ext4: fix smatch warning in move_extent.c's mext_replace_branches()
Commit 2147b1a6a48 resulted in a new smatch warning:
> fs/ext4/move_extent.c:693 mext_replace_branches()
> warn: variable dereferenced before check 'dext' (see line 683)
Fix this by adding a check to make sure dext is non-NULL before we
derefrence it.
Signed-off-by: Akria Fujita <a-fujita@rs.jp.nec.com>
[ modified by tytso to make sure an ext4_error is called ]
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
diff --git a/fs/ext4/move_extent.c b/fs/ext4/move_extent.c
index d9cc5ee..e4cdb51 100644
--- a/fs/ext4/move_extent.c
+++ b/fs/ext4/move_extent.c
@@ -681,6 +681,8 @@
depth = ext_depth(donor_inode);
dext = donor_path[depth].p_ext;
+ if (unlikely(!dext))
+ goto missing_donor_extent;
tmp_dext = *dext;
*err = mext_calc_swap_extents(&tmp_dext, &tmp_oext, orig_off,
@@ -691,7 +693,8 @@
/* Loop for the donor extents */
while (1) {
/* The extent for donor must be found. */
- if (!dext) {
+ if (unlikely(!dext)) {
+ missing_donor_extent:
EXT4_ERROR_INODE(donor_inode,
"The extent for donor must be found");
*err = -EIO;