mm: implement ->map_pages for page cache

[linux.git] / mm / filemap.c

diff --git a/mm/filemap.c b/mm/filemap.c
index 21781f1fe52b676e2b1f7dba5b2477f898503b1f..3f9b5fbb623fae2adef7d74adae65775b1a99666 100644 (file)
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -33,6 +33,7 @@
 #include <linux/hardirq.h> /* for BUG_ON(!in_atomic()) only */
 #include <linux/memcontrol.h>
 #include <linux/cleancache.h>
+#include <linux/rmap.h>
 #include "internal.h"
 
 #define CREATE_TRACE_POINTS
@@ -2064,6 +2065,78 @@ page_not_uptodate:
 }
 EXPORT_SYMBOL(filemap_fault);
 
+void filemap_map_pages(struct vm_area_struct *vma, struct vm_fault *vmf)
+{
+       struct radix_tree_iter iter;
+       void **slot;
+       struct file *file = vma->vm_file;
+       struct address_space *mapping = file->f_mapping;
+       loff_t size;
+       struct page *page;
+       unsigned long address = (unsigned long) vmf->virtual_address;
+       unsigned long addr;
+       pte_t *pte;
+
+       rcu_read_lock();
+       radix_tree_for_each_slot(slot, &mapping->page_tree, &iter, vmf->pgoff) {
+               if (iter.index > vmf->max_pgoff)
+                       break;
+repeat:
+               page = radix_tree_deref_slot(slot);
+               if (unlikely(!page))
+                       goto next;
+               if (radix_tree_exception(page)) {
+                       if (radix_tree_deref_retry(page))
+                               break;
+                       else
+                               goto next;
+               }
+
+               if (!page_cache_get_speculative(page))
+                       goto repeat;
+
+               /* Has the page moved? */
+               if (unlikely(page != *slot)) {
+                       page_cache_release(page);
+                       goto repeat;
+               }
+
+               if (!PageUptodate(page) ||
+                               PageReadahead(page) ||
+                               PageHWPoison(page))
+                       goto skip;
+               if (!trylock_page(page))
+                       goto skip;
+
+               if (page->mapping != mapping || !PageUptodate(page))
+                       goto unlock;
+
+               size = i_size_read(mapping->host) + PAGE_CACHE_SIZE - 1;
+               if (page->index >= size >> PAGE_CACHE_SHIFT)
+                       goto unlock;
+
+               pte = vmf->pte + page->index - vmf->pgoff;
+               if (!pte_none(*pte))
+                       goto unlock;
+
+               if (file->f_ra.mmap_miss > 0)
+                       file->f_ra.mmap_miss--;
+               addr = address + (page->index - vmf->pgoff) * PAGE_SIZE;
+               do_set_pte(vma, addr, page, pte, false, false);
+               unlock_page(page);
+               goto next;
+unlock:
+               unlock_page(page);
+skip:
+               page_cache_release(page);
+next:
+               if (iter.index == vmf->max_pgoff)
+                       break;
+       }
+       rcu_read_unlock();
+}
+EXPORT_SYMBOL(filemap_map_pages);
+
 int filemap_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf)
 {
        struct page *page = vmf->page;
@@ -2093,6 +2166,7 @@ EXPORT_SYMBOL(filemap_page_mkwrite);
 
 const struct vm_operations_struct generic_file_vm_ops = {
        .fault          = filemap_fault,
+       .map_pages      = filemap_map_pages,
        .page_mkwrite   = filemap_page_mkwrite,
        .remap_pages    = generic_file_remap_pages,
 };