io_uring: split file table from rsrc nodes

We don't need to store file tables in rsrc nodes, for now it's easier to
handle tables not generically, so move file tables into the context. A
nice side effect is having one less pointer dereference for request with
fixed file initialisation.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/de9fc4cd3545f24c26c03be4556f58ba3d18b9c3.1618101759.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

fs/io_uring.c

@@ -220,8 +220,9 @@ struct io_rsrc_put {
 	};
 };
 
-struct fixed_rsrc_table {
-	struct io_fixed_file *files;
+struct io_file_table {
+	/* two level table */
+	struct io_fixed_file **files;
 };
 
 struct io_rsrc_node {
@@ -236,7 +237,6 @@ struct io_rsrc_node {
 typedef void (rsrc_put_fn)(struct io_ring_ctx *ctx, struct io_rsrc_put *prsrc);
 
 struct io_rsrc_data {
-	struct fixed_rsrc_table		*table;
 	struct io_ring_ctx		*ctx;
 
 	rsrc_put_fn			*do_put;
@@ -398,6 +398,7 @@ struct io_ring_ctx {
 	 * used. Only updated through io_uring_register(2).
 	 */
 	struct io_rsrc_data	*file_data;
+	struct io_file_table	file_table;
 	unsigned		nr_user_files;
 
 	/* if used, fixed mapped user buffers */
@@ -6265,19 +6266,19 @@ static void io_wq_submit_work(struct io_wq_work *work)
 #endif
 #define FFS_MASK		~(FFS_ASYNC_READ|FFS_ASYNC_WRITE|FFS_ISREG)
 
-static inline struct io_fixed_file *io_fixed_file_slot(struct io_rsrc_data *file_data,
+static inline struct io_fixed_file *io_fixed_file_slot(struct io_file_table *table,
 						      unsigned i)
 {
-	struct fixed_rsrc_table *table;
+	struct io_fixed_file *table_l2;
 
-	table = &file_data->table[i >> IORING_FILE_TABLE_SHIFT];
-	return &table->files[i & IORING_FILE_TABLE_MASK];
+	table_l2 = table->files[i >> IORING_FILE_TABLE_SHIFT];
+	return &table_l2[i & IORING_FILE_TABLE_MASK];
 }
 
 static inline struct file *io_file_from_index(struct io_ring_ctx *ctx,
 					      int index)
 {
-	struct io_fixed_file *slot = io_fixed_file_slot(ctx->file_data, index);
+	struct io_fixed_file *slot = io_fixed_file_slot(&ctx->file_table, index);
 
 	return (struct file *) (slot->file_ptr & FFS_MASK);
 }
@@ -6307,7 +6308,7 @@ static struct file *io_file_get(struct io_submit_state *state,
 		if (unlikely((unsigned int)fd >= ctx->nr_user_files))
 			return NULL;
 		fd = array_index_nospec(fd, ctx->nr_user_files);
-		file_ptr = io_fixed_file_slot(ctx->file_data, fd)->file_ptr;
+		file_ptr = io_fixed_file_slot(&ctx->file_table, fd)->file_ptr;
 		file = (struct file *) (file_ptr & FFS_MASK);
 		file_ptr &= ~FFS_MASK;
 		/* mask in overlapping REQ_F and FFS bits */
@@ -7044,14 +7045,14 @@ static int io_cqring_wait(struct io_ring_ctx *ctx, int min_events,
 	return READ_ONCE(rings->cq.head) == READ_ONCE(rings->cq.tail) ? ret : 0;
 }
 
-static void io_free_file_tables(struct io_rsrc_data *data, unsigned nr_files)
+static void io_free_file_tables(struct io_file_table *table, unsigned nr_files)
 {
 	unsigned i, nr_tables = DIV_ROUND_UP(nr_files, IORING_MAX_FILES_TABLE);
 
 	for (i = 0; i < nr_tables; i++)
-		kfree(data->table[i].files);
-	kfree(data->table);
-	data->table = NULL;
+		kfree(table->files[i]);
+	kfree(table->files);
+	table->files = NULL;
 }
 
 static void __io_sqe_files_unregister(struct io_ring_ctx *ctx)
@@ -7191,7 +7192,7 @@ static int io_sqe_files_unregister(struct io_ring_ctx *ctx)
 		return ret;
 
 	__io_sqe_files_unregister(ctx);
-	io_free_file_tables(data, ctx->nr_user_files);
+	io_free_file_tables(&ctx->file_table, ctx->nr_user_files);
 	kfree(data);
 	ctx->file_data = NULL;
 	ctx->nr_user_files = 0;
@@ -7421,23 +7422,20 @@ static int io_sqe_files_scm(struct io_ring_ctx *ctx)
 }
 #endif
 
-static bool io_alloc_file_tables(struct io_rsrc_data *file_data,
-				 unsigned nr_files)
+static bool io_alloc_file_tables(struct io_file_table *table, unsigned nr_files)
 {
 	unsigned i, nr_tables = DIV_ROUND_UP(nr_files, IORING_MAX_FILES_TABLE);
 
-	file_data->table = kcalloc(nr_tables, sizeof(*file_data->table),
-				   GFP_KERNEL);
-	if (!file_data->table)
+	table->files = kcalloc(nr_tables, sizeof(*table->files), GFP_KERNEL);
+	if (!table->files)
 		return false;
 
 	for (i = 0; i < nr_tables; i++) {
-		struct fixed_rsrc_table *table = &file_data->table[i];
 		unsigned int this_files = min(nr_files, IORING_MAX_FILES_TABLE);
 
-		table->files = kcalloc(this_files, sizeof(struct file *),
+		table->files[i] = kcalloc(this_files, sizeof(*table->files[i]),
 					GFP_KERNEL);
-		if (!table->files)
+		if (!table->files[i])
 			break;
 		nr_files -= this_files;
 	}
@@ -7445,7 +7443,7 @@ static bool io_alloc_file_tables(struct io_rsrc_data *file_data,
 	if (i == nr_tables)
 		return true;
 
-	io_free_file_tables(file_data, nr_tables * IORING_MAX_FILES_TABLE);
+	io_free_file_tables(table, nr_tables * IORING_MAX_FILES_TABLE);
 	return false;
 }
 
@@ -7613,9 +7611,8 @@ static int io_sqe_files_register(struct io_ring_ctx *ctx, void __user *arg,
 	if (!file_data)
 		return -ENOMEM;
 	ctx->file_data = file_data;
-
 	ret = -ENOMEM;
-	if (!io_alloc_file_tables(file_data, nr_args))
+	if (!io_alloc_file_tables(&ctx->file_table, nr_args))
 		goto out_free;
 
 	for (i = 0; i < nr_args; i++, ctx->nr_user_files++) {
@@ -7643,7 +7640,7 @@ static int io_sqe_files_register(struct io_ring_ctx *ctx, void __user *arg,
 			fput(file);
 			goto out_fput;
 		}
-		io_fixed_file_set(io_fixed_file_slot(file_data, i), file);
+		io_fixed_file_set(io_fixed_file_slot(&ctx->file_table, i), file);
 	}
 
 	ret = io_sqe_files_scm(ctx);
@@ -7660,7 +7657,7 @@ out_fput:
 		if (file)
 			fput(file);
 	}
-	io_free_file_tables(file_data, nr_args);
+	io_free_file_tables(&ctx->file_table, nr_args);
 	ctx->nr_user_files = 0;
 out_free:
 	kfree(ctx->file_data);
@@ -7756,7 +7753,7 @@ static int __io_sqe_files_update(struct io_ring_ctx *ctx,
 			continue;
 
 		i = array_index_nospec(up->offset + done, ctx->nr_user_files);
-		file_slot = io_fixed_file_slot(ctx->file_data, i);
+		file_slot = io_fixed_file_slot(&ctx->file_table, i);
 
 		if (file_slot->file_ptr) {
 			file = (struct file *)(file_slot->file_ptr & FFS_MASK);