[PATCH v2] btrfs: log, when replace, is canceled by the user

[Anand Jain <anand.jain@oracle.com>]

For forensic investigations of issues, we would want to know
if and when the user cancels the replace.

Signed-off-by: Anand Jain <anand.jain@oracle.com>
---
v1->v2: use btrfs_dev_name() instead of rcu_str_deref()
        as btrfs_dev_name() also provides "missing" string,
        if needed.

 fs/btrfs/dev-replace.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/fs/btrfs/dev-replace.c b/fs/btrfs/dev-replace.c
index dd717e204b5e..3b0760f7ec8a 100644
--- a/fs/btrfs/dev-replace.c
+++ b/fs/btrfs/dev-replace.c
@@ -703,6 +703,7 @@ int btrfs_dev_replace_cancel(struct btrfs_fs_info *fs_info)
 {
 	struct btrfs_dev_replace *dev_replace = &fs_info->dev_replace;
 	struct btrfs_device *tgt_device = NULL;
+	struct btrfs_device *src_device = NULL;
 	struct btrfs_trans_handle *trans;
 	struct btrfs_root *root = fs_info->tree_root;
 	int result;
@@ -724,6 +725,7 @@ int btrfs_dev_replace_cancel(struct btrfs_fs_info *fs_info)
 	case BTRFS_IOCTL_DEV_REPLACE_STATE_SUSPENDED:
 		result = BTRFS_IOCTL_DEV_REPLACE_RESULT_NO_ERROR;
 		tgt_device = dev_replace->tgtdev;
+		src_device = dev_replace->srcdev;
 		dev_replace->tgtdev = NULL;
 		dev_replace->srcdev = NULL;
 		break;
@@ -741,6 +743,11 @@ int btrfs_dev_replace_cancel(struct btrfs_fs_info *fs_info)
 	}
 	ret = btrfs_commit_transaction(trans);
 	WARN_ON(ret);
+
+	btrfs_info(fs_info, "dev_replace from %s (devid %llu) to %s canceled",
+		   btrfs_dev_name(src_device), src_device->devid,
+		   btrfs_dev_name(tgt_device));
+
 	if (tgt_device)
 		btrfs_destroy_dev_replace_tgtdev(fs_info, tgt_device);
 
-- 
2.15.0