On Tue 14-01-20 10:27:36, Christoph Hellwig wrote: > On Tue, Jan 14, 2020 at 06:19:34PM +0100, Jan Kara wrote: > > We want to detect in the writeback path whether there's direct IO (read) > > currently running for the inode. Not for the writeback issued from > > iomap_dio_rw() but for any arbitrary writeback that iomap_dio_rw() can be > > racing with - so struct writeback_control won't help. Now if you want to > > see the ugly details why this hack is needed, see my other email to Ritesh > > in this thread with details of the race. > > How do we get other writeback after iomap_dio_rw wrote everything out? You create dirty page using mmap in the range read by iomap_dio_rw() and then background writeback happens at unfortunate time... Email [1] has the exact traces. > Either way I'm trying to kill i_dio_count as it has all kinds of > problems, see the patch sent out earlier today. OK, I'll see that patch. Honza [1] https://lore.kernel.org/linux-ext4/20200114094741.GC6466@xxxxxxxxxxxxxx -- Jan Kara <jack@xxxxxxxx> SUSE Labs, CR
