| Message ID | 1601380845-206925-1-git-send-email-haoxu@linux.alibaba.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | io_uring: support async buffered reads when readahead is disabled | expand |
On 9/29/20 6:00 AM, Hao Xu wrote: > 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. Thanks, this looks great, and avoids cases of io-wq punt where we don't need it. I'm going to run this through full testing, but I think this looks good to me.
diff --git a/fs/io_uring.c b/fs/io_uring.c index 556e4a2ead07..e7e8ea58274e 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -3106,6 +3106,7 @@ static bool io_rw_should_retry(struct io_kiocb *req) wait->wait.flags = 0; INIT_LIST_HEAD(&wait->wait.entry); kiocb->ki_flags |= IOCB_WAITQ; + kiocb->ki_flags &= ~IOCB_NOWAIT; kiocb->ki_waitq = wait; io_get_req_task(req); diff --git a/mm/filemap.c b/mm/filemap.c index 1aaea26556cc..ea383478fc22 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -2267,7 +2267,11 @@ ssize_t generic_file_buffered_read(struct kiocb *iocb, } 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)) {
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 <haoxu@linux.alibaba.com> --- fs/io_uring.c | 1 + mm/filemap.c | 6 +++++- 2 files changed, 6 insertions(+), 1 deletion(-)