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>

1 files changed, 5 insertions, 7 deletions

diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index 6c5a70a7b573..ea607f907232 100644
--- 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;
 }