nvme-tcp: check page by sendpage_ok() before calling kernel_sendpage()

Currently nvme_tcp_try_send_data() doesn't use kernel_sendpage() to
send slab pages. But for pages allocated by __get_free_pages() without
__GFP_COMP, which also have refcount as 0, they are still sent by
kernel_sendpage() to remote end, this is problematic.

The new introduced helper sendpage_ok() checks both PageSlab tag and
page_count counter, and returns true if the checking page is OK to be
sent by kernel_sendpage().

This patch fixes the page checking issue of nvme_tcp_try_send_data()
with sendpage_ok(). If sendpage_ok() returns true, send this page by
kernel_sendpage(), otherwise use sock_no_sendpage to handle this page.

Signed-off-by: Coly Li <colyli@suse.de>
Cc: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Hannes Reinecke <hare@suse.de>
Cc: Jan Kara <jack@suse.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Mikhail Skorzhinskii <mskorzhinskiy@solarflare.com>
Cc: Philipp Reisner <philipp.reisner@linbit.com>
Cc: Sagi Grimberg <sagi@grimberg.me>
Cc: Vlastimil Babka <vbabka@suse.com>
Cc: stable@vger.kernel.org
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/nvme/host/tcp.c b/drivers/nvme/host/tcp.c
index 8f4f29f..d6a3e14 100644 (file)
--- a/drivers/nvme/host/tcp.c
+++ b/drivers/nvme/host/tcp.c
@@ -913,12 +913,11 @@ static int nvme_tcp_try_send_data(struct nvme_tcp_request *req)
                else
                        flags |= MSG_MORE | MSG_SENDPAGE_NOTLAST;
 
-               /* can't zcopy slab pages */
-               if (unlikely(PageSlab(page))) {
-                       ret = sock_no_sendpage(queue->sock, page, offset, len,
+               if (sendpage_ok(page)) {
+                       ret = kernel_sendpage(queue->sock, page, offset, len,
                                        flags);
                } else {
-                       ret = kernel_sendpage(queue->sock, page, offset, len,
+                       ret = sock_no_sendpage(queue->sock, page, offset, len,
                                        flags);
                }
                if (ret <= 0)