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ore: Support for partial component table

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Users like the objlayout-driver would like to only pass
a partial device table that covers the IO in question.
For example exofs divides the file into raid-group-sized
chunks and only serves group_width number of devices at
a time.

The partiality is communicated by setting
ore_componets->first_dev and the array covers all logical
devices from oc->first_dev upto (oc->first_dev + oc->numdevs)

The ore_comp_dev() API receives a logical device index
and returns the actual present device in the table.
An out-of-range dev_index will BUG.

Logical device index is the theoretical device index as if
all the devices of a file are present. .i.e:
	total_devs = group_width * mirror_p1 * group_count
	0 <= dev_index < total_devs

Signed-off-by: Boaz Harrosh <bharrosh@panasas.com>
This commit is contained in:
Boaz Harrosh
2011-09-28 12:04:23 +03:00
parent bbf9a31bba
commit 3bd9856857
3 changed files with 9 additions and 3 deletions
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7
include/scsi/osd_ore.h
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@@ -49,6 +49,7 @@ struct ore_dev {
};
struct ore_components {
unsigned first_dev; /* First logical device no */
unsigned numdevs; /* Num of devices in array */
/* If @single_comp == EC_SINGLE_COMP, @comps points to a single
* component. else there are @numdevs components
@@ -70,14 +71,14 @@ struct ore_components {
static inline struct osd_dev *ore_comp_dev(
const struct ore_components *oc, unsigned i)
{
BUG_ON(oc->numdevs <= i);
return oc->ods[i]->od;
BUG_ON((i < oc->first_dev) || (oc->first_dev + oc->numdevs <= i));
return oc->ods[i - oc->first_dev]->od;
}
static inline void ore_comp_set_dev(
struct ore_components *oc, unsigned i, struct osd_dev *od)
{
oc->ods[i]->od = od;
oc->ods[i - oc->first_dev]->od = od;
}
struct ore_striping_info {