btrfs: do not subtract delalloc from avail bytes

The block group's avail bytes printed when dumping a space info subtract
the delalloc_bytes. However, as shown in btrfs_add_reserved_bytes() and
btrfs_free_reserved_bytes(), it is added or subtracted along with
"reserved" for the delalloc case, which means the "delalloc_bytes" is a
part of the "reserved" bytes. So, excluding it to calculate the avail space
counts delalloc_bytes twice, which can lead to an invalid result.

Fixes: e50b122 ("btrfs: print available space for a block group when dumping a space info")
CC: stable@vger.kernel.org # 6.6+
Signed-off-by: Naohiro Aota <naohiro.aota@wdc.com>
Reviewed-by: Boris Burkov <boris@bur.io>
Signed-off-by: David Sterba <dsterba@suse.com>

Author: naota

fs/btrfs/space-info.c

@@ -583,8 +583,7 @@ void btrfs_dump_space_info(struct btrfs_fs_info *fs_info,
 
 		spin_lock(&cache->lock);
 		avail = cache->length - cache->used - cache->pinned -
-			cache->reserved - cache->delalloc_bytes -
-			cache->bytes_super - cache->zone_unusable;
+			cache->reserved - cache->bytes_super - cache->zone_unusable;
 		btrfs_info(fs_info,
 "block group %llu has %llu bytes, %llu used %llu pinned %llu reserved %llu delalloc %llu super %llu zone_unusable (%llu bytes available) %s",
 			   cache->start, cache->length, cache->used, cache->pinned,