From: NeilBrown 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 Signed-off-by: Jonathan Brassow Signed-off-by: Mike Snitzer Signed-off-by: Alasdair G Kergon --- drivers/md/dm-raid.c | 18 ++++++++++++++++-- drivers/md/dm-table.c | 14 ++++++++++++++ include/linux/device-mapper.h | 11 +++++++++++ 2 files changed, 25 insertions(+) Index: linux-2.6.37/drivers/md/dm-table.c =================================================================== --- linux-2.6.37.orig/drivers/md/dm-table.c +++ linux-2.6.37/drivers/md/dm-table.c @@ -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 **re 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_ta 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_tab 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; } Index: linux-2.6.37/include/linux/device-mapper.h =================================================================== --- linux-2.6.37.orig/include/linux/device-mapper.h +++ linux-2.6.37/include/linux/device-mapper.h @@ -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); @@ -269,6 +275,11 @@ int dm_table_add_target(struct dm_table 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. */ int dm_table_complete(struct dm_table *t);