[PATCH] btrfs-progs: check: Fix false alert about uninitialized

[PATCH] btrfs-progs: check: Fix false alert about uninitialized

[Qu Wenruo]

GCC 8.2.1 will report the following error:

  check/main.c: In function 'try_repair_inode':
  check/main.c:2606:5: warning: 'ret' may be used uninitialized in this function [-Wmaybe-uninitialized]
    if (!ret) {
       ^
  check/main.c:2584:6: note: 'ret' was declared here
    int ret;
        ^~~

The offending code is in repair_mismatch_dir_hash():

	int ret;

	printf(
	"Deleting bad dir items with invalid hash for root %llu ino %llu\n",
		root->root_key.objectid, rec->ino);
	while (!list_empty(&rec->mismatch_dir_hash)) {
		/* do some repair */
	}
	if (!ret) { <<< Here
		/* do some fix */
	}

The truth is, to enter try_repair_inode(), we must have
I_ERR_MISMATCH_DIR_HASH bit set for rec->errors.

And just after we set I_ERR_MISMATCH_DIR_HASH, we call
add_mismatch_dir_hash() and handled its error correctly.

So it's impossible to to skip the while loop.

Fix it by initializing @ret to -EUCLEAN, so even we hit some impossible
case, repair_mismatch_dir_hash() won't falsely consider the mismatch
hash fixed.

Signed-off-by: Qu Wenruo <wqu@suse.com>
---
 check/main.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/check/main.c b/check/main.c
index 951a23b1e26a..ea078e023d24 100644
--- a/check/main.c
+++ b/check/main.c
@@ -2581,7 +2581,7 @@ static int repair_mismatch_dir_hash(struct btrfs_trans_handle *trans,
 				    struct inode_record *rec)
 {
 	struct mismatch_dir_hash_record *hash;
-	int ret;
+	int ret = -EUCLEAN;
 
 	printf(
 	"Deleting bad dir items with invalid hash for root %llu ino %llu\n",
-- 
2.21.0

Re: [PATCH] btrfs-progs: check: Fix false alert about uninitialized

[David Sterba]

On Wed, Feb 27, 2019 at 01:49:52PM +0800, Qu Wenruo wrote:
> GCC 8.2.1 will report the following error:
> 
>   check/main.c: In function 'try_repair_inode':
>   check/main.c:2606:5: warning: 'ret' may be used uninitialized in this function [-Wmaybe-uninitialized]
>     if (!ret) {
>        ^
>   check/main.c:2584:6: note: 'ret' was declared here
>     int ret;
>         ^~~
> 
> The offending code is in repair_mismatch_dir_hash():
> 
> 	int ret;
> 
> 	printf(
> 	"Deleting bad dir items with invalid hash for root %llu ino %llu\n",
> 		root->root_key.objectid, rec->ino);
> 	while (!list_empty(&rec->mismatch_dir_hash)) {
> 		/* do some repair */
> 	}
> 	if (!ret) { <<< Here
> 		/* do some fix */
> 	}
> 
> The truth is, to enter try_repair_inode(), we must have
> I_ERR_MISMATCH_DIR_HASH bit set for rec->errors.
> 
> And just after we set I_ERR_MISMATCH_DIR_HASH, we call
> add_mismatch_dir_hash() and handled its error correctly.
> 
> So it's impossible to to skip the while loop.
> 
> Fix it by initializing @ret to -EUCLEAN, so even we hit some impossible
> case, repair_mismatch_dir_hash() won't falsely consider the mismatch
> hash fixed.
> 
> Signed-off-by: Qu Wenruo <wqu@suse.com>

Applied, thanks.