mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-08-23 09:19:51 +00:00
![Joe Thornber](/assets/img/avatar_default.png)
The disk space map stores it's index entries in a btree, these are accessed very frequently, so having a few cached makes a big difference to performance. With this change provisioning a new block takes roughly 20% less cpu. Signed-off-by: Joe Thornber <ejt@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
145 lines
4.1 KiB
C
145 lines
4.1 KiB
C
/*
|
|
* Copyright (C) 2011 Red Hat, Inc.
|
|
*
|
|
* This file is released under the GPL.
|
|
*/
|
|
|
|
#ifndef DM_SPACE_MAP_COMMON_H
|
|
#define DM_SPACE_MAP_COMMON_H
|
|
|
|
#include "dm-btree.h"
|
|
|
|
/*----------------------------------------------------------------*/
|
|
|
|
/*
|
|
* Low level disk format
|
|
*
|
|
* Bitmap btree
|
|
* ------------
|
|
*
|
|
* Each value stored in the btree is an index_entry. This points to a
|
|
* block that is used as a bitmap. Within the bitmap hold 2 bits per
|
|
* entry, which represent UNUSED = 0, REF_COUNT = 1, REF_COUNT = 2 and
|
|
* REF_COUNT = many.
|
|
*
|
|
* Refcount btree
|
|
* --------------
|
|
*
|
|
* Any entry that has a ref count higher than 2 gets entered in the ref
|
|
* count tree. The leaf values for this tree is the 32-bit ref count.
|
|
*/
|
|
|
|
struct disk_index_entry {
|
|
__le64 blocknr;
|
|
__le32 nr_free;
|
|
__le32 none_free_before;
|
|
} __attribute__ ((packed, aligned(8)));
|
|
|
|
|
|
#define MAX_METADATA_BITMAPS 255
|
|
struct disk_metadata_index {
|
|
__le32 csum;
|
|
__le32 padding;
|
|
__le64 blocknr;
|
|
|
|
struct disk_index_entry index[MAX_METADATA_BITMAPS];
|
|
} __attribute__ ((packed, aligned(8)));
|
|
|
|
struct ll_disk;
|
|
|
|
typedef int (*load_ie_fn)(struct ll_disk *ll, dm_block_t index, struct disk_index_entry *result);
|
|
typedef int (*save_ie_fn)(struct ll_disk *ll, dm_block_t index, struct disk_index_entry *ie);
|
|
typedef int (*init_index_fn)(struct ll_disk *ll);
|
|
typedef int (*open_index_fn)(struct ll_disk *ll);
|
|
typedef dm_block_t (*max_index_entries_fn)(struct ll_disk *ll);
|
|
typedef int (*commit_fn)(struct ll_disk *ll);
|
|
|
|
/*
|
|
* A lot of time can be wasted reading and writing the same
|
|
* index entry. So we cache a few entries.
|
|
*/
|
|
#define IE_CACHE_SIZE 64
|
|
#define IE_CACHE_MASK (IE_CACHE_SIZE - 1)
|
|
|
|
struct ie_cache {
|
|
bool valid;
|
|
bool dirty;
|
|
dm_block_t index;
|
|
struct disk_index_entry ie;
|
|
};
|
|
|
|
struct ll_disk {
|
|
struct dm_transaction_manager *tm;
|
|
struct dm_btree_info bitmap_info;
|
|
struct dm_btree_info ref_count_info;
|
|
|
|
uint32_t block_size;
|
|
uint32_t entries_per_block;
|
|
dm_block_t nr_blocks;
|
|
dm_block_t nr_allocated;
|
|
|
|
/*
|
|
* bitmap_root may be a btree root or a simple index.
|
|
*/
|
|
dm_block_t bitmap_root;
|
|
|
|
dm_block_t ref_count_root;
|
|
|
|
struct disk_metadata_index mi_le;
|
|
load_ie_fn load_ie;
|
|
save_ie_fn save_ie;
|
|
init_index_fn init_index;
|
|
open_index_fn open_index;
|
|
max_index_entries_fn max_entries;
|
|
commit_fn commit;
|
|
bool bitmap_index_changed:1;
|
|
|
|
struct ie_cache ie_cache[IE_CACHE_SIZE];
|
|
};
|
|
|
|
struct disk_sm_root {
|
|
__le64 nr_blocks;
|
|
__le64 nr_allocated;
|
|
__le64 bitmap_root;
|
|
__le64 ref_count_root;
|
|
} __attribute__ ((packed, aligned(8)));
|
|
|
|
#define ENTRIES_PER_BYTE 4
|
|
|
|
struct disk_bitmap_header {
|
|
__le32 csum;
|
|
__le32 not_used;
|
|
__le64 blocknr;
|
|
} __attribute__ ((packed, aligned(8)));
|
|
|
|
/*----------------------------------------------------------------*/
|
|
|
|
int sm_ll_extend(struct ll_disk *ll, dm_block_t extra_blocks);
|
|
int sm_ll_lookup_bitmap(struct ll_disk *ll, dm_block_t b, uint32_t *result);
|
|
int sm_ll_lookup(struct ll_disk *ll, dm_block_t b, uint32_t *result);
|
|
int sm_ll_find_free_block(struct ll_disk *ll, dm_block_t begin,
|
|
dm_block_t end, dm_block_t *result);
|
|
int sm_ll_find_common_free_block(struct ll_disk *old_ll, struct ll_disk *new_ll,
|
|
dm_block_t begin, dm_block_t end, dm_block_t *result);
|
|
|
|
/*
|
|
* The next three functions return (via nr_allocations) the net number of
|
|
* allocations that were made. This number may be negative if there were
|
|
* more frees than allocs.
|
|
*/
|
|
int sm_ll_insert(struct ll_disk *ll, dm_block_t b, uint32_t ref_count, int32_t *nr_allocations);
|
|
int sm_ll_inc(struct ll_disk *ll, dm_block_t b, dm_block_t e, int32_t *nr_allocations);
|
|
int sm_ll_dec(struct ll_disk *ll, dm_block_t b, dm_block_t e, int32_t *nr_allocations);
|
|
int sm_ll_commit(struct ll_disk *ll);
|
|
|
|
int sm_ll_new_metadata(struct ll_disk *ll, struct dm_transaction_manager *tm);
|
|
int sm_ll_open_metadata(struct ll_disk *ll, struct dm_transaction_manager *tm,
|
|
void *root_le, size_t len);
|
|
|
|
int sm_ll_new_disk(struct ll_disk *ll, struct dm_transaction_manager *tm);
|
|
int sm_ll_open_disk(struct ll_disk *ll, struct dm_transaction_manager *tm,
|
|
void *root_le, size_t len);
|
|
|
|
/*----------------------------------------------------------------*/
|
|
|
|
#endif /* DM_SPACE_MAP_COMMON_H */
|