[PATCH 1/2] f2fs: support zone capacity less than zone size

[Aravind Ramesh <aravind.ramesh@wdc.com>]

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.

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>
---
 fs/f2fs/f2fs.h    |   5 ++
 fs/f2fs/segment.c | 136 ++++++++++++++++++++++++++++++++++++++++++++--
 fs/f2fs/segment.h |   6 +-
 fs/f2fs/super.c   |  41 ++++++++++++--
 4 files changed, 176 insertions(+), 12 deletions(-)

diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index e6e47618a357..73219e4e1ba4 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -1232,6 +1232,7 @@ struct f2fs_dev_info {
 #ifdef CONFIG_BLK_DEV_ZONED
 	unsigned int nr_blkz;		/* Total number of zones */
 	unsigned long *blkz_seq;	/* Bitmap indicating sequential zones */
+	block_t *zone_capacity_blocks;  /* Array of zone capacity in blks */
 #endif
 };
 
@@ -3395,6 +3396,10 @@ void f2fs_destroy_segment_manager_caches(void);
 int f2fs_rw_hint_to_seg_type(enum rw_hint hint);
 enum rw_hint f2fs_io_type_to_rw_hint(struct f2fs_sb_info *sbi,
 			enum page_type type, enum temp_type temp);
+unsigned int f2fs_usable_segs_in_sec(struct f2fs_sb_info *sbi,
+			unsigned int segno);
+unsigned int f2fs_usable_blks_in_seg(struct f2fs_sb_info *sbi,
+			unsigned int segno);
 
 /*
  * checkpoint.c
diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
index c35614d255e1..d2156f3f56a5 100644
--- a/fs/f2fs/segment.c
+++ b/fs/f2fs/segment.c
@@ -4294,9 +4294,12 @@ static void init_free_segmap(struct f2fs_sb_info *sbi)
 {
 	unsigned int start;
 	int type;
+	struct seg_entry *sentry;
 
 	for (start = 0; start < MAIN_SEGS(sbi); start++) {
-		struct seg_entry *sentry = get_seg_entry(sbi, start);
+		if (f2fs_usable_blks_in_seg(sbi, start) == 0)
+			continue;
+		sentry = get_seg_entry(sbi, start);
 		if (!sentry->valid_blocks)
 			__set_free(sbi, start);
 		else
@@ -4316,7 +4319,7 @@ static void init_dirty_segmap(struct f2fs_sb_info *sbi)
 	struct dirty_seglist_info *dirty_i = DIRTY_I(sbi);
 	struct free_segmap_info *free_i = FREE_I(sbi);
 	unsigned int segno = 0, offset = 0, secno;
-	unsigned short valid_blocks;
+	unsigned short valid_blocks, usable_blks_in_seg;
 	unsigned short blks_per_sec = BLKS_PER_SEC(sbi);
 
 	while (1) {
@@ -4326,9 +4329,10 @@ static void init_dirty_segmap(struct f2fs_sb_info *sbi)
 			break;
 		offset = segno + 1;
 		valid_blocks = get_valid_blocks(sbi, segno, false);
-		if (valid_blocks == sbi->blocks_per_seg || !valid_blocks)
+		usable_blks_in_seg = f2fs_usable_blks_in_seg(sbi, segno);
+		if (valid_blocks == usable_blks_in_seg || !valid_blocks)
 			continue;
-		if (valid_blocks > sbi->blocks_per_seg) {
+		if (valid_blocks > usable_blks_in_seg) {
 			f2fs_bug_on(sbi, 1);
 			continue;
 		}
@@ -4678,6 +4682,101 @@ int f2fs_check_write_pointer(struct f2fs_sb_info *sbi)
 
 	return 0;
 }
+
+static bool is_conv_zone(struct f2fs_sb_info *sbi, unsigned int zone_idx,
+						unsigned int dev_idx)
+{
+	if (!bdev_is_zoned(FDEV(dev_idx).bdev))
+		return true;
+	return !test_bit(zone_idx, FDEV(dev_idx).blkz_seq);
+}
+
+/* Return the zone index in the given device */
+static unsigned int get_zone_idx(struct f2fs_sb_info *sbi, unsigned int secno,
+					int dev_idx)
+{
+	block_t sec_start_blkaddr = START_BLOCK(sbi, GET_SEG_FROM_SEC(sbi, secno));
+
+	return (sec_start_blkaddr - FDEV(dev_idx).start_blk) >>
+						sbi->log_blocks_per_blkz;
+}
+
+/*
+ * Return the usable segments in a section based on the zone's
+ * corresponding zone capacity. Zone is equal to a section.
+ */
+static inline unsigned int f2fs_usable_zone_segs_in_sec(
+		struct f2fs_sb_info *sbi, unsigned int segno)
+{
+	unsigned int dev_idx, zone_idx, unusable_segs_in_sec;
+
+	dev_idx = f2fs_target_device_index(sbi, START_BLOCK(sbi, segno));
+	zone_idx = get_zone_idx(sbi, GET_SEC_FROM_SEG(sbi, segno), dev_idx);
+
+	/* Conventional zone's capacity is always equal to zone size */
+	if (is_conv_zone(sbi, zone_idx, dev_idx))
+		return sbi->segs_per_sec;
+
+	/*
+	 * If the zone_capacity_blocks array is NULL, then zone capacity
+	 * is equal to the zone size for all zones
+	 */
+	if (!FDEV(dev_idx).zone_capacity_blocks)
+		return sbi->segs_per_sec;
+
+	/* Get the segment count beyond zone capacity block */
+	unusable_segs_in_sec = (sbi->blocks_per_blkz -
+				FDEV(dev_idx).zone_capacity_blocks[zone_idx]) >>
+				sbi->log_blocks_per_seg;
+	return sbi->segs_per_sec - unusable_segs_in_sec;
+}
+
+/*
+ * Return the number of usable blocks in a segment. The number of blocks
+ * returned is always equal to the number of blocks in a segment for
+ * segments fully contained within a sequential zone capacity or a
+ * conventional zone. For segments partially contained in a sequential
+ * zone capacity, the number of usable blocks up to the zone capacity
+ * is returned. 0 is returned in all other cases.
+ */
+static inline unsigned int f2fs_usable_zone_blks_in_seg(
+			struct f2fs_sb_info *sbi, unsigned int segno)
+{
+	block_t seg_start, sec_start_blkaddr, sec_cap_blkaddr;
+	unsigned int zone_idx, dev_idx, secno;
+
+	secno = GET_SEC_FROM_SEG(sbi, segno);
+	seg_start = START_BLOCK(sbi, segno);
+	dev_idx = f2fs_target_device_index(sbi, seg_start);
+	zone_idx = get_zone_idx(sbi, secno, dev_idx);
+
+	/*
+	 * Conventional zone's capacity is always equal to zone size,
+	 * so, blocks per segment is unchanged.
+	 */
+	if (is_conv_zone(sbi, zone_idx, dev_idx))
+		return sbi->blocks_per_seg;
+
+	if (!FDEV(dev_idx).zone_capacity_blocks)
+		return sbi->blocks_per_seg;
+
+	sec_start_blkaddr = START_BLOCK(sbi, GET_SEG_FROM_SEC(sbi, secno));
+	sec_cap_blkaddr = sec_start_blkaddr +
+				FDEV(dev_idx).zone_capacity_blocks[zone_idx];
+
+	/*
+	 * If segment starts before zone capacity and spans beyond
+	 * zone capacity, then usable blocks are from seg start to
+	 * zone capacity. If the segment starts after the zone capacity,
+	 * then there are no usable blocks.
+	 */
+	if (seg_start >= sec_cap_blkaddr)
+		return 0;
+	if (seg_start + sbi->blocks_per_seg > sec_cap_blkaddr)
+		return sec_cap_blkaddr - seg_start;
+
+	return sbi->blocks_per_seg;
+}
 #else
 int f2fs_fix_curseg_write_pointer(struct f2fs_sb_info *sbi)
 {
@@ -4688,7 +4787,36 @@ int f2fs_check_write_pointer(struct f2fs_sb_info *sbi)
 {
 	return 0;
 }
+
+static inline unsigned int f2fs_usable_zone_blks_in_seg(struct f2fs_sb_info *sbi,
+							unsigned int segno)
+{
+	return 0;
+}
+
+static inline unsigned int f2fs_usable_zone_segs_in_sec(struct f2fs_sb_info *sbi,
+							unsigned int segno)
+{
+	return 0;
+}
 #endif
+unsigned int f2fs_usable_blks_in_seg(struct f2fs_sb_info *sbi,
+					unsigned int segno)
+{
+	if (f2fs_sb_has_blkzoned(sbi))
+		return f2fs_usable_zone_blks_in_seg(sbi, segno);
+
+	return sbi->blocks_per_seg;
+}
+
+unsigned int f2fs_usable_segs_in_sec(struct f2fs_sb_info *sbi,
+					unsigned int segno)
+{
+	if (f2fs_sb_has_blkzoned(sbi))
+		return f2fs_usable_zone_segs_in_sec(sbi, segno);
+
+	return sbi->segs_per_sec;
+}
 
 /*
  * Update min, max modified time for cost-benefit GC algorithm
diff --git a/fs/f2fs/segment.h b/fs/f2fs/segment.h
index f261e3e6a69b..79b0dc33feaf 100644
--- a/fs/f2fs/segment.h
+++ b/fs/f2fs/segment.h
@@ -411,6 +411,7 @@ static inline void __set_free(struct f2fs_sb_info *sbi, unsigned int segno)
 	unsigned int secno = GET_SEC_FROM_SEG(sbi, segno);
 	unsigned int start_segno = GET_SEG_FROM_SEC(sbi, secno);
 	unsigned int next;
+	unsigned int usable_segs = f2fs_usable_segs_in_sec(sbi, segno);
 
 	spin_lock(&free_i->segmap_lock);
 	clear_bit(segno, free_i->free_segmap);
@@ -418,7 +419,7 @@ static inline void __set_free(struct f2fs_sb_info *sbi, unsigned int segno)
 
 	next = find_next_bit(free_i->free_segmap,
 			start_segno + sbi->segs_per_sec, start_segno);
-	if (next >= start_segno + sbi->segs_per_sec) {
+	if (next >= start_segno + usable_segs) {
 		clear_bit(secno, free_i->free_secmap);
 		free_i->free_sections++;
 	}
@@ -444,6 +445,7 @@ static inline void __set_test_and_free(struct f2fs_sb_info *sbi,
 	unsigned int secno = GET_SEC_FROM_SEG(sbi, segno);
 	unsigned int start_segno = GET_SEG_FROM_SEC(sbi, secno);
 	unsigned int next;
+	unsigned int usable_segs = f2fs_usable_segs_in_sec(sbi, segno);
 
 	spin_lock(&free_i->segmap_lock);
 	if (test_and_clear_bit(segno, free_i->free_segmap)) {
@@ -453,7 +455,7 @@ static inline void __set_test_and_free(struct f2fs_sb_info *sbi,
 			goto skip_free;
 		next = find_next_bit(free_i->free_segmap,
 				start_segno + sbi->segs_per_sec, start_segno);
-		if (next >= start_segno + sbi->segs_per_sec) {
+		if (next >= start_segno + usable_segs) {
 			if (test_and_clear_bit(secno, free_i->free_secmap))
 				free_i->free_sections++;
 		}
diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
index 80cb7cd358f8..2686b07ae7eb 100644
--- a/fs/f2fs/super.c
+++ b/fs/f2fs/super.c
@@ -1164,6 +1164,7 @@ 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);
+		kvfree(FDEV(i).zone_capacity_blocks);
 #endif
 	}
 	kvfree(sbi->devs);
@@ -3039,13 +3040,26 @@ 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;
 }
 
@@ -3053,6 +3067,7 @@ 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))
@@ -3078,12 +3093,26 @@ 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) {
+		kvfree(FDEV(devi).zone_capacity_blocks);
+		FDEV(devi).zone_capacity_blocks = NULL;
+	}
+
 	return 0;
 }
 #endif
-- 
2.19.1