ext3: Add replace-on-rename hueristics for data=writeback mode

In data=writeback mode, start an asynchronous flush when renaming a
file on top of an already-existing file.  This lowers the probability
of data loss in the case of applications that attempt to replace a
file via using rename().

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

1 files changed, 5 insertions, 1 deletions

diff --git a/fs/ext3/namei.c b/fs/ext3/namei.c
index 4db4ffa1edad..ab98a66ab8c7 100644
--- a/fs/ext3/namei.c
+++ b/fs/ext3/namei.c
@@ -2265,7 +2265,7 @@ static int ext3_rename (struct inode * old_dir, struct dentry *old_dentry,
         struct inode * old_inode, * new_inode;
         struct buffer_head * old_bh, * new_bh, * dir_bh;
         struct ext3_dir_entry_2 * old_de, * new_de;
-        int retval;
+        int retval, flush_file = 0;
 
         old_bh = new_bh = dir_bh = NULL;
 
@@ -2401,6 +2401,8 @@ static int ext3_rename (struct inode * old_dir, struct dentry *old_dentry,
                 ext3_mark_inode_dirty(handle, new_inode);
                 if (!new_inode->i_nlink)
                         ext3_orphan_add(handle, new_inode);
+                if (ext3_should_writeback_data(new_inode))
+                        flush_file = 1;
         }
         retval = 0;
 
@@ -2409,6 +2411,8 @@ end_rename:
         brelse (old_bh);
         brelse (new_bh);
         ext3_journal_stop(handle);
+        if (retval == 0 && flush_file)
+                filemap_flush(old_inode->i_mapping);
         return retval;
 }