Hi, For extent-based files, you can perform DIO to holes, as mentioned in the comments in ext4_ext_direct_IO. However, that function passes DIO_SKIP_HOLES to __blockdev_direct_IO, which is *really* confusing to the uninitiated reader. The key, here, is that the get_block function passed in, ext4_get_block_write, completely ignores the create flag that is passed to it (the create flag is passed in from the direct I/O code, which uses the DIO_SKIP_HOLES flag to determine whether or not it should be cleared). This is a long-winded way of saying that the DIO_SKIP_HOLES flag is ultimately ignored. So, in the interest of preserving sanity, I propose the following patch. Cheers, Jeff Signed-off-by: Jeff Moyer <jmoyer@xxxxxxxxxx> diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c index feaa82f..521ca03 100644 --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -2940,7 +2940,7 @@ static ssize_t ext4_ext_direct_IO(int rw, struct kiocb *iocb, ext4_get_block_write, ext4_end_io_dio, NULL, - DIO_LOCKING | DIO_SKIP_HOLES); + DIO_LOCKING); if (iocb->private) EXT4_I(inode)->cur_aio_dio = NULL; /* -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
