--- /dev/null
+/*
+ * Copyright (C) 2011 Red Hat, Inc. All rights reserved.
+ *
+ * This file is released under the GPL.
+ */
+
+#include "dm-thin-metadata.h"
+#include "persistent-data/dm-btree.h"
+#include "persistent-data/dm-space-map.h"
+#include "persistent-data/dm-space-map-disk.h"
+#include "persistent-data/dm-transaction-manager.h"
+
+#include <linux/list.h>
+#include <linux/device-mapper.h>
+#include <linux/workqueue.h>
+
+/*--------------------------------------------------------------------------
+ * As far as the metadata goes, there is:
+ *
+ * - A superblock in block zero, taking up fewer than 512 bytes for
+ * atomic writes.
+ *
+ * - A space map managing the metadata blocks.
+ *
+ * - A space map managing the data blocks.
+ *
+ * - A btree mapping our internal thin dev ids onto struct disk_device_details.
+ *
+ * - A hierarchical btree, with 2 levels which effectively maps (thin
+ * dev id, virtual block) -> block_time. Block time is a 64-bit
+ * field holding the time in the low 24 bits, and block in the top 48
+ * bits.
+ *
+ * BTrees consist solely of btree_nodes, that fill a block. Some are
+ * internal nodes, as such their values are a __le64 pointing to other
+ * nodes. Leaf nodes can store data of any reasonable size (ie. much
+ * smaller than the block size). The nodes consist of the header,
+ * followed by an array of keys, followed by an array of values. We have
+ * to binary search on the keys so they're all held together to help the
+ * cpu cache.
+ *
+ * Space maps have 2 btrees:
+ *
+ * - One maps a uint64_t onto a struct index_entry. Which points to a
+ * bitmap block, and has some details about how many free entries there
+ * are etc.
+ *
+ * - The bitmap blocks have a header (for the checksum). Then the rest
+ * of the block is pairs of bits. With the meaning being:
+ *
+ * 0 - ref count is 0
+ * 1 - ref count is 1
+ * 2 - ref count is 2
+ * 3 - ref count is higher than 2
+ *
+ * - If the count is higher than 2 then the ref count is entered in a
+ * second btree that directly maps the block_address to a uint32_t ref
+ * count.
+ *
+ * The space map metadata variant doesn't have a bitmaps btree. Instead
+ * it has one single blocks worth of index_entries. This avoids
+ * recursive issues with the bitmap btree needing to allocate space in
+ * order to insert. With a small data block size such as 64k the
+ * metadata support data devices that are hundreds of terrabytes.
+ *
+ * The space maps allocate space linearly from front to back. Space that
+ * is freed in a transaction is never recycled within that transaction.
+ * To try and avoid fragmenting _free_ space the allocator always goes
+ * back and fills in gaps.
+ *
+ * All metadata io is in THIN_METADATA_BLOCK_SIZE sized/aligned chunks
+ * from the block manager.
+ *--------------------------------------------------------------------------*/
+
+#define DM_MSG_PREFIX "thin metadata"
+
+#define THIN_SUPERBLOCK_MAGIC 27022010
+#define THIN_SUPERBLOCK_LOCATION 0
+#define THIN_VERSION 1
+#define THIN_METADATA_BLOCK_SIZE 4096
+#define THIN_METADATA_CACHE_SIZE 64
+#define SECTOR_TO_BLOCK_SHIFT 3
+
+/* This should be plenty */
+#define SPACE_MAP_ROOT_SIZE 128
+
+/*
+ * Little endian on-disk superblock and device details.
+ */
+struct thin_disk_superblock {
+ __le32 csum; /* Checksum of superblock except for this field. */
+ __le32 flags;
+ __le64 blocknr; /* This block number, dm_block_t. */
+
+ __u8 uuid[16];
+ __le64 magic;
+ __le32 version;
+ __le32 time;
+
+ __le64 trans_id;
+
+ /*
+ * Root held by userspace transactions.
+ */
+ __le64 held_root;
+
+ __u8 data_space_map_root[SPACE_MAP_ROOT_SIZE];
+ __u8 metadata_space_map_root[SPACE_MAP_ROOT_SIZE];
+
+ /*
+ * 2-level btree mapping (dev_id, (dev block, time)) -> data block
+ */
+ __le64 data_mapping_root;
+
+ /*
+ * Device detail root mapping dev_id -> device_details
+ */
+ __le64 device_details_root;
+
+ __le32 data_block_size; /* In 512-byte sectors. */
+
+ __le32 metadata_block_size; /* In 512-byte sectors. */
+ __le64 metadata_nr_blocks;
+
+ __le32 compat_flags;
+ __le32 compat_ro_flags;
+ __le32 incompat_flags;
+} __packed;
+
+struct disk_device_details {
+ __le64 mapped_blocks;
+ __le64 transaction_id; /* When created. */
+ __le32 creation_time;
+ __le32 snapshotted_time;
+} __packed;
+
+struct dm_pool_metadata {
+ struct hlist_node hash;
+
+ struct block_device *bdev;
+ struct dm_block_manager *bm;
+ struct dm_space_map *metadata_sm;
+ struct dm_space_map *data_sm;
+ struct dm_transaction_manager *tm;
+ struct dm_transaction_manager *nb_tm;
+
+ /*
+ * Two-level btree.
+ * First level holds thin_dev_t.
+ * Second level holds mappings.
+ */
+ struct dm_btree_info info;
+
+ /*
+ * Non-blocking version of the above.
+ */
+ struct dm_btree_info nb_info;
+
+ /*
+ * Just the top level for deleting whole devices.
+ */
+ struct dm_btree_info tl_info;
+
+ /*
+ * Just the bottom level for creating new devices.
+ */
+ struct dm_btree_info bl_info;
+
+ /*
+ * Describes the device details btree.
+ */
+ struct dm_btree_info details_info;
+
+ struct rw_semaphore root_lock;
+ uint32_t time;
+ int need_commit;
+ struct dm_block *sblock;
+ dm_block_t root;
+ dm_block_t details_root;
+ struct list_head thin_devices;
+ uint64_t trans_id;
+ unsigned long flags;
+ sector_t data_block_size;
+};
+
+struct dm_thin_device {
+ struct list_head list;
+ struct dm_pool_metadata *pmd;
+ dm_thin_id id;
+
+ int open_count;
+ int changed;
+ uint64_t mapped_blocks;
+ uint64_t transaction_id;
+ uint32_t creation_time;
+ uint32_t snapshotted_time;
+};
+
+/*----------------------------------------------------------------
+ * superblock validator
+ *--------------------------------------------------------------*/
+
+static void sb_prepare_for_write(struct dm_block_validator *v,
+ struct dm_block *b,
+ size_t block_size)
+{
+ struct thin_disk_superblock *disk_super = dm_block_data(b);
+
+ disk_super->blocknr = cpu_to_le64(dm_block_location(b));
+ disk_super->csum = cpu_to_le32(dm_block_csum_data(&disk_super->flags, sizeof(*disk_super) - sizeof(__le32)));
+}
+
+static int sb_check(struct dm_block_validator *v,
+ struct dm_block *b,
+ size_t block_size)
+{
+ struct thin_disk_superblock *disk_super = dm_block_data(b);
+ __le32 csum_le;
+
+ if (dm_block_location(b) != le64_to_cpu(disk_super->blocknr)) {
+ DMERR("sb_check failed: blocknr %llu: "
+ "wanted %llu", le64_to_cpu(disk_super->blocknr),
+ (unsigned long long)dm_block_location(b));
+ return -ENOTBLK;
+ }
+
+ if (le64_to_cpu(disk_super->magic) != THIN_SUPERBLOCK_MAGIC) {
+ DMERR("sb_check failed: magic %llu: "
+ "wanted %llu", le64_to_cpu(disk_super->magic),
+ (unsigned long long)THIN_SUPERBLOCK_MAGIC);
+ return -EILSEQ;
+ }
+
+ csum_le = cpu_to_le32(dm_block_csum_data(&disk_super->flags, sizeof(*disk_super) - sizeof(__le32)));
+ if (csum_le != disk_super->csum) {
+ DMERR("sb_check failed: csum %u: wanted %u",
+ le32_to_cpu(csum_le), le32_to_cpu(disk_super->csum));
+ return -EILSEQ;
+ }
+
+ return 0;
+}
+
+static struct dm_block_validator sb_validator = {
+ .name = "superblock",
+ .prepare_for_write = sb_prepare_for_write,
+ .check = sb_check
+};
+
+/*----------------------------------------------------------------
+ * Methods for the btree value types
+ *--------------------------------------------------------------*/
+
+static uint64_t pack_block_time(dm_block_t b, uint32_t t)
+{
+ return (b << 24) | t;
+}
+
+static void unpack_block_time(uint64_t v, dm_block_t *b, uint32_t *t)
+{
+ *b = v >> 24;
+ *t = v & ((1 << 24) - 1);
+}
+
+static void data_block_inc(void *context, void *value_le)
+{
+ struct dm_space_map *sm = context;
+ __le64 v_le;
+ uint64_t b;
+ uint32_t t;
+
+ memcpy(&v_le, value_le, sizeof(v_le));
+ unpack_block_time(le64_to_cpu(v_le), &b, &t);
+ dm_sm_inc_block(sm, b);
+}
+
+static void data_block_dec(void *context, void *value_le)
+{
+ struct dm_space_map *sm = context;
+ __le64 v_le;
+ uint64_t b;
+ uint32_t t;
+
+ memcpy(&v_le, value_le, sizeof(v_le));
+ unpack_block_time(le64_to_cpu(v_le), &b, &t);
+ dm_sm_dec_block(sm, b);
+}
+
+static int data_block_equal(void *context, void *value1_le, void *value2_le)
+{
+ __le64 v1_le, v2_le;
+ uint64_t b1, b2;
+ uint32_t t;
+
+ memcpy(&v1_le, value1_le, sizeof(v1_le));
+ memcpy(&v2_le, value2_le, sizeof(v2_le));
+ unpack_block_time(le64_to_cpu(v1_le), &b1, &t);
+ unpack_block_time(le64_to_cpu(v2_le), &b2, &t);
+
+ return b1 == b2;
+}
+
+static void subtree_inc(void *context, void *value)
+{
+ struct dm_btree_info *info = context;
+ __le64 root_le;
+ uint64_t root;
+
+ memcpy(&root_le, value, sizeof(root_le));
+ root = le64_to_cpu(root_le);
+ dm_tm_inc(info->tm, root);
+}
+
+static void subtree_dec(void *context, void *value)
+{
+ struct dm_btree_info *info = context;
+ __le64 root_le;
+ uint64_t root;
+
+ memcpy(&root_le, value, sizeof(root_le));
+ root = le64_to_cpu(root_le);
+ if (dm_btree_del(info, root))
+ DMERR("btree delete failed\n");
+}
+
+static int subtree_equal(void *context, void *value1_le, void *value2_le)
+{
+ __le64 v1_le, v2_le;
+ memcpy(&v1_le, value1_le, sizeof(v1_le));
+ memcpy(&v2_le, value2_le, sizeof(v2_le));
+
+ return v1_le == v2_le;
+}
+
+/*----------------------------------------------------------------*/
+
+static int superblock_all_zeroes(struct dm_block_manager *bm, int *result)
+{
+ int r;
+ unsigned i;
+ struct dm_block *b;
+ __le64 *data_le, zero = cpu_to_le64(0);
+ unsigned block_size = dm_bm_block_size(bm) / sizeof(__le64);
+
+ /*
+ * We can't use a validator here - it may be all zeroes.
+ */
+ r = dm_bm_read_lock(bm, THIN_SUPERBLOCK_LOCATION, NULL, &b);
+ if (r)
+ return r;
+
+ data_le = dm_block_data(b);
+ *result = 1;
+ for (i = 0; i < block_size; i++) {
+ if (data_le[i] != zero) {
+ *result = 0;
+ break;
+ }
+ }
+
+ return dm_bm_unlock(b);
+}
+
+static struct dm_pool_metadata *alloc_pmd(struct dm_block_manager *bm,
+ dm_block_t nr_blocks, int create)
+{
+ int r;
+ struct dm_space_map *sm, *data_sm;
+ struct dm_transaction_manager *tm;
+ struct dm_pool_metadata *pmd = NULL;
+ struct dm_block *sblock;
+
+ if (create) {
+ r = dm_tm_create_with_sm(bm, THIN_SUPERBLOCK_LOCATION,
+ &sb_validator, &tm, &sm, &sblock);
+ if (r < 0) {
+ DMERR("tm_create_with_sm failed");
+ return ERR_PTR(r);
+ }
+
+ data_sm = dm_sm_disk_create(tm, nr_blocks);
+ if (IS_ERR(data_sm)) {
+ DMERR("sm_disk_create failed");
+ r = PTR_ERR(data_sm);
+ goto bad;
+ }
+
+ r = dm_tm_pre_commit(tm);
+ if (r < 0) {
+ DMERR("couldn't pre commit");
+ goto bad_data_sm;
+ }
+
+ r = dm_tm_commit(tm, sblock);
+ if (r < 0) {
+ DMERR("couldn't commit");
+ goto bad_data_sm;
+ }
+ } else {
+ struct thin_disk_superblock *disk_super = NULL;
+ size_t space_map_root_offset =
+ offsetof(struct thin_disk_superblock, metadata_space_map_root);
+
+ r = dm_tm_open_with_sm(bm, THIN_SUPERBLOCK_LOCATION,
+ &sb_validator, space_map_root_offset,
+ SPACE_MAP_ROOT_SIZE, &tm, &sm, &sblock);
+ if (r < 0) {
+ DMERR("tm_open_with_sm failed");
+ return ERR_PTR(r);
+ }
+
+ disk_super = dm_block_data(sblock);
+ data_sm = dm_sm_disk_open(tm, disk_super->data_space_map_root,
+ sizeof(disk_super->data_space_map_root));
+ if (IS_ERR(data_sm)) {
+ DMERR("sm_disk_open failed");
+ r = PTR_ERR(data_sm);
+ goto bad;
+ }
+
+ dm_tm_unlock(tm, sblock);
+ }
+
+ pmd = kmalloc(sizeof(*pmd), GFP_KERNEL);
+ if (!pmd) {
+ DMERR("could not allocate metadata struct");
+ r = -ENOMEM;
+ goto bad_data_sm;
+ }
+
+ pmd->bm = bm;
+ pmd->metadata_sm = sm;
+ pmd->data_sm = data_sm;
+ pmd->tm = tm;
+ pmd->nb_tm = dm_tm_create_non_blocking_clone(tm);
+ if (!pmd->nb_tm) {
+ DMERR("could not create clone tm");
+ r = -ENOMEM;
+ goto bad_pmd;
+ }
+
+ pmd->sblock = NULL;
+
+ pmd->info.tm = tm;
+ pmd->info.levels = 2;
+ pmd->info.value_type.context = pmd->data_sm;
+ pmd->info.value_type.size = sizeof(__le64);
+ pmd->info.value_type.inc = data_block_inc;
+ pmd->info.value_type.dec = data_block_dec;
+ pmd->info.value_type.equal = data_block_equal;
+
+ memcpy(&pmd->nb_info, &pmd->info, sizeof(pmd->nb_info));
+ pmd->nb_info.tm = pmd->nb_tm;
+
+ pmd->tl_info.tm = tm;
+ pmd->tl_info.levels = 1;
+ pmd->tl_info.value_type.context = &pmd->info;
+ pmd->tl_info.value_type.size = sizeof(__le64);
+ pmd->tl_info.value_type.inc = subtree_inc;
+ pmd->tl_info.value_type.dec = subtree_dec;
+ pmd->tl_info.value_type.equal = subtree_equal;
+
+ pmd->bl_info.tm = tm;
+ pmd->bl_info.levels = 1;
+ pmd->bl_info.value_type.context = pmd->data_sm;
+ pmd->bl_info.value_type.size = sizeof(__le64);
+ pmd->bl_info.value_type.inc = data_block_inc;
+ pmd->bl_info.value_type.dec = data_block_dec;
+ pmd->bl_info.value_type.equal = data_block_equal;
+
+ pmd->details_info.tm = tm;
+ pmd->details_info.levels = 1;
+ pmd->details_info.value_type.context = NULL;
+ pmd->details_info.value_type.size = sizeof(struct disk_device_details);
+ pmd->details_info.value_type.inc = NULL;
+ pmd->details_info.value_type.dec = NULL;
+ pmd->details_info.value_type.equal = NULL;
+
+ pmd->root = 0;
+
+ init_rwsem(&pmd->root_lock);
+ pmd->time = 0;
+ pmd->need_commit = 0;
+ pmd->details_root = 0;
+ INIT_LIST_HEAD(&pmd->thin_devices);
+
+ return pmd;
+
+bad_pmd:
+ kfree(pmd);
+bad_data_sm:
+ dm_sm_destroy(data_sm);
+bad:
+ dm_tm_destroy(tm);
+ dm_sm_destroy(sm);
+
+ return ERR_PTR(r);
+}
+
+static int begin_transaction(struct dm_pool_metadata *pmd)
+{
+ int r;
+ u32 features;
+ struct thin_disk_superblock *disk_super;
+
+ /*
+ * dm_pool_commit_metadata() resets pmd->sblock
+ */
+ WARN_ON(pmd->sblock);
+ pmd->need_commit = 0;
+
+ /*
+ * superblock is unlocked via dm_tm_commit()
+ */
+ r = dm_bm_write_lock(pmd->bm, THIN_SUPERBLOCK_LOCATION,
+ &sb_validator, &pmd->sblock);
+ if (r)
+ return r;
+
+ disk_super = dm_block_data(pmd->sblock);
+ pmd->time = le32_to_cpu(disk_super->time);
+ pmd->root = le64_to_cpu(disk_super->data_mapping_root);
+ pmd->details_root = le64_to_cpu(disk_super->device_details_root);
+ pmd->trans_id = le64_to_cpu(disk_super->trans_id);
+ pmd->flags = le32_to_cpu(disk_super->flags);
+ pmd->data_block_size = le32_to_cpu(disk_super->data_block_size);
+
+ features = le32_to_cpu(disk_super->incompat_flags) & ~THIN_FEATURE_INCOMPAT_SUPP;
+ if (features) {
+ DMERR("could not access metadata due to "
+ "unsupported optional features (%lx).",
+ (unsigned long)features);
+ return -EINVAL;
+ }
+
+ /*
+ * Check for read-only metadata to skip the following RDWR checks.
+ */
+ if (get_disk_ro(pmd->bdev->bd_disk))
+ return 0;
+
+ features = le32_to_cpu(disk_super->compat_ro_flags) & ~THIN_FEATURE_COMPAT_RO_SUPP;
+ if (features) {
+ DMERR("could not access metadata RDWR due to "
+ "unsupported optional features (%lx).",
+ (unsigned long)features);
+ return -EINVAL;
+ }
+
+ return 0;
+}
+
+struct dm_pool_metadata *dm_pool_metadata_open(struct block_device *bdev,
+ sector_t data_block_size)
+{
+ int r;
+ struct thin_disk_superblock *disk_super;
+ struct dm_pool_metadata *pmd;
+ sector_t bdev_size = i_size_read(bdev->bd_inode) >> SECTOR_SHIFT;
+ struct dm_block_manager *bm;
+ int create;
+
+ bm = dm_block_manager_create(bdev, THIN_METADATA_BLOCK_SIZE,
+ THIN_METADATA_CACHE_SIZE, 3);
+ if (!bm) {
+ DMERR("could not create block manager");
+ return ERR_PTR(-ENOMEM);
+ }
+
+ r = superblock_all_zeroes(bm, &create);
+ if (r) {
+ dm_block_manager_destroy(bm);
+ return ERR_PTR(r);
+ }
+
+ pmd = alloc_pmd(bm, 0, create);
+ if (IS_ERR(pmd)) {
+ dm_block_manager_destroy(bm);
+ return pmd;
+ }
+ pmd->bdev = bdev;
+
+ if (!create) {
+ r = begin_transaction(pmd);
+ if (r < 0)
+ goto bad;
+ return pmd;
+ }
+
+ /*
+ * Create.
+ */
+ if (!pmd->sblock) {
+ r = begin_transaction(pmd);
+ if (r < 0)
+ goto bad;
+ }
+
+ disk_super = dm_block_data(pmd->sblock);
+ disk_super->magic = cpu_to_le64(THIN_SUPERBLOCK_MAGIC);
+ disk_super->version = cpu_to_le32(THIN_VERSION);
+ disk_super->time = 0;
+ disk_super->metadata_block_size = cpu_to_le32(THIN_METADATA_BLOCK_SIZE >> SECTOR_SHIFT);
+ disk_super->metadata_nr_blocks = cpu_to_le64(bdev_size >> SECTOR_TO_BLOCK_SHIFT);
+ disk_super->data_block_size = cpu_to_le32(data_block_size);
+
+ r = dm_btree_empty(&pmd->info, &pmd->root);
+ if (r < 0)
+ goto bad;
+
+ r = dm_btree_empty(&pmd->details_info, &pmd->details_root);
+ if (r < 0) {
+ DMERR("couldn't create devices root");
+ goto bad;
+ }
+
+ pmd->flags = 0;
+ pmd->need_commit = 1;
+ r = dm_pool_commit_metadata(pmd);
+ if (r < 0) {
+ DMERR("%s: dm_pool_commit_metadata() failed, error = %d",
+ __func__, r);
+ goto bad;
+ }
+
+ return pmd;
+
+bad:
+ if (dm_pool_metadata_close(pmd) < 0)
+ DMWARN("%s: dm_pool_metadata_close() failed.", __func__);
+ return ERR_PTR(r);
+}
+
+int dm_pool_metadata_close(struct dm_pool_metadata *pmd)
+{
+ int r;
+ unsigned open_devices = 0;
+ struct dm_thin_device *td, *tmp;
+
+ down_read(&pmd->root_lock);
+ list_for_each_entry_safe(td, tmp, &pmd->thin_devices, list) {
+ if (td->open_count)
+ open_devices++;
+ else {
+ list_del(&td->list);
+ kfree(td);
+ }
+ }
+ up_read(&pmd->root_lock);
+
+ if (open_devices) {
+ DMERR("attempt to close pmd when %u device(s) are still open",
+ open_devices);
+ return -EBUSY;
+ }
+
+ if (pmd->sblock) {
+ r = dm_pool_commit_metadata(pmd);
+ if (r)
+ DMWARN("%s: dm_pool_commit_metadata() failed, error = %d",
+ __func__, r);
+ }
+
+ dm_tm_destroy(pmd->tm);
+ dm_tm_destroy(pmd->nb_tm);
+ dm_block_manager_destroy(pmd->bm);
+ dm_sm_destroy(pmd->metadata_sm);
+ dm_sm_destroy(pmd->data_sm);
+ kfree(pmd);
+
+ return 0;
+}
+
+int dm_pool_rebind_metadata_device(struct dm_pool_metadata *pmd,
+ struct block_device *bdev)
+{
+ return dm_bm_rebind_block_device(pmd->bm, bdev);
+}
+
+static int __open_device(struct dm_pool_metadata *pmd,
+ dm_thin_id dev, int create,
+ struct dm_thin_device **td)
+{
+ int r, changed = 0;
+ struct dm_thin_device *td2;
+ uint64_t key = dev;
+ struct disk_device_details details_le;
+
+ /*
+ * If the device is already open, just increment its open_count.
+ */
+ list_for_each_entry(td2, &pmd->thin_devices, list)
+ if (td2->id == dev) {
+ td2->open_count++;
+ *td = td2;
+ return 0;
+ }
+
+ /*
+ * Check the device exists.
+ */
+ r = dm_btree_lookup(&pmd->details_info, pmd->details_root,
+ &key, &details_le);
+ if (r) {
+ if (r != -ENODATA || !create)
+ return r;
+
+ /*
+ * New device.
+ */
+ changed = 1;
+ details_le.mapped_blocks = 0;
+ details_le.transaction_id = cpu_to_le64(pmd->trans_id);
+ details_le.creation_time = cpu_to_le32(pmd->time);
+ details_le.snapshotted_time = cpu_to_le32(pmd->time);
+ }
+
+ *td = kmalloc(sizeof(**td), GFP_NOIO);
+ if (!*td)
+ return -ENOMEM;
+
+ (*td)->pmd = pmd;
+ (*td)->id = dev;
+ (*td)->open_count = 1;
+ (*td)->changed = changed;
+ (*td)->mapped_blocks = le64_to_cpu(details_le.mapped_blocks);
+ (*td)->transaction_id = le64_to_cpu(details_le.transaction_id);
+ (*td)->creation_time = le32_to_cpu(details_le.creation_time);
+ (*td)->snapshotted_time = le32_to_cpu(details_le.snapshotted_time);
+
+ list_add(&(*td)->list, &pmd->thin_devices);
+
+ return 0;
+}
+
+static void __close_device(struct dm_thin_device *td)
+{
+ --td->open_count;
+}
+
+static int __create_thin(struct dm_pool_metadata *pmd,
+ dm_thin_id dev)
+{
+ int r;
+ dm_block_t dev_root;
+ uint64_t key = dev;
+ struct disk_device_details details_le;
+ struct dm_thin_device *td;
+ __le64 value;
+
+ r = dm_btree_lookup(&pmd->details_info, pmd->details_root,
+ &key, &details_le);
+ if (!r)
+ return -EEXIST;
+
+ /*
+ * Create an empty btree for the mappings.
+ */
+ r = dm_btree_empty(&pmd->bl_info, &dev_root);
+ if (r)
+ return r;
+
+ /*
+ * Insert it into the main mapping tree.
+ */
+ value = cpu_to_le64(dev_root);
+ __dm_bless_for_disk(&value);
+ r = dm_btree_insert(&pmd->tl_info, pmd->root, &key, &value, &pmd->root);
+ if (r) {
+ dm_btree_del(&pmd->bl_info, dev_root);
+ return r;
+ }
+
+ r = __open_device(pmd, dev, 1, &td);
+ if (r) {
+ __close_device(td);
+ dm_btree_remove(&pmd->tl_info, pmd->root, &key, &pmd->root);
+ dm_btree_del(&pmd->bl_info, dev_root);
+ return r;
+ }
+ td->changed = 1;
+ __close_device(td);
+
+ return r;
+}
+
+int dm_pool_create_thin(struct dm_pool_metadata *pmd, dm_thin_id dev)
+{
+ int r;
+
+ down_write(&pmd->root_lock);
+ r = __create_thin(pmd, dev);
+ up_write(&pmd->root_lock);
+
+ return r;
+}
+
+static int __set_snapshot_details(struct dm_pool_metadata *pmd,
+ struct dm_thin_device *snap,
+ dm_thin_id origin, uint32_t time)
+{
+ int r;
+ struct dm_thin_device *td;
+
+ r = __open_device(pmd, origin, 0, &td);
+ if (r)
+ return r;
+
+ td->changed = 1;
+ td->snapshotted_time = time;
+
+ snap->mapped_blocks = td->mapped_blocks;
+ snap->snapshotted_time = time;
+ __close_device(td);
+
+ return 0;
+}
+
+static int __create_snap(struct dm_pool_metadata *pmd,
+ dm_thin_id dev, dm_thin_id origin)
+{
+ int r;
+ dm_block_t origin_root, snap_root;
+ uint64_t key = origin, dev_key = dev;
+ struct dm_thin_device *td;
+ struct disk_device_details details_le;
+ __le64 value;
+
+ /* check this device is unused */
+ r = dm_btree_lookup(&pmd->details_info, pmd->details_root,
+ &dev_key, &details_le);
+ if (!r)
+ return -EEXIST;
+
+ /* find the mapping tree for the origin */
+ r = dm_btree_lookup(&pmd->tl_info, pmd->root, &key, &value);
+ if (r)
+ return r;
+ origin_root = le64_to_cpu(value);
+
+ /* clone the origin */
+ r = dm_btree_clone(&pmd->bl_info, origin_root, &snap_root);
+ if (r)
+ return r;
+
+ /* insert into the main mapping tree */
+ value = cpu_to_le64(snap_root);
+ __dm_bless_for_disk(&value);
+ key = dev;
+ r = dm_btree_insert(&pmd->tl_info, pmd->root, &key, &value, &pmd->root);
+ if (r) {
+ dm_btree_del(&pmd->bl_info, snap_root);
+ return r;
+ }
+
+ pmd->time++;
+
+ r = __open_device(pmd, dev, 1, &td);
+ if (r)
+ goto bad;
+
+ r = __set_snapshot_details(pmd, td, origin, pmd->time);
+ if (r)
+ goto bad;
+
+ __close_device(td);
+ return 0;
+
+bad:
+ __close_device(td);
+ dm_btree_remove(&pmd->tl_info, pmd->root, &key, &pmd->root);
+ dm_btree_remove(&pmd->details_info, pmd->details_root,
+ &key, &pmd->details_root);
+ return r;
+}
+
+int dm_pool_create_snap(struct dm_pool_metadata *pmd,
+ dm_thin_id dev,
+ dm_thin_id origin)
+{
+ int r;
+
+ down_write(&pmd->root_lock);
+ r = __create_snap(pmd, dev, origin);
+ up_write(&pmd->root_lock);
+
+ return r;
+}
+
+static int __delete_device(struct dm_pool_metadata *pmd, dm_thin_id dev)
+{
+ int r;
+ uint64_t key = dev;
+ struct dm_thin_device *td;
+
+ /* TODO: failure should mark the transaction invalid */
+ r = __open_device(pmd, dev, 0, &td);
+ if (r)
+ return r;
+
+ if (td->open_count > 1) {
+ __close_device(td);
+ return -EBUSY;
+ }
+
+ list_del(&td->list);
+ kfree(td);
+ r = dm_btree_remove(&pmd->details_info, pmd->details_root,
+ &key, &pmd->details_root);
+ if (r)
+ return r;
+
+ r = dm_btree_remove(&pmd->tl_info, pmd->root, &key, &pmd->root);
+ if (r)
+ return r;
+
+ pmd->need_commit = 1;
+
+ return 0;
+}
+
+int dm_pool_delete_thin_device(struct dm_pool_metadata *pmd,
+ dm_thin_id dev)
+{
+ int r;
+
+ down_write(&pmd->root_lock);
+ r = __delete_device(pmd, dev);
+ up_write(&pmd->root_lock);
+
+ return r;
+}
+
+static int __trim_thin_dev(struct dm_thin_device *td, sector_t new_size)
+{
+ struct dm_pool_metadata *pmd = td->pmd;
+ /* FIXME: convert new size to blocks */
+ uint64_t key[2] = { td->id, new_size - 1 };
+
+ td->changed = 1;
+
+ /*
+ * We need to truncate all the extraneous mappings.
+ *
+ * FIXME: We have to be careful to do this atomically.
+ * Perhaps clone the bottom layer first so we can revert?
+ */
+ return dm_btree_del_gt(&pmd->info, pmd->root, key, &pmd->root);
+}
+
+int dm_pool_trim_thin_device(struct dm_pool_metadata *pmd, dm_thin_id dev,
+ sector_t new_size)
+{
+ int r;
+ struct dm_thin_device *td;
+
+ down_write(&pmd->root_lock);
+ r = __open_device(pmd, dev, 1, &td);
+ if (r)
+ DMERR("couldn't open virtual device");
+ else {
+ r = __trim_thin_dev(td, new_size);
+ __close_device(td);
+ }
+
+ /* FIXME: update mapped_blocks */
+
+ up_write(&pmd->root_lock);
+
+ return r;
+}
+
+int dm_pool_set_metadata_transaction_id(struct dm_pool_metadata *pmd,
+ uint64_t current_id,
+ uint64_t new_id)
+{
+ down_write(&pmd->root_lock);
+ if (pmd->trans_id != current_id) {
+ up_write(&pmd->root_lock);
+ DMERR("mismatched transaction id");
+ return -EINVAL;
+ }
+
+ pmd->trans_id = new_id;
+ pmd->need_commit = 1;
+ up_write(&pmd->root_lock);
+
+ return 0;
+}
+
+int dm_pool_get_metadata_transaction_id(struct dm_pool_metadata *pmd,
+ uint64_t *result)
+{
+ down_read(&pmd->root_lock);
+ *result = pmd->trans_id;
+ up_read(&pmd->root_lock);
+
+ return 0;
+}
+
+int dm_pool_get_held_metadata_root(struct dm_pool_metadata *pmd,
+ dm_block_t *result)
+{
+ struct thin_disk_superblock *disk_super;
+
+ down_read(&pmd->root_lock);
+ disk_super = dm_block_data(pmd->sblock);
+ *result = le64_to_cpu(disk_super->held_root);
+ up_read(&pmd->root_lock);
+
+ return 0;
+}
+
+int dm_pool_open_thin_device(struct dm_pool_metadata *pmd, dm_thin_id dev,
+ struct dm_thin_device **td)
+{
+ int r;
+
+ down_write(&pmd->root_lock);
+ r = __open_device(pmd, dev, 0, td);
+ up_write(&pmd->root_lock);
+
+ return r;
+}
+
+int dm_pool_close_thin_device(struct dm_thin_device *td)
+{
+ down_write(&td->pmd->root_lock);
+ __close_device(td);
+ up_write(&td->pmd->root_lock);
+
+ return 0;
+}
+
+dm_thin_id dm_thin_dev_id(struct dm_thin_device *td)
+{
+ return td->id;
+}
+
+static int __snapshotted_since(struct dm_thin_device *td, uint32_t time)
+{
+ return td->snapshotted_time > time;
+}
+
+int dm_thin_find_block(struct dm_thin_device *td, dm_block_t block,
+ int can_block, struct dm_thin_lookup_result *result)
+{
+ int r;
+ uint64_t block_time = 0;
+ __le64 value;
+ struct dm_pool_metadata *pmd = td->pmd;
+ dm_block_t keys[2] = { td->id, block };
+
+ if (can_block) {
+ down_read(&pmd->root_lock);
+ r = dm_btree_lookup(&pmd->info, pmd->root, keys, &value);
+ if (!r)
+ block_time = le64_to_cpu(value);
+ up_read(&pmd->root_lock);
+
+ } else if (down_read_trylock(&pmd->root_lock)) {
+ r = dm_btree_lookup(&pmd->nb_info, pmd->root, keys, &value);
+ if (!r)
+ block_time = le64_to_cpu(value);
+ up_read(&pmd->root_lock);
+
+ } else
+ return -EWOULDBLOCK;
+
+ if (!r) {
+ dm_block_t exception_block;
+ uint32_t exception_time;
+ unpack_block_time(block_time, &exception_block,
+ &exception_time);
+ result->block = exception_block;
+ result->shared = __snapshotted_since(td, exception_time);
+ }
+
+ return r;
+}
+
+static int __insert(struct dm_thin_device *td, dm_block_t block,
+ dm_block_t data_block)
+{
+ int r, inserted;
+ __le64 value;
+ struct dm_pool_metadata *pmd = td->pmd;
+ dm_block_t keys[2] = { td->id, block };
+
+ pmd->need_commit = 1;
+ value = cpu_to_le64(pack_block_time(data_block, pmd->time));
+ __dm_bless_for_disk(&value);
+
+ r = dm_btree_insert_notify(&pmd->info, pmd->root, keys, &value,
+ &pmd->root, &inserted);
+ if (r)
+ return r;
+
+ if (inserted) {
+ td->mapped_blocks++;
+ td->changed = 1;
+ }
+
+ return 0;
+}
+
+int dm_thin_insert_block(struct dm_thin_device *td, dm_block_t block,
+ dm_block_t data_block)
+{
+ int r;
+
+ down_write(&td->pmd->root_lock);
+ r = __insert(td, block, data_block);
+ up_write(&td->pmd->root_lock);
+
+ return r;
+}
+
+static int __remove(struct dm_thin_device *td, dm_block_t block)
+{
+ int r;
+ struct dm_pool_metadata *pmd = td->pmd;
+ dm_block_t keys[2] = { td->id, block };
+
+ r = dm_btree_remove(&pmd->info, pmd->root, keys, &pmd->root);
+ if (r)
+ return r;
+
+ pmd->need_commit = 1;
+
+ return 0;
+}
+
+int dm_thin_remove_block(struct dm_thin_device *td, dm_block_t block)
+{
+ int r;
+
+ down_write(&td->pmd->root_lock);
+ r = __remove(td, block);
+ up_write(&td->pmd->root_lock);
+
+ return r;
+}
+
+int dm_pool_alloc_data_block(struct dm_pool_metadata *pmd, dm_block_t *result)
+{
+ int r;
+
+ down_write(&pmd->root_lock);
+
+ r = dm_sm_new_block(pmd->data_sm, result);
+ pmd->need_commit = 1;
+
+ up_write(&pmd->root_lock);
+
+ return r;
+}
+
+static int __write_changed_details(struct dm_pool_metadata *pmd)
+{
+ int r;
+ struct dm_thin_device *td, *tmp;
+ struct disk_device_details details;
+ uint64_t key;
+
+ list_for_each_entry_safe(td, tmp, &pmd->thin_devices, list) {
+ if (!td->changed)
+ continue;
+
+ key = td->id;
+
+ details.mapped_blocks = cpu_to_le64(td->mapped_blocks);
+ details.transaction_id = cpu_to_le64(td->transaction_id);
+ details.creation_time = cpu_to_le32(td->creation_time);
+ details.snapshotted_time = cpu_to_le32(td->snapshotted_time);
+ __dm_bless_for_disk(&details);
+
+ r = dm_btree_insert(&pmd->details_info, pmd->details_root,
+ &key, &details, &pmd->details_root);
+ if (r)
+ return r;
+
+ if (td->open_count)
+ td->changed = 0;
+ else {
+ list_del(&td->list);
+ kfree(td);
+ }
+
+ pmd->need_commit = 1;
+ }
+
+ return 0;
+}
+
+int dm_pool_commit_metadata(struct dm_pool_metadata *pmd)
+{
+ /*
+ * FIXME: associated pool should be made read-only on
+ * dm_pool_commit_metadata failure.
+ */
+ int r;
+ size_t len;
+ struct thin_disk_superblock *disk_super;
+
+ /*
+ * We need to know if the thin_disk_superblock exceeds a 512-byte sector.
+ */
+ BUILD_BUG_ON(sizeof(struct thin_disk_superblock) > 512);
+
+ down_write(&pmd->root_lock);
+ r = __write_changed_details(pmd);
+ if (r < 0)
+ goto out;
+
+ if (!pmd->need_commit)
+ goto out;
+
+ r = dm_tm_pre_commit(pmd->tm);
+ if (r < 0)
+ goto out;
+
+ r = dm_sm_root_size(pmd->metadata_sm, &len);
+ if (r < 0)
+ goto out;
+
+ disk_super = dm_block_data(pmd->sblock);
+ disk_super->time = cpu_to_le32(pmd->time);
+ disk_super->data_mapping_root = cpu_to_le64(pmd->root);
+ disk_super->device_details_root = cpu_to_le64(pmd->details_root);
+ disk_super->trans_id = cpu_to_le64(pmd->trans_id);
+ disk_super->flags = cpu_to_le32(pmd->flags);
+
+ r = dm_sm_copy_root(pmd->metadata_sm, &disk_super->metadata_space_map_root, len);
+ if (r < 0)
+ goto out;
+
+ r = dm_sm_copy_root(pmd->data_sm, &disk_super->data_space_map_root, len);
+ if (r < 0)
+ goto out;
+
+ r = dm_tm_commit(pmd->tm, pmd->sblock);
+ if (r < 0)
+ goto out;
+
+ /*
+ * Open the next transaction.
+ */
+ pmd->sblock = NULL;
+
+ r = begin_transaction(pmd);
+out:
+ up_write(&pmd->root_lock);
+ return r;
+}
+
+int dm_pool_get_free_block_count(struct dm_pool_metadata *pmd, dm_block_t *result)
+{
+ int r;
+
+ down_read(&pmd->root_lock);
+ r = dm_sm_get_nr_free(pmd->data_sm, result);
+ up_read(&pmd->root_lock);
+
+ return r;
+}
+
+int dm_pool_get_free_metadata_block_count(struct dm_pool_metadata *pmd,
+ dm_block_t *result)
+{
+ int r;
+
+ down_read(&pmd->root_lock);
+ r = dm_sm_get_nr_free(pmd->metadata_sm, result);
+ up_read(&pmd->root_lock);
+
+ return r;
+}
+
+int dm_pool_get_data_block_size(struct dm_pool_metadata *pmd, sector_t *result)
+{
+ down_read(&pmd->root_lock);
+ *result = pmd->data_block_size;
+ up_read(&pmd->root_lock);
+
+ return 0;
+}
+
+int dm_pool_get_data_dev_size(struct dm_pool_metadata *pmd, dm_block_t *result)
+{
+ int r;
+
+ down_read(&pmd->root_lock);
+ r = dm_sm_get_nr_blocks(pmd->data_sm, result);
+ up_read(&pmd->root_lock);
+
+ return r;
+}
+
+int dm_thin_get_mapped_count(struct dm_thin_device *td, dm_block_t *result)
+{
+ struct dm_pool_metadata *pmd = td->pmd;
+
+ down_read(&pmd->root_lock);
+ *result = td->mapped_blocks;
+ up_read(&pmd->root_lock);
+
+ return 0;
+}
+
+static int __highest_block(struct dm_thin_device *td, dm_block_t *result)
+{
+ int r;
+ __le64 value_le;
+ dm_block_t thin_root;
+ struct dm_pool_metadata *pmd = td->pmd;
+
+ r = dm_btree_lookup(&pmd->tl_info, pmd->root, &td->id, &value_le);
+ if (r)
+ return r;
+
+ thin_root = le64_to_cpu(value_le);
+
+ return dm_btree_find_highest_key(&pmd->bl_info, thin_root, result);
+}
+
+int dm_thin_get_highest_mapped_block(struct dm_thin_device *td,
+ dm_block_t *result)
+{
+ int r;
+ struct dm_pool_metadata *pmd = td->pmd;
+
+ down_read(&pmd->root_lock);
+ r = __highest_block(td, result);
+ up_read(&pmd->root_lock);
+
+ return r;
+}
+
+static int __resize_data_dev(struct dm_pool_metadata *pmd, dm_block_t new_count)
+{
+ int r;
+ dm_block_t old_count;
+
+ r = dm_sm_get_nr_blocks(pmd->data_sm, &old_count);
+ if (r)
+ return r;
+
+ if (new_count == old_count)
+ return 0;
+
+ if (new_count < old_count) {
+ DMERR("cannot reduce size of data device");
+ return -EINVAL;
+ }
+
+ r = dm_sm_extend(pmd->data_sm, new_count - old_count);
+ if (!r)
+ pmd->need_commit = 1;
+
+ return r;
+}
+
+int dm_pool_resize_data_dev(struct dm_pool_metadata *pmd, dm_block_t new_count)
+{
+ int r;
+
+ down_write(&pmd->root_lock);
+ r = __resize_data_dev(pmd, new_count);
+ up_write(&pmd->root_lock);
+
+ return r;
+}
--- /dev/null
+/*
+ * Copyright (C) 2011 Red Hat UK. All rights reserved.
+ *
+ * This file is released under the GPL.
+ */
+
+#include "dm-thin-metadata.h"
+
+#include <linux/device-mapper.h>
+#include <linux/dm-io.h>
+#include <linux/dm-kcopyd.h>
+#include <linux/list.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+
+#define DM_MSG_PREFIX "thin"
+
+/*
+ * Tunable constants
+ */
+#define ENDIO_HOOK_POOL_SIZE 10240
+#define DEFERRED_SET_SIZE 64
+#define MAPPING_POOL_SIZE 1024
+#define PRISON_CELLS 1024
+
+/*
+ * The block size of the device holding pool data must be
+ * between 64KB and 1GB.
+ */
+#define DATA_DEV_BLOCK_SIZE_MIN_SECTORS (64 * 1024 >> SECTOR_SHIFT)
+#define DATA_DEV_BLOCK_SIZE_MAX_SECTORS (1024 * 1024 * 1024 >> SECTOR_SHIFT)
+
+#define METADATA_DEV_MAX_SECTORS (255 * (1 << 14) * 8)
+
+/*
+ * Device id is restricted to 24 bits.
+ */
+#define MAX_DEV_ID ((1 << 24) - 1)
+
+/*
+ * How do we handle breaking sharing of data blocks?
+ * =================================================
+ *
+ * We use a standard copy-on-write btree to store the mappings for the
+ * devices (note I'm talking about copy-on-write of the metadata here, not
+ * the data). When you take an internal snapshot you clone the root node
+ * of the origin btree. After this there is no concept of an origin or a
+ * snapshot. They are just two device trees that happen to point to the
+ * same data blocks.
+ *
+ * When we get a write in we decide if it's to a shared data block using
+ * some timestamp magic. If it is, we have to break sharing.
+ *
+ * Let's say we write to a shared block in what was the origin. The
+ * steps are:
+ *
+ * i) plug io further to this physical block. (see bio_prison code).
+ *
+ * ii) quiesce any read io to that shared data block. Obviously
+ * including all devices that share this block. (see deferred_set code)
+ *
+ * iii) copy the data block to a newly allocate block. This step can be
+ * missed out if the io covers the block. (schedule_copy).
+ *
+ * iv) insert the new mapping into the origin's btree
+ * (process_prepared_mappings). This act of inserting breaks some
+ * sharing of btree nodes between the two devices. Breaking sharing only
+ * effects the btree of that specific device. Btrees for the other
+ * devices that share the block never change. The btree for the origin
+ * device as it was after the last commit is untouched, ie. we're using
+ * persistent data structures in the functional programming sense.
+ *
+ * v) unplug io to this physical block, including the io that triggered
+ * the breaking of sharing.
+ *
+ * Steps (ii) and (iii) occur in parallel.
+ *
+ * The metadata _doesn't_ need to be committed before the io continues. We
+ * get away with this because the io is always written to a _new_ block.
+ * If there's a crash, then:
+ *
+ * - The origin mapping will point to the old origin block (the shared
+ * one). This will contain the data as it was before the io that triggered
+ * the breaking of sharing came in.
+ *
+ * - The snap mapping still points to the old block. As it would after
+ * the commit.
+ *
+ * The downside of this scheme is the timestamp magic isn't perfect, and
+ * will continue to think that data block in the snapshot device is shared
+ * even after the write to the origin has broken sharing. I suspect data
+ * blocks will typically be shared by many different devices, so we're
+ * breaking sharing n + 1 times, rather than n, where n is the number of
+ * devices that reference this data block. At the moment I think the
+ * benefits far, far outweigh the disadvantages.
+ */
+
+/*----------------------------------------------------------------*/
+
+/*
+ * Sometimes we can't deal with a bio straight away. We put them in prison
+ * where they can't cause any mischief. Bios are put in a cell identified
+ * by a key, multiple bios can be in the same cell. When the cell is
+ * subsequently unlocked the bios become available.
+ */
+struct bio_prison;
+
+struct cell_key {
+ int virtual;
+ dm_thin_id dev;
+ dm_block_t block;
+};
+
+struct cell {
+ struct hlist_node list;
+ struct bio_prison *prison;
+ struct cell_key key;
+ unsigned count;
+ struct bio_list bios;
+};
+
+struct bio_prison {
+ spinlock_t lock;
+ mempool_t *cell_pool;
+
+ unsigned nr_buckets;
+ unsigned hash_mask;
+ struct hlist_head *cells;
+};
+
+static uint32_t calc_nr_buckets(unsigned nr_cells)
+{
+ uint32_t n = 128;
+
+ nr_cells /= 4;
+ nr_cells = min(nr_cells, 8192u);
+
+ while (n < nr_cells)
+ n <<= 1;
+
+ return n;
+}
+
+/*
+ * @nr_cells should be the number of cells you want in use _concurrently_.
+ * Don't confuse it with the number of distinct keys.
+ */
+static struct bio_prison *prison_create(unsigned nr_cells)
+{
+ unsigned i;
+ uint32_t nr_buckets = calc_nr_buckets(nr_cells);
+ size_t len = sizeof(struct bio_prison) +
+ (sizeof(struct hlist_head) * nr_buckets);
+ struct bio_prison *prison = kmalloc(len, GFP_KERNEL);
+
+ if (!prison)
+ return NULL;
+
+ spin_lock_init(&prison->lock);
+ prison->cell_pool = mempool_create_kmalloc_pool(nr_cells,
+ sizeof(struct cell));
+ prison->nr_buckets = nr_buckets;
+ prison->hash_mask = nr_buckets - 1;
+ prison->cells = (struct hlist_head *) (prison + 1);
+ for (i = 0; i < nr_buckets; i++)
+ INIT_HLIST_HEAD(prison->cells + i);
+
+ return prison;
+}
+
+static void prison_destroy(struct bio_prison *prison)
+{
+ mempool_destroy(prison->cell_pool);
+ kfree(prison);
+}
+
+static uint32_t hash_key(struct bio_prison *prison, struct cell_key *key)
+{
+ const unsigned long BIG_PRIME = 4294967291UL;
+ uint64_t hash = key->block * BIG_PRIME;
+
+ return (uint32_t) (hash & prison->hash_mask);
+}
+
+static struct cell *__search_bucket(struct hlist_head *bucket,
+ struct cell_key *key)
+{
+ struct cell *cell;
+ struct hlist_node *tmp;
+
+ hlist_for_each_entry(cell, tmp, bucket, list)
+ if (!memcmp(&cell->key, key, sizeof(cell->key)))
+ return cell;
+
+ return NULL;
+}
+
+/*
+ * This may block if a new cell needs allocating. You must ensure that
+ * cells will be unlocked even if the calling thread is blocked.
+ *
+ * Returns the number of entries in the cell prior to the new addition
+ * or < 0 on failure.
+ */
+static int bio_detain(struct bio_prison *prison, struct cell_key *key,
+ struct bio *inmate, struct cell **ref)
+{
+ int r;
+ unsigned long flags;
+ uint32_t hash = hash_key(prison, key);
+ struct cell *uninitialized_var(cell), *cell2 = NULL;
+
+ BUG_ON(hash > prison->nr_buckets);
+
+ spin_lock_irqsave(&prison->lock, flags);
+ cell = __search_bucket(prison->cells + hash, key);
+
+ if (!cell) {
+ /*
+ * Allocate a new cell
+ */
+ spin_unlock_irqrestore(&prison->lock, flags);
+ cell2 = mempool_alloc(prison->cell_pool, GFP_NOIO);
+ spin_lock_irqsave(&prison->lock, flags);
+
+ /*
+ * We've been unlocked, so we have to double check that
+ * nobody else has inserted this cell in the meantime.
+ */
+ cell = __search_bucket(prison->cells + hash, key);
+
+ if (!cell) {
+ cell = cell2;
+ cell2 = NULL;
+
+ cell->prison = prison;
+ memcpy(&cell->key, key, sizeof(cell->key));
+ cell->count = 0;
+ bio_list_init(&cell->bios);
+ hlist_add_head(&cell->list, prison->cells + hash);
+ }
+ }
+
+ r = cell->count++;
+ bio_list_add(&cell->bios, inmate);
+ spin_unlock_irqrestore(&prison->lock, flags);
+
+ if (cell2)
+ mempool_free(cell2, prison->cell_pool);
+
+ *ref = cell;
+
+ return r;
+}
+
+/*
+ * @inmates must have been initialised prior to this call
+ */
+static void __cell_release(struct cell *cell, struct bio_list *inmates)
+{
+ struct bio_prison *prison = cell->prison;
+
+ hlist_del(&cell->list);
+
+ if (inmates)
+ bio_list_merge(inmates, &cell->bios);
+
+ mempool_free(cell, prison->cell_pool);
+}
+
+static void cell_release(struct cell *cell, struct bio_list *bios)
+{
+ unsigned long flags;
+ struct bio_prison *prison = cell->prison;
+
+ spin_lock_irqsave(&prison->lock, flags);
+ __cell_release(cell, bios);
+ spin_unlock_irqrestore(&prison->lock, flags);
+}
+
+/*
+ * There are a couple of places where we put a bio into a cell briefly
+ * before taking it out again. In these situations we know that no other
+ * bio may be in the cell. This function releases the cell, and also does
+ * a sanity check.
+ */
+static void cell_release_singleton(struct cell *cell, struct bio *bio)
+{
+ struct bio_prison *prison = cell->prison;
+ struct bio_list bios;
+ struct bio *b;
+ unsigned long flags;
+
+ bio_list_init(&bios);
+
+ spin_lock_irqsave(&prison->lock, flags);
+ __cell_release(cell, &bios);
+ spin_unlock_irqrestore(&prison->lock, flags);
+
+ b = bio_list_pop(&bios);
+ BUG_ON(b != bio);
+ BUG_ON(!bio_list_empty(&bios));
+}
+
+static void cell_error(struct cell *cell)
+{
+ struct bio_prison *prison = cell->prison;
+ struct bio_list bios;
+ struct bio *bio;
+ unsigned long flags;
+
+ bio_list_init(&bios);
+
+ spin_lock_irqsave(&prison->lock, flags);
+ __cell_release(cell, &bios);
+ spin_unlock_irqrestore(&prison->lock, flags);
+
+ while ((bio = bio_list_pop(&bios)))
+ bio_io_error(bio);
+}
+
+/*----------------------------------------------------------------*/
+
+/*
+ * We use the deferred set to keep track of pending reads to shared blocks.
+ * We do this to ensure the new mapping caused by a write isn't performed
+ * until these prior reads have completed. Otherwise the insertion of the
+ * new mapping could free the old block that the read bios are mapped to.
+ */
+
+struct deferred_set;
+struct deferred_entry {
+ struct deferred_set *ds;
+ unsigned count;
+ struct list_head work_items;
+};
+
+struct deferred_set {
+ spinlock_t lock;
+ unsigned current_entry;
+ unsigned sweeper;
+ struct deferred_entry entries[DEFERRED_SET_SIZE];
+};
+
+static void ds_init(struct deferred_set *ds)
+{
+ int i;
+
+ spin_lock_init(&ds->lock);
+ ds->current_entry = 0;
+ ds->sweeper = 0;
+ for (i = 0; i < DEFERRED_SET_SIZE; i++) {
+ ds->entries[i].ds = ds;
+ ds->entries[i].count = 0;
+ INIT_LIST_HEAD(&ds->entries[i].work_items);
+ }
+}
+
+static struct deferred_entry *ds_inc(struct deferred_set *ds)
+{
+ unsigned long flags;
+ struct deferred_entry *entry;
+
+ spin_lock_irqsave(&ds->lock, flags);
+ entry = ds->entries + ds->current_entry;
+ entry->count++;
+ spin_unlock_irqrestore(&ds->lock, flags);
+
+ return entry;
+}
+
+static unsigned ds_next(unsigned index)
+{
+ return (index + 1) % DEFERRED_SET_SIZE;
+}
+
+static void __sweep(struct deferred_set *ds, struct list_head *head)
+{
+ while ((ds->sweeper != ds->current_entry) &&
+ !ds->entries[ds->sweeper].count) {
+ list_splice_init(&ds->entries[ds->sweeper].work_items, head);
+ ds->sweeper = ds_next(ds->sweeper);
+ }
+
+ if ((ds->sweeper == ds->current_entry) && !ds->entries[ds->sweeper].count)
+ list_splice_init(&ds->entries[ds->sweeper].work_items, head);
+}
+
+static void ds_dec(struct deferred_entry *entry, struct list_head *head)
+{
+ unsigned long flags;
+
+ spin_lock_irqsave(&entry->ds->lock, flags);
+ BUG_ON(!entry->count);
+ --entry->count;
+ __sweep(entry->ds, head);
+ spin_unlock_irqrestore(&entry->ds->lock, flags);
+}
+
+/*
+ * Returns 1 if deferred or 0 if no pending items to delay job.
+ */
+static int ds_add_work(struct deferred_set *ds, struct list_head *work)
+{
+ int r = 1;
+ unsigned long flags;
+ unsigned next_entry;
+
+ spin_lock_irqsave(&ds->lock, flags);
+ if ((ds->sweeper == ds->current_entry) &&
+ !ds->entries[ds->current_entry].count)
+ r = 0;
+ else {
+ list_add(work, &ds->entries[ds->current_entry].work_items);
+ next_entry = ds_next(ds->current_entry);
+ if (!ds->entries[next_entry].count)
+ ds->current_entry = next_entry;
+ }
+ spin_unlock_irqrestore(&ds->lock, flags);
+
+ return r;
+}
+
+/*----------------------------------------------------------------*/
+
+/*
+ * Key building.
+ */
+static void build_data_key(struct dm_thin_device *td,
+ dm_block_t b, struct cell_key *key)
+{
+ key->virtual = 0;
+ key->dev = dm_thin_dev_id(td);
+ key->block = b;
+}
+
+static void build_virtual_key(struct dm_thin_device *td, dm_block_t b,
+ struct cell_key *key)
+{
+ key->virtual = 1;
+ key->dev = dm_thin_dev_id(td);
+ key->block = b;
+}
+
+/*----------------------------------------------------------------*/
+
+struct new_mapping;
+
+/*
+ * A pool device ties together a metadata device and a data device. It
+ * also provides the interface for creating and destroying internal
+ * devices.
+ */
+struct pool {
+ struct list_head list;
+ struct dm_target *ti; /* Only set if a pool target is bound */
+
+ struct mapped_device *pool_md;
+ struct dm_pool_metadata *pmd;
+
+ uint32_t sectors_per_block;
+ unsigned block_shift;
+ dm_block_t offset_mask;
+ dm_block_t low_water_mark;
+ unsigned zero_new_blocks:1;
+
+ struct bio_prison *prison;
+ struct dm_kcopyd_client *copier;
+
+ struct workqueue_struct *wq;
+ struct work_struct worker;
+
+ spinlock_t lock;
+ struct bio_list deferred_bios;
+ struct list_head prepared_mappings;
+
+ int low_water_triggered; /* A dm event has been sent */
+ struct bio_list retry_list;
+
+ struct deferred_set ds; /* FIXME: move to thin_c */
+
+ struct new_mapping *next_mapping;
+
+ mempool_t *mapping_pool;
+ mempool_t *endio_hook_pool;
+
+ atomic_t ref_count;
+};
+
+/*
+ * Target context for a pool.
+ */
+struct pool_c {
+ struct dm_target *ti;
+ struct pool *pool;
+ struct dm_dev *data_dev;
+ struct dm_dev *metadata_dev;
+ struct dm_target_callbacks callbacks;
+
+ sector_t low_water_mark;
+ unsigned zero_new_blocks:1;
+};
+
+/*
+ * Target context for a thin.
+ */
+struct thin_c {
+ struct dm_dev *pool_dev;
+ dm_thin_id dev_id;
+
+ struct pool *pool;
+ struct dm_thin_device *td;
+};
+
+/*----------------------------------------------------------------*/
+
+/*
+ * A global list that uses a struct mapped_device as a key.
+ */
+static struct dm_thin_pool_table {
+ spinlock_t lock;
+ struct list_head pools;
+} dm_thin_pool_table;
+
+static void pool_table_init(void)
+{
+ spin_lock_init(&dm_thin_pool_table.lock);
+
+ INIT_LIST_HEAD(&dm_thin_pool_table.pools);
+}
+
+static void pool_table_insert(struct pool *pool)
+{
+ spin_lock(&dm_thin_pool_table.lock);
+ list_add(&pool->list, &dm_thin_pool_table.pools);
+ spin_unlock(&dm_thin_pool_table.lock);
+}
+
+static void pool_table_remove(struct pool *pool)
+{
+ spin_lock(&dm_thin_pool_table.lock);
+ list_del(&pool->list);
+ spin_unlock(&dm_thin_pool_table.lock);
+}
+
+static struct pool *pool_table_lookup(struct mapped_device *md)
+{
+ struct pool *pool = NULL, *tmp;
+
+ spin_lock(&dm_thin_pool_table.lock);
+ list_for_each_entry(tmp, &dm_thin_pool_table.pools, list)
+ if (tmp->pool_md == md) {
+ pool = tmp;
+ break;
+ }
+ spin_unlock(&dm_thin_pool_table.lock);
+
+ return pool;
+}
+
+/*----------------------------------------------------------------*/
+
+/*
+ * This section of code contains the logic for processing a thin device's IO.
+ * Much of the code depends on pool object resources (lists, workqueues, etc)
+ * but most is exclusively called from the thin target rather than the thin-pool
+ * target.
+ */
+
+static dm_block_t get_bio_block(struct thin_c *tc, struct bio *bio)
+{
+ return bio->bi_sector >> tc->pool->block_shift;
+}
+
+static void remap(struct thin_c *tc, struct bio *bio, dm_block_t block)
+{
+ struct pool *pool = tc->pool;
+
+ bio->bi_bdev = tc->pool_dev->bdev;
+ bio->bi_sector = (block << pool->block_shift) +
+ (bio->bi_sector & pool->offset_mask);
+}
+
+static void remap_and_issue(struct thin_c *tc, struct bio *bio,
+ dm_block_t block)
+{
+ if (bio->bi_rw & (REQ_FLUSH | REQ_FUA)) {
+ int r = dm_pool_commit_metadata(tc->pool->pmd);
+ if (r) {
+ DMERR("%s: dm_pool_commit_metadata() failed, error = %d",
+ __func__, r);
+ bio_io_error(bio);
+ return;
+ }
+ }
+
+ remap(tc, bio, block);
+ generic_make_request(bio);
+}
+
+/*
+ * wake_worker() is used by thin_defer_bio and pool_preresume to continue
+ * deferred IO processing after pool resume.
+ */
+static void wake_worker(struct pool *pool)
+{
+ queue_work(pool->wq, &pool->worker);
+}
+
+/*----------------------------------------------------------------*/
+
+/*
+ * Bio endio functions.
+ */
+
+struct endio_hook {
+ struct thin_c *tc;
+ bio_end_io_t *saved_bi_end_io;
+ struct deferred_entry *entry;
+};
+
+struct new_mapping {
+ struct list_head list;
+
+ int prepared;
+
+ struct thin_c *tc;
+ dm_block_t virt_block;
+ dm_block_t data_block;
+ struct cell *cell;
+ int err;
+
+ /*
+ * If the bio covers the whole area of a block then we can avoid
+ * zeroing or copying. Instead this bio is hooked. The bio will
+ * still be in the cell, so care has to be taken to avoid issuing
+ * the bio twice.
+ */
+ struct bio *bio;
+ bio_end_io_t *saved_bi_end_io;
+};
+
+static void __maybe_add_mapping(struct new_mapping *m)
+{
+ struct pool *pool = m->tc->pool;
+
+ if (list_empty(&m->list) && m->prepared) {
+ list_add(&m->list, &pool->prepared_mappings);
+ wake_worker(pool);
+ }
+}
+
+static void copy_complete(int read_err, unsigned long write_err, void *context)
+{
+ unsigned long flags;
+ struct new_mapping *m = context;
+ struct pool *pool = m->tc->pool;
+
+ m->err = read_err || write_err ? -EIO : 0;
+
+ spin_lock_irqsave(&pool->lock, flags);
+ m->prepared = 1;
+ __maybe_add_mapping(m);
+ spin_unlock_irqrestore(&pool->lock, flags);
+}
+
+static void overwrite_endio(struct bio *bio, int err)
+{
+ unsigned long flags;
+ struct new_mapping *m = dm_get_mapinfo(bio)->ptr;
+ struct pool *pool = m->tc->pool;
+
+ m->err = err;
+
+ spin_lock_irqsave(&pool->lock, flags);
+ m->prepared = 1;
+ __maybe_add_mapping(m);
+ spin_unlock_irqrestore(&pool->lock, flags);
+}
+
+static void shared_read_endio(struct bio *bio, int err)
+{
+ struct list_head mappings;
+ struct new_mapping *m, *tmp;
+ struct endio_hook *h = dm_get_mapinfo(bio)->ptr;
+ unsigned long flags;
+ struct pool *pool = h->tc->pool;
+
+ bio->bi_end_io = h->saved_bi_end_io;
+ bio_endio(bio, err);
+
+ INIT_LIST_HEAD(&mappings);
+ ds_dec(h->entry, &mappings);
+
+ spin_lock_irqsave(&pool->lock, flags);
+ list_for_each_entry_safe(m, tmp, &mappings, list) {
+ list_del(&m->list);
+ INIT_LIST_HEAD(&m->list);
+ __maybe_add_mapping(m);
+ }
+ spin_unlock_irqrestore(&pool->lock, flags);
+
+ mempool_free(h, pool->endio_hook_pool);
+}
+
+/*----------------------------------------------------------------*/
+
+/*
+ * Workqueue.
+ */
+
+/*
+ * Prepared mapping jobs.
+ */
+
+/*
+ * This sends the bios in the cell back to the deferred_bios list.
+ */
+static void cell_defer(struct thin_c *tc, struct cell *cell,
+ dm_block_t data_block)
+{
+ struct pool *pool = tc->pool;
+ unsigned long flags;
+
+ spin_lock_irqsave(&pool->lock, flags);
+ cell_release(cell, &pool->deferred_bios);
+ spin_unlock_irqrestore(&pool->lock, flags);
+
+ wake_worker(pool);
+}
+
+static void cell_defer_except(struct thin_c *tc, struct cell *cell,
+ struct bio *exception)
+{
+ struct bio_list bios;
+ struct bio *bio;
+ struct pool *pool = tc->pool;
+ unsigned long flags;
+
+ bio_list_init(&bios);
+ cell_release(cell, &bios);
+
+ spin_lock_irqsave(&pool->lock, flags);
+ while ((bio = bio_list_pop(&bios)))
+ if (bio != exception)
+ bio_list_add(&pool->deferred_bios, bio);
+ spin_unlock_irqrestore(&pool->lock, flags);
+
+ wake_worker(pool);
+}
+
+static void process_prepared_mapping(struct new_mapping *m)
+{
+ struct thin_c *tc = m->tc;
+ struct bio *bio;
+ int r;
+
+ bio = m->bio;
+ if (bio)
+ bio->bi_end_io = m->saved_bi_end_io;
+
+ if (m->err) {
+ cell_error(m->cell);
+ return;
+ }
+
+ r = dm_thin_insert_block(tc->td, m->virt_block, m->data_block);
+ if (r) {
+ DMERR("dm_thin_insert_block() failed");
+ cell_error(m->cell);
+ return;
+ }
+
+ if (bio) {
+ cell_defer_except(tc, m->cell, bio);
+ bio_endio(bio, 0);
+ } else
+ cell_defer(tc, m->cell, m->data_block);
+
+ mempool_free(m, tc->pool->mapping_pool);
+}
+
+static void process_prepared_mappings(struct pool *pool)
+{
+ unsigned long flags;
+ struct list_head maps;
+ struct new_mapping *m;
+
+ INIT_LIST_HEAD(&maps);
+ spin_lock_irqsave(&pool->lock, flags);
+ list_splice_init(&pool->prepared_mappings, &maps);
+ spin_unlock_irqrestore(&pool->lock, flags);
+
+ list_for_each_entry(m, &maps, list)
+ process_prepared_mapping(m);
+}
+
+/*
+ * Deferred bio jobs.
+ */
+static int io_overwrites_block(struct pool *pool, struct bio *bio)
+{
+ return ((bio_data_dir(bio) == WRITE) &&
+ (bio->bi_sector & pool->offset_mask) == 0) &&
+ (bio->bi_size == (pool->sectors_per_block << SECTOR_SHIFT));
+}
+
+static void save_and_set_endio(struct bio *bio, bio_end_io_t **save,
+ bio_end_io_t *fn)
+{
+ *save = bio->bi_end_io;
+ bio->bi_end_io = fn;
+}
+
+static int ensure_next_mapping(struct pool *pool)
+{
+ if (pool->next_mapping)
+ return 0;
+
+ pool->next_mapping = mempool_alloc(pool->mapping_pool, GFP_ATOMIC);
+
+ return pool->next_mapping ? 0 : -ENOMEM;
+}
+
+static struct new_mapping *get_next_mapping(struct pool *pool)
+{
+ struct new_mapping *r = pool->next_mapping;
+
+ BUG_ON(!pool->next_mapping);
+
+ pool->next_mapping = NULL;
+
+ return r;
+}
+
+static void schedule_copy(struct thin_c *tc, dm_block_t virt_block,
+ dm_block_t data_origin, dm_block_t data_dest,
+ struct cell *cell, struct bio *bio)
+{
+ int r;
+ struct pool *pool = tc->pool;
+ struct new_mapping *m = get_next_mapping(pool);
+
+ INIT_LIST_HEAD(&m->list);
+ m->prepared = 0;
+ m->tc = tc;
+ m->virt_block = virt_block;
+ m->data_block = data_dest;
+ m->cell = cell;
+ m->err = 0;
+ m->bio = NULL;
+
+ ds_add_work(&pool->ds, &m->list);
+
+ /*
+ * IO to pool_dev remaps to the pool target's data_dev.
+ *
+ * If the whole block of data is being overwritten, we can issue the
+ * bio immediately. Otherwise we use kcopyd to clone the data first.
+ */
+ if (io_overwrites_block(pool, bio)) {
+ m->bio = bio;
+ save_and_set_endio(bio, &m->saved_bi_end_io, overwrite_endio);
+ dm_get_mapinfo(bio)->ptr = m;
+ remap_and_issue(tc, bio, data_dest);
+ } else {
+ struct dm_io_region from, to;
+
+ from.bdev = tc->pool_dev->bdev;
+ from.sector = data_origin * pool->sectors_per_block;
+ from.count = pool->sectors_per_block;
+
+ to.bdev = tc->pool_dev->bdev;
+ to.sector = data_dest * pool->sectors_per_block;
+ to.count = pool->sectors_per_block;
+
+ r = dm_kcopyd_copy(pool->copier, &from, 1, &to,
+ 0, copy_complete, m);
+ if (r < 0) {
+ mempool_free(m, pool->mapping_pool);
+ DMERR("dm_kcopyd_copy() failed");
+ cell_error(cell);
+ }
+ }
+}
+
+static void schedule_zero(struct thin_c *tc, dm_block_t virt_block,
+ dm_block_t data_block, struct cell *cell,
+ struct bio *bio)
+{
+ struct pool *pool = tc->pool;
+ struct new_mapping *m = get_next_mapping(pool);
+
+ INIT_LIST_HEAD(&m->list);
+ m->prepared = 0;
+ m->tc = tc;
+ m->virt_block = virt_block;
+ m->data_block = data_block;
+ m->cell = cell;
+ m->err = 0;
+ m->bio = NULL;
+
+ /*
+ * If the whole block of data is being overwritten or we are not
+ * zeroing pre-existing data, we can issue the bio immediately.
+ * Otherwise we use kcopyd to zero the data first.
+ */
+ if (!pool->zero_new_blocks)
+ process_prepared_mapping(m);
+ else if (io_overwrites_block(pool, bio)) {
+ m->bio = bio;
+ save_and_set_endio(bio, &m->saved_bi_end_io, overwrite_endio);
+ dm_get_mapinfo(bio)->ptr = m;
+ remap_and_issue(tc, bio, data_block);
+ } else {
+ int r;
+ struct dm_io_region to;
+
+ to.bdev = tc->pool_dev->bdev;
+ to.sector = data_block * pool->sectors_per_block;
+ to.count = pool->sectors_per_block;
+
+ r = dm_kcopyd_zero(pool->copier, 1, &to, 0, copy_complete, m);
+ if (r < 0) {
+ mempool_free(m, pool->mapping_pool);
+ DMERR("dm_kcopyd_zero() failed");
+ cell_error(cell);
+ }
+ }
+}
+
+static void retry_later(struct bio *bio)
+{
+ struct thin_c *tc = dm_get_mapinfo(bio)->ptr;
+ struct pool *pool = tc->pool;
+ unsigned long flags;
+
+ spin_lock_irqsave(&pool->lock, flags);
+ bio_list_add(&pool->retry_list, bio);
+ spin_unlock_irqrestore(&pool->lock, flags);
+}
+
+static int alloc_data_block(struct thin_c *tc, dm_block_t *result)
+{
+ int r;
+ dm_block_t free_blocks;
+ unsigned long flags;
+ struct pool *pool = tc->pool;
+
+ r = dm_pool_get_free_block_count(pool->pmd, &free_blocks);
+ if (r)
+ return r;
+
+ if (free_blocks <= pool->low_water_mark && !pool->low_water_triggered) {
+ spin_lock_irqsave(&pool->lock, flags);
+ pool->low_water_triggered = 1;
+ spin_unlock_irqrestore(&pool->lock, flags);
+ dm_table_event(pool->ti->table);
+ }
+
+ r = dm_pool_alloc_data_block(pool->pmd, result);
+ if (r)
+ return r;
+
+ return 0;
+}
+
+static void no_space(struct cell *cell)
+{
+ struct bio *bio;
+ struct bio_list bios;
+
+ bio_list_init(&bios);
+ cell_release(cell, &bios);
+
+ while ((bio = bio_list_pop(&bios)))
+ retry_later(bio);
+}
+
+static void break_sharing(struct thin_c *tc, struct bio *bio, dm_block_t block,
+ struct cell_key *key,
+ struct dm_thin_lookup_result *lookup_result,
+ struct cell *cell)
+{
+ int r;
+ dm_block_t data_block;
+
+ r = alloc_data_block(tc, &data_block);
+ switch (r) {
+ case 0:
+ schedule_copy(tc, block, lookup_result->block,
+ data_block, cell, bio);
+ break;
+
+ case -ENOSPC:
+ no_space(cell);
+ break;
+
+ default:
+ DMERR("%s: alloc_data_block() failed, error = %d", __func__, r);
+ cell_error(cell);
+ break;
+ }
+}
+
+static void process_shared_bio(struct thin_c *tc, struct bio *bio,
+ dm_block_t block,
+ struct dm_thin_lookup_result *lookup_result)
+{
+ struct cell *cell;
+ struct cell_key key;
+ struct pool *pool = tc->pool;
+
+ /*
+ * If cell is already occupied, then sharing is already in the process
+ * of being broken so we have nothing further to do here.
+ */
+ build_data_key(tc->td, lookup_result->block, &key);
+ if (bio_detain(pool->prison, &key, bio, &cell))
+ return;
+
+ if (bio_data_dir(bio) == WRITE)
+ break_sharing(tc, bio, block, &key, lookup_result, cell);
+ else {
+ struct endio_hook *h;
+ h = mempool_alloc(pool->endio_hook_pool, GFP_NOIO);
+
+ h->tc = tc;
+ h->entry = ds_inc(&pool->ds);
+ save_and_set_endio(bio, &h->saved_bi_end_io, shared_read_endio);
+ dm_get_mapinfo(bio)->ptr = h;
+
+ cell_release_singleton(cell, bio);
+ remap_and_issue(tc, bio, lookup_result->block);
+ }
+}
+
+static void provision_block(struct thin_c *tc, struct bio *bio, dm_block_t block,
+ struct cell *cell)
+{
+ int r;
+ dm_block_t data_block;
+
+ r = alloc_data_block(tc, &data_block);
+ switch (r) {
+ case 0:
+ schedule_zero(tc, block, data_block, cell, bio);
+ break;
+
+ case -ENOSPC:
+ no_space(cell);
+ break;
+
+ default:
+ DMERR("%s: alloc_data_block() failed, error = %d", __func__, r);
+ cell_error(cell);
+ break;
+ }
+}
+
+static void process_bio(struct thin_c *tc, struct bio *bio)
+{
+ int r;
+ dm_block_t block = get_bio_block(tc, bio);
+ struct cell *cell;
+ struct cell_key key;
+ struct dm_thin_lookup_result lookup_result;
+
+ /*
+ * If cell is already occupied, then the block is already
+ * being provisioned so we have nothing further to do here.
+ */
+ build_virtual_key(tc->td, block, &key);
+ if (bio_detain(tc->pool->prison, &key, bio, &cell))
+ return;
+
+ r = dm_thin_find_block(tc->td, block, 1, &lookup_result);
+ switch (r) {
+ case 0:
+ /*
+ * We can release this cell now. This thread is the only
+ * one that puts bios into a cell, and we know there were
+ * no preceeding bios.
+ */
+ cell_release_singleton(cell, bio);
+
+ if (lookup_result.shared)
+ process_shared_bio(tc, bio, block, &lookup_result);
+ else
+ remap_and_issue(tc, bio, lookup_result.block);
+ break;
+
+ case -ENODATA:
+ provision_block(tc, bio, block, cell);
+ break;
+
+ default:
+ DMERR("dm_thin_find_block() failed, error = %d", r);
+ bio_io_error(bio);
+ break;
+ }
+}
+
+static void process_deferred_bios(struct pool *pool)
+{
+ unsigned long flags;
+ struct bio *bio;
+ struct bio_list bios;
+
+ bio_list_init(&bios);
+
+ spin_lock_irqsave(&pool->lock, flags);
+ bio_list_merge(&bios, &pool->deferred_bios);
+ bio_list_init(&pool->deferred_bios);
+ spin_unlock_irqrestore(&pool->lock, flags);
+
+ while ((bio = bio_list_pop(&bios))) {
+ struct thin_c *tc = dm_get_mapinfo(bio)->ptr;
+
+ /*
+ * If we've got no free new_mapping structs, and processing this bio
+ * might require one, we pause until there are some prepared mappings to
+ * process.
+ */
+ if (ensure_next_mapping(pool)) {
+ spin_lock_irqsave(&pool->lock, flags);
+ bio_list_merge(&pool->deferred_bios, &bios);
+ spin_unlock_irqrestore(&pool->lock, flags);
+
+ return;
+ }
+
+ process_bio(tc, bio);
+ }
+}
+
+static void do_worker(struct work_struct *ws)
+{
+ struct pool *pool = container_of(ws, struct pool, worker);
+
+ process_prepared_mappings(pool);
+ process_deferred_bios(pool);
+}
+
+/*----------------------------------------------------------------*/
+
+/*
+ * Mapping functions.
+ */
+
+/*
+ * Called only while mapping a thin bio to hand it over to the producer queue.
+ */
+static void thin_defer_bio(struct thin_c *tc, struct bio *bio)
+{
+ unsigned long flags;
+ struct pool *pool = tc->pool;
+
+ spin_lock_irqsave(&pool->lock, flags);
+ bio_list_add(&pool->deferred_bios, bio);
+ spin_unlock_irqrestore(&pool->lock, flags);
+
+ wake_worker(pool);
+}
+
+/*
+ * Non-blocking function designed to be called from the target's map
+ * function.
+ */
+static int thin_bio_map(struct dm_target *ti, struct bio *bio,
+ union map_info *map_context)
+{
+ int r;
+ struct thin_c *tc = ti->private;
+ dm_block_t block = get_bio_block(tc, bio);
+ struct dm_thin_device *td = tc->td;
+ struct dm_thin_lookup_result result;
+
+ /*
+ * Save the thin context for easy access from the deferred bio later.
+ */
+ map_context->ptr = tc;
+
+ if (bio->bi_rw & (REQ_FLUSH | REQ_FUA)) {
+ thin_defer_bio(tc, bio);
+ return DM_MAPIO_SUBMITTED;
+ }
+
+ r = dm_thin_find_block(td, block, 0, &result);
+
+ /*
+ * Note that we defer readahead too.
+ */
+ switch (r) {
+ case 0:
+ if (unlikely(result.shared)) {
+ /*
+ * We have a race condition here between the
+ * result.shared value returned by the lookup and
+ * snapshot creation, which may cause new
+ * sharing.
+ *
+ * To avoid this always quiesce the origin before
+ * taking the snap. You want to do this anyway to
+ * ensure a consistent application view
+ * (i.e. lockfs).
+ *
+ * More distant ancestors are irrelevant: the
+ * shared flag will be set in their case.
+ */
+ thin_defer_bio(tc, bio);
+ r = DM_MAPIO_SUBMITTED;
+ } else {
+ remap(tc, bio, result.block);
+ r = DM_MAPIO_REMAPPED;
+ }
+ break;
+
+ case -ENODATA:
+ /*
+ * In future, the failed dm_thin_find_block above could
+ * provide the hint to load the metadata into cache.
+ */
+ case -EWOULDBLOCK:
+ thin_defer_bio(tc, bio);
+ r = DM_MAPIO_SUBMITTED;
+ break;
+ }
+
+ return r;
+}
+
+static int pool_map(struct dm_target *ti, struct bio *bio,
+ union map_info *map_context)
+{
+ int r;
+ struct pool_c *pt = ti->private;
+ struct pool *pool = pt->pool;
+ unsigned long flags;
+
+ spin_lock_irqsave(&pool->lock, flags);
+ bio->bi_bdev = pt->data_dev->bdev;
+ r = DM_MAPIO_REMAPPED;
+ spin_unlock_irqrestore(&pool->lock, flags);
+
+ return r;
+}
+
+/*----------------------------------------------------------------
+ * Binding of control targets to a pool object
+ *--------------------------------------------------------------*/
+/* FIXME: add locking */
+static int bind_control_target(struct pool *pool, struct dm_target *ti)
+{
+ struct pool_c *pt = ti->private;
+
+ pool->ti = ti;
+ pool->low_water_mark = dm_sector_div_up(pt->low_water_mark,
+ pool->sectors_per_block);
+ pool->zero_new_blocks = pt->zero_new_blocks;
+ dm_pool_rebind_metadata_device(pool->pmd, pt->metadata_dev->bdev);
+
+ return 0;
+}
+
+static void unbind_control_target(struct pool *pool, struct dm_target *ti)
+{
+ if (pool->ti == ti)
+ pool->ti = NULL;
+}
+
+/*----------------------------------------------------------------
+ * Pool creation
+ *--------------------------------------------------------------*/
+static void pool_destroy(struct pool *pool)
+{
+ if (dm_pool_metadata_close(pool->pmd) < 0)
+ DMWARN("%s: dm_pool_metadata_close() failed.", __func__);
+
+ prison_destroy(pool->prison);
+ dm_kcopyd_client_destroy(pool->copier);
+
+ if (pool->wq)
+ destroy_workqueue(pool->wq);
+
+ mempool_destroy(pool->mapping_pool);
+ mempool_destroy(pool->endio_hook_pool);
+ kfree(pool);
+}
+
+static struct pool *pool_create(struct block_device *metadata_dev,
+ unsigned long block_size, char **error)
+{
+ int r;
+ void *err_p;
+ struct pool *pool;
+ struct dm_pool_metadata *pmd;
+
+ pmd = dm_pool_metadata_open(metadata_dev, block_size);
+ if (IS_ERR(pmd)) {
+ *error = "Error creating metadata object";
+ return (struct pool *)pmd;
+ }
+
+ pool = kmalloc(sizeof(*pool), GFP_KERNEL);
+ if (!pool) {
+ *error = "Error allocating memory for pool";
+ err_p = ERR_PTR(-ENOMEM);
+ goto bad_pool;
+ }
+
+ pool->pmd = pmd;
+ pool->sectors_per_block = block_size;
+ pool->block_shift = ffs(block_size) - 1;
+ pool->offset_mask = block_size - 1;
+ pool->low_water_mark = 0;
+ pool->zero_new_blocks = 1;
+ pool->prison = prison_create(PRISON_CELLS);
+ if (!pool->prison) {
+ *error = "Error creating pool's bio prison";
+ err_p = ERR_PTR(-ENOMEM);
+ goto bad_prison;
+ }
+
+ pool->copier = dm_kcopyd_client_create();
+ if (IS_ERR(pool->copier)) {
+ r = PTR_ERR(pool->copier);
+ *error = "Error creating pool's kcopyd client";
+ err_p = ERR_PTR(r);
+ goto bad_kcopyd_client;
+ }
+
+ /*
+ * Create singlethreaded workqueue that will service all devices
+ * that use this metadata.
+ */
+ pool->wq = alloc_ordered_workqueue("dm-" DM_MSG_PREFIX, WQ_MEM_RECLAIM);
+ if (!pool->wq) {
+ *error = "Error creating pool's workqueue";
+ err_p = ERR_PTR(-ENOMEM);
+ goto bad_wq;
+ }
+
+ INIT_WORK(&pool->worker, do_worker);
+ spin_lock_init(&pool->lock);
+ bio_list_init(&pool->deferred_bios);
+ INIT_LIST_HEAD(&pool->prepared_mappings);
+ pool->low_water_triggered = 0;
+ bio_list_init(&pool->retry_list);
+ ds_init(&pool->ds);
+
+ pool->next_mapping = NULL;
+ pool->mapping_pool =
+ mempool_create_kmalloc_pool(MAPPING_POOL_SIZE, sizeof(struct new_mapping));
+ if (!pool->mapping_pool) {
+ *error = "Error creating pool's mapping mempool";
+ err_p = ERR_PTR(-ENOMEM);
+ goto bad_mapping_pool;
+ }
+
+ pool->endio_hook_pool =
+ mempool_create_kmalloc_pool(ENDIO_HOOK_POOL_SIZE, sizeof(struct endio_hook));
+ if (!pool->endio_hook_pool) {
+ *error = "Error creating pool's endio_hook mempool";
+ err_p = ERR_PTR(-ENOMEM);
+ goto bad_endio_hook_pool;
+ }
+ atomic_set(&pool->ref_count, 1);
+
+ return pool;
+
+bad_endio_hook_pool:
+ mempool_destroy(pool->mapping_pool);
+bad_mapping_pool:
+ destroy_workqueue(pool->wq);
+bad_wq:
+ dm_kcopyd_client_destroy(pool->copier);
+bad_kcopyd_client:
+ prison_destroy(pool->prison);
+bad_prison:
+ kfree(pool);
+bad_pool:
+ if (dm_pool_metadata_close(pmd))
+ DMWARN("%s: dm_pool_metadata_close() failed.", __func__);
+
+ return err_p;
+}
+
+static void pool_inc(struct pool *pool)
+{
+ atomic_inc(&pool->ref_count);
+}
+
+static void pool_dec(struct pool *pool)
+{
+ if (atomic_dec_and_test(&pool->ref_count))
+ pool_destroy(pool);
+}
+
+static struct pool *pool_find(struct mapped_device *pool_md,
+ struct block_device *metadata_dev,
+ unsigned long block_size,
+ char **error)
+{
+ struct pool *pool;
+
+ pool = pool_table_lookup(pool_md);
+ if (pool)
+ pool_inc(pool);
+ else
+ pool = pool_create(metadata_dev, block_size, error);
+
+ return pool;
+}
+
+/*----------------------------------------------------------------
+ * Pool target methods
+ *--------------------------------------------------------------*/
+struct pool_features {
+ unsigned zero_new_blocks:1;
+};
+
+static int parse_pool_features(struct dm_arg_set *as, struct pool_features *pf,
+ struct dm_target *ti)
+{
+ int r;
+ unsigned argc;
+ const char *arg_name;
+
+ static struct dm_arg _args[] = {
+ {0, 1, "Invalid number of pool feature arguments"},
+ };
+
+ /*
+ * No feature arguments supplied.
+ */
+ if (!as->argc)
+ return 0;
+
+ r = dm_read_arg_group(_args, as, &argc, &ti->error);
+ if (r)
+ return -EINVAL;
+
+ while (argc && !r) {
+ arg_name = dm_shift_arg(as);
+ argc--;
+
+ if (!strcasecmp(arg_name, "skip_block_zeroing")) {
+ pf->zero_new_blocks = 0;
+ continue;
+ }
+
+ ti->error = "Unrecognised pool feature requested";
+ r = -EINVAL;
+ }
+
+ return r;
+}
+
+static int pool_is_congested(struct dm_target_callbacks *cb, int bdi_bits)
+{
+ int r;
+ unsigned long flags;
+ struct pool_c *pt = container_of(cb, struct pool_c, callbacks);
+
+ spin_lock_irqsave(&pt->pool->lock, flags);
+ r = !bio_list_empty(&pt->pool->retry_list);
+ spin_unlock_irqrestore(&pt->pool->lock, flags);
+
+ if (!r) {
+ struct request_queue *q = bdev_get_queue(pt->data_dev->bdev);
+ r = bdi_congested(&q->backing_dev_info, bdi_bits);
+ }
+
+ return r;
+}
+
+/*
+ * thin-pool <metadata dev> <data dev>
+ * <data block size (sectors)>
+ * <low water mark (sectors)>
+ * [<#feature args> [<arg>]*]
+ *
+ * Optional feature arguments are:
+ * skip_block_zeroing: skips the zeroing of newly-provisioned blocks.
+ */
+static int pool_ctr(struct dm_target *ti, unsigned argc, char **argv)
+{
+ int r;
+ struct pool_c *pt;
+ struct pool *pool;
+ struct pool_features pf;
+ struct dm_arg_set as;
+ struct dm_dev *data_dev;
+ unsigned long block_size;
+ dm_block_t low_water;
+ struct dm_dev *metadata_dev;
+ sector_t metadata_dev_size;
+
+ if (argc < 4) {
+ ti->error = "Invalid argument count";
+ return -EINVAL;
+ }
+ as.argc = argc;
+ as.argv = argv;
+
+ r = dm_get_device(ti, argv[0], FMODE_READ | FMODE_WRITE, &metadata_dev);
+ if (r) {
+ ti->error = "Error opening metadata block device";
+ return r;
+ }
+
+ metadata_dev_size = i_size_read(metadata_dev->bdev->bd_inode) >> SECTOR_SHIFT;
+ if (metadata_dev_size > METADATA_DEV_MAX_SECTORS) {
+ ti->error = "Metadata device is too large";
+ r = -EINVAL;
+ goto out_metadata;
+ }
+
+ r = dm_get_device(ti, argv[1], FMODE_READ | FMODE_WRITE, &data_dev);
+ if (r) {
+ ti->error = "Error getting data device";
+ goto out_metadata;
+ }
+
+ if (kstrtoul(argv[2], 10, &block_size) || !block_size ||
+ block_size < DATA_DEV_BLOCK_SIZE_MIN_SECTORS ||
+ block_size > DATA_DEV_BLOCK_SIZE_MAX_SECTORS ||
+ !is_power_of_2(block_size)) {
+ ti->error = "Invalid block size";
+ r = -EINVAL;
+ goto out;
+ }
+
+ if (kstrtoull(argv[3], 10, (unsigned long long *)&low_water) ||
+ !low_water) {
+ ti->error = "Invalid low water mark";
+ r = -EINVAL;
+ goto out;
+ }
+
+ /*
+ * Set default pool features.
+ */
+ memset(&pf, 0, sizeof(pf));
+ pf.zero_new_blocks = 1;
+
+ dm_consume_args(&as, 4);
+ r = parse_pool_features(&as, &pf, ti);
+ if (r)
+ goto out;
+
+ pool = pool_find(dm_table_get_md(ti->table), metadata_dev->bdev,
+ block_size, &ti->error);
+ if (IS_ERR(pool)) {
+ r = PTR_ERR(pool);
+ goto out;
+ }
+
+ pt = kzalloc(sizeof(*pt), GFP_KERNEL);
+ if (!pt) {
+ pool_destroy(pool);
+ r = -ENOMEM;
+ goto out;
+ }
+ pt->pool = pool;
+ pt->ti = ti;
+ pt->metadata_dev = metadata_dev;
+ pt->data_dev = data_dev;
+ pt->low_water_mark = low_water;
+ pt->zero_new_blocks = pf.zero_new_blocks;
+ ti->num_flush_requests = 1;
+ ti->num_discard_requests = 0;
+ ti->discards_supported = 0;
+ ti->private = pt;
+
+ pt->callbacks.congested_fn = pool_is_congested;
+ dm_table_add_target_callbacks(ti->table, &pt->callbacks);
+
+ return 0;
+
+out:
+ dm_put_device(ti, data_dev);
+out_metadata:
+ dm_put_device(ti, metadata_dev);
+
+ return r;
+}
+
+static void pool_dtr(struct dm_target *ti)
+{
+ struct pool_c *pt = ti->private;
+
+ dm_put_device(ti, pt->metadata_dev);
+ dm_put_device(ti, pt->data_dev);
+ unbind_control_target(pt->pool, ti);
+ pool_dec(pt->pool);
+ kfree(pt);
+}
+
+static void __requeue_bios(struct pool *pool)
+{
+ bio_list_merge(&pool->deferred_bios, &pool->retry_list);
+ bio_list_init(&pool->retry_list);
+}
+
+/*
+ * Retrieves the number of blocks of the data device from
+ * the superblock and compares it to the actual device size,
+ * thus resizing the data device in case it has grown.
+ *
+ * This both copes with opening preallocated data devices in the ctr
+ * being followed by a resume
+ * -and-
+ * calling the resume method individually after userspace has
+ * grown the data device in reaction to a table event.
+ */
+static int pool_preresume(struct dm_target *ti)
+{
+ int r;
+ struct pool_c *pt = ti->private;
+ struct pool *pool = pt->pool;
+ dm_block_t data_size, sb_data_size;
+ unsigned long flags;
+
+ /*
+ * Take control of the pool object.
+ */
+ r = bind_control_target(pool, ti);
+ if (r)
+ return r;
+
+ data_size = ti->len >> pool->block_shift;
+ r = dm_pool_get_data_dev_size(pool->pmd, &sb_data_size);
+ if (r) {
+ DMERR("failed to retrieve data device size");
+ return r;
+ }
+
+ if (data_size < sb_data_size) {
+ DMERR("pool target too small, is %llu blocks (expected %llu)",
+ data_size, sb_data_size);
+ return -EINVAL;
+
+ } else if (data_size > sb_data_size) {
+ r = dm_pool_resize_data_dev(pool->pmd, data_size);
+ if (r) {
+ DMERR("failed to resize data device");
+ return r;
+ }
+
+ r = dm_pool_commit_metadata(pool->pmd);
+ if (r) {
+ DMERR("%s: dm_pool_commit_metadata() failed, error = %d",
+ __func__, r);
+ return r;
+ }
+ }
+
+ spin_lock_irqsave(&pool->lock, flags);
+ pool->low_water_triggered = 0;
+ __requeue_bios(pool);
+ spin_unlock_irqrestore(&pool->lock, flags);
+
+ wake_worker(pool);
+
+ /*
+ * The pool object is only present if the pool is active.
+ */
+ pool->pool_md = dm_table_get_md(ti->table);
+ pool_table_insert(pool);
+
+ return 0;
+}
+
+static void pool_postsuspend(struct dm_target *ti)
+{
+ int r;
+ struct pool_c *pt = ti->private;
+ struct pool *pool = pt->pool;
+
+ flush_workqueue(pool->wq);
+
+ r = dm_pool_commit_metadata(pool->pmd);
+ if (r < 0) {
+ DMERR("%s: dm_pool_commit_metadata() failed, error = %d",
+ __func__, r);
+ /* FIXME: invalidate device? error the next FUA or FLUSH bio ?*/
+ }
+
+ pool_table_remove(pool);
+ pool->pool_md = NULL;
+}
+
+static int check_arg_count(unsigned argc, unsigned args_required)
+{
+ if (argc != args_required) {
+ DMWARN("Message received with %u arguments instead of %u.",
+ argc, args_required);
+ return -EINVAL;
+ }
+
+ return 0;
+}
+
+static int read_dev_id(char *arg, dm_thin_id *dev_id, int warning)
+{
+ if (!kstrtoull(arg, 10, (unsigned long long *)dev_id) &&
+ *dev_id <= MAX_DEV_ID)
+ return 0;
+
+ if (warning)
+ DMWARN("Message received with invalid device id: %s", arg);
+
+ return -EINVAL;
+}
+
+static int process_create_thin_mesg(unsigned argc, char **argv, struct pool *pool)
+{
+ dm_thin_id dev_id;
+ int r;
+
+ r = check_arg_count(argc, 2);
+ if (r)
+ return r;
+
+ r = read_dev_id(argv[1], &dev_id, 1);
+ if (r)
+ return r;
+
+ r = dm_pool_create_thin(pool->pmd, dev_id);
+ if (r) {
+ DMWARN("Creation of new thinly-provisioned device with id %s failed.",
+ argv[1]);
+ return r;
+ }
+
+ return 0;
+}
+
+static int process_create_snap_mesg(unsigned argc, char **argv, struct pool *pool)
+{
+ dm_thin_id dev_id;
+ dm_thin_id origin_dev_id;
+ int r;
+
+ r = check_arg_count(argc, 3);
+ if (r)
+ return r;
+
+ r = read_dev_id(argv[1], &dev_id, 1);
+ if (r)
+ return r;
+
+ r = read_dev_id(argv[2], &origin_dev_id, 1);
+ if (r)
+ return r;
+
+ r = dm_pool_create_snap(pool->pmd, dev_id, origin_dev_id);
+ if (r) {
+ DMWARN("Creation of new snapshot %s of device %s failed.",
+ argv[1], argv[2]);
+ return r;
+ }
+
+ return 0;
+}
+
+static int process_delete_mesg(unsigned argc, char **argv, struct pool *pool)
+{
+ dm_thin_id dev_id;
+ int r;
+
+ r = check_arg_count(argc, 2);
+ if (r)
+ return r;
+
+ r = read_dev_id(argv[1], &dev_id, 1);
+ if (r)
+ return r;
+
+ r = dm_pool_delete_thin_device(pool->pmd, dev_id);
+ if (r)
+ DMWARN("Deletion of thin device %s failed.", argv[1]);
+
+ return r;
+}
+
+static int process_trim_mesg(unsigned argc, char **argv, struct pool *pool)
+{
+ dm_thin_id dev_id;
+ sector_t new_size;
+ int r;
+
+ r = check_arg_count(argc, 3);
+ if (r)
+ return r;
+
+ r = read_dev_id(argv[1], &dev_id, 1);
+ if (r)
+ return r;
+
+ if (kstrtoull(argv[2], 10, (unsigned long long *)&new_size)) {
+ DMWARN("trim device %s: Invalid new size: %s sectors.",
+ argv[1], argv[2]);
+ return -EINVAL;
+ }
+
+ r = dm_pool_trim_thin_device(pool->pmd, dev_id,
+ dm_sector_div_up(new_size, pool->sectors_per_block));
+ if (r)
+ DMWARN("Attempt to trim thin device %s failed.", argv[1]);
+
+ return r;
+}
+
+static int process_set_transaction_id_mesg(unsigned argc, char **argv, struct pool *pool)
+{
+ dm_thin_id old_id, new_id;
+ int r;
+
+ r = check_arg_count(argc, 3);
+ if (r)
+ return r;
+
+ if (kstrtoull(argv[1], 10, (unsigned long long *)&old_id)) {
+ DMWARN("set_transaction_id message: Unrecognised id %s.", argv[1]);
+ return -EINVAL;
+ }
+
+ if (kstrtoull(argv[2], 10, (unsigned long long *)&new_id)) {
+ DMWARN("set_transaction_id message: Unrecognised new id %s.", argv[2]);
+ return -EINVAL;
+ }
+
+ r = dm_pool_set_metadata_transaction_id(pool->pmd, old_id, new_id);
+ if (r) {
+ DMWARN("Failed to change transaction id from %s to %s.",
+ argv[1], argv[2]);
+ return r;
+ }
+
+ return 0;
+}
+
+/*
+ * Messages supported:
+ * create_thin <dev_id>
+ * create_snap <dev_id> <origin_id>
+ * delete <dev_id>
+ * trim <dev_id> <new_size_in_sectors>
+ * set_transaction_id <current_trans_id> <new_trans_id>
+ */
+static int pool_message(struct dm_target *ti, unsigned argc, char **argv)
+{
+ int r = -EINVAL;
+ struct pool_c *pt = ti->private;
+ struct pool *pool = pt->pool;
+
+ if (!strcasecmp(argv[0], "create_thin"))
+ r = process_create_thin_mesg(argc, argv, pool);
+
+ else if (!strcasecmp(argv[0], "create_snap"))
+ r = process_create_snap_mesg(argc, argv, pool);
+
+ else if (!strcasecmp(argv[0], "delete"))
+ r = process_delete_mesg(argc, argv, pool);
+
+ else if (!strcasecmp(argv[0], "trim"))
+ r = process_trim_mesg(argc, argv, pool);
+
+ else if (!strcasecmp(argv[0], "set_transaction_id"))
+ r = process_set_transaction_id_mesg(argc, argv, pool);
+
+ else
+ DMWARN("Unrecognised thin pool target message received: %s", argv[0]);
+
+ if (!r) {
+ r = dm_pool_commit_metadata(pool->pmd);
+ if (r)
+ DMERR("%s message: dm_pool_commit_metadata() failed, error = %d",
+ argv[0], r);
+ }
+
+ return r;
+}
+
+/*
+ * Status line is:
+ * <transaction id> <free metadata space in sectors>
+ * <free data space in sectors> <held metadata root>
+ */
+static int pool_status(struct dm_target *ti, status_type_t type,
+ char *result, unsigned maxlen)
+{
+ int r;
+ unsigned sz = 0;
+ uint64_t transaction_id;
+ dm_block_t nr_free_blocks_data;
+ dm_block_t nr_free_blocks_metadata;
+ dm_block_t held_root;
+ char buf[BDEVNAME_SIZE];
+ char buf2[BDEVNAME_SIZE];
+ struct pool_c *pt = ti->private;
+ struct pool *pool = pt->pool;
+
+ switch (type) {
+ case STATUSTYPE_INFO:
+ r = dm_pool_get_metadata_transaction_id(pool->pmd,
+ &transaction_id);
+ if (r)
+ return r;
+
+ r = dm_pool_get_free_metadata_block_count(pool->pmd,
+ &nr_free_blocks_metadata);
+ if (r)
+ return r;
+
+ r = dm_pool_get_free_block_count(pool->pmd,
+ &nr_free_blocks_data);
+ if (r)
+ return r;
+
+ r = dm_pool_get_held_metadata_root(pool->pmd, &held_root);
+ if (r)
+ return r;
+
+ DMEMIT("%llu %llu %llu ", (unsigned long long)transaction_id,
+ (unsigned long long)nr_free_blocks_metadata * pool->sectors_per_block,
+ (unsigned long long)nr_free_blocks_data * pool->sectors_per_block);
+
+ if (held_root)
+ DMEMIT("%llu", held_root);
+ else
+ DMEMIT("-");
+
+ break;
+
+ case STATUSTYPE_TABLE:
+ DMEMIT("%s %s %lu %llu ",
+ format_dev_t(buf, pt->metadata_dev->bdev->bd_dev),
+ format_dev_t(buf2, pt->data_dev->bdev->bd_dev),
+ (unsigned long)pool->sectors_per_block,
+ (unsigned long long)pt->low_water_mark);
+
+ DMEMIT("%u ", !pool->zero_new_blocks);
+
+ if (!pool->zero_new_blocks)
+ DMEMIT("skip_block_zeroing ");
+ break;
+ }
+
+ return 0;
+}
+
+static int pool_iterate_devices(struct dm_target *ti,
+ iterate_devices_callout_fn fn, void *data)
+{
+ struct pool_c *pt = ti->private;
+
+ return fn(ti, pt->data_dev, 0, ti->len, data);
+}
+
+static int pool_merge(struct dm_target *ti, struct bvec_merge_data *bvm,
+ struct bio_vec *biovec, int max_size)
+{
+ struct pool_c *pt = ti->private;
+ struct request_queue *q = bdev_get_queue(pt->data_dev->bdev);
+
+ if (!q->merge_bvec_fn)
+ return max_size;
+
+ bvm->bi_bdev = pt->data_dev->bdev;
+
+ return min(max_size, q->merge_bvec_fn(q, bvm, biovec));
+}
+
+static void pool_io_hints(struct dm_target *ti, struct queue_limits *limits)
+{
+ struct pool_c *pt = ti->private;
+ struct pool *pool = pt->pool;
+
+ blk_limits_io_min(limits, 0);
+ blk_limits_io_opt(limits, pool->sectors_per_block << SECTOR_SHIFT);
+}
+
+static struct target_type pool_target = {
+ .name = "thin-pool",
+ .features = DM_TARGET_SINGLETON | DM_TARGET_ALWAYS_WRITEABLE,
+ .version = {1, 0, 0},
+ .module = THIS_MODULE,
+ .ctr = pool_ctr,
+ .dtr = pool_dtr,
+ .map = pool_map,
+ .postsuspend = pool_postsuspend,
+ .preresume = pool_preresume,
+ .message = pool_message,
+ .status = pool_status,
+ .merge = pool_merge,
+ .iterate_devices = pool_iterate_devices,
+ .io_hints = pool_io_hints,
+};
+
+/*----------------------------------------------------------------*/
+
+static void thin_dtr(struct dm_target *ti)
+{
+ struct thin_c *tc = ti->private;
+
+ pool_dec(tc->pool);
+ dm_pool_close_thin_device(tc->td);
+ dm_put_device(ti, tc->pool_dev);
+ kfree(tc);
+}
+
+/*
+ * Thin target parameters:
+ *
+ * <pool_dev> <dev_id>
+ *
+ * pool_dev: the path to the pool (eg, /dev/mapper/my_pool)
+ * dev_id: the internal device identifier
+ */
+static int thin_ctr(struct dm_target *ti, unsigned argc, char **argv)
+{
+ int r;
+ struct thin_c *tc;
+ struct dm_dev *pool_dev;
+ struct mapped_device *pool_md;
+
+ if (argc != 2) {
+ ti->error = "Invalid argument count";
+ return -EINVAL;
+ }
+
+ tc = ti->private = kzalloc(sizeof(*tc), GFP_KERNEL);
+ if (!tc) {
+ ti->error = "Out of memory";
+ return -ENOMEM;
+ }
+
+ r = dm_get_device(ti, argv[0], dm_table_get_mode(ti->table), &pool_dev);
+ if (r) {
+ ti->error = "Error opening pool device";
+ goto bad_pool_dev;
+ }
+ tc->pool_dev = pool_dev;
+
+ if (read_dev_id(argv[1], (unsigned long long *)&tc->dev_id, 0)) {
+ ti->error = "Invalid device id";
+ r = -EINVAL;
+ goto bad_common;
+ }
+
+ pool_md = dm_get_md(tc->pool_dev->bdev->bd_dev);
+ if (!pool_md) {
+ ti->error = "Couldn't get pool mapped device";
+ r = -EINVAL;
+ goto bad_common;
+ }
+
+ tc->pool = pool_table_lookup(pool_md);
+ if (!tc->pool) {
+ ti->error = "Couldn't find pool object";
+ r = -EINVAL;
+ goto bad_pool_lookup;
+ }
+ pool_inc(tc->pool);
+ dm_put(pool_md);
+
+ r = dm_pool_open_thin_device(tc->pool->pmd, tc->dev_id, &tc->td);
+ if (r) {
+ ti->error = "Couldn't open thin internal device";
+ goto bad_thin_open;
+ }
+
+ ti->split_io = tc->pool->sectors_per_block;
+ ti->num_flush_requests = 1;
+ ti->num_discard_requests = 0;
+ ti->discards_supported = 0;
+
+ return 0;
+
+bad_thin_open:
+ pool_dec(tc->pool);
+bad_pool_lookup:
+ dm_put(pool_md);
+bad_common:
+ dm_put_device(ti, tc->pool_dev);
+bad_pool_dev:
+ kfree(tc);
+
+ return r;
+}
+
+static int thin_map(struct dm_target *ti, struct bio *bio,
+ union map_info *map_context)
+{
+ bio->bi_sector -= ti->begin;
+
+ return thin_bio_map(ti, bio, map_context);
+}
+
+/*
+ * <nr mapped sectors> <highest mapped sector>
+ */
+static int thin_status(struct dm_target *ti, status_type_t type,
+ char *result, unsigned maxlen)
+{
+ int r;
+ ssize_t sz = 0;
+ dm_block_t mapped, highest;
+ char buf[BDEVNAME_SIZE];
+ struct thin_c *tc = ti->private;
+
+ if (!tc->td)
+ DMEMIT("-");
+ else {
+ switch (type) {
+ case STATUSTYPE_INFO:
+ r = dm_thin_get_mapped_count(tc->td, &mapped);
+ if (r)
+ return r;
+
+ r = dm_thin_get_highest_mapped_block(tc->td, &highest);
+ if (r < 0)
+ return r;
+
+ DMEMIT("%llu ", mapped * tc->pool->sectors_per_block);
+ if (r)
+ DMEMIT("%llu", ((highest + 1) *
+ tc->pool->sectors_per_block) - 1);
+ else
+ DMEMIT("-");
+ break;
+
+ case STATUSTYPE_TABLE:
+ DMEMIT("%s %lu",
+ format_dev_t(buf, tc->pool_dev->bdev->bd_dev),
+ (unsigned long) tc->dev_id);
+ break;
+ }
+ }
+
+ return 0;
+}
+
+static int thin_iterate_devices(struct dm_target *ti,
+ iterate_devices_callout_fn fn, void *data)
+{
+ struct thin_c *tc = ti->private;
+
+ return fn(ti, tc->pool_dev, 0, tc->pool->sectors_per_block, data);
+}
+
+static void thin_io_hints(struct dm_target *ti, struct queue_limits *limits)
+{
+ struct thin_c *tc = ti->private;
+
+ blk_limits_io_min(limits, 0);
+ blk_limits_io_opt(limits, tc->pool->sectors_per_block << SECTOR_SHIFT);
+}
+
+static struct target_type thin_target = {
+ .name = "thin",
+ .version = {1, 0, 0},
+ .module = THIS_MODULE,
+ .ctr = thin_ctr,
+ .dtr = thin_dtr,
+ .map = thin_map,
+ .status = thin_status,
+ .iterate_devices = thin_iterate_devices,
+ .io_hints = thin_io_hints,
+};
+
+/*----------------------------------------------------------------*/
+
+static int __init dm_thin_init(void)
+{
+ int r;
+
+ pool_table_init();
+
+ r = dm_register_target(&thin_target);
+ if (r)
+ return r;
+
+ r = dm_register_target(&pool_target);
+ if (r)
+ dm_unregister_target(&thin_target);
+
+ return r;
+}
+
+static void dm_thin_exit(void)
+{
+ dm_unregister_target(&thin_target);
+ dm_unregister_target(&pool_target);
+}
+
+module_init(dm_thin_init);
+module_exit(dm_thin_exit);
+
+MODULE_DESCRIPTION(DM_NAME "device-mapper thin provisioning target");
+MODULE_AUTHOR("Joe Thornber <dm-devel@redhat.com>");
+MODULE_LICENSE("GPL");
projects / karo-tx-linux.git / commitdiff