Re: [PATCH] xfs: Use kmem_zalloc for bp->b_pages.

Sean Fu
2019-03-10T05:07:45Z

On Sat, Mar 09, 2019 at 09:32:30AM -0800, Darrick J. Wong wrote:
> On Sat, Mar 09, 2019 at 11:36:36PM +0800, Sean Fu wrote:
> > Change the allocation of bp->b_pages to use kmem_zalloc instead of
> > kmem_alloc.
> > Remove unnecessary memset for bp->b_pages.
> >
> > This reduces text size by 42 bytes.
> > Before:
> > text data bss dec hex filename
> > 23335 588 8 23931 5d7b ./fs/xfs/xfs_buf.o
> > After:
> > text data bss dec hex filename
> > 23293 588 8 23889 5d51 ./fs/xfs/xfs_buf.o
> >
> > Signed-off-by: Sean Fu <fxinrong@gmail.com>
> > ---
> > fs/xfs/xfs_buf.c | 3 +--
> > 1 file changed, 1 insertion(+), 2 deletions(-)
> >
> > diff --git a/fs/xfs/xfs_buf.c b/fs/xfs/xfs_buf.c
> > index 4f5f2ff3f70f..be4f740b97c1 100644
> > --- a/fs/xfs/xfs_buf.c
> > +++ b/fs/xfs/xfs_buf.c
> > @@ -289,12 +289,11 @@ _xfs_buf_get_pages(
> > if (page_count <= XB_PAGES) {
> > bp->b_pages = bp->b_page_array;
> > } else {
> > - bp->b_pages = kmem_alloc(sizeof(struct page *) *
> > + bp->b_pages = kmem_zalloc(sizeof(struct page *) *
> > page_count, KM_NOFS);
> > if (bp->b_pages == NULL)
> > return -ENOMEM;
> > }
> > - memset(bp->b_pages, 0, sizeof(struct page *) * page_count);
>
> Does this leave b_pages uninitialized in the page_count <= XB_PAGES
> case?
bp is allocated by kmem_zone_zalloc, But i will take a deep look at xfs_buf_associate_memory.
>
> --D
>
> > }
> > return 0;
> > }
> > --
> > 2.16.4
> >