Re: [PATCH] Btrfs: work around maybe-uninitialized warning
From: Liu Bo <hidden>
Date: 2017-05-19 18:13:57
Also in:
lkml
On Thu, May 18, 2017 at 03:33:29PM +0200, Arnd Bergmann wrote:
A rewrite of btrfs_submit_direct_hook appears to have introduced a warning:
fs/btrfs/inode.c: In function 'btrfs_submit_direct_hook':
fs/btrfs/inode.c:8467:14: error: 'bio' may be used uninitialized in this function [-Werror=maybe-uninitialized]
Where the 'bio' variable was previously initialized unconditionally, it
is now set in the "while (submit_len > 0)" loop that would never execute
if submit_len is zero.
Assuming this cannot happen in practice, we can avoid the warning
by simply replacing the while{} loop with a do{}while() loop so
the compiler knows that it will always be entered at least once.Thanks for the fix. I think it's a false positve one and I've updated it in v2 with a 'struct bio *bio = NULL' to make compiler happy, could you please help reveiw it? Thanks, -liubo
quoted hunk ↗ jump to hunk
Fixes: 0fd27e06c61b ("Btrfs: use bio_clone_bioset_partial to simplify DIO submit") Signed-off-by: Arnd Bergmann <arnd@arndb.de> --- --- fs/btrfs/inode.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c index 8c37b4fa4cbb..c62cf9593cb3 100644 --- a/fs/btrfs/inode.c +++ b/fs/btrfs/inode.c@@ -8497,7 +8497,7 @@ static int btrfs_submit_direct_hook(struct btrfs_dio_private *dip, /* bio split */ ASSERT(map_length <= INT_MAX); atomic_inc(&dip->pending_bios); - while (submit_len > 0) { + do { clone_len = min_t(int, submit_len, map_length); /*@@ -8540,7 +8540,7 @@ static int btrfs_submit_direct_hook(struct btrfs_dio_private *dip, start_sector << 9, &map_length, NULL, 0); if (ret) goto out_err; - } + } while (submit_len > 0); submit: ret = __btrfs_submit_dio_bio(bio, inode, file_offset, skip_sum,-- 2.9.0