linux-kernel - [PATCH 1/2] io_uring: handle mm

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Message-Id: <e208444f3c22d2ee118e88b8e0d591ee6c80a1e3.1572189860.git.asml.silence@gmail.com>
Date:   Sun, 27 Oct 2019 18:35:04 +0300
From:   Pavel Begunkov <asml.silence@...il.com>
To:     Jens Axboe <axboe@...nel.dk>, linux-block@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH 1/2] io_uring: handle mm_fault outside of submission

Preparation for the following patch.
Let callers of io_submit_sqes() handle an mm_fault case.

Signed-off-by: Pavel Begunkov <asml.silence@...il.com>
---
 fs/io_uring.c | 44 ++++++++++++++++++++++++++------------------
 1 file changed, 26 insertions(+), 18 deletions(-)

diff --git a/fs/io_uring.c b/fs/io_uring.c
index 76cc8add9e77..f65727f2ba95 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -2640,7 +2640,7 @@ static bool io_get_sqring(struct io_ring_ctx *ctx, struct sqe_submit *s)
 }
 
 static int io_submit_sqes(struct io_ring_ctx *ctx, unsigned int nr,
-			  bool has_user, bool mm_fault)
+			  bool has_user)
 {
 	struct io_submit_state state, *statep = NULL;
 	struct io_kiocb *link = NULL;
@@ -2682,17 +2682,12 @@ static int io_submit_sqes(struct io_ring_ctx *ctx, unsigned int nr,
 		}
 
 out:
-		if (unlikely(mm_fault)) {
-			io_cqring_add_event(ctx, s.sqe->user_data,
-						-EFAULT);
-		} else {
-			s.has_user = has_user;
-			s.in_async = true;
-			s.needs_fixed_file = true;
-			trace_io_uring_submit_sqe(ctx, true, true);
-			io_submit_sqe(ctx, &s, statep, &link);
-			submitted++;
-		}
+		s.has_user = has_user;
+		s.in_async = true;
+		s.needs_fixed_file = true;
+		trace_io_uring_submit_sqe(ctx, true, true);
+		io_submit_sqe(ctx, &s, statep, &link);
+		submitted++;
 	}
 
 	if (link)
@@ -2703,6 +2698,16 @@ static int io_submit_sqes(struct io_ring_ctx *ctx, unsigned int nr,
 	return submitted;
 }
 
+static void io_fail_all_sqes(struct io_ring_ctx *ctx)
+{
+	struct sqe_submit s;
+
+	while (io_get_sqring(ctx, &s))
+		io_cqring_add_event(ctx, s.sqe->user_data, -EFAULT);
+
+	io_commit_sqring(ctx);
+}
+
 static int io_sq_thread(void *data)
 {
 	struct io_ring_ctx *ctx = data;
@@ -2813,12 +2818,15 @@ static int io_sq_thread(void *data)
 			}
 		}
 
-		to_submit = min(to_submit, ctx->sq_entries);
-		inflight += io_submit_sqes(ctx, to_submit, cur_mm != NULL,
-					   mm_fault);
-
-		/* Commit SQ ring head once we've consumed all SQEs */
-		io_commit_sqring(ctx);
+		if (unlikely(mm_fault)) {
+			io_fail_all_sqes(ctx);
+		} else {
+			to_submit = min(to_submit, ctx->sq_entries);
+			inflight += io_submit_sqes(ctx, to_submit,
+						   cur_mm != NULL);
+			/* Commit SQ ring head once we've consumed all SQEs */
+			io_commit_sqring(ctx);
+		}
 	}
 
 	set_fs(old_fs);
-- 
2.23.0