On 5/9/22 7:26 AM, Hao Xu wrote:
> ? 2022/5/9 ??7:49, Jens Axboe ??:
>> In preparation for adding a basic allocator for direct descriptors,
>> add helpers that set/clear whether a file slot is used.
>>
>> Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
>> ---
>> fs/io_uring.c | 37 +++++++++++++++++++++++++++++++++++--
>> 1 file changed, 35 insertions(+), 2 deletions(-)
>>
>> diff --git a/fs/io_uring.c b/fs/io_uring.c
>> index b6d491c9a25f..6eac6629e7d4 100644
>> --- a/fs/io_uring.c
>> +++ b/fs/io_uring.c
>> @@ -257,6 +257,7 @@ struct io_rsrc_put {
>> struct io_file_table {
>> struct io_fixed_file *files;
>> + unsigned long *bitmap;
>> };
>> struct io_rsrc_node {
>> @@ -7573,6 +7574,7 @@ static inline struct file *io_file_get_fixed(struct io_kiocb *req, int fd,
>> /* mask in overlapping REQ_F and FFS bits */
>> req->flags |= (file_ptr << REQ_F_SUPPORT_NOWAIT_BIT);
>> io_req_set_rsrc_node(req, ctx, 0);
>> + WARN_ON_ONCE(file && !test_bit(fd, ctx->file_table.bitmap));
>> out:
>> io_ring_submit_unlock(ctx, issue_flags);
>> return file;
>> @@ -8639,13 +8641,35 @@ static 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);
>> - return !!table->files;
>> + 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;
>> }
>> static void io_free_file_tables(struct io_file_table *table)
>> {
>> kvfree(table->files);
>> + bitmap_free(table->bitmap);
>> table->files = NULL;
>> + table->bitmap = NULL;
>> +}
>> +
>> +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);
>> +}
>> +
>> +static inline void io_file_bitmap_clear(struct io_file_table *table, int bit)
>> +{
>> + __clear_bit(bit, table->bitmap);
>> }
>> static void __io_sqe_files_unregister(struct io_ring_ctx *ctx)
>> @@ -8660,6 +8684,7 @@ static void __io_sqe_files_unregister(struct io_ring_ctx *ctx)
>> continue;
>> if (io_fixed_file_slot(&ctx->file_table, i)->file_ptr & FFS_SCM)
>> continue;
>> + io_file_bitmap_clear(&ctx->file_table, i);
>> fput(file);
>> }
>> #endif
>> @@ -9063,6 +9088,7 @@ static int io_sqe_files_register(struct io_ring_ctx *ctx, void __user *arg,
>> }
>> file_slot = io_fixed_file_slot(&ctx->file_table, i);
>> io_fixed_file_set(file_slot, file);
>> + io_file_bitmap_set(&ctx->file_table, i);
>> }
>> io_rsrc_node_switch(ctx, NULL);
>> @@ -9123,6 +9149,7 @@ static int io_install_fixed_file(struct io_kiocb *req, struct file *file,
>> if (ret)
>> goto err;
>> file_slot->file_ptr = 0;
>> + io_file_bitmap_clear(&ctx->file_table, slot_index);
>> needs_switch = true;
>> }
>> @@ -9130,13 +9157,16 @@ static int io_install_fixed_file(struct io_kiocb *req, struct file *file,
>> if (!ret) {
>> *io_get_tag_slot(ctx->file_data, slot_index) = 0;
>> io_fixed_file_set(file_slot, file);
>> + io_file_bitmap_set(&ctx->file_table, slot_index);
> [1]
>> }
>> err:
>> if (needs_switch)
>> io_rsrc_node_switch(ctx, ctx->file_data);
>> io_ring_submit_unlock(ctx, issue_flags);
>> - if (ret)
>> + if (ret) {
>> + io_file_bitmap_clear(&ctx->file_table, slot_index);
> We don't need to clean it, since we get here only when we didn't
> run [1], which means we haven't set it.
Good point, agree. I'll drop that one.
--
Jens Axboe
