btrfs: use DIV_ROUND_UP instead of open-coded variants

The form

  (value + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT

is equivalent to

  (value + PAGE_CACHE_SIZE - 1) / PAGE_CACHE_SIZE

The rest is a simple subsitution, no difference in the generated
assembly code.

Signed-off-by: David Sterba <dsterba@suse.cz>
Signed-off-by: Chris Mason <clm@fb.com>

1 files changed, 4 insertions, 4 deletions

diff --git a/fs/btrfs/raid56.c b/fs/btrfs/raid56.c
index 0a6b6e4bcbb9..6a41631cb959 100644
--- a/fs/btrfs/raid56.c
+++ b/fs/btrfs/raid56.c
@@ -912,7 +912,7 @@ static struct page *page_in_rbio(struct btrfs_raid_bio *rbio,
 static unsigned long rbio_nr_pages(unsigned long stripe_len, int nr_stripes)
 {
         unsigned long nr = stripe_len * nr_stripes;
-        return (nr + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
+        return DIV_ROUND_UP(nr, PAGE_CACHE_SIZE);
 }
 
 /*
@@ -1442,7 +1442,7 @@ static int raid56_rmw_stripe(struct btrfs_raid_bio *rbio)
         struct btrfs_bio *bbio = rbio->bbio;
         struct bio_list bio_list;
         int ret;
-        int nr_pages = (rbio->stripe_len + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
+        int nr_pages = DIV_ROUND_UP(rbio->stripe_len, PAGE_CACHE_SIZE);
         int pagenr;
         int stripe;
         struct bio *bio;
@@ -1725,7 +1725,7 @@ static void __raid_recover_end_io(struct btrfs_raid_bio *rbio)
         int pagenr, stripe;
         void **pointers;
         int faila = -1, failb = -1;
-        int nr_pages = (rbio->stripe_len + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
+        int nr_pages = DIV_ROUND_UP(rbio->stripe_len, PAGE_CACHE_SIZE);
         struct page *page;
         int err;
         int i;
@@ -1940,7 +1940,7 @@ static int __raid56_parity_recover(struct btrfs_raid_bio *rbio)
         struct btrfs_bio *bbio = rbio->bbio;
         struct bio_list bio_list;
         int ret;
-        int nr_pages = (rbio->stripe_len + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
+        int nr_pages = DIV_ROUND_UP(rbio->stripe_len, PAGE_CACHE_SIZE);
         int pagenr;
         int stripe;
         struct bio *bio;