fs: btrfs: Crossport volumes.[ch] from btrfs-progs

This patch crossports volumes.[ch] from btrfs-progs, including:
- btrfs_map_block()
  The core mechanism to map btrfs logical address to physical address.
  This version includes multi-device support, along with RAID56 support.

- btrfs_scan_one_device()
  This is the function to register one btrfs device to the list.
  This is the main part of the multi-device btrfs assembling process.
  Although we're not going to support multiple devices until U-Boot
  allows us to scan one device without actually opening it.

Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: Marek Behún <marek.behun@nic.cz>
[trini: Use %zu in a debug print to avoid warning]
Signed-off-by: Tom Rini <trini@konsulko.com>

1 files changed, 5 insertions, 0 deletions

diff --git a/fs/btrfs/compat.h b/fs/btrfs/compat.h
index 12fb9f8..be4f4e7 100644
--- a/fs/btrfs/compat.h
+++ b/fs/btrfs/compat.h
@@ -68,4 +68,9 @@ static inline void uuid_unparse(const u8 *uuid, char *out)
 	return uuid_bin_to_str((unsigned char *)uuid, out, 0);
 }
 
+static inline int is_power_of_2(unsigned long n)
+{
+	return (n != 0 && ((n & (n - 1)) == 0));
+}
+
 #endif