ext4: fix error handling in migrate

Set i_nlink to zero for temporary inode from very beginning.
otherwise we may fail to start new journal handle and this
inode will be unreferenced but with i_nlink == 1
Since we hold inode reference it can not be pruned.

Also add missed journal_start retval check.

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

diff --git a/fs/ext4/migrate.c b/fs/ext4/migrate.c
index 46a4101..8b87bd0 100644 (file)
--- a/fs/ext4/migrate.c
+++ b/fs/ext4/migrate.c
@@ -503,14 +503,10 @@ int ext4_ext_migrate(struct inode *inode)
        }
        i_size_write(tmp_inode, i_size_read(inode));
        /*
-        * We don't want the inode to be reclaimed
-        * if we got interrupted in between. We have
-        * this tmp inode carrying reference to the
-        * data blocks of the original file. We set
-        * the i_nlink to zero at the last stage after
-        * switching the original file to extent format
+        * Set the i_nlink to zero so it will be deleted later
+        * when we drop inode reference.
         */
-       tmp_inode->i_nlink = 1;
+       tmp_inode->i_nlink = 0;
 
        ext4_ext_tree_init(handle, tmp_inode);
        ext4_orphan_add(handle, tmp_inode);
@@ -537,6 +533,16 @@ int ext4_ext_migrate(struct inode *inode)
        up_read((&EXT4_I(inode)->i_data_sem));
 
        handle = ext4_journal_start(inode, 1);
+       if (IS_ERR(handle)) {
+               /*
+                * It is impossible to update on-disk structures without
+                * a handle, so just rollback in-core changes and live other
+                * work to orphan_list_cleanup()
+                */
+               ext4_orphan_del(NULL, tmp_inode);
+               retval = PTR_ERR(handle);
+               goto out;
+       }
 
        ei = EXT4_I(inode);
        i_data = ei->i_data;
@@ -618,15 +624,8 @@ err_out:
 
        /* Reset the extent details */
        ext4_ext_tree_init(handle, tmp_inode);
-
-       /*
-        * Set the i_nlink to zero so that
-        * generic_drop_inode really deletes the
-        * inode
-        */
-       tmp_inode->i_nlink = 0;
-
        ext4_journal_stop(handle);
+out:
        unlock_new_inode(tmp_inode);
        iput(tmp_inode);