*/
#define SNAPSHOT_DISK_VERSION 1
+#define NUM_SNAPSHOT_HDR_CHUNKS 1
+
struct disk_header {
uint32_t magic;
/*
* The next free chunk for an exception.
+ *
+ * When creating exceptions, all the chunks here and above are
+ * free. It holds the next chunk to be allocated. On rare
+ * occasions (e.g. after a system crash) holes can be left in
+ * the exception store because chunks can be committed out of
+ * order.
+ *
+ * When merging exceptions, it does not necessarily mean all the
+ * chunks here and above are free. It holds the value it would
+ * have held if all chunks had been committed in order of
+ * allocation. Consequently the value may occasionally be
+ * slightly too low, but since it's only used for 'status' and
+ * it can never reach its minimum value too early this doesn't
+ * matter.
*/
+
chunk_t next_free;
/*
int metadata)
{
struct dm_io_region where = {
- .bdev = ps->store->cow->bdev,
+ .bdev = dm_snap_cow(ps->store->snap)->bdev,
.sector = ps->store->chunk_size * chunk,
.count = ps->store->chunk_size,
};
{
int r;
struct disk_header *dh;
- chunk_t chunk_size;
+ unsigned chunk_size;
int chunk_size_supplied = 1;
char *chunk_err;
/*
- * Use default chunk size (or hardsect_size, if larger) if none supplied
+ * Use default chunk size (or logical_block_size, if larger)
+ * if none supplied
*/
if (!ps->store->chunk_size) {
ps->store->chunk_size = max(DM_CHUNK_SIZE_DEFAULT_SECTORS,
- bdev_logical_block_size(ps->store->cow->bdev) >> 9);
+ bdev_logical_block_size(dm_snap_cow(ps->store->snap)->
+ bdev) >> 9);
ps->store->chunk_mask = ps->store->chunk_size - 1;
ps->store->chunk_shift = ffs(ps->store->chunk_size) - 1;
chunk_size_supplied = 0;
return 0;
if (chunk_size_supplied)
- DMWARN("chunk size %llu in device metadata overrides "
- "table chunk size of %llu.",
- (unsigned long long)chunk_size,
- (unsigned long long)ps->store->chunk_size);
+ DMWARN("chunk size %u in device metadata overrides "
+ "table chunk size of %u.",
+ chunk_size, ps->store->chunk_size);
/* We had a bogus chunk_size. Fix stuff up. */
free_area(ps);
r = dm_exception_store_set_chunk_size(ps->store, chunk_size,
&chunk_err);
if (r) {
- DMERR("invalid on-disk chunk size %llu: %s.",
- (unsigned long long)chunk_size, chunk_err);
+ DMERR("invalid on-disk chunk size %u: %s.",
+ chunk_size, chunk_err);
return r;
}
e->new_chunk = cpu_to_le64(de->new_chunk);
}
+static void clear_exception(struct pstore *ps, uint32_t index)
+{
+ struct disk_exception *e = get_exception(ps, index);
+
+ /* clear it */
+ e->old_chunk = 0;
+ e->new_chunk = 0;
+}
+
/*
* Registers the exceptions that are present in the current area.
* 'full' is filled in to indicate if the area has been
return (struct pstore *) store->context;
}
-static void persistent_fraction_full(struct dm_exception_store *store,
- sector_t *numerator, sector_t *denominator)
+static void persistent_usage(struct dm_exception_store *store,
+ sector_t *total_sectors,
+ sector_t *sectors_allocated,
+ sector_t *metadata_sectors)
{
- *numerator = get_info(store)->next_free * store->chunk_size;
- *denominator = get_dev_size(store->cow->bdev);
+ struct pstore *ps = get_info(store);
+
+ *sectors_allocated = ps->next_free * store->chunk_size;
+ *total_sectors = get_dev_size(dm_snap_cow(store->snap)->bdev);
+
+ /*
+ * First chunk is the fixed header.
+ * Then there are (ps->current_area + 1) metadata chunks, each one
+ * separated from the next by ps->exceptions_per_area data chunks.
+ */
+ *metadata_sectors = (ps->current_area + 1 + NUM_SNAPSHOT_HDR_CHUNKS) *
+ store->chunk_size;
}
static void persistent_dtr(struct dm_exception_store *store)
ps->current_area = 0;
zero_memory_area(ps);
r = zero_disk_area(ps, 0);
- if (r) {
+ if (r)
DMWARN("zero_disk_area(0) failed");
- return r;
- }
- } else {
- /*
- * Sanity checks.
- */
- if (ps->version != SNAPSHOT_DISK_VERSION) {
- DMWARN("unable to handle snapshot disk version %d",
- ps->version);
- return -EINVAL;
- }
+ return r;
+ }
+ /*
+ * Sanity checks.
+ */
+ if (ps->version != SNAPSHOT_DISK_VERSION) {
+ DMWARN("unable to handle snapshot disk version %d",
+ ps->version);
+ return -EINVAL;
+ }
- /*
- * Metadata are valid, but snapshot is invalidated
- */
- if (!ps->valid)
- return 1;
+ /*
+ * Metadata are valid, but snapshot is invalidated
+ */
+ if (!ps->valid)
+ return 1;
- /*
- * Read the metadata.
- */
- r = read_exceptions(ps, callback, callback_context);
- if (r)
- return r;
- }
+ /*
+ * Read the metadata.
+ */
+ r = read_exceptions(ps, callback, callback_context);
- return 0;
+ return r;
}
static int persistent_prepare_exception(struct dm_exception_store *store,
- struct dm_snap_exception *e)
+ struct dm_exception *e)
{
struct pstore *ps = get_info(store);
uint32_t stride;
chunk_t next_free;
- sector_t size = get_dev_size(store->cow->bdev);
+ sector_t size = get_dev_size(dm_snap_cow(store->snap)->bdev);
/* Is there enough room ? */
if (size < ((ps->next_free + 1) * store->chunk_size))
}
static void persistent_commit_exception(struct dm_exception_store *store,
- struct dm_snap_exception *e,
+ struct dm_exception *e,
void (*callback) (void *, int success),
void *callback_context)
{
ps->callback_count = 0;
}
+static int persistent_prepare_merge(struct dm_exception_store *store,
+ chunk_t *last_old_chunk,
+ chunk_t *last_new_chunk)
+{
+ struct pstore *ps = get_info(store);
+ struct disk_exception de;
+ int nr_consecutive;
+ int r;
+
+ /*
+ * When current area is empty, move back to preceding area.
+ */
+ if (!ps->current_committed) {
+ /*
+ * Have we finished?
+ */
+ if (!ps->current_area)
+ return 0;
+
+ ps->current_area--;
+ r = area_io(ps, READ);
+ if (r < 0)
+ return r;
+ ps->current_committed = ps->exceptions_per_area;
+ }
+
+ read_exception(ps, ps->current_committed - 1, &de);
+ *last_old_chunk = de.old_chunk;
+ *last_new_chunk = de.new_chunk;
+
+ /*
+ * Find number of consecutive chunks within the current area,
+ * working backwards.
+ */
+ for (nr_consecutive = 1; nr_consecutive < ps->current_committed;
+ nr_consecutive++) {
+ read_exception(ps, ps->current_committed - 1 - nr_consecutive,
+ &de);
+ if (de.old_chunk != *last_old_chunk - nr_consecutive ||
+ de.new_chunk != *last_new_chunk - nr_consecutive)
+ break;
+ }
+
+ return nr_consecutive;
+}
+
+static int persistent_commit_merge(struct dm_exception_store *store,
+ int nr_merged)
+{
+ int r, i;
+ struct pstore *ps = get_info(store);
+
+ BUG_ON(nr_merged > ps->current_committed);
+
+ for (i = 0; i < nr_merged; i++)
+ clear_exception(ps, ps->current_committed - 1 - i);
+
+ r = area_io(ps, WRITE);
+ if (r < 0)
+ return r;
+
+ ps->current_committed -= nr_merged;
+
+ /*
+ * At this stage, only persistent_usage() uses ps->next_free, so
+ * we make no attempt to keep ps->next_free strictly accurate
+ * as exceptions may have been committed out-of-order originally.
+ * Once a snapshot has become merging, we set it to the value it
+ * would have held had all the exceptions been committed in order.
+ *
+ * ps->current_area does not get reduced by prepare_merge() until
+ * after commit_merge() has removed the nr_merged previous exceptions.
+ */
+ ps->next_free = (area_location(ps, ps->current_area) - 1) +
+ (ps->current_committed + 1) + NUM_SNAPSHOT_HDR_CHUNKS;
+
+ return 0;
+}
+
static void persistent_drop_snapshot(struct dm_exception_store *store)
{
struct pstore *ps = get_info(store);
ps->area = NULL;
ps->zero_area = NULL;
ps->header_area = NULL;
- ps->next_free = 2; /* skipping the header and first area */
+ ps->next_free = NUM_SNAPSHOT_HDR_CHUNKS + 1; /* header and 1st area */
ps->current_committed = 0;
ps->callback_count = 0;
case STATUSTYPE_INFO:
break;
case STATUSTYPE_TABLE:
- DMEMIT(" %s P %llu", store->cow->name,
- (unsigned long long)store->chunk_size);
+ DMEMIT(" P %llu", (unsigned long long)store->chunk_size);
}
return sz;
.read_metadata = persistent_read_metadata,
.prepare_exception = persistent_prepare_exception,
.commit_exception = persistent_commit_exception,
+ .prepare_merge = persistent_prepare_merge,
+ .commit_merge = persistent_commit_merge,
.drop_snapshot = persistent_drop_snapshot,
- .fraction_full = persistent_fraction_full,
+ .usage = persistent_usage,
.status = persistent_status,
};
.read_metadata = persistent_read_metadata,
.prepare_exception = persistent_prepare_exception,
.commit_exception = persistent_commit_exception,
+ .prepare_merge = persistent_prepare_merge,
+ .commit_merge = persistent_commit_merge,
.drop_snapshot = persistent_drop_snapshot,
- .fraction_full = persistent_fraction_full,
+ .usage = persistent_usage,
.status = persistent_status,
};
git://ftp.safe.ca / safe / jmp / linux-2.6 / blobdiff