[PATCH] md: only calculate blocksize once and use i_blocksize()

[Xianting Tian]

We alreday has the interface i_blocksize(), which can be used
to get blocksize, so use it.
Only calculate blocksize once and use it within read_page().

Signed-off-by: Xianting Tian <tian.xiant...@h3c.com>
---
 drivers/md/md-bitmap.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/drivers/md/md-bitmap.c b/drivers/md/md-bitmap.c
index 95a5f3757..0d5544868 100644
--- a/drivers/md/md-bitmap.c
+++ b/drivers/md/md-bitmap.c
@@ -357,11 +357,12 @@ static int read_page(struct file *file, unsigned long 
index,
        struct inode *inode = file_inode(file);
        struct buffer_head *bh;
        sector_t block, blk_cur;
+       unsigned long blocksize = i_blocksize(inode);
 
        pr_debug("read bitmap file (%dB @ %llu)\n", (int)PAGE_SIZE,
                 (unsigned long long)index << PAGE_SHIFT);
 
-       bh = alloc_page_buffers(page, 1<<inode->i_blkbits, false);
+       bh = alloc_page_buffers(page, blocksize, false);
        if (!bh) {
                ret = -ENOMEM;
                goto out;
@@ -383,10 +384,10 @@ static int read_page(struct file *file, unsigned long 
index,
 
                        bh->b_blocknr = block;
                        bh->b_bdev = inode->i_sb->s_bdev;
-                       if (count < (1<<inode->i_blkbits))
+                       if (count < blocksize)
                                count = 0;
                        else
-                               count -= (1<<inode->i_blkbits);
+                               count -= blocksize;
 
                        bh->b_end_io = end_bitmap_write;
                        bh->b_private = bitmap;
-- 
2.17.1