[PATCH 1/3] btrfs: simplify counting number of eb pages

[David Sterba <dsterba@suse.com>]

The eb length is nodesize, as initialized in __alloc_extent_buffer.
Regardless of start, we should always get the same number of pages, so
use that fact.

Signed-off-by: David Sterba <dsterba@suse.com>
---
 fs/btrfs/extent_io.h | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/fs/btrfs/extent_io.h b/fs/btrfs/extent_io.h
index a53009694b16..ee92c1289edd 100644
--- a/fs/btrfs/extent_io.h
+++ b/fs/btrfs/extent_io.h
@@ -454,8 +454,7 @@ void wait_on_extent_buffer_writeback(struct extent_buffer *eb);
 
 static inline unsigned long num_extent_pages(u64 start, u64 len)
 {
-	return ((start + len + PAGE_SIZE - 1) >> PAGE_SHIFT) -
-		(start >> PAGE_SHIFT);
+	return len >> PAGE_SHIFT;
 }
 
 static inline void extent_buffer_get(struct extent_buffer *eb)
-- 
2.16.2