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.

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(-)

<snip>

diff --git a/fs/btrfs/zoned.h b/fs/btrfs/zoned.h
index 694ab6d1e..b94ce4d1f 100644
--- a/fs/btrfs/zoned.h
+++ b/fs/btrfs/zoned.h

@@ -9,6 +9,7 @@
 #include "disk-io.h"
 #include "block-group.h"
 #include "btrfs_inode.h"
+#include "misc.h"
 
 #define BTRFS_DEFAULT_RECLAIM_THRESH           			(75)
 

@@ -18,7 +19,6 @@ struct btrfs_zoned_device_info {
 	 * zoned block device.
 	 */
 	u64 zone_size;
-	u8  zone_size_shift;
 	u32 nr_zones;
 	unsigned int max_active_zones;
 	atomic_t active_zones_left;

@@ -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);
+
+	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;
+}
+