[Devel] [PATCH RHEL7 COMMIT] ploop: push_backup: merge pbd->cbt_map back to CBT

[Konstantin Khorenko]

The commit is pushed to "branch-rh7-3.10.0-327.18.2.vz7.14.x-ovz" and will appear at https://src.openvz.org/scm/ovz/vzkernel.git
after rh7-3.10.0-327.18.2.vz7.14.8
------>
commit 3bc16bb34d02489fd657d7be70bd77595f1015f9
Author: Maxim Patlasov <mpatlasov at virtuozzo.com>
Date:   Fri May 27 13:47:48 2016 +0400

    ploop: push_backup: merge pbd->cbt_map back to CBT
    
    The patch merges its copy of CBT mask back to CBT when
    push_backup internal state becomes invalid.
    
    The only exception is when userspace explicitly asks
    kernel to release pbd->cbt_map without merge:
    
    ioctl(PLOOP_IOC_PUSH_BACKUP_STOP) with ctl.status == 0.
    
    https://jira.sw.ru/browse/PSBM-47429
    
    Signed-off-by: Maxim Patlasov <mpatlasov at virtuozzo.com>
    
    v2 changes:
    khorenko@: ploop_pb_destroy() hunk added instead of ploop_push_backup_stop(),
    caused by f43eec3 ("ploop: push_backup: factor out destroy").
---
 drivers/block/ploop/dev.c         |  2 +-
 drivers/block/ploop/push_backup.c | 38 ++++++++++++++++++++++++++++++++------
 drivers/block/ploop/push_backup.h |  2 +-
 3 files changed, 34 insertions(+), 8 deletions(-)

diff --git a/drivers/block/ploop/dev.c b/drivers/block/ploop/dev.c
index 8e3f97f..07764f9 100644
--- a/drivers/block/ploop/dev.c
+++ b/drivers/block/ploop/dev.c
@@ -3808,7 +3808,7 @@ static int ploop_stop(struct ploop_device * plo, struct block_device *bdev)
 	}
 
 	clear_bit(PLOOP_S_PUSH_BACKUP, &plo->state);
-	ploop_pb_stop(plo->pbd);
+	ploop_pb_stop(plo->pbd, true);
 
 	for (p = plo->disk->minors - 1; p > 0; p--)
 		invalidate_partition(plo->disk, p);
diff --git a/drivers/block/ploop/push_backup.c b/drivers/block/ploop/push_backup.c
index 16b1a5d..376052d 100644
--- a/drivers/block/ploop/push_backup.c
+++ b/drivers/block/ploop/push_backup.c
@@ -88,6 +88,29 @@ static void ploop_pb_map_free(struct page **map, unsigned long block_max)
 	}
 }
 
+int ploop_pb_cbt_map_release(struct ploop_pushbackup_desc *pbd, bool do_merge)
+{
+	int ret = 0;
+
+	if (pbd->cbt_map == NULL)
+		return 0;
+
+	if (do_merge) {
+		ret = blk_cbt_map_merge(pbd->plo->queue,
+					pbd->cbt_uuid,
+					pbd->cbt_map,
+					pbd->cbt_block_max,
+					pbd->cbt_block_bits);
+		if (ret)
+			printk("ploop(%d): blk_cbt_map_merge() failed with "
+			       "%d\n", pbd->plo->index, ret);
+	}
+
+	ploop_pb_map_free(pbd->cbt_map, pbd->cbt_block_max);
+	pbd->cbt_map = NULL;
+	return ret;
+}
+
 struct ploop_pushbackup_desc *ploop_pb_alloc(struct ploop_device *plo)
 {
 	struct ploop_pushbackup_desc *pbd;
@@ -314,7 +337,7 @@ void ploop_pb_fini(struct ploop_pushbackup_desc *pbd)
 		mutex_unlock(&plo->sysfs_mutex);
 	}
 
-	ploop_pb_map_free(pbd->cbt_map, pbd->cbt_block_max);
+	ploop_pb_cbt_map_release(pbd, true);
 	ploop_pb_map_free(pbd->ppb_map, pbd->ppb_block_max);
 	ploop_pb_map_free(pbd->reported_map, pbd->ppb_block_max);
 
@@ -334,8 +357,6 @@ int ploop_pb_copy_cbt_to_user(struct ploop_pushbackup_desc *pbd, char *user_addr
 		user_addr += PAGE_SIZE;
 	}
 
-	ploop_pb_map_free(pbd->cbt_map, pbd->cbt_block_max);
-	pbd->cbt_map = NULL;
 	return 0;
 }
 
@@ -496,14 +517,17 @@ int ploop_pb_preq_add_pending(struct ploop_pushbackup_desc *pbd,
 	return 0;
 }
 
-unsigned long ploop_pb_stop(struct ploop_pushbackup_desc *pbd)
+unsigned long ploop_pb_stop(struct ploop_pushbackup_desc *pbd, bool do_merge)
 {
 	unsigned long ret = 0;
+	int merge_status = 0;
 	LIST_HEAD(drop_list);
 
 	if (pbd == NULL)
 		return 0;
 
+	merge_status = ploop_pb_cbt_map_release(pbd, do_merge);
+
 	spin_lock(&pbd->ppb_lock);
 
 	while (!RB_EMPTY_ROOT(&pbd->pending_tree)) {
@@ -535,7 +559,7 @@ unsigned long ploop_pb_stop(struct ploop_pushbackup_desc *pbd)
 		spin_unlock_irq(&plo->lock);
 	}
 
-	return ret;
+	return merge_status ? : ret;
 }
 
 int ploop_pb_get_pending(struct ploop_pushbackup_desc *pbd,
@@ -682,12 +706,14 @@ int ploop_pb_destroy(struct ploop_device *plo, __u32 *status)
 {
 	struct ploop_pushbackup_desc *pbd = plo->pbd;
 	unsigned long ret;
+	bool do_merge;
 
 	if (!test_and_clear_bit(PLOOP_S_PUSH_BACKUP, &plo->state))
 		return -EINVAL;
 
 	BUG_ON (!pbd);
-	ret = ploop_pb_stop(pbd);
+	do_merge = status ? *status : true;
+	ret = ploop_pb_stop(pbd, do_merge);
 
 	if (status)
 		*status = ret;
diff --git a/drivers/block/ploop/push_backup.h b/drivers/block/ploop/push_backup.h
index 1a8636a..1644785 100644
--- a/drivers/block/ploop/push_backup.h
+++ b/drivers/block/ploop/push_backup.h
@@ -4,7 +4,7 @@ struct ploop_pushbackup_desc *ploop_pb_alloc(struct ploop_device *plo);
 int ploop_pb_init(struct ploop_pushbackup_desc *pbd, __u8 *uuid, bool full);
 void ploop_pb_fini(struct ploop_pushbackup_desc *pbd);
 int ploop_pb_copy_cbt_to_user(struct ploop_pushbackup_desc *pbd, char *user_addr);
-unsigned long ploop_pb_stop(struct ploop_pushbackup_desc *pbd);
+unsigned long ploop_pb_stop(struct ploop_pushbackup_desc *pbd, bool do_merge);
 int ploop_pb_check_uuid(struct ploop_pushbackup_desc *pbd, __u8 *uuid);
 int ploop_pb_get_uuid(struct ploop_pushbackup_desc *pbd, __u8 *uuid);