcia@free-electrons.com> wrote:
> > 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

I'm not sure block2mtd would have many users, but the hunk above looks
reasonable. Feel free to send a patch.

>    AFAICS, current behavior let any value work...

I bet this doesn't work out too well in the end. Maybe I'll give this a
whirl just to see.

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

Brian

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

[Fabian Frederick]

On Thu, 6 Mar 2014 00:54:22 -0800
Brian Norris <computersforpeace@gmail.com> wrote:

> Hi,
> 
> On Wed, Jan 29, 2014 at 08:51:05PM +0800, Fabian Frederick wrote:
> > On Wed, 29 Jan 2014 07:04:25 -0300 Ezequiel Garcia <ezequiel.garcia@free-electrons.com> wrote:
> > > 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
> 
> I'm not sure block2mtd would have many users, but the hunk above looks
> reasonable. Feel free to send a patch.

Hi Brian,

   I just send a patch v2 based on linux-next to avoid conflicts with my previous commit about
 mutex management in the same function and still staging there.

Fabian

> 
> >    AFAICS, current behavior let any value work...
> 
> I bet this doesn't work out too well in the end. Maybe I'll give this a
> whirl just to see.
> 
> >  PS : This would need further testing (eg boot command).
> 
> Brian

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

[Ezequiel Garcia]

On Mar 06, Brian Norris wrote:
[..]
> 
> I'm not sure block2mtd would have many users, but the hunk above looks
> reasonable. Feel free to send a patch.
> 

I've bounced you the original patch from Fabian.
-- 
Ezequiel García, Free Electrons
Embedded Linux, Kernel and Android Engineering
http://free-electrons.com