ext4: fix incorrect lock ordering for ext4_ind_migrate

existing locking ordering: journal-> i_data_sem, but
ext4_ind_migrate() grab locks in opposite order which may result in
deadlock.

Signed-off-by: Dmitry Monakhov <dmonakhov@openvz.org>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index 6c5a70a7b5736969c9c3e69b8f65fa73ccc2949a..ea607f9072323e486df70ccb4c2c6597bff09aed 100644 (file)
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -4735,6 +4735,10 @@ int ext4_ind_migrate(struct inode *inode)
            (!ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)))
                return -EINVAL;
 
+       handle = ext4_journal_start(inode, EXT4_HT_MIGRATE, 1);
+       if (IS_ERR(handle))
+               return PTR_ERR(handle);
+
        down_write(&EXT4_I(inode)->i_data_sem);
        ret = ext4_ext_check_inode(inode);
        if (ret)
@@ -4758,19 +4762,13 @@ int ext4_ind_migrate(struct inode *inode)
                }
        }
 
-       handle = ext4_journal_start(inode, EXT4_HT_MIGRATE, 1);
-       if (IS_ERR(handle)) {
-               ret = PTR_ERR(handle);
-               goto errout;
-       }
-
        ext4_clear_inode_flag(inode, EXT4_INODE_EXTENTS);
        memset(ei->i_data, 0, sizeof(ei->i_data));
        for (i=0; i < len; i++)
                ei->i_data[i] = cpu_to_le32(blk++);
        ext4_mark_inode_dirty(handle, inode);
-       ext4_journal_stop(handle);
 errout:
+       ext4_journal_stop(handle);
        up_write(&EXT4_I(inode)->i_data_sem);
        return ret;
 }