ext4: EXT4_IOC_MOVE_EXT: Check for different original and donor inodes first

Move the check to make sure the original and donor inodes are
different earlier, to avoid a potential deadlock by trying to lock the
same inode twice.

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

diff --git a/fs/ext4/move_extent.c b/fs/ext4/move_extent.c
index 5332fd4c40286cb1ea5d1b52a15ceffd7bf46043..25b6b1457360d2ed1df3ab943a99bac01d4a5e11 100644 (file)
--- a/fs/ext4/move_extent.c
+++ b/fs/ext4/move_extent.c
@@ -1001,14 +1001,6 @@ mext_check_arguments(struct inode *orig_inode,
                return -EINVAL;
        }
 
-       /* orig and donor should be different file */
-       if (orig_inode->i_ino == donor_inode->i_ino) {
-               ext4_debug("ext4 move extent: The argument files should not "
-                       "be same file [ino:orig %lu, donor %lu]\n",
-                       orig_inode->i_ino, donor_inode->i_ino);
-               return -EINVAL;
-       }
-
        /* Ext4 move extent supports only extent based file */
        if (!(EXT4_I(orig_inode)->i_flags & EXT4_EXTENTS_FL)) {
                ext4_debug("ext4 move extent: orig file is not extents "
@@ -1232,6 +1224,14 @@ ext4_move_extents(struct file *o_filp, struct file *d_filp,
        int block_len_in_page;
        int uninit;
 
+       /* orig and donor should be different file */
+       if (orig_inode->i_ino == donor_inode->i_ino) {
+               ext4_debug("ext4 move extent: The argument files should not "
+                       "be same file [ino:orig %lu, donor %lu]\n",
+                       orig_inode->i_ino, donor_inode->i_ino);
+               return -EINVAL;
+       }
+
        /* protect orig and donor against a truncate */
        ret1 = mext_inode_double_lock(orig_inode, donor_inode);
        if (ret1 < 0)