ext4: rename ext4_claim_free_blocks() to ext4_claim_free_clusters()

This function really claims a number of free clusters, not blocks, so
rename it so it's clearer what's going on.

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index f9198d7..557c34f 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -1071,7 +1071,7 @@
 	 * We do still charge estimated metadata to the sb though;
 	 * we cannot afford to run out of free blocks.
 	 */
-	if (ext4_claim_free_blocks(sbi, md_needed + 1, 0)) {
+	if (ext4_claim_free_clusters(sbi, md_needed + 1, 0)) {
 		dquot_release_reservation_block(inode, EXT4_C2B(sbi, 1));
 		if (ext4_should_retry_alloc(inode->i_sb, &retries)) {
 			yield();