ext4: initialize moved_len before calling ext4_move_extents()

The move_extent.moved_len is used to pass back the number of exchanged
blocks count to user space.  Currently the caller must clear this
field; but we spend more code space checking for this requirement than
simply zeroing the field ourselves, so let's just make life easier for
everyone all around.

Signed-off-by: Kazuya Mio <k-mio@sx.jp.nec.com>
Signed-off-by: Akira Fujita <a-fujita@rs.jp.nec.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

2 files changed, 4 insertions, 11 deletions

diff --git a/fs/ext4/ioctl.c b/fs/ext4/ioctl.c
index c1cdf613e725..31e5ee0c858f 100644
--- a/fs/ext4/ioctl.c
+++ b/fs/ext4/ioctl.c
@@ -239,6 +239,7 @@ setversion_out:
                         }
                 }
 
+                me.moved_len = 0;
                 err = ext4_move_extents(filp, donor_filp, me.orig_start,
                                         me.donor_start, me.len, &me.moved_len);
                 fput(donor_filp);
diff --git a/fs/ext4/move_extent.c b/fs/ext4/move_extent.c
index 3478889e00b3..445ecd7616a6 100644
--- a/fs/ext4/move_extent.c
+++ b/fs/ext4/move_extent.c
@@ -947,7 +947,6 @@ out2:
  * @orig_start:         logical start offset in block for orig
  * @donor_start:        logical start offset in block for donor
  * @len:                the number of blocks to be moved
- * @moved_len:          moved block length
  *
  * Check the arguments of ext4_move_extents() whether the files can be
  * exchanged with each other.
@@ -955,8 +954,8 @@ out2:
  */
 static int
 mext_check_arguments(struct inode *orig_inode,
-                          struct inode *donor_inode, __u64 orig_start,
-                          __u64 donor_start, __u64 *len, __u64 moved_len)
+                     struct inode *donor_inode, __u64 orig_start,
+                     __u64 donor_start, __u64 *len)
 {
         ext4_lblk_t orig_blocks, donor_blocks;
         unsigned int blkbits = orig_inode->i_blkbits;
@@ -1010,13 +1009,6 @@ mext_check_arguments(struct inode *orig_inode,
                 return -EINVAL;
         }
 
-        if (moved_len) {
-                ext4_debug("ext4 move extent: moved_len should be 0 "
-                        "[ino:orig %lu, donor %lu]\n", orig_inode->i_ino,
-                        donor_inode->i_ino);
-                return -EINVAL;
-        }
-
         if ((orig_start > EXT_MAX_BLOCK) ||
             (donor_start > EXT_MAX_BLOCK) ||
             (*len > EXT_MAX_BLOCK) ||
@@ -1226,7 +1218,7 @@ ext4_move_extents(struct file *o_filp, struct file *d_filp,
         double_down_write_data_sem(orig_inode, donor_inode);
         /* Check the filesystem environment whether move_extent can be done */
         ret1 = mext_check_arguments(orig_inode, donor_inode, orig_start,
-                                        donor_start, &len, *moved_len);
+                                    donor_start, &len);
         if (ret1)
                 goto out;