+static int nvme_init_dma_buf_io_ctx(struct block_device *bdev,

• 		    struct dma_buf_io_ctx *ctx)
  

Please stick to two-tab indents for function declaration continuation for the nvme code to keep the code easy to maintain.

+#if defined(CONFIG_DMA_SHARED_BUFFER)

This should be good old #ifdef. Same in a few other places over the series.

Modulo these minor nits the patch looks good.