btrfs: sink blocksize parameter to btrfs_find_create_tree_block

Finally it's clear that the requested blocksize is always equal to
nodesize, with one exception, the superblock.

Superblock has fixed size regardless of the metadata block size, but
uses the same helpers to initialize sys array/chunk tree and to work
with the chunk items. So it pretends to be an extent_buffer for a
moment, btrfs_read_sys_array is full of special cases, we're adding one
more.

Signed-off-by: David Sterba <dsterba@suse.cz>

1 files changed, 7 insertions, 2 deletions

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 0144790e296e..f0af9cd0814c 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -6247,8 +6247,13 @@ int btrfs_read_sys_array(struct btrfs_root *root)
 	u32 cur;
 	struct btrfs_key key;
 
-	sb = btrfs_find_create_tree_block(root, BTRFS_SUPER_INFO_OFFSET,
-					  BTRFS_SUPER_INFO_SIZE);
+	ASSERT(BTRFS_SUPER_INFO_SIZE <= root->nodesize);
+	/*
+	 * This will create extent buffer of nodesize, superblock size is
+	 * fixed to BTRFS_SUPER_INFO_SIZE. If nodesize > sb size, this will
+	 * overallocate but we can keep it as-is, only the first page is used.
+	 */
+	sb = btrfs_find_create_tree_block(root, BTRFS_SUPER_INFO_OFFSET);
 	if (!sb)
 		return -ENOMEM;
 	btrfs_set_buffer_uptodate(sb);