From ab50533b6946b1adeb8eef62c6b16689abcd1e70 Mon Sep 17 00:00:00 2001 From: Emanuele Giuseppe Esposito Date: Fri, 3 Feb 2023 08:17:28 -0500 Subject: [PATCH] linux-aio: use LinuxAioState from the running thread Remove usage of aio_context_acquire by always submitting asynchronous AIO to the current thread's LinuxAioState. In order to prevent mistakes from the caller side, avoid passing LinuxAioState in laio_io_{plug/unplug} and laio_co_submit, and document the functions to make clear that they work in the current thread's AioContext. Signed-off-by: Emanuele Giuseppe Esposito Message-Id: <20230203131731.851116-2-eesposit@redhat.com> Reviewed-by: Kevin Wolf Reviewed-by: Stefan Hajnoczi Signed-off-by: Kevin Wolf --- block/file-posix.c | 10 +++------- block/linux-aio.c | 29 +++++++++++++++++------------ include/block/aio.h | 4 ---- include/block/raw-aio.h | 18 ++++++++++++------ include/sysemu/block-backend-io.h | 5 +++++ 5 files changed, 37 insertions(+), 29 deletions(-) diff --git a/block/file-posix.c b/block/file-posix.c index c2dee3f056..1b4342822b 100644 --- a/block/file-posix.c +++ b/block/file-posix.c @@ -2095,10 +2095,8 @@ static int coroutine_fn raw_co_prw(BlockDriverState *bs, uint64_t offset, #endif #ifdef CONFIG_LINUX_AIO } else if (s->use_linux_aio) { - LinuxAioState *aio = aio_get_linux_aio(bdrv_get_aio_context(bs)); assert(qiov->size == bytes); - return laio_co_submit(bs, aio, s->fd, offset, qiov, type, - s->aio_max_batch); + return laio_co_submit(s->fd, offset, qiov, type, s->aio_max_batch); #endif } @@ -2137,8 +2135,7 @@ static void coroutine_fn raw_co_io_plug(BlockDriverState *bs) BDRVRawState __attribute__((unused)) *s = bs->opaque; #ifdef CONFIG_LINUX_AIO if (s->use_linux_aio) { - LinuxAioState *aio = aio_get_linux_aio(bdrv_get_aio_context(bs)); - laio_io_plug(bs, aio); + laio_io_plug(); } #endif #ifdef CONFIG_LINUX_IO_URING @@ -2154,8 +2151,7 @@ static void coroutine_fn raw_co_io_unplug(BlockDriverState *bs) BDRVRawState __attribute__((unused)) *s = bs->opaque; #ifdef CONFIG_LINUX_AIO if (s->use_linux_aio) { - LinuxAioState *aio = aio_get_linux_aio(bdrv_get_aio_context(bs)); - laio_io_unplug(bs, aio, s->aio_max_batch); + laio_io_unplug(s->aio_max_batch); } #endif #ifdef CONFIG_LINUX_IO_URING diff --git a/block/linux-aio.c b/block/linux-aio.c index d2cfb7f523..fc50cdd1bf 100644 --- a/block/linux-aio.c +++ b/block/linux-aio.c @@ -16,6 +16,9 @@ #include "qemu/coroutine.h" #include "qapi/error.h" +/* Only used for assertions. */ +#include "qemu/coroutine_int.h" + #include /* @@ -56,10 +59,8 @@ struct LinuxAioState { io_context_t ctx; EventNotifier e; - /* io queue for submit at batch. Protected by AioContext lock. */ + /* No locking required, only accessed from AioContext home thread */ LaioQueue io_q; - - /* I/O completion processing. Only runs in I/O thread. */ QEMUBH *completion_bh; int event_idx; int event_max; @@ -102,6 +103,7 @@ static void qemu_laio_process_completion(struct qemu_laiocb *laiocb) * later. Coroutines cannot be entered recursively so avoid doing * that! */ + assert(laiocb->co->ctx == laiocb->ctx->aio_context); if (!qemu_coroutine_entered(laiocb->co)) { aio_co_wake(laiocb->co); } @@ -232,13 +234,11 @@ static void qemu_laio_process_completions(LinuxAioState *s) static void qemu_laio_process_completions_and_submit(LinuxAioState *s) { - aio_context_acquire(s->aio_context); qemu_laio_process_completions(s); if (!s->io_q.plugged && !QSIMPLEQ_EMPTY(&s->io_q.pending)) { ioq_submit(s); } - aio_context_release(s->aio_context); } static void qemu_laio_completion_bh(void *opaque) @@ -354,14 +354,19 @@ static uint64_t laio_max_batch(LinuxAioState *s, uint64_t dev_max_batch) return max_batch; } -void laio_io_plug(BlockDriverState *bs, LinuxAioState *s) +void laio_io_plug(void) { + AioContext *ctx = qemu_get_current_aio_context(); + LinuxAioState *s = aio_get_linux_aio(ctx); + s->io_q.plugged++; } -void laio_io_unplug(BlockDriverState *bs, LinuxAioState *s, - uint64_t dev_max_batch) +void laio_io_unplug(uint64_t dev_max_batch) { + AioContext *ctx = qemu_get_current_aio_context(); + LinuxAioState *s = aio_get_linux_aio(ctx); + assert(s->io_q.plugged); s->io_q.plugged--; @@ -411,15 +416,15 @@ static int laio_do_submit(int fd, struct qemu_laiocb *laiocb, off_t offset, return 0; } -int coroutine_fn laio_co_submit(BlockDriverState *bs, LinuxAioState *s, int fd, - uint64_t offset, QEMUIOVector *qiov, int type, - uint64_t dev_max_batch) +int coroutine_fn laio_co_submit(int fd, uint64_t offset, QEMUIOVector *qiov, + int type, uint64_t dev_max_batch) { int ret; + AioContext *ctx = qemu_get_current_aio_context(); struct qemu_laiocb laiocb = { .co = qemu_coroutine_self(), .nbytes = qiov->size, - .ctx = s, + .ctx = aio_get_linux_aio(ctx), .ret = -EINPROGRESS, .is_read = (type == QEMU_AIO_READ), .qiov = qiov, diff --git a/include/block/aio.h b/include/block/aio.h index 543717f294..9e53aabba6 100644 --- a/include/block/aio.h +++ b/include/block/aio.h @@ -208,10 +208,6 @@ struct AioContext { struct ThreadPool *thread_pool; #ifdef CONFIG_LINUX_AIO - /* - * State for native Linux AIO. Uses aio_context_acquire/release for - * locking. - */ struct LinuxAioState *linux_aio; #endif #ifdef CONFIG_LINUX_IO_URING diff --git a/include/block/raw-aio.h b/include/block/raw-aio.h index f8cda9df91..db614472e6 100644 --- a/include/block/raw-aio.h +++ b/include/block/raw-aio.h @@ -49,14 +49,20 @@ typedef struct LinuxAioState LinuxAioState; LinuxAioState *laio_init(Error **errp); void laio_cleanup(LinuxAioState *s); -int coroutine_fn laio_co_submit(BlockDriverState *bs, LinuxAioState *s, int fd, - uint64_t offset, QEMUIOVector *qiov, int type, - uint64_t dev_max_batch); + +/* laio_co_submit: submit I/O requests in the thread's current AioContext. */ +int coroutine_fn laio_co_submit(int fd, uint64_t offset, QEMUIOVector *qiov, + int type, uint64_t dev_max_batch); + void laio_detach_aio_context(LinuxAioState *s, AioContext *old_context); void laio_attach_aio_context(LinuxAioState *s, AioContext *new_context); -void laio_io_plug(BlockDriverState *bs, LinuxAioState *s); -void laio_io_unplug(BlockDriverState *bs, LinuxAioState *s, - uint64_t dev_max_batch); + +/* + * laio_io_plug/unplug work in the thread's current AioContext, therefore the + * caller must ensure that they are paired in the same IOThread. + */ +void laio_io_plug(void); +void laio_io_unplug(uint64_t dev_max_batch); #endif /* io_uring.c - Linux io_uring implementation */ #ifdef CONFIG_LINUX_IO_URING diff --git a/include/sysemu/block-backend-io.h b/include/sysemu/block-backend-io.h index bb25493ba1..851a44de96 100644 --- a/include/sysemu/block-backend-io.h +++ b/include/sysemu/block-backend-io.h @@ -90,6 +90,11 @@ void blk_iostatus_set_err(BlockBackend *blk, int error); int blk_get_max_iov(BlockBackend *blk); int blk_get_max_hw_iov(BlockBackend *blk); +/* + * blk_io_plug/unplug are thread-local operations. This means that multiple + * IOThreads can simultaneously call plug/unplug, but the caller must ensure + * that each unplug() is called in the same IOThread of the matching plug(). + */ void coroutine_fn blk_co_io_plug(BlockBackend *blk); void co_wrapper blk_io_plug(BlockBackend *blk); -- 2.11.0