[PATCH] btrfs-progs: fix cross stripe boundary check

[David Sterba <dsterba@suse.com>]

Commit 854437ca3c228d8ab3eb24d2efc1c21b5d56a635 ("btrfs-progs:
extent-tree: avoid allocating tree block that crosses stripe boundary")
does not work for 64k nodesize. Due to an off-by-one error, all queries
to check_crossing_stripes will return that all extents cross a stripe
and this will lead to a false ENOSPC. This crashes later

$ ./mkfs.btrfs -n 64k image

./mkfs.btrfs(btrfs_reserve_extent+0xb77)[0x417f38]
./mkfs.btrfs(btrfs_alloc_free_block+0x57)[0x417fe0]
./mkfs.btrfs(__btrfs_cow_block+0x163)[0x408eb7]
./mkfs.btrfs(btrfs_cow_block+0xd0)[0x4097c4]
./mkfs.btrfs(btrfs_search_slot+0x16f)[0x40be4d]
./mkfs.btrfs(btrfs_insert_empty_items+0xc0)[0x40d5f9]
./mkfs.btrfs(btrfs_insert_item+0x99)[0x40da5f]
./mkfs.btrfs(btrfs_make_block_group+0x4d)[0x41705c]
./mkfs.btrfs(main+0xeef)[0x434b56]

CC: Qu Wenruo <quwenruo@cn.fujitsu.com>
Signed-off-by: David Sterba <dsterba@suse.com>
---
 volumes.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/volumes.h b/volumes.h
index f7761311e8ce..4ecb99314a0c 100644
--- a/volumes.h
+++ b/volumes.h
@@ -156,7 +156,7 @@ struct map_lookup {
 static inline int check_crossing_stripes(u64 start, u64 len)
 {
 	return (start / BTRFS_STRIPE_LEN) !=
-	       ((start + len) / BTRFS_STRIPE_LEN);
+	       ((start + len - 1) / BTRFS_STRIPE_LEN);
 }
 
 int __btrfs_map_block(struct btrfs_mapping_tree *map_tree, int rw,
-- 
2.1.3