Commit f2a3717a authored by Christoph Hellwig's avatar Christoph Hellwig Committed by Carlos Maiolino
Browse files

xfs: add a fast path to xfs_buf_zero when b_addr is set 



No need to walk the page list if bp->b_addr is valid.  That also means
b_offset doesn't need to be taken into account in the unmapped loop as
b_offset is only set for kmem backed buffers which are always mapped.

Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
Reviewed-by: default avatarDarrick J. Wong <djwong@kernel.org>
Signed-off-by: default avatarCarlos Maiolino <cem@kernel.org>
parent 69659e46

fs/xfs/xfs_buf.c

+7 −2
Original line number Diff line number Diff line
@@ -1633,13 +1633,18 @@ xfs_buf_zero( 
{

	size_t			bend;



	if (bp->b_addr) {

		memset(bp->b_addr + boff, 0, bsize);

		return;

	}



	bend = boff + bsize;

	while (boff < bend) {

		struct page	*page;

		int		page_index, page_offset, csize;



		page_index = (boff + bp->b_offset) >> PAGE_SHIFT;

		page_offset = (boff + bp->b_offset) & ~PAGE_MASK;

		page_index = boff >> PAGE_SHIFT;

		page_offset = boff & ~PAGE_MASK;

		page = bp->b_pages[page_index];

		csize = min_t(size_t, PAGE_SIZE - page_offset,

				      BBTOB(bp->b_length) - boff);