io_uring: kill REQ_F_LTIMEOUT_ACTIVE

Instead of handling double consecutive linked timeouts through tricky
flag combinations, just check the submit_state.link during timeout_prep
and fail that case in advance.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/04150760b0dc739522264b8abd309409f7421a06.1628981736.git.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 a23b608..abf8bb7 100644 (file)
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -705,7 +705,6 @@ enum {
        REQ_F_NEED_CLEANUP_BIT,
        REQ_F_POLLED_BIT,
        REQ_F_BUFFER_SELECTED_BIT,
-       REQ_F_LTIMEOUT_ACTIVE_BIT,
        REQ_F_COMPLETE_INLINE_BIT,
        REQ_F_REISSUE_BIT,
        REQ_F_DONT_REISSUE_BIT,
@@ -750,8 +749,6 @@ enum {
        REQ_F_POLLED            = BIT(REQ_F_POLLED_BIT),
        /* buffer already selected */
        REQ_F_BUFFER_SELECTED   = BIT(REQ_F_BUFFER_SELECTED_BIT),
-       /* linked timeout is active, i.e. prepared by link's head */
-       REQ_F_LTIMEOUT_ACTIVE   = BIT(REQ_F_LTIMEOUT_ACTIVE_BIT),
        /* completion is deferred through io_comp_state */
        REQ_F_COMPLETE_INLINE   = BIT(REQ_F_COMPLETE_INLINE_BIT),
        /* caller should reissue async */
@@ -1315,7 +1312,6 @@ static struct io_kiocb *__io_prep_linked_timeout(struct io_kiocb *req)
        __io_req_set_refcount(nxt, 2);
 
        nxt->timeout.head = req;
-       nxt->flags |= REQ_F_LTIMEOUT_ACTIVE;
        req->flags |= REQ_F_LINK_TIMEOUT;
        return nxt;
 }
@@ -1895,11 +1891,7 @@ static bool io_kill_linked_timeout(struct io_kiocb *req)
 {
        struct io_kiocb *link = req->link;
 
-       /*
-        * Can happen if a linked timeout fired and link had been like
-        * req -> link t-out -> link t-out [-> ...]
-        */
-       if (link && (link->flags & REQ_F_LTIMEOUT_ACTIVE)) {
+       if (link && link->opcode == IORING_OP_LINK_TIMEOUT) {
                struct io_timeout_data *io = link->async_data;
 
                io_remove_next_linked(req);
@@ -5700,6 +5692,15 @@ static int io_timeout_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe,
 
        data->mode = io_translate_timeout_mode(flags);
        hrtimer_init(&data->timer, CLOCK_MONOTONIC, data->mode);
+
+       if (is_timeout_link) {
+               struct io_submit_link *link = &req->ctx->submit_state.link;
+
+               if (!link->head)
+                       return -EINVAL;
+               if (link->last->opcode == IORING_OP_LINK_TIMEOUT)
+                       return -EINVAL;
+       }
        return 0;
 }