From 5f04598b386cdf97db226b86a2d0b983198e2194 Mon Sep 17 00:00:00 2001 From: Ni Xun Date: Sat, 22 Oct 2022 15:08:12 +0800 Subject: [PATCH] io_uring: fix async buffered reads when readahead is disabled upstream commit id: c8d317aa1887b40b188ec3aaa6e9e524333caed1 The async buffered reads feature is not working when readahead is turned off. There are two things to concern: - when doing retry in io_read, not only the IOCB_WAITQ flag but also the IOCB_NOWAIT flag is still set, which makes it goes to would_block phase in generic_file_buffered_read() and then return -EAGAIN. After that, the io-wq thread work is queued, and later doing the async reads in the old way. - even if we remove IOCB_NOWAIT when doing retry, the feature is still not running properly, since in generic_file_buffered_read() it goes to lock_page_killable() after calling mapping->a_ops->readpage() to do IO, and thus causing process to sleep. Fixes: 1a0a7853b901 ("mm: support async buffered reads in generic_file_buffered_read()") Fixes: 3b2a4439e0ae ("io_uring: get rid of kiocb_wait_page_queue_init()") Signed-off-by: Hao Xu Signed-off-by: Jens Axboe Signed-off-by: Ni Xun --- mm/filemap.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/mm/filemap.c b/mm/filemap.c index d464f446d..2f7f99bd2 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -2252,7 +2252,11 @@ readpage: } if (!PageUptodate(page)) { - error = lock_page_killable(page); + if (iocb->ki_flags & IOCB_WAITQ) + error = lock_page_async(page, iocb->ki_waitq); + else + error = lock_page_killable(page); + if (unlikely(error)) goto readpage_error; if (!PageUptodate(page)) {