btrfs-progs: zoned: support zero out on zoned block device

If we zero out a region in a sequential write required zone, we cannot
write to the region until we reset the zone. Thus, we must prohibit zeroing
out to a sequential write required zone.

zero_dev_clamped() is modified to take the zone information and it calls
zero_zone_blocks() if the device is host managed to avoid writing to
sequential write required zones.

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

common/device-utils.c

@@ -68,7 +68,7 @@ int discard_blocks(int fd, u64 start, u64 len)
 	return 0;
 }
 
-static int zero_blocks(int fd, off_t start, size_t len)
+int zero_blocks(int fd, off_t start, size_t len)
 {
 	char *buf = malloc(len);
 	int ret = 0;
@@ -87,7 +87,8 @@ static int zero_blocks(int fd, off_t start, size_t len)
 #define ZERO_DEV_BYTES SZ_2M
 
 /* don't write outside the device by clamping the region to the device size */
-static int zero_dev_clamped(int fd, off_t start, ssize_t len, u64 dev_size)
+static int zero_dev_clamped(int fd, struct btrfs_zoned_device_info *zinfo,
+			    off_t start, ssize_t len, u64 dev_size)
 {
 	off_t end = max(start, start + len);
 
@@ -100,6 +101,9 @@ static int zero_dev_clamped(int fd, off_t start, ssize_t len, u64 dev_size)
 	start = min_t(u64, start, dev_size);
 	end = min_t(u64, end, dev_size);
 
+	if (zinfo && zinfo->model == ZONED_HOST_MANAGED)
+		return zero_zone_blocks(fd, zinfo, start, end - start);
+
 	return zero_blocks(fd, start, end - start);
 }
 
@@ -210,12 +214,12 @@ int btrfs_prepare_device(int fd, const char *file, u64 *block_count_ret,
 		}
 	}
 
-	ret = zero_dev_clamped(fd, 0, ZERO_DEV_BYTES, block_count);
+	ret = zero_dev_clamped(fd, zinfo, 0, ZERO_DEV_BYTES, block_count);
 	for (i = 0 ; !ret && i < BTRFS_SUPER_MIRROR_MAX; i++)
-		ret = zero_dev_clamped(fd, btrfs_sb_offset(i),
+		ret = zero_dev_clamped(fd, zinfo, btrfs_sb_offset(i),
 				       BTRFS_SUPER_INFO_SIZE, block_count);
 	if (!ret && (opflags & PREP_DEVICE_ZERO_END))
-		ret = zero_dev_clamped(fd, block_count - ZERO_DEV_BYTES,
+		ret = zero_dev_clamped(fd, zinfo, block_count - ZERO_DEV_BYTES,
 				       ZERO_DEV_BYTES, block_count);
 
 	if (ret < 0) {

common/device-utils.h

@@ -26,6 +26,7 @@
 #define	PREP_DEVICE_ZONED	(1U << 3)
 
 int discard_blocks(int fd, u64 start, u64 len);
+int zero_blocks(int fd, off_t start, size_t len);
 u64 get_partition_size(const char *dev);
 u64 disk_size(const char *path);
 u64 btrfs_device_size(int fd, struct stat *st);

kernel-shared/zoned.c

@@ -389,6 +389,34 @@ int btrfs_reset_all_zones(int fd, struct btrfs_zoned_device_info *zinfo)
 	return fsync(fd);
 }
 
+int zero_zone_blocks(int fd, struct btrfs_zoned_device_info *zinfo, off_t start,
+		     size_t len)
+{
+	size_t zone_len = zinfo->zone_size;
+	off_t ofst = start;
+	size_t count;
+	int ret;
+
+	/* Make sure that zero_blocks does not write sequential zones */
+	while (len > 0) {
+		/* Limit zero_blocks to a single zone */
+		count = min_t(size_t, len, zone_len);
+		if (count > zone_len - (ofst & (zone_len - 1)))
+			count = zone_len - (ofst & (zone_len - 1));
+
+		if (!zone_is_sequential(zinfo, ofst)) {
+			ret = zero_blocks(fd, ofst, count);
+			if (ret != 0)
+				return ret;
+		}
+
+		len -= count;
+		ofst += count;
+	}
+
+	return 0;
+}
+
 static int sb_log_location(int fd, struct blk_zone *zones, int rw, u64 *bytenr_ret)
 {
 	u64 wp;

kernel-shared/zoned.h

@@ -96,6 +96,9 @@ int btrfs_reset_chunk_zones(struct btrfs_fs_info *fs_info, u64 devid,
 			    u64 offset, u64 length);
 int btrfs_reset_all_zones(int fd, struct btrfs_zoned_device_info *zinfo);
 
+int zero_zone_blocks(int fd, struct btrfs_zoned_device_info *zinfo, off_t start,
+		     size_t len);
+
 #else
 
 #define sbread(fd, buf, offset) \
@@ -150,6 +153,13 @@ static inline int btrfs_reset_all_zones(int fd,
 	return -EOPNOTSUPP;
 }
 
+static inline int zero_zone_blocks(int fd,
+				   struct btrfs_zoned_device_info *zinfo,
+				   off_t start, size_t len)
+{
+	return -EOPNOTSUPP;
+}
+
 #endif /* BTRFS_ZONED */
 
 static inline bool btrfs_dev_is_sequential(struct btrfs_device *device, u64 pos)