fs/ntfs3: Keep preallocated only if option prealloc enabled

commit e95113e upstream.

If size of file was reduced, we still kept allocated blocks.
This commit makes ntfs3 work as other fs like btrfs.
Link: https://bugzilla.kernel.org/show_bug.cgi?id=214719
Fixes: 4342306 ("fs/ntfs3: Add file operations and implementation")

Reported-by: Ganapathi Kamath <hgkamath@hotmail.com>
Tested-by: Ganapathi Kamath <hgkamath@hotmail.com>
Reviewed-by: Kari Argillander <kari.argillander@gmail.com>
Signed-off-by: Konstantin Komarov <almaz.alexandrovich@paragon-software.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

fs/ntfs3/file.c

@@ -495,7 +495,7 @@ static int ntfs_truncate(struct inode *inode, loff_t new_size)
 
 	down_write(&ni->file.run_lock);
 	err = attr_set_size(ni, ATTR_DATA, NULL, 0, &ni->file.run, new_size,
-			    &new_valid, true, NULL);
+			    &new_valid, ni->mi.sbi->options->prealloc, NULL);
 	up_write(&ni->file.run_lock);
 
 	if (new_valid < ni->i_valid)