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>

1 files changed, 14 insertions, 15 deletions

diff --git a/fs/ext4/migrate.c b/fs/ext4/migrate.c
index 46a4101e0aec..8b87bd0eac95 100644
--- 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);