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-rw-r--r--mm/gup.c105
1 files changed, 105 insertions, 0 deletions
diff --git a/mm/gup.c b/mm/gup.c
index 8e0a0a3a2b2d..2c08248d4fa2 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -28,6 +28,111 @@ struct follow_page_context {
unsigned int page_mask;
};
+typedef int (*set_dirty_func_t)(struct page *page);
+
+static void __put_user_pages_dirty(struct page **pages,
+ unsigned long npages,
+ set_dirty_func_t sdf)
+{
+ unsigned long index;
+
+ for (index = 0; index < npages; index++) {
+ struct page *page = compound_head(pages[index]);
+
+ /*
+ * Checking PageDirty at this point may race with
+ * clear_page_dirty_for_io(), but that's OK. Two key cases:
+ *
+ * 1) This code sees the page as already dirty, so it skips
+ * the call to sdf(). That could happen because
+ * clear_page_dirty_for_io() called page_mkclean(),
+ * followed by set_page_dirty(). However, now the page is
+ * going to get written back, which meets the original
+ * intention of setting it dirty, so all is well:
+ * clear_page_dirty_for_io() goes on to call
+ * TestClearPageDirty(), and write the page back.
+ *
+ * 2) This code sees the page as clean, so it calls sdf().
+ * The page stays dirty, despite being written back, so it
+ * gets written back again in the next writeback cycle.
+ * This is harmless.
+ */
+ if (!PageDirty(page))
+ sdf(page);
+
+ put_user_page(page);
+ }
+}
+
+/**
+ * put_user_pages_dirty() - release and dirty an array of gup-pinned pages
+ * @pages: array of pages to be marked dirty and released.
+ * @npages: number of pages in the @pages array.
+ *
+ * "gup-pinned page" refers to a page that has had one of the get_user_pages()
+ * variants called on that page.
+ *
+ * For each page in the @pages array, make that page (or its head page, if a
+ * compound page) dirty, if it was previously listed as clean. Then, release
+ * the page using put_user_page().
+ *
+ * Please see the put_user_page() documentation for details.
+ *
+ * set_page_dirty(), which does not lock the page, is used here.
+ * Therefore, it is the caller's responsibility to ensure that this is
+ * safe. If not, then put_user_pages_dirty_lock() should be called instead.
+ *
+ */
+void put_user_pages_dirty(struct page **pages, unsigned long npages)
+{
+ __put_user_pages_dirty(pages, npages, set_page_dirty);
+}
+EXPORT_SYMBOL(put_user_pages_dirty);
+
+/**
+ * put_user_pages_dirty_lock() - release and dirty an array of gup-pinned pages
+ * @pages: array of pages to be marked dirty and released.
+ * @npages: number of pages in the @pages array.
+ *
+ * For each page in the @pages array, make that page (or its head page, if a
+ * compound page) dirty, if it was previously listed as clean. Then, release
+ * the page using put_user_page().
+ *
+ * Please see the put_user_page() documentation for details.
+ *
+ * This is just like put_user_pages_dirty(), except that it invokes
+ * set_page_dirty_lock(), instead of set_page_dirty().
+ *
+ */
+void put_user_pages_dirty_lock(struct page **pages, unsigned long npages)
+{
+ __put_user_pages_dirty(pages, npages, set_page_dirty_lock);
+}
+EXPORT_SYMBOL(put_user_pages_dirty_lock);
+
+/**
+ * put_user_pages() - release an array of gup-pinned pages.
+ * @pages: array of pages to be marked dirty and released.
+ * @npages: number of pages in the @pages array.
+ *
+ * For each page in the @pages array, release the page using put_user_page().
+ *
+ * Please see the put_user_page() documentation for details.
+ */
+void put_user_pages(struct page **pages, unsigned long npages)
+{
+ unsigned long index;
+
+ /*
+ * TODO: this can be optimized for huge pages: if a series of pages is
+ * physically contiguous and part of the same compound page, then a
+ * single operation to the head page should suffice.
+ */
+ for (index = 0; index < npages; index++)
+ put_user_page(pages[index]);
+}
+EXPORT_SYMBOL(put_user_pages);
+
static struct page *no_page_table(struct vm_area_struct *vma,
unsigned int flags)
{