[PATCH 12/13] btrfs: use blkdev_report_zones_cached()

[Damien Le Moal]

Modify btrfs_get_dev_zones() and btrfs_sb_log_location_bdev() to replace
the call to blkdev_report_zones() with blkdev_report_zones_cached() to
speed-up mount operations. btrfs_get_dev_zone_info() is also modified to
take into account the BLK_ZONE_COND_ACTIVE condition, which is
equivalent to either BLK_ZONE_COND_IMP_OPEN, BLK_ZONE_COND_EXP_OPEN or
BLK_ZONE_COND_CLOSED.

With this change, mounting a freshly formatted large capacity (30 TB)
SMR HDD completes under 100ms compared to over 1.8s before.

Signed-off-by: Damien Le Moal <dlemoal at kernel.org>
---
 fs/btrfs/zoned.c | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/fs/btrfs/zoned.c b/fs/btrfs/zoned.c
index 0ea0df18a8e4..a16b1a896c78 100644
--- a/fs/btrfs/zoned.c
+++ b/fs/btrfs/zoned.c
@@ -264,8 +264,8 @@ static int btrfs_get_dev_zones(struct btrfs_device *device, u64 pos,
 		}
 	}
 
-	ret = blkdev_report_zones(device->bdev, pos >> SECTOR_SHIFT, *nr_zones,
-				  copy_zone_info_cb, zones);
+	ret = blkdev_report_zones_cached(device->bdev, pos >> SECTOR_SHIFT,
+					 *nr_zones, copy_zone_info_cb, zones);
 	if (ret < 0) {
 		btrfs_err(device->fs_info,
 				 "zoned: failed to read zone %llu on %s (devid %llu)",
@@ -494,6 +494,7 @@ int btrfs_get_dev_zone_info(struct btrfs_device *device, bool populate_cache)
 			case BLK_ZONE_COND_IMP_OPEN:
 			case BLK_ZONE_COND_EXP_OPEN:
 			case BLK_ZONE_COND_CLOSED:
+			case BLK_ZONE_COND_ACTIVE:
 				__set_bit(nreported, zone_info->active_zones);
 				nactive++;
 				break;
@@ -896,9 +897,9 @@ int btrfs_sb_log_location_bdev(struct block_device *bdev, int mirror, int rw,
 	if (sb_zone + 1 >= nr_zones)
 		return -ENOENT;
 
-	ret = blkdev_report_zones(bdev, zone_start_sector(sb_zone, bdev),
-				  BTRFS_NR_SB_LOG_ZONES, copy_zone_info_cb,
-				  zones);
+	ret = blkdev_report_zones_cached(bdev, zone_start_sector(sb_zone, bdev),
+					 BTRFS_NR_SB_LOG_ZONES,
+					 copy_zone_info_cb, zones);
 	if (ret < 0)
 		return ret;
 	if (unlikely(ret != BTRFS_NR_SB_LOG_ZONES))
-- 
2.51.0