Btrfs: remove repeated eb->pages check in, disk-io.c/csum_dirty_buffer

In csum_dirty_buffer, we first get eb from page->private. Then we check if the page is the first page of eb. Later we check it again. Remove the repeated check here.

---
 fs/btrfs/disk-io.c |    8 +++-----
 1 files changed, 3 insertions(+), 5 deletions(-)

index 22e98e0..8919c56 100644
@@ -432,14 +432,12 @@ static int csum_dirty_buffer(struct btrfs_root *root, struct page *page)
 	tree = &BTRFS_I(page->mapping->host)->io_tree;
 
 	eb = (struct extent_buffer *)page->private;
-	if (page != eb->pages[0])
-		return 0;
-	found_start = btrfs_header_bytenr(eb);
-	if (found_start != start) {
+	if (page != eb->pages[0]) {
 		WARN_ON(1);
 		return 0;
 	}
-	if (eb->pages[0] != page) {
+	found_start = btrfs_header_bytenr(eb);
+	if (found_start != start) {
 		WARN_ON(1);
 		return 0;
 	}

1.7.5.4

You had the right idea here, two checks and one has a warning, so you kept the warning. But when the metadata block size is bigger than a page, the WARN_ON triggers for any page that isn't the first one in the extent buffer.

I kept this commit but removed the WARN_ON(1)

-chris