diff options
Diffstat (limited to 'drivers/md/dm-bow.c')
| -rw-r--r-- | drivers/md/dm-bow.c | 1233 |
1 files changed, 1233 insertions, 0 deletions
diff --git a/drivers/md/dm-bow.c b/drivers/md/dm-bow.c new file mode 100644 index 000000000000..b92da30a3d42 --- /dev/null +++ b/drivers/md/dm-bow.c @@ -0,0 +1,1233 @@ +/* + * Copyright (C) 2018 Google Limited. + * + * This file is released under the GPL. + */ + +#include "dm.h" +#include "dm-bufio.h" +#include "dm-core.h" + +#include <linux/crc32.h> +#include <linux/module.h> + +#define DM_MSG_PREFIX "bow" +#define SECTOR_SIZE 512 + +struct log_entry { + u64 source; + u64 dest; + u32 size; + u32 checksum; +} __packed; + +struct log_sector { + u32 magic; + u16 header_version; + u16 header_size; + u32 block_size; + u32 count; + u32 sequence; + sector_t sector0; + struct log_entry entries[]; +} __packed; + +/* + * MAGIC is BOW in ascii + */ +#define MAGIC 0x00574f42 +#define HEADER_VERSION 0x0100 + +/* + * A sorted set of ranges representing the state of the data on the device. + * Use an rb_tree for fast lookup of a given sector + * Consecutive ranges are always of different type - operations on this + * set must merge matching consecutive ranges. + * + * Top range is always of type TOP + */ +struct bow_range { + struct rb_node node; + sector_t sector; + enum { + INVALID, /* Type not set */ + SECTOR0, /* First sector - holds log record */ + SECTOR0_CURRENT,/* Live contents of sector0 */ + UNCHANGED, /* Original contents */ + TRIMMED, /* Range has been trimmed */ + CHANGED, /* Range has been changed */ + BACKUP, /* Range is being used as a backup */ + TOP, /* Final range - sector is size of device */ + } type; + struct list_head trimmed_list; /* list of TRIMMED ranges */ +}; + +static const char * const readable_type[] = { + "Invalid", + "Sector0", + "Sector0_current", + "Unchanged", + "Free", + "Changed", + "Backup", + "Top", +}; + +enum state { + TRIM, + CHECKPOINT, + COMMITTED, +}; + +struct bow_context { + struct dm_dev *dev; + u32 block_size; + u32 block_shift; + struct workqueue_struct *workqueue; + struct dm_bufio_client *bufio; + struct mutex ranges_lock; /* Hold to access this struct and/or ranges */ + struct rb_root ranges; + struct dm_kobject_holder kobj_holder; /* for sysfs attributes */ + atomic_t state; /* One of the enum state values above */ + u64 trims_total; + struct log_sector *log_sector; + struct list_head trimmed_list; + bool forward_trims; +}; + +sector_t range_top(struct bow_range *br) +{ + return container_of(rb_next(&br->node), struct bow_range, node) + ->sector; +} + +u64 range_size(struct bow_range *br) +{ + return (range_top(br) - br->sector) * SECTOR_SIZE; +} + +static sector_t bvec_top(struct bvec_iter *bi_iter) +{ + return bi_iter->bi_sector + bi_iter->bi_size / SECTOR_SIZE; +} + +/* + * Find the first range that overlaps with bi_iter + * bi_iter is set to the size of the overlapping sub-range + */ +static struct bow_range *find_first_overlapping_range(struct rb_root *ranges, + struct bvec_iter *bi_iter) +{ + struct rb_node *node = ranges->rb_node; + struct bow_range *br; + + while (node) { + br = container_of(node, struct bow_range, node); + + if (br->sector <= bi_iter->bi_sector + && bi_iter->bi_sector < range_top(br)) + break; + + if (bi_iter->bi_sector < br->sector) + node = node->rb_left; + else + node = node->rb_right; + } + + WARN_ON(!node); + if (!node) + return NULL; + + if (range_top(br) - bi_iter->bi_sector + < bi_iter->bi_size >> SECTOR_SHIFT) + bi_iter->bi_size = (range_top(br) - bi_iter->bi_sector) + << SECTOR_SHIFT; + + return br; +} + +void add_before(struct rb_root *ranges, struct bow_range *new_br, + struct bow_range *existing) +{ + struct rb_node *parent = &(existing->node); + struct rb_node **link = &(parent->rb_left); + + while (*link) { + parent = *link; + link = &((*link)->rb_right); + } + + rb_link_node(&new_br->node, parent, link); + rb_insert_color(&new_br->node, ranges); +} + +/* + * Given a range br returned by find_first_overlapping_range, split br into a + * leading range, a range matching the bi_iter and a trailing range. + * Leading and trailing may end up size 0 and will then be deleted. The + * new range matching the bi_iter is then returned and should have its type + * and type specific fields populated. + * If bi_iter runs off the end of the range, bi_iter is truncated accordingly + */ +static int split_range(struct bow_context *bc, struct bow_range **br, + struct bvec_iter *bi_iter) +{ + struct bow_range *new_br; + + if (bi_iter->bi_sector < (*br)->sector) { + WARN_ON(true); + return BLK_STS_IOERR; + } + + if (bi_iter->bi_sector > (*br)->sector) { + struct bow_range *leading_br = + kzalloc(sizeof(*leading_br), GFP_KERNEL); + + if (!leading_br) + return BLK_STS_RESOURCE; + + *leading_br = **br; + if (leading_br->type == TRIMMED) + list_add(&leading_br->trimmed_list, &bc->trimmed_list); + + add_before(&bc->ranges, leading_br, *br); + (*br)->sector = bi_iter->bi_sector; + } + + if (bvec_top(bi_iter) >= range_top(*br)) { + bi_iter->bi_size = (range_top(*br) - (*br)->sector) + * SECTOR_SIZE; + return BLK_STS_OK; + } + + /* new_br will be the beginning, existing br will be the tail */ + new_br = kzalloc(sizeof(*new_br), GFP_KERNEL); + if (!new_br) + return BLK_STS_RESOURCE; + + new_br->sector = (*br)->sector; + (*br)->sector = bvec_top(bi_iter); + add_before(&bc->ranges, new_br, *br); + *br = new_br; + + return BLK_STS_OK; +} + +/* + * Sets type of a range. May merge range into surrounding ranges + * Since br may be invalidated, always sets br to NULL to prevent + * usage after this is called + */ +static void set_type(struct bow_context *bc, struct bow_range **br, int type) +{ + struct bow_range *prev = container_of(rb_prev(&(*br)->node), + struct bow_range, node); + struct bow_range *next = container_of(rb_next(&(*br)->node), + struct bow_range, node); + + if ((*br)->type == TRIMMED) { + bc->trims_total -= range_size(*br); + list_del(&(*br)->trimmed_list); + } + + if (type == TRIMMED) { + bc->trims_total += range_size(*br); + list_add(&(*br)->trimmed_list, &bc->trimmed_list); + } + + (*br)->type = type; + + if (next->type == type) { + if (type == TRIMMED) + list_del(&next->trimmed_list); + rb_erase(&next->node, &bc->ranges); + kfree(next); + } + + if (prev->type == type) { + if (type == TRIMMED) + list_del(&(*br)->trimmed_list); + rb_erase(&(*br)->node, &bc->ranges); + kfree(*br); + } + + *br = NULL; +} + +static struct bow_range *find_free_range(struct bow_context *bc) +{ + if (list_empty(&bc->trimmed_list)) { + DMERR("Unable to find free space to back up to"); + return NULL; + } + + return list_first_entry(&bc->trimmed_list, struct bow_range, + trimmed_list); +} + +static sector_t sector_to_page(struct bow_context const *bc, sector_t sector) +{ + WARN_ON((sector & (((sector_t)1 << (bc->block_shift - SECTOR_SHIFT)) - 1)) + != 0); + return sector >> (bc->block_shift - SECTOR_SHIFT); +} + +static int copy_data(struct bow_context const *bc, + struct bow_range *source, struct bow_range *dest, + u32 *checksum) +{ + int i; + + if (range_size(source) != range_size(dest)) { + WARN_ON(1); + return BLK_STS_IOERR; + } + + if (checksum) + *checksum = sector_to_page(bc, source->sector); + + for (i = 0; i < range_size(source) >> bc->block_shift; ++i) { + struct dm_buffer *read_buffer, *write_buffer; + u8 *read, *write; + sector_t page = sector_to_page(bc, source->sector) + i; + + read = dm_bufio_read(bc->bufio, page, &read_buffer); + if (IS_ERR(read)) { + DMERR("Cannot read page %llu", + (unsigned long long)page); + return PTR_ERR(read); + } + + if (checksum) + *checksum = crc32(*checksum, read, bc->block_size); + + write = dm_bufio_new(bc->bufio, + sector_to_page(bc, dest->sector) + i, + &write_buffer); + if (IS_ERR(write)) { + DMERR("Cannot write sector"); + dm_bufio_release(read_buffer); + return PTR_ERR(write); + } + + memcpy(write, read, bc->block_size); + + dm_bufio_mark_buffer_dirty(write_buffer); + dm_bufio_release(write_buffer); + dm_bufio_release(read_buffer); + } + + dm_bufio_write_dirty_buffers(bc->bufio); + return BLK_STS_OK; +} + +/****** logging functions ******/ + +static int add_log_entry(struct bow_context *bc, sector_t source, sector_t dest, + unsigned int size, u32 checksum); + +static int backup_log_sector(struct bow_context *bc) +{ + struct bow_range *first_br, *free_br; + struct bvec_iter bi_iter; + u32 checksum = 0; + int ret; + + first_br = container_of(rb_first(&bc->ranges), struct bow_range, node); + + if (first_br->type != SECTOR0) { + WARN_ON(1); + return BLK_STS_IOERR; + } + + if (range_size(first_br) != bc->block_size) { + WARN_ON(1); + return BLK_STS_IOERR; + } + + free_br = find_free_range(bc); + /* No space left - return this error to userspace */ + if (!free_br) + return BLK_STS_NOSPC; + bi_iter.bi_sector = free_br->sector; + bi_iter.bi_size = bc->block_size; + ret = split_range(bc, &free_br, &bi_iter); + if (ret) + return ret; + if (bi_iter.bi_size != bc->block_size) { + WARN_ON(1); + return BLK_STS_IOERR; + } + + ret = copy_data(bc, first_br, free_br, &checksum); + if (ret) + return ret; + + bc->log_sector->count = 0; + bc->log_sector->sequence++; + ret = add_log_entry(bc, first_br->sector, free_br->sector, + range_size(first_br), checksum); + if (ret) + return ret; + + set_type(bc, &free_br, BACKUP); + return BLK_STS_OK; +} + +static int add_log_entry(struct bow_context *bc, sector_t source, sector_t dest, + unsigned int size, u32 checksum) +{ + struct dm_buffer *sector_buffer; + u8 *sector; + + if (sizeof(struct log_sector) + + sizeof(struct log_entry) * (bc->log_sector->count + 1) + > bc->block_size) { + int ret = backup_log_sector(bc); + + if (ret) + return ret; + } + + sector = dm_bufio_new(bc->bufio, 0, §or_buffer); + if (IS_ERR(sector)) { + DMERR("Cannot write boot sector"); + dm_bufio_release(sector_buffer); + return BLK_STS_NOSPC; + } + + bc->log_sector->entries[bc->log_sector->count].source = source; + bc->log_sector->entries[bc->log_sector->count].dest = dest; + bc->log_sector->entries[bc->log_sector->count].size = size; + bc->log_sector->entries[bc->log_sector->count].checksum = checksum; + bc->log_sector->count++; + + memcpy(sector, bc->log_sector, bc->block_size); + dm_bufio_mark_buffer_dirty(sector_buffer); + dm_bufio_release(sector_buffer); + dm_bufio_write_dirty_buffers(bc->bufio); + return BLK_STS_OK; +} + +static int prepare_log(struct bow_context *bc) +{ + struct bow_range *free_br, *first_br; + struct bvec_iter bi_iter; + u32 checksum = 0; + int ret; + + /* Carve out first sector as log sector */ + first_br = container_of(rb_first(&bc->ranges), struct bow_range, node); + if (first_br->type != UNCHANGED) { + WARN_ON(1); + return BLK_STS_IOERR; + } + + if (range_size(first_br) < bc->block_size) { + WARN_ON(1); + return BLK_STS_IOERR; + } + bi_iter.bi_sector = 0; + bi_iter.bi_size = bc->block_size; + ret = split_range(bc, &first_br, &bi_iter); + if (ret) + return ret; + first_br->type = SECTOR0; + if (range_size(first_br) != bc->block_size) { + WARN_ON(1); + return BLK_STS_IOERR; + } + + /* Find free sector for active sector0 reads/writes */ + free_br = find_free_range(bc); + if (!free_br) + return BLK_STS_NOSPC; + bi_iter.bi_sector = free_br->sector; + bi_iter.bi_size = bc->block_size; + ret = split_range(bc, &free_br, &bi_iter); + if (ret) + return ret; + free_br->type = SECTOR0_CURRENT; + + /* Copy data */ + ret = copy_data(bc, first_br, free_br, NULL); + if (ret) + return ret; + + bc->log_sector->sector0 = free_br->sector; + + /* Find free sector to back up original sector zero */ + free_br = find_free_range(bc); + if (!free_br) + return BLK_STS_NOSPC; + bi_iter.bi_sector = free_br->sector; + bi_iter.bi_size = bc->block_size; + ret = split_range(bc, &free_br, &bi_iter); + if (ret) + return ret; + + /* Back up */ + ret = copy_data(bc, first_br, free_br, &checksum); + if (ret) + return ret; + + /* + * Set up our replacement boot sector - it will get written when we + * add the first log entry, which we do immediately + */ + bc->log_sector->magic = MAGIC; + bc->log_sector->header_version = HEADER_VERSION; + bc->log_sector->header_size = sizeof(*bc->log_sector); + bc->log_sector->block_size = bc->block_size; + bc->log_sector->count = 0; + bc->log_sector->sequence = 0; + + /* Add log entry */ + ret = add_log_entry(bc, first_br->sector, free_br->sector, + range_size(first_br), checksum); + if (ret) + return ret; + + set_type(bc, &free_br, BACKUP); + return BLK_STS_OK; +} + +static struct bow_range *find_sector0_current(struct bow_context *bc) +{ + struct bvec_iter bi_iter; + + bi_iter.bi_sector = bc->log_sector->sector0; + bi_iter.bi_size = bc->block_size; + return find_first_overlapping_range(&bc->ranges, &bi_iter); +} + +/****** sysfs interface functions ******/ + +static ssize_t state_show(struct kobject *kobj, struct kobj_attribute *attr, + char *buf) +{ + struct bow_context *bc = container_of(kobj, struct bow_context, + kobj_holder.kobj); + + return scnprintf(buf, PAGE_SIZE, "%d\n", atomic_read(&bc->state)); +} + +static ssize_t state_store(struct kobject *kobj, struct kobj_attribute *attr, + const char *buf, size_t count) +{ + struct bow_context *bc = container_of(kobj, struct bow_context, + kobj_holder.kobj); + enum state state, original_state; + int ret; + + state = buf[0] - '0'; + if (state < TRIM || state > COMMITTED) { + DMERR("State value %d out of range", state); + return -EINVAL; + } + + mutex_lock(&bc->ranges_lock); + original_state = atomic_read(&bc->state); + if (state != original_state + 1) { + DMERR("Invalid state change from %d to %d", + original_state, state); + ret = -EINVAL; + goto bad; + } + + DMINFO("Switching to state %s", state == CHECKPOINT ? "Checkpoint" + : state == COMMITTED ? "Committed" : "Unknown"); + + if (state == CHECKPOINT) { + ret = prepare_log(bc); + if (ret) { + DMERR("Failed to switch to checkpoint state"); + goto bad; + } + } else if (state == COMMITTED) { + struct bow_range *br = find_sector0_current(bc); + struct bow_range *sector0_br = + container_of(rb_first(&bc->ranges), struct bow_range, + node); + + ret = copy_data(bc, br, sector0_br, 0); + if (ret) { + DMERR("Failed to switch to committed state"); + goto bad; + } + } + atomic_inc(&bc->state); + ret = count; + +bad: + mutex_unlock(&bc->ranges_lock); + return ret; +} + +static ssize_t free_show(struct kobject *kobj, struct kobj_attribute *attr, + char *buf) +{ + struct bow_context *bc = container_of(kobj, struct bow_context, + kobj_holder.kobj); + u64 trims_total; + + mutex_lock(&bc->ranges_lock); + trims_total = bc->trims_total; + mutex_unlock(&bc->ranges_lock); + + return scnprintf(buf, PAGE_SIZE, "%llu\n", trims_total); +} + +static struct kobj_attribute attr_state = __ATTR_RW(state); +static struct kobj_attribute attr_free = __ATTR_RO(free); + +static struct attribute *bow_attrs[] = { + &attr_state.attr, + &attr_free.attr, + NULL +}; + +static struct kobj_type bow_ktype = { + .sysfs_ops = &kobj_sysfs_ops, + .default_attrs = bow_attrs, + .release = dm_kobject_release +}; + +/****** constructor/destructor ******/ + +static void dm_bow_dtr(struct dm_target *ti) +{ + struct bow_context *bc = (struct bow_context *) ti->private; + struct kobject *kobj; + + while (rb_first(&bc->ranges)) { + struct bow_range *br = container_of(rb_first(&bc->ranges), + struct bow_range, node); + + rb_erase(&br->node, &bc->ranges); + kfree(br); + } + if (bc->workqueue) + destroy_workqueue(bc->workqueue); + if (bc->bufio) + dm_bufio_client_destroy(bc->bufio); + + kobj = &bc->kobj_holder.kobj; + if (kobj->state_initialized) { + kobject_put(kobj); + wait_for_completion(dm_get_completion_from_kobject(kobj)); + } + + kfree(bc->log_sector); + kfree(bc); +} + +static int dm_bow_ctr(struct dm_target *ti, unsigned int argc, char **argv) +{ + struct bow_context *bc; + struct bow_range *br; + int ret; + struct mapped_device *md = dm_table_get_md(ti->table); + + if (argc != 1) { + ti->error = "Invalid argument count"; + return -EINVAL; + } + + bc = kzalloc(sizeof(*bc), GFP_KERNEL); + if (!bc) { + ti->error = "Cannot allocate bow context"; + return -ENOMEM; + } + + ti->num_flush_bios = 1; + ti->num_discard_bios = 1; + ti->num_write_same_bios = 1; + ti->private = bc; + + ret = dm_get_device(ti, argv[0], dm_table_get_mode(ti->table), + &bc->dev); + if (ret) { + ti->error = "Device lookup failed"; + goto bad; + } + + if (bc->dev->bdev->bd_queue->limits.max_discard_sectors == 0) { + bc->dev->bdev->bd_queue->limits.discard_granularity = 1 << 12; + bc->dev->bdev->bd_queue->limits.max_hw_discard_sectors = 1 << 15; + bc->dev->bdev->bd_queue->limits.max_discard_sectors = 1 << 15; + bc->forward_trims = false; + } else { + bc->forward_trims = true; + } + + bc->block_size = bc->dev->bdev->bd_queue->limits.logical_block_size; + bc->block_shift = ilog2(bc->block_size); + bc->log_sector = kzalloc(bc->block_size, GFP_KERNEL); + if (!bc->log_sector) { + ti->error = "Cannot allocate log sector"; + goto bad; + } + + init_completion(&bc->kobj_holder.completion); + ret = kobject_init_and_add(&bc->kobj_holder.kobj, &bow_ktype, + &disk_to_dev(dm_disk(md))->kobj, "%s", + "bow"); + if (ret) { + ti->error = "Cannot create sysfs node"; + goto bad; + } + + mutex_init(&bc->ranges_lock); + bc->ranges = RB_ROOT; + bc->bufio = dm_bufio_client_create(bc->dev->bdev, bc->block_size, 1, 0, + NULL, NULL); + if (IS_ERR(bc->bufio)) { + ti->error = "Cannot initialize dm-bufio"; + ret = PTR_ERR(bc->bufio); + bc->bufio = NULL; + goto bad; + } + + bc->workqueue = alloc_workqueue("dm-bow", + WQ_CPU_INTENSIVE | WQ_MEM_RECLAIM + | WQ_UNBOUND, num_online_cpus()); + if (!bc->workqueue) { + ti->error = "Cannot allocate workqueue"; + ret = -ENOMEM; + goto bad; + } + + INIT_LIST_HEAD(&bc->trimmed_list); + + br = kzalloc(sizeof(*br), GFP_KERNEL); + if (!br) { + ti->error = "Cannot allocate ranges"; + ret = -ENOMEM; + goto bad; + } + + br->sector = ti->len; + br->type = TOP; + rb_link_node(&br->node, NULL, &bc->ranges.rb_node); + rb_insert_color(&br->node, &bc->ranges); + + br = kzalloc(sizeof(*br), GFP_KERNEL); + if (!br) { + ti->error = "Cannot allocate ranges"; + ret = -ENOMEM; + goto bad; + } + + br->sector = 0; + br->type = UNCHANGED; + rb_link_node(&br->node, bc->ranges.rb_node, + &bc->ranges.rb_node->rb_left); + rb_insert_color(&br->node, &bc->ranges); + + ti->discards_supported = true; + + return 0; + +bad: + dm_bow_dtr(ti); + return ret; +} + +/****** Handle writes ******/ + +static int prepare_unchanged_range(struct bow_context *bc, struct bow_range *br, + struct bvec_iter *bi_iter, + bool record_checksum) +{ + struct bow_range *backup_br; + struct bvec_iter backup_bi; + sector_t log_source, log_dest; + unsigned int log_size; + u32 checksum = 0; + int ret; + int original_type; + sector_t sector0; + + /* Find a free range */ + backup_br = find_free_range(bc); + if (!backup_br) + return BLK_STS_NOSPC; + + /* Carve out a backup range. This may be smaller than the br given */ + backup_bi.bi_sector = backup_br->sector; + backup_bi.bi_size = min(range_size(backup_br), (u64) bi_iter->bi_size); + ret = split_range(bc, &backup_br, &backup_bi); + if (ret) + return ret; + + /* + * Carve out a changed range. This will not be smaller than the backup + * br since the backup br is smaller than the source range and iterator + */ + bi_iter->bi_size = backup_bi.bi_size; + ret = split_range(bc, &br, bi_iter); + if (ret) + return ret; + if (range_size(br) != range_size(backup_br)) { + WARN_ON(1); + return BLK_STS_IOERR; + } + + + /* Copy data over */ + ret = copy_data(bc, br, backup_br, record_checksum ? &checksum : NULL); + if (ret) + return ret; + + /* Add an entry to the log */ + log_source = br->sector; + log_dest = backup_br->sector; + log_size = range_size(br); + + /* + * Set the types. Note that since set_type also amalgamates ranges + * we have to set both sectors to their final type before calling + * set_type on either + */ + original_type = br->type; + sector0 = backup_br->sector; + if (backup_br->type == TRIMMED) + list_del(&backup_br->trimmed_list); + backup_br->type = br->type == SECTOR0_CURRENT ? SECTOR0_CURRENT + : BACKUP; + br->type = CHANGED; + set_type(bc, &backup_br, backup_br->type); + + /* + * Add the log entry after marking the backup sector, since adding a log + * can cause another backup + */ + ret = add_log_entry(bc, log_source, log_dest, log_size, checksum); + if (ret) { + br->type = original_type; + return ret; + } + + /* Now it is safe to mark this backup successful */ + if (original_type == SECTOR0_CURRENT) + bc->log_sector->sector0 = sector0; + + set_type(bc, &br, br->type); + return ret; +} + +static int prepare_free_range(struct bow_context *bc, struct bow_range *br, + struct bvec_iter *bi_iter) +{ + int ret; + + ret = split_range(bc, &br, bi_iter); + if (ret) + return ret; + set_type(bc, &br, CHANGED); + return BLK_STS_OK; +} + +static int prepare_changed_range(struct bow_context *bc, struct bow_range *br, + struct bvec_iter *bi_iter) +{ + /* Nothing to do ... */ + return BLK_STS_OK; +} + +static int prepare_one_range(struct bow_context *bc, + struct bvec_iter *bi_iter) +{ + struct bow_range *br = find_first_overlapping_range(&bc->ranges, + bi_iter); + switch (br->type) { + case CHANGED: + return prepare_changed_range(bc, br, bi_iter); + + case TRIMMED: + return prepare_free_range(bc, br, bi_iter); + + case UNCHANGED: + case BACKUP: + return prepare_unchanged_range(bc, br, bi_iter, true); + + /* + * We cannot track the checksum for the active sector0, since it + * may change at any point. + */ + case SECTOR0_CURRENT: + return prepare_unchanged_range(bc, br, bi_iter, false); + + case SECTOR0: /* Handled in the dm_bow_map */ + case TOP: /* Illegal - top is off the end of the device */ + default: + WARN_ON(1); + return BLK_STS_IOERR; + } +} + +struct write_work { + struct work_struct work; + struct bow_context *bc; + struct bio *bio; +}; + +static void bow_write(struct work_struct *work) +{ + struct write_work *ww = container_of(work, struct write_work, work); + struct bow_context *bc = ww->bc; + struct bio *bio = ww->bio; + struct bvec_iter bi_iter = bio->bi_iter; + int ret = BLK_STS_OK; + + kfree(ww); + + mutex_lock(&bc->ranges_lock); + do { + ret = prepare_one_range(bc, &bi_iter); + bi_iter.bi_sector += bi_iter.bi_size / SECTOR_SIZE; + bi_iter.bi_size = bio->bi_iter.bi_size + - (bi_iter.bi_sector - bio->bi_iter.bi_sector) + * SECTOR_SIZE; + } while (!ret && bi_iter.bi_size); + + mutex_unlock(&bc->ranges_lock); + + if (!ret) { + bio_set_dev(bio, bc->dev->bdev); + submit_bio(bio); + } else { + DMERR("Write failure with error %d", -ret); + bio->bi_status = ret; + bio_endio(bio); + } +} + +static int queue_write(struct bow_context *bc, struct bio *bio) +{ + struct write_work *ww = kmalloc(sizeof(*ww), GFP_NOIO | __GFP_NORETRY + | __GFP_NOMEMALLOC | __GFP_NOWARN); + if (!ww) { + DMERR("Failed to allocate write_work"); + return -ENOMEM; + } + + INIT_WORK(&ww->work, bow_write); + ww->bc = bc; + ww->bio = bio; + queue_work(bc->workqueue, &ww->work); + return DM_MAPIO_SUBMITTED; +} + +static int handle_sector0(struct bow_context *bc, struct bio *bio) +{ + int ret = DM_MAPIO_REMAPPED; + + if (bio->bi_iter.bi_size > bc->block_size) { + struct bio * split = bio_split(bio, + bc->block_size >> SECTOR_SHIFT, + GFP_NOIO, + fs_bio_set); + if (!split) { + DMERR("Failed to split bio"); + bio->bi_status = BLK_STS_RESOURCE; + bio_endio(bio); + return DM_MAPIO_SUBMITTED; + } + + bio_chain(split, bio); + split->bi_iter.bi_sector = bc->log_sector->sector0; + bio_set_dev(split, bc->dev->bdev); + submit_bio(split); + + if (bio_data_dir(bio) == WRITE) + ret = queue_write(bc, bio); + } else { + bio->bi_iter.bi_sector = bc->log_sector->sector0; + } + + return ret; +} + +static int add_trim(struct bow_context *bc, struct bio *bio) +{ + struct bow_range *br; + struct bvec_iter bi_iter = bio->bi_iter; + + DMDEBUG("add_trim: %llu, %u", + (unsigned long long)bio->bi_iter.bi_sector, + bio->bi_iter.bi_size); + + do { + br = find_first_overlapping_range(&bc->ranges, &bi_iter); + + switch (br->type) { + case UNCHANGED: + if (!split_range(bc, &br, &bi_iter)) + set_type(bc, &br, TRIMMED); + break; + + case TRIMMED: + /* Nothing to do */ + break; + + default: + /* No other case is legal in TRIM state */ + WARN_ON(true); + break; + } + + bi_iter.bi_sector += bi_iter.bi_size / SECTOR_SIZE; + bi_iter.bi_size = bio->bi_iter.bi_size + - (bi_iter.bi_sector - bio->bi_iter.bi_sector) + * SECTOR_SIZE; + + } while (bi_iter.bi_size); + + bio_endio(bio); + return DM_MAPIO_SUBMITTED; +} + +static int remove_trim(struct bow_context *bc, struct bio *bio) +{ + struct bow_range *br; + struct bvec_iter bi_iter = bio->bi_iter; + + DMDEBUG("remove_trim: %llu, %u", + (unsigned long long)bio->bi_iter.bi_sector, + bio->bi_iter.bi_size); + + do { + br = find_first_overlapping_range(&bc->ranges, &bi_iter); + + switch (br->type) { + case UNCHANGED: + /* Nothing to do */ + break; + + case TRIMMED: + if (!split_range(bc, &br, &bi_iter)) + set_type(bc, &br, UNCHANGED); + break; + + default: + /* No other case is legal in TRIM state */ + WARN_ON(true); + break; + } + + bi_iter.bi_sector += bi_iter.bi_size / SECTOR_SIZE; + bi_iter.bi_size = bio->bi_iter.bi_size + - (bi_iter.bi_sector - bio->bi_iter.bi_sector) + * SECTOR_SIZE; + + } while (bi_iter.bi_size); + + return DM_MAPIO_REMAPPED; +} + +int remap_unless_illegal_trim(struct bow_context *bc, struct bio *bio) +{ + if (!bc->forward_trims && bio_op(bio) == REQ_OP_DISCARD) { + bio->bi_status = BLK_STS_NOTSUPP; + bio_endio(bio); + return DM_MAPIO_SUBMITTED; + } else { + bio_set_dev(bio, bc->dev->bdev); + return DM_MAPIO_REMAPPED; + } +} + +/****** dm interface ******/ + +static int dm_bow_map(struct dm_target *ti, struct bio *bio) +{ + int ret = DM_MAPIO_REMAPPED; + struct bow_context *bc = ti->private; + + if (likely(bc->state.counter == COMMITTED)) + return remap_unless_illegal_trim(bc, bio); + + if (bio_data_dir(bio) == READ && bio->bi_iter.bi_sector != 0) + return remap_unless_illegal_trim(bc, bio); + + if (atomic_read(&bc->state) != COMMITTED) { + enum state state; + + mutex_lock(&bc->ranges_lock); + state = atomic_read(&bc->state); + if (state == TRIM) { + if (bio_op(bio) == REQ_OP_DISCARD) + ret = add_trim(bc, bio); + else if (bio_data_dir(bio) == WRITE) + ret = remove_trim(bc, bio); + else + /* pass-through */; + } else if (state == CHECKPOINT) { + if (bio->bi_iter.bi_sector == 0) + ret = handle_sector0(bc, bio); + else if (bio_data_dir(bio) == WRITE) + ret = queue_write(bc, bio); + else + /* pass-through */; + } else { + /* pass-through */ + } + mutex_unlock(&bc->ranges_lock); + } + + if (ret == DM_MAPIO_REMAPPED) + return remap_unless_illegal_trim(bc, bio); + + return ret; +} + +static void dm_bow_tablestatus(struct dm_target *ti, char *result, + unsigned int maxlen) +{ + char *end = result + maxlen; + struct bow_context *bc = ti->private; + struct rb_node *i; + int trimmed_list_length = 0; + int trimmed_range_count = 0; + struct bow_range *br; + + if (maxlen == 0) + return; + result[0] = 0; + + list_for_each_entry(br, &bc->trimmed_list, trimmed_list) + if (br->type == TRIMMED) { + ++trimmed_list_length; + } else { + scnprintf(result, end - result, + "ERROR: non-trimmed entry in trimmed_list"); + return; + } + + if (!rb_first(&bc->ranges)) { + scnprintf(result, end - result, "ERROR: Empty ranges"); + return; + } + + if (container_of(rb_first(&bc->ranges), struct bow_range, node) + ->sector) { + scnprintf(result, end - result, + "ERROR: First range does not start at sector 0"); + return; + } + + for (i = rb_first(&bc->ranges); i; i = rb_next(i)) { + struct bow_range *br = container_of(i, struct bow_range, node); + + result += scnprintf(result, end - result, "%s: %llu", + readable_type[br->type], + (unsigned long long)br->sector); + if (result >= end) + return; + + result += scnprintf(result, end - result, "\n"); + if (result >= end) + return; + + if (br->type == TRIMMED) + ++trimmed_range_count; + + if (br->type == TOP) { + if (br->sector != ti->len) { + scnprintf(result, end - result, + "\nERROR: Top sector is incorrect"); + } + + if (&br->node != rb_last(&bc->ranges)) { + scnprintf(result, end - result, + "\nERROR: Top sector is not last"); + } + + break; + } + + if (!rb_next(i)) { + scnprintf(result, end - result, + "\nERROR: Last range not of type TOP"); + return; + } + + if (br->sector > range_top(br)) { + scnprintf(result, end - result, + "\nERROR: sectors out of order"); + return; + } + } + + if (trimmed_range_count != trimmed_list_length) + scnprintf(result, end - result, + "\nERROR: not all trimmed ranges in trimmed list"); +} + +static void dm_bow_status(struct dm_target *ti, status_type_t type, + unsigned int status_flags, char *result, + unsigned int maxlen) +{ + switch (type) { + case STATUSTYPE_INFO: + if (maxlen) + result[0] = 0; + break; + + case STATUSTYPE_TABLE: + dm_bow_tablestatus(ti, result, maxlen); + break; + } +} + +int dm_bow_prepare_ioctl(struct dm_target *ti, struct block_device **bdev, + fmode_t *mode) +{ + struct bow_context *bc = ti->private; + struct dm_dev *dev = bc->dev; + + *bdev = dev->bdev; + /* Only pass ioctls through if the device sizes match exactly. */ + return ti->len != i_size_read(dev->bdev->bd_inode) >> SECTOR_SHIFT; +} + +static int dm_bow_iterate_devices(struct dm_target *ti, + iterate_devices_callout_fn fn, void *data) +{ + struct bow_context *bc = ti->private; + + return fn(ti, bc->dev, 0, ti->len, data); +} + +static struct target_type bow_target = { + .name = "bow", + .version = {1, 1, 1}, + .module = THIS_MODULE, + .ctr = dm_bow_ctr, + .dtr = dm_bow_dtr, + .map = dm_bow_map, + .status = dm_bow_status, + .prepare_ioctl = dm_bow_prepare_ioctl, + .iterate_devices = dm_bow_iterate_devices, +}; + +int __init dm_bow_init(void) +{ + int r = dm_register_target(&bow_target); + + if (r < 0) + DMERR("registering bow failed %d", r); + return r; +} + +void dm_bow_exit(void) +{ + dm_unregister_target(&bow_target); +} + +MODULE_LICENSE("GPL"); + +module_init(dm_bow_init); +module_exit(dm_bow_exit); |