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dm persistent data: add threshold callback to space map

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Add a threshold callback function to the persistent data space map
interface for a subsequent patch to use.

dm-thin and dm-cache are interested in knowing when they're getting
low on metadata or data blocks.  This patch introduces a new method
for registering a callback against a threshold.

Signed-off-by: Joe Thornber <ejt@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
This commit is contained in:
Joe Thornber 2013-05-10 14:37:20 +01:00 committed by Alasdair G Kergon
parent 24347e9595
commit 7c3d3f2a87
3 changed files with 29 additions and 3 deletions
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3
drivers/md/persistent-data/dm-space-map-disk.c
View file

@ -248,7 +248,8 @@ static struct dm_space_map ops = {
.new_block = sm_disk_new_block,
.commit = sm_disk_commit,
.root_size = sm_disk_root_size,
.copy_root = sm_disk_copy_root
.copy_root = sm_disk_copy_root,
.register_threshold_callback = NULL
};
struct dm_space_map *dm_sm_disk_create(struct dm_transaction_manager *tm,

6
drivers/md/persistent-data/dm-space-map-metadata.c
View file

@ -391,7 +391,8 @@ static struct dm_space_map ops = {
.new_block = sm_metadata_new_block,
.commit = sm_metadata_commit,
.root_size = sm_metadata_root_size,
.copy_root = sm_metadata_copy_root
.copy_root = sm_metadata_copy_root,
.register_threshold_callback = NULL
};
/*----------------------------------------------------------------*/
@ -513,7 +514,8 @@ static struct dm_space_map bootstrap_ops = {
.new_block = sm_bootstrap_new_block,
.commit = sm_bootstrap_commit,
.root_size = sm_bootstrap_root_size,
.copy_root = sm_bootstrap_copy_root
.copy_root = sm_bootstrap_copy_root,
.register_threshold_callback = NULL
};
/*----------------------------------------------------------------*/

23
drivers/md/persistent-data/dm-space-map.h
View file

@ -9,6 +9,8 @@
#include "dm-block-manager.h"
typedef void (*dm_sm_threshold_fn)(void *context);
/*
* struct dm_space_map keeps a record of how many times each block in a device
* is referenced. It needs to be fixed on disk as part of the transaction.
@ -59,6 +61,15 @@ struct dm_space_map {
*/
int (*root_size)(struct dm_space_map *sm, size_t *result);
int (*copy_root)(struct dm_space_map *sm, void *copy_to_here_le, size_t len);
/*
* You can register one threshold callback which is edge-triggered
* when the free space in the space map drops below the threshold.
*/
int (*register_threshold_callback)(struct dm_space_map *sm,
dm_block_t threshold,
dm_sm_threshold_fn fn,
void *context);
};
/*----------------------------------------------------------------*/
@ -131,4 +142,16 @@ static inline int dm_sm_copy_root(struct dm_space_map *sm, void *copy_to_here_le
return sm->copy_root(sm, copy_to_here_le, len);
}
static inline int dm_sm_register_threshold_callback(struct dm_space_map *sm,
dm_block_t threshold,
dm_sm_threshold_fn fn,
void *context)
{
if (sm->register_threshold_callback)
return sm->register_threshold_callback(sm, threshold, fn, context);
return -EINVAL;
}
#endif /* _LINUX_DM_SPACE_MAP_H */