btrfs: convert btrfs_block_group::seq_zone to runtime flag

[ Upstream commit 961f5b8 ]

In zoned mode the sequential status of zone can be also tracked in the
runtime flags of block group.

Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Stable-dep-of: 0657b20 ("btrfs: fix use-after-free of new block group that became unused")
Signed-off-by: Sasha Levin <sashal@kernel.org>

fs/btrfs/block-group.h

@@ -57,6 +57,8 @@ enum btrfs_block_group_flags {
 	BLOCK_GROUP_FLAG_ZONED_DATA_RELOC,
 	/* Does the block group need to be added to the free space tree? */
 	BLOCK_GROUP_FLAG_NEEDS_FREE_SPACE,
+	/* Indicate that the block group is placed on a sequential zone */
+	BLOCK_GROUP_FLAG_SEQUENTIAL_ZONE,
 };
 
 enum btrfs_caching_type {
@@ -206,9 +208,6 @@ struct btrfs_block_group {
 	/* Lock for free space tree operations. */
 	struct mutex free_space_lock;
 
-	/* Flag indicating this block group is placed on a sequential zone */
-	bool seq_zone;
-
 	/*
 	 * Number of extents in this block group used for swap files.
 	 * All accesses protected by the spinlock 'lock'.

fs/btrfs/zoned.c

@@ -1436,7 +1436,7 @@ int btrfs_load_block_group_zone_info(struct btrfs_block_group *cache, bool new)
 	}
 
 	if (num_sequential > 0)
-		cache->seq_zone = true;
+		set_bit(BLOCK_GROUP_FLAG_SEQUENTIAL_ZONE, &cache->runtime_flags);
 
 	if (num_conventional > 0) {
 		/* Zone capacity is always zone size in emulation */
@@ -1658,7 +1658,7 @@ bool btrfs_use_zone_append(struct btrfs_inode *inode, u64 start)
 	if (!cache)
 		return false;
 
-	ret = cache->seq_zone;
+	ret = !!test_bit(BLOCK_GROUP_FLAG_SEQUENTIAL_ZONE, &cache->runtime_flags);
 	btrfs_put_block_group(cache);
 
 	return ret;
@@ -2177,7 +2177,8 @@ static void btrfs_zone_finish_endio_workfn(struct work_struct *work)
 void btrfs_schedule_zone_finish_bg(struct btrfs_block_group *bg,
 				   struct extent_buffer *eb)
 {
-	if (!bg->seq_zone || eb->start + eb->len * 2 <= bg->start + bg->zone_capacity)
+	if (!test_bit(BLOCK_GROUP_FLAG_SEQUENTIAL_ZONE, &bg->runtime_flags) ||
+	    eb->start + eb->len * 2 <= bg->start + bg->zone_capacity)
 		return;
 
 	if (WARN_ON(bg->zone_finish_work.func == btrfs_zone_finish_endio_workfn)) {