Btrfs: convert printk to btrfs_ and fix BTRFS prefix

Convert all applicable cases of printk and pr_* to the btrfs_* macros.

Fix all uses of the BTRFS prefix.

Signed-off-by: Frank Holton <fholton@gmail.com>
Signed-off-by: Josef Bacik <jbacik@fb.com>
Signed-off-by: Chris Mason <clm@fb.com>
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 2ccf8e6..06bcf5b 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -6966,8 +6966,8 @@
 	struct btrfs_dio_private *dip = bio->bi_private;
 
 	if (err) {
-		printk(KERN_ERR "btrfs direct IO failed ino %llu rw %lu "
-		      "sector %#Lx len %u err no %d\n",
+		btrfs_err(BTRFS_I(dip->inode)->root->fs_info,
+			  "direct IO failed ino %llu rw %lu sector %#Lx len %u err no %d",
 		      btrfs_ino(dip->inode), bio->bi_rw,
 		      (unsigned long long)bio->bi_sector, bio->bi_size, err);
 		dip->errors = 1;