ext4: Automatically allocate delay allocated blocks on close

When closing a file that had been previously truncated, force any
delay allocated blocks that to be allocated so that if the filesystem
is mounted with data=ordered, the data blocks will be pushed out to
disk along with the journal commit.  Many application programs expect
this, so we do this to avoid zero length files if the system crashes
unexpectedly.

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

1 files changed, 3 insertions, 0 deletions

diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 8dd3d5de5861..80ed6dc9c9d2 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -3901,6 +3901,9 @@ void ext4_truncate(struct inode *inode)
         if (!ext4_can_truncate(inode))
                 return;
 
+        if (inode->i_size == 0)
+                ei->i_state |= EXT4_STATE_DA_ALLOC_CLOSE;
+
         if (EXT4_I(inode)->i_flags & EXT4_EXTENTS_FL) {
                 ext4_ext_truncate(inode);
                 return;