Btrfs: work around maybe-uninitialized warning

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.

Fixes changes introduced in "Btrfs: use bio_clone_bioset_partial to
simplify DIO submit".

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 53f2cf4b24b6b10b130a2a976d6e841456b18f3b..93f1b31199d245f0c481dbe3564bcdce31b9b8f5 100644 (file)
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -8507,7 +8507,7 @@ 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);
 
                /*
@@ -8550,7 +8550,7 @@ 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,