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: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Carlos Maiolino <cem@kernel.org>
This commit is contained in:
Christoph Hellwig
2025-03-10 14:19:05 +01:00
committed by Carlos Maiolino
parent 69659e46b7
commit f2a3717a74

View File

@@ -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);