io_uring: file registration list and lock optimization

There's no point in using list_del_init() on entries that are going
away, and the associated lock is always used in process context so
let's not use the IRQ disabling+saving variant of the spinlock.

Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/fs/io_uring.c b/fs/io_uring.c
index f800b0b..c7622a5 100644 (file)
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -6264,16 +6264,15 @@ static int io_sqe_files_unregister(struct io_ring_ctx *ctx)
        struct fixed_file_data *data = ctx->file_data;
        struct fixed_file_ref_node *ref_node = NULL;
        unsigned nr_tables, i;
-       unsigned long flags;
 
        if (!data)
                return -ENXIO;
 
-       spin_lock_irqsave(&data->lock, flags);
+       spin_lock(&data->lock);
        if (!list_empty(&data->ref_list))
                ref_node = list_first_entry(&data->ref_list,
                                struct fixed_file_ref_node, node);
-       spin_unlock_irqrestore(&data->lock, flags);
+       spin_unlock(&data->lock);
        if (ref_node)
                percpu_ref_kill(&ref_node->refs);
 
@@ -6516,17 +6515,16 @@ static void __io_file_put_work(struct fixed_file_ref_node *ref_node)
        struct fixed_file_data *file_data = ref_node->file_data;
        struct io_ring_ctx *ctx = file_data->ctx;
        struct io_file_put *pfile, *tmp;
-       unsigned long flags;
 
        list_for_each_entry_safe(pfile, tmp, &ref_node->file_list, list) {
-               list_del_init(&pfile->list);
+               list_del(&pfile->list);
                io_ring_file_put(ctx, pfile->file);
                kfree(pfile);
        }
 
-       spin_lock_irqsave(&file_data->lock, flags);
-       list_del_init(&ref_node->node);
-       spin_unlock_irqrestore(&file_data->lock, flags);
+       spin_lock(&file_data->lock);
+       list_del(&ref_node->node);
+       spin_unlock(&file_data->lock);
 
        percpu_ref_exit(&ref_node->refs);
        kfree(ref_node);
@@ -6606,7 +6604,6 @@ static int io_sqe_files_register(struct io_ring_ctx *ctx, void __user *arg,
        int fd, ret = 0;
        unsigned i;
        struct fixed_file_ref_node *ref_node;
-       unsigned long flags;
 
        if (ctx->file_data)
                return -EBUSY;
@@ -6714,9 +6711,9 @@ static int io_sqe_files_register(struct io_ring_ctx *ctx, void __user *arg,
        }
 
        ctx->file_data->cur_refs = &ref_node->refs;
-       spin_lock_irqsave(&ctx->file_data->lock, flags);
+       spin_lock(&ctx->file_data->lock);
        list_add(&ref_node->node, &ctx->file_data->ref_list);
-       spin_unlock_irqrestore(&ctx->file_data->lock, flags);
+       spin_unlock(&ctx->file_data->lock);
        percpu_ref_get(&ctx->file_data->refs);
        return ret;
 }
@@ -6792,7 +6789,6 @@ static int __io_sqe_files_update(struct io_ring_ctx *ctx,
        __s32 __user *fds;
        int fd, i, err;
        __u32 done;
-       unsigned long flags;
        bool needs_switch = false;
 
        if (check_add_overflow(up->offset, nr_args, &done))
@@ -6857,10 +6853,10 @@ static int __io_sqe_files_update(struct io_ring_ctx *ctx,
 
        if (needs_switch) {
                percpu_ref_kill(data->cur_refs);
-               spin_lock_irqsave(&data->lock, flags);
+               spin_lock(&data->lock);
                list_add(&ref_node->node, &data->ref_list);
                data->cur_refs = &ref_node->refs;
-               spin_unlock_irqrestore(&data->lock, flags);
+               spin_unlock(&data->lock);
                percpu_ref_get(&ctx->file_data->refs);
        } else
                destroy_fixed_file_ref_node(ref_node);