[PATCH v1 03/14] mm: add noio support in filemap_get_pages

Stefan Roesch
2022-02-14T17:44:33Z

This adds noio support for async buffered writes in filemap_get_pages.
The idea is to handle the failure gracefully and return -EAGAIN if we
can't get the memory quickly.

Signed-off-by: Stefan Roesch <shr@fb.com>
---
mm/filemap.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/mm/filemap.c b/mm/filemap.c
index d2fb817c0845..0ff4278c3961 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -2591,10 +2591,15 @@ static int filemap_get_pages(struct kiocb *iocb, struct iov_iter *iter,
filemap_get_read_batch(mapping, index, last_index, fbatch);
}
if (!folio_batch_count(fbatch)) {
+ unsigned int pflags;
+
if (iocb->ki_flags & (IOCB_NOWAIT | IOCB_WAITQ))
- return -EAGAIN;
+ pflags = memalloc_noio_save();
err = filemap_create_folio(filp, mapping,
iocb->ki_pos >> PAGE_SHIFT, fbatch);
+ if (iocb->ki_flags & (IOCB_NOWAIT | IOCB_WAITQ))
+ memalloc_noio_restore(pflags);
+
if (err == AOP_TRUNCATED_PAGE)
goto retry;
return err;
--
2.30.2