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cciss: change the way we notify scsi midlayer of tape drives
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This patch changes way we notify the scsi layer that something has changed
on the SCSI tape side of the driver. The user can now just tell the driver
to rescan a particular controller rather than having to know the SCSI nexus
to echo into the SCSI mid-layer.

Signed-off-by: Stephen M. Cameron <scameron@beardog.cca.cpqcorp.net>
Signed-off-by: Mike Miller <mike.miller@hp.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
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Mike Miller authored and Jens Axboe committed Aug 6, 2008
1 parent eece695 commit f4a93bc
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Showing 2 changed files with 124 additions and 54 deletions.
21 changes: 6 additions & 15 deletions Documentation/cciss.txt
View file
Original file line number Diff line number Diff line change
Expand Up @@ -112,27 +112,18 @@ Hot plug support for SCSI tape drives

Hot plugging of SCSI tape drives is supported, with some caveats.
The cciss driver must be informed that changes to the SCSI bus
have been made, in addition to and prior to informing the SCSI
mid layer. This may be done via the /proc filesystem. For example:
have been made. This may be done via the /proc filesystem.
For example:

echo "rescan" > /proc/scsi/cciss0/1

This causes the adapter to query the adapter about changes to the
physical SCSI buses and/or fibre channel arbitrated loop and the
This causes the driver to query the adapter about changes to the
physical SCSI buses and/or fibre channel arbitrated loop and the
driver to make note of any new or removed sequential access devices
or medium changers. The driver will output messages indicating what
devices have been added or removed and the controller, bus, target and
lun used to address the device. Once this is done, the SCSI mid layer
can be informed of changes to the virtual SCSI bus which the driver
presents to it in the usual way. For example:

echo scsi add-single-device 3 2 1 0 > /proc/scsi/scsi

to add a device on controller 3, bus 2, target 1, lun 0. Note that
the driver makes an effort to preserve the devices positions
in the virtual SCSI bus, so if you are only moving tape drives
around on the same adapter and not adding or removing tape drives
from the adapter, informing the SCSI mid layer may not be necessary.
lun used to address the device. It then notifies the SCSI mid layer
of these changes.

Note that the naming convention of the /proc filesystem entries
contains a number in addition to the driver name. (E.g. "cciss0"
Expand Down
157 changes: 118 additions & 39 deletions drivers/block/cciss_scsi.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -358,10 +358,15 @@ find_bus_target_lun(int ctlr, int *bus, int *target, int *lun)
}
return (!found);
}
struct scsi2map {
char scsi3addr[8];
int bus, target, lun;
};

static int
cciss_scsi_add_entry(int ctlr, int hostno,
unsigned char *scsi3addr, int devtype)
unsigned char *scsi3addr, int devtype,
struct scsi2map *added, int *nadded)
{
/* assumes hba[ctlr]->scsi_ctlr->lock is held */
int n = ccissscsi[ctlr].ndevices;
Expand All @@ -375,6 +380,12 @@ cciss_scsi_add_entry(int ctlr, int hostno,
sd = &ccissscsi[ctlr].dev[n];
if (find_bus_target_lun(ctlr, &sd->bus, &sd->target, &sd->lun) != 0)
return -1;

added[*nadded].bus = sd->bus;
added[*nadded].target = sd->target;
added[*nadded].lun = sd->lun;
(*nadded)++;

memcpy(&sd->scsi3addr[0], scsi3addr, 8);
sd->devtype = devtype;
ccissscsi[ctlr].ndevices++;
Expand All @@ -390,14 +401,19 @@ cciss_scsi_add_entry(int ctlr, int hostno,
}

static void
cciss_scsi_remove_entry(int ctlr, int hostno, int entry)
cciss_scsi_remove_entry(int ctlr, int hostno, int entry,
struct scsi2map *removed, int *nremoved)
{
/* assumes hba[ctlr]->scsi_ctlr->lock is held */
int i;
struct cciss_scsi_dev_t sd;

if (entry < 0 || entry >= CCISS_MAX_SCSI_DEVS_PER_HBA) return;
sd = ccissscsi[ctlr].dev[entry];
removed[*nremoved].bus = sd.bus;
removed[*nremoved].target = sd.target;
removed[*nremoved].lun = sd.lun;
(*nremoved)++;
for (i=entry;i<ccissscsi[ctlr].ndevices-1;i++)
ccissscsi[ctlr].dev[i] = ccissscsi[ctlr].dev[i+1];
ccissscsi[ctlr].ndevices--;
Expand All @@ -417,6 +433,26 @@ cciss_scsi_remove_entry(int ctlr, int hostno, int entry)
(a)[1] == (b)[1] && \
(a)[0] == (b)[0])

static void fixup_botched_add(int ctlr, char *scsi3addr)
{
/* called when scsi_add_device fails in order to re-adjust */
/* ccissscsi[] to match the mid layer's view. */
unsigned long flags;
int i, j;
CPQ_TAPE_LOCK(ctlr, flags);
for (i = 0; i < ccissscsi[ctlr].ndevices; i++) {
if (memcmp(scsi3addr,
ccissscsi[ctlr].dev[i].scsi3addr, 8) == 0) {
for (j = i; j < ccissscsi[ctlr].ndevices-1; j++)
ccissscsi[ctlr].dev[j] =
ccissscsi[ctlr].dev[j+1];
ccissscsi[ctlr].ndevices--;
break;
}
}
CPQ_TAPE_UNLOCK(ctlr, flags);
}

static int
adjust_cciss_scsi_table(int ctlr, int hostno,
struct cciss_scsi_dev_t sd[], int nsds)
Expand All @@ -429,13 +465,33 @@ adjust_cciss_scsi_table(int ctlr, int hostno,
int i,j, found, changes=0;
struct cciss_scsi_dev_t *csd;
unsigned long flags;
struct scsi2map *added, *removed;
int nadded, nremoved;
struct Scsi_Host *sh = NULL;

added = kzalloc(sizeof(*added) * CCISS_MAX_SCSI_DEVS_PER_HBA,
GFP_KERNEL);
removed = kzalloc(sizeof(*removed) * CCISS_MAX_SCSI_DEVS_PER_HBA,
GFP_KERNEL);

if (!added || !removed) {
printk(KERN_WARNING "cciss%d: Out of memory in "
"adjust_cciss_scsi_table\n", ctlr);
goto free_and_out;
}

CPQ_TAPE_LOCK(ctlr, flags);

if (hostno != -1) /* if it's not the first time... */
sh = ((struct cciss_scsi_adapter_data_t *)
hba[ctlr]->scsi_ctlr)->scsi_host;

/* find any devices in ccissscsi[] that are not in
sd[] and remove them from ccissscsi[] */

i = 0;
nremoved = 0;
nadded = 0;
while(i<ccissscsi[ctlr].ndevices) {
csd = &ccissscsi[ctlr].dev[i];
found=0;
Expand All @@ -455,17 +511,25 @@ adjust_cciss_scsi_table(int ctlr, int hostno,
/* printk("cciss%d: %s device c%db%dt%dl%d removed.\n",
ctlr, scsi_device_type(csd->devtype), hostno,
csd->bus, csd->target, csd->lun); */
cciss_scsi_remove_entry(ctlr, hostno, i);
/* note, i not incremented */
cciss_scsi_remove_entry(ctlr, hostno, i,
removed, &nremoved);
/* remove ^^^, hence i not incremented */
}
else if (found == 1) { /* device is different kind */
changes++;
printk("cciss%d: device c%db%dt%dl%d type changed "
"(device type now %s).\n",
ctlr, hostno, csd->bus, csd->target, csd->lun,
scsi_device_type(csd->devtype));
cciss_scsi_remove_entry(ctlr, hostno, i,
removed, &nremoved);
/* remove ^^^, hence i not incremented */
if (cciss_scsi_add_entry(ctlr, hostno,
&sd[j].scsi3addr[0], sd[j].devtype,
added, &nadded) != 0)
/* we just removed one, so add can't fail. */
BUG();
csd->devtype = sd[j].devtype;
i++; /* so just move along. */
} else /* device is same as it ever was, */
i++; /* so just move along. */
}
Expand All @@ -489,7 +553,9 @@ adjust_cciss_scsi_table(int ctlr, int hostno,
if (!found) {
changes++;
if (cciss_scsi_add_entry(ctlr, hostno,
&sd[i].scsi3addr[0], sd[i].devtype) != 0)

&sd[i].scsi3addr[0], sd[i].devtype,
added, &nadded) != 0)
break;
} else if (found == 1) {
/* should never happen... */
Expand All @@ -501,9 +567,50 @@ adjust_cciss_scsi_table(int ctlr, int hostno,
}
CPQ_TAPE_UNLOCK(ctlr, flags);

if (!changes)
printk("cciss%d: No device changes detected.\n", ctlr);
/* Don't notify scsi mid layer of any changes the first time through */
/* (or if there are no changes) scsi_scan_host will do it later the */
/* first time through. */
if (hostno == -1 || !changes)
goto free_and_out;

/* Notify scsi mid layer of any removed devices */
for (i = 0; i < nremoved; i++) {
struct scsi_device *sdev =
scsi_device_lookup(sh, removed[i].bus,
removed[i].target, removed[i].lun);
if (sdev != NULL) {
scsi_remove_device(sdev);
scsi_device_put(sdev);
} else {
/* We don't expect to get here. */
/* future cmds to this device will get selection */
/* timeout as if the device was gone. */
printk(KERN_WARNING "cciss%d: didn't find "
"c%db%dt%dl%d\n for removal.",
ctlr, hostno, removed[i].bus,
removed[i].target, removed[i].lun);
}
}

/* Notify scsi mid layer of any added devices */
for (i = 0; i < nadded; i++) {
int rc;
rc = scsi_add_device(sh, added[i].bus,
added[i].target, added[i].lun);
if (rc == 0)
continue;
printk(KERN_WARNING "cciss%d: scsi_add_device "
"c%db%dt%dl%d failed, device not added.\n",
ctlr, hostno,
added[i].bus, added[i].target, added[i].lun);
/* now we have to remove it from ccissscsi, */
/* since it didn't get added to scsi mid layer */
fixup_botched_add(ctlr, added[i].scsi3addr);
}

free_and_out:
kfree(added);
kfree(removed);
return 0;
}

Expand Down Expand Up @@ -1354,32 +1461,6 @@ cciss_unregister_scsi(int ctlr)
kfree(sa);
}

static int
cciss_register_scsi(int ctlr)
{
unsigned long flags;

CPQ_TAPE_LOCK(ctlr, flags);

/* Since this is really a block driver, the SCSI core may not be
initialized at init time, in which case, calling scsi_register_host
would hang. Instead, we do it later, via /proc filesystem
and rc scripts, when we know SCSI core is good to go. */

/* Only register if SCSI devices are detected. */
if (ccissscsi[ctlr].ndevices != 0) {
((struct cciss_scsi_adapter_data_t *)
hba[ctlr]->scsi_ctlr)->registered = 1;
CPQ_TAPE_UNLOCK(ctlr, flags);
return cciss_scsi_detect(ctlr);
}
CPQ_TAPE_UNLOCK(ctlr, flags);
printk(KERN_INFO
"cciss%d: No appropriate SCSI device detected, "
"SCSI subsystem not engaged.\n", ctlr);
return 0;
}

static int
cciss_engage_scsi(int ctlr)
{
Expand All @@ -1391,15 +1472,15 @@ cciss_engage_scsi(int ctlr)
sa = (struct cciss_scsi_adapter_data_t *) hba[ctlr]->scsi_ctlr;
stk = &sa->cmd_stack;

if (((struct cciss_scsi_adapter_data_t *)
hba[ctlr]->scsi_ctlr)->registered) {
if (sa->registered) {
printk("cciss%d: SCSI subsystem already engaged.\n", ctlr);
spin_unlock_irqrestore(CCISS_LOCK(ctlr), flags);
return ENXIO;
}
sa->registered = 1;
spin_unlock_irqrestore(CCISS_LOCK(ctlr), flags);
cciss_update_non_disk_devices(ctlr, -1);
cciss_register_scsi(ctlr);
cciss_scsi_detect(ctlr);
return 0;
}

Expand Down Expand Up @@ -1493,7 +1574,5 @@ static int cciss_eh_abort_handler(struct scsi_cmnd *scsicmd)
/* If no tape support, then these become defined out of existence */

#define cciss_scsi_setup(cntl_num)
#define cciss_unregister_scsi(ctlr)
#define cciss_register_scsi(ctlr)

#endif /* CONFIG_CISS_SCSI_TAPE */

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