linux-kernel - [PATCH] btrfs: shut up bogus -Wmaybe-uninitialized warning

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Date:   Mon, 17 Jun 2019 13:07:28 +0200
From:   Arnd Bergmann <arnd@...db.de>
To:     Chris Mason <clm@...com>, Josef Bacik <josef@...icpanda.com>,
        David Sterba <dsterba@...e.com>
Cc:     Arnd Bergmann <arnd@...db.de>, Filipe Manana <fdmanana@...e.com>,
        Anand Jain <anand.jain@...cle.com>,
        Nikolay Borisov <nborisov@...e.com>,
        linux-btrfs@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH] btrfs: shut up bogus -Wmaybe-uninitialized warning

gcc sometimes can't determine whether a variable has been initialized
when both the initialization and the use are conditional:

fs/btrfs/props.c: In function 'inherit_props':
fs/btrfs/props.c:389:4: error: 'num_bytes' may be used uninitialized in this function [-Werror=maybe-uninitialized]
    btrfs_block_rsv_release(fs_info, trans->block_rsv,

This code is fine. Unfortunately, I cannot think of a good way to
rephrase it in a way that makes gcc understand this, so I add
a bogus initialization the way one should not.

Fixes: d7400ee1b476 ("btrfs: use the existing reserved items for our first prop for inheritance")
Signed-off-by: Arnd Bergmann <arnd@...db.de>
---
 fs/btrfs/props.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/btrfs/props.c b/fs/btrfs/props.c
index a9e2e66152ee..9d47ae1cf5b2 100644
--- a/fs/btrfs/props.c
+++ b/fs/btrfs/props.c
@@ -341,7 +341,7 @@ static int inherit_props(struct btrfs_trans_handle *trans,
 	for (i = 0; i < ARRAY_SIZE(prop_handlers); i++) {
 		const struct prop_handler *h = &prop_handlers[i];
 		const char *value;
-		u64 num_bytes;
+		u64 num_bytes = 0;
 
 		if (!h->inheritable)
 			continue;
-- 
2.20.0