Adding write_same16 to CAM Target Layer

[bharat singh]

Hello,

I am trying to add write_same16 (block zero) support to my FC stack.
This i am trying to achieve by adding a hook in CTL layer, reading
start_LBA and no of blocks to fill with 0.

struct ctl_scsiio {
>-------struct ctl_io_hdr io_hdr;>------/* common to all I/O types */
>-------uint32_t   ext_sg_entries;>-----/* 0 = no S/G list, > 0 = num
entries */
>-------uint8_t>   *ext_data_ptr;>------/* data buffer or S/G list */
>-------uint32_t   ext_data_len;>-------/* Data transfer length */
>-------uint32_t   ext_data_filled;>----/* Amount of data filled so far */
>-------uint32_t   kern_sg_entries;>----/* 0 = no S/G list, > 0 = num
entries */
>-------uint32_t   rem_sg_entries;>-----/* 0 = no S/G list, > 0 = num
entries */
>-------uint8_t    *kern_data_ptr;>-----/* data buffer or S/G list */
>-------uint32_t   kern_data_len;>------/* Length of this S/G list/buffer */
>-------uint32_t   kern_total_len;>-----/* Total length of this transaction
*/
>-------uint32_t   kern_data_resid;>----/* Length left to transfer after
this*/
>-------uint32_t   kern_rel_offset;>----/* Byte Offset of this transfer */
>-------struct     scsi_sense_data sense_data;>-/* sense data */
>-------uint8_t>   sense_len;>-->-------/* Returned sense length */
>-------uint8_t>   scsi_status;>>-------/* SCSI status byte */
>-------uint8_t>   sense_residual;>-----/* sense residual length */
>-------uint32_t   residual;>--->-------/* data residual length */
>-------uint32_t   tag_num;>---->-------/* tag number */
>-------ctl_tag_type tag_type;>->-------/* simple, ordered, head of
queue,etc.*/
>-------uint8_t    cdb_len;>---->-------/* CDB length */
>-------uint8_t>   cdb[CTL_MAX_CDBLEN];>/* CDB */
>-------int>----   (*be_move_done)(union ctl_io *io); /* called by fe */
>-------int        (*io_cont)(union ctl_io *io); /* to continue processing
*/
>-------uint32_t   ctl_lun_masking_disabled; /* Disable lun mask checks for
ctladm calls */
};

For write_same16 initiators will send a block of 0s with start_LBA and no
of blocks. Assuming that I am trying to:
datalen = blocksize * num_blocks;
uint8_t * databuf = malloc(datalen);
bzero(databuf, 0, datalen);
ctsio->kern_data_ptr = dataptr;
ctsio->kern_data_len = datalen;
lbalen.lba = lba;
lbalen.len = num_blocks;
memcpy(ctsio->io_hdr.ctl_private[CTL_PRIV_LBA_LEN].bytes, &lbalen,
sizeof(lbalen));
ret = lun->backend->data_submit((union ctl_io *)ctsio);

but it's failing in ISP layer with data overflow. My initiator is sending
2048 blocks of size 512B each and a payload of 512 bytes in data-out buffer.
isp0: isp_target_start_ctio: [0x120154] data overflow by 1048064 bytes
(1:3:0:1): WRITE SAME(16). CDB: 93 00 00 00 00 00 00 1f e8 00 00 00 08 00
00 00

Have any one done changes to the CTL read/write path, am I missing
something regarding buffer population.
Thanks for the help in advance.

Thanks,
Bharat