f2fs: support zone capacity less than zone size

NVMe Zoned Namespace devices can have zone-capacity less than zone-size.
Zone-capacity indicates the maximum number of sectors that are usable in
a zone beginning from the first sector of the zone. This makes the sectors
sectors after the zone-capacity till zone-size to be unusable.
This patch set tracks zone-size and zone-capacity in zoned devices and
calculate the usable blocks per segment and usable segments per section.

If zone-capacity is less than zone-size mark only those segments which
start before zone-capacity as free segments. All segments at and beyond
zone-capacity are treated as permanently used segments. In cases where
zone-capacity does not align with segment size the last segment will start
before zone-capacity and end beyond the zone-capacity of the zone. For
such spanning segments only sectors within the zone-capacity are used.

During writes and GC manage the usable segments in a section and usable
blocks per segment. Segments which are beyond zone-capacity are never
allocated, and do not need to be garbage collected, only the segments
which are before zone-capacity needs to garbage collected.
For spanning segments based on the number of usable blocks in that
segment, write to blocks only up to zone-capacity.

Zone-capacity is device specific and cannot be configured by the user.
Since NVMe ZNS device zones are sequentially write only, a block device
with conventional zones or any normal block device is needed along with
the ZNS device for the metadata operations of F2fs.

A typical nvme-cli output of a zoned device shows zone start and capacity
and write pointer as below:

SLBA: 0x0     WP: 0x0     Cap: 0x18800 State: EMPTY Type: SEQWRITE_REQ
SLBA: 0x20000 WP: 0x20000 Cap: 0x18800 State: EMPTY Type: SEQWRITE_REQ
SLBA: 0x40000 WP: 0x40000 Cap: 0x18800 State: EMPTY Type: SEQWRITE_REQ

Here zone size is 64MB, capacity is 49MB, WP is at zone start as the zones
are in EMPTY state. For each zone, only zone start + 49MB is usable area,
any lba/sector after 49MB cannot be read or written to, the drive will fail
any attempts to read/write. So, the second zone starts at 64MB and is
usable till 113MB (64 + 49) and the range between 113 and 128MB is
again unusable. The next zone starts at 128MB, and so on.

Signed-off-by: Aravind Ramesh <aravind.ramesh@wdc.com>
Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com>
Signed-off-by: Niklas Cassel <niklas.cassel@wdc.com>
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

1 files changed, 35 insertions, 6 deletions

diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
index dfa072fa8081..970257ee5d65 100644
--- a/fs/f2fs/super.c
+++ b/fs/f2fs/super.c
@@ -1184,6 +1184,7 @@ static void destroy_device_list(struct f2fs_sb_info *sbi)
 		blkdev_put(FDEV(i).bdev, FMODE_EXCL);
 #ifdef CONFIG_BLK_DEV_ZONED
 		kvfree(FDEV(i).blkz_seq);
+		kfree(FDEV(i).zone_capacity_blocks);
 #endif
 	}
 	kvfree(sbi->devs);
@@ -3088,13 +3089,26 @@ static int init_percpu_info(struct f2fs_sb_info *sbi)
 }
 
 #ifdef CONFIG_BLK_DEV_ZONED
+
+struct f2fs_report_zones_args {
+	struct f2fs_dev_info *dev;
+	bool zone_cap_mismatch;
+};
+
 static int f2fs_report_zone_cb(struct blk_zone *zone, unsigned int idx,
-			       void *data)
+			      void *data)
 {
-	struct f2fs_dev_info *dev = data;
+	struct f2fs_report_zones_args *rz_args = data;
+
+	if (zone->type == BLK_ZONE_TYPE_CONVENTIONAL)
+		return 0;
+
+	set_bit(idx, rz_args->dev->blkz_seq);
+	rz_args->dev->zone_capacity_blocks[idx] = zone->capacity >>
+						F2FS_LOG_SECTORS_PER_BLOCK;
+	if (zone->len != zone->capacity && !rz_args->zone_cap_mismatch)
+		rz_args->zone_cap_mismatch = true;
 
-	if (zone->type != BLK_ZONE_TYPE_CONVENTIONAL)
-		set_bit(idx, dev->blkz_seq);
 	return 0;
 }
 
@@ -3102,6 +3116,7 @@ static int init_blkz_info(struct f2fs_sb_info *sbi, int devi)
 {
 	struct block_device *bdev = FDEV(devi).bdev;
 	sector_t nr_sectors = bdev->bd_part->nr_sects;
+	struct f2fs_report_zones_args rep_zone_arg;
 	int ret;
 
 	if (!f2fs_sb_has_blkzoned(sbi))
@@ -3127,12 +3142,26 @@ static int init_blkz_info(struct f2fs_sb_info *sbi, int devi)
 	if (!FDEV(devi).blkz_seq)
 		return -ENOMEM;
 
-	/* Get block zones type */
+	/* Get block zones type and zone-capacity */
+	FDEV(devi).zone_capacity_blocks = f2fs_kzalloc(sbi,
+					FDEV(devi).nr_blkz * sizeof(block_t),
+					GFP_KERNEL);
+	if (!FDEV(devi).zone_capacity_blocks)
+		return -ENOMEM;
+
+	rep_zone_arg.dev = &FDEV(devi);
+	rep_zone_arg.zone_cap_mismatch = false;
+
 	ret = blkdev_report_zones(bdev, 0, BLK_ALL_ZONES, f2fs_report_zone_cb,
-				  &FDEV(devi));
+				  &rep_zone_arg);
 	if (ret < 0)
 		return ret;
 
+	if (!rep_zone_arg.zone_cap_mismatch) {
+		kfree(FDEV(devi).zone_capacity_blocks);
+		FDEV(devi).zone_capacity_blocks = NULL;
+	}
+
 	return 0;
 }
 #endif