btrfs: convert pr_* to btrfs_* where possible

For many printks, we want to know which file system issued the message.

This patch converts most pr_* calls to use the btrfs_* versions instead.
In some cases, this means adding plumbing to allow call sites access to
an fs_info pointer.

fs/btrfs/check-integrity.c is left alone for another day.

Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
diff --git a/fs/btrfs/free-space-tree.c b/fs/btrfs/free-space-tree.c
index 1851bea..e4a42a8 100644
--- a/fs/btrfs/free-space-tree.c
+++ b/fs/btrfs/free-space-tree.c
@@ -107,7 +107,7 @@
 	if (ret < 0)
 		return ERR_PTR(ret);
 	if (ret != 0) {
-		btrfs_warn(fs_info, "missing free space info for %llu\n",
+		btrfs_warn(fs_info, "missing free space info for %llu",
 			   block_group->key.objectid);
 		ASSERT(0);
 		return ERR_PTR(-ENOENT);