[PATCH 3/3] btrfs: add more information for balance

[Goldwyn Rodrigues <rgoldwyn@suse.de>]

From: Goldwyn Rodrigues <rgoldwyn@suse.com>

Include information about the state of the balance and expected,
considered and completed statistics.

Q: I am not sure of the cancelled state, and stopping seemed more
appropriate since it was a transient state to cancelling the operation.
Would you prefer to call it cancelled?

This information is not used by user space as of now. We could use it
for "btrfs balance status" or ignore this patch for inclusion at all.

Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
---
 fs/btrfs/sysfs.c | 29 ++++++++++++++++++++++++++++-
 1 file changed, 28 insertions(+), 1 deletion(-)

diff --git a/fs/btrfs/sysfs.c b/fs/btrfs/sysfs.c
index 71950c121588..001a7ae375d0 100644
--- a/fs/btrfs/sysfs.c
+++ b/fs/btrfs/sysfs.c
@@ -808,6 +808,33 @@ static ssize_t btrfs_checksum_show(struct kobject *kobj,
 
 BTRFS_ATTR(, checksum, btrfs_checksum_show);
 
+static ssize_t btrfs_balance_show(struct btrfs_fs_info *fs_info, char *buf)
+{
+	ssize_t ret = 0;
+	struct btrfs_balance_control *bctl;
+
+	ret += scnprintf(buf, PAGE_SIZE, "balance\n");
+	spin_lock(&fs_info->balance_lock);
+	bctl = fs_info->balance_ctl;
+	if (!bctl) {
+		ret += scnprintf(buf + ret, PAGE_SIZE - ret,
+				"State: stopping\n");
+		goto out;
+	}
+	if (test_bit(BTRFS_FS_BALANCE_RUNNING, &fs_info->flags))
+		ret += scnprintf(buf + ret, PAGE_SIZE - ret,
+				"State: running\n");
+	else
+		ret += scnprintf(buf + ret, PAGE_SIZE - ret,
+				"State: paused\n");
+	ret += scnprintf(buf + ret, PAGE_SIZE - ret, "%llu %llu %llu\n",
+			bctl->stat.expected, bctl->stat.considered,
+			bctl->stat.completed);
+out:
+	spin_unlock(&fs_info->balance_lock);
+	return ret;
+}
+
 static ssize_t btrfs_exclusive_operation_show(struct kobject *kobj,
 		struct kobj_attribute *a, char *buf)
 {
@@ -816,7 +843,7 @@ static ssize_t btrfs_exclusive_operation_show(struct kobject *kobj,
 		case  BTRFS_EXCLOP_NONE:
 			return scnprintf(buf, PAGE_SIZE, "none\n");
 		case BTRFS_EXCLOP_BALANCE:
-			return scnprintf(buf, PAGE_SIZE, "balance\n");
+			return btrfs_balance_show(fs_info, buf);
 		case BTRFS_EXCLOP_DEV_ADD:
 			return scnprintf(buf, PAGE_SIZE, "device add\n");
 		case BTRFS_EXCLOP_DEV_REPLACE:
-- 
2.26.2