*/
/*
- * Remove a page from the page cache and free it. Caller has to make
+ * Delete a page from the page cache and free it. Caller has to make
* sure the page is locked and that nobody else uses it - or that usage
* is safe. The caller must hold the mapping's tree_lock.
*/
-void __remove_from_page_cache(struct page *page)
+void __delete_from_page_cache(struct page *page)
{
struct address_space *mapping = page->mapping;
}
}
-void remove_from_page_cache(struct page *page)
+/**
+ * delete_from_page_cache - delete page from page cache
+ * @page: the page which the kernel is trying to remove from page cache
+ *
+ * This must be called only on pages that have been verified to be in the page
+ * cache and locked. It will never put the page into the free list, the caller
+ * has a reference on the page.
+ */
+void delete_from_page_cache(struct page *page)
{
struct address_space *mapping = page->mapping;
void (*freepage)(struct page *);
freepage = mapping->a_ops->freepage;
spin_lock_irq(&mapping->tree_lock);
- __remove_from_page_cache(page);
+ __delete_from_page_cache(page);
spin_unlock_irq(&mapping->tree_lock);
mem_cgroup_uncharge_cache_page(page);
if (freepage)
freepage(page);
+ page_cache_release(page);
}
-EXPORT_SYMBOL(remove_from_page_cache);
+EXPORT_SYMBOL(delete_from_page_cache);
static int sleep_on_page(void *word)
{
}
EXPORT_SYMBOL(filemap_write_and_wait_range);
+/**
+ * replace_page_cache_page - replace a pagecache page with a new one
+ * @old: page to be replaced
+ * @new: page to replace with
+ * @gfp_mask: allocation mode
+ *
+ * This function replaces a page in the pagecache with a new one. On
+ * success it acquires the pagecache reference for the new page and
+ * drops it for the old page. Both the old and new pages must be
+ * locked. This function does not add the new page to the LRU, the
+ * caller must do that.
+ *
+ * The remove + add is atomic. The only way this function can fail is
+ * memory allocation failure.
+ */
+int replace_page_cache_page(struct page *old, struct page *new, gfp_t gfp_mask)
+{
+ int error;
+ struct mem_cgroup *memcg = NULL;
+
+ VM_BUG_ON(!PageLocked(old));
+ VM_BUG_ON(!PageLocked(new));
+ VM_BUG_ON(new->mapping);
+
+ /*
+ * This is not page migration, but prepare_migration and
+ * end_migration does enough work for charge replacement.
+ *
+ * In the longer term we probably want a specialized function
+ * for moving the charge from old to new in a more efficient
+ * manner.
+ */
+ error = mem_cgroup_prepare_migration(old, new, &memcg, gfp_mask);
+ if (error)
+ return error;
+
+ error = radix_tree_preload(gfp_mask & ~__GFP_HIGHMEM);
+ if (!error) {
+ struct address_space *mapping = old->mapping;
+ void (*freepage)(struct page *);
+
+ pgoff_t offset = old->index;
+ freepage = mapping->a_ops->freepage;
+
+ page_cache_get(new);
+ new->mapping = mapping;
+ new->index = offset;
+
+ spin_lock_irq(&mapping->tree_lock);
+ __delete_from_page_cache(old);
+ error = radix_tree_insert(&mapping->page_tree, offset, new);
+ BUG_ON(error);
+ mapping->nrpages++;
+ __inc_zone_page_state(new, NR_FILE_PAGES);
+ if (PageSwapBacked(new))
+ __inc_zone_page_state(new, NR_SHMEM);
+ spin_unlock_irq(&mapping->tree_lock);
+ radix_tree_preload_end();
+ if (freepage)
+ freepage(old);
+ page_cache_release(old);
+ mem_cgroup_end_migration(memcg, old, new, true);
+ } else {
+ mem_cgroup_end_migration(memcg, old, new, false);
+ }
+
+ return error;
+}
+EXPORT_SYMBOL_GPL(replace_page_cache_page);
+
/**
* add_to_page_cache_locked - add a locked page to the pagecache
* @page: page to add
__lock_page(page);
return 1;
} else {
- up_read(&mm->mmap_sem);
- wait_on_page_locked(page);
+ if (!(flags & FAULT_FLAG_RETRY_NOWAIT)) {
+ up_read(&mm->mmap_sem);
+ wait_on_page_locked(page);
+ }
return 0;
}
}
page = radix_tree_deref_slot((void **)pages[i]);
if (unlikely(!page))
continue;
+
+ /*
+ * This can only trigger when the entry at index 0 moves out
+ * of or back to the root: none yet gotten, safe to restart.
+ */
if (radix_tree_deref_retry(page)) {
- if (ret)
- start = pages[ret-1]->index;
+ WARN_ON(start | i);
goto restart;
}
pages[ret] = page;
ret++;
}
+
+ /*
+ * If all entries were removed before we could secure them,
+ * try again, because callers stop trying once 0 is returned.
+ */
+ if (unlikely(!ret && nr_found))
+ goto restart;
rcu_read_unlock();
return ret;
}
page = radix_tree_deref_slot((void **)pages[i]);
if (unlikely(!page))
continue;
+
+ /*
+ * This can only trigger when the entry at index 0 moves out
+ * of or back to the root: none yet gotten, safe to restart.
+ */
if (radix_tree_deref_retry(page))
goto restart;
page = radix_tree_deref_slot((void **)pages[i]);
if (unlikely(!page))
continue;
+
+ /*
+ * This can only trigger when the entry at index 0 moves out
+ * of or back to the root: none yet gotten, safe to restart.
+ */
if (radix_tree_deref_retry(page))
goto restart;
pages[ret] = page;
ret++;
}
+
+ /*
+ * If all entries were removed before we could secure them,
+ * try again, because callers stop trying once 0 is returned.
+ */
+ if (unlikely(!ret && nr_found))
+ goto restart;
rcu_read_unlock();
if (ret)
git.openpandora.org / pandora-kernel.git / blobdiff