linux-kernel - [PATCH 5.3 062/163] btrfs: silence maybe-uninitialized warning in clone

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Message-Id: <20191104212144.521512803@linuxfoundation.org>
Date:   Mon,  4 Nov 2019 22:44:12 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Austin Kim <austindh.kim@...il.com>,
        David Sterba <dsterba@...e.com>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.3 062/163] btrfs: silence maybe-uninitialized warning in clone_range

From: Austin Kim <austindh.kim@...il.com>

[ Upstream commit 431d39887d6273d6d84edf3c2eab09f4200e788a ]

GCC throws warning message as below:

‘clone_src_i_size’ may be used uninitialized in this function
[-Wmaybe-uninitialized]
 #define IS_ALIGNED(x, a)  (((x) & ((typeof(x))(a) - 1)) == 0)
                       ^
fs/btrfs/send.c:5088:6: note: ‘clone_src_i_size’ was declared here
 u64 clone_src_i_size;
   ^
The clone_src_i_size is only used as call-by-reference
in a call to get_inode_info().

Silence the warning by initializing clone_src_i_size to 0.

Note that the warning is a false positive and reported by older versions
of GCC (eg. 7.x) but not eg 9.x. As there have been numerous people, the
patch is applied. Setting clone_src_i_size to 0 does not otherwise make
sense and would not do any action in case the code changes in the future.

Signed-off-by: Austin Kim <austindh.kim@...il.com>
Reviewed-by: David Sterba <dsterba@...e.com>
[ add note ]
Signed-off-by: David Sterba <dsterba@...e.com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 fs/btrfs/send.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/btrfs/send.c b/fs/btrfs/send.c
index c3c0c064c25da..91c702b4cae9d 100644
--- a/fs/btrfs/send.c
+++ b/fs/btrfs/send.c
@@ -5070,7 +5070,7 @@ static int clone_range(struct send_ctx *sctx,
 	struct btrfs_path *path;
 	struct btrfs_key key;
 	int ret;
-	u64 clone_src_i_size;
+	u64 clone_src_i_size = 0;
 
 	/*
 	 * Prevent cloning from a zero offset with a length matching the sector
-- 
2.20.1