The topmost file used to initialize and unload the exception store. Signed-off-by: Mikulas Patocka --- drivers/md/multisnap/dm-multisnap-mikulas.c | 757 ++++++++++++++++++++++++++++ 1 file changed, 757 insertions(+) Index: linux-2.6.36-rc7-fast/drivers/md/multisnap/dm-multisnap-mikulas.c =================================================================== --- /dev/null 1970-01-01 00:00:00.000000000 +0000 +++ linux-2.6.36-rc7-fast/drivers/md/multisnap/dm-multisnap-mikulas.c 2010-10-15 03:18:18.000000000 +0200 @@ -0,0 +1,757 @@ +/* + * Copyright (C) 2009 Red Hat Czech, s.r.o. + * + * Mikulas Patocka + * + * This file is released under the GPL. + */ + +#include "dm-multisnap-mikulas.h" + +/* + * Initialize in-memory structures, belonging to the commit block. + */ +static void init_commit_block(struct dm_exception_store *s) +{ + int i; + + dm_multisnap_init_freelist(s->freelist, s->chunk_size); + + s->snapshot_num = 0; + s->total_allocated = 0; + s->data_allocated = 0; + s->bitmap_root = 0; + s->alloc_rover = 0; + s->freelist_ptr = 0; + s->delete_rover_chunk = 0; + s->delete_rover_snapid = 0; + s->bt_root = 0; + s->bt_depth = 0; + s->flags = 0; + + for (i = 0; i < TMP_REMAP_HASH_SIZE; i++) + INIT_HLIST_HEAD(&s->tmp_remap[i]); + s->n_used_tmp_remaps = 0; + INIT_LIST_HEAD(&s->used_bitmap_tmp_remaps); + INIT_LIST_HEAD(&s->used_bt_tmp_remaps); + INIT_LIST_HEAD(&s->free_tmp_remaps); + + for (i = 0; i < N_REMAPS; i++) { + struct tmp_remap *t = &s->tmp_remap_store[i]; + list_add(&t->list, &s->free_tmp_remaps); + } + + s->dev_size = 0; + s->bitmap_depth = 0; + s->btree_entries = dm_multisnap_btree_entries(s->chunk_size); +} + +static struct multisnap_commit_block *read_commit_block(struct dm_exception_store *s, + chunk_t chunk, + struct dm_buffer **bp) +{ + struct multisnap_commit_block *cb; + cb = dm_bufio_read(s->bufio, chunk, bp); + if (unlikely(IS_ERR(cb))) { + DM_MULTISNAP_SET_ERROR(s->dm, PTR_ERR(cb), + ("%s: can't read commit block %llx", + __func__, (unsigned long long)chunk)); + return NULL; + } + if (unlikely(cb->signature != CB_SIGNATURE)) { + dm_bufio_release(*bp); + DM_MULTISNAP_SET_ERROR(s->dm, -EFSERROR, + ("%s: bad signature on commit block %llx", + __func__, (unsigned long long)chunk)); + return NULL; + } + if (unlikely(read_48(cb, self) != chunk)) { + dm_bufio_release(*bp); + DM_MULTISNAP_SET_ERROR(s->dm, -EFSERROR, + ("%s: self pointer is invalid on commit block %llx: %llx", + __func__, + (unsigned long long)chunk, + (unsigned long long)read_48(cb, self))); + return NULL; + } + return cb; +} + +/* + * Load the commit block specified in s->valid_commit_block to memory + * and populate in-memory structures. + */ +static void load_commit_block(struct dm_exception_store *s) +{ + struct dm_buffer *bp; + struct multisnap_commit_block *cb; + __u64 dev_size; + int bitmap_depth; + unsigned i; + + dm_multisnap_clear_uncommitted(s); + + cb = read_commit_block(s, s->valid_commit_block, &bp); + if (!cb) + return; + + init_commit_block(s); + + dev_size = read_48(cb, dev_size); + s->snapshot_num = le32_to_cpu(cb->snapshot_num); + s->total_allocated = read_48(cb, total_allocated); + s->data_allocated = read_48(cb, data_allocated); + s->bitmap_root = read_48(cb, bitmap_root); + s->alloc_rover = read_48(cb, alloc_rover); + s->freelist_ptr = read_48(cb, freelist); + s->delete_rover_chunk = read_48(cb, delete_rover); + s->delete_rover_snapid = 0; + s->bt_root = read_48(cb, bt_root); + s->bt_depth = cb->bt_depth; + s->flags = cb->flags; + + if (s->bt_depth > DM_MULTISNAP_MAX_BT_DEPTH || !s->bt_depth) { + dm_bufio_release(bp); + DM_MULTISNAP_SET_ERROR(s->dm, -EFSERROR, + ("%s: invalid b+-tree depth in commit block %llx", + __func__, (unsigned long long)s->valid_commit_block)); + return; + } + + INIT_LIST_HEAD(&s->free_tmp_remaps); + for (i = 0; i < N_REMAPS; i++) { + struct tmp_remap *t = &s->tmp_remap_store[i]; + if (read_48(&cb->tmp_remap[i], old)) { + t->old = read_48(&cb->tmp_remap[i], old); + t->new = read_48(&cb->tmp_remap[i], new); + t->uncommitted = 0; + t->bitmap_idx = le32_to_cpu(cb->tmp_remap[i].bitmap_idx); + hlist_add_head(&t->hash_list, &s->tmp_remap[TMP_REMAP_HASH(t->old)]); + if (t->bitmap_idx == CB_BITMAP_IDX_NONE) + list_add(&t->list, &s->used_bt_tmp_remaps); + else + list_add(&t->list, &s->used_bitmap_tmp_remaps); + s->n_used_tmp_remaps++; + } else { + list_add(&t->list, &s->free_tmp_remaps); + } + } + + dm_bufio_release(bp); + + if ((chunk_t)(dev_size + s->cb_stride) < (chunk_t)dev_size) { + DM_MULTISNAP_SET_ERROR(s->dm, -ERANGE, + ("%s: device is too large. Compile kernel with 64-bit sector numbers", + __func__)); + return; + } + bitmap_depth = dm_multisnap_bitmap_depth(s->chunk_shift, dev_size); + if (bitmap_depth < 0) { + DM_MULTISNAP_SET_ERROR(s->dm, bitmap_depth, + ("%s: device is too large", __func__)); + return; + } + s->dev_size = dev_size; + s->bitmap_depth = bitmap_depth; + + dm_multisnap_load_freelist(s); +} + +/* + * Find the valid commit block. + * + * Read the initial commit block number from the superblock and then scan the + * commit blocks linearly as long as the sequence number in the commit block + * increases. + */ +static void find_commit_block(struct dm_exception_store *s) +{ + struct dm_buffer *bp; + struct multisnap_commit_block *cb; + chunk_t cb_addr = s->sb_commit_block; + __u64 sequence; + __u64 dev_size; + s->valid_commit_block = 0; + s->commit_sequence = 0; + +try_next: + cb = read_commit_block(s, cb_addr, &bp); + if (!cb) + return; + + sequence = le64_to_cpu(cb->sequence); + dev_size = read_48(cb, dev_size); + + dm_bufio_release(bp); + + if (sequence > s->commit_sequence) { + s->commit_sequence = sequence; + s->valid_commit_block = cb_addr; + if ((__u64)cb_addr + s->cb_stride < dev_size) { + cb_addr += s->cb_stride; + goto try_next; + } + } + if (!s->valid_commit_block) { + DM_MULTISNAP_SET_ERROR(s->dm, -EFSERROR, + ("%s: no valid commit block", __func__)); + return; + } +} + +/* + * Return device size in chunks. + */ +static int get_size(struct dm_exception_store *s, chunk_t *size) +{ + __u64 dev_size; + dev_size = i_size_read(dm_multisnap_snapshot_bdev(s->dm)->bd_inode) >> s->chunk_shift; + *size = dev_size; + if ((chunk_t)(dev_size + s->cb_stride) < dev_size) + return -EFBIG; + + return 0; +} + +/* + * Initialize the whole snapshot store. + */ +static void initialize_device(struct dm_exception_store *s) +{ + int r; + struct dm_buffer *bp; + struct multisnap_superblock *sb; + struct multisnap_commit_block *cb; + chunk_t cb_block; + chunk_t block_to_write; + + s->cb_stride = CB_STRIDE_DEFAULT; + + r = get_size(s, &s->dev_size); + if (r) { + DM_MULTISNAP_SET_ERROR(s->dm, r, + ("%s: device is too large. Compile kernel with 64-bit sector numbers", + __func__)); + return; + } + + s->total_allocated = 0; + s->data_allocated = 0; + + block_to_write = SB_BLOCK + 1; + + /* Write btree */ + dm_multisnap_create_btree(s, &block_to_write); + if (dm_multisnap_has_error(s->dm)) + return; + + /* Write bitmaps */ + dm_multisnap_create_bitmaps(s, &block_to_write); + if (dm_multisnap_has_error(s->dm)) + return; + + s->dev_size = block_to_write; + + /* Write commit blocks */ + if (FIRST_CB_BLOCK >= s->dev_size) { + DM_MULTISNAP_SET_ERROR(s->dm, -ENOSPC, + ("%s: device is too small", __func__)); + return; + } + for (cb_block = FIRST_CB_BLOCK; cb_block < s->dev_size; cb_block += s->cb_stride) { + cb = dm_bufio_new(s->bufio, cb_block, &bp); + if (IS_ERR(cb)) { + DM_MULTISNAP_SET_ERROR(s->dm, PTR_ERR(cb), + ("%s: can't allocate commit block at %llx", + __func__, (unsigned long long)cb_block)); + return; + } + memset(cb, 0, s->chunk_size); + cb->signature = CB_SIGNATURE; + cb->sequence = cpu_to_le64(cb_block == FIRST_CB_BLOCK ? DM_MULTISNAP_INIT_SEQUENCE : 0); + write_48(cb, self, cb_block); + if (cb_block == FIRST_CB_BLOCK) { + cb->snapshot_num = cpu_to_le32(0); + write_48(cb, dev_size, s->dev_size); + write_48(cb, total_allocated, s->total_allocated); + write_48(cb, data_allocated, s->data_allocated); + write_48(cb, bitmap_root, s->bitmap_root); + write_48(cb, freelist, 0); + write_48(cb, delete_rover, 0); + write_48(cb, bt_root, s->bt_root); + cb->bt_depth = s->bt_depth; + cb->flags = 0; + } + dm_bufio_mark_buffer_dirty(bp); + dm_bufio_release(bp); + } + r = dm_bufio_write_dirty_buffers(s->bufio); + if (r) { + DM_MULTISNAP_SET_ERROR(s->dm, r, + ("%s: write error when initializing device", __func__)); + return; + } + + /* Write super block */ + sb = dm_bufio_new(s->bufio, SB_BLOCK, &bp); + if (IS_ERR(sb)) { + DM_MULTISNAP_SET_ERROR(s->dm, PTR_ERR(sb), + ("%s: can't allocate super block", __func__)); + return; + } + memset(sb, 0, s->chunk_size); + sb->signature = SB_SIGNATURE; + sb->chunk_size = cpu_to_le32(s->chunk_size); + sb->cb_stride = cpu_to_le32(s->cb_stride); + sb->error = cpu_to_le32(0); + sb->commit_block = cpu_to_le64(FIRST_CB_BLOCK); + dm_bufio_mark_buffer_dirty(bp); + dm_bufio_release(bp); + r = dm_bufio_write_dirty_buffers(s->bufio); + if (r) { + DM_MULTISNAP_SET_ERROR(s->dm, r, + ("%s: can't write super block", __func__)); + return; + } +} + +/* + * Extend the snapshot store if its size increases. + * + * Note: the size can never decrease. + */ +static void extend_exception_store(struct dm_exception_store *s, chunk_t new_size) +{ + struct dm_buffer *bp; + chunk_t cb_block; + struct multisnap_commit_block *cb; + + /* Write commit blocks */ + for (cb_block = FIRST_CB_BLOCK; cb_block < new_size; cb_block += s->cb_stride) { + cond_resched(); + if (cb_block < s->dev_size) + continue; + cb = dm_bufio_new(s->bufio, cb_block, &bp); + if (IS_ERR(cb)) { + DM_MULTISNAP_SET_ERROR(s->dm, PTR_ERR(cb), + ("%s: can't allocate commit block at %llx", + __func__, (unsigned long long)cb_block)); + return; + } + memset(cb, 0, s->chunk_size); + cb->signature = CB_SIGNATURE; + cb->sequence = cpu_to_le64(0); + write_48(cb, self, cb_block); + dm_bufio_mark_buffer_dirty(bp); + dm_bufio_release(bp); + } + + dm_multisnap_extend_bitmaps(s, new_size); + + s->valid_commit_block = (chunk_t)-1; + + dm_multisnap_commit(s); +} + +/* + * Read the super block and possibly initialize the device. + * + * If the super block contains valid signature, we assume that the device + * is initialized and read all the data. + * If the super block is zeroed, we do initialization. + * Otherwise we report error. + */ +static int read_super(struct dm_exception_store *s, char **error) +{ + struct dm_buffer *bp; + struct multisnap_superblock *sb; + int initialized; + __s32 e; + + init_commit_block(s); + + initialized = 0; +re_read: + sb = dm_bufio_read(s->bufio, SB_BLOCK, &bp); + if (IS_ERR(sb)) { + *error = "Could not read superblock"; + return PTR_ERR(sb); + } + + if (sb->signature != SB_SIGNATURE) { + int i; + if (initialized) { + *error = "Invalid signature after initialization"; + return -EIO; + } + for (i = 0; i < 1 << SECTOR_SHIFT; i++) { + if (((char *)sb)[i]) { + dm_bufio_release(bp); + *error = "Uninitialized device"; + return -ENXIO; + } + } + dm_bufio_release(bp); + initialize_device(s); + if (dm_multisnap_has_error(s->dm)) { + *error = "Can't initialize device"; + return dm_multisnap_has_error(s->dm); + } + initialized = 1; + goto re_read; + } + if (le32_to_cpu(sb->chunk_size) != s->chunk_size) { + dm_bufio_release(bp); + *error = "Bad chunk size"; + return -EINVAL; + } + s->cb_stride = le32_to_cpu(sb->cb_stride); + if (s->cb_stride <= 1) { + dm_bufio_release(bp); + *error = "Bad commit block stride in superblock"; + return -EFSERROR; + } + s->sb_commit_block = le64_to_cpu(sb->commit_block); + e = le32_to_cpu(sb->error); + dm_bufio_release(bp); + + find_commit_block(s); + + if (dm_multisnap_has_error(s->dm)) { + if (dm_multisnap_drop_on_error(s->dm)) + return 0; + *error = "Unable to find commit block"; + return dm_multisnap_has_error(s->dm); + } + + load_commit_block(s); + + if (dm_multisnap_has_error(s->dm)) { + if (dm_multisnap_drop_on_error(s->dm)) + return 0; + *error = "Unable to load commit block"; + return dm_multisnap_has_error(s->dm); + } + + if (e < 0) { + /* Don't read the B+-tree if there was an error */ + DM_MULTISNAP_SET_ERROR(s->dm, e, + ("%s: activating invalidated snapshot store, error %d", + __func__, e)); + return 0; + } + + dm_multisnap_read_snapshots(s); + if (dm_multisnap_has_error(s->dm)) { + if (dm_multisnap_drop_on_error(s->dm)) + return 0; + *error = "Could not read snapshot list"; + return dm_multisnap_has_error(s->dm); + } + + return 0; +} + +/* + * This is a callback that is being called each time the generic code acquires + * the master lock. Thus, it is guaranteed that other operations won't race with + * this callback. + * + * Currently, we test if the device size has grown, and if so, we extend the + * exception store. + * + * If the device size has shrunk, we report an error and stop further + * operations. + */ +static void dm_multisnap_mikulas_lock_acquired(struct dm_exception_store *s, int flags) +{ + int r; + chunk_t new_size; + + if (dm_multisnap_has_error(s->dm)) + return; + + if (!dm_multisnap_can_commit(s->dm)) + return; + + r = get_size(s, &new_size); + if (unlikely(r)) + return; + + if (unlikely(new_size != s->dev_size)) { + if (unlikely(new_size < s->dev_size)) { + DM_MULTISNAP_SET_ERROR(s->dm, -EINVAL, + ("%s: device shrank", __func__)); + return; + } + extend_exception_store(s, new_size); + } +} + +/* + * Debug code. + */ + +/*#define PRINT_BTREE*/ + +#ifdef PRINT_BTREE +static int print_btree_callback(struct dm_exception_store *s, + struct dm_multisnap_bt_node *node, + struct dm_multisnap_bt_entry *bt, void *cookie) +{ + printk(KERN_DEBUG "entry: %llx, %llx-%llx -> %llx\n", + (unsigned long long)read_48(bt, orig_chunk), + (unsigned long long)cpu_to_mikulas_snapid(bt->snap_from), + (unsigned long long)cpu_to_mikulas_snapid(bt->snap_to), + (unsigned long long)read_48(bt, new_chunk)); + return 0; +} + +static void print_btree(struct dm_exception_store *s) +{ + struct bt_key key = { 0, 0, 0 }; + int r = dm_multisnap_list_btree(s, &key, print_btree_callback, NULL); + printk(KERN_DEBUG "list ended: %d\n", r); +} +#endif + +/*#define PRINT_BITMAPS*/ + +#ifdef PRINT_BITMAPS +static void print_bitmaps(struct dm_exception_store *s) +{ + chunk_t c; + printk(KERN_DEBUG "allocated:"); + for (c = 0; c < s->dev_size; c += s->chunk_size * 8) { + struct dm_buffer *bp; + unsigned i; + void *bmp = dm_multisnap_map_bitmap(s, c >> (s->chunk_shift + 3), + &bp, NULL, NULL); + if (!bmp) + continue; + for (i = 0; i < s->chunk_size * 8; i++) + if (generic_test_le_bit(i, bmp)) { + chunk_t block = c + i; + if (!dm_multisnap_is_commit_block(s, block)) + printk(" %llx", (unsigned long long)block); + cond_resched(); + } + } + + dm_bufio_release(bp); + } + printk("\n"); +} +#endif + +/* + * The initialization callback. + * Parse arguments, allocate structures and call read_super to read the data + * from the disk. + */ +static int dm_multisnap_mikulas_init(struct dm_multisnap *dm, + struct dm_exception_store **sp, + unsigned argc, char **argv, char **error) +{ + int r, i; + struct dm_exception_store *s; + + s = kzalloc(sizeof(struct dm_exception_store), GFP_KERNEL); + if (!s) { + *error = "Could not allocate private area"; + r = -ENOMEM; + goto bad_private; + } + *sp = s; + + s->dm = dm; + s->chunk_size = dm_multisnap_chunk_size(dm); + s->chunk_shift = ffs(s->chunk_size) - 1; + + if (s->chunk_size > 256 * 1024 * 1024) { + *error = "Too bug chunk size (maximum is 256MiB)"; + r = -EINVAL; + goto bad_arguments; + } + + s->active_snapshots = RB_ROOT; + s->n_preallocated_blocks = 0; + s->query_active = 0; + + s->delete_work.work = dm_multisnap_background_delete; + s->delete_work.queued = 0; + s->delete_commit_count = 0; + + for (i = 0; i < UNCOMMITTED_BLOCK_HASH_SIZE; i++) + INIT_HLIST_HEAD(&s->uncommitted_blocks[i]); + + while (argc) { + char *string; + r = dm_multisnap_get_string(&argv, &argc, &string, error); + if (r) + goto bad_arguments; + /* + * Add test for future arguments here. + * Also, regenerate the arguments in the "status_table" + * callback. + */ + { + *error = "Unknown parameter"; + r = -EINVAL; + goto bad_arguments; + } + } + + + s->tmp_chunk = vmalloc(s->chunk_size + sizeof(struct dm_multisnap_bt_entry)); + if (!s->tmp_chunk) { + *error = "Can't allocate temporary chunk"; + r = -ENOMEM; + goto bad_tmp_chunk; + } + + s->freelist = vmalloc(s->chunk_size); + if (!s->freelist) { + *error = "Can't allocate freelist"; + r = -ENOMEM; + goto bad_freelist; + } + + s->bufio = dm_bufio_client_create(dm_multisnap_snapshot_bdev(s->dm), + s->chunk_size); + if (IS_ERR(s->bufio)) { + *error = "Can't create bufio client"; + r = PTR_ERR(s->bufio); + goto bad_bufio; + } + + r = read_super(s, error); + if (r) + goto bad_super; + + if (s->flags & (DM_MULTISNAP_FLAG_DELETING | + DM_MULTISNAP_FLAG_PENDING_DELETE)) + dm_multisnap_queue_work(s->dm, &s->delete_work); + + /* Extend the snapshot store */ + dm_multisnap_mikulas_lock_acquired(s, 0); + +#ifdef PRINT_BTREE + print_btree(s); +#endif +#ifdef PRINT_BITMAPS + print_bitmaps(s); +#endif + + return 0; + +bad_super: + dm_bufio_client_destroy(s->bufio); +bad_bufio: + vfree(s->freelist); +bad_freelist: + vfree(s->tmp_chunk); +bad_tmp_chunk: +bad_arguments: + kfree(s); +bad_private: + return r; +} + +/* + * Exit the exception store. + */ +static void dm_multisnap_mikulas_exit(struct dm_exception_store *s) +{ + int i; + + dm_multisnap_cancel_work(s->dm, &s->delete_work); + + i = 0; + while (!list_empty(&s->used_bitmap_tmp_remaps)) { + struct tmp_remap *t = list_first_entry(&s->used_bitmap_tmp_remaps, + struct tmp_remap, list); + list_del(&t->list); + hlist_del(&t->hash_list); + i++; + } + + while (!list_empty(&s->used_bt_tmp_remaps)) { + struct tmp_remap *t = list_first_entry(&s->used_bt_tmp_remaps, + struct tmp_remap, list); + list_del(&t->list); + hlist_del(&t->hash_list); + i++; + } + + BUG_ON(i != s->n_used_tmp_remaps); + while (!list_empty(&s->free_tmp_remaps)) { + struct tmp_remap *t = list_first_entry(&s->free_tmp_remaps, struct tmp_remap, list); + list_del(&t->list); + i++; + } + BUG_ON(i != N_REMAPS); + + for (i = 0; i < TMP_REMAP_HASH_SIZE; i++) + BUG_ON(!hlist_empty(&s->tmp_remap[i])); + + dm_multisnap_clear_uncommitted(s); + + dm_bufio_client_destroy(s->bufio); + vfree(s->freelist); + vfree(s->tmp_chunk); + kfree(s); +} + +struct dm_multisnap_exception_store dm_multisnap_mikulas_store = { + .name = "mikulas", + .module = THIS_MODULE, + .init_exception_store = dm_multisnap_mikulas_init, + .exit_exception_store = dm_multisnap_mikulas_exit, + .store_lock_acquired = dm_multisnap_mikulas_lock_acquired, +#ifdef CONFIG_DM_MULTISNAPSHOT_MIKULAS_SNAP_OF_SNAP + .print_snapid = dm_multisnap_print_snapid, + .read_snapid = dm_multisnap_read_snapid, +#endif + .get_space = dm_multisnap_get_space, + .allocate_snapid = dm_multisnap_allocate_snapid, + .create_snapshot = dm_multisnap_create_snapshot, + .delete_snapshot = dm_multisnap_delete_snapshot, + .get_next_snapid = dm_multisnap_get_next_snapid, + .compare_snapids_for_create = dm_multisnap_compare_snapids_for_create, + .find_snapshot_chunk = dm_multisnap_find_snapshot_chunk, + .start_origin_query = dm_multisnap_start_origin_query, + .query_next_remap = dm_multisnap_query_next_remap, + .add_next_remap = dm_multisnap_add_next_remap, + .make_chunk_writeable = dm_multisnap_make_chunk_writeable, + .check_conflict = dm_multisnap_check_conflict, + .prepare_for_commit = dm_multisnap_prepare_for_commit, + .commit = dm_multisnap_commit, +}; + +static int __init dm_multisnapshot_mikulas_module_init(void) +{ + int r; + BUG_ON(sizeof(struct multisnap_commit_block) != 512); + + r = dm_multisnap_register_exception_store(&dm_multisnap_mikulas_store); + if (r) + goto cant_register; + + return 0; + +cant_register: + return r; +} + +static void __exit dm_multisnapshot_mikulas_module_exit(void) +{ + dm_multisnap_unregister_exception_store(&dm_multisnap_mikulas_store); +} + +module_init(dm_multisnapshot_mikulas_module_init); +module_exit(dm_multisnapshot_mikulas_module_exit); + +MODULE_DESCRIPTION(DM_NAME " multisnapshot Mikulas' exceptions store"); +MODULE_AUTHOR("Mikulas Patocka"); +MODULE_LICENSE("GPL");