On Wed, Feb 26, 2025 at 07:51:30AM -0800, Christoph Hellwig wrote:
> 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@xxxxxx>
That's much clearer!
Reviewed-by: "Darrick J. Wong" <djwong@xxxxxxxxxx>
--D
> ---
> fs/xfs/xfs_buf.c | 9 +++++++--
> 1 file changed, 7 insertions(+), 2 deletions(-)
>
> diff --git a/fs/xfs/xfs_buf.c b/fs/xfs/xfs_buf.c
> index 15bb790359f8..9e0c64511936 100644
> --- a/fs/xfs/xfs_buf.c
> +++ b/fs/xfs/xfs_buf.c
> @@ -1688,13 +1688,18 @@ 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);
> --
> 2.45.2
>
>
