| /* |
| * Copyright (C) 2001-2002 Sistina Software (UK) Limited. |
| * Copyright (C) 2006-2008 Red Hat GmbH |
| * |
| * This file is released under the GPL. |
| */ |
| |
| #include "dm-exception-store.h" |
| |
| #include <linux/mm.h> |
| #include <linux/pagemap.h> |
| #include <linux/vmalloc.h> |
| #include <linux/slab.h> |
| #include <linux/dm-io.h> |
| |
| #define DM_MSG_PREFIX "persistent snapshot" |
| #define DM_CHUNK_SIZE_DEFAULT_SECTORS 32 /* 16KB */ |
| |
| /*----------------------------------------------------------------- |
| * Persistent snapshots, by persistent we mean that the snapshot |
| * will survive a reboot. |
| *---------------------------------------------------------------*/ |
| |
| /* |
| * We need to store a record of which parts of the origin have |
| * been copied to the snapshot device. The snapshot code |
| * requires that we copy exception chunks to chunk aligned areas |
| * of the COW store. It makes sense therefore, to store the |
| * metadata in chunk size blocks. |
| * |
| * There is no backward or forward compatibility implemented, |
| * snapshots with different disk versions than the kernel will |
| * not be usable. It is expected that "lvcreate" will blank out |
| * the start of a fresh COW device before calling the snapshot |
| * constructor. |
| * |
| * The first chunk of the COW device just contains the header. |
| * After this there is a chunk filled with exception metadata, |
| * followed by as many exception chunks as can fit in the |
| * metadata areas. |
| * |
| * All on disk structures are in little-endian format. The end |
| * of the exceptions info is indicated by an exception with a |
| * new_chunk of 0, which is invalid since it would point to the |
| * header chunk. |
| */ |
| |
| /* |
| * Magic for persistent snapshots: "SnAp" - Feeble isn't it. |
| */ |
| #define SNAP_MAGIC 0x70416e53 |
| |
| /* |
| * The on-disk version of the metadata. |
| */ |
| #define SNAPSHOT_DISK_VERSION 1 |
| |
| #define NUM_SNAPSHOT_HDR_CHUNKS 1 |
| |
| struct disk_header { |
| uint32_t magic; |
| |
| /* |
| * Is this snapshot valid. There is no way of recovering |
| * an invalid snapshot. |
| */ |
| uint32_t valid; |
| |
| /* |
| * Simple, incrementing version. no backward |
| * compatibility. |
| */ |
| uint32_t version; |
| |
| /* In sectors */ |
| uint32_t chunk_size; |
| }; |
| |
| struct disk_exception { |
| uint64_t old_chunk; |
| uint64_t new_chunk; |
| }; |
| |
| struct commit_callback { |
| void (*callback)(void *, int success); |
| void *context; |
| }; |
| |
| /* |
| * The top level structure for a persistent exception store. |
| */ |
| struct pstore { |
| struct dm_exception_store *store; |
| int version; |
| int valid; |
| uint32_t exceptions_per_area; |
| |
| /* |
| * Now that we have an asynchronous kcopyd there is no |
| * need for large chunk sizes, so it wont hurt to have a |
| * whole chunks worth of metadata in memory at once. |
| */ |
| void *area; |
| |
| /* |
| * An area of zeros used to clear the next 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. |
| */ |
| chunk_t current_area; |
| |
| /* |
| * 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; |
| |
| /* |
| * The index of next free exception in the current |
| * metadata area. |
| */ |
| uint32_t current_committed; |
| |
| atomic_t pending_count; |
| uint32_t callback_count; |
| struct commit_callback *callbacks; |
| struct dm_io_client *io_client; |
| |
| struct workqueue_struct *metadata_wq; |
| }; |
| |
| static int alloc_area(struct pstore *ps) |
| { |
| int r = -ENOMEM; |
| size_t len; |
| |
| len = ps->store->chunk_size << SECTOR_SHIFT; |
| |
| /* |
| * Allocate the chunk_size block of memory that will hold |
| * a single metadata area. |
| */ |
| ps->area = vmalloc(len); |
| if (!ps->area) |
| goto err_area; |
| |
| ps->zero_area = vmalloc(len); |
| 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) |
| { |
| if (ps->area) |
| vfree(ps->area); |
| ps->area = NULL; |
| |
| 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 { |
| struct dm_io_region *where; |
| struct dm_io_request *io_req; |
| struct work_struct work; |
| int result; |
| }; |
| |
| static void do_metadata(struct work_struct *work) |
| { |
| struct mdata_req *req = container_of(work, struct mdata_req, work); |
| |
| req->result = dm_io(req->io_req, 1, req->where, NULL); |
| } |
| |
| /* |
| * Read or write a chunk aligned and sized block of data from a device. |
| */ |
| static int chunk_io(struct pstore *ps, void *area, chunk_t chunk, int rw, |
| int metadata) |
| { |
| struct dm_io_region where = { |
| .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 = area, |
| .client = ps->io_client, |
| .notify.fn = NULL, |
| }; |
| struct mdata_req req; |
| |
| if (!metadata) |
| return dm_io(&io_req, 1, &where, NULL); |
| |
| req.where = &where; |
| req.io_req = &io_req; |
| |
| /* |
| * Issue the synchronous I/O from a different thread |
| * to avoid generic_make_request recursion. |
| */ |
| INIT_WORK_ONSTACK(&req.work, do_metadata); |
| queue_work(ps->metadata_wq, &req.work); |
| flush_work(&req.work); |
| |
| return req.result; |
| } |
| |
| /* |
| * Convert a metadata area index to a chunk index. |
| */ |
| static chunk_t area_location(struct pstore *ps, chunk_t area) |
| { |
| return NUM_SNAPSHOT_HDR_CHUNKS + ((ps->exceptions_per_area + 1) * area); |
| } |
| |
| /* |
| * Read or write a metadata area. Remembering to skip the first |
| * chunk which holds the header. |
| */ |
| static int area_io(struct pstore *ps, int rw) |
| { |
| int r; |
| chunk_t chunk; |
| |
| chunk = area_location(ps, ps->current_area); |
| |
| r = chunk_io(ps, ps->area, chunk, rw, 0); |
| if (r) |
| return r; |
| |
| return 0; |
| } |
| |
| static void zero_memory_area(struct pstore *ps) |
| { |
| memset(ps->area, 0, ps->store->chunk_size << SECTOR_SHIFT); |
| } |
| |
| static int zero_disk_area(struct pstore *ps, chunk_t area) |
| { |
| 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; |
| unsigned chunk_size; |
| int chunk_size_supplied = 1; |
| char *chunk_err; |
| |
| /* |
| * 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(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(); |
| if (IS_ERR(ps->io_client)) |
| return PTR_ERR(ps->io_client); |
| |
| r = alloc_area(ps); |
| if (r) |
| return r; |
| |
| r = chunk_io(ps, ps->header_area, 0, READ, 1); |
| if (r) |
| goto bad; |
| |
| dh = ps->header_area; |
| |
| if (le32_to_cpu(dh->magic) == 0) { |
| *new_snapshot = 1; |
| return 0; |
| } |
| |
| if (le32_to_cpu(dh->magic) != SNAP_MAGIC) { |
| DMWARN("Invalid or corrupt snapshot"); |
| r = -ENXIO; |
| goto bad; |
| } |
| |
| *new_snapshot = 0; |
| ps->valid = le32_to_cpu(dh->valid); |
| ps->version = le32_to_cpu(dh->version); |
| chunk_size = le32_to_cpu(dh->chunk_size); |
| |
| if (ps->store->chunk_size == chunk_size) |
| return 0; |
| |
| 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); |
| |
| 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 = alloc_area(ps); |
| return r; |
| |
| bad: |
| free_area(ps); |
| return r; |
| } |
| |
| static int write_header(struct pstore *ps) |
| { |
| struct disk_header *dh; |
| |
| memset(ps->header_area, 0, ps->store->chunk_size << SECTOR_SHIFT); |
| |
| 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->store->chunk_size); |
| |
| return chunk_io(ps, ps->header_area, 0, WRITE, 1); |
| } |
| |
| /* |
| * Access functions for the disk exceptions, these do the endian conversions. |
| */ |
| static struct disk_exception *get_exception(struct pstore *ps, uint32_t index) |
| { |
| BUG_ON(index >= ps->exceptions_per_area); |
| |
| return ((struct disk_exception *) ps->area) + index; |
| } |
| |
| static void read_exception(struct pstore *ps, |
| uint32_t index, struct disk_exception *result) |
| { |
| struct disk_exception *e = get_exception(ps, index); |
| |
| /* copy it */ |
| result->old_chunk = le64_to_cpu(e->old_chunk); |
| result->new_chunk = le64_to_cpu(e->new_chunk); |
| } |
| |
| static void write_exception(struct pstore *ps, |
| uint32_t index, struct disk_exception *de) |
| { |
| struct disk_exception *e = get_exception(ps, index); |
| |
| /* copy it */ |
| e->old_chunk = cpu_to_le64(de->old_chunk); |
| 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 |
| * filled. |
| */ |
| static int insert_exceptions(struct pstore *ps, |
| int (*callback)(void *callback_context, |
| chunk_t old, chunk_t new), |
| void *callback_context, |
| int *full) |
| { |
| int r; |
| unsigned int i; |
| struct disk_exception de; |
| |
| /* presume the area is full */ |
| *full = 1; |
| |
| for (i = 0; i < ps->exceptions_per_area; i++) { |
| read_exception(ps, i, &de); |
| |
| /* |
| * If the new_chunk is pointing at the start of |
| * the COW device, where the first metadata area |
| * is we know that we've hit the end of the |
| * exceptions. Therefore the area is not full. |
| */ |
| if (de.new_chunk == 0LL) { |
| ps->current_committed = i; |
| *full = 0; |
| break; |
| } |
| |
| /* |
| * Keep track of the start of the free chunks. |
| */ |
| if (ps->next_free <= de.new_chunk) |
| ps->next_free = de.new_chunk + 1; |
| |
| /* |
| * Otherwise we add the exception to the snapshot. |
| */ |
| r = callback(callback_context, de.old_chunk, de.new_chunk); |
| if (r) |
| return r; |
| } |
| |
| return 0; |
| } |
| |
| static int read_exceptions(struct pstore *ps, |
| int (*callback)(void *callback_context, chunk_t old, |
| chunk_t new), |
| void *callback_context) |
| { |
| int r, full = 1; |
| |
| /* |
| * Keeping reading chunks and inserting exceptions until |
| * we find a partially full area. |
| */ |
| for (ps->current_area = 0; full; ps->current_area++) { |
| r = area_io(ps, READ); |
| if (r) |
| return r; |
| |
| r = insert_exceptions(ps, callback, callback_context, &full); |
| if (r) |
| return r; |
| } |
| |
| ps->current_area--; |
| |
| return 0; |
| } |
| |
| static struct pstore *get_info(struct dm_exception_store *store) |
| { |
| return (struct pstore *) store->context; |
| } |
| |
| static void persistent_usage(struct dm_exception_store *store, |
| sector_t *total_sectors, |
| sector_t *sectors_allocated, |
| sector_t *metadata_sectors) |
| { |
| 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) |
| { |
| struct pstore *ps = get_info(store); |
| |
| destroy_workqueue(ps->metadata_wq); |
| |
| /* 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); |
| } |
| |
| static int persistent_read_metadata(struct dm_exception_store *store, |
| int (*callback)(void *callback_context, |
| chunk_t old, chunk_t new), |
| void *callback_context) |
| { |
| int r, uninitialized_var(new_snapshot); |
| struct pstore *ps = get_info(store); |
| |
| /* |
| * Read the snapshot header. |
| */ |
| r = read_header(ps, &new_snapshot); |
| if (r) |
| return r; |
| |
| /* |
| * Now we know correct chunk_size, complete the initialisation. |
| */ |
| 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)); |
| if (!ps->callbacks) |
| return -ENOMEM; |
| |
| /* |
| * Do we need to setup a new snapshot ? |
| */ |
| if (new_snapshot) { |
| r = write_header(ps); |
| if (r) { |
| DMWARN("write_header failed"); |
| return r; |
| } |
| |
| ps->current_area = 0; |
| zero_memory_area(ps); |
| r = zero_disk_area(ps, 0); |
| if (r) |
| DMWARN("zero_disk_area(0) failed"); |
| 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; |
| |
| /* |
| * Read the metadata. |
| */ |
| r = read_exceptions(ps, callback, callback_context); |
| |
| return r; |
| } |
| |
| static int persistent_prepare_exception(struct dm_exception_store *store, |
| struct dm_exception *e) |
| { |
| struct pstore *ps = get_info(store); |
| uint32_t stride; |
| chunk_t next_free; |
| 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)) |
| return -ENOSPC; |
| |
| e->new_chunk = ps->next_free; |
| |
| /* |
| * Move onto the next free pending, making sure to take |
| * into account the location of the metadata chunks. |
| */ |
| stride = (ps->exceptions_per_area + 1); |
| next_free = ++ps->next_free; |
| if (sector_div(next_free, stride) == 1) |
| ps->next_free++; |
| |
| atomic_inc(&ps->pending_count); |
| return 0; |
| } |
| |
| static void persistent_commit_exception(struct dm_exception_store *store, |
| struct dm_exception *e, |
| void (*callback) (void *, int success), |
| void *callback_context) |
| { |
| unsigned int i; |
| struct pstore *ps = get_info(store); |
| struct disk_exception de; |
| struct commit_callback *cb; |
| |
| de.old_chunk = e->old_chunk; |
| de.new_chunk = e->new_chunk; |
| write_exception(ps, ps->current_committed++, &de); |
| |
| /* |
| * Add the callback to the back of the array. This code |
| * is the only place where the callback array is |
| * manipulated, and we know that it will never be called |
| * multiple times concurrently. |
| */ |
| cb = ps->callbacks + ps->callback_count++; |
| cb->callback = callback; |
| cb->context = callback_context; |
| |
| /* |
| * If there are exceptions in flight and we have not yet |
| * filled this metadata area there's nothing more to do. |
| */ |
| if (!atomic_dec_and_test(&ps->pending_count) && |
| (ps->current_committed != ps->exceptions_per_area)) |
| return; |
| |
| /* |
| * If we completely filled the current area, then wipe the next one. |
| */ |
| if ((ps->current_committed == ps->exceptions_per_area) && |
| zero_disk_area(ps, ps->current_area + 1)) |
| ps->valid = 0; |
| |
| /* |
| * Commit exceptions to disk. |
| */ |
| if (ps->valid && area_io(ps, WRITE_FLUSH_FUA)) |
| ps->valid = 0; |
| |
| /* |
| * Advance to the next area if this one is full. |
| */ |
| if (ps->current_committed == ps->exceptions_per_area) { |
| ps->current_committed = 0; |
| ps->current_area++; |
| zero_memory_area(ps); |
| } |
| |
| for (i = 0; i < ps->callback_count; i++) { |
| cb = ps->callbacks + i; |
| cb->callback(cb->context, ps->valid); |
| } |
| |
| 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_FLUSH_FUA); |
| 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) + |
| ps->current_committed + 1; |
| |
| return 0; |
| } |
| |
| static void persistent_drop_snapshot(struct dm_exception_store *store) |
| { |
| struct pstore *ps = get_info(store); |
| |
| ps->valid = 0; |
| if (write_header(ps)) |
| DMWARN("write header failed"); |
| } |
| |
| static int persistent_ctr(struct dm_exception_store *store, |
| unsigned argc, char **argv) |
| { |
| struct pstore *ps; |
| |
| /* allocate the pstore */ |
| ps = kzalloc(sizeof(*ps), GFP_KERNEL); |
| if (!ps) |
| return -ENOMEM; |
| |
| ps->store = store; |
| ps->valid = 1; |
| ps->version = SNAPSHOT_DISK_VERSION; |
| ps->area = NULL; |
| 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; |
| atomic_set(&ps->pending_count, 0); |
| ps->callbacks = NULL; |
| |
| ps->metadata_wq = alloc_workqueue("ksnaphd", WQ_MEM_RECLAIM, 0); |
| if (!ps->metadata_wq) { |
| kfree(ps); |
| DMERR("couldn't start header metadata update thread"); |
| return -ENOMEM; |
| } |
| |
| 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) |
| { |
| 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); |
| } |