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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: Matthew Wilcox (Oracle) <willy@infradead.org>
This commit is contained in:
Matthew Wilcox (Oracle) 2021-07-24 23:37:13 -04:00
parent 56a4d67c26
commit 4687fdbb80
1 changed files with 18 additions and 0 deletions
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18
mm/filemap.c
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@ -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;