Commit d549ff7b authored by David Sterba's avatar David Sterba
Browse files

btrfs: add helper for bit enumeration 



Define helper macro that can be used in enum {} to utilize the automatic
increment to define all bits without directly defining the values or
using additional linear bits.

1. capture the sequence value, N
2. use the value to define the given enum with N-th bit set
3. reset the sequence back to N

Use for enums that do not require fixed values for symbolic names (like
for on-disk structures):

enum {
	ENUM_BIT(FIRST),
	ENUM_BIT(SECOND),
	ENUM_BIT(THIRD)
};

Where the values would be 0x1, 0x2 and 0x4.

Reviewed-by: default avatarJosef Bacik <josef@toxicpanda.com>
Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
parent 5565b8e0

fs/btrfs/misc.h

+8 −0
Original line number Diff line number Diff line
@@ -10,6 +10,14 @@ 


#define in_range(b, first, len) ((b) >= (first) && (b) < (first) + (len))



/*

 * Enumerate bits using enum autoincrement. Define the @name as the n-th bit.

 */

#define ENUM_BIT(name)                                  \

	__ ## name ## _BIT,                             \

	name = (1U << __ ## name ## _BIT),              \

	__ ## name ## _SEQ = __ ## name ## _BIT



static inline void cond_wake_up(struct wait_queue_head *wq)

{

	/*