From: Eric Sandeen <sandeen@redhat.com>
Date: Tue, 8 Jul 2008 15:19:52 -0500
Subject: [fs] add an ERR_CAST function
Message-id: 4873CBE8.5020108@redhat.com
O-Subject: [PATCH RHEL5 5/9] ERR_CAST
Bugzilla: 443896
RH-Acked-by: Jeff Moyer <jmoyer@redhat.com>
RH-Acked-by: Jeff Layton <jlayton@redhat.com>
RH-Acked-by: Alexander Viro <aviro@redhat.com>

This is for:

Bugzilla Bug 443896: RFE: [Ext4 enabler] backport vfs
helpers to facilitate ext4 backport and testing

From: David Howells <dhowells@redhat.com>
Date: Thu, 7 Feb 2008 08:15:26 +0000 (-0800)
Subject: Add an ERR_CAST() function to complement ERR_PTR and co.
X-Git-Tag: v2.6.25-rc1~388
X-Git-Url: http://git.engineering.redhat.com/?p=linux-2.6.git;a=commitdiff_plain;h=d1bc8e95445224276d7896b8b08cbb0b28a0ca80

Add an ERR_CAST() function to complement ERR_PTR and co.

Add an ERR_CAST() function to complement ERR_PTR and co.  for the purposes
of casting an error entyped as one pointer type to an error of another
pointer type whilst making it explicit as to what is going on.

This provides a replacement for the ERR_PTR(PTR_ERR(p)) construct.

Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/include/linux/err.h b/include/linux/err.h
index cd3b367..03639cb 100644
--- a/include/linux/err.h
+++ b/include/linux/err.h
@@ -32,4 +32,17 @@ static inline long IS_ERR(const void *ptr)
 	return IS_ERR_VALUE((unsigned long)ptr);
 }
 
+/**
+ * ERR_CAST - Explicitly cast an error-valued pointer to another pointer type
+ * @ptr: The pointer to cast.
+ *
+ * Explicitly cast an error-valued pointer to another pointer type in such a
+ * way as to make it clear that's what's going on.
+ */
+static inline void *ERR_CAST(const void *ptr)
+{
+	/* cast away the const */
+	return (void *) ptr;
+}
+
 #endif /* _LINUX_ERR_H */