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>

fs/btrfs/check-integrity.c

@@ -1251,8 +1251,7 @@ static void btrfsic_read_from_block_data(
 
 	while (len > 0) {
 		cur = min(len, ((size_t)PAGE_CACHE_SIZE - offset_in_page));
-		BUG_ON(i >= (block_ctx->len + PAGE_CACHE_SIZE - 1) >>
-			    PAGE_CACHE_SHIFT);
+		BUG_ON(i >= DIV_ROUND_UP(block_ctx->len, PAGE_CACHE_SIZE));
 		kaddr = block_ctx->datav[i];
 		memcpy(dst, kaddr + offset_in_page, cur);
 

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);

fs/btrfs/file.c

@@ -1481,9 +1481,8 @@ static noinline ssize_t __btrfs_buffered_write(struct file *file,
 	bool force_page_uptodate = false;
 	bool need_unlock;
 
-	nrptrs = min((iov_iter_count(i) + PAGE_CACHE_SIZE - 1) /
-		     PAGE_CACHE_SIZE, PAGE_CACHE_SIZE /
-		     (sizeof(struct page *)));
+	nrptrs = min(DIV_ROUND_UP(iov_iter_count(i), PAGE_CACHE_SIZE),
+			PAGE_CACHE_SIZE / (sizeof(struct page *)));
 	nrptrs = min(nrptrs, current->nr_dirtied_pause - current->nr_dirtied);
 	nrptrs = max(nrptrs, 8);
 	pages = kmalloc(nrptrs * sizeof(struct page *), GFP_KERNEL);
@@ -1497,8 +1496,8 @@ static noinline ssize_t __btrfs_buffered_write(struct file *file,
 		size_t write_bytes = min(iov_iter_count(i),
 					 nrptrs * (size_t)PAGE_CACHE_SIZE -
 					 offset);
-		size_t num_pages = (write_bytes + offset +
-				    PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
+		size_t num_pages = DIV_ROUND_UP(write_bytes + offset,
+						PAGE_CACHE_SIZE);
 		size_t reserve_bytes;
 		size_t dirty_pages;
 		size_t copied;
@@ -1526,9 +1525,8 @@ static noinline ssize_t __btrfs_buffered_write(struct file *file,
 				 * our prealloc extent may be smaller than
 				 * write_bytes, so scale down.
 				 */
-				num_pages = (write_bytes + offset +
-					     PAGE_CACHE_SIZE - 1) >>
-					PAGE_CACHE_SHIFT;
+				num_pages = DIV_ROUND_UP(write_bytes + offset,
+							 PAGE_CACHE_SIZE);
 				reserve_bytes = num_pages << PAGE_CACHE_SHIFT;
 				ret = 0;
 			} else {
@@ -1590,9 +1588,8 @@ static noinline ssize_t __btrfs_buffered_write(struct file *file,
 			dirty_pages = 0;
 		} else {
 			force_page_uptodate = false;
-			dirty_pages = (copied + offset +
-				       PAGE_CACHE_SIZE - 1) >>
-				       PAGE_CACHE_SHIFT;
+			dirty_pages = DIV_ROUND_UP(copied + offset,
+						   PAGE_CACHE_SIZE);
 		}
 
 		/*

fs/btrfs/free-space-cache.c

@@ -279,8 +279,7 @@ static int io_ctl_init(struct io_ctl *io_ctl, struct inode *inode,
 	int num_pages;
 	int check_crcs = 0;
 
-	num_pages = (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >>
-		    PAGE_CACHE_SHIFT;
+	num_pages = DIV_ROUND_UP(i_size_read(inode), PAGE_CACHE_SIZE);
 
 	if (btrfs_ino(inode) != BTRFS_FREE_INO_OBJECTID)
 		check_crcs = 1;

fs/btrfs/ioctl.c

@@ -1335,8 +1335,7 @@ int btrfs_defrag_file(struct inode *inode, struct file *file,
 		inode->i_mapping->writeback_index = i;
 
 	while (i <= last_index && defrag_count < max_to_defrag &&
-	       (i < (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >>
-		PAGE_CACHE_SHIFT)) {
+	       (i < DIV_ROUND_UP(i_size_read(inode), PAGE_CACHE_SIZE))) {
 		/*
 		 * make sure we stop running if someone unmounts
 		 * the FS
@@ -1359,7 +1358,7 @@ int btrfs_defrag_file(struct inode *inode, struct file *file,
 			 * the should_defrag function tells us how much to skip
 			 * bump our counter by the suggested amount
 			 */
-			next = (skip + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
+			next = DIV_ROUND_UP(skip, PAGE_CACHE_SIZE);
 			i = max(i + 1, next);
 			continue;
 		}

fs/btrfs/lzo.c

@@ -266,8 +266,7 @@ static int lzo_decompress_biovec(struct list_head *ws,
 	char *data_in;
 	unsigned long page_in_index = 0;
 	unsigned long page_out_index = 0;
-	unsigned long total_pages_in = (srclen + PAGE_CACHE_SIZE - 1) /
-					PAGE_CACHE_SIZE;
+	unsigned long total_pages_in = DIV_ROUND_UP(srclen, PAGE_CACHE_SIZE);
 	unsigned long buf_start;
 	unsigned long buf_offset = 0;
 	unsigned long bytes;

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;

fs/btrfs/zlib.c

@@ -225,8 +225,7 @@ static int zlib_decompress_biovec(struct list_head *ws, struct page **pages_in,
 	size_t total_out = 0;
 	unsigned long page_in_index = 0;
 	unsigned long page_out_index = 0;
-	unsigned long total_pages_in = (srclen + PAGE_CACHE_SIZE - 1) /
-					PAGE_CACHE_SIZE;
+	unsigned long total_pages_in = DIV_ROUND_UP(srclen, PAGE_CACHE_SIZE);
 	unsigned long buf_start;
 	unsigned long pg_offset;