fs: add i_blocksize()

Replace all 1 << inode->i_blkbits and (1 << inode->i_blkbits) in fs
branch.

This patch also fixes multiple checkpatch warnings: WARNING: Prefer
'unsigned int' to bare use of 'unsigned'

Thanks to Andrew Morton for suggesting more appropriate function instead
of macro.

[geliangtang@gmail.com: truncate: use i_blocksize()]
  Link: http://lkml.kernel.org/r/9c8b2cd83c8f5653805d43debde9fa8817e02fc4.1484895804.git.geliangtang@gmail.com
Link: http://lkml.kernel.org/r/1481319905-10126-1-git-send-email-fabf@skynet.be
Signed-off-by: Fabian Frederick <fabf@skynet.be>
Signed-off-by: Geliang Tang <geliangtang@gmail.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/fs/buffer.c b/fs/buffer.c
index 0e87401..28484b3 100644
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -2395,7 +2395,7 @@ static int cont_expand_zero(struct file *file, struct address_space *mapping,
 			    loff_t pos, loff_t *bytes)
 {
 	struct inode *inode = mapping->host;
-	unsigned blocksize = 1 << inode->i_blkbits;
+	unsigned int blocksize = i_blocksize(inode);
 	struct page *page;
 	void *fsdata;
 	pgoff_t index, curidx;
@@ -2475,8 +2475,8 @@ int cont_write_begin(struct file *file, struct address_space *mapping,
 			get_block_t *get_block, loff_t *bytes)
 {
 	struct inode *inode = mapping->host;
-	unsigned blocksize = 1 << inode->i_blkbits;
-	unsigned zerofrom;
+	unsigned int blocksize = i_blocksize(inode);
+	unsigned int zerofrom;
 	int err;
 
 	err = cont_expand_zero(file, mapping, pos, bytes);
@@ -2838,7 +2838,7 @@ int nobh_truncate_page(struct address_space *mapping,
 	struct buffer_head map_bh;
 	int err;
 
-	blocksize = 1 << inode->i_blkbits;
+	blocksize = i_blocksize(inode);
 	length = offset & (blocksize - 1);
 
 	/* Block boundary? Nothing to do */
@@ -2916,7 +2916,7 @@ int block_truncate_page(struct address_space *mapping,
 	struct buffer_head *bh;
 	int err;
 
-	blocksize = 1 << inode->i_blkbits;
+	blocksize = i_blocksize(inode);
 	length = offset & (blocksize - 1);
 
 	/* Block boundary? Nothing to do */
@@ -3028,7 +3028,7 @@ sector_t generic_block_bmap(struct address_space *mapping, sector_t block,
 	struct inode *inode = mapping->host;
 	tmp.b_state = 0;
 	tmp.b_blocknr = 0;
-	tmp.b_size = 1 << inode->i_blkbits;
+	tmp.b_size = i_blocksize(inode);
 	get_block(inode, block, &tmp, 0);
 	return tmp.b_blocknr;
 }