[PATCH 19/19] io_uring: add io_uring_event cache hit information
From: Jens Axboe <axboe@kernel.dk>
Date: 2019-02-08 17:38:39
Also in:
linux-block
Subsystem:
filesystems (vfs and infrastructure), io_uring, the rest · Maintainers:
Alexander Viro, Christian Brauner, Jens Axboe, Linus Torvalds
Add hint on whether a read was served out of the page cache, or if it hit media. This is useful for buffered async IO, O_DIRECT reads would never have this set (for obvious reasons). If the read hit page cache, cqe->flags will have IOCQE_FLAG_CACHEHIT set. Signed-off-by: Jens Axboe <axboe@kernel.dk> --- fs/io_uring.c | 7 ++++++- include/uapi/linux/io_uring.h | 5 +++++ 2 files changed, 11 insertions(+), 1 deletion(-)
diff --git a/fs/io_uring.c b/fs/io_uring.c
index 175dac00eb47..48e864de5dca 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c@@ -583,11 +583,16 @@ static void io_fput(struct io_kiocb *req) static void io_complete_rw(struct kiocb *kiocb, long res, long res2) { struct io_kiocb *req = container_of(kiocb, struct io_kiocb, rw); + unsigned ev_flags = 0; kiocb_end_write(kiocb); io_fput(req); - io_cqring_add_event(req->ctx, req->user_data, res, 0); + + if (res > 0 && (req->flags & REQ_F_FORCE_NONBLOCK)) + ev_flags = IOCQE_FLAG_CACHEHIT; + + io_cqring_add_event(req->ctx, req->user_data, res, ev_flags); io_free_req(req); }
diff --git a/include/uapi/linux/io_uring.h b/include/uapi/linux/io_uring.h
index e23408692118..24906e99fdc7 100644
--- a/include/uapi/linux/io_uring.h
+++ b/include/uapi/linux/io_uring.h@@ -69,6 +69,11 @@ struct io_uring_cqe { __u32 flags; }; +/* + * io_uring_event->flags + */ +#define IOCQE_FLAG_CACHEHIT (1U << 0) /* IO did not hit media */ + /* * Magic offsets for the application to mmap the data it needs */
--
2.17.1
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