[Devel] [PATCH RHEL COMMIT] dm: Add push backup driver
Konstantin Khorenko
khorenko at virtuozzo.com
Wed Sep 22 14:39:56 MSK 2021
The commit is pushed to "branch-rh9-5.14.vz9.1.x-ovz" and will appear at https://src.openvz.org/scm/ovz/vzkernel.git
after ark-5.14
------>
commit 45c14126baf64e1a2ba700eaef4153bc799cbf59
Author: Kirill Tkhai <ktkhai at virtuozzo.com>
Date: Wed Sep 22 14:39:56 2021 +0300
dm: Add push backup driver
Signed-off-by: Kirill Tkhai <ktkhai at virtuozzo.com>
---
drivers/md/Kconfig | 6 +-
drivers/md/Makefile | 2 +
drivers/md/dm-push-backup.c | 791 ++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 798 insertions(+), 1 deletion(-)
diff --git a/drivers/md/Kconfig b/drivers/md/Kconfig
index 2995a50c3d4f..9be03662460a 100644
--- a/drivers/md/Kconfig
+++ b/drivers/md/Kconfig
@@ -646,6 +646,10 @@ config DM_PLOOP
help
This is ploop1 format interpreter on device-mapper rails.
-
+config DM_PUSH_BACKUP
+ tristate "Push backup target support"
+ depends on BLK_DEV_DM
+ help
+ Virtuozzo push backup driver.
endif # MD
diff --git a/drivers/md/Makefile b/drivers/md/Makefile
index af19cd3e8991..3e9f4170dbb2 100644
--- a/drivers/md/Makefile
+++ b/drivers/md/Makefile
@@ -35,6 +35,7 @@ faulty-y += md-faulty.o
ploop-y += dm-ploop-target.o dm-ploop-map.o dm-ploop-cmd.o \
dm-ploop-bat.o
+push-backup-y += dm-push-backup.o
# Note: link order is important. All raid personalities
# and must come before md.o, as they each initialise
@@ -108,3 +109,4 @@ dm-verity-objs += dm-verity-verify-sig.o
endif
obj-$(CONFIG_DM_PLOOP) += ploop.o
+obj-$(CONFIG_DM_PUSH_BACKUP) += push-backup.o
diff --git a/drivers/md/dm-push-backup.c b/drivers/md/dm-push-backup.c
new file mode 100644
index 000000000000..16e8cf27211f
--- /dev/null
+++ b/drivers/md/dm-push-backup.c
@@ -0,0 +1,791 @@
+// SPDX-License-Identifier: GPL-2.0-only
+
+/*
+ * drivers/md/dm-push-backup.c
+ *
+ * Copyright (c) 2020-2021 Virtuozzo International GmbH. All rights reserved.
+ *
+ */
+
+#include "dm.h"
+#include "dm-rq.h"
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/vmalloc.h>
+#include <linux/ctype.h>
+#include <linux/dm-io.h>
+#include <linux/blk-mq.h>
+
+
+#define DM_MSG_PREFIX "push-backup"
+
+#define PB_HASH_TABLE_BITS 5
+#define PB_HASH_TABLE_SIZE (1 << PB_HASH_TABLE_BITS)
+#define PUSH_BACKUP_POOL_SIZE 128
+
+static struct kmem_cache *pbio_cache;
+
+static inline struct hlist_head *pb_htable_slot(struct hlist_head head[], u32 clu)
+{
+ return &head[hash_32(clu, PB_HASH_TABLE_BITS)];
+}
+
+struct pb_bio {
+ struct request *rq;
+ struct hlist_node hlist_node;
+ u64 start_clu;
+ u64 end_clu;
+ u64 key_clu; /* Cluster, we are waiting at the moment */
+ struct list_head list;
+};
+
+struct push_backup {
+ struct dm_target *ti;
+ struct dm_dev *origin_dev;
+ mempool_t *pbio_pool;
+ u64 clu_size;
+ u64 nr_clus;
+
+ bool alive;
+ void *map;
+ u64 map_bits;
+ void *pending_map;
+ struct hlist_head *pending_htable;
+
+ struct list_head pending;
+ s32 nr_delayed;
+
+ u64 timeout_in_jiffies;
+ u64 deadline_jiffies;
+ struct timer_list deadline_timer;
+
+ spinlock_t lock;
+ struct bio_list deferred_bios;
+
+ struct wait_queue_head waitq;
+ struct workqueue_struct *wq;
+ struct work_struct worker;
+
+ struct rw_semaphore ctl_rwsem;
+};
+
+static u64 pbio_first_required_for_backup_clu(struct push_backup *pb, struct pb_bio *pbio)
+{
+ u64 clu;
+
+ for (clu = pbio->start_clu; clu <= pbio->end_clu; clu++)
+ if (test_bit(clu, pb->map))
+ return clu;
+ return U64_MAX;
+}
+static u64 last_required_for_backup_clu(struct push_backup *pb, u64 start_clu, u64 end_clu)
+{
+ u64 clu;
+
+ for (clu = end_clu; clu >= start_clu; clu--) {
+ if (test_bit(clu, pb->map))
+ return clu;
+ if (clu == 0)
+ break;
+ }
+ return U64_MAX;
+}
+static u64 pbio_last_required_for_backup_clu(struct push_backup *pb, struct pb_bio *pbio)
+{
+ return last_required_for_backup_clu(pb, pbio->start_clu, pbio->end_clu);
+}
+
+static void init_pb_bio(struct pb_bio *pbio)
+{
+ INIT_HLIST_NODE(&pbio->hlist_node);
+ INIT_LIST_HEAD(&pbio->list);
+}
+
+static void calc_bio_clusters(struct push_backup *pb, struct request *rq,
+ u64 *start_clu, u64 *end_clu)
+{
+ loff_t off = to_bytes(blk_rq_pos(rq));
+
+ *start_clu = off / pb->clu_size;
+ *end_clu = (off + blk_rq_bytes(rq) - 1) / pb->clu_size;
+}
+
+static int setup_if_required_for_backup(struct push_backup *pb,
+ struct request *rq,
+ struct pb_bio **ret_pbio)
+{
+ u64 start_clu, end_clu, key;
+ struct pb_bio *pbio;
+
+ calc_bio_clusters(pb, rq, &start_clu, &end_clu);
+
+ key = last_required_for_backup_clu(pb, start_clu, end_clu);
+ if (key != U64_MAX) {
+ pbio = mempool_alloc(pb->pbio_pool, GFP_ATOMIC);
+ if (!pbio)
+ return -ENOMEM;
+ init_pb_bio(pbio);
+ pbio->rq = rq;
+ pbio->start_clu = start_clu;
+ pbio->end_clu = end_clu;
+ pbio->key_clu = key;
+ *ret_pbio = pbio;
+ return 1;
+ }
+ return 0;
+}
+
+static void update_pending_map(struct push_backup *pb, struct pb_bio *pbio)
+{
+ u64 clu;
+
+ for (clu = pbio->start_clu; clu <= pbio->end_clu; clu++)
+ if (test_bit(clu, pb->map))
+ set_bit(clu, pb->pending_map);
+}
+
+static void link_pending_pbio(struct push_backup *pb, struct pb_bio *pbio)
+{
+ struct hlist_head *slot = pb_htable_slot(pb->pending_htable, pbio->key_clu);
+
+ hlist_add_head(&pbio->hlist_node, slot);
+ list_add_tail(&pbio->list, &pb->pending);
+}
+
+static void unlink_pending_pbio(struct push_backup *pb, struct pb_bio *pbio)
+{
+ hlist_del_init(&pbio->hlist_node);
+ list_del_init(&pbio->list);
+}
+
+static void relink_pending_pbio(struct push_backup *pb, struct pb_bio *pbio, u64 key)
+{
+ struct hlist_head *slot = pb_htable_slot(pb->pending_htable, key);
+
+ hlist_del_init(&pbio->hlist_node);
+ pbio->key_clu = key;
+ hlist_add_head(&pbio->hlist_node, slot);
+}
+
+static struct pb_bio *find_pending_pbio(struct push_backup *pb, u64 clu)
+{
+ struct hlist_head *slot = pb_htable_slot(pb->pending_htable, clu);
+ struct pb_bio *pbio;
+
+ hlist_for_each_entry(pbio, slot, hlist_node)
+ if (pbio->key_clu == clu)
+ return pbio;
+
+ return NULL;
+}
+
+static void unlink_postponed_backup_pbio(struct push_backup *pb,
+ struct list_head *pbio_list,
+ struct pb_bio *pbio)
+{
+ lockdep_assert_held(&pb->lock);
+
+ unlink_pending_pbio(pb, pbio);
+ pb->nr_delayed -= 1;
+
+ list_add_tail(&pbio->list, pbio_list);
+}
+
+static void resubmit_pbios(struct push_backup *pb, struct list_head *list)
+{
+ struct pb_bio *pbio;
+
+ while ((pbio = list_first_entry_or_null(list, struct pb_bio, list)) != NULL) {
+ list_del_init(&pbio->list);
+ dm_requeue_original_rq(pbio->rq);
+ mempool_free(pbio, pb->pbio_pool);
+ }
+}
+
+static void cleanup_backup(struct push_backup *pb)
+{
+ struct hlist_node *tmp;
+ LIST_HEAD(pbio_list);
+ struct pb_bio *pbio;
+ int i;
+
+ spin_lock_irq(&pb->lock);
+ pb->alive = false;
+
+ for (i = 0; i < PB_HASH_TABLE_SIZE && pb->nr_delayed; i++) {
+ hlist_for_each_entry_safe(pbio, tmp, &pb->pending_htable[i], hlist_node)
+ unlink_postponed_backup_pbio(pb, &pbio_list, pbio);
+ }
+
+ WARN_ON_ONCE(pb->nr_delayed);
+ spin_unlock_irq(&pb->lock);
+
+ wake_up_interruptible(&pb->waitq); /* pb->alive = false */
+
+ if (!list_empty(&pbio_list))
+ resubmit_pbios(pb, &pbio_list);
+}
+
+static void do_pb_work(struct work_struct *ws)
+{
+ struct push_backup *pb = container_of(ws, struct push_backup, worker);
+
+ cleanup_backup(pb);
+}
+
+static void pb_timer_func(struct timer_list *timer)
+{
+ struct push_backup *pb = from_timer(pb, timer, deadline_timer);
+ u64 deadline, now = get_jiffies_64();
+ unsigned long flags;
+
+ spin_lock_irqsave(&pb->lock, flags);
+ deadline = pb->deadline_jiffies;
+ spin_unlock_irqrestore(&pb->lock, flags);
+
+ if (unlikely(time_before64(now, deadline)))
+ mod_timer(timer, deadline - now + 1);
+ else
+ queue_work(pb->wq, &pb->worker);
+}
+
+static int postpone_if_required_for_backup(struct push_backup *pb,
+ struct request *rq)
+{
+ bool queue_timer = false;
+ struct pb_bio *pbio;
+ unsigned long flags;
+ int ret = 0;
+
+ rcu_read_lock(); /* See push_backup_stop() */
+ spin_lock_irqsave(&pb->lock, flags);
+ if (!pb->alive)
+ goto unlock;
+ ret = setup_if_required_for_backup(pb, rq, &pbio);
+ if (ret <= 0)
+ goto unlock;
+
+ update_pending_map(pb, pbio);
+ link_pending_pbio(pb, pbio);
+
+ ret = 1;
+ pb->nr_delayed += 1;
+ if (pb->nr_delayed == 1) {
+ pb->deadline_jiffies = get_jiffies_64() + pb->timeout_in_jiffies;
+ queue_timer = true;
+ }
+unlock:
+ spin_unlock_irqrestore(&pb->lock, flags);
+
+ if (queue_timer)
+ mod_timer(&pb->deadline_timer, pb->timeout_in_jiffies + 1);
+ rcu_read_unlock();
+
+ if (queue_timer)
+ wake_up_interruptible(&pb->waitq);
+
+ return ret;
+}
+
+static int pb_clone_and_map(struct dm_target *ti, struct request *rq,
+ union map_info *map_context,
+ struct request **__clone)
+
+{
+ struct push_backup *pb = ti->private;
+ struct block_device *bdev = pb->origin_dev->bdev;
+ struct request_queue *q;
+ struct request *clone;
+ int ret;
+
+ if (blk_rq_bytes(rq) && op_is_write(req_op(rq))) {
+ ret = postpone_if_required_for_backup(pb, rq);
+ if (ret < 0) /* ENOMEM */
+ return DM_MAPIO_REQUEUE;
+ if (ret > 0) /* Postponed */
+ return DM_MAPIO_SUBMITTED;
+ }
+
+ q = bdev_get_queue(bdev);
+ clone = blk_get_request(q, rq->cmd_flags | REQ_NOMERGE,
+ BLK_MQ_REQ_NOWAIT);
+ if (IS_ERR(clone)) {
+ /* EBUSY, ENODEV or EWOULDBLOCK: requeue */
+ if (blk_queue_dying(q))
+ return DM_MAPIO_DELAY_REQUEUE;
+ return DM_MAPIO_REQUEUE;
+ }
+
+ clone->bio = clone->biotail = NULL;
+ clone->rq_disk = bdev->bd_disk;
+ clone->cmd_flags |= REQ_FAILFAST_TRANSPORT;
+ *__clone = clone;
+ return DM_MAPIO_REMAPPED;
+}
+
+static void pb_release_clone(struct request *clone,
+ union map_info *map_context)
+{
+ blk_put_request(clone);
+}
+
+static bool msg_wants_down_read(const char *cmd)
+{
+ if (!strcmp(cmd, "push_backup_read") ||
+ !strcmp(cmd, "push_backup_write"))
+ return true;
+
+ return false;
+}
+
+static int setup_pb(struct push_backup *pb, void __user *mask, int timeout)
+{
+ u64 i, map_bits, clus = pb->nr_clus;
+ void *map, *pending_map;
+ size_t size;
+
+ pb->deadline_jiffies = S64_MAX;
+ pb->timeout_in_jiffies = timeout * HZ;
+
+ size = DIV_ROUND_UP(clus, 8);
+ size = ALIGN(size, sizeof(unsigned long));
+
+ map = kvzalloc(size, GFP_KERNEL);
+ pending_map = kvzalloc(size, GFP_KERNEL);
+ if (!map || !pending_map)
+ goto err;
+
+ if (!mask) {
+ /* Full backup */
+ memset(map, 0xff, clus / 8);
+ for (i = round_down(clus, 8); i < clus; i++)
+ set_bit(i, map);
+ } else {
+ /* Partial backup */
+ size = DIV_ROUND_UP(clus, 8);
+ if (copy_from_user(map, mask, size))
+ goto err;
+ }
+
+ map_bits = bitmap_weight(map, clus);
+
+ spin_lock_irq(&pb->lock);
+ pb->map = map;
+ pb->map_bits = map_bits;
+ pb->pending_map = pending_map;
+ pb->alive = true;
+ spin_unlock_irq(&pb->lock);
+ return 0;
+err:
+ kvfree(map);
+ kvfree(pending_map);
+ return -EFAULT;
+}
+
+static int push_backup_start(struct push_backup *pb, u64 timeout,
+ void __user *mask)
+{
+ if (pb->alive)
+ return -EEXIST;
+ if (timeout == 0 || timeout >= 60UL * 60 * 5)
+ return -EINVAL;
+ return setup_pb(pb, mask, timeout);
+}
+
+static int push_backup_stop(struct push_backup *pb,
+ char *result, unsigned int maxlen)
+{
+ void *map = NULL, *pending_map = NULL;
+
+ if (!pb->map)
+ return -EBADF;
+ cleanup_backup(pb);
+
+ /* Wait postpone_if_required_for_backup() starts timer */
+ synchronize_rcu();
+ del_timer_sync(&pb->deadline_timer);
+ flush_workqueue(pb->wq);
+
+ spin_lock_irq(&pb->lock);
+ swap(pb->map, map);
+ swap(pb->pending_map, pending_map);
+ pb->timeout_in_jiffies = 0;
+ spin_unlock_irq(&pb->lock);
+ kvfree(map);
+ kvfree(pending_map);
+ return 0;
+}
+
+static int push_backup_read(struct push_backup *pb,
+ char *result, unsigned int maxlen)
+{
+ unsigned int left, right, sz = 0;
+ struct pb_bio *pbio;
+ int ret;
+
+ if (!pb)
+ return -EBADF;
+ if (!pb->map)
+ return -ESTALE;
+again:
+ if (wait_event_interruptible(pb->waitq,
+ !list_empty_careful(&pb->pending) ||
+ !pb->alive || !pb->map_bits))
+ return -EINTR;
+
+ spin_lock_irq(&pb->lock);
+ ret = -ESTALE;
+ if (!pb->alive)
+ goto unlock;
+ ret = 0;
+ if (!pb->map_bits)
+ goto unlock;
+ pbio = list_first_entry_or_null(&pb->pending, typeof(*pbio), list);
+ if (unlikely(!pbio)) {
+ spin_unlock_irq(&pb->lock);
+ goto again;
+ }
+
+ ret = -EBADMSG;
+ left = pbio_first_required_for_backup_clu(pb, pbio);
+ if (WARN_ON_ONCE(left == U64_MAX))
+ goto unlock;
+
+ right = find_next_zero_bit(pb->pending_map, pb->nr_clus, left + 1);
+ if (right < pb->nr_clus)
+ right -= 1;
+ else
+ right = pb->nr_clus - 1;
+
+ DMEMIT("%u:%u", left, right - left + 1);
+ ret = 1;
+unlock:
+ spin_unlock_irq(&pb->lock);
+ return ret;
+}
+
+static int push_backup_write(struct push_backup *pb,
+ unsigned int clu, unsigned int nr)
+{
+ u64 i, key, nr_clus = pb->nr_clus;
+ bool finished, has_more = false;
+ LIST_HEAD(pbio_list);
+ struct pb_bio *pbio;
+
+ if (!pb)
+ return -EBADF;
+ if (clu >= nr_clus || nr > nr_clus - clu)
+ return -E2BIG;
+ if (!pb->map)
+ return -ESTALE;
+
+ spin_lock_irq(&pb->lock);
+ if (!pb->alive) {
+ spin_unlock_irq(&pb->lock);
+ return -ESTALE;
+ }
+
+ for (i = clu; i < clu + nr; i++) {
+ if (test_bit(i, pb->map)) {
+ clear_bit(i, pb->map);
+ clear_bit(i, pb->pending_map);
+ pb->map_bits--;
+ }
+ }
+
+ finished = (pb->map_bits == 0);
+
+ for (i = clu; i < clu + nr; i++) {
+ while (1) {
+ pbio = find_pending_pbio(pb, i);
+ if (!pbio)
+ break;
+ key = pbio_last_required_for_backup_clu(pb, pbio);
+ if (key != U64_MAX) {
+ /*
+ * There is one or more clusters-to-backup
+ * required for this bio. Wait for them.
+ * Userspace possible backups clusters
+ * from smallest to biggest, so we use
+ * last clu as key.
+ */
+ relink_pending_pbio(pb, pbio, key);
+ continue;
+ }
+ /*
+ * All clusters of this bios were backuped or
+ * they are not needed for backup.
+ */
+ unlink_postponed_backup_pbio(pb, &pbio_list, pbio);
+ }
+ }
+
+ has_more = (pb->nr_delayed != 0);
+ if (has_more)
+ pb->deadline_jiffies = get_jiffies_64() + pb->timeout_in_jiffies;
+ else
+ pb->deadline_jiffies = S64_MAX;
+ spin_unlock_irq(&pb->lock);
+
+ if (finished)
+ wake_up_interruptible(&pb->waitq);
+
+ if (!list_empty(&pbio_list)) {
+ resubmit_pbios(pb, &pbio_list);
+ if (has_more)
+ mod_timer(&pb->deadline_timer, pb->timeout_in_jiffies + 1);
+ }
+
+ return 0;
+}
+
+static int push_backup_statistics(struct push_backup *pb, char *result,
+ unsigned int maxlen)
+{
+ unsigned int sz = 0;
+ s64 expires;
+
+ spin_lock_irq(&pb->lock);
+ expires = pb->timeout_in_jiffies;
+ if (pb->alive) {
+ if (pb->deadline_jiffies != S64_MAX)
+ expires = pb->deadline_jiffies - jiffies_64;
+ } else if (pb->map) {
+ expires = pb->deadline_jiffies - jiffies_64;
+ }
+ DMEMIT("nr_remaining_clus=%llu\n", pb->map_bits);
+ DMEMIT("nr_delayed_bios=%d\n", pb->nr_delayed);
+ DMEMIT("expires_in=%lld\n", expires / HZ);
+ spin_unlock_irq(&pb->lock);
+ return 1;
+}
+
+static int pb_message(struct dm_target *ti, unsigned int argc, char **argv,
+ char *result, unsigned int maxlen)
+{
+ struct push_backup *pb = ti->private;
+ int ret = -EPERM;
+ u64 val, val2;
+ bool read;
+
+ if (!capable(CAP_SYS_ADMIN))
+ goto out;
+
+ ret = -EINVAL;
+ if (argc < 1)
+ goto out;
+
+ read = msg_wants_down_read(argv[0]);
+ if (read)
+ down_read(&pb->ctl_rwsem);
+ else
+ down_write(&pb->ctl_rwsem);
+
+ if (!strcmp(argv[0], "push_backup_start")) {
+ if (argc < 2 || argc > 3)
+ goto unlock;
+ if (kstrtou64(argv[1], 10, &val) < 0)
+ goto unlock;
+ val2 = 0;
+ if (argc == 3 && kstrtou64(argv[2], 10, &val2) < 0)
+ goto unlock;
+ ret = push_backup_start(pb, val, (void *)val2);
+ } else if (!strcmp(argv[0], "push_backup_stop")) {
+ if (argc != 1)
+ goto unlock;
+ ret = push_backup_stop(pb, result, maxlen);
+ } else if (!strcmp(argv[0], "push_backup_read")) {
+ if (argc != 1)
+ goto unlock;
+ ret = push_backup_read(pb, result, maxlen);
+ } else if (!strcmp(argv[0], "push_backup_write")) {
+ if (argc != 2 || sscanf(argv[1], "%llu:%llu", &val, &val2) != 2)
+ goto unlock;
+ ret = push_backup_write(pb, val, val2);
+ } else if (!strcmp(argv[0], "push_backup_statistics")) {
+ ret = push_backup_statistics(pb, result, maxlen);
+ } else {
+ ret = -ENOTSUPP;
+ }
+
+unlock:
+ if (read)
+ up_read(&pb->ctl_rwsem);
+ else
+ up_write(&pb->ctl_rwsem);
+out:
+ return ret;
+}
+static void pb_destroy(struct push_backup *pb)
+{
+ WARN_ON_ONCE(pb->nr_delayed);
+
+ del_timer_sync(&pb->deadline_timer);
+ if (pb->wq)
+ destroy_workqueue(pb->wq);
+ kvfree(pb->map); /* Is's not zero if stop was not called */
+ kvfree(pb->pending_map);
+ kvfree(pb->pending_htable);
+ mempool_destroy(pb->pbio_pool);
+ if (pb->origin_dev)
+ dm_put_device(pb->ti, pb->origin_dev);
+ kfree(pb);
+}
+
+/*
+ * <cluster size> <data dev>
+ */
+static int pb_ctr(struct dm_target *ti, unsigned int argc, char **argv)
+{
+ struct push_backup *pb;
+ u32 sectors;
+ int ret;
+
+ if (argc < 2 || ti->begin != 0)
+ return -EINVAL;
+
+ ret = -ENOMEM;
+ pb = kzalloc(sizeof(*pb), GFP_KERNEL);
+ if (!pb)
+ goto err;
+
+ pb->pbio_pool = mempool_create_slab_pool(PUSH_BACKUP_POOL_SIZE,
+ pbio_cache);
+ pb->pending_htable = kcalloc(PB_HASH_TABLE_SIZE,
+ sizeof(struct hlist_head),
+ GFP_KERNEL);
+ if (!pb->pbio_pool || !pb->pending_htable)
+ goto err;
+
+ spin_lock_init(&pb->lock);
+ init_rwsem(&pb->ctl_rwsem);
+ bio_list_init(&pb->deferred_bios);
+ INIT_LIST_HEAD(&pb->pending);
+ timer_setup(&pb->deadline_timer, pb_timer_func, 0);
+
+ init_waitqueue_head(&pb->waitq);
+ INIT_WORK(&pb->worker, do_pb_work);
+
+ ti->private = pb;
+ pb->ti = ti;
+
+ if (kstrtou32(argv[0], 10, §ors) < 0) {
+ ret = -EINVAL;
+ ti->error = "could not parse cluster size";
+ goto err;
+ }
+ pb->clu_size = to_bytes(sectors);
+ pb->nr_clus = DIV_ROUND_UP(ti->len, sectors);
+
+ /*
+ * We do not add FMODE_EXCL, because further open_table_device()
+ * unconditionally adds it. See call stack.
+ */
+ ret = dm_get_device(ti, argv[1], dm_table_get_mode(ti->table),
+ &pb->origin_dev);
+ if (ret) {
+ ti->error = "Error opening origin device";
+ goto err;
+ }
+
+ pb->wq = alloc_ordered_workqueue("dm-" DM_MSG_PREFIX, WQ_MEM_RECLAIM);
+ if (!pb->wq) {
+ ti->error = "could not create workqueue for metadata object";
+ goto err;
+ }
+
+ ti->num_flush_bios = 1;
+ ti->flush_supported = true;
+ ti->num_discard_bios = 1;
+ ti->discards_supported = true;
+ return 0;
+err:
+ if (pb)
+ pb_destroy(pb);
+ return ret;
+}
+
+static void pb_dtr(struct dm_target *ti)
+{
+ pb_destroy(ti->private);
+}
+
+static sector_t get_dev_size(struct dm_dev *dev)
+{
+ return i_size_read(dev->bdev->bd_inode) >> SECTOR_SHIFT;
+}
+
+static int pb_iterate_devices(struct dm_target *ti,
+ iterate_devices_callout_fn fn, void *data)
+{
+ struct push_backup *pb = ti->private;
+ sector_t size;
+
+ size = get_dev_size(pb->origin_dev);
+
+ return fn(ti, pb->origin_dev, 0, size, data);
+}
+
+static void pb_status(struct dm_target *ti, status_type_t type,
+ unsigned int status_flags, char *result,
+ unsigned int maxlen)
+{
+ struct push_backup *pb = ti->private;
+ const char *status = "inactive";
+ ssize_t sz = 0;
+
+ spin_lock_irq(&pb->lock);
+ if (pb->alive)
+ status = "active";
+ else if (pb->map)
+ status = "expired";
+ DMEMIT("%s %llu %llu %s", pb->origin_dev->name, to_sector(pb->clu_size),
+ pb->timeout_in_jiffies / HZ, status);
+ spin_unlock_irq(&pb->lock);
+}
+
+static struct target_type pb_target = {
+ .name = "push_backup",
+ .version = {1, 0, 0},
+ .features = DM_TARGET_SINGLETON,
+ .module = THIS_MODULE,
+ .ctr = pb_ctr,
+ .dtr = pb_dtr,
+ .clone_and_map_rq = pb_clone_and_map,
+ .release_clone_rq = pb_release_clone,
+ .message = pb_message,
+ .iterate_devices = pb_iterate_devices,
+ .status = pb_status,
+};
+
+static int __init dm_pb_init(void)
+{
+ int r;
+
+ pbio_cache = kmem_cache_create("pb_bio", sizeof(struct pb_bio), 0, 0, NULL);
+ if (!pbio_cache)
+ return -ENOMEM;
+
+ r = dm_register_target(&pb_target);
+ if (r) {
+ DMERR("pb target registration failed: %d", r);
+ goto err;
+ }
+out:
+ return r;
+err:
+ kmem_cache_destroy(pbio_cache);
+ goto out;
+}
+
+static void __exit dm_pb_exit(void)
+{
+ dm_unregister_target(&pb_target);
+ kmem_cache_destroy(pbio_cache);
+}
+
+module_init(dm_pb_init);
+module_exit(dm_pb_exit);
+
+MODULE_AUTHOR("Kirill Tkhai <ktkhai at virtuozzo.com>");
+MODULE_LICENSE("GPL v2");
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