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, 6 deletions

diff --git a/fs/btrfs/compression.c b/fs/btrfs/compression.c
index 1daea0b47187..eeee13842cd0 100644
--- a/fs/btrfs/compression.c
+++ b/fs/btrfs/compression.c
@@ -91,8 +91,7 @@ static inline int compressed_bio_size(struct btrfs_root *root,
         u16 csum_size = btrfs_super_csum_size(root->fs_info->super_copy);
 
         return sizeof(struct compressed_bio) +
-                ((disk_size + root->sectorsize - 1) / root->sectorsize) *
-                csum_size;
+                (DIV_ROUND_UP(disk_size, root->sectorsize)) * csum_size;
 }
 
 static struct bio *compressed_bio_alloc(struct block_device *bdev,
@@ -615,8 +614,7 @@ int btrfs_submit_compressed_read(struct inode *inode, struct bio *bio,
         cb->compress_type = extent_compress_type(bio_flags);
         cb->orig_bio = bio;
 
-        nr_pages = (compressed_len + PAGE_CACHE_SIZE - 1) /
-                                 PAGE_CACHE_SIZE;
+        nr_pages = DIV_ROUND_UP(compressed_len, PAGE_CACHE_SIZE);
         cb->compressed_pages = kzalloc(sizeof(struct page *) * nr_pages,
                                        GFP_NOFS);
         if (!cb->compressed_pages)
@@ -686,8 +684,8 @@ int btrfs_submit_compressed_read(struct inode *inode, struct bio *bio,
                                                         comp_bio, sums);
                                 BUG_ON(ret); /* -ENOMEM */
                         }
-                        sums += (comp_bio->bi_iter.bi_size +
-                                 root->sectorsize - 1) / root->sectorsize;
+                        sums += DIV_ROUND_UP(comp_bio->bi_iter.bi_size,
+                                             root->sectorsize);
 
                         ret = btrfs_map_bio(root, READ, comp_bio,
                                             mirror_num, 0);