On Wed, May 19, 2021 at 09:08:53PM +0200, Christoph Hellwig wrote:
> Remove the check for an existing b_pages array as this function is always
> called right after allocating a buffer, so this can't happen. Also
> use kmem_zalloc to allocate the page array instead of doing a manual
> memset gіven that the inline array is already pre-zeroed as part of the
> freshly allocated buffer anyway.
>
> Signed-off-by: Christoph Hellwig <hch@xxxxxx>
> ---
> fs/xfs/xfs_buf.c | 23 +++++++++++------------
> 1 file changed, 11 insertions(+), 12 deletions(-)
>
> diff --git a/fs/xfs/xfs_buf.c b/fs/xfs/xfs_buf.c
> index 392b85d059bff5..9c64c374411081 100644
> --- a/fs/xfs/xfs_buf.c
> +++ b/fs/xfs/xfs_buf.c
> @@ -281,19 +281,18 @@ _xfs_buf_get_pages(
> struct xfs_buf *bp,
> int page_count)
> {
> - /* Make sure that we have a page list */
> - if (bp->b_pages == NULL) {
> - bp->b_page_count = page_count;
> - if (page_count <= XB_PAGES) {
> - bp->b_pages = bp->b_page_array;
> - } else {
> - bp->b_pages = kmem_alloc(sizeof(struct page *) *
> - page_count, KM_NOFS);
> - if (bp->b_pages == NULL)
> - return -ENOMEM;
> - }
> - memset(bp->b_pages, 0, sizeof(struct page *) * page_count);
> + ASSERT(bp->b_pages == NULL);
> +
> + bp->b_page_count = page_count;
> + if (page_count > XB_PAGES) {
> + bp->b_pages = kmem_zalloc(sizeof(struct page *) * page_count,
> + KM_NOFS);
> + if (!bp->b_pages)
> + return -ENOMEM;
> + } else {
> + bp->b_pages = bp->b_page_array;
> }
> +
> return 0;
> }
This will not apply (and break) the bulk alloc patch I sent out - we
have to ensure that the b_pages array is always zeroed before we
call the bulk alloc function, hence I moved the memset() in this
function to be unconditional. I almost cleaned up this function in
that patchset....
Just doing this:
bp->b_page_count = page_count;
if (page_count > XB_PAGES) {
bp->b_pages = kmem_alloc(sizeof(struct page *) * page_count,
KM_NOFS);
if (!bp->b_pages)
return -ENOMEM;
} else {
bp->b_pages = bp->b_page_array;
}
memset(bp->b_pages, 0, sizeof(struct page *) * page_count);
return 0;
will make it work fine with bulk alloc.
Cheers,
Dave.
--
Dave Chinner
david@xxxxxxxxxxxxx
