ext4: Fix insertion point of extent in mext_insert_across_blocks()

If the leaf node has 2 extent space or fewer and EXT4_IOC_MOVE_EXT
ioctl is called with the file offset where after the 2nd extent
covers, mext_insert_across_blocks() always tries to insert extent into
the first extent.  As a result, the file gets corrupted because of
wrong extent order.  The patch fixes this problem.

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

1 files changed, 4 insertions, 0 deletions

diff --git a/fs/ext4/move_extent.c b/fs/ext4/move_extent.c
index 1654eb862d74..9eca1c0ec546 100644
--- a/fs/ext4/move_extent.c
+++ b/fs/ext4/move_extent.c
@@ -252,6 +252,7 @@ mext_insert_across_blocks(handle_t *handle, struct inode *orig_inode,
                 }
 
                 o_start->ee_len = start_ext->ee_len;
+                eblock = le32_to_cpu(start_ext->ee_block);
                 new_flag = 1;
 
         } else if (start_ext->ee_len && new_ext->ee_len &&
@@ -262,6 +263,7 @@ mext_insert_across_blocks(handle_t *handle, struct inode *orig_inode,
                  * orig  |------------------------------|
                  */
                 o_start->ee_len = start_ext->ee_len;
+                eblock = le32_to_cpu(start_ext->ee_block);
                 new_flag = 1;
 
         } else if (!start_ext->ee_len && new_ext->ee_len &&
@@ -502,6 +504,7 @@ mext_leaf_block(handle_t *handle, struct inode *orig_inode,
                 le32_to_cpu(oext->ee_block) + oext_alen) {
                 start_ext.ee_len = cpu_to_le16(le32_to_cpu(new_ext.ee_block) -
                                                le32_to_cpu(oext->ee_block));
+                start_ext.ee_block = oext->ee_block;
                 copy_extent_status(oext, &start_ext);
         } else if (oext > EXT_FIRST_EXTENT(orig_path[depth].p_hdr)) {
                 prev_ext = oext - 1;
@@ -515,6 +518,7 @@ mext_leaf_block(handle_t *handle, struct inode *orig_inode,
                         start_ext.ee_len = cpu_to_le16(
                                 ext4_ext_get_actual_len(prev_ext) +
                                 new_ext_alen);
+                        start_ext.ee_block = oext->ee_block;
                         copy_extent_status(prev_ext, &start_ext);
                         new_ext.ee_len = 0;
                 }