NTFS: Drop the runlist lock after the vcn has been read in

      fs/ntfs/lcnalloc.c::__ntfs_cluster_free().
Signed-off-by: Anton Altaparmakov <aia21@cantab.net>

fs/ntfs/ChangeLog

@@ -70,6 +70,8 @@ ToDo/Notes:
 	  error handling code path that resulted in a BUG() due to trying to
 	  unmap an extent mft record when the mapping of it had failed and it
 	  thus was not mapped.  (Thanks to Ken MacFerrin for the bug report.)
+	- Drop the runlist lock after the vcn has been read in
+	  fs/ntfs/lcnalloc.c::__ntfs_cluster_free().
 
 2.1.21 - Fix some races and bugs, rewrite mft write code, add mft allocator.
 

fs/ntfs/lcnalloc.c

@@ -903,8 +903,8 @@ s64 __ntfs_cluster_free(struct inode *vi, const VCN start_vcn, s64 count,
 			 * Attempt to map runlist, dropping runlist lock for
 			 * the duration.
 			 */
-			up_read(&ni->runlist.lock);
 			vcn = rl->vcn;
+			up_read(&ni->runlist.lock);
 			err = ntfs_map_runlist(ni, vcn);
 			if (err) {
 				if (!is_rollback)