FAILED: Patch "btrfs: zoned: fixup last alloc pointer after extent removal for RAID1" failed to apply to 6.12-stable tree

[Sasha Levin <sashal@kernel.org>]

The patch below does not apply to the 6.12-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

Thanks,
Sasha

------------------ original commit in Linus's tree ------------------

From dda3ec9ee6b3e120603bff1b798f25b51e54ac5d Mon Sep 17 00:00:00 2001
From: Naohiro Aota <naohiro.aota@wdc.com>
Date: Wed, 17 Dec 2025 20:14:04 +0900
Subject: [PATCH] btrfs: zoned: fixup last alloc pointer after extent removal
 for RAID1

When a block group is composed of a sequential write zone and a
conventional zone, we recover the (pseudo) write pointer of the
conventional zone using the end of the last allocated position.

However, if the last extent in a block group is removed, the last extent
position will be smaller than the other real write pointer position.
Then, that will cause an error due to mismatch of the write pointers.

We can fixup this case by moving the alloc_offset to the corresponding
write pointer position.

Fixes: 568220fa9657 ("btrfs: zoned: support RAID0/1/10 on top of raid stripe tree")
CC: stable@vger.kernel.org # 6.12+
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Naohiro Aota <naohiro.aota@wdc.com>
Signed-off-by: David Sterba <dsterba@suse.com>
---
 fs/btrfs/zoned.c | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/fs/btrfs/zoned.c b/fs/btrfs/zoned.c
index d6a2480d5dc17..714f45045c84f 100644
--- a/fs/btrfs/zoned.c
+++ b/fs/btrfs/zoned.c
@@ -1491,6 +1491,21 @@ static int btrfs_load_block_group_raid1(struct btrfs_block_group *bg,
 	/* In case a device is missing we have a cap of 0, so don't use it. */
 	bg->zone_capacity = min_not_zero(zone_info[0].capacity, zone_info[1].capacity);
 
+	/*
+	 * When the last extent is removed, last_alloc can be smaller than the other write
+	 * pointer. In that case, last_alloc should be moved to the corresponding write
+	 * pointer position.
+	 */
+	for (i = 0; i < map->num_stripes; i++) {
+		if (zone_info[i].alloc_offset == WP_MISSING_DEV ||
+		    zone_info[i].alloc_offset == WP_CONVENTIONAL)
+			continue;
+		if (last_alloc <= zone_info[i].alloc_offset) {
+			last_alloc = zone_info[i].alloc_offset;
+			break;
+		}
+	}
+
 	for (i = 0; i < map->num_stripes; i++) {
 		if (zone_info[i].alloc_offset == WP_MISSING_DEV)
 			continue;
-- 
2.51.0