On Fri, 27 Jul 2012 13:09:53 +0200, Stefan Behrens wrote:

On Fri, 27 Jul 2012 16:04:14 +0530, Nageswara R Sastry wrote:

quoted

Check for the return value of 'open_ctree()' before dereferencing it.

Signed-off-by: Nageswara R Sastry <redacted>
---
 btrfs-image.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/btrfs-image.c b/btrfs-image.c
index f2bbcc8..2a33a55 100644
--- a/btrfs-image.c
+++ b/btrfs-image.c

@@ -491,6 +491,7 @@ static int create_metadump(const char *input, FILE *out, int num_threads,
 	int ret;
 
 	root = open_ctree(input, 0, 0);
+	BUG_ON(!root);
 	BUG_ON(root->nodesize != root->leafsize);
 
 	ret = metadump_init(&metadump, root, out, num_threads,

In general, explicit BUG_ON() checks for a NULL pointer are not added to
the Linux kernel if the pointer is dereferenced afterwards. When the
NULL area is accessed, you get a general protection fault including the
call trace and a dump of all registers. Adding explicit BUG_ON(ptr !=
NULL) adds overhead without bringing any additional information.

Please ignore and excuse my noise from before. Your patch is for
btrfs-progs, not for the kernel.