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Subject[PATCH 1/1] io_uring: fix delayed mm check
Date
Fail fast if can't grab mm, so past that requests always have an mm
when required. This fixes not checking mm fault for
IORING_OP_{READ,WRITE}, as well allows to remove req->has_user
altogether.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
---

v2: remove ->has_user (Jens)

fs/io_uring.c | 20 ++++++++++----------
1 file changed, 10 insertions(+), 10 deletions(-)

diff --git a/fs/io_uring.c b/fs/io_uring.c
index ce3dbd2b1b5c..1914351ebd5e 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -516,6 +516,7 @@ enum {
REQ_F_TIMEOUT_NOSEQ = BIT(REQ_F_TIMEOUT_NOSEQ_BIT),
/* completion under lock */
REQ_F_COMP_LOCKED = BIT(REQ_F_COMP_LOCKED_BIT),
+
};

/*
@@ -548,7 +549,6 @@ struct io_kiocb {
* llist_node is only used for poll deferred completions
*/
struct llist_node llist_node;
- bool has_user;
bool in_async;
bool needs_fixed_file;
u8 opcode;
@@ -2051,9 +2051,6 @@ static ssize_t io_import_iovec(int rw, struct io_kiocb *req,
return iorw->size;
}

- if (!req->has_user)
- return -EFAULT;
-
#ifdef CONFIG_COMPAT
if (req->ctx->compat)
return compat_import_iovec(rw, buf, sqe_len, UIO_FASTIOV,
@@ -4418,7 +4415,6 @@ static void io_wq_submit_work(struct io_wq_work **workptr)
}

if (!ret) {
- req->has_user = (work->flags & IO_WQ_WORK_HAS_MM) != 0;
req->in_async = true;
do {
ret = io_issue_sqe(req, NULL, &nxt, false);
@@ -4922,6 +4918,7 @@ static int io_submit_sqes(struct io_ring_ctx *ctx, unsigned int nr,
for (i = 0; i < nr; i++) {
const struct io_uring_sqe *sqe;
struct io_kiocb *req;
+ int err;

req = io_get_req(ctx, statep);
if (unlikely(!req)) {
@@ -4938,20 +4935,23 @@ static int io_submit_sqes(struct io_ring_ctx *ctx, unsigned int nr,
submitted++;

if (unlikely(req->opcode >= IORING_OP_LAST)) {
- io_cqring_add_event(req, -EINVAL);
+ err = -EINVAL;
+fail_req:
+ io_cqring_add_event(req, err);
io_double_put_req(req);
break;
}

if (io_op_defs[req->opcode].needs_mm && !*mm) {
mm_fault = mm_fault || !mmget_not_zero(ctx->sqo_mm);
- if (!mm_fault) {
- use_mm(ctx->sqo_mm);
- *mm = ctx->sqo_mm;
+ if (unlikely(mm_fault)) {
+ err = -EFAULT;
+ goto fail_req;
}
+ use_mm(ctx->sqo_mm);
+ *mm = ctx->sqo_mm;
}

- req->has_user = *mm != NULL;
req->in_async = async;
req->needs_fixed_file = async;
trace_io_uring_submit_sqe(ctx, req->opcode, req->user_data,
--
2.24.0
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