Commit 8808ecab authored by Matthew Wilcox (Oracle)'s avatar Matthew Wilcox (Oracle) Committed by Andrew Morton
Browse files

filemap: convert filemap_map_pmd() to take a folio 

Patch series "Some more filemap folio conversions".

Three more places which could easily be converted to folios.  The third
one fixes a minor bug in readahead_expand(), but it's only a performance
bug and there are few users of readahead_expand(), so I don't think it's
worth backporting.


This patch (of 3):

Save a few calls to compound_head().  We specify exactly which page from
the folio to use by passing in start_pgoff, which means this will work for
a folio which is larger than PMD size.  The rest of the VM isn't prepared
for that yet, but now this function is.

Link: https://lkml.kernel.org/r/20230116193941.2148487-1-willy@infradead.org
Link: https://lkml.kernel.org/r/20230116193941.2148487-2-willy@infradead.org


Signed-off-by: default avatarMatthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: default avatarWilliam Kucharski <william.kucharski@oracle.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 5b4bd90f

mm/filemap.c

+10 −8
Original line number Diff line number Diff line
@@ -3259,22 +3259,24 @@ vm_fault_t filemap_fault(struct vm_fault *vmf) 
}

EXPORT_SYMBOL(filemap_fault);



static bool filemap_map_pmd(struct vm_fault *vmf, struct page *page)

static bool filemap_map_pmd(struct vm_fault *vmf, struct folio *folio,

		pgoff_t start)

{

	struct mm_struct *mm = vmf->vma->vm_mm;



	/* Huge page is mapped? No need to proceed. */

	if (pmd_trans_huge(*vmf->pmd)) {

		unlock_page(page);

		put_page(page);

		folio_unlock(folio);

		folio_put(folio);

		return true;

	}



	if (pmd_none(*vmf->pmd) && PageTransHuge(page)) {

	if (pmd_none(*vmf->pmd) && folio_test_pmd_mappable(folio)) {

		struct page *page = folio_file_page(folio, start);

		vm_fault_t ret = do_set_pmd(vmf, page);

		if (!ret) {

			/* The page is mapped successfully, reference consumed. */

			unlock_page(page);

			folio_unlock(folio);

			return true;

		}

	}
@@ -3284,8 +3286,8 @@ static bool filemap_map_pmd(struct vm_fault *vmf, struct page *page) 


	/* See comment in handle_pte_fault() */

	if (pmd_devmap_trans_unstable(vmf->pmd)) {

		unlock_page(page);

		put_page(page);

		folio_unlock(folio);

		folio_put(folio);

		return true;

	}
@@ -3368,7 +3370,7 @@ vm_fault_t filemap_map_pages(struct vm_fault *vmf, 
	if (!folio)

		goto out;



	if (filemap_map_pmd(vmf, &folio->page)) {

	if (filemap_map_pmd(vmf, folio, start_pgoff)) {

		ret = VM_FAULT_NOPAGE;

		goto out;

	}