Messages in this thread | | | Date | Thu, 12 Aug 2021 22:23:46 +0100 | From | Matthew Wilcox <> | Subject | Re: [RFC PATCH v2 3/5] mm: Make swap_readpage() for SWP_FS_OPS use ->direct_IO() not ->readpage() |
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On Thu, Aug 12, 2021 at 09:22:24PM +0100, David Howells wrote: > +++ b/include/linux/fs.h > @@ -336,6 +336,7 @@ struct kiocb { > union { > unsigned int ki_cookie; /* for ->iopoll */ > struct wait_page_queue *ki_waitq; /* for async buffered IO */ > + struct page *ki_swap_page; /* For swapfile_read/write */
Nice idea.
> +static void __swapfile_read_complete(struct kiocb *iocb, long ret, long ret2)
I would make this take a struct page * and just one 'ret'.
> +{ > + struct page *page = iocb->ki_swap_page; > + > + if (ret == PAGE_SIZE) {
page_size(page)?
> + kiocb.ki_pos = page_file_offset(page);
We talked about swap_file_pos(), right?
> + ret = swap_file->f_mapping->a_ops->direct_IO(&kiocb, &to); > + > + __swapfile_read_complete(&kiocb, ret, 0); > + return (ret > 0) ? 0 : ret;
What if it returns a short read?
> +static int swapfile_read(struct swap_info_struct *sis, struct page *page, > + bool synchronous) > +{ > + struct swapfile_kiocb *ki; > + struct file *swap_file = sis->swap_file; > + struct bio_vec bv = { > + .bv_page = page, > + .bv_len = thp_size(page), > + .bv_offset = 0 > + }; > + struct iov_iter to; > + int ret; > + > + if (synchronous) > + return swapfile_read_sync(sis, page);
Seems a shame to set up the bio_vec and iov_iter twice. Maybe call:
iov_iter_bvec(&to, READ, &bv, 1, thp_size(page));
before swapfile_read_sync() and pass a pointer to 'to' to swapfile_read_sync?
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