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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-policy-internal.h
View File

@@ -89,13 +89,15 @@ static inline void policy_tick(struct dm_cache_policy *p)
return p->tick(p);
}
static inline int policy_emit_config_values(struct dm_cache_policy *p, char *result, unsigned maxlen)
static inline int policy_emit_config_values(struct dm_cache_policy *p, char *result,
unsigned maxlen, ssize_t *sz_ptr)
{
ssize_t sz = 0;
ssize_t sz = *sz_ptr;
if (p->emit_config_values)
return p->emit_config_values(p, result, maxlen);
return p->emit_config_values(p, result, maxlen, sz_ptr);
DMEMIT("0");
DMEMIT("0 ");
*sz_ptr = sz;
return 0;
}