Commit 4687fdbb authored by Matthew Wilcox (Oracle)'s avatar Matthew Wilcox (Oracle)
Browse files

mm/filemap: Support VM_HUGEPAGE for file mappings 



If the VM_HUGEPAGE flag is set, attempt to allocate PMD-sized folios
during readahead, even if we have no history of readahead being
successful.

Signed-off-by: default avatarMatthew Wilcox (Oracle) <willy@infradead.org>
parent 56a4d67c

mm/filemap.c

+18 −0
Original line number Diff line number Diff line
@@ -2995,6 +2995,24 @@ static struct file *do_sync_mmap_readahead(struct vm_fault *vmf) 
	struct file *fpin = NULL;

	unsigned int mmap_miss;



#ifdef CONFIG_TRANSPARENT_HUGEPAGE

	/* Use the readahead code, even if readahead is disabled */

	if (vmf->vma->vm_flags & VM_HUGEPAGE) {

		fpin = maybe_unlock_mmap_for_io(vmf, fpin);

		ractl._index &= ~((unsigned long)HPAGE_PMD_NR - 1);

		ra->size = HPAGE_PMD_NR;

		/*

		 * Fetch two PMD folios, so we get the chance to actually

		 * readahead, unless we've been told not to.

		 */

		if (!(vmf->vma->vm_flags & VM_RAND_READ))

			ra->size *= 2;

		ra->async_size = HPAGE_PMD_NR;

		page_cache_ra_order(&ractl, ra, HPAGE_PMD_ORDER);

		return fpin;

	}

#endif



	/* If we don't want any read-ahead, don't bother */

	if (vmf->vma->vm_flags & VM_RAND_READ)

		return fpin;