On 2022-05-17 14:30, David Sterba wrote:

On Mon, May 16, 2022 at 06:54:10PM +0200, Pankaj Raghav wrote:

quoted

Add helpers to calculate alignment, round up and round down
for zoned devices. These helpers encapsulates the necessary handling for
power_of_2 and non-power_of_2 zone sizes. Optimized calculations are
performed for zone sizes that are power_of_2 with log and shifts.

btrfs_zoned_is_aligned() is added instead of reusing bdev_zone_aligned()
helper due to some use cases in btrfs where zone alignment is checked
before having access to the underlying block device such as in this
function: btrfs_load_block_group_zone_info().

Use the generic btrfs zone helpers to calculate zone index, check zone
alignment, round up and round down operations.

The zone_size_shift field is not needed anymore as generic helpers are
used for calculation.

Overall this looks reasonable to me.

quoted

Reviewed-by: Luis Chamberlain <mcgrof@kernel.org>
Signed-off-by: Pankaj Raghav <redacted>
---
 fs/btrfs/volumes.c | 24 +++++++++-------
 fs/btrfs/zoned.c   | 72 ++++++++++++++++++++++------------------------
 fs/btrfs/zoned.h   | 43 +++++++++++++++++++++++----
 3 files changed, 85 insertions(+), 54 deletions(-)

--- a/fs/btrfs/zoned.c
+++ b/fs/btrfs/zoned.c

@@ -1108,14 +1101,14 @@ int btrfs_reset_device_zone(struct btrfs_device *device, u64 physical,
 int btrfs_ensure_empty_zones(struct btrfs_device *device, u64 start, u64 size)
 {
 	struct btrfs_zoned_device_info *zinfo = device->zone_info;
-	const u8 shift = zinfo->zone_size_shift;
-	unsigned long begin = start >> shift;
-	unsigned long end = (start + size) >> shift;
+	unsigned long begin = bdev_zone_no(device->bdev, start >> SECTOR_SHIFT);
+	unsigned long end =
+		bdev_zone_no(device->bdev, (start + size) >> SECTOR_SHIFT);

There are unsinged long types here though I'd rather see u64, better for
a separate patch. Fixed width types are cleaner here and in the zoned
code as there's always some conversion to/from sectors.

Ok. I will probably send a separate patch to convert them to fix width
types. Is it ok if I do it as a separate patch instead of including it
in this series?

quoted

 	u64 pos;
 	int ret;
 
-	ASSERT(IS_ALIGNED(start, zinfo->zone_size));
-	ASSERT(IS_ALIGNED(size, zinfo->zone_size));
+	ASSERT(btrfs_zoned_is_aligned(start, zinfo->zone_size));
+	ASSERT(btrfs_zoned_is_aligned(size, zinfo->zone_size));
 
 	if (end > zinfo->nr_zones)
 		return -ERANGE;

--- a/fs/btrfs/zoned.h
+++ b/fs/btrfs/zoned.h

@@ -30,6 +30,36 @@ struct btrfs_zoned_device_info {
 	u32 sb_zone_location[BTRFS_SUPER_MIRROR_MAX];
 };
 
+static inline bool btrfs_zoned_is_aligned(u64 pos, u64 zone_size)
+{
+	u64 remainder = 0;
+
+	if (is_power_of_two_u64(zone_size))
+		return IS_ALIGNED(pos, zone_size);
+
+	div64_u64_rem(pos, zone_size, &remainder);
+	return remainder == 0;
+}
+
+static inline u64 btrfs_zoned_roundup(u64 pos, u64 zone_size)
+{
+	if (is_power_of_two_u64(zone_size))
+		return ALIGN(pos, zone_size);

Please use round_up as the rounddown helper uses round_down

Ah, good catch. I will use it instead. Thanks.

quoted

+
+	return div64_u64(pos + zone_size - 1, zone_size) * zone_size;
+}
+
+static inline u64 btrfs_zoned_rounddown(u64 pos, u64 zone_size)
+{
+	u64 remainder = 0;
+	if (is_power_of_two_u64(zone_size))
+		return round_down(pos, zone_size);
+
+	div64_u64_rem(pos, zone_size, &remainder);
+	pos -= remainder;
+	return pos;
+}
+
 #ifdef CONFIG_BLK_DEV_ZONED
 int btrfs_get_dev_zone(struct btrfs_device *device, u64 pos,
 		       struct blk_zone *zone);