*/
#include "dm-exception-store.h"
-#include "dm-snap.h"
#include <linux/mm.h>
#include <linux/pagemap.h>
*/
#define SNAPSHOT_DISK_VERSION 1
+#define NUM_SNAPSHOT_HDR_CHUNKS 1
+
struct disk_header {
uint32_t magic;
* The top level structure for a persistent exception store.
*/
struct pstore {
- struct dm_snapshot *snap; /* up pointer to my snapshot */
+ struct dm_exception_store *store;
int version;
int valid;
uint32_t exceptions_per_area;
void *zero_area;
/*
+ * An area used for header. The header can be written
+ * concurrently with metadata (when invalidating the snapshot),
+ * so it needs a separate buffer.
+ */
+ void *header_area;
+
+ /*
* Used to keep track of which metadata area the data in
* 'chunk' refers to.
*/
/*
* 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 r = -ENOMEM;
size_t len;
- len = ps->snap->chunk_size << SECTOR_SHIFT;
+ len = ps->store->chunk_size << SECTOR_SHIFT;
/*
* Allocate the chunk_size block of memory that will hold
*/
ps->area = vmalloc(len);
if (!ps->area)
- return r;
+ goto err_area;
ps->zero_area = vmalloc(len);
- if (!ps->zero_area) {
- vfree(ps->area);
- return r;
- }
+ if (!ps->zero_area)
+ goto err_zero_area;
memset(ps->zero_area, 0, len);
+ ps->header_area = vmalloc(len);
+ if (!ps->header_area)
+ goto err_header_area;
+
return 0;
+
+err_header_area:
+ vfree(ps->zero_area);
+
+err_zero_area:
+ vfree(ps->area);
+
+err_area:
+ return r;
}
static void free_area(struct pstore *ps)
{
- vfree(ps->area);
+ if (ps->area)
+ vfree(ps->area);
ps->area = NULL;
- vfree(ps->zero_area);
+
+ if (ps->zero_area)
+ vfree(ps->zero_area);
ps->zero_area = NULL;
+
+ if (ps->header_area)
+ vfree(ps->header_area);
+ ps->header_area = NULL;
}
struct mdata_req {
/*
* Read or write a chunk aligned and sized block of data from a device.
*/
-static int chunk_io(struct pstore *ps, chunk_t chunk, int rw, int metadata)
+static int chunk_io(struct pstore *ps, void *area, chunk_t chunk, int rw,
+ int metadata)
{
struct dm_io_region where = {
- .bdev = ps->snap->cow->bdev,
- .sector = ps->snap->chunk_size * chunk,
- .count = ps->snap->chunk_size,
+ .bdev = dm_snap_cow(ps->store->snap)->bdev,
+ .sector = ps->store->chunk_size * chunk,
+ .count = ps->store->chunk_size,
};
struct dm_io_request io_req = {
.bi_rw = rw,
.mem.type = DM_IO_VMA,
- .mem.ptr.vma = ps->area,
+ .mem.ptr.vma = area,
.client = ps->io_client,
.notify.fn = NULL,
};
* Issue the synchronous I/O from a different thread
* to avoid generic_make_request recursion.
*/
- INIT_WORK(&req.work, do_metadata);
+ INIT_WORK_ON_STACK(&req.work, do_metadata);
queue_work(ps->metadata_wq, &req.work);
flush_workqueue(ps->metadata_wq);
chunk = area_location(ps, ps->current_area);
- r = chunk_io(ps, chunk, rw, 0);
+ r = chunk_io(ps, ps->area, chunk, rw, 0);
if (r)
return r;
static void zero_memory_area(struct pstore *ps)
{
- memset(ps->area, 0, ps->snap->chunk_size << SECTOR_SHIFT);
+ memset(ps->area, 0, ps->store->chunk_size << SECTOR_SHIFT);
}
static int zero_disk_area(struct pstore *ps, chunk_t area)
{
- struct dm_io_region where = {
- .bdev = ps->snap->cow->bdev,
- .sector = ps->snap->chunk_size * area_location(ps, area),
- .count = ps->snap->chunk_size,
- };
- struct dm_io_request io_req = {
- .bi_rw = WRITE,
- .mem.type = DM_IO_VMA,
- .mem.ptr.vma = ps->zero_area,
- .client = ps->io_client,
- .notify.fn = NULL,
- };
-
- return dm_io(&io_req, 1, &where, NULL);
+ return chunk_io(ps, ps->zero_area, area_location(ps, area), WRITE, 0);
}
static int read_header(struct pstore *ps, int *new_snapshot)
{
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->snap->chunk_size) {
- ps->snap->chunk_size = max(DM_CHUNK_SIZE_DEFAULT_SECTORS,
- bdev_hardsect_size(ps->snap->cow->bdev) >> 9);
- ps->snap->chunk_mask = ps->snap->chunk_size - 1;
- ps->snap->chunk_shift = ffs(ps->snap->chunk_size) - 1;
+ if (!ps->store->chunk_size) {
+ ps->store->chunk_size = max(DM_CHUNK_SIZE_DEFAULT_SECTORS,
+ 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;
}
- ps->io_client = dm_io_client_create(sectors_to_pages(ps->snap->
+ ps->io_client = dm_io_client_create(sectors_to_pages(ps->store->
chunk_size));
if (IS_ERR(ps->io_client))
return PTR_ERR(ps->io_client);
if (r)
return r;
- r = chunk_io(ps, 0, READ, 1);
+ r = chunk_io(ps, ps->header_area, 0, READ, 1);
if (r)
goto bad;
- dh = (struct disk_header *) ps->area;
+ dh = ps->header_area;
if (le32_to_cpu(dh->magic) == 0) {
*new_snapshot = 1;
ps->version = le32_to_cpu(dh->version);
chunk_size = le32_to_cpu(dh->chunk_size);
- if (!chunk_size_supplied || ps->snap->chunk_size == chunk_size)
+ if (ps->store->chunk_size == chunk_size)
return 0;
- DMWARN("chunk size %llu in device metadata overrides "
- "table chunk size of %llu.",
- (unsigned long long)chunk_size,
- (unsigned long long)ps->snap->chunk_size);
+ if (chunk_size_supplied)
+ 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);
- ps->snap->chunk_size = chunk_size;
- ps->snap->chunk_mask = chunk_size - 1;
- ps->snap->chunk_shift = ffs(chunk_size) - 1;
+ r = dm_exception_store_set_chunk_size(ps->store, chunk_size,
+ &chunk_err);
+ if (r) {
+ DMERR("invalid on-disk chunk size %u: %s.",
+ chunk_size, chunk_err);
+ return r;
+ }
- r = dm_io_client_resize(sectors_to_pages(ps->snap->chunk_size),
+ r = dm_io_client_resize(sectors_to_pages(ps->store->chunk_size),
ps->io_client);
if (r)
return r;
{
struct disk_header *dh;
- memset(ps->area, 0, ps->snap->chunk_size << SECTOR_SHIFT);
+ memset(ps->header_area, 0, ps->store->chunk_size << SECTOR_SHIFT);
- dh = (struct disk_header *) ps->area;
+ dh = ps->header_area;
dh->magic = cpu_to_le32(SNAP_MAGIC);
dh->valid = cpu_to_le32(ps->valid);
dh->version = cpu_to_le32(ps->version);
- dh->chunk_size = cpu_to_le32(ps->snap->chunk_size);
+ dh->chunk_size = cpu_to_le32(ps->store->chunk_size);
- return chunk_io(ps, 0, WRITE, 1);
+ return chunk_io(ps, ps->header_area, 0, WRITE, 1);
}
/*
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->snap->chunk_size;
- *denominator = get_dev_size(store->snap->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_destroy(struct dm_exception_store *store)
+static void persistent_dtr(struct dm_exception_store *store)
{
struct pstore *ps = get_info(store);
destroy_workqueue(ps->metadata_wq);
- dm_io_client_destroy(ps->io_client);
- vfree(ps->callbacks);
+
+ /* Created in read_header */
+ if (ps->io_client)
+ dm_io_client_destroy(ps->io_client);
free_area(ps);
+
+ /* Allocated in persistent_read_metadata */
+ if (ps->callbacks)
+ vfree(ps->callbacks);
+
kfree(ps);
}
/*
* Now we know correct chunk_size, complete the initialisation.
*/
- ps->exceptions_per_area = (ps->snap->chunk_size << SECTOR_SHIFT) /
+ ps->exceptions_per_area = (ps->store->chunk_size << SECTOR_SHIFT) /
sizeof(struct disk_exception);
ps->callbacks = dm_vcalloc(ps->exceptions_per_area,
sizeof(*ps->callbacks));
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->snap->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->snap->chunk_size))
+ if (size < ((ps->next_free + 1) * store->chunk_size))
return -ENOSPC;
e->new_chunk = ps->next_free;
}
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)
{
/*
* Commit exceptions to disk.
*/
- if (ps->valid && area_io(ps, WRITE))
+ if (ps->valid && area_io(ps, WRITE_BARRIER))
ps->valid = 0;
/*
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);
DMWARN("write header failed");
}
-int dm_create_persistent(struct dm_exception_store *store)
+static int persistent_ctr(struct dm_exception_store *store,
+ unsigned argc, char **argv)
{
struct pstore *ps;
/* allocate the pstore */
- ps = kmalloc(sizeof(*ps), GFP_KERNEL);
+ ps = kzalloc(sizeof(*ps), GFP_KERNEL);
if (!ps)
return -ENOMEM;
- ps->snap = store->snap;
+ ps->store = store;
ps->valid = 1;
ps->version = SNAPSHOT_DISK_VERSION;
ps->area = NULL;
- ps->next_free = 2; /* skipping the header and first area */
+ ps->zero_area = NULL;
+ ps->header_area = NULL;
+ ps->next_free = NUM_SNAPSHOT_HDR_CHUNKS + 1; /* header and 1st area */
ps->current_committed = 0;
ps->callback_count = 0;
return -ENOMEM;
}
- store->destroy = persistent_destroy;
- store->read_metadata = persistent_read_metadata;
- store->prepare_exception = persistent_prepare_exception;
- store->commit_exception = persistent_commit_exception;
- store->drop_snapshot = persistent_drop_snapshot;
- store->fraction_full = persistent_fraction_full;
store->context = ps;
return 0;
}
+static unsigned persistent_status(struct dm_exception_store *store,
+ status_type_t status, char *result,
+ unsigned maxlen)
+{
+ unsigned sz = 0;
+
+ switch (status) {
+ case STATUSTYPE_INFO:
+ break;
+ case STATUSTYPE_TABLE:
+ DMEMIT(" P %llu", (unsigned long long)store->chunk_size);
+ }
+
+ return sz;
+}
+
+static struct dm_exception_store_type _persistent_type = {
+ .name = "persistent",
+ .module = THIS_MODULE,
+ .ctr = persistent_ctr,
+ .dtr = persistent_dtr,
+ .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,
+ .usage = persistent_usage,
+ .status = persistent_status,
+};
+
+static struct dm_exception_store_type _persistent_compat_type = {
+ .name = "P",
+ .module = THIS_MODULE,
+ .ctr = persistent_ctr,
+ .dtr = persistent_dtr,
+ .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,
+ .usage = persistent_usage,
+ .status = persistent_status,
+};
+
int dm_persistent_snapshot_init(void)
{
- return 0;
+ int r;
+
+ r = dm_exception_store_type_register(&_persistent_type);
+ if (r) {
+ DMERR("Unable to register persistent exception store type");
+ return r;
+ }
+
+ r = dm_exception_store_type_register(&_persistent_compat_type);
+ if (r) {
+ DMERR("Unable to register old-style persistent exception "
+ "store type");
+ dm_exception_store_type_unregister(&_persistent_type);
+ return r;
+ }
+
+ return r;
}
void dm_persistent_snapshot_exit(void)
{
+ dm_exception_store_type_unregister(&_persistent_type);
+ dm_exception_store_type_unregister(&_persistent_compat_type);
}
git://ftp.safe.ca / safe / jmp / linux-2.6 / blobdiff