io_uring: add rsrc referencing for notifiers

In preparation to zerocopy sends with fixed buffers make notifiers to
reference the rsrc node to protect the used fixed buffers. We can't just
grab it for a send request as notifiers can likely outlive requests that
used it.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/3cd7a01d26837945b6982fa9cf15a63230f2ed4f.1657643355.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/io_uring/notif.c b/io_uring/notif.c
index aec74f8..0a2e98b 100644 (file)
--- a/io_uring/notif.c
+++ b/io_uring/notif.c
@@ -7,10 +7,12 @@
 
 #include "io_uring.h"
 #include "notif.h"
+#include "rsrc.h"
 
 static void __io_notif_complete_tw(struct callback_head *cb)
 {
        struct io_notif *notif = container_of(cb, struct io_notif, task_work);
+       struct io_rsrc_node *rsrc_node = notif->rsrc_node;
        struct io_ring_ctx *ctx = notif->ctx;
 
        if (likely(notif->task)) {
@@ -25,6 +27,7 @@ static void __io_notif_complete_tw(struct callback_head *cb)
        ctx->notif_locked_nr++;
        io_cq_unlock_post(ctx);
 
+       io_rsrc_put_node(rsrc_node, 1);
        percpu_ref_put(&ctx->refs);
 }
 
@@ -119,6 +122,8 @@ struct io_notif *io_alloc_notif(struct io_ring_ctx *ctx,
        /* master ref owned by io_notif_slot, will be dropped on flush */
        refcount_set(&notif->uarg.refcnt, 1);
        percpu_ref_get(&ctx->refs);
+       notif->rsrc_node = ctx->rsrc_node;
+       io_charge_rsrc_node(ctx);
        return notif;
 }
 

diff --git a/io_uring/notif.h b/io_uring/notif.h
index 23ca762..1dd48ef 100644 (file)
--- a/io_uring/notif.h
+++ b/io_uring/notif.h
@@ -10,6 +10,7 @@
 struct io_notif {
        struct ubuf_info        uarg;
        struct io_ring_ctx      *ctx;
+       struct io_rsrc_node     *rsrc_node;
 
        /* complete via tw if ->task is non-NULL, fallback to wq otherwise */
        struct task_struct      *task;

diff --git a/io_uring/rsrc.h b/io_uring/rsrc.h
index 87f5831..af342fd 100644 (file)
--- a/io_uring/rsrc.h
+++ b/io_uring/rsrc.h
@@ -135,6 +135,13 @@ static inline void io_req_put_rsrc_locked(struct io_kiocb *req,
        }
 }
 
+static inline void io_charge_rsrc_node(struct io_ring_ctx *ctx)
+{
+       ctx->rsrc_cached_refs--;
+       if (unlikely(ctx->rsrc_cached_refs < 0))
+               io_rsrc_refs_refill(ctx);
+}
+
 static inline void io_req_set_rsrc_node(struct io_kiocb *req,
                                        struct io_ring_ctx *ctx,
                                        unsigned int issue_flags)
@@ -144,9 +151,8 @@ static inline void io_req_set_rsrc_node(struct io_kiocb *req,
 
                if (!(issue_flags & IO_URING_F_UNLOCKED)) {
                        lockdep_assert_held(&ctx->uring_lock);
-                       ctx->rsrc_cached_refs--;
-                       if (unlikely(ctx->rsrc_cached_refs < 0))
-                               io_rsrc_refs_refill(ctx);
+
+                       io_charge_rsrc_node(ctx);
                } else {
                        percpu_ref_get(&req->rsrc_node->refs);
                }