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M . Jones" , Ilya Dryomov , Peter Lieven , =?UTF-8?q?Philippe=20Mathieu-Daud=C3=A9?= , =?UTF-8?q?Alex=20Benn=C3=A9e?= , Fam Zheng , Ronnie Sahlberg Subject: [PATCH v2 04/19] =?UTF-8?q?nfs:=20Run=20co=20BH=20CB=20in=20the?= =?UTF-8?q?=20coroutine=E2=80=99s=20AioContext?= Date: Mon, 10 Nov 2025 16:48:39 +0100 Message-ID: <20251110154854.151484-5-hreitz@redhat.com> X-Mailer: git-send-email 2.51.1 In-Reply-To: <20251110154854.151484-1-hreitz@redhat.com> References: <20251110154854.151484-1-hreitz@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Received-SPF: pass client-ip=170.10.129.124; envelope-from=hreitz@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H3=0.001, RCVD_IN_MSPIKE_WL=0.001, RCVD_IN_VALIDITY_CERTIFIED_BLOCKED=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, SPF_HELO_PASS=-0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: qemu-devel-bounces+importer=patchew.org@nongnu.org X-ZohoMail-DKIM: pass (identity @redhat.com) X-ZM-MESSAGEID: 1762789854452158501 Like in =E2=80=9Crbd: Run co BH CB in the coroutine=E2=80=99s AioContext=E2= =80=9D, drop the completion flag, yield exactly once, and run the BH in the coroutine=E2=80= =99s AioContext. (Can be reproduced with multiqueue by adding a usleep(100000) before the `while (!task.complete)` loops.) Like in =E2=80=9Ciscsi: Run co BH CB in the coroutine=E2=80=99s AioContext= =E2=80=9D, this makes nfs_co_generic_bh_cb() trivial, so we can drop it in favor of just calling aio_co_wake() directly. Cc: qemu-stable@nongnu.org Signed-off-by: Hanna Czenczek --- block/nfs.c | 41 ++++++++++++++++------------------------- 1 file changed, 16 insertions(+), 25 deletions(-) diff --git a/block/nfs.c b/block/nfs.c index 0a7d38db09..1d3a34a30c 100644 --- a/block/nfs.c +++ b/block/nfs.c @@ -69,7 +69,6 @@ typedef struct NFSClient { typedef struct NFSRPC { BlockDriverState *bs; int ret; - int complete; QEMUIOVector *iov; struct stat *st; Coroutine *co; @@ -230,14 +229,6 @@ static void coroutine_fn nfs_co_init_task(BlockDriverS= tate *bs, NFSRPC *task) }; } =20 -static void nfs_co_generic_bh_cb(void *opaque) -{ - NFSRPC *task =3D opaque; - - task->complete =3D 1; - aio_co_wake(task->co); -} - /* Called (via nfs_service) with QemuMutex held. */ static void nfs_co_generic_cb(int ret, struct nfs_context *nfs, void *data, @@ -256,8 +247,16 @@ nfs_co_generic_cb(int ret, struct nfs_context *nfs, vo= id *data, if (task->ret < 0) { error_report("NFS Error: %s", nfs_get_error(nfs)); } - replay_bh_schedule_oneshot_event(task->client->aio_context, - nfs_co_generic_bh_cb, task); + + /* + * Safe to call: nfs_service(), which called us, is only run from the = FD + * handlers, never from the request coroutine. The request coroutine = in + * turn will yield unconditionally. + * No need to release the lock, even if we directly enter the coroutin= e, as + * the lock is never re-taken after yielding. (Note: If we do enter t= he + * coroutine, @task will probably be dangling once aio_co_wake() retur= ns.) + */ + aio_co_wake(task->co); } =20 static int coroutine_fn nfs_co_preadv(BlockDriverState *bs, int64_t offset, @@ -278,9 +277,7 @@ static int coroutine_fn nfs_co_preadv(BlockDriverState = *bs, int64_t offset, =20 nfs_set_events(client); } - while (!task.complete) { - qemu_coroutine_yield(); - } + qemu_coroutine_yield(); =20 if (task.ret < 0) { return task.ret; @@ -328,9 +325,7 @@ static int coroutine_fn nfs_co_pwritev(BlockDriverState= *bs, int64_t offset, =20 nfs_set_events(client); } - while (!task.complete) { - qemu_coroutine_yield(); - } + qemu_coroutine_yield(); =20 if (my_buffer) { g_free(buf); @@ -358,9 +353,7 @@ static int coroutine_fn nfs_co_flush(BlockDriverState *= bs) =20 nfs_set_events(client); } - while (!task.complete) { - qemu_coroutine_yield(); - } + qemu_coroutine_yield(); =20 return task.ret; } @@ -723,8 +716,8 @@ nfs_get_allocated_file_size_cb(int ret, struct nfs_cont= ext *nfs, void *data, if (task->ret < 0) { error_report("NFS Error: %s", nfs_get_error(nfs)); } - replay_bh_schedule_oneshot_event(task->client->aio_context, - nfs_co_generic_bh_cb, task); + /* Safe to call, see nfs_co_generic_cb() */ + aio_co_wake(task->co); } =20 static int64_t coroutine_fn nfs_co_get_allocated_file_size(BlockDriverStat= e *bs) @@ -748,9 +741,7 @@ static int64_t coroutine_fn nfs_co_get_allocated_file_s= ize(BlockDriverState *bs) =20 nfs_set_events(client); } - while (!task.complete) { - qemu_coroutine_yield(); - } + qemu_coroutine_yield(); =20 return (task.ret < 0 ? task.ret : st.st_blocks * 512); } --=20 2.51.1