[PATCH] devfs: be more lax with partition boundaries

[PATCH] devfs: be more lax with partition boundaries

[Uwe Kleine-König]

If a partition starts inside its parent device but is too big such that
it extends over the device boundary, just chop it to the device's end.

This matches the behaviour of Linux.

The motivation for this change is that it makes it possible in some
cases to have the partitioning in a device tree fixed and still allow
different flash sizes.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
---
 fs/devfs-core.c | 14 +++++++++++---
 1 file changed, 11 insertions(+), 3 deletions(-)

diff --git a/fs/devfs-core.c b/fs/devfs-core.c
index f45f8cadf1b0..d456ebccaf06 100644
--- a/fs/devfs-core.c
+++ b/fs/devfs-core.c
@@ -290,12 +290,20 @@ static struct cdev *__devfs_add_partition(struct cdev *cdev,
 
 	*end = offset + size;
 
-	if (offset < 0 || *end > cdev->size) {
-		pr_warn("partition %s not completely inside device %s\n",
-				partinfo->name, cdev->name);
+	if (offset < 0 || offset > cdev->size) {
+		pr_warn("start of partition %s not inside of device %s\n",
+			partinfo->name, cdev->name);
 		return ERR_PTR(-EINVAL);
 	}
 
+	if (*end > cdev->size) {
+		pr_warn("end of partition %s after end of device %s, chopping\n",
+			partinfo->name, cdev->name);
+
+		*end = cdev->size;
+		size = *end - offset;
+	}
+
 	if (IS_ENABLED(CONFIG_MTD) && cdev->mtd) {
 		struct mtd_info *mtd;
 
-- 
2.1.4


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Re: [PATCH] devfs: be more lax with partition boundaries

[Sascha Hauer]

On Thu, May 07, 2015 at 10:45:45AM +0200, Uwe Kleine-König wrote:
> If a partition starts inside its parent device but is too big such that
> it extends over the device boundary, just chop it to the device's end.
> 
> This matches the behaviour of Linux.
> 
> The motivation for this change is that it makes it possible in some
> cases to have the partitioning in a device tree fixed and still allow
> different flash sizes.

When doing it someone is probably annoyed about the warning pretty soon.
I know we just talked whether I would accept this patch, but now I
realized that the correct way to extend the last partition to the end of
the device is to use size 0. This works under barebox and Linux.

Sascha


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Re: [PATCH] devfs: be more lax with partition boundaries

[Uwe Kleine-König]

Hello Sascha,

On Thu, May 07, 2015 at 10:57:02AM +0200, Sascha Hauer wrote:
> On Thu, May 07, 2015 at 10:45:45AM +0200, Uwe Kleine-König wrote:
> > If a partition starts inside its parent device but is too big such that
> > it extends over the device boundary, just chop it to the device's end.
> > 
> > This matches the behaviour of Linux.
> > 
> > The motivation for this change is that it makes it possible in some
> > cases to have the partitioning in a device tree fixed and still allow
> > different flash sizes.
> 
> When doing it someone is probably annoyed about the warning pretty soon.
> I know we just talked whether I would accept this patch, but now I
well, we talked about a change in barebox that makes it match the
behaviour of Linux. So critic to the actual implementation is fine.

> realized that the correct way to extend the last partition to the end of
> the device is to use size 0. This works under barebox and Linux.
Great. Just tested this and it works fine. (I don't know if Linux really
handles this this way, but barebox does and gives the right explicit
size to Linux.)

\o/
Uwe

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Pengutronix e.K.                           | Uwe Kleine-König            |
Industrial Linux Solutions                 | http://www.pengutronix.de/  |

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