[PATCH 3.10 252/268] gfs2: avoid uninitialized variable warning

From: Willy Tarreau
Date: Mon Jun 19 2017 - 15:01:04 EST

From: Arnd Bergmann <arnd@xxxxxxxx>

commit 67893f12e5374bbcaaffbc6e570acbc2714ea884 upstream.

We get a bogus warning about a potential uninitialized variable
use in gfs2, because the compiler does not figure out that we
never use the leaf number if get_leaf_nr() returns an error:

fs/gfs2/dir.c: In function 'get_first_leaf':
fs/gfs2/dir.c:802:9: warning: 'leaf_no' may be used uninitialized in this function [-Wmaybe-uninitialized]
fs/gfs2/dir.c: In function 'dir_split_leaf':
fs/gfs2/dir.c:1021:8: warning: 'leaf_no' may be used uninitialized in this function [-Wmaybe-uninitialized]

Changing the 'if (!error)' to 'if (!IS_ERR_VALUE(error))' is
sufficient to let gcc understand that this is exactly the same
condition as in IS_ERR() so it can optimize the code path enough
to understand it.

Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
Signed-off-by: Bob Peterson <rpeterso@xxxxxxxxxx>
Signed-off-by: Willy Tarreau <w@xxxxxx>
fs/gfs2/dir.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/fs/gfs2/dir.c b/fs/gfs2/dir.c
index b631c90..9aaa6db 100644
--- a/fs/gfs2/dir.c
+++ b/fs/gfs2/dir.c
@@ -763,7 +763,7 @@ static int get_first_leaf(struct gfs2_inode *dip, u32 index,
int error;

error = get_leaf_nr(dip, index, &leaf_no);
- if (!error)
+ if (!IS_ERR_VALUE(error))
error = get_leaf(dip, leaf_no, bh_out);

return error;
@@ -974,7 +974,7 @@ static int dir_split_leaf(struct inode *inode, const struct qstr *name)

index = name->hash >> (32 - dip->i_depth);
error = get_leaf_nr(dip, index, &leaf_no);
- if (error)
+ if (IS_ERR_VALUE(error))
return error;

/* Get the old leaf block */