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filemap: convert filemap_map_pmd() to take a folio

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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: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: William Kucharski <william.kucharski@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Matthew Wilcox (Oracle) 2023-01-16 19:39:39 +00:00 committed by Andrew Morton
parent 5b4bd90f9a
commit 8808ecab3a
1 changed files with 10 additions and 8 deletions
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18
mm/filemap.c
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@ -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;
}