Re: [RFC PATCH v2 3/5] mm: Make swap_readpage() for SWP_FS_OPS use ->direct_IO() not ->readpage()
From: Matthew Wilcox <willy@infradead.org>
Date: 2021-08-12 21:25:59
Also in:
linux-fsdevel, linux-nfs, lkml
On Thu, Aug 12, 2021 at 09:22:24PM +0100, David Howells wrote:
quoted hunk ↗ jump to hunk
+++ 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?