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Introduce flapping of metadata config sections

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This feature provides double buffering of config sections to prevent
situation when power failure during metadata flush leads to partially
updated metadata. Flapping mechanism makes it always possible to perform
graceful rollback to previous config metadata content in such situation.

Signed-off-by: Robert Baldyga <robert.baldyga@intel.com>
This commit is contained in:
Robert Baldyga
2021-12-09 23:03:32 +01:00
parent 60218759d2
commit 99c8c05f3f
10 changed files with 172 additions and 53 deletions
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36
src/metadata/metadata.c
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@@ -187,6 +187,34 @@ static int64_t ocf_metadata_get_element_size(
return size;
}
/*
* Check if particular metadata type supports flapping
*/
static bool ocf_metadata_is_flapped(
enum ocf_metadata_segment_id type)
{
switch (type) {
case metadata_segment_part_config:
case metadata_segment_core_config:
case metadata_segment_core_uuid:
return true;
case metadata_segment_sb_config:
case metadata_segment_sb_runtime:
case metadata_segment_reserved:
case metadata_segment_part_runtime:
case metadata_segment_core_runtime:
case metadata_segment_cleaning:
case metadata_segment_lru:
case metadata_segment_collision:
case metadata_segment_list_info:
case metadata_segment_hash:
default:
return false;
}
}
/*
* Metadata calculation exception handling.
*
@@ -484,6 +512,9 @@ static struct ocf_metadata_ctrl *ocf_metadata_ctrl_init(
= ocf_metadata_get_element_size(i, 0);
raw->entries_in_page = PAGE_SIZE / raw->entry_size;
/* Setup flapping support */
raw->flapping = ocf_metadata_is_flapped(i);
/* Setup number of entries */
raw->entries = ocf_metadata_get_entries(i, 0);
@@ -675,6 +706,9 @@ int ocf_metadata_init_variable_size(struct ocf_cache *cache,
raw->entry_size
= ocf_metadata_get_element_size(i, line_size);
raw->entries_in_page = PAGE_SIZE / raw->entry_size;
/* Setup flapping support */
raw->flapping = ocf_metadata_is_flapped(i);
}
if (0 != ocf_metadata_calculate_metadata_size(cache, ctrl, line_size)) {
@@ -1009,7 +1043,7 @@ void ocf_metadata_flush_collision(ocf_cache_t cache,
ctrl = cache->metadata.priv;
raw = &ctrl->raw_desc[metadata_segment_collision];
ocf_metadata_raw_flush_all(cache, raw, cmpl, priv);
ocf_metadata_raw_flush_all(cache, raw, cmpl, priv, 0);
}
/*