On 10/17/2013 12:28 AM, Nicholas A. Bellinger wrote:
> On Wed, 2013-10-16 at 09:25 +0200, Hannes Reinecke wrote:
>> Add infrastructure for referrals.
>>
>> Signed-off-by: Hannes Reinecke <h...@suse.de>
>> ---
>> drivers/target/target_core_alua.c | 151
>> ++++++++++++++++++++++++++++++++++
>> drivers/target/target_core_alua.h | 4 +-
>> drivers/target/target_core_configfs.c | 12 ++-
>> drivers/target/target_core_device.c | 2 +
>> drivers/target/target_core_sbc.c | 5 +-
>> drivers/target/target_core_spc.c | 20 +++++
>> include/scsi/scsi.h | 1 +
>> include/target/target_core_base.h | 18 ++++
>> 8 files changed, 209 insertions(+), 4 deletions(-)
>>
>> diff --git a/drivers/target/target_core_alua.c
>> b/drivers/target/target_core_alua.c
>> index 166bee6..8f66146 100644
>> --- a/drivers/target/target_core_alua.c
>> +++ b/drivers/target/target_core_alua.c
>> @@ -56,6 +56,75 @@ static LIST_HEAD(lu_gps_list);
>> struct t10_alua_lu_gp *default_lu_gp;
>>
>> /*
>> + * REPORT REFERRALS
>> + *
>> + * See sbc3r35 section 5.23
>> + */
>> +sense_reason_t
>> +target_emulate_report_referrals(struct se_cmd *cmd)
>> +{
>> + struct se_device *dev = cmd->se_dev;
>> + struct t10_alua_lba_map *map;
>> + struct t10_alua_lba_map_member *map_mem;
>> + unsigned char *buf;
>> + u32 rd_len = 0, off;
>> +
>> + if (cmd->data_length < 4) {
>> + pr_warn("REPORT REFERRALS allocation length %u too"
>> + " small\n", cmd->data_length);
>> + return TCM_INVALID_CDB_FIELD;
>> + }
>> +
>> + buf = transport_kmap_data_sg(cmd);
>> + if (!buf)
>> + return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
>> +
>> + off = 4;
>> + spin_lock(&dev->t10_alua.lba_map_lock);
>> + if (list_empty(&dev->t10_alua.lba_map_list)) {
>> + spin_unlock(&dev->t10_alua.lba_map_lock);
>> + transport_kunmap_data_sg(cmd);
>> +
>> + return TCM_UNSUPPORTED_SCSI_OPCODE;
>> + }
>> +
>> + list_for_each_entry(map, &dev->t10_alua.lba_map_list,
>> + lba_map_list) {
>> + int desc_num = off + 3;
>> + int pg_num;
>> +
>> + off += 4;
>> + put_unaligned_be64(map->lba_map_first_lba, &buf[off]);
>> + off += 8;
>> + put_unaligned_be64(map->lba_map_last_lba, &buf[off]);
>> + off += 8;
>> + rd_len += 20;
>> + pg_num = 0;
>> + list_for_each_entry(map_mem, &map->lba_map_mem_list,
>> + lba_map_mem_list) {
>> + buf[off++] = map_mem->lba_map_mem_alua_state & 0x0f;
>> + off++;
>> + buf[off++] = (map_mem->lba_map_mem_alua_pg_id >> 8) &
>> 0xff;
>> + buf[off++] = (map_mem->lba_map_mem_alua_pg_id & 0xff);
>> + rd_len += 4;
>> + pg_num++;
>> + }
>> + buf[desc_num] = pg_num;
>> + }
>> + spin_unlock(&dev->t10_alua.lba_map_lock);
>> +
>
> For both of these list walks, there needs to be a check against offset
> vs. ->data_length to know when the available payload length has been
> exhausted..
>
Right. Will be fixing it up.
[ .. ]
>> diff --git a/drivers/target/target_core_spc.c
>> b/drivers/target/target_core_spc.c
>> index e39d442..282b5bb 100644
>> --- a/drivers/target/target_core_spc.c
>> +++ b/drivers/target/target_core_spc.c
>> @@ -476,6 +476,11 @@ spc_emulate_evpd_86(struct se_cmd *cmd, unsigned char
>> *buf)
>> /* If WriteCache emulation is enabled, set V_SUP */
>> if (spc_check_dev_wce(dev))
>> buf[6] = 0x01;
>> + /* If an LBA map is present set R_SUP */
>> + spin_lock(&cmd->se_dev->t10_alua.lba_map_lock);
>> + if (!list_empty(&dev->t10_alua.lba_map_list))
>> + buf[8] = 0x10;
>> + spin_unlock(&cmd->se_dev->t10_alua.lba_map_lock);
>> return 0;
>> }
>
> Is there ever a case where R_SUP should be reported, but lba_map_list is
> empty..?
>
Not that I can see. If R_SUP is set it means the 'REPORT REFERRALS'
is supported. And 'REPORT REFERRALS' without a map is pretty much
pointless.
> How about a se_device attribute called 'emulate_referrals' to determine
> when to report R_SUP..? Otherwise, perhaps using the se_lun -> se_port
> -> sep_alua_tg_pt_gp_mem -> tg_pt_gp provided bit for
> tg_pt_gp_alua_supported_states instead..?
>
I was thinking about the very same thing, but then figured it was
easier to equal R_SUP with !list_empty(lba_map_list) instead of
having a separate flag.
Or crawling indirections just to find the very same information ...
>>
>> @@ -627,6 +632,20 @@ spc_emulate_evpd_b2(struct se_cmd *cmd, unsigned char
>> *buf)
>> return 0;
>> }
>>
>> +/* Referrals VPD page */
>> +static sense_reason_t
>> +spc_emulate_evpd_b3(struct se_cmd *cmd, unsigned char *buf)
>> +{
>> + struct se_device *dev = cmd->se_dev;
>> +
>> + buf[0] = dev->transport->get_device_type(dev);
>> + buf[3] = 0x0c;
>> + put_unaligned_be32(dev->t10_alua.lba_map_segment_size, &buf[8]);
>> + put_unaligned_be32(dev->t10_alua.lba_map_segment_size, &buf[12]);
>> +
>
> Typo.. Offset for byte 12 should be the lba_map_segment_multiplier..
>
Oops ...
Will be fixing up the patch.
Cheers,
Hannes
--
Dr. Hannes Reinecke zSeries & Storage
h...@suse.de +49 911 74053 688
SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 Nürnberg
GF: J. Hawn, J. Guild, F. Imendörffer, HRB 16746 (AG Nürnberg)
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