Rip out crappy 'read_metadata' function from the exception
store API. It is no longer needed, since the exception stores
are now responsible for caching exceptions.
RFC-by: Jonathan Brassow <jbrassow@xxxxxxxxxx>
Index: linux-2.6/drivers/md/dm-exception-store.h
===================================================================
--- linux-2.6.orig/drivers/md/dm-exception-store.h
+++ linux-2.6/drivers/md/dm-exception-store.h
@@ -34,16 +34,6 @@ struct dm_exception_store_type {
int (*resume) (struct dm_exception_store *store);
/*
- * The target shouldn't read the COW device until this is
- * called. As exceptions are read from the COW, they are
- * reported back via the callback.
- */
- int (*read_metadata) (struct dm_exception_store *store,
- int (*callback)(void *callback_context,
- chunk_t old, chunk_t new),
- void *callback_context);
-
- /*
* Find somewhere to store the next exception.
*/
int (*prepare_exception) (struct dm_exception_store *store,
Index: linux-2.6/drivers/md/dm-snap-persistent.c
===================================================================
--- linux-2.6.orig/drivers/md/dm-snap-persistent.c
+++ linux-2.6/drivers/md/dm-snap-persistent.c
@@ -413,15 +413,11 @@ static void write_exception(struct pstor
* 'full' is filled in to indicate if the area has been
* filled.
*/
-static int insert_exceptions(struct pstore *ps,
- int (*callback)(void *callback_context,
- chunk_t old, chunk_t new),
- void *callback_context,
- int *full)
+static int insert_exceptions(struct pstore *ps, int *full, int first_read)
{
- int r;
unsigned int i;
struct disk_exception de;
+ struct dm_exception *new;
/* presume the area is full */
*full = 1;
@@ -447,21 +443,30 @@ static int insert_exceptions(struct psto
if (ps->next_free <= de.new_chunk)
ps->next_free = de.new_chunk + 1;
+
/*
- * Otherwise we add the exception to the snapshot.
+ * If this is not our first time reading the
+ * metadata, let's avoid adding duplicates to
+ * to our cache.
*/
- r = callback(callback_context, de.old_chunk, de.new_chunk);
- if (r)
- return r;
+ if (!first_read &&
+ dm_lookup_exception(ps->table, de.old_chunk))
+ continue;
+
+ new = dm_alloc_exception(ps->table);
+ if (!new)
+ return -ENOMEM;
+
+ new->old_chunk = de.old_chunk;
+ new->new_chunk = de.new_chunk;
+
+ dm_insert_exception(ps->table, new);
}
return 0;
}
-static int read_exceptions(struct pstore *ps,
- int (*callback)(void *callback_context, chunk_t old,
- chunk_t new),
- void *callback_context)
+static int read_exceptions(struct pstore *ps, int first_read)
{
int r, full = 1;
@@ -474,7 +479,7 @@ static int read_exceptions(struct pstore
if (r)
return r;
- r = insert_exceptions(ps, callback, callback_context, &full);
+ r = insert_exceptions(ps, &full, first_read);
if (r)
return r;
}
@@ -508,20 +513,24 @@ static void persistent_dtr(struct dm_exc
kfree(ps);
}
-static int persistent_read_metadata(struct dm_exception_store *store,
- int (*callback)(void *callback_context,
- chunk_t old, chunk_t new),
- void *callback_context)
+/*
+ * persistent_resume
+ * @store
+ *
+ * Read metadata of the disk and store in our exception table cache.
+ *
+ * Returns: 0 on success, -Exxx on error
+ */
+static int persistent_resume(struct dm_exception_store *store)
{
+ int first_read = 1;
int r, uninitialized_var(new_snapshot);
struct pstore *ps = get_info(store);
- if (ps->callbacks)
- /*
- * Temporary work around for having two different functions
- * that get us going... 'read_metadata' and 'resume'.
- */
+ if (ps->callbacks) {
+ first_read = 0;
goto read_metadata;
+ }
/*
* Read the snapshot header.
@@ -576,43 +585,11 @@ static int persistent_read_metadata(stru
* Read the metadata.
*/
read_metadata:
- r = read_exceptions(ps, callback, callback_context);
+ r = read_exceptions(ps, first_read);
return r;
}
-/* This function is temporary for patch cleanliness */
-static int add_exception(void *context, chunk_t old, chunk_t new)
-{
- struct dm_exception_store *store = context;
- struct pstore *ps = get_info(store);
- struct dm_exception *e;
-
- e = dm_alloc_exception(ps->table);
- if (!e)
- return -ENOMEM;
-
- e->old_chunk = old;
- e->new_chunk = new;
-
- dm_insert_exception(ps->table, e);
-
- return 0;
-}
-
-/*
- * persistent_resume
- * @store
- *
- * Read metadata of the disk and store in our exception table cache.
- *
- * Returns: 0 on success, -Exxx on error
- */
-static int persistent_resume(struct dm_exception_store *store)
-{
- return persistent_read_metadata(store, add_exception, store);
-}
-
static int persistent_prepare_exception(struct dm_exception_store *store,
struct dm_exception *e)
{
@@ -648,6 +625,7 @@ static void persistent_commit_exception(
unsigned int i;
struct pstore *ps = get_info(store);
struct disk_exception de;
+ struct dm_exception *new;
struct commit_callback *cb;
de.old_chunk = e->old_chunk;
@@ -660,7 +638,13 @@ static void persistent_commit_exception(
* to put it in the cache though, the callbacks will have to
* report the failure.
*/
- if (add_exception(store, de.old_chunk, de.new_chunk))
+ new = dm_alloc_exception(ps->table);
+ if (new) {
+ new->old_chunk = de.old_chunk;
+ new->new_chunk = de.new_chunk;
+
+ dm_insert_exception(ps->table, new);
+ } else
ps->valid = 0;
/*
@@ -811,7 +795,6 @@ static struct dm_exception_store_type _p
.ctr = persistent_ctr,
.dtr = persistent_dtr,
.resume = persistent_resume,
- .read_metadata = persistent_read_metadata,
.prepare_exception = persistent_prepare_exception,
.commit_exception = persistent_commit_exception,
.lookup_exception = persistent_lookup_exception,
@@ -826,7 +809,6 @@ static struct dm_exception_store_type _p
.ctr = persistent_ctr,
.dtr = persistent_dtr,
.resume = persistent_resume,
- .read_metadata = persistent_read_metadata,
.prepare_exception = persistent_prepare_exception,
.commit_exception = persistent_commit_exception,
.lookup_exception = persistent_lookup_exception,
Index: linux-2.6/drivers/md/dm-snap-transient.c
===================================================================
--- linux-2.6.orig/drivers/md/dm-snap-transient.c
+++ linux-2.6/drivers/md/dm-snap-transient.c
@@ -44,14 +44,6 @@ static void transient_dtr(struct dm_exce
kfree(tc);
}
-static int transient_read_metadata(struct dm_exception_store *store,
- int (*callback)(void *callback_context,
- chunk_t old, chunk_t new),
- void *callback_context)
-{
- return 0;
-}
-
static int transient_resume(struct dm_exception_store *store)
{
return 0;
@@ -173,7 +165,6 @@ static struct dm_exception_store_type _t
.ctr = transient_ctr,
.dtr = transient_dtr,
.resume = transient_resume,
- .read_metadata = transient_read_metadata,
.prepare_exception = transient_prepare_exception,
.commit_exception = transient_commit_exception,
.lookup_exception = transient_lookup_exception,
@@ -187,7 +178,6 @@ static struct dm_exception_store_type _t
.ctr = transient_ctr,
.dtr = transient_dtr,
.resume = transient_resume,
- .read_metadata = transient_read_metadata,
.prepare_exception = transient_prepare_exception,
.commit_exception = transient_commit_exception,
.lookup_exception = transient_lookup_exception,
--
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