fs/affs: make root lookup from blkdev logical size

This patch resolves https://bugzilla.kernel.org/show_bug.cgi?id=16531.

When logical blkdev size > 512 then sector numbers become larger than the
device can support.

Make affs start lookup based on the device's logical sector size instead
of 512.

Reported-by: Mark <[e-mail]>
Suggested-by: Mark <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

fs/affs/super.c

···
 #include <linux/sched.h>
 #include <linux/slab.h>
 #include <linux/writeback.h>
+#include <linux/blkdev.h>
 #include "affs.h"
 
 static int affs_statfs(struct dentry *dentry, struct kstatfs *buf);
···
 	 * blocks, we will have to change it.
 	 */
 
-	size = sb->s_bdev->bd_inode->i_size >> 9;
+	size = i_size_read(sb->s_bdev->bd_inode) >> 9;
 	pr_debug("initial blocksize=%d, #blocks=%d\n", 512, size);
 
 	affs_set_blocksize(sb, PAGE_SIZE);
 	/* Try to find root block. Its location depends on the block size. */
 
-	i = 512;
-	j = 4096;
+	i = bdev_logical_block_size(sb->s_bdev);
+	j = PAGE_SIZE;
 	if (blocksize > 0) {
 		i = j = blocksize;
 		size = size / (blocksize / 512);
 	}
+
 	for (blocksize = i; blocksize <= j; blocksize <<= 1, size >>= 1) {
 		sbi->s_root_block = root_block;
 		if (root_block < 0)