ext4: use BIT() macro for BH_** state bits

Simply use BIT() macro for all BH_** state bits instead of open
coding it.

There should be no functionality change in this patch.

Signed-off-by: Ritesh Harjani <riteshh@linux.ibm.com>
Link: https://lore.kernel.org/r/57667689f51a3f9dba2fcef7d3425187fa3ba69f.1589086800.git.riteshh@linux.ibm.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

fs/ext4/ext4.h

@@ -171,10 +171,10 @@ struct ext4_allocation_request {
  * well as to store the information returned by ext4_map_blocks().  It
  * takes less room on the stack than a struct buffer_head.
  */
-#define EXT4_MAP_NEW		(1 << BH_New)
-#define EXT4_MAP_MAPPED		(1 << BH_Mapped)
-#define EXT4_MAP_UNWRITTEN	(1 << BH_Unwritten)
-#define EXT4_MAP_BOUNDARY	(1 << BH_Boundary)
+#define EXT4_MAP_NEW		BIT(BH_New)
+#define EXT4_MAP_MAPPED		BIT(BH_Mapped)
+#define EXT4_MAP_UNWRITTEN	BIT(BH_Unwritten)
+#define EXT4_MAP_BOUNDARY	BIT(BH_Boundary)
 #define EXT4_MAP_FLAGS		(EXT4_MAP_NEW | EXT4_MAP_MAPPED |\
 				 EXT4_MAP_UNWRITTEN | EXT4_MAP_BOUNDARY)
 

fs/ext4/inode.c

@@ -2084,7 +2084,7 @@ static int mpage_submit_page(struct mpage_da_data *mpd, struct page *page)
 	return err;
 }
 
-#define BH_FLAGS ((1 << BH_Unwritten) | (1 << BH_Delay))
+#define BH_FLAGS (BIT(BH_Unwritten) | BIT(BH_Delay))
 
 /*
  * mballoc gives us at most this number of blocks...
@@ -2364,7 +2364,7 @@ static int mpage_map_one_extent(handle_t *handle, struct mpage_da_data *mpd)
 	dioread_nolock = ext4_should_dioread_nolock(inode);
 	if (dioread_nolock)
 		get_blocks_flags |= EXT4_GET_BLOCKS_IO_CREATE_EXT;
-	if (map->m_flags & (1 << BH_Delay))
+	if (map->m_flags & BIT(BH_Delay))
 		get_blocks_flags |= EXT4_GET_BLOCKS_DELALLOC_RESERVE;
 
 	err = ext4_map_blocks(handle, inode, map, get_blocks_flags);