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dm cache: add fail io mode and needs_check flag

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If a cache metadata operation fails (e.g. transaction commit) the
cache's metadata device will abort the current transaction, set a new
needs_check flag, and the cache will transition to "read-only" mode.  If
aborting the transaction or setting the needs_check flag fails the cache
will transition to "fail-io" mode.

Once needs_check is set the cache device will not be allowed to
activate.  Activation requires write access to metadata.  Future work is
needed to add proper support for running the cache in read-only mode.

Once in fail-io mode the cache will report a status of "Fail".

Also, add commit() wrapper that will disallow commits if in read_only or
fail mode.

Signed-off-by: Joe Thornber <ejt@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
This commit is contained in:
Joe Thornber
2015-04-22 16:42:35 -04:00
committed by Mike Snitzer
parent 88bf5184fa
commit 028ae9f76f
7 changed files with 320 additions and 58 deletions
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10
drivers/md/dm-cache-metadata.h
View File

@@ -102,6 +102,10 @@ struct dm_cache_statistics {
void dm_cache_metadata_get_stats(struct dm_cache_metadata *cmd,
struct dm_cache_statistics *stats);
/*
* 'void' because it's no big deal if it fails.
*/
void dm_cache_metadata_set_stats(struct dm_cache_metadata *cmd,
struct dm_cache_statistics *stats);
@@ -133,6 +137,12 @@ int dm_cache_write_hints(struct dm_cache_metadata *cmd, struct dm_cache_policy *
*/
int dm_cache_metadata_all_clean(struct dm_cache_metadata *cmd, bool *result);
bool dm_cache_metadata_needs_check(struct dm_cache_metadata *cmd);
int dm_cache_metadata_set_needs_check(struct dm_cache_metadata *cmd);
void dm_cache_metadata_set_read_only(struct dm_cache_metadata *cmd);
void dm_cache_metadata_set_read_write(struct dm_cache_metadata *cmd);
int dm_cache_metadata_abort(struct dm_cache_metadata *cmd);
/*----------------------------------------------------------------*/
#endif /* DM_CACHE_METADATA_H */