On 10/27/22 11:16, Damien Le Moal wrote:
On 10/27/22 17:11, Hannes Reinecke wrote:
On 10/27/22 03:34, Damien Le Moal wrote:
On 10/25/22 19:18, John Garry wrote:
Currently the per-ata device sdev is allocated as part of the scsi
target
scan, which is after the ata port probe.
However it is useful to have the sdev available in the port probe. As an
example of an advantage, if the request queue is available in the probe
(which it would be if the sdev is available), then it is possible to use
a SCSI cmnd for ATA internal commands. The benefit of this is then we
can
put the ATA qc structure in the SCSI cmnd private data. It will also be
useful if we want to send ATA internal commands as requests.
Export scsi_target_reap() so that it can be used to put the extra
reference we get when allocating the sdev.
Signed-off-by: John Garry <john.garry@xxxxxxxxxx>
---
drivers/ata/libata-eh.c | 1 +
drivers/ata/libata-scsi.c | 23 +++++++++--------------
drivers/scsi/scsi_scan.c | 1 +
3 files changed, 11 insertions(+), 14 deletions(-)
diff --git a/drivers/ata/libata-eh.c b/drivers/ata/libata-eh.c
index 08e11bc312c2..1ed5b1b64792 100644
--- a/drivers/ata/libata-eh.c
+++ b/drivers/ata/libata-eh.c
@@ -3446,6 +3446,7 @@ static int ata_eh_schedule_probe(struct
ata_device *dev)
ata_eh_detach_dev(dev);
ata_dev_init(dev);
+ ata_scsi_setup_sdev(dev);
ehc->did_probe_mask |= (1 << dev->devno);
ehc->i.action |= ATA_EH_RESET;
ehc->saved_xfer_mode[dev->devno] = 0;
diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c
index efdba852e363..476e0ef4bd29 100644
--- a/drivers/ata/libata-scsi.c
+++ b/drivers/ata/libata-scsi.c
@@ -1109,7 +1109,12 @@ int ata_scsi_dev_config(struct scsi_device
*sdev, struct ata_device *dev)
if (dev->flags & ATA_DFLAG_TRUSTED)
sdev->security_supported = 1;
- dev->sdev = sdev;
+ /*
+ * Put extra reference which we get when allocating the starget
+ * initially
+ */
+ scsi_target_reap(scsi_target(sdev));
+
return 0;
}
@@ -4289,26 +4294,16 @@ void ata_scsi_scan_host(struct ata_port
*ap, int sync)
repeat:
ata_for_each_link(link, ap, EDGE) {
ata_for_each_dev(dev, link, ENABLED) {
- struct scsi_device *sdev;
+ struct Scsi_Host *shost = ap->scsi_host;
int channel = 0, id = 0;
- if (dev->sdev)
- continue;
-
if (ata_is_host_link(link))
id = dev->devno;
else
channel = link->pmp;
- sdev = __scsi_add_device(ap->scsi_host, channel, id, 0,
- NULL);
- if (!IS_ERR(sdev)) {
- dev->sdev = sdev;
- ata_scsi_assign_ofnode(dev, ap);
Is there something equivalent to what this function does inside
scsi_scan_target() ? I had a quick look but did not see anything...
Typically, the SCSI layer has two ways of scanning.
One it the old-style serial scanning (originating in the old SCSI
parallel model):
The scanning code will blindly scan _all_ devices up to max_luns, and
attach every device for which the scanning code returns 'OK'.
The other one is to issue REPORT_LUNS and scan all LUNs returned there.
Mapped to libata we would need to figure out a stable SCSI enumeration,
given that we have PMP and slave devices to content with.
To my knowledge we have ATA ports, each can have either a 'master' and
'slave' device, _or_ it be a PMP port when it can support up to 16
devices, right?
yes
Point being, master/slave and PMP are exclusive, right?
Never heard of pmp with ide cable :)
See?
So we can make the master as LUN 0, and the slave as LUN 1.
Yes, but isn't that a little wrong ? That would assume that the ata port
is the device and the ata devices the luns of that device. But beside
the "link busy" stuff that needs to be dealt with, master and slave are
independent devices, unlike LUNs. No ?
Well; technically, yes.
But we already enumerate the ata ports (which is typically done by the
hardware/PCI layer etc), and if we were try to model slave devices as
independent ports we would either have to insert a numbering (awkward)
or add a number at the en (even more awkward).
And the one key takeaway from the 'multiple actuators' discussion is
that LUNs _are_ independent (cf all the hoops they had to jump through
to define a command spanning several LUNs ...)(which, incidentally, we
could leverage here, too ...), and the target port really only serves as
an enumeration thingie to address the LUNs.
So we _could_ map the master device on LUN 0 and the slave device on LUN
1 with no loss of functionality, _but_ enable a consistent SCSI enumeration.
Cheers,
Hannes
--
Dr. Hannes Reinecke Kernel Storage Architect
hare@xxxxxxx +49 911 74053 688
SUSE Software Solutions GmbH, Maxfeldstr. 5, 90409 Nürnberg
HRB 36809 (AG Nürnberg), Geschäftsführer: Ivo Totev, Andrew
Myers, Andrew McDonald, Martje Boudien Moerman
