Commit 7a7256d5 authored by Matthew Wilcox (Oracle)'s avatar Matthew Wilcox (Oracle) Committed by Andrew Morton
Browse files

shmem: convert shmem_mfill_atomic_pte() to use a folio 

Assert that this is a single-page folio as there are several assumptions
in here that it's exactly PAGE_SIZE bytes large.  Saves several calls to
compound_head() and removes the last caller of shmem_alloc_page().

Link: https://lkml.kernel.org/r/20220902194653.1739778-18-willy@infradead.org


Signed-off-by: default avatarMatthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 65995918

mm/shmem.c

+19 −26
Original line number Diff line number Diff line
@@ -2374,12 +2374,6 @@ static struct inode *shmem_get_inode(struct super_block *sb, struct inode *dir, 
}



#ifdef CONFIG_USERFAULTFD

static struct page *shmem_alloc_page(gfp_t gfp,

			struct shmem_inode_info *info, pgoff_t index)

{

	return &shmem_alloc_folio(gfp, info, index)->page;

}



int shmem_mfill_atomic_pte(struct mm_struct *dst_mm,

			   pmd_t *dst_pmd,

			   struct vm_area_struct *dst_vma,
@@ -2395,7 +2389,6 @@ int shmem_mfill_atomic_pte(struct mm_struct *dst_mm, 
	pgoff_t pgoff = linear_page_index(dst_vma, dst_addr);

	void *page_kaddr;

	struct folio *folio;

	struct page *page;

	int ret;

	pgoff_t max_off;
@@ -2414,53 +2407,53 @@ int shmem_mfill_atomic_pte(struct mm_struct *dst_mm, 


	if (!*pagep) {

		ret = -ENOMEM;

		page = shmem_alloc_page(gfp, info, pgoff);

		if (!page)

		folio = shmem_alloc_folio(gfp, info, pgoff);

		if (!folio)

			goto out_unacct_blocks;



		if (!zeropage) {	/* COPY */

			page_kaddr = kmap_atomic(page);

			page_kaddr = kmap_local_folio(folio, 0);

			ret = copy_from_user(page_kaddr,

					     (const void __user *)src_addr,

					     PAGE_SIZE);

			kunmap_atomic(page_kaddr);

			kunmap_local(page_kaddr);



			/* fallback to copy_from_user outside mmap_lock */

			if (unlikely(ret)) {

				*pagep = page;

				*pagep = &folio->page;

				ret = -ENOENT;

				/* don't free the page */

				goto out_unacct_blocks;

			}



			flush_dcache_page(page);

			flush_dcache_folio(folio);

		} else {		/* ZEROPAGE */

			clear_user_highpage(page, dst_addr);

			clear_user_highpage(&folio->page, dst_addr);

		}

	} else {

		page = *pagep;

		folio = page_folio(*pagep);

		VM_BUG_ON_FOLIO(folio_test_large(folio), folio);

		*pagep = NULL;

	}



	VM_BUG_ON(PageLocked(page));

	VM_BUG_ON(PageSwapBacked(page));

	__SetPageLocked(page);

	__SetPageSwapBacked(page);

	__SetPageUptodate(page);

	VM_BUG_ON(folio_test_locked(folio));

	VM_BUG_ON(folio_test_swapbacked(folio));

	__folio_set_locked(folio);

	__folio_set_swapbacked(folio);

	__folio_mark_uptodate(folio);



	ret = -EFAULT;

	max_off = DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE);

	if (unlikely(pgoff >= max_off))

		goto out_release;



	folio = page_folio(page);

	ret = shmem_add_to_page_cache(folio, mapping, pgoff, NULL,

				      gfp & GFP_RECLAIM_MASK, dst_mm);

	if (ret)

		goto out_release;



	ret = mfill_atomic_install_pte(dst_mm, dst_pmd, dst_vma, dst_addr,

				       page, true, wp_copy);

				       &folio->page, true, wp_copy);

	if (ret)

		goto out_delete_from_cache;
@@ -2470,13 +2463,13 @@ int shmem_mfill_atomic_pte(struct mm_struct *dst_mm, 
	shmem_recalc_inode(inode);

	spin_unlock_irq(&info->lock);



	unlock_page(page);

	folio_unlock(folio);

	return 0;

out_delete_from_cache:

	delete_from_page_cache(page);

	filemap_remove_folio(folio);

out_release:

	unlock_page(page);

	put_page(page);

	folio_unlock(folio);

	folio_put(folio);

out_unacct_blocks:

	shmem_inode_unacct_blocks(inode, 1);

	return ret;