mm: add find_get_entries_tag()

[linux-drm-fsl-dcu.git] / mm / filemap.c

diff --git a/mm/filemap.c b/mm/filemap.c
index 847ee43c28068a0fb744fe124c1d8afa429d0719..1e215fc36c835eb6c8d79bc16b160aca0e44fd07 100644 (file)
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -11,6 +11,7 @@
  */
 #include <linux/export.h>
 #include <linux/compiler.h>
+#include <linux/dax.h>
 #include <linux/fs.h>
 #include <linux/uaccess.h>
 #include <linux/capability.h>
@@ -123,9 +124,9 @@ static void page_cache_tree_delete(struct address_space *mapping,
        __radix_tree_lookup(&mapping->page_tree, page->index, &node, &slot);
 
        if (shadow) {
-               mapping->nrshadows++;
+               mapping->nrexceptional++;
                /*
-                * Make sure the nrshadows update is committed before
+                * Make sure the nrexceptional update is committed before
                 * the nrpages update so that final truncate racing
                 * with reclaim does not see both counters 0 at the
                 * same time and miss a shadow entry.
@@ -579,9 +580,13 @@ static int page_cache_tree_insert(struct address_space *mapping,
                p = radix_tree_deref_slot_protected(slot, &mapping->tree_lock);
                if (!radix_tree_exceptional_entry(p))
                        return -EEXIST;
+
+               if (WARN_ON(dax_mapping(mapping)))
+                       return -EINVAL;
+
                if (shadowp)
                        *shadowp = p;
-               mapping->nrshadows--;
+               mapping->nrexceptional--;
                if (node)
                        workingset_node_shadows_dec(node);
        }
@@ -1245,9 +1250,9 @@ repeat:
                        if (radix_tree_deref_retry(page))
                                goto restart;
                        /*
-                        * A shadow entry of a recently evicted page,
-                        * or a swap entry from shmem/tmpfs.  Return
-                        * it without attempting to raise page count.
+                        * A shadow entry of a recently evicted page, a swap
+                        * entry from shmem/tmpfs or a DAX entry.  Return it
+                        * without attempting to raise page count.
                         */
                        goto export;
                }
@@ -1494,6 +1499,74 @@ repeat:
 }
 EXPORT_SYMBOL(find_get_pages_tag);
 
+/**
+ * find_get_entries_tag - find and return entries that match @tag
+ * @mapping:   the address_space to search
+ * @start:     the starting page cache index
+ * @tag:       the tag index
+ * @nr_entries:        the maximum number of entries
+ * @entries:   where the resulting entries are placed
+ * @indices:   the cache indices corresponding to the entries in @entries
+ *
+ * Like find_get_entries, except we only return entries which are tagged with
+ * @tag.
+ */
+unsigned find_get_entries_tag(struct address_space *mapping, pgoff_t start,
+                       int tag, unsigned int nr_entries,
+                       struct page **entries, pgoff_t *indices)
+{
+       void **slot;
+       unsigned int ret = 0;
+       struct radix_tree_iter iter;
+
+       if (!nr_entries)
+               return 0;
+
+       rcu_read_lock();
+restart:
+       radix_tree_for_each_tagged(slot, &mapping->page_tree,
+                                  &iter, start, tag) {
+               struct page *page;
+repeat:
+               page = radix_tree_deref_slot(slot);
+               if (unlikely(!page))
+                       continue;
+               if (radix_tree_exception(page)) {
+                       if (radix_tree_deref_retry(page)) {
+                               /*
+                                * Transient condition which can only trigger
+                                * when entry at index 0 moves out of or back
+                                * to root: none yet gotten, safe to restart.
+                                */
+                               goto restart;
+                       }
+
+                       /*
+                        * A shadow entry of a recently evicted page, a swap
+                        * entry from shmem/tmpfs or a DAX entry.  Return it
+                        * without attempting to raise page count.
+                        */
+                       goto export;
+               }
+               if (!page_cache_get_speculative(page))
+                       goto repeat;
+
+               /* Has the page moved? */
+               if (unlikely(page != *slot)) {
+                       page_cache_release(page);
+                       goto repeat;
+               }
+export:
+               indices[ret] = iter.index;
+               entries[ret] = page;
+               if (++ret == nr_entries)
+                       break;
+       }
+       rcu_read_unlock();
+       return ret;
+}
+EXPORT_SYMBOL(find_get_entries_tag);
+
 /*
  * CD/DVDs are error prone. When a medium error occurs, the driver may fail
  * a _large_ part of the i/o request. Imagine the worst scenario: