btrfs: use bdev_nr_bytes instead of open coding it

Use the proper helper to read the block device size.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>
Acked-by: David Sterba <dsterba@suse.com>
Link: https://lore.kernel.org/r/20211018101130.1838532-13-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>

fs/btrfs/dev-replace.c

@@ -283,8 +283,7 @@ static int btrfs_init_dev_replace_tgtdev(struct btrfs_fs_info *fs_info,
 	}
 
 
-	if (i_size_read(bdev->bd_inode) <
-	    btrfs_device_get_total_bytes(srcdev)) {
+	if (bdev_nr_bytes(bdev) < btrfs_device_get_total_bytes(srcdev)) {
 		btrfs_err(fs_info,
 			  "target device is smaller than source device!");
 		ret = -EINVAL;

fs/btrfs/disk-io.c

@@ -3740,7 +3740,7 @@ struct btrfs_super_block *btrfs_read_dev_one_super(struct block_device *bdev,
 	else if (ret)
 		return ERR_PTR(ret);
 
-	if (bytenr + BTRFS_SUPER_INFO_SIZE >= i_size_read(bdev->bd_inode))
+	if (bytenr + BTRFS_SUPER_INFO_SIZE >= bdev_nr_bytes(bdev))
 		return ERR_PTR(-EINVAL);
 
 	page = read_cache_page_gfp(mapping, bytenr >> PAGE_SHIFT, GFP_NOFS);

fs/btrfs/ioctl.c

@@ -1730,7 +1730,7 @@ static noinline int btrfs_ioctl_resize(struct file *file,
 	}
 
 	if (!strcmp(sizestr, "max"))
-		new_size = device->bdev->bd_inode->i_size;
+		new_size = bdev_nr_bytes(device->bdev);
 	else {
 		if (sizestr[0] == '-') {
 			mod = -1;
@@ -1771,7 +1771,7 @@ static noinline int btrfs_ioctl_resize(struct file *file,
 		ret = -EINVAL;
 		goto out_finish;
 	}
-	if (new_size > device->bdev->bd_inode->i_size) {
+	if (new_size > bdev_nr_bytes(device->bdev)) {
 		ret = -EFBIG;
 		goto out_finish;
 	}

fs/btrfs/volumes.c

@@ -1286,7 +1286,7 @@ static struct btrfs_super_block *btrfs_read_disk_super(struct block_device *bdev
 	pgoff_t index;
 
 	/* make sure our super fits in the device */
-	if (bytenr + PAGE_SIZE >= i_size_read(bdev->bd_inode))
+	if (bytenr + PAGE_SIZE >= bdev_nr_bytes(bdev))
 		return ERR_PTR(-EINVAL);
 
 	/* make sure our super fits in the page */
@@ -2610,8 +2610,8 @@ int btrfs_init_new_device(struct btrfs_fs_info *fs_info, const char *device_path
 	device->io_width = fs_info->sectorsize;
 	device->io_align = fs_info->sectorsize;
 	device->sector_size = fs_info->sectorsize;
-	device->total_bytes = round_down(i_size_read(bdev->bd_inode),
-					 fs_info->sectorsize);
+	device->total_bytes =
+		round_down(bdev_nr_bytes(bdev), fs_info->sectorsize);
 	device->disk_total_bytes = device->total_bytes;
 	device->commit_total_bytes = device->total_bytes;
 	set_bit(BTRFS_DEV_STATE_IN_FS_METADATA, &device->dev_state);
@@ -7236,7 +7236,7 @@ static int read_one_dev(struct extent_buffer *leaf,
 
 	fill_device_from_item(leaf, dev_item, device);
 	if (device->bdev) {
-		u64 max_total_bytes = i_size_read(device->bdev->bd_inode);
+		u64 max_total_bytes = bdev_nr_bytes(device->bdev);
 
 		if (device->total_bytes > max_total_bytes) {
 			btrfs_err(fs_info,