--- /dev/null
+/*
+ * Copyright (C) 2018 Google Limited.
+ *
+ * This file is released under the GPL.
+ */
+
+#include "dm.h"
+#include "dm-core.h"
+
+#include <linux/crc32.h>
+#include <linux/dm-bufio.h>
+#include <linux/module.h>
+
+#define DM_MSG_PREFIX "bow"
+
+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;
+
+ /* Copy data */
+ ret = copy_data(bc, first_br, free_br, NULL);
+ if (ret)
+ return ret;
+
+ bc->log_sector->sector0 = free_br->sector;
+
+ set_type(bc, &free_br, SECTOR0_CURRENT);
+
+ /* 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;
+
+ 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));
+ }
+
+ 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);
+ }
+
+ mutex_destroy(&bc->ranges_lock);
+ kfree(bc->log_sector);
+ kfree(bc);
+}
+
+static void dm_bow_io_hints(struct dm_target *ti, struct queue_limits *limits)
+{
+ struct bow_context *bc = ti->private;
+ const unsigned int block_size = bc->block_size;
+
+ limits->logical_block_size =
+ max_t(unsigned int, limits->logical_block_size, block_size);
+ limits->physical_block_size =
+ max_t(unsigned int, limits->physical_block_size, block_size);
+ limits->io_min = max_t(unsigned int, limits->io_min, block_size);
+
+ if (limits->max_discard_sectors == 0) {
+ limits->discard_granularity = 1 << 12;
+ limits->max_hw_discard_sectors = 1 << 15;
+ limits->max_discard_sectors = 1 << 15;
+ bc->forward_trims = false;
+ } else {
+ limits->discard_granularity = 1 << 12;
+ bc->forward_trims = true;
+ }
+}
+
+static int dm_bow_ctr_optional(struct dm_target *ti, unsigned int argc, char **argv)
+{
+ struct bow_context *bc = ti->private;
+ struct dm_arg_set as;
+ static const struct dm_arg _args[] = {
+ {0, 1, "Invalid number of feature args"},
+ };
+ unsigned int opt_params;
+ const char *opt_string;
+ int err;
+ char dummy;
+
+ as.argc = argc;
+ as.argv = argv;
+
+ err = dm_read_arg_group(_args, &as, &opt_params, &ti->error);
+ if (err)
+ return err;
+
+ while (opt_params--) {
+ opt_string = dm_shift_arg(&as);
+ if (!opt_string) {
+ ti->error = "Not enough feature arguments";
+ return -EINVAL;
+ }
+
+ if (sscanf(opt_string, "block_size:%u%c",
+ &bc->block_size, &dummy) == 1) {
+ if (bc->block_size < SECTOR_SIZE ||
+ bc->block_size > 4096 ||
+ !is_power_of_2(bc->block_size)) {
+ ti->error = "Invalid block_size";
+ return -EINVAL;
+ }
+ } else {
+ ti->error = "Invalid feature arguments";
+ return -EINVAL;
+ }
+ }
+
+ return 0;
+}
+
+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;
+ }
+
+ bc->block_size =
+ bdev_get_queue(bc->dev->bdev)->limits.logical_block_size;
+ if (argc > 1) {
+ ret = dm_bow_ctr_optional(ti, argc - 1, &argv[1]);
+ if (ret)
+ goto bad;
+ }
+
+ 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;
+ bc->trims_total -= range_size(backup_br);
+ 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:
+ default:
+ 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)
+{
+ 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, 2, 0},
+ .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,
+ .io_hints = dm_bow_io_hints,
+};
+
+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);
projects / platform / kernel / linux-rpi.git / commitdiff