Commit e3bb2e30 authored by Alex Elder's avatar Alex Elder
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xfs: avoid repeated pointer dereferences 



In xlog_find_cycle_start() use a local variable for some repeated
operations rather than constantly accessing the memory location
whose address is passed in.

(This version drops an assertion that a pointer is non-null.)

Signed-off-by: default avatarAlex Elder <aelder@sgi.com>
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
parent 9db127ed

fs/xfs/xfs_log_recover.c

+13 −12
Original line number Diff line number Diff line
@@ -354,26 +354,27 @@ xlog_find_cycle_start( 
{

	xfs_caddr_t	offset;

	xfs_daddr_t	mid_blk;

	xfs_daddr_t	end_blk;

	uint		mid_cycle;

	int		error;



	mid_blk = BLK_AVG(first_blk, *last_blk);

	while (mid_blk != first_blk && mid_blk != *last_blk) {

	end_blk = *last_blk;

	mid_blk = BLK_AVG(first_blk, end_blk);

	while (mid_blk != first_blk && mid_blk != end_blk) {

		error = xlog_bread(log, mid_blk, 1, bp, &offset);

		if (error)

			return error;

		mid_cycle = xlog_get_cycle(offset);

		if (mid_cycle == cycle) {

			*last_blk = mid_blk;

			/* last_half_cycle == mid_cycle */

		} else {

			first_blk = mid_blk;

			/* first_half_cycle == mid_cycle */

		}

		mid_blk = BLK_AVG(first_blk, *last_blk);

		if (mid_cycle == cycle)

			end_blk = mid_blk;   /* last_half_cycle == mid_cycle */

		else

			first_blk = mid_blk; /* first_half_cycle == mid_cycle */

		mid_blk = BLK_AVG(first_blk, end_blk);

	}

	ASSERT((mid_blk == first_blk && mid_blk+1 == *last_blk) ||

	       (mid_blk == *last_blk && mid_blk-1 == first_blk));

	ASSERT((mid_blk == first_blk && mid_blk+1 == end_blk) ||

	       (mid_blk == end_blk && mid_blk-1 == first_blk));



	*last_blk = end_blk;



	return 0;

}