On Tue 22-01-13 22:22:21, Zheng Liu wrote: > On Tue, Jan 22, 2013 at 02:44:00PM +0100, Jan Kara wrote: > > On Tue 22-01-13 15:11:24, Dmitry Monakhov wrote: > > > On Fri, 18 Jan 2013 13:00:37 +0100, Jan Kara <jack@xxxxxxx> wrote: > > > > When using indirect blocks there is no possibility to have any unwritten > > > > extents. So wait for them in ext4_ind_direct_IO() is just bogus. > > > But as soon as i remember indirect implementation may also be used by > > > extents based inodes 3074: ext4_ext_direct_IO > > > /* Use the old path for reads and writes beyond i_size. */ > > > if (rw != WRITE || final_size > inode->i_size) > > > return ext4_ind_direct_IO(rw, iocb, iov, offset, nr_segs); > > > > > > Am I missing ? > > Ah, that's a catch. Thanks for pointing that out! So my patch is wrong > > and that code path needs some cleaning and commenting. In particular I'm > > afraid using dioread_nolock for inodes with indirect map causes data > > exposure bugs when unlocked DIO read races with DIO write because such > > inodes don't support uninitialized extents. > > Sorry, but I am still confused. dioread_nolock is only for extent-based > file. So when a file system without extent feature, dioread_nolock > couldn't be enabled. It seems that we don't need to worry about > exposing stale data here. Well, you can have fs with extent feature enabled but still with inodes using indirect map. But as Dmitry pointed out, ext4_should_dioread_nolock() handles that correctly. So there's not a bug I was suspecting. Honza -- Jan Kara <jack@xxxxxxx> SUSE Labs, CR -- 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
