[PATCH v2 32/34] goldfish_pipe: convert put_page() to put_user_page*()

john.hubbard
2019-08-04T22:50:53Z

Note that this effectively changes the code's behavior in
qp_release_pages(): it now ultimately calls set_page_dirty_lock(),
instead of set_page_dirty(). This is probably more accurate.

As Christoph Hellwig put it, "set_page_dirty() is only safe if we are
dealing with a file backed page where we have reference on the inode it
hangs off." [1]

[1] https://lore.kernel.org/r/20190723153640.GB720@lst.de

Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Roman Kiryanov <rkir@google.com>
Signed-off-by: John Hubbard <jhubbard@nvidia.com>
---
drivers/platform/goldfish/goldfish_pipe.c | 9 +++------
1 file changed, 3 insertions(+), 6 deletions(-)

diff --git a/drivers/platform/goldfish/goldfish_pipe.c b/drivers/platform/goldfish/goldfish_pipe.c
index cef0133aa47a..2bd21020e288 100644
--- a/drivers/platform/goldfish/goldfish_pipe.c
+++ b/drivers/platform/goldfish/goldfish_pipe.c
@@ -288,15 +288,12 @@ static int pin_user_pages(unsigned long first_page,
static void release_user_pages(struct page **pages, int pages_count,
int is_write, s32 consumed_size)
{
- int i;
+ bool dirty = !is_write && consumed_size > 0;

- for (i = 0; i < pages_count; i++) {
- if (!is_write && consumed_size > 0)
- set_page_dirty(pages[i]);
- put_page(pages[i]);
- }
+ put_user_pages_dirty_lock(pages, pages_count, dirty);
}

+
/* Populate the call parameters, merging adjacent pages together */
static void populate_rw_params(struct page **pages,
int pages_count,
--
2.22.0