On 22/12/2020 02:10, Noah Goldstein wrote:
> On Sun, Dec 20, 2020 at 03:18:05PM +0000, Pavel Begunkov wrote:
>> On 20/12/2020 06:50, noah wrote:> From: noah <goldstein.n@xxxxxxxxx>
>>>
>>> This patch makes it so that specify a file descriptor value of -2 will
>>> skip updating the corresponding fixed file index.
>>>
>>> This will allow for users to reduce the number of syscalls necessary
>>> to update a sparse file range when using the fixed file option.
>>
>> Answering the github thread -- it's indeed a simple change, I had it the
>> same day you posted the issue. See below it's a bit cleaner. However, I
>> want to first review "io_uring: buffer registration enhancements", and
>> if it's good, for easier merging/etc I'd rather prefer to let it go
>> first (even if partially).
Noah, want to give it a try? I've just sent a prep patch, with it you
can implement it cleaner with one continue.
>>
>> diff --git a/fs/io_uring.c b/fs/io_uring.c
>> index 941fe9b64fd9..b3ae9d5da17e 100644
>> --- a/fs/io_uring.c
>> +++ b/fs/io_uring.c
>> @@ -7847,9 +7847,8 @@ static int __io_sqe_files_update(struct io_ring_ctx *ctx,
>> if (IS_ERR(ref_node))
>> return PTR_ERR(ref_node);
>>
>> - done = 0;
>> fds = u64_to_user_ptr(up->fds);
>> - while (nr_args) {
>> + for (done = 0; done < nr_args; done++) {
>> struct fixed_file_table *table;
>> unsigned index;
>>
>> @@ -7858,7 +7857,10 @@ static int __io_sqe_files_update(struct io_ring_ctx *ctx,
>> err = -EFAULT;
>> break;
>> }
>> - i = array_index_nospec(up->offset, ctx->nr_user_files);
>> + if (fd == IORING_REGISTER_FILES_SKIP)
>> + continue;
>> +
>> + i = array_index_nospec(up->offset + done, ctx->nr_user_files);
>> table = &ctx->file_data->table[i >> IORING_FILE_TABLE_SHIFT];
>> index = i & IORING_FILE_TABLE_MASK;
>> if (table->files[index]) {
>> @@ -7896,9 +7898,6 @@ static int __io_sqe_files_update(struct io_ring_ctx *ctx,
>> break;
>> }
>> }
>> - nr_args--;
>> - done++;
>> - up->offset++;
>> }
>>
>> if (needs_switch) {
--
Pavel Begunkov
