[PATCH 4/5] fs: devfs: forbid truncation when cdev has no truncate operation

[Sascha Hauer <s.hauer@pengutronix.de>]

When a cdev doesn't have a truncate callback then forbid truncation
and fail with -EPERM.
Before this we had always failed with -ENOSPC in this situation.
We checked for f->fsdev->dev.num_resources being nonzero, but this
check was absolutely meaningless. It goes back to ancient times when
the resources of a device were automatically added to devfs.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
---
 fs/devfs.c | 6 +-----
 1 file changed, 1 insertion(+), 5 deletions(-)

diff --git a/fs/devfs.c b/fs/devfs.c
index aa44e32613..a7400df1c5 100644
--- a/fs/devfs.c
+++ b/fs/devfs.c
@@ -175,11 +175,7 @@ static int devfs_truncate(struct device_d *dev, FILE *f, loff_t size)
 	if (cdev->ops->truncate)
 		return cdev->ops->truncate(cdev, size);
 
-	if (f->fsdev->dev.num_resources < 1)
-		return -ENOSPC;
-	if (size > resource_size(&f->fsdev->dev.resource[0]))
-		return -ENOSPC;
-	return 0;
+	return -EPERM;
 }
 
 static struct inode *devfs_alloc_inode(struct super_block *sb)
-- 
2.20.1


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