io_uring: keep all sqe->flags in req->flags

It's a good idea to not read sqe->flags twice, as it's prone to security
bugs. Instead of passing it around, embeed them in req->flags. It's
already so except for IOSQE_IO_LINK.
1. rename former REQ_F_LINK -> REQ_F_LINK_HEAD
2. introduce and copy REQ_F_LINK, which mimics IO_IOSQE_LINK

And leave req_set_fail_links() using new REQ_F_LINK, because it's more
sensible.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/fs/io_uring.c b/fs/io_uring.c
index ff10bd4..b0e1bdf 100644 (file)
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -508,6 +508,7 @@ enum {
        REQ_F_FORCE_ASYNC_BIT   = IOSQE_ASYNC_BIT,
        REQ_F_BUFFER_SELECT_BIT = IOSQE_BUFFER_SELECT_BIT,
 
+       REQ_F_LINK_HEAD_BIT,
        REQ_F_LINK_NEXT_BIT,
        REQ_F_FAIL_LINK_BIT,
        REQ_F_INFLIGHT_BIT,
@@ -543,6 +544,8 @@ enum {
        /* IOSQE_BUFFER_SELECT */
        REQ_F_BUFFER_SELECT     = BIT(REQ_F_BUFFER_SELECT_BIT),
 
+       /* head of a link */
+       REQ_F_LINK_HEAD         = BIT(REQ_F_LINK_HEAD_BIT),
        /* already grabbed next link */
        REQ_F_LINK_NEXT         = BIT(REQ_F_LINK_NEXT_BIT),
        /* fail rest of links */
@@ -1437,7 +1440,7 @@ static bool io_link_cancel_timeout(struct io_kiocb *req)
        if (ret != -1) {
                io_cqring_fill_event(req, -ECANCELED);
                io_commit_cqring(ctx);
-               req->flags &= ~REQ_F_LINK;
+               req->flags &= ~REQ_F_LINK_HEAD;
                io_put_req(req);
                return true;
        }
@@ -1473,7 +1476,7 @@ static void io_req_link_next(struct io_kiocb *req, struct io_kiocb **nxtptr)
 
                list_del_init(&req->link_list);
                if (!list_empty(&nxt->link_list))
-                       nxt->flags |= REQ_F_LINK;
+                       nxt->flags |= REQ_F_LINK_HEAD;
                *nxtptr = nxt;
                break;
        }
@@ -1484,7 +1487,7 @@ static void io_req_link_next(struct io_kiocb *req, struct io_kiocb **nxtptr)
 }
 
 /*
- * Called if REQ_F_LINK is set, and we fail the head request
+ * Called if REQ_F_LINK_HEAD is set, and we fail the head request
  */
 static void io_fail_links(struct io_kiocb *req)
 {
@@ -1517,7 +1520,7 @@ static void io_fail_links(struct io_kiocb *req)
 
 static void io_req_find_next(struct io_kiocb *req, struct io_kiocb **nxt)
 {
-       if (likely(!(req->flags & REQ_F_LINK)))
+       if (likely(!(req->flags & REQ_F_LINK_HEAD)))
                return;
 
        /*
@@ -1669,7 +1672,7 @@ static inline unsigned int io_sqring_entries(struct io_ring_ctx *ctx)
 
 static inline bool io_req_multi_free(struct req_batch *rb, struct io_kiocb *req)
 {
-       if ((req->flags & REQ_F_LINK) || io_is_fallback_req(req))
+       if ((req->flags & REQ_F_LINK_HEAD) || io_is_fallback_req(req))
                return false;
 
        if (!(req->flags & REQ_F_FIXED_FILE) || req->io)
@@ -2562,7 +2565,7 @@ static int io_read(struct io_kiocb *req, bool force_nonblock)
 
        req->result = 0;
        io_size = ret;
-       if (req->flags & REQ_F_LINK)
+       if (req->flags & REQ_F_LINK_HEAD)
                req->result = io_size;
 
        /*
@@ -2653,7 +2656,7 @@ static int io_write(struct io_kiocb *req, bool force_nonblock)
 
        req->result = 0;
        io_size = ret;
-       if (req->flags & REQ_F_LINK)
+       if (req->flags & REQ_F_LINK_HEAD)
                req->result = io_size;
 
        /*
@@ -5476,7 +5479,7 @@ static struct io_kiocb *io_prep_linked_timeout(struct io_kiocb *req)
 {
        struct io_kiocb *nxt;
 
-       if (!(req->flags & REQ_F_LINK))
+       if (!(req->flags & REQ_F_LINK_HEAD))
                return NULL;
        /* for polled retry, if flag is set, we already went through here */
        if (req->flags & REQ_F_POLLED)
@@ -5636,7 +5639,7 @@ static int io_submit_sqe(struct io_kiocb *req, const struct io_uring_sqe *sqe,
        /* same numerical values with corresponding REQ_F_*, safe to copy */
        req->flags |= sqe_flags & (IOSQE_IO_DRAIN | IOSQE_IO_HARDLINK |
                                        IOSQE_ASYNC | IOSQE_FIXED_FILE |
-                                       IOSQE_BUFFER_SELECT);
+                                       IOSQE_BUFFER_SELECT | IOSQE_IO_LINK);
 
        fd = READ_ONCE(sqe->fd);
        ret = io_req_set_file(state, req, fd, sqe_flags);
@@ -5687,7 +5690,7 @@ static int io_submit_sqe(struct io_kiocb *req, const struct io_uring_sqe *sqe,
                        req->ctx->drain_next = 0;
                }
                if (sqe_flags & (IOSQE_IO_LINK|IOSQE_IO_HARDLINK)) {
-                       req->flags |= REQ_F_LINK;
+                       req->flags |= REQ_F_LINK_HEAD;
                        INIT_LIST_HEAD(&req->link_list);
 
                        if (io_alloc_async_ctx(req))