md: use bdev_nr_sectors instead of open coding it

Use the proper helper to read the block device size.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NKees Cook <keescook@chromium.org>
Acked-by: NSong Liu <song@kernel.org>
Link: https://lore.kernel.org/r/20211018101130.1838532-7-hch@lst.deSigned-off-by: NJens Axboe <axboe@kernel.dk>

drivers/md/md.c

@@ -888,8 +888,7 @@ static struct md_personality *find_pers(int level, char *clevel)
 /* return the offset of the super block in 512byte sectors */
 static inline sector_t calc_dev_sboffset(struct md_rdev *rdev)
 {
-	sector_t num_sectors = i_size_read(rdev->bdev->bd_inode) / 512;
-	return MD_NEW_SIZE_SECTORS(num_sectors);
+	return MD_NEW_SIZE_SECTORS(bdev_nr_sectors(rdev->bdev));
 }
 
 static int alloc_disk_sb(struct md_rdev *rdev)
@@ -1631,8 +1630,7 @@ static int super_1_load(struct md_rdev *rdev, struct md_rdev *refdev, int minor_
 	 */
 	switch(minor_version) {
 	case 0:
-		sb_start = i_size_read(rdev->bdev->bd_inode) >> 9;
-		sb_start -= 8*2;
+		sb_start = bdev_nr_sectors(rdev->bdev) - 8 * 2;
 		sb_start &= ~(sector_t)(4*2-1);
 		break;
 	case 1:
@@ -1787,10 +1785,9 @@ static int super_1_load(struct md_rdev *rdev, struct md_rdev *refdev, int minor_
 		else
 			ret = 0;
 	}
-	if (minor_version) {
-		sectors = (i_size_read(rdev->bdev->bd_inode) >> 9);
-		sectors -= rdev->data_offset;
-	} else
+	if (minor_version)
+		sectors = bdev_nr_sectors(rdev->bdev) - rdev->data_offset;
+	else
 		sectors = rdev->sb_start;
 	if (sectors < le64_to_cpu(sb->data_size))
 		return -EINVAL;
@@ -2168,8 +2165,7 @@ super_1_rdev_size_change(struct md_rdev *rdev, sector_t num_sectors)
 		return 0; /* too confusing */
 	if (rdev->sb_start < rdev->data_offset) {
 		/* minor versions 1 and 2; superblock before data */
-		max_sectors = i_size_read(rdev->bdev->bd_inode) >> 9;
-		max_sectors -= rdev->data_offset;
+		max_sectors = bdev_nr_sectors(rdev->bdev) - rdev->data_offset;
 		if (!num_sectors || num_sectors > max_sectors)
 			num_sectors = max_sectors;
 	} else if (rdev->mddev->bitmap_info.offset) {
@@ -2178,7 +2174,7 @@ super_1_rdev_size_change(struct md_rdev *rdev, sector_t num_sectors)
 	} else {
 		/* minor version 0; superblock after data */
 		sector_t sb_start, bm_space;
-		sector_t dev_size = i_size_read(rdev->bdev->bd_inode) >> 9;
+		sector_t dev_size = bdev_nr_sectors(rdev->bdev);
 
 		/* 8K is for superblock */
 		sb_start = dev_size - 8*2;
@@ -3382,7 +3378,7 @@ rdev_size_store(struct md_rdev *rdev, const char *buf, size_t len)
 			if (!sectors)
 				return -EBUSY;
 		} else if (!sectors)
-			sectors = (i_size_read(rdev->bdev->bd_inode) >> 9) -
+			sectors = bdev_nr_sectors(rdev->bdev) -
 				rdev->data_offset;
 		if (!my_mddev->pers->resize)
 			/* Cannot change size for RAID0 or Linear etc */
@@ -3709,7 +3705,7 @@ static struct md_rdev *md_import_device(dev_t newdev, int super_format, int supe
 
 	kobject_init(&rdev->kobj, &rdev_ktype);
 
-	size = i_size_read(rdev->bdev->bd_inode) >> BLOCK_SIZE_BITS;
+	size = bdev_nr_bytes(rdev->bdev) >> BLOCK_SIZE_BITS;
 	if (!size) {
 		pr_warn("md: %s has zero or unknown size, marking faulty!\n",
 			bdevname(rdev->bdev,b));
@@ -6880,7 +6876,7 @@ int md_add_new_disk(struct mddev *mddev, struct mdu_disk_info_s *info)
 
 		if (!mddev->persistent) {
 			pr_debug("md: nonpersistent superblock ...\n");
-			rdev->sb_start = i_size_read(rdev->bdev->bd_inode) / 512;
+			rdev->sb_start = bdev_nr_sectors(rdev->bdev);
 		} else
 			rdev->sb_start = calc_dev_sboffset(rdev);
 		rdev->sectors = rdev->sb_start;
@@ -6967,7 +6963,7 @@ static int hot_add_disk(struct mddev *mddev, dev_t dev)
 	if (mddev->persistent)
 		rdev->sb_start = calc_dev_sboffset(rdev);
 	else
-		rdev->sb_start = i_size_read(rdev->bdev->bd_inode) / 512;
+		rdev->sb_start = bdev_nr_sectors(rdev->bdev);
 
 	rdev->sectors = rdev->sb_start;