linux-stable/io_uring/filetable.c
Jens Axboe 340f634aa4 io_uring/filetable: don't unnecessarily clear/reset bitmap
If we're updating an existing slot, we clear the slot bitmap only to
set it again right after. Just leave the bit set rather than toggle
it off and on, and move the unused slot setting into the branch of
not already having a file occupy this slot.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
2024-05-08 08:27:45 -06:00

175 lines
3.9 KiB
C

// SPDX-License-Identifier: GPL-2.0
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/file.h>
#include <linux/mm.h>
#include <linux/slab.h>
#include <linux/nospec.h>
#include <linux/io_uring.h>
#include <uapi/linux/io_uring.h>
#include "io_uring.h"
#include "rsrc.h"
#include "filetable.h"
static int io_file_bitmap_get(struct io_ring_ctx *ctx)
{
struct io_file_table *table = &ctx->file_table;
unsigned long nr = ctx->file_alloc_end;
int ret;
if (!table->bitmap)
return -ENFILE;
do {
ret = find_next_zero_bit(table->bitmap, nr, table->alloc_hint);
if (ret != nr)
return ret;
if (table->alloc_hint == ctx->file_alloc_start)
break;
nr = table->alloc_hint;
table->alloc_hint = ctx->file_alloc_start;
} while (1);
return -ENFILE;
}
bool io_alloc_file_tables(struct io_file_table *table, unsigned nr_files)
{
table->files = kvcalloc(nr_files, sizeof(table->files[0]),
GFP_KERNEL_ACCOUNT);
if (unlikely(!table->files))
return false;
table->bitmap = bitmap_zalloc(nr_files, GFP_KERNEL_ACCOUNT);
if (unlikely(!table->bitmap)) {
kvfree(table->files);
return false;
}
return true;
}
void io_free_file_tables(struct io_file_table *table)
{
kvfree(table->files);
bitmap_free(table->bitmap);
table->files = NULL;
table->bitmap = NULL;
}
static int io_install_fixed_file(struct io_ring_ctx *ctx, struct file *file,
u32 slot_index)
__must_hold(&req->ctx->uring_lock)
{
struct io_fixed_file *file_slot;
int ret;
if (io_is_uring_fops(file))
return -EBADF;
if (!ctx->file_data)
return -ENXIO;
if (slot_index >= ctx->nr_user_files)
return -EINVAL;
slot_index = array_index_nospec(slot_index, ctx->nr_user_files);
file_slot = io_fixed_file_slot(&ctx->file_table, slot_index);
if (file_slot->file_ptr) {
ret = io_queue_rsrc_removal(ctx->file_data, slot_index,
io_slot_file(file_slot));
if (ret)
return ret;
file_slot->file_ptr = 0;
} else {
io_file_bitmap_set(&ctx->file_table, slot_index);
}
*io_get_tag_slot(ctx->file_data, slot_index) = 0;
io_fixed_file_set(file_slot, file);
return 0;
}
int __io_fixed_fd_install(struct io_ring_ctx *ctx, struct file *file,
unsigned int file_slot)
{
bool alloc_slot = file_slot == IORING_FILE_INDEX_ALLOC;
int ret;
if (alloc_slot) {
ret = io_file_bitmap_get(ctx);
if (unlikely(ret < 0))
return ret;
file_slot = ret;
} else {
file_slot--;
}
ret = io_install_fixed_file(ctx, file, file_slot);
if (!ret && alloc_slot)
ret = file_slot;
return ret;
}
/*
* Note when io_fixed_fd_install() returns error value, it will ensure
* fput() is called correspondingly.
*/
int io_fixed_fd_install(struct io_kiocb *req, unsigned int issue_flags,
struct file *file, unsigned int file_slot)
{
struct io_ring_ctx *ctx = req->ctx;
int ret;
io_ring_submit_lock(ctx, issue_flags);
ret = __io_fixed_fd_install(ctx, file, file_slot);
io_ring_submit_unlock(ctx, issue_flags);
if (unlikely(ret < 0))
fput(file);
return ret;
}
int io_fixed_fd_remove(struct io_ring_ctx *ctx, unsigned int offset)
{
struct io_fixed_file *file_slot;
int ret;
if (unlikely(!ctx->file_data))
return -ENXIO;
if (offset >= ctx->nr_user_files)
return -EINVAL;
offset = array_index_nospec(offset, ctx->nr_user_files);
file_slot = io_fixed_file_slot(&ctx->file_table, offset);
if (!file_slot->file_ptr)
return -EBADF;
ret = io_queue_rsrc_removal(ctx->file_data, offset,
io_slot_file(file_slot));
if (ret)
return ret;
file_slot->file_ptr = 0;
io_file_bitmap_clear(&ctx->file_table, offset);
return 0;
}
int io_register_file_alloc_range(struct io_ring_ctx *ctx,
struct io_uring_file_index_range __user *arg)
{
struct io_uring_file_index_range range;
u32 end;
if (copy_from_user(&range, arg, sizeof(range)))
return -EFAULT;
if (check_add_overflow(range.off, range.len, &end))
return -EOVERFLOW;
if (range.resv || end > ctx->nr_user_files)
return -EINVAL;
io_file_table_set_alloc_range(ctx, range.off, range.len);
return 0;
}