io_uring: enable task/files specific overflow flushing

This allows us to selectively flush out pending overflows, depending on
the task and/or files_struct being passed in.

No intended functional changes in this patch.

Reviewed-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 5ddb8b2..046d062 100644 (file)
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -1344,12 +1344,24 @@ static void io_cqring_mark_overflow(struct io_ring_ctx *ctx)
        }
 }
 
+static inline bool io_match_files(struct io_kiocb *req,
+                                      struct files_struct *files)
+{
+       if (!files)
+               return true;
+       if (req->flags & REQ_F_WORK_INITIALIZED)
+               return req->work.files == files;
+       return false;
+}
+
 /* Returns true if there are no backlogged entries after the flush */
-static bool io_cqring_overflow_flush(struct io_ring_ctx *ctx, bool force)
+static bool io_cqring_overflow_flush(struct io_ring_ctx *ctx, bool force,
+                                    struct task_struct *tsk,
+                                    struct files_struct *files)
 {
        struct io_rings *rings = ctx->rings;
+       struct io_kiocb *req, *tmp;
        struct io_uring_cqe *cqe;
-       struct io_kiocb *req;
        unsigned long flags;
        LIST_HEAD(list);
 
@@ -1368,13 +1380,16 @@ static bool io_cqring_overflow_flush(struct io_ring_ctx *ctx, bool force)
                ctx->cq_overflow_flushed = 1;
 
        cqe = NULL;
-       while (!list_empty(&ctx->cq_overflow_list)) {
+       list_for_each_entry_safe(req, tmp, &ctx->cq_overflow_list, compl.list) {
+               if (tsk && req->task != tsk)
+                       continue;
+               if (!io_match_files(req, files))
+                       continue;
+
                cqe = io_get_cqring(ctx);
                if (!cqe && !force)
                        break;
 
-               req = list_first_entry(&ctx->cq_overflow_list, struct io_kiocb,
-                                               compl.list);
                list_move(&req->compl.list, &list);
                if (cqe) {
                        WRITE_ONCE(cqe->user_data, req->user_data);
@@ -1988,7 +2003,7 @@ static unsigned io_cqring_events(struct io_ring_ctx *ctx, bool noflush)
                if (noflush && !list_empty(&ctx->cq_overflow_list))
                        return -1U;
 
-               io_cqring_overflow_flush(ctx, false);
+               io_cqring_overflow_flush(ctx, false, NULL, NULL);
        }
 
        /* See comment at the top of this file */
@@ -6489,7 +6504,7 @@ static int io_submit_sqes(struct io_ring_ctx *ctx, unsigned int nr,
        /* if we have a backlog and couldn't flush it all, return BUSY */
        if (test_bit(0, &ctx->sq_check_overflow)) {
                if (!list_empty(&ctx->cq_overflow_list) &&
-                   !io_cqring_overflow_flush(ctx, false))
+                   !io_cqring_overflow_flush(ctx, false, NULL, NULL))
                        return -EBUSY;
        }
 
@@ -7993,7 +8008,7 @@ static void io_ring_exit_work(struct work_struct *work)
         */
        do {
                if (ctx->rings)
-                       io_cqring_overflow_flush(ctx, true);
+                       io_cqring_overflow_flush(ctx, true, NULL, NULL);
                io_iopoll_try_reap_events(ctx);
        } while (!wait_for_completion_timeout(&ctx->ref_comp, HZ/20));
        io_ring_ctx_free(ctx);
@@ -8013,7 +8028,7 @@ static void io_ring_ctx_wait_and_kill(struct io_ring_ctx *ctx)
 
        /* if we failed setting up the ctx, we might not have any rings */
        if (ctx->rings)
-               io_cqring_overflow_flush(ctx, true);
+               io_cqring_overflow_flush(ctx, true, NULL, NULL);
        io_iopoll_try_reap_events(ctx);
        idr_for_each(&ctx->personality_idr, io_remove_personalities, ctx);
 
@@ -8069,12 +8084,6 @@ static bool io_match_link(struct io_kiocb *preq, struct io_kiocb *req)
        return false;
 }
 
-static inline bool io_match_files(struct io_kiocb *req,
-                                      struct files_struct *files)
-{
-       return (req->flags & REQ_F_WORK_INITIALIZED) && req->work.files == files;
-}
-
 static bool io_match_link_files(struct io_kiocb *req,
                                struct files_struct *files)
 {
@@ -8365,7 +8374,7 @@ SYSCALL_DEFINE6(io_uring_enter, unsigned int, fd, u32, to_submit,
        ret = 0;
        if (ctx->flags & IORING_SETUP_SQPOLL) {
                if (!list_empty_careful(&ctx->cq_overflow_list))
-                       io_cqring_overflow_flush(ctx, false);
+                       io_cqring_overflow_flush(ctx, false, NULL, NULL);
                if (flags & IORING_ENTER_SQ_WAKEUP)
                        wake_up(&ctx->sqo_wait);
                submitted = to_submit;