[PATCHv3 16/41] filemap: allocate huge page in pagecache_get_page(), if allowed

Kirill A. Shutemov
2016-09-15T11:54:58Z

Write path allocate pages using pagecache_get_page(). We should be able
to allocate huge pages there, if it's allowed. As usually, fallback to
small pages, if failed.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
---
mm/filemap.c | 18 ++++++++++++++++--
1 file changed, 16 insertions(+), 2 deletions(-)

diff --git a/mm/filemap.c b/mm/filemap.c
index b77bcf6843ee..05b42d3e5ed8 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -1310,13 +1310,16 @@ repeat:

no_page:
if (!page && (fgp_flags & FGP_CREAT)) {
+ pgoff_t hoffset;
int err;
if ((fgp_flags & FGP_WRITE) && mapping_cap_account_dirty(mapping))
gfp_mask |= __GFP_WRITE;
if (fgp_flags & FGP_NOFS)
gfp_mask &= ~__GFP_FS;

- page = __page_cache_alloc(gfp_mask);
+ page = page_cache_alloc_huge(mapping, offset, gfp_mask);
+no_huge: if (!page)
+ page = __page_cache_alloc(gfp_mask);
if (!page)
return NULL;

@@ -1327,14 +1330,25 @@ no_page:
if (fgp_flags & FGP_ACCESSED)
__SetPageReferenced(page);

- err = add_to_page_cache_lru(page, mapping, offset,
+ if (PageTransHuge(page))
+ hoffset = round_down(offset, HPAGE_PMD_NR);
+ else
+ hoffset = offset;
+
+ err = add_to_page_cache_lru(page, mapping, hoffset,
gfp_mask & GFP_RECLAIM_MASK);
if (unlikely(err)) {
+ if (PageTransHuge(page)) {
+ put_page(page);
+ page = NULL;
+ goto no_huge;
+ }
put_page(page);
page = NULL;
if (err == -EEXIST)
goto repeat;
}
+ page += offset - hoffset;
}

return page;