io_uring: fix wrong sequence setting logic

[ Upstream commit 8776f3fa15a5cd213c4dfab7ddaf557983374ea6 ]

Sqo_thread will get sqring in batches, which will cause
ctx->cached_sq_head to be added in batches. if one of these
sqes is set with the DRAIN flag, then he will never get a
chance to process, and finally sqo_thread will not exit.

Fixes: de0617e4671 ("io_uring: add support for marking commands as draining")
Signed-off-by: Jackie Liu <liuyun01@kylinos.cn>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/fs/io_uring.c b/fs/io_uring.c
index 03cd8f5bba850fab570b9c65a3235e05a57c64f7..701936f2bde391a8da9044175827ac29732a93ee 100644 (file)
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -288,6 +288,7 @@ struct io_ring_ctx {
 struct sqe_submit {
        const struct io_uring_sqe       *sqe;
        unsigned short                  index;
+       u32                             sequence;
        bool                            has_user;
        bool                            needs_lock;
        bool                            needs_fixed_file;
@@ -1894,7 +1895,7 @@ static int io_req_set_file(struct io_ring_ctx *ctx, const struct sqe_submit *s,
 
        if (flags & IOSQE_IO_DRAIN) {
                req->flags |= REQ_F_IO_DRAIN;
-               req->sequence = ctx->cached_sq_head - 1;
+               req->sequence = s->sequence;
        }
 
        if (!io_op_needs_file(s->sqe))
@@ -2050,6 +2051,7 @@ static bool io_get_sqring(struct io_ring_ctx *ctx, struct sqe_submit *s)
        if (head < ctx->sq_entries) {
                s->index = head;
                s->sqe = &ctx->sq_sqes[head];
+               s->sequence = ctx->cached_sq_head;
                ctx->cached_sq_head++;
                return true;
        }