[PATCH] btrfs: zoned: fix alloc_offset calculation for partly conventional block groups

[PATCH] btrfs: zoned: fix alloc_offset calculation for partly conventional block groups

[Johannes Thumshirn]

From: Johannes Thumshirn <johannes.thumshirn@wdc.com>

When one of two zones composing a DUP block group is a conventional zone,
we have the zone_info[i]->alloc_offset = WP_CONVENTIONAL. That will, of
course, not match the write pointer of the other zone, and fails that
block group.

This commit solves that issue by properly recovering the emulated write
pointer from the last allocated extent. The offset for the SINGLE, DUP,
and RAID1 are straight-forward: it is same as the end of last allocated
extent. The RAID0 and RAID10 are a bit tricky that we need to do the math
of striping.

This is the kernel equivalent of Naohiro's user-space commit:
1e85aa96e107 ("btrfs-progs: zoned: fix alloc_offset calculation for partly conventional block groups")

Signed-off-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
---
 fs/btrfs/zoned.c | 85 ++++++++++++++++++++++++++++++++++++++++--------
 1 file changed, 71 insertions(+), 14 deletions(-)

diff --git a/fs/btrfs/zoned.c b/fs/btrfs/zoned.c
index 4e122d6c19c0..69f1a6d36add 100644
--- a/fs/btrfs/zoned.c
+++ b/fs/btrfs/zoned.c
@@ -1404,7 +1404,8 @@ static int btrfs_load_block_group_single(struct btrfs_block_group *bg,
 static int btrfs_load_block_group_dup(struct btrfs_block_group *bg,
 				      struct btrfs_chunk_map *map,
 				      struct zone_info *zone_info,
-				      unsigned long *active)
+				      unsigned long *active,
+				      u64 last_alloc)
 {
 	struct btrfs_fs_info *fs_info = bg->fs_info;
 
@@ -1427,6 +1428,13 @@ static int btrfs_load_block_group_dup(struct btrfs_block_group *bg,
 			  zone_info[1].physical);
 		return -EIO;
 	}
+
+	if (zone_info[0].alloc_offset == WP_CONVENTIONAL)
+		zone_info[0].alloc_offset = last_alloc;
+
+	if (zone_info[1].alloc_offset == WP_CONVENTIONAL)
+		zone_info[1].alloc_offset = last_alloc;
+
 	if (zone_info[0].alloc_offset != zone_info[1].alloc_offset) {
 		btrfs_err(bg->fs_info,
 			  "zoned: write pointer offset mismatch of zones in DUP profile");
@@ -1447,7 +1455,8 @@ static int btrfs_load_block_group_dup(struct btrfs_block_group *bg,
 static int btrfs_load_block_group_raid1(struct btrfs_block_group *bg,
 					struct btrfs_chunk_map *map,
 					struct zone_info *zone_info,
-					unsigned long *active)
+					unsigned long *active,
+					u64 last_alloc)
 {
 	struct btrfs_fs_info *fs_info = bg->fs_info;
 	int i;
@@ -1462,10 +1471,12 @@ static int btrfs_load_block_group_raid1(struct btrfs_block_group *bg,
 	bg->zone_capacity = min_not_zero(zone_info[0].capacity, zone_info[1].capacity);
 
 	for (i = 0; i < map->num_stripes; i++) {
-		if (zone_info[i].alloc_offset == WP_MISSING_DEV ||
-		    zone_info[i].alloc_offset == WP_CONVENTIONAL)
+		if (zone_info[i].alloc_offset == WP_MISSING_DEV)
 			continue;
 
+		if (zone_info[i].alloc_offset == WP_CONVENTIONAL)
+			zone_info[i].alloc_offset = last_alloc;
+
 		if ((zone_info[0].alloc_offset != zone_info[i].alloc_offset) &&
 		    !btrfs_test_opt(fs_info, DEGRADED)) {
 			btrfs_err(fs_info,
@@ -1495,7 +1506,8 @@ static int btrfs_load_block_group_raid1(struct btrfs_block_group *bg,
 static int btrfs_load_block_group_raid0(struct btrfs_block_group *bg,
 					struct btrfs_chunk_map *map,
 					struct zone_info *zone_info,
-					unsigned long *active)
+					unsigned long *active,
+					u64 last_alloc)
 {
 	struct btrfs_fs_info *fs_info = bg->fs_info;
 
@@ -1506,10 +1518,29 @@ static int btrfs_load_block_group_raid0(struct btrfs_block_group *bg,
 	}
 
 	for (int i = 0; i < map->num_stripes; i++) {
-		if (zone_info[i].alloc_offset == WP_MISSING_DEV ||
-		    zone_info[i].alloc_offset == WP_CONVENTIONAL)
+		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 = last_alloc / map->stripe_size;
+			stripe_offset = stripe_nr * map->stripe_size;
+			full_stripe_nr = stripe_nr / map->num_stripes;
+			stripe_index = stripe_nr % map->num_stripes;
+
+			zone_info[i].alloc_offset =
+				full_stripe_nr * map->stripe_size;
+
+			if (stripe_index > i)
+				zone_info[i].alloc_offset += map->stripe_size;
+			else if (stripe_index == i)
+				zone_info[i].alloc_offset +=
+					(last_alloc - stripe_offset);
+		}
+
 		if (test_bit(0, active) != test_bit(i, active)) {
 			if (!btrfs_zone_activate(bg))
 				return -EIO;
@@ -1527,7 +1558,8 @@ static int btrfs_load_block_group_raid0(struct btrfs_block_group *bg,
 static int btrfs_load_block_group_raid10(struct btrfs_block_group *bg,
 					 struct btrfs_chunk_map *map,
 					 struct zone_info *zone_info,
-					 unsigned long *active)
+					 unsigned long *active,
+					 u64 last_alloc)
 {
 	struct btrfs_fs_info *fs_info = bg->fs_info;
 
@@ -1538,8 +1570,7 @@ static int btrfs_load_block_group_raid10(struct btrfs_block_group *bg,
 	}
 
 	for (int i = 0; i < map->num_stripes; i++) {
-		if (zone_info[i].alloc_offset == WP_MISSING_DEV ||
-		    zone_info[i].alloc_offset == WP_CONVENTIONAL)
+		if (zone_info[i].alloc_offset == WP_MISSING_DEV)
 			continue;
 
 		if (test_bit(0, active) != test_bit(i, active)) {
@@ -1550,6 +1581,28 @@ static int btrfs_load_block_group_raid10(struct btrfs_block_group *bg,
 				set_bit(BLOCK_GROUP_FLAG_ZONE_IS_ACTIVE, &bg->runtime_flags);
 		}
 
+		if (zone_info[i].alloc_offset == WP_CONVENTIONAL) {
+			u64 stripe_nr, full_stripe_nr;
+			u64 stripe_offset;
+			int stripe_index;
+
+			stripe_nr = last_alloc / map->stripe_size;
+			stripe_offset = stripe_nr * map->stripe_size;
+			full_stripe_nr = stripe_nr /
+				(map->num_stripes / map->sub_stripes);
+			stripe_index = stripe_nr %
+				(map->num_stripes / map->sub_stripes);
+
+			zone_info[i].alloc_offset =
+				full_stripe_nr * map->stripe_size;
+
+			if (stripe_index > (i / map->sub_stripes))
+				zone_info[i].alloc_offset += map->stripe_size;
+			else if (stripe_index == (i / map->sub_stripes))
+				zone_info[i].alloc_offset +=
+					(last_alloc - stripe_offset);
+		}
+
 		if ((i % map->sub_stripes) == 0) {
 			bg->zone_capacity += zone_info[i].capacity;
 			bg->alloc_offset += zone_info[i].alloc_offset;
@@ -1638,18 +1691,22 @@ int btrfs_load_block_group_zone_info(struct btrfs_block_group *cache, bool new)
 		ret = btrfs_load_block_group_single(cache, &zone_info[0], active);
 		break;
 	case BTRFS_BLOCK_GROUP_DUP:
-		ret = btrfs_load_block_group_dup(cache, map, zone_info, active);
+		ret = btrfs_load_block_group_dup(cache, map, zone_info, active,
+						 last_alloc);
 		break;
 	case BTRFS_BLOCK_GROUP_RAID1:
 	case BTRFS_BLOCK_GROUP_RAID1C3:
 	case BTRFS_BLOCK_GROUP_RAID1C4:
-		ret = btrfs_load_block_group_raid1(cache, map, zone_info, active);
+		ret = btrfs_load_block_group_raid1(cache, map, zone_info,
+						   active, last_alloc);
 		break;
 	case BTRFS_BLOCK_GROUP_RAID0:
-		ret = btrfs_load_block_group_raid0(cache, map, zone_info, active);
+		ret = btrfs_load_block_group_raid0(cache, map, zone_info,
+						   active, last_alloc);
 		break;
 	case BTRFS_BLOCK_GROUP_RAID10:
-		ret = btrfs_load_block_group_raid10(cache, map, zone_info, active);
+		ret = btrfs_load_block_group_raid10(cache, map, zone_info,
+						    active, last_alloc);
 		break;
 	case BTRFS_BLOCK_GROUP_RAID5:
 	case BTRFS_BLOCK_GROUP_RAID6:
-- 
2.49.0

Re: [PATCH] btrfs: zoned: fix alloc_offset calculation for partly conventional block groups

[kernel test robot]

Hi Johannes,

kernel test robot noticed the following build errors:

[auto build test ERROR on kdave/for-next]
[also build test ERROR on linus/master v6.15 next-20250604]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Johannes-Thumshirn/btrfs-zoned-fix-alloc_offset-calculation-for-partly-conventional-block-groups/20250604-183812
base:   https://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux.git for-next
patch link:    https://lore.kernel.org/r/20250604103730.358907-1-jth%40kernel.org
patch subject: [PATCH] btrfs: zoned: fix alloc_offset calculation for partly conventional block groups
config: i386-buildonly-randconfig-001-20250605 (https://download.01.org/0day-ci/archive/20250605/202506050355.YAxl8jV6-lkp@intel.com/config)
compiler: gcc-12 (Debian 12.2.0-14) 12.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20250605/202506050355.YAxl8jV6-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202506050355.YAxl8jV6-lkp@intel.com/

All errors (new ones prefixed by >>, old ones prefixed by <<):

>> ERROR: modpost: "__udivmoddi4" [fs/btrfs/btrfs.ko] undefined!

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki