linux/io_uring/filetable.h
Pavel Begunkov 6e73dffbb9 io_uring: let to set a range for file slot allocation
From recently io_uring provides an option to allocate a file index for
operation registering fixed files. However, it's utterly unusable with
mixed approaches when for a part of files the userspace knows better
where to place it, as it may race and users don't have any sane way to
pick a slot and hoping it will not be taken.

Let the userspace to register a range of fixed file slots in which the
auto-allocation happens. The use case is splittting the fixed table in
two parts, where on of them is used for auto-allocation and another for
slot-specified operations.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/66ab0394e436f38437cf7c44676e1920d09687ad.1656154403.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-07-24 18:39:16 -06:00

89 lines
2.5 KiB
C

// SPDX-License-Identifier: GPL-2.0
#ifndef IOU_FILE_TABLE_H
#define IOU_FILE_TABLE_H
#include <linux/file.h>
#include <linux/io_uring_types.h>
/*
* FFS_SCM is only available on 64-bit archs, for 32-bit we just define it as 0
* and define IO_URING_SCM_ALL. For this case, we use SCM for all files as we
* can't safely always dereference the file when the task has exited and ring
* cleanup is done. If a file is tracked and part of SCM, then unix gc on
* process exit may reap it before __io_sqe_files_unregister() is run.
*/
#define FFS_NOWAIT 0x1UL
#define FFS_ISREG 0x2UL
#if defined(CONFIG_64BIT)
#define FFS_SCM 0x4UL
#else
#define IO_URING_SCM_ALL
#define FFS_SCM 0x0UL
#endif
#define FFS_MASK ~(FFS_NOWAIT|FFS_ISREG|FFS_SCM)
bool io_alloc_file_tables(struct io_file_table *table, unsigned nr_files);
void io_free_file_tables(struct io_file_table *table);
int io_fixed_fd_install(struct io_kiocb *req, unsigned int issue_flags,
struct file *file, unsigned int file_slot);
int __io_fixed_fd_install(struct io_ring_ctx *ctx, struct file *file,
unsigned int file_slot);
int io_fixed_fd_remove(struct io_ring_ctx *ctx, unsigned int offset);
int io_register_file_alloc_range(struct io_ring_ctx *ctx,
struct io_uring_file_index_range __user *arg);
unsigned int io_file_get_flags(struct file *file);
static inline void io_file_bitmap_clear(struct io_file_table *table, int bit)
{
__clear_bit(bit, table->bitmap);
table->alloc_hint = bit;
}
static inline void io_file_bitmap_set(struct io_file_table *table, int bit)
{
WARN_ON_ONCE(test_bit(bit, table->bitmap));
__set_bit(bit, table->bitmap);
table->alloc_hint = bit + 1;
}
static inline struct io_fixed_file *
io_fixed_file_slot(struct io_file_table *table, unsigned i)
{
return &table->files[i];
}
static inline struct file *io_file_from_index(struct io_file_table *table,
int index)
{
struct io_fixed_file *slot = io_fixed_file_slot(table, index);
return (struct file *) (slot->file_ptr & FFS_MASK);
}
static inline void io_fixed_file_set(struct io_fixed_file *file_slot,
struct file *file)
{
unsigned long file_ptr = (unsigned long) file;
file_ptr |= io_file_get_flags(file);
file_slot->file_ptr = file_ptr;
}
static inline void io_reset_alloc_hint(struct io_ring_ctx *ctx)
{
ctx->file_table.alloc_hint = ctx->file_alloc_start;
}
static inline void io_file_table_set_alloc_range(struct io_ring_ctx *ctx,
unsigned off, unsigned len)
{
ctx->file_alloc_start = off;
ctx->file_alloc_end = off + len;
io_reset_alloc_hint(ctx);
}
#endif