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/xfs/xfs_file.c b/fs/xfs/xfs_file.c
index a50eca6..35703a8 100644
--- a/fs/xfs/xfs_file.c
+++ b/fs/xfs/xfs_file.c
@@ -754,7 +754,7 @@ xfs_file_fallocate(
 		if (error)
 			goto out_unlock;
 	} else if (mode & FALLOC_FL_COLLAPSE_RANGE) {
-		unsigned blksize_mask = (1 << inode->i_blkbits) - 1;
+		unsigned int blksize_mask = i_blocksize(inode) - 1;
 
 		if (offset & blksize_mask || len & blksize_mask) {
 			error = -EINVAL;
@@ -776,7 +776,7 @@ xfs_file_fallocate(
 		if (error)
 			goto out_unlock;
 	} else if (mode & FALLOC_FL_INSERT_RANGE) {
-		unsigned blksize_mask = (1 << inode->i_blkbits) - 1;
+		unsigned int blksize_mask = i_blocksize(inode) - 1;
 
 		new_size = i_size_read(inode) + len;
 		if (offset & blksize_mask || len & blksize_mask) {