From: "Kirill A. Shutemov" <kirill.shutemov@xxxxxxxxxxxxxxx>
It provide enough functionality for simple cases like ramfs. Need to be
extended later.
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
---
mm/filemap.c | 75 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 75 insertions(+)
diff --git a/mm/filemap.c b/mm/filemap.c
index 57611be..032fec39 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -1781,6 +1781,80 @@ page_not_uptodate:
}
EXPORT_SYMBOL(filemap_fault);
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+static int filemap_huge_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
+{
+ struct file *file = vma->vm_file;
+ struct address_space *mapping = file->f_mapping;
+ struct inode *inode = mapping->host;
+ pgoff_t size, offset = vmf->pgoff;
+ unsigned long address = (unsigned long) vmf->virtual_address;
+ struct page *page;
+ int ret = 0;
+
+ BUG_ON(((address >> PAGE_SHIFT) & HPAGE_CACHE_INDEX_MASK) !=
+ (offset & HPAGE_CACHE_INDEX_MASK));
+
+retry:
+ page = find_get_page(mapping, offset);
+ if (!page) {
+ gfp_t gfp_mask = mapping_gfp_mask(mapping) | __GFP_COLD;
+ page = alloc_pages(gfp_mask, HPAGE_PMD_ORDER);
+ if (!page) {
+ count_vm_event(THP_FAULT_FALLBACK);
+ return VM_FAULT_OOM;
+ }
+ count_vm_event(THP_FAULT_ALLOC);
+ ret = add_to_page_cache_lru(page, mapping, offset, GFP_KERNEL);
+ if (ret == 0)
+ ret = mapping->a_ops->readpage(file, page);
+ else if (ret == -EEXIST)
+ ret = 0; /* losing race to add is OK */
+ page_cache_release(page);
+ if (!ret || ret == AOP_TRUNCATED_PAGE)
+ goto retry;
+ return ret;
+ }
+
+ if (!lock_page_or_retry(page, vma->vm_mm, vmf->flags)) {
+ page_cache_release(page);
+ return ret | VM_FAULT_RETRY;
+ }
+
+ /* Did it get truncated? */
+ if (unlikely(page->mapping != mapping)) {
+ unlock_page(page);
+ put_page(page);
+ goto retry;
+ }
+ VM_BUG_ON(page->index != offset);
+ VM_BUG_ON(!PageUptodate(page));
+
+ if (!PageTransHuge(page)) {
+ unlock_page(page);
+ put_page(page);
+ /* Ask fallback to small pages */
+ return VM_FAULT_OOM;
+ }
+
+ /*
+ * Found the page and have a reference on it.
+ * We must recheck i_size under page lock.
+ */
+ size = (i_size_read(inode) + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
+ if (unlikely(offset >= size)) {
+ unlock_page(page);
+ page_cache_release(page);
+ return VM_FAULT_SIGBUS;
+ }
+
+ vmf->page = page;
+ return ret | VM_FAULT_LOCKED;
+}
+#else
+#define filemap_huge_fault NULL
+#endif
+
int filemap_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf)
{
struct page *page = vmf->page;
@@ -1810,6 +1884,7 @@ EXPORT_SYMBOL(filemap_page_mkwrite);
const struct vm_operations_struct generic_file_vm_ops = {
.fault = filemap_fault,
+ .huge_fault = filemap_huge_fault,
.page_mkwrite = filemap_page_mkwrite,
.remap_pages = generic_file_remap_pages,
};
--
1.7.10.4
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