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From: Jens Axboe <axboe@kernel.dk>
To: linux-fsdevel@vger.kernel.org, linux-aio@kvack.org,
	linux-block@vger.kernel.org, linux-arch@vger.kernel.org
Cc: hch@lst.de, jmoyer@redhat.com, avi@scylladb.com,
	Jens Axboe <axboe@kernel.dk>
Subject: [PATCH 15/15] io_uring: add io_uring_event cache hit information
Date: Wed,  9 Jan 2019 19:44:04 -0700
Message-ID: <20190110024404.25372-16-axboe@kernel.dk> (raw)
In-Reply-To: <20190110024404.25372-1-axboe@kernel.dk>

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 6c62329b00ec..f2a603c447ba 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -511,11 +511,16 @@ static void io_fill_cq_error(struct io_ring_ctx *ctx, struct sqe_submit *s,
 static void io_complete_scqring_rw(struct kiocb *kiocb, long res, long res2)
 {
 	struct io_kiocb *iocb = container_of(kiocb, struct io_kiocb, rw);
+	unsigned ev_flags = 0;
 
 	kiocb_end_write(kiocb);
 
 	fput(kiocb->ki_filp);
-	io_cqring_fill_event(iocb->ki_ctx, iocb->ki_index, res, 0);
+
+	if (res > 0 && test_bit(KIOCB_F_FORCE_NONBLOCK, &iocb->ki_flags))
+		ev_flags = IOCQE_FLAG_CACHEHIT;
+
+	io_cqring_fill_event(iocb->ki_ctx, iocb->ki_index, res, ev_flags);
 	io_free_kiocb(iocb);
 }
 
diff --git a/include/uapi/linux/io_uring.h b/include/uapi/linux/io_uring.h
index 9321eb97479d..20e4c22e040d 100644
--- a/include/uapi/linux/io_uring.h
+++ b/include/uapi/linux/io_uring.h
@@ -55,6 +55,11 @@ struct io_uring_cqe {
 	__u32	flags;
 };
 
+/*
+ * io_uring_event->flags
+ */
+#define IOCQE_FLAG_CACHEHIT	(1 << 0)	/* IO did not hit media */
+
 /*
  * Magic offsets for the application to mmap the data it needs
  */
-- 
2.17.1


  parent reply index

Thread overview: 28+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-01-10  2:43 [PATCHSET v2] io_uring IO interface Jens Axboe
2019-01-10  2:43 ` [PATCH 01/15] fs: add an iopoll method to struct file_operations Jens Axboe
2019-01-10  2:43 ` [PATCH 02/15] block: wire up block device iopoll method Jens Axboe
2019-01-10  2:43 ` [PATCH 03/15] block: add bio_set_polled() helper Jens Axboe
2019-01-10  2:43 ` [PATCH 04/15] iomap: wire up the iopoll method Jens Axboe
2019-01-10  2:43 ` [PATCH 05/15] Add io_uring IO interface Jens Axboe
2019-01-11 18:19   ` Martin K. Petersen
2019-01-11 18:34     ` Jens Axboe
2019-01-13 16:22       ` Jens Axboe
2019-01-15 17:31         ` Martin K. Petersen
2019-01-10  2:43 ` [PATCH 06/15] io_uring: support for IO polling Jens Axboe
2019-01-10  2:43 ` [PATCH 07/15] io_uring: add submission side request cache Jens Axboe
2019-01-10  2:43 ` [PATCH 08/15] fs: add fget_many() and fput_many() Jens Axboe
2019-01-10  2:43 ` [PATCH 09/15] io_uring: use fget/fput_many() for file references Jens Axboe
2019-01-10  2:43 ` [PATCH 10/15] io_uring: batch io_kiocb allocation Jens Axboe
2019-01-10  2:44 ` [PATCH 11/15] block: implement bio helper to add iter bvec pages to bio Jens Axboe
2019-01-10  2:44 ` [PATCH 12/15] io_uring: add support for pre-mapped user IO buffers Jens Axboe
2019-01-10  2:44 ` [PATCH 13/15] io_uring: support kernel side submission Jens Axboe
2019-01-10  2:44 ` [PATCH 14/15] io_uring: add submission polling Jens Axboe
2019-01-10  2:44 ` Jens Axboe [this message]
2019-01-10 23:12   ` [PATCH 15/15] io_uring: add io_uring_event cache hit information Jeff Moyer
2019-01-10 23:47     ` Jens Axboe
2019-01-11  9:46 ` [PATCHSET v2] io_uring IO interface Roman Penyaev
2019-01-11 16:11   ` Ilya Dryomov
2019-01-11 16:21     ` Christoph Hellwig
2019-01-11 16:39     ` Roman Penyaev
2019-01-11 18:05   ` Jens Axboe
2019-01-16 17:49 [PATCHSET v5] " Jens Axboe
2019-01-16 17:50 ` [PATCH 15/15] io_uring: add io_uring_event cache hit information Jens Axboe

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