On 02/14/2017 12:51 PM, Jeff Moyer wrote:
> Goldwyn Rodrigues <rgoldwyn@xxxxxxx> writes:
>
>> From: Goldwyn Rodrigues <rgoldwyn@xxxxxxxx>
>>
>> This flag informs kernel to bail out if an AIO request will block
>> for reasons such as file allocations, or a writeback triggered
>> by direct I/O.
>>
>> IOCB_FLAG_NONBLOCKING is translated to IOCB_NONBLOCKING for
>> iocb->ki_flags.
>
> This shouldn't be an option, it should be the default. This is what
> users want when using this interface to begin with.
>
:)
While I appreciate the appreciation for the efforts, we can't let
existing applications fail which would receive -EAGAIN for all aio/dio
requests they are sending to the kernel and expecting to complete.
> Cheers,
> Jeff
>
>>
>> Signed-off-by: Goldwyn Rodrigues <rgoldwyn@xxxxxxxx>
>> ---
>> fs/aio.c | 3 +++
>> include/linux/fs.h | 1 +
>> include/uapi/linux/aio_abi.h | 3 +++
>> 3 files changed, 7 insertions(+)
>>
>> diff --git a/fs/aio.c b/fs/aio.c
>> index 428484f..0725756 100644
>> --- a/fs/aio.c
>> +++ b/fs/aio.c
>> @@ -1551,6 +1551,9 @@ static int io_submit_one(struct kioctx *ctx, struct iocb __user *user_iocb,
>> req->common.ki_flags |= IOCB_EVENTFD;
>> }
>>
>> + if (iocb->aio_flags & IOCB_FLAG_NONBLOCKING)
>> + req->common.ki_flags |= IOCB_NONBLOCKING;
>> +
>> ret = put_user(KIOCB_KEY, &user_iocb->aio_key);
>> if (unlikely(ret)) {
>> pr_debug("EFAULT: aio_key\n");
>> diff --git a/include/linux/fs.h b/include/linux/fs.h
>> index dc0478c..bfbaba6 100644
>> --- a/include/linux/fs.h
>> +++ b/include/linux/fs.h
>> @@ -322,6 +322,7 @@ struct writeback_control;
>> #define IOCB_DSYNC (1 << 4)
>> #define IOCB_SYNC (1 << 5)
>> #define IOCB_WRITE (1 << 6)
>> +#define IOCB_NONBLOCKING (1 << 7)
>>
>> struct kiocb {
>> struct file *ki_filp;
>> diff --git a/include/uapi/linux/aio_abi.h b/include/uapi/linux/aio_abi.h
>> index bb2554f..03ce4c2 100644
>> --- a/include/uapi/linux/aio_abi.h
>> +++ b/include/uapi/linux/aio_abi.h
>> @@ -51,8 +51,11 @@ enum {
>> *
>> * IOCB_FLAG_RESFD - Set if the "aio_resfd" member of the "struct iocb"
>> * is valid.
>> + * IOCB_FLAG_NOBLOCK - Set if the user wants the iocb to fail if it would block
>> + * for operations such as disk allocation.
>> */
>> #define IOCB_FLAG_RESFD (1 << 0)
>> +#define IOCB_FLAG_NONBLOCKING (1 << 1)
>>
>> /* read() from /dev/aio returns these structures. */
>> struct io_event {
>
--
Goldwyn
