| Message ID | 20220609164712.1539045-2-stefanha@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | linux-aio: fix unbalanced plugged counter in laio_io_unplug() | expand |
On Thu, Jun 09, 2022 at 05:47:11PM +0100, Stefan Hajnoczi wrote: >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. > We can add a Fixes tag: Fixes: 68d7946648 ("linux-aio: add `dev_max_batch` parameter to laio_io_unplug()") >Reported-by: Nikolay Tenev <nt@storpool.com> >Cc: Stefano Garzarella <sgarzare@redhat.com> >Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com> >--- > 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 4c423fcccf..6078da7e42 100644 >--- a/block/linux-aio.c >+++ b/block/linux-aio.c >@@ -363,8 +363,10 @@ 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); > } >-- >2.36.1 > Thanks for fixing this issue! Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
diff --git a/block/linux-aio.c b/block/linux-aio.c index 4c423fcccf..6078da7e42 100644 --- a/block/linux-aio.c +++ b/block/linux-aio.c @@ -363,8 +363,10 @@ 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); }
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 <nt@storpool.com> Cc: Stefano Garzarella <sgarzare@redhat.com> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com> --- block/linux-aio.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)