btrfs: zoned: calculate allocation offset for conventional zones

Conventional zones do not have a write pointer, so we cannot use it to
determine the allocation offset for sequential allocation if a block
group contains a conventional zone.

But instead, we can consider the end of the highest addressed extent in
the block group for the allocation offset.

For new block group, we cannot calculate the allocation offset by
consulting the extent tree, because it can cause deadlock by taking
extent buffer lock after chunk mutex, which is already taken in
btrfs_make_block_group(). Since it is a new block group anyways, we can
simply set the allocation offset to 0.

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: Naohiro Aota <naohiro.aota@wdc.com>
Signed-off-by: David Sterba <dsterba@suse.com>

1 files changed, 2 insertions, 2 deletions

diff --git a/fs/btrfs/block-group.c b/fs/btrfs/block-group.c
index e6bf728496eb..6d10874189df 100644
--- a/fs/btrfs/block-group.c
+++ b/fs/btrfs/block-group.c
@@ -1856,7 +1856,7 @@ static int read_one_block_group(struct btrfs_fs_info *info,
 			goto error;
 	}
 
-	ret = btrfs_load_block_group_zone_info(cache);
+	ret = btrfs_load_block_group_zone_info(cache, false);
 	if (ret) {
 		btrfs_err(info, "zoned: failed to load zone info of bg %llu",
 			  cache->start);
@@ -2150,7 +2150,7 @@ int btrfs_make_block_group(struct btrfs_trans_handle *trans, u64 bytes_used,
 	if (btrfs_fs_compat_ro(fs_info, FREE_SPACE_TREE))
 		cache->needs_free_space = 1;
 
-	ret = btrfs_load_block_group_zone_info(cache);
+	ret = btrfs_load_block_group_zone_info(cache, true);
 	if (ret) {
 		btrfs_put_block_group(cache);
 		return ret;