f2fs: hide a maybe-uninitialized warning

commit 230436b3ef3fd7d4a1da19edf5e87bb2d74e0fc2 upstream.

gcc is unsure about the use of last_ofs_in_node, which might happen
without a prior initialization:

fs/f2fs//git/arm-soc/fs/f2fs/data.c: In function ‘f2fs_map_blocks’:
fs/f2fs/data.c:799:54: warning: ‘last_ofs_in_node’ may be used uninitialized in this function [-Wmaybe-uninitialized]
   if (prealloc && dn.ofs_in_node != last_ofs_in_node + 1) {

As pointed out by Chao Yu, the code is actually correct as 'prealloc'
is only set if the last_ofs_in_node has been set, the two always
get updated together.

This initializes last_ofs_in_node to dn.ofs_in_node for each
new dnode at the start of the 'next_block' loop, which at that
point is a correct initialization as well. I assume that compilers
that correctly track the contents of the variables and do not
warn about the condition also figure out that they can eliminate
the extra assignment here.

Fixes: 46008c6d4232 ("f2fs: support in batch multi blocks preallocation")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
index 9ae194fd2fdb81cbc54bfed9220da527d6b21a89..14db4b7120214198ee01433b4f77076c71f05729 100644 (file)
--- a/fs/f2fs/data.c
+++ b/fs/f2fs/data.c
@@ -716,7 +716,7 @@ next_dnode:
        }
 
        prealloc = 0;
-       ofs_in_node = dn.ofs_in_node;
+       last_ofs_in_node = ofs_in_node = dn.ofs_in_node;
        end_offset = ADDRS_PER_PAGE(dn.node_page, inode);
 
 next_block: