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>
This commit is contained in:
Pavel Begunkov
2022-06-25 11:55:38 +01:00
committed by Jens Axboe
parent e6130eba8a
commit 6e73dffbb9
6 changed files with 61 additions and 7 deletions

View File

@@ -3,9 +3,7 @@
#define IOU_FILE_TABLE_H
#include <linux/file.h>
struct io_ring_ctx;
struct io_kiocb;
#include <linux/io_uring_types.h>
/*
* FFS_SCM is only available on 64-bit archs, for 32-bit we just define it as 0
@@ -33,6 +31,9 @@ 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)
@@ -71,4 +72,17 @@ static inline void io_fixed_file_set(struct io_fixed_file *file_slot,
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