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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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1
fs/exofs/exofs.h
View file

@ -217,6 +217,7 @@ static inline void exofs_init_comps(struct ore_components *oc,
one_comp->obj.id = oid;
exofs_make_credential(one_comp->cred, &one_comp->obj);
oc->first_dev = 0;
oc->numdevs = sbi->layout.group_width * sbi->layout.mirrors_p1 *
sbi->layout.group_count;
oc->single_comp = EC_SINGLE_COMP;

4
fs/exofs/ore.c
View file

@ -62,6 +62,10 @@ static struct osd_obj_id *_ios_obj(struct ore_io_state *ios, unsigned index)
static struct osd_dev *_ios_od(struct ore_io_state *ios, unsigned index)
{
ORE_DBGMSG2("oc->first_dev=%d oc->numdevs=%d i=%d oc->ods=%p\n",
ios->oc->first_dev, ios->oc->numdevs, index,
ios->oc->ods);
return ore_comp_dev(ios->oc, index);
}

7
include/scsi/osd_ore.h
View file

@ -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 {