io_uring: better locality for rsrc fields

ring has two types of resource-related fields: used for request
submission, and field needed for update/registration. Reshuffle them
into these two groups for better locality and readability. The second
group is not in the hot path, so it's natural to place them somewhere in
the end. Also update an outdated comment.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/05b34795bb4440f4ec4510f08abd5a31830f8ca0.1621201931.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 6e19fe04a5d16f635c25cdfd1be1e197edb15016..f628af3a33685fdc63e00a9a19069dc9ef355507 100644 (file)
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -391,21 +391,17 @@ struct io_ring_ctx {
        struct list_head        sqd_list;
 
        /*
-        * If used, fixed file set. Writers must ensure that ->refs is dead,
-        * readers must ensure that ->refs is alive as long as the file* is
-        * used. Only updated through io_uring_register(2).
+        * Fixed resources fast path, should be accessed only under uring_lock,
+        * and updated through io_uring_register(2)
         */
-       struct io_rsrc_data     *file_data;
+       struct io_rsrc_node     *rsrc_node;
+
        struct io_file_table    file_table;
        unsigned                nr_user_files;
-
-       /* if used, fixed mapped user buffers */
-       struct io_rsrc_data     *buf_data;
        unsigned                nr_user_bufs;
        struct io_mapped_ubuf   **user_bufs;
 
        struct xarray           io_buffers;
-
        struct xarray           personalities;
        u32                     pers_next;
 
@@ -437,16 +433,21 @@ struct io_ring_ctx {
                bool                    poll_multi_file;
        } ____cacheline_aligned_in_smp;
 
-       struct delayed_work             rsrc_put_work;
-       struct llist_head               rsrc_put_llist;
-       struct list_head                rsrc_ref_list;
-       spinlock_t                      rsrc_ref_lock;
-       struct io_rsrc_node             *rsrc_node;
-       struct io_rsrc_node             *rsrc_backup_node;
-       struct io_mapped_ubuf           *dummy_ubuf;
-
        struct io_restriction           restrictions;
 
+       /* slow path rsrc auxilary data, used by update/register */
+       struct {
+               struct io_rsrc_node             *rsrc_backup_node;
+               struct io_mapped_ubuf           *dummy_ubuf;
+               struct io_rsrc_data             *file_data;
+               struct io_rsrc_data             *buf_data;
+
+               struct delayed_work             rsrc_put_work;
+               struct llist_head               rsrc_put_llist;
+               struct list_head                rsrc_ref_list;
+               spinlock_t                      rsrc_ref_lock;
+       };
+
        /* Keep this last, we don't need it for the fast path */
        struct {
                #if defined(CONFIG_UNIX)