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btrfs: fix uninitialized variable access after ASSERT

Message ID 20161128210606.2321419-1-arnd@arndb.de
State New
Headers show

Commit Message

Arnd Bergmann Nov. 28, 2016, 9:05 p.m. UTC 
In btrfs, ASSERT() has no effect if CONFIG_BTRFS_ASSERT is disabled,
and gcc notices that this can lead to using an uninitialized variable:

fs/btrfs/inode.c: In function 'run_delalloc_range':
fs/btrfs/inode.c:1190:18: error: 'cur_end' may be used uninitialized in this function [-Werror=maybe-uninitialized]

I assume the condition that the ASSERT checks for is actually
correct and we won't get there in practice, but it's easy to
modify the function to make it simpler and avoid the condition
that the warning is for.

Fixes: e5249f75cfd0 ("btrfs: Introduce COMPRESS reserve type to fix false enospc for compression")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

---
 fs/btrfs/inode.c | 8 ++------
 1 file changed, 2 insertions(+), 6 deletions(-)

-- 
2.9.0
diff mbox

Patch

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index e6f35d923d67..b1d2b38d29aa 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -1175,18 +1175,14 @@  static int cow_file_range_async(struct inode *inode, struct page *locked_page,
 	clear_extent_bit(&BTRFS_I(inode)->io_tree, start, end, EXTENT_LOCKED,
 			 1, 0, NULL, GFP_NOFS);
 	while (start < end) {
+		ASSERT(reserve_type == BTRFS_RESERVE_COMPRESS);
 		async_cow = kmalloc(sizeof(*async_cow), GFP_NOFS);
 		BUG_ON(!async_cow); /* -ENOMEM */
 		async_cow->inode = igrab(inode);
 		async_cow->root = root;
 		async_cow->locked_page = locked_page;
 		async_cow->start = start;
-
-		if (reserve_type == BTRFS_RESERVE_COMPRESS)
-			cur_end = min(end, start + SZ_512K - 1);
-		else
-			ASSERT(0);
-
+		cur_end = min(end, start + SZ_512K - 1);
 		async_cow->end = cur_end;
 		INIT_LIST_HEAD(&async_cow->extents);