[PATCH 02/11] io_uring/rsrc: keep cached refs per node

Pavel Begunkov
2023-03-30T14:54:39Z

We cache refs of the current node (i.e. ctx->rsrc_node) in
ctx->rsrc_cached_refs. We'll be moving away from atomics, so move the
cached refs in struct io_rsrc_node for now. It's a prep patch and
shouldn't change anything in practise.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
---
include/linux/io_uring_types.h | 1 -
io_uring/rsrc.c | 15 +++++++++------
io_uring/rsrc.h | 16 +++++++++-------
3 files changed, 18 insertions(+), 14 deletions(-)

diff --git a/include/linux/io_uring_types.h b/include/linux/io_uring_types.h
index 561fa421c453..a0a5b5964d3a 100644
--- a/include/linux/io_uring_types.h
+++ b/include/linux/io_uring_types.h
@@ -240,7 +240,6 @@ struct io_ring_ctx {
* uring_lock, and updated through io_uring_register(2)
*/
struct io_rsrc_node *rsrc_node;
- int rsrc_cached_refs;
atomic_t cancel_seq;
struct io_file_table file_table;
unsigned nr_user_files;
diff --git a/io_uring/rsrc.c b/io_uring/rsrc.c
index f2da9e251e3f..1e7c960737fd 100644
--- a/io_uring/rsrc.c
+++ b/io_uring/rsrc.c
@@ -36,9 +36,11 @@ static int io_sqe_buffer_register(struct io_ring_ctx *ctx, struct iovec *iov,
void io_rsrc_refs_drop(struct io_ring_ctx *ctx)
__must_hold(&ctx->uring_lock)
{
- if (ctx->rsrc_cached_refs) {
- io_rsrc_put_node(ctx->rsrc_node, ctx->rsrc_cached_refs);
- ctx->rsrc_cached_refs = 0;
+ struct io_rsrc_node *node = ctx->rsrc_node;
+
+ if (node && node->cached_refs) {
+ io_rsrc_put_node(node, node->cached_refs);
+ node->cached_refs = 0;
}
}

@@ -151,11 +153,11 @@ static void io_buffer_unmap(struct io_ring_ctx *ctx, struct io_mapped_ubuf **slo
*slot = NULL;
}

-void io_rsrc_refs_refill(struct io_ring_ctx *ctx)
+void io_rsrc_refs_refill(struct io_ring_ctx *ctx, struct io_rsrc_node *node)
__must_hold(&ctx->uring_lock)
{
- ctx->rsrc_cached_refs += IO_RSRC_REF_BATCH;
- refcount_add(IO_RSRC_REF_BATCH, &ctx->rsrc_node->refs);
+ node->cached_refs += IO_RSRC_REF_BATCH;
+ refcount_add(IO_RSRC_REF_BATCH, &node->refs);
}

static void __io_rsrc_put_work(struct io_rsrc_node *ref_node)
@@ -300,6 +302,7 @@ void io_rsrc_node_switch(struct io_ring_ctx *ctx,
if (!ctx->rsrc_node) {
ctx->rsrc_node = ctx->rsrc_backup_node;
ctx->rsrc_backup_node = NULL;
+ ctx->rsrc_node->cached_refs = 0;
}
}

diff --git a/io_uring/rsrc.h b/io_uring/rsrc.h
index 1467b31843bc..950535e2b9f4 100644
--- a/io_uring/rsrc.h
+++ b/io_uring/rsrc.h
@@ -43,6 +43,7 @@ struct io_rsrc_node {
struct io_rsrc_data *rsrc_data;
struct llist_node llist;
bool done;
+ int cached_refs;
};

struct io_mapped_ubuf {
@@ -56,7 +57,7 @@ struct io_mapped_ubuf {
void io_rsrc_put_tw(struct callback_head *cb);
void io_rsrc_node_ref_zero(struct io_rsrc_node *node);
void io_rsrc_put_work(struct work_struct *work);
-void io_rsrc_refs_refill(struct io_ring_ctx *ctx);
+void io_rsrc_refs_refill(struct io_ring_ctx *ctx, struct io_rsrc_node *node);
void io_wait_rsrc_data(struct io_rsrc_data *data);
void io_rsrc_node_destroy(struct io_rsrc_node *ref_node);
void io_rsrc_refs_drop(struct io_ring_ctx *ctx);
@@ -128,17 +129,18 @@ static inline void io_req_put_rsrc_locked(struct io_kiocb *req,

if (node) {
if (node == ctx->rsrc_node)
- ctx->rsrc_cached_refs++;
+ node->cached_refs++;
else
io_rsrc_put_node(node, 1);
}
}

-static inline void io_charge_rsrc_node(struct io_ring_ctx *ctx)
+static inline void io_charge_rsrc_node(struct io_ring_ctx *ctx,
+ struct io_rsrc_node *node)
{
- ctx->rsrc_cached_refs--;
- if (unlikely(ctx->rsrc_cached_refs < 0))
- io_rsrc_refs_refill(ctx);
+ node->cached_refs--;
+ if (unlikely(node->cached_refs < 0))
+ io_rsrc_refs_refill(ctx, node);
}

static inline void io_req_set_rsrc_node(struct io_kiocb *req,
@@ -151,7 +153,7 @@ static inline void io_req_set_rsrc_node(struct io_kiocb *req,
lockdep_assert_held(&ctx->uring_lock);

req->rsrc_node = ctx->rsrc_node;
- io_charge_rsrc_node(ctx);
+ io_charge_rsrc_node(ctx, ctx->rsrc_node);
io_ring_submit_unlock(ctx, issue_flags);
}
}
--
2.39.1