[PATCH 3/8] aio: store event at final iocb_put()

From: Al Viro <viro@ZenIV.linux.org.uk>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Eric Dumazet <eric.dumazet@gmail.com>,
	David Miller <davem@davemloft.net>,
	Jason Baron <jbaron@akamai.com>,
	kgraul@linux.ibm.com, ktkhai@virtuozzo.com,
	kyeongdon.kim@lge.com,
	Linux List Kernel Mailing <linux-kernel@vger.kernel.org>,
	Netdev <netdev@vger.kernel.org>,
	pabeni@redhat.com, syzkaller-bugs@googlegroups.com,
	xiyou.wangcong@gmail.com, Christoph Hellwig <hch@lst.de>,
	zhengbin <zhengbin13@huawei.com>,
	bcrl@kvack.org, linux-fsdevel@vger.kernel.org,
	linux-aio@kvack.org, houtao1@huawei.com, yi.zhang@huawei.com
Subject: [PATCH 3/8] aio: store event at final iocb_put()
Date: Sun, 10 Mar 2019 07:08:17 +0000	[thread overview]
Message-ID: <20190310070822.11564-3-viro@ZenIV.linux.org.uk> (raw)
In-Reply-To: <20190310070822.11564-1-viro@ZenIV.linux.org.uk>

From: Al Viro <viro@zeniv.linux.org.uk>

Instead of having aio_complete() set ->ki_res.{res,res2}, do that
explicitly in its callers, drop the reference (as aio_complete()
used to do) and delay the rest until the final iocb_put().

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---
 fs/aio.c | 45 ++++++++++++++++++++-------------------------
 1 file changed, 20 insertions(+), 25 deletions(-)

diff --git a/fs/aio.c b/fs/aio.c
index 2249a7a1d6b3..b9c4c1894020 100644
--- a/fs/aio.c
+++ b/fs/aio.c
@@ -1077,24 +1077,10 @@ static inline void iocb_destroy(struct aio_kiocb *iocb)
 	kmem_cache_free(kiocb_cachep, iocb);
 }
 
-static inline void iocb_put(struct aio_kiocb *iocb)
-{
-	if (refcount_dec_and_test(&iocb->ki_refcnt))
-		iocb_destroy(iocb);
-}
-
-static void aio_fill_event(struct io_event *ev, struct aio_kiocb *iocb,
-			   long res, long res2)
-{
-	iocb->ki_res.res = res;
-	iocb->ki_res.res2 = res2;
-	*ev = iocb->ki_res;
-}
-
 /* aio_complete
  *	Called when the io request on the given iocb is complete.
  */
-static void aio_complete(struct aio_kiocb *iocb, long res, long res2)
+static void aio_complete(struct aio_kiocb *iocb)
 {
 	struct kioctx	*ctx = iocb->ki_ctx;
 	struct aio_ring	*ring;
@@ -1118,14 +1104,14 @@ static void aio_complete(struct aio_kiocb *iocb, long res, long res2)
 	ev_page = kmap_atomic(ctx->ring_pages[pos / AIO_EVENTS_PER_PAGE]);
 	event = ev_page + pos % AIO_EVENTS_PER_PAGE;
 
-	aio_fill_event(event, iocb, res, res2);
+	*event = iocb->ki_res;
 
 	kunmap_atomic(ev_page);
 	flush_dcache_page(ctx->ring_pages[pos / AIO_EVENTS_PER_PAGE]);
 
-	pr_debug("%p[%u]: %p: %p %Lx %lx %lx\n",
+	pr_debug("%p[%u]: %p: %p %Lx %Lx %Lx\n",
 		 ctx, tail, iocb, (void __user *)iocb->ki_res.obj, iocb->ki_res.data,
-		 res, res2);
+		 iocb->ki_res.res, iocb->ki_res.res2);
 
 	/* after flagging the request as done, we
 	 * must never even look at it again
@@ -1167,7 +1153,14 @@ static void aio_complete(struct aio_kiocb *iocb, long res, long res2)
 
 	if (waitqueue_active(&ctx->wait))
 		wake_up(&ctx->wait);
-	iocb_put(iocb);
+}
+
+static inline void iocb_put(struct aio_kiocb *iocb)
+{
+	if (refcount_dec_and_test(&iocb->ki_refcnt)) {
+		aio_complete(iocb);
+		iocb_destroy(iocb);
+	}
 }
 
 /* aio_read_events_ring
@@ -1441,7 +1434,9 @@ static void aio_complete_rw(struct kiocb *kiocb, long res, long res2)
 		file_end_write(kiocb->ki_filp);
 	}
 
-	aio_complete(iocb, res, res2);
+	iocb->ki_res.res = res;
+	iocb->ki_res.res2 = res2;
+	iocb_put(iocb);
 }
 
 static int aio_prep_rw(struct kiocb *req, const struct iocb *iocb)
@@ -1589,11 +1584,10 @@ static ssize_t aio_write(struct kiocb *req, const struct iocb *iocb,
 
 static void aio_fsync_work(struct work_struct *work)
 {
-	struct fsync_iocb *req = container_of(work, struct fsync_iocb, work);
-	int ret;
+	struct aio_kiocb *iocb = container_of(work, struct aio_kiocb, fsync.work);
 
-	ret = vfs_fsync(req->file, req->datasync);
-	aio_complete(container_of(req, struct aio_kiocb, fsync), ret, 0);
+	iocb->ki_res.res = vfs_fsync(iocb->fsync.file, iocb->fsync.datasync);
+	iocb_put(iocb);
 }
 
 static int aio_fsync(struct fsync_iocb *req, const struct iocb *iocb,
@@ -1614,7 +1608,8 @@ static int aio_fsync(struct fsync_iocb *req, const struct iocb *iocb,
 
 static inline void aio_poll_complete(struct aio_kiocb *iocb, __poll_t mask)
 {
-	aio_complete(iocb, mangle_poll(mask), 0);
+	iocb->ki_res.res = mangle_poll(mask);
+	iocb_put(iocb);
 }
 
 static void aio_poll_complete_work(struct work_struct *work)
-- 
2.11.0

