btrfs: zoned: finish superblock zone once no space left for new SB

If there is no more space left for a new superblock in a superblock zone,
then it is better to ZONE_FINISH the zone and frees up the active zone
count.

Since btrfs_advance_sb_log() can now issue REQ_OP_ZONE_FINISH, we also need
to convert it to return int for the error case.

Signed-off-by: Naohiro Aota <naohiro.aota@wdc.com>
Signed-off-by: David Sterba <dsterba@suse.com>

1 files changed, 36 insertions, 16 deletions

diff --git a/fs/btrfs/zoned.c b/fs/btrfs/zoned.c
index 9cfb5b741718..17554caf8b86 100644
--- a/fs/btrfs/zoned.c
+++ b/fs/btrfs/zoned.c
@@ -789,36 +789,56 @@ static inline bool is_sb_log_zone(struct btrfs_zoned_device_info *zinfo,
 	return true;
 }
 
-void btrfs_advance_sb_log(struct btrfs_device *device, int mirror)
+int btrfs_advance_sb_log(struct btrfs_device *device, int mirror)
 {
 	struct btrfs_zoned_device_info *zinfo = device->zone_info;
 	struct blk_zone *zone;
+	int i;
 
 	if (!is_sb_log_zone(zinfo, mirror))
-		return;
+		return 0;
 
 	zone = &zinfo->sb_zones[BTRFS_NR_SB_LOG_ZONES * mirror];
-	if (zone->cond != BLK_ZONE_COND_FULL) {
+	for (i = 0; i < BTRFS_NR_SB_LOG_ZONES; i++) {
+		/* Advance the next zone */
+		if (zone->cond == BLK_ZONE_COND_FULL) {
+			zone++;
+			continue;
+		}
+
 		if (zone->cond == BLK_ZONE_COND_EMPTY)
 			zone->cond = BLK_ZONE_COND_IMP_OPEN;
 
-		zone->wp += (BTRFS_SUPER_INFO_SIZE >> SECTOR_SHIFT);
+		zone->wp += SUPER_INFO_SECTORS;
+
+		if (sb_zone_is_full(zone)) {
+			/*
+			 * No room left to write new superblock. Since
+			 * superblock is written with REQ_SYNC, it is safe to
+			 * finish the zone now.
+			 *
+			 * If the write pointer is exactly at the capacity,
+			 * explicit ZONE_FINISH is not necessary.
+			 */
+			if (zone->wp != zone->start + zone->capacity) {
+				int ret;
+
+				ret = blkdev_zone_mgmt(device->bdev,
+						REQ_OP_ZONE_FINISH, zone->start,
+						zone->len, GFP_NOFS);
+				if (ret)
+					return ret;
+			}
 
-		if (zone->wp == zone->start + zone->len)
+			zone->wp = zone->start + zone->len;
 			zone->cond = BLK_ZONE_COND_FULL;
-
-		return;
+		}
+		return 0;
 	}
 
-	zone++;
-	ASSERT(zone->cond != BLK_ZONE_COND_FULL);
-	if (zone->cond == BLK_ZONE_COND_EMPTY)
-		zone->cond = BLK_ZONE_COND_IMP_OPEN;
-
-	zone->wp += (BTRFS_SUPER_INFO_SIZE >> SECTOR_SHIFT);
-
-	if (zone->wp == zone->start + zone->len)
-		zone->cond = BLK_ZONE_COND_FULL;
+	/* All the zones are FULL. Should not reach here. */
+	ASSERT(0);
+	return -EIO;
 }
 
 int btrfs_reset_sb_log_zones(struct block_device *bdev, int mirror)