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dm: introduce target callbacks and congestion callback

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DM currently implements congestion checking by checking on congestion
in each component device.  For raid456 we need to also check if the
stripe cache is congested.

Add per-target congestion checker callback support.

Extending the target_callbacks structure with additional callback
functions allows for establishing multiple callbacks per-target (a
callback is also needed for unplug).

Cc: linux-raid@vger.kernel.org
Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: Jonathan Brassow <jbrassow@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
This commit is contained in:
NeilBrown 2011-01-13 20:00:01 +00:00 committed by Alasdair G Kergon
parent 4e2d19e46b
commit 9d357b0787
2 changed files with 25 additions and 0 deletions
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14
drivers/md/dm-table.c
View File

@ -71,6 +71,8 @@ struct dm_table {
void *event_context;
struct dm_md_mempools *mempools;
struct list_head target_callbacks;
};
/*
@ -204,6 +206,7 @@ int dm_table_create(struct dm_table **result, fmode_t mode,
return -ENOMEM;
INIT_LIST_HEAD(&t->devices);
INIT_LIST_HEAD(&t->target_callbacks);
atomic_set(&t->holders, 0);
t->discards_supported = 1;
@ -1225,10 +1228,17 @@ int dm_table_resume_targets(struct dm_table *t)
return 0;
}
void dm_table_add_target_callbacks(struct dm_table *t, struct dm_target_callbacks *cb)
{
list_add(&cb->list, &t->target_callbacks);
}
EXPORT_SYMBOL_GPL(dm_table_add_target_callbacks);
int dm_table_any_congested(struct dm_table *t, int bdi_bits)
{
struct dm_dev_internal *dd;
struct list_head *devices = dm_table_get_devices(t);
struct dm_target_callbacks *cb;
int r = 0;
list_for_each_entry(dd, devices, list) {
@ -1243,6 +1253,10 @@ int dm_table_any_congested(struct dm_table *t, int bdi_bits)
bdevname(dd->dm_dev.bdev, b));
}
list_for_each_entry(cb, &t->target_callbacks, list)
if (cb->congested_fn)
r |= cb->congested_fn(cb, bdi_bits);
return r;
}

11
include/linux/device-mapper.h
View File

@ -193,6 +193,12 @@ struct dm_target {
char *error;
};
/* Each target can link one of these into the table */
struct dm_target_callbacks {
struct list_head list;
int (*congested_fn) (struct dm_target_callbacks *, int);
};
int dm_register_target(struct target_type *t);
void dm_unregister_target(struct target_type *t);
@ -268,6 +274,11 @@ int dm_table_create(struct dm_table **result, fmode_t mode,
int dm_table_add_target(struct dm_table *t, const char *type,
sector_t start, sector_t len, char *params);
/*
* Target_ctr should call this if it needs to add any callbacks.
*/
void dm_table_add_target_callbacks(struct dm_table *t, struct dm_target_callbacks *cb);
/*
* Finally call this to make the table ready for use.
*/