[PATCH 6.12 107/265] btrfs: zoned: fix stripe width calculation

Greg Kroah-Hartman
2026-03-12T20:18:40Z

From: Naohiro Aota <naohiro.aota@wdc.com>

[ Upstream commit 6a1ab50135ce829b834b448ce49867b5210a1641 ]

The stripe offset calculation in the zoned code for raid0 and raid10
wrongly uses map->stripe_size to calculate it. In fact, map->stripe_size is
the size of the device extent composing the block group, which always is
the zone_size on the zoned setup.

Fix it by using BTRFS_STRIPE_LEN and BTRFS_STRIPE_LEN_SHIFT. Also, optimize
the calculation a bit by doing the common calculation only once.

Fixes: c0d90a79e8e6 ("btrfs: zoned: fix alloc_offset calculation for partly conventional block groups")
CC: stable@vger.kernel.org # 6.17+
Signed-off-by: Naohiro Aota <naohiro.aota@wdc.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Stable-dep-of: 52ee9965d09b ("btrfs: zoned: fixup last alloc pointer after extent removal for RAID0/10")
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
fs/btrfs/zoned.c | 56 ++++++++++++++++++++++--------------------------
1 file changed, 26 insertions(+), 30 deletions(-)

diff --git a/fs/btrfs/zoned.c b/fs/btrfs/zoned.c
index bf41d9b641f58..f63885c7bedfe 100644
--- a/fs/btrfs/zoned.c
+++ b/fs/btrfs/zoned.c
@@ -1521,6 +1521,8 @@ static int btrfs_load_block_group_raid0(struct btrfs_block_group *bg,
u64 last_alloc)
{
struct btrfs_fs_info *fs_info = bg->fs_info;
+ u64 stripe_nr = 0, stripe_offset = 0;
+ u32 stripe_index = 0;

if ((map->type & BTRFS_BLOCK_GROUP_DATA) && !fs_info->stripe_root) {
btrfs_err(fs_info, "zoned: data %s needs raid-stripe-tree",
@@ -1528,28 +1530,26 @@ static int btrfs_load_block_group_raid0(struct btrfs_block_group *bg,
return -EINVAL;
}

+ if (last_alloc) {
+ u32 factor = map->num_stripes;
+
+ stripe_nr = last_alloc >> BTRFS_STRIPE_LEN_SHIFT;
+ stripe_offset = last_alloc & BTRFS_STRIPE_LEN_MASK;
+ stripe_nr = div_u64_rem(stripe_nr, factor, &stripe_index);
+ }
+
for (int i = 0; i < map->num_stripes; i++) {
if (zone_info[i].alloc_offset == WP_MISSING_DEV)
continue;

if (zone_info[i].alloc_offset == WP_CONVENTIONAL) {
- u64 stripe_nr, full_stripe_nr;
- u64 stripe_offset;
- int stripe_index;

- stripe_nr = div64_u64(last_alloc, map->stripe_size);
- stripe_offset = stripe_nr * map->stripe_size;
- full_stripe_nr = div_u64(stripe_nr, map->num_stripes);
- div_u64_rem(stripe_nr, map->num_stripes, &stripe_index);
-
- zone_info[i].alloc_offset =
- full_stripe_nr * map->stripe_size;
+ zone_info[i].alloc_offset = btrfs_stripe_nr_to_offset(stripe_nr);

if (stripe_index > i)
- zone_info[i].alloc_offset += map->stripe_size;
+ zone_info[i].alloc_offset += BTRFS_STRIPE_LEN;
else if (stripe_index == i)
- zone_info[i].alloc_offset +=
- (last_alloc - stripe_offset);
+ zone_info[i].alloc_offset += stripe_offset;
}

if (test_bit(0, active) != test_bit(i, active)) {
@@ -1573,6 +1573,8 @@ static int btrfs_load_block_group_raid10(struct btrfs_block_group *bg,
u64 last_alloc)
{
struct btrfs_fs_info *fs_info = bg->fs_info;
+ u64 stripe_nr = 0, stripe_offset = 0;
+ u32 stripe_index = 0;

if ((map->type & BTRFS_BLOCK_GROUP_DATA) && !fs_info->stripe_root) {
btrfs_err(fs_info, "zoned: data %s needs raid-stripe-tree",
@@ -1580,6 +1582,14 @@ static int btrfs_load_block_group_raid10(struct btrfs_block_group *bg,
return -EINVAL;
}

+ if (last_alloc) {
+ u32 factor = map->num_stripes / map->sub_stripes;
+
+ stripe_nr = last_alloc >> BTRFS_STRIPE_LEN_SHIFT;
+ stripe_offset = last_alloc & BTRFS_STRIPE_LEN_MASK;
+ stripe_nr = div_u64_rem(stripe_nr, factor, &stripe_index);
+ }
+
for (int i = 0; i < map->num_stripes; i++) {
if (zone_info[i].alloc_offset == WP_MISSING_DEV)
continue;
@@ -1593,26 +1603,12 @@ static int btrfs_load_block_group_raid10(struct btrfs_block_group *bg,
}

if (zone_info[i].alloc_offset == WP_CONVENTIONAL) {
- u64 stripe_nr, full_stripe_nr;
- u64 stripe_offset;
- int stripe_index;
-
- stripe_nr = div64_u64(last_alloc, map->stripe_size);
- stripe_offset = stripe_nr * map->stripe_size;
- full_stripe_nr = div_u64(stripe_nr,
- map->num_stripes / map->sub_stripes);
- div_u64_rem(stripe_nr,
- (map->num_stripes / map->sub_stripes),
- &stripe_index);
-
- zone_info[i].alloc_offset =
- full_stripe_nr * map->stripe_size;
+ zone_info[i].alloc_offset = btrfs_stripe_nr_to_offset(stripe_nr);

if (stripe_index > (i / map->sub_stripes))
- zone_info[i].alloc_offset += map->stripe_size;
+ zone_info[i].alloc_offset += BTRFS_STRIPE_LEN;
else if (stripe_index == (i / map->sub_stripes))
- zone_info[i].alloc_offset +=
- (last_alloc - stripe_offset);
+ zone_info[i].alloc_offset += stripe_offset;
}

if ((i % map->sub_stripes) == 0) {
--
2.51.0