On 09/17/2015 10:24 PM, Sasha Levin wrote: > On 08/19/2015 01:46 AM, Al Viro wrote: >>> or mapping->a_ops->direct_IO() returned more >>>> than 'count'. >> Was there DAX involved? ->direct_IO() in there is blkdev_direct_IO(), >> which takes rather different paths in those cases... >> > > So I've traced this all the way back to dax_io(). I can trigger this with: > > diff --git a/fs/dax.c b/fs/dax.c > index 93bf2f9..2cdb8a5 100644 > --- a/fs/dax.c > +++ b/fs/dax.c > @@ -178,6 +178,7 @@ static ssize_t dax_io(struct inode *inode, struct iov_iter *iter, > if (need_wmb) > wmb_pmem(); > > + WARN_ON((pos == start) && (pos - start > iov_iter_count(iter))); > return (pos == start) ? retval : pos - start; > } > > So it seems that iter gets moved twice here: once in dax_io(), and once again > back at generic_file_read_iter(). > > I don't see how it ever worked. Am I missing something? Ping? Thanks, Sasha -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
