Add basic support just to get the per-port group state. This support does not account of state transitioning, sdev port group reconfiguration, etc, required for full support.
libmultipath callbacks scsi_mpath_is_optimized() and scsi_mpath_is_disabled() are updated to take account of the ALUA-provided path information. As before, for no ALUA support (and scsi_multipath_always on) we assume that the paths are all optimized. Much of this code in scsi_mpath_alua_init() is copied from scsi_dh_alua.c, originally authored by Hannes Reinecke. Signed-off-by: John Garry <[email protected]> --- drivers/scsi/scsi_multipath.c | 163 ++++++++++++++++++++++++++++++++-- include/scsi/scsi_multipath.h | 3 + 2 files changed, 160 insertions(+), 6 deletions(-) diff --git a/drivers/scsi/scsi_multipath.c b/drivers/scsi/scsi_multipath.c index 1489c7e979167..0a314080bf0a5 100644 --- a/drivers/scsi/scsi_multipath.c +++ b/drivers/scsi/scsi_multipath.c @@ -4,6 +4,7 @@ * */ +#include <scsi/scsi_alua.h> #include <scsi/scsi_cmnd.h> #include <scsi/scsi_driver.h> #include <scsi/scsi_proto.h> @@ -346,18 +347,29 @@ static bool scsi_mpath_is_disabled(struct mpath_device *mpath_device) to_scsi_mpath_device(mpath_device); struct scsi_device *sdev = scsi_mpath_dev->sdev; enum scsi_device_state sdev_state = sdev->sdev_state; + int alua_state = scsi_mpath_dev->alua_state; if (sdev_state == SDEV_RUNNING || sdev_state == SDEV_CANCEL) return false; - return true; + if (alua_state == SCSI_ACCESS_STATE_OPTIMAL || + alua_state == SCSI_ACCESS_STATE_ACTIVE) + return true; + + return false; } static bool scsi_mpath_is_optimized(struct mpath_device *mpath_device) { + struct scsi_mpath_device *scsi_mpath_dev = + to_scsi_mpath_device(mpath_device); + if (scsi_mpath_is_disabled(mpath_device)) return false; - return true; + if (scsi_mpath_dev->alua_state == SCSI_ACCESS_STATE_OPTIMAL) + return true; + return false; + } /* Until we have ALUA support, we're always optimised */ @@ -366,7 +378,7 @@ static enum mpath_access_state scsi_mpath_get_access_state( { if (scsi_mpath_is_disabled(mpath_device)) return MPATH_STATE_INVALID; - return MPATH_STATE_OPTIMIZED; + return scsi_mpath_is_optimized(mpath_device); } static bool scsi_mpath_available_path(struct mpath_device *mpath_device, bool *available) @@ -579,16 +591,147 @@ static void scsi_multipath_sdev_uninit(struct scsi_device *sdev) sdev->scsi_mpath_dev = NULL; } +static int scsi_mpath_alua_init(struct scsi_device *sdev) +{ + struct scsi_mpath_device *scsi_mpath_dev = sdev->scsi_mpath_dev; + struct scsi_sense_hdr sense_hdr; + int len, k, off, bufflen = ALUA_RTPG_SIZE; + unsigned char *desc, *buff; + unsigned int tpg_desc_tbl_off; + int group_id, rel_port = -1; + bool ext_hdr_unsupp = false; + int ret; + + group_id = scsi_vpd_tpg_id(sdev, &rel_port); + if (group_id < 0) { + /* + * Internal error; TPGS supported but required + * VPD identification descriptors not present. + * Disable ALUA support. + */ + sdev_printk(KERN_INFO, sdev, + "%s: No target port descriptors found\n", + __func__); + return -EIO; + } + + buff = kzalloc(bufflen, GFP_KERNEL); + if (!buff) + return -ENOMEM; + retry: + ret = submit_rtpg(sdev, buff, bufflen, &sense_hdr, + ext_hdr_unsupp); + + if (ret) { + if (ret < 0 || !scsi_sense_valid(&sense_hdr)) { + sdev_printk(KERN_INFO, sdev, + "%s: rtpg failed, result %d\n", + __func__, ret); + kfree(buff); + if (ret < 0) + return -EBUSY; + if (host_byte(ret) == DID_NO_CONNECT) + return -ENODEV; + return -EIO; + } + + /* + * submit_rtpg() has failed on existing arrays + * when requesting extended header info, and + * the array doesn't support extended headers, + * even though it shouldn't according to T10. + * The retry without rtpg_ext_hdr_req set + * handles this. + * Note: some arrays return a sense key of ILLEGAL_REQUEST + * with ASC 00h if they don't support the extended header. + */ + if (ext_hdr_unsupp && + sense_hdr.sense_key == ILLEGAL_REQUEST) { + ext_hdr_unsupp = true; + goto retry; + } + /* + * If the array returns with 'ALUA state transition' + * sense code here it cannot return RTPG data during + * transition. So set the state to 'transitioning' directly. + */ + if (sense_hdr.sense_key == NOT_READY && + sense_hdr.asc == 0x04 && sense_hdr.ascq == 0x0a) + goto out; + + /* + * Retry on any other UNIT ATTENTION occurred. + */ + if (sense_hdr.sense_key == UNIT_ATTENTION) { + scsi_print_sense_hdr(sdev, __func__, &sense_hdr); + kfree(buff); + return -EAGAIN; + } + sdev_printk(KERN_ERR, sdev, "%s: rtpg failed\n", + __func__); + scsi_print_sense_hdr(sdev, __func__, &sense_hdr); + kfree(buff); + return -EIO; + } + + len = get_unaligned_be32(&buff[0]) + 4; + + if (len > bufflen) { + /* Resubmit with the correct length */ + kfree(buff); + bufflen = len; + buff = kmalloc(bufflen, GFP_KERNEL); + if (!buff) { + /* Temporary failure, bypass */ + return -EBUSY; + } + goto retry; + } + + if ((buff[4] & RTPG_FMT_MASK) == RTPG_FMT_EXT_HDR) + tpg_desc_tbl_off = 8; + else + tpg_desc_tbl_off = 4; + + for (k = tpg_desc_tbl_off, desc = buff + tpg_desc_tbl_off; + k < len; + k += off, desc += off) { + u16 group_id_found = get_unaligned_be16(&desc[2]); + + if (group_id_found == group_id) { + int valid_states, state, pref; + + state = desc[0] & 0x0f; + pref = desc[0] >> 7; + valid_states = desc[1]; + + alua_print_info(sdev, group_id, state, pref, valid_states); + + scsi_mpath_dev->alua_state = state; + scsi_mpath_dev->alua_pref = pref; + scsi_mpath_dev->alua_valid_states = valid_states; + goto out; + } + + off = 8 + (desc[7] * 4); + } + +out: + kfree(buff); + return 0; +} + int scsi_mpath_dev_alloc(struct scsi_device *sdev) { struct scsi_mpath_head *scsi_mpath_head; - int ret; + int ret, tpgs; if (!scsi_multipath) return 0; - if (!scsi_device_tpgs(sdev) && !scsi_multipath_always) { - sdev_printk(KERN_NOTICE, sdev, "tpgs are required for multipath support\n"); + tpgs = alua_check_tpgs(sdev); + if (!(tpgs & TPGS_MODE_IMPLICIT) && !scsi_multipath_always) { + sdev_printk(KERN_DEBUG, sdev, "IMPLICIT TPGS are required for multipath support\n"); return 0; } @@ -622,6 +765,14 @@ int scsi_mpath_dev_alloc(struct scsi_device *sdev) sdev->scsi_mpath_dev->scsi_mpath_head = scsi_mpath_head; found: + if (tpgs & TPGS_MODE_IMPLICIT) { + ret = scsi_mpath_alua_init(sdev); + if (ret) + goto out_put_head; + } else { + sdev->scsi_mpath_dev->alua_state = SCSI_ACCESS_STATE_OPTIMAL; + } + sdev->scsi_mpath_dev->index = ida_alloc(&scsi_mpath_head->ida, GFP_KERNEL); if (sdev->scsi_mpath_dev->index < 0) { ret = sdev->scsi_mpath_dev->index; diff --git a/include/scsi/scsi_multipath.h b/include/scsi/scsi_multipath.h index 2011447f482d6..7c7ee2fb7def7 100644 --- a/include/scsi/scsi_multipath.h +++ b/include/scsi/scsi_multipath.h @@ -38,6 +38,9 @@ struct scsi_mpath_device { int index; atomic_t nr_active; struct scsi_mpath_head *scsi_mpath_head; + int alua_state; + int alua_pref; + int alua_valid_states; char device_id_str[SCSI_MPATH_DEVICE_ID_LEN]; }; -- 2.43.5
