[Patch v9 07/10] block: Add fops atomic write support

[Keith Busch]

On Thu, Jun 20, 2024 at 12:53:56PM +0000, John Garry wrote:
> Support atomic writes by submitting a single BIO with the REQ_ATOMIC set.
> 
> It must be ensured that the atomic write adheres to its rules, like
> naturally aligned offset, so call blkdev_dio_invalid() ->
> blkdev_atomic_write_valid() [with renaming blkdev_dio_unaligned() to
> blkdev_dio_invalid()] for this purpose. The BIO submission path currently
> checks for atomic writes which are too large, so no need to check here.
> 
> In blkdev_direct_IO(), if the nr_pages exceeds BIO_MAX_VECS, then we cannot
> produce a single BIO, so error in this case.
> 
> Finally set FMODE_CAN_ATOMIC_WRITE when the bdev can support atomic writes
> and the associated file flag is for O_DIRECT.

Looks good.

Reviewed-by: Keith Busch <kbusch at kernel.org>