Re: [PATCH-v2 13/17] target/file: Add DIF protection support to fd_execute_rw

[Sagi Grimberg <sagig@dev.mellanox.co.il>]

On 1/19/2014 4:44 AM, Nicholas A. Bellinger wrote:
> From: Nicholas Bellinger <nab@linux-iscsi.org>
>
> This patch adds support for DIF protection into fd_execute_rw() code
> for WRITE/READ I/O using sbc_dif_verify_[write,read]() logic.
>
> It adds fd_do_prot_rw() for handling interface with FILEIO PI, and
> uses a locally allocated fd_prot->prot_buf + fd_prot->prot_sg for
> interacting with SBC DIF verify emulation code.
>
> Cc: Martin K. Petersen <martin.petersen@oracle.com>
> Cc: Christoph Hellwig <hch@lst.de>
> Cc: Hannes Reinecke <hare@suse.de>
> Cc: Sagi Grimberg <sagig@mellanox.com>
> Cc: Or Gerlitz <ogerlitz@mellanox.com>
> Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
> ---
>   drivers/target/target_core_file.c |  119 ++++++++++++++++++++++++++++++++++++-
>   drivers/target/target_core_file.h |    5 ++
>   2 files changed, 123 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/target/target_core_file.c b/drivers/target/target_core_file.c
> index 119d519..aaba7c5 100644
> --- a/drivers/target/target_core_file.c
> +++ b/drivers/target/target_core_file.c
> @@ -257,6 +257,72 @@ static void fd_free_device(struct se_device *dev)
>   	kfree(fd_dev);
>   }
>   
> +static int fd_do_prot_rw(struct se_cmd *cmd, struct fd_prot *fd_prot,
> +			 int is_write)
> +{
> +	struct se_device *se_dev = cmd->se_dev;
> +	struct fd_dev *dev = FD_DEV(se_dev);
> +	struct file *prot_fd = dev->fd_prot_file;
> +	struct scatterlist *sg;
> +	loff_t pos = (cmd->t_task_lba * se_dev->prot_length);
> +	unsigned char *buf;
> +	u32 prot_size, len, size;
> +	int rc, ret = 1, i;
> +
> +	prot_size = (cmd->data_length / se_dev->dev_attrib.block_size) *
> +		     se_dev->prot_length;
> +
> +	if (!is_write) {
> +		fd_prot->prot_buf = vzalloc(prot_size);
> +		if (!fd_prot->prot_buf) {
> +			pr_err("Unable to allocate fd_prot->prot_buf\n");
> +			return -ENOMEM;
> +		}
> +		buf = fd_prot->prot_buf;
> +
> +		fd_prot->prot_sg_nents = cmd->t_prot_nents;
> +		fd_prot->prot_sg = kzalloc(sizeof(struct scatterlist) *
> +					   fd_prot->prot_sg_nents, GFP_KERNEL);
> +		if (!fd_prot->prot_sg) {
> +			pr_err("Unable to allocate fd_prot->prot_sg\n");
> +			vfree(fd_prot->prot_buf);
> +			return -ENOMEM;
> +		}
> +		size = prot_size;
> +
> +		for_each_sg(fd_prot->prot_sg, sg, fd_prot->prot_sg_nents, i) {
> +
> +			len = min_t(u32, PAGE_SIZE, size);
> +			sg_set_buf(sg, buf, len);
> +			size -= len;
> +			buf += len;
> +		}
> +	}
> +
> +	if (is_write) {
> +		rc = kernel_write(prot_fd, fd_prot->prot_buf, prot_size, pos);
> +		if (rc < 0 || prot_size != rc) {
> +			pr_err("kernel_write() for fd_do_prot_rw failed:"
> +			       " %d\n", rc);
> +			ret = -EINVAL;
> +		}
> +	} else {
> +		rc = kernel_read(prot_fd, pos, fd_prot->prot_buf, prot_size);
> +		if (rc < 0) {
> +			pr_err("kernel_read() for fd_do_prot_rw failed:"
> +			       " %d\n", rc);
> +			ret = -EINVAL;
> +		}
> +	}
> +
> +	if (is_write || ret < 0) {
> +		kfree(fd_prot->prot_sg);
> +		vfree(fd_prot->prot_buf);
> +	}
> +
> +	return ret;
> +}
> +
>   static int fd_do_rw(struct se_cmd *cmd, struct scatterlist *sgl,
>   		u32 sgl_nents, int is_write)
>   {
> @@ -551,6 +617,8 @@ fd_execute_rw(struct se_cmd *cmd, struct scatterlist *sgl, u32 sgl_nents,
>   	      enum dma_data_direction data_direction)
>   {
>   	struct se_device *dev = cmd->se_dev;
> +	struct fd_prot fd_prot;
> +	sense_reason_t rc;
>   	int ret = 0;
>   
>   	/*
> @@ -558,8 +626,48 @@ fd_execute_rw(struct se_cmd *cmd, struct scatterlist *sgl, u32 sgl_nents,
>   	 * physical memory addresses to struct iovec virtual memory.
>   	 */
>   	if (data_direction == DMA_FROM_DEVICE) {

Maybe its better to export this one to a separate function? 
fd_execute_prot_rw()? just a nit...

> +		memset(&fd_prot, 0, sizeof(struct fd_prot));
> +
> +		if (cmd->prot_type) {
> +			ret = fd_do_prot_rw(cmd, &fd_prot, false);
> +			if (ret < 0)
> +				return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
> +		}
> +
>   		ret = fd_do_rw(cmd, sgl, sgl_nents, 0);
> +
> +		if (ret > 0 && cmd->prot_type) {
> +			u32 sectors = cmd->data_length / dev->dev_attrib.block_size;
> +
> +			rc = sbc_dif_verify_read(cmd, cmd->t_task_lba, sectors,
> +						 0, fd_prot.prot_sg, 0);
> +			if (rc) {
> +				kfree(fd_prot.prot_sg);
> +				vfree(fd_prot.prot_buf);
> +				return rc;
> +			}
> +			kfree(fd_prot.prot_sg);
> +			vfree(fd_prot.prot_buf);
> +		}
>   	} else {
> +		memset(&fd_prot, 0, sizeof(struct fd_prot));
> +
> +		if (cmd->prot_type) {
> +			u32 sectors = cmd->data_length / dev->dev_attrib.block_size;
> +
> +			ret = fd_do_prot_rw(cmd, &fd_prot, false);
> +			if (ret < 0)
> +				return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
> +
> +			rc = sbc_dif_verify_write(cmd, cmd->t_task_lba, sectors,
> +						  0, fd_prot.prot_sg, 0);
> +			if (rc) {
> +				kfree(fd_prot.prot_sg);
> +				vfree(fd_prot.prot_buf);
> +				return rc;
> +			}
> +		}
> +
>   		ret = fd_do_rw(cmd, sgl, sgl_nents, 1);
>   		/*
>   		 * Perform implicit vfs_fsync_range() for fd_do_writev() ops
> @@ -576,10 +684,19 @@ fd_execute_rw(struct se_cmd *cmd, struct scatterlist *sgl, u32 sgl_nents,
>   
>   			vfs_fsync_range(fd_dev->fd_file, start, end, 1);
>   		}
> +
> +		if (ret > 0 && cmd->prot_type) {
> +			ret = fd_do_prot_rw(cmd, &fd_prot, true);
> +			if (ret < 0)
> +				return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
> +		}
>   	}
>   
> -	if (ret < 0)
> +	if (ret < 0) {
> +		kfree(fd_prot.prot_sg);
> +		vfree(fd_prot.prot_buf);
>   		return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
> +	}
>   
>   	if (ret)
>   		target_complete_cmd(cmd, SAM_STAT_GOOD);
> diff --git a/drivers/target/target_core_file.h b/drivers/target/target_core_file.h
> index 583691e..97e5e7d 100644
> --- a/drivers/target/target_core_file.h
> +++ b/drivers/target/target_core_file.h
> @@ -18,6 +18,11 @@
>   #define FDBD_HAS_BUFFERED_IO_WCE 0x04
>   #define FDBD_FORMAT_UNIT_SIZE	2048
>   
> +struct fd_prot {
> +	unsigned char	*prot_buf;
> +	struct scatterlist *prot_sg;
> +	u32 prot_sg_nents;
> +};
>   
>   struct fd_dev {
>   	struct se_device dev;