[PATCH 2/3] block: hoist block size validation code to a separate function

["Darrick J. Wong" <djwong@xxxxxxxxxx>]

From: Darrick J. Wong <djwong@xxxxxxxxxx>

Hoist the block size validation code to bdev_validate_blocksize so that
we can call it from filesystems that don't care about the bdev pagecache
manipulations of set_blocksize.

Signed-off-by: "Darrick J. Wong" <djwong@xxxxxxxxxx>
---
 include/linux/blkdev.h |    1 +
 block/bdev.c           |   33 +++++++++++++++++++++++++++------
 2 files changed, 28 insertions(+), 6 deletions(-)


diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 294bbae415aa09..462e23a1e8b261 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -1618,6 +1618,7 @@ static inline void bio_end_io_acct(struct bio *bio, unsigned long start_time)
 	return bio_end_io_acct_remapped(bio, start_time, bio->bi_bdev);
 }
 
+int bdev_validate_blocksize(struct block_device *bdev, int block_size);
 int set_blocksize(struct file *file, int size);
 
 int lookup_bdev(const char *pathname, dev_t *dev);
diff --git a/block/bdev.c b/block/bdev.c
index 24984ec13e7cb2..1588f96e4f0a35 100644
--- a/block/bdev.c
+++ b/block/bdev.c
@@ -152,17 +152,38 @@ static void set_init_blocksize(struct block_device *bdev)
 				    get_order(bsize), get_order(bsize));
 }
 
+/**
+ * bdev_validate_blocksize - check that this block size is acceptable
+ * @bdev:	blockdevice to check
+ * @block_size:	block size to check
+ *
+ * For block device users that do not use buffer heads or the block device
+ * page cache, make sure that this block size can be used with the device.
+ *
+ * Return: On success zero is returned, negative error code on failure.
+ */
+int bdev_validate_blocksize(struct block_device *bdev, int block_size)
+{
+	if (blk_validate_block_size(block_size))
+		return -EINVAL;
+
+	/* Size cannot be smaller than the size supported by the device */
+	if (block_size < bdev_logical_block_size(bdev))
+		return -EINVAL;
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(bdev_validate_blocksize);
+
 int set_blocksize(struct file *file, int size)
 {
 	struct inode *inode = file->f_mapping->host;
 	struct block_device *bdev = I_BDEV(inode);
+	int ret;
 
-	if (blk_validate_block_size(size))
-		return -EINVAL;
-
-	/* Size cannot be smaller than the size supported by the device */
-	if (size < bdev_logical_block_size(bdev))
-		return -EINVAL;
+	ret = bdev_validate_blocksize(bdev, size);
+	if (ret)
+		return ret;
 
 	if (!file->private_data)
 		return -EINVAL;