From 96faf869b9109de54761b0b6c9a29716803f01fb Mon Sep 17 00:00:00 2001 From: wangfuqiang49 Date: Wed, 19 Feb 2025 21:34:43 -0600 Subject: [PATCH] linux-aio: fix unbalanced plugged counter in laio_io_unplug() When the io_submit() in the execution flow of laio_do_submit -> ioq_submit -> io_submit returns an error, such as returning -EAGAIN, s->io_q.blocked will set to 1. Consequently, s->io_q.in_queue may grow to laio_max_batch(), which prevents laio_io_unplug() from decrementing s->io_q.plugged. This situation can cause laio_do_submit() and laio_io_unplug to stop submitting AIO requests unless the number of requests in the queue reaches laio_max_batch(). upstream commit: commit 18bcfa0ebb39146cc4f7dad0dd989a24c74677d9 Author: Stefan Hajnoczi Date: Thu Jun 9 17:47:11 2022 +0100 linux-aio: fix unbalanced plugged counter in laio_io_unplug() Every laio_io_plug() call has a matching laio_io_unplug() call. There is a plugged counter that tracks the number of levels of plugging and allows for nesting. The plugged counter must reflect the balance between laio_io_plug() and laio_io_unplug() calls accurately. Otherwise I/O stalls occur since io_submit(2) calls are skipped while plugged. Reported-by: Nikolay Tenev Signed-off-by: Stefan Hajnoczi Reviewed-by: Stefano Garzarella Message-id: 20220609164712.1539045-2-stefanha@redhat.com Cc: Stefano Garzarella Fixes: 68d7946648 ("linux-aio: add `dev_max_batch` parameter to laio_io_unplug()") [Stefano Garzarella suggested adding a Fixes tag. --Stefan] Signed-off-by: Stefan Hajnoczi --- block/linux-aio.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/block/linux-aio.c b/block/linux-aio.c index f53ae72e21..77f17ad596 100644 --- a/block/linux-aio.c +++ b/block/linux-aio.c @@ -360,8 +360,10 @@ void laio_io_unplug(BlockDriverState *bs, LinuxAioState *s, uint64_t dev_max_batch) { assert(s->io_q.plugged); + s->io_q.plugged--; + if (s->io_q.in_queue >= laio_max_batch(s, dev_max_batch) || - (--s->io_q.plugged == 0 && + (!s->io_q.plugged && !s->io_q.blocked && !QSIMPLEQ_EMPTY(&s->io_q.pending))) { ioq_submit(s); } -- Gitee