[PATCH v5 08/15] btrfs-progs: support zero out on zoned block device

[Naohiro Aota <naohiro.aota@wdc.com>]

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>
---
 common/device-utils.c | 14 +++++++++-----
 common/device-utils.h |  1 +
 common/hmzoned.c      | 28 ++++++++++++++++++++++++++++
 common/hmzoned.h      |  8 ++++++++
 4 files changed, 46 insertions(+), 5 deletions(-)

diff --git a/common/device-utils.c b/common/device-utils.c
index 2689f157aeea..2ac8e7d9802a 100644
--- a/common/device-utils.c
+++ b/common/device-utils.c
@@ -67,7 +67,7 @@ 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;
@@ -86,7 +86,8 @@ 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);
 
@@ -99,6 +100,9 @@ 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);
 }
 
@@ -212,12 +216,12 @@ 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) {
diff --git a/common/device-utils.h b/common/device-utils.h
index 885a46937e0d..7d5b622b8957 100644
--- a/common/device-utils.h
+++ b/common/device-utils.h
@@ -26,6 +26,7 @@
 #define	PREP_DEVICE_HMZONED	(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);
diff --git a/common/hmzoned.c b/common/hmzoned.c
index 5803b2c17a2b..484877743948 100644
--- a/common/hmzoned.c
+++ b/common/hmzoned.c
@@ -180,6 +180,34 @@ int btrfs_discard_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;
+}
+
 #endif
 
 int btrfs_get_zone_info(int fd, const char *file, bool hmzoned,
diff --git a/common/hmzoned.h b/common/hmzoned.h
index 631780537a77..a902717335b0 100644
--- a/common/hmzoned.h
+++ b/common/hmzoned.h
@@ -55,6 +55,8 @@ int btrfs_get_zone_info(int fd, const char *file, bool hmzoned,
 #ifdef BTRFS_ZONED
 bool zone_is_sequential(struct btrfs_zoned_device_info *zinfo, u64 bytenr);
 int btrfs_discard_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
 static inline bool zone_is_sequential(struct btrfs_zoned_device_info *zinfo,
 				      u64 bytenr)
@@ -66,6 +68,12 @@ static inline int btrfs_discard_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 */
 
 #endif /* __BTRFS_HMZONED_H__ */
-- 
2.24.0