7c3d3f2a87
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>
158 lines
4.2 KiB
C
158 lines
4.2 KiB
C
/*
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* Copyright (C) 2011 Red Hat, Inc.
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*
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* This file is released under the GPL.
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*/
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#ifndef _LINUX_DM_SPACE_MAP_H
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#define _LINUX_DM_SPACE_MAP_H
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#include "dm-block-manager.h"
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typedef void (*dm_sm_threshold_fn)(void *context);
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/*
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* struct dm_space_map keeps a record of how many times each block in a device
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* is referenced. It needs to be fixed on disk as part of the transaction.
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*/
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struct dm_space_map {
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void (*destroy)(struct dm_space_map *sm);
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/*
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* You must commit before allocating the newly added space.
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*/
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int (*extend)(struct dm_space_map *sm, dm_block_t extra_blocks);
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/*
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* Extensions do not appear in this count until after commit has
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* been called.
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*/
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int (*get_nr_blocks)(struct dm_space_map *sm, dm_block_t *count);
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/*
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* Space maps must never allocate a block from the previous
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* transaction, in case we need to rollback. This complicates the
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* semantics of get_nr_free(), it should return the number of blocks
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* that are available for allocation _now_. For instance you may
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* have blocks with a zero reference count that will not be
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* available for allocation until after the next commit.
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*/
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int (*get_nr_free)(struct dm_space_map *sm, dm_block_t *count);
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int (*get_count)(struct dm_space_map *sm, dm_block_t b, uint32_t *result);
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int (*count_is_more_than_one)(struct dm_space_map *sm, dm_block_t b,
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int *result);
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int (*set_count)(struct dm_space_map *sm, dm_block_t b, uint32_t count);
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int (*commit)(struct dm_space_map *sm);
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int (*inc_block)(struct dm_space_map *sm, dm_block_t b);
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int (*dec_block)(struct dm_space_map *sm, dm_block_t b);
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/*
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* new_block will increment the returned block.
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*/
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int (*new_block)(struct dm_space_map *sm, dm_block_t *b);
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/*
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* The root contains all the information needed to fix the space map.
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* Generally this info is small, so squirrel it away in a disk block
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* along with other info.
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*/
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int (*root_size)(struct dm_space_map *sm, size_t *result);
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int (*copy_root)(struct dm_space_map *sm, void *copy_to_here_le, size_t len);
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/*
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* You can register one threshold callback which is edge-triggered
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* when the free space in the space map drops below the threshold.
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*/
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int (*register_threshold_callback)(struct dm_space_map *sm,
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dm_block_t threshold,
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dm_sm_threshold_fn fn,
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void *context);
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};
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/*----------------------------------------------------------------*/
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static inline void dm_sm_destroy(struct dm_space_map *sm)
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{
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sm->destroy(sm);
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}
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static inline int dm_sm_extend(struct dm_space_map *sm, dm_block_t extra_blocks)
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{
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return sm->extend(sm, extra_blocks);
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}
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static inline int dm_sm_get_nr_blocks(struct dm_space_map *sm, dm_block_t *count)
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{
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return sm->get_nr_blocks(sm, count);
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}
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static inline int dm_sm_get_nr_free(struct dm_space_map *sm, dm_block_t *count)
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{
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return sm->get_nr_free(sm, count);
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}
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static inline int dm_sm_get_count(struct dm_space_map *sm, dm_block_t b,
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uint32_t *result)
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{
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return sm->get_count(sm, b, result);
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}
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static inline int dm_sm_count_is_more_than_one(struct dm_space_map *sm,
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dm_block_t b, int *result)
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{
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return sm->count_is_more_than_one(sm, b, result);
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}
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static inline int dm_sm_set_count(struct dm_space_map *sm, dm_block_t b,
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uint32_t count)
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{
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return sm->set_count(sm, b, count);
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}
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static inline int dm_sm_commit(struct dm_space_map *sm)
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{
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return sm->commit(sm);
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}
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static inline int dm_sm_inc_block(struct dm_space_map *sm, dm_block_t b)
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{
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return sm->inc_block(sm, b);
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}
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static inline int dm_sm_dec_block(struct dm_space_map *sm, dm_block_t b)
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{
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return sm->dec_block(sm, b);
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}
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static inline int dm_sm_new_block(struct dm_space_map *sm, dm_block_t *b)
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{
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return sm->new_block(sm, b);
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}
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static inline int dm_sm_root_size(struct dm_space_map *sm, size_t *result)
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{
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return sm->root_size(sm, result);
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}
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static inline int dm_sm_copy_root(struct dm_space_map *sm, void *copy_to_here_le, size_t len)
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{
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return sm->copy_root(sm, copy_to_here_le, len);
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}
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static inline int dm_sm_register_threshold_callback(struct dm_space_map *sm,
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dm_block_t threshold,
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dm_sm_threshold_fn fn,
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void *context)
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{
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if (sm->register_threshold_callback)
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return sm->register_threshold_callback(sm, threshold, fn, context);
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return -EINVAL;
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}
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#endif /* _LINUX_DM_SPACE_MAP_H */
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