On Fri, 2011-05-27 at 12:07 -0700, Andy Grover wrote:
> Instead of relying on tcm core to allocate data buffers for the cmd,
> iscsi allocates them and then calls map_mem_to_cmd, which creates the
> core-specific se_mem list, and sets a flag so the core will not later
> try to also allocate memory for the cmd.
>
> Down the road, this will allow iscsi to handle the data buffer only with
> the buffer offset and length, and without relying on the se_mem list
> at all.
>
> Signed-off-by: Andy Grover <agrover@xxxxxxxxxx>
> ---
Loooks good. Committed as ef03f53150 with hch's recommendation to use
DIV_ROUND_UP() instead of the locally defined ceil().
Thanks,
--nab
> drivers/target/iscsi/iscsi_target.c | 81 ++++++++++++++++++++++++++++++
> drivers/target/iscsi/iscsi_target_core.h | 5 ++
> drivers/target/iscsi/iscsi_target_util.c | 11 ++++
> 3 files changed, 97 insertions(+), 0 deletions(-)
>
> diff --git a/drivers/target/iscsi/iscsi_target.c b/drivers/target/iscsi/iscsi_target.c
> index 79c2fd7..9e07dca 100644
> --- a/drivers/target/iscsi/iscsi_target.c
> +++ b/drivers/target/iscsi/iscsi_target.c
> @@ -979,6 +979,82 @@ static void iscsit_ack_from_expstatsn(struct iscsi_conn *conn, u32 exp_statsn)
> spin_unlock_bh(&conn->cmd_lock);
> }
>
> +#define ceil(x, y) \
> + ({ unsigned long __x = (x), __y = (y); (__x + __y - 1) / __y; })
> +
> +static int iscsit_alloc_buffs(struct iscsi_cmd *cmd)
> +{
> + u32 length = cmd->se_cmd.data_length;
> + struct scatterlist *sgl;
> + int nents = ceil(length, PAGE_SIZE);
> + int i = 0;
> + void *buf;
> + void *cur;
> + struct page *page;
> +
> + sgl = kzalloc(sizeof(*sgl) * nents, GFP_KERNEL);
> + if (!sgl)
> + return -ENOMEM;
> +
> + /*
> + * Allocate from slab if nonsg, but sgl should point
> + * to the malloced mem.
> + * We know we have to kfree it if t_task_buf is set.
> + * Alloc pages if sg.
> + */
> + if (cmd->se_cmd.se_cmd_flags & SCF_SCSI_CONTROL_NONSG_IO_CDB) {
> +
> + buf = kmalloc(length, GFP_KERNEL);
> + if (!buf)
> + return -ENOMEM;
> +
> + cur = buf;
> + while (length) {
> + int buf_size = min_t(int, length, PAGE_SIZE);
> +
> + sg_set_buf(&sgl[i], cur, buf_size);
> +
> + length -= buf_size;
> + cur += buf_size;
> + i++;
> + }
> + cmd->se_cmd.t_task_buf = buf;
> + cmd->t_mem = buf;
> +
> + } else {
> +
> + while (length) {
> + int buf_size = min_t(int, length, PAGE_SIZE);
> +
> + page = alloc_page(GFP_KERNEL);
> + if (!page)
> + goto page_alloc_failed;
> +
> + sg_set_page(&sgl[i], page, buf_size, 0);
> +
> + length -= buf_size;
> + i++;
> + }
> + }
> +
> + cmd->t_mem_sg = sgl;
> + cmd->t_mem_sg_nents = nents;
> +
> + /* BIDI ops not supported */
> +
> + /* make se_mem list from the memory */
> + transport_generic_map_mem_to_cmd(&cmd->se_cmd, sgl, nents, NULL, 0);
> +
> + return 0;
> +
> +page_alloc_failed:
> + while (i >= 0) {
> + __free_page(sg_page(&sgl[i]));
> + i--;
> + }
> + return -ENOMEM;
> +}
> +
> static int iscsit_handle_scsi_cmd(
> struct iscsi_conn *conn,
> unsigned char *buf)
> @@ -1249,6 +1325,11 @@ attach_cmd:
> goto after_immediate_data;
> }
>
> + ret = iscsit_alloc_buffs(cmd);
> + if (ret < 0) {
> + return ret;
> + }
> +
> /*
> * Immediate Data is present, send to the transport and block until
> * the underlying transport plugin has allocated the buffer to
> diff --git a/drivers/target/iscsi/iscsi_target_core.h b/drivers/target/iscsi/iscsi_target_core.h
> index 0eaf86b..d64cd30 100644
> --- a/drivers/target/iscsi/iscsi_target_core.h
> +++ b/drivers/target/iscsi/iscsi_target_core.h
> @@ -472,6 +472,11 @@ struct iscsi_cmd {
> /* Sense buffer that will be mapped into outgoing status */
> #define ISCSI_SENSE_BUFFER_LEN (TRANSPORT_SENSE_BUFFER + 2)
> unsigned char sense_buffer[ISCSI_SENSE_BUFFER_LEN];
> +
> + void *t_mem;
> + struct scatterlist *t_mem_sg;
> + u32 t_mem_sg_nents;
> +
> } ____cacheline_aligned;
>
> #define SE_CMD(cmd) (&(cmd)->se_cmd)
> diff --git a/drivers/target/iscsi/iscsi_target_util.c b/drivers/target/iscsi/iscsi_target_util.c
> index 612658a..6d770a4 100644
> --- a/drivers/target/iscsi/iscsi_target_util.c
> +++ b/drivers/target/iscsi/iscsi_target_util.c
> @@ -812,6 +812,17 @@ void iscsit_release_cmd(struct iscsi_cmd *cmd)
> kfree(cmd->tmr_req);
> kfree(cmd->iov_data);
>
> + /* see iscsit_alloc_buffs */
> + if (cmd->t_mem) {
> + kfree(cmd->t_mem);
> + } else {
> + int i;
> +
> + for (i = 0; i < cmd->t_mem_sg_nents; i++)
> + __free_page(sg_page(&cmd->t_mem_sg[i]));
> + }
> + kfree(cmd->t_mem_sg);
> +
> if (conn) {
> iscsit_remove_cmd_from_immediate_queue(cmd, conn);
> iscsit_remove_cmd_from_response_queue(cmd, conn);
> --
> 1.7.1
>
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