Patch "nbd: ratelimit error msgs after socket close" has been added to the 4.4-stable tree

Patch "nbd: ratelimit error msgs after socket close" has been added to the 4.4-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

    nbd: ratelimit error msgs after socket close

to the 4.4-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     nbd-ratelimit-error-msgs-after-socket-close.patch
and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From da6ccaaa79caca4f38b540b651238f87215217a2 Mon Sep 17 00:00:00 2001
From: Dan Streetman <dan.streetman@canonical.com>
Date: Thu, 14 Jan 2016 13:42:32 -0500
Subject: nbd: ratelimit error msgs after socket close

From: Dan Streetman <dan.streetman@canonical.com>

commit da6ccaaa79caca4f38b540b651238f87215217a2 upstream.

Make the "Attempted send on closed socket" error messages generated in
nbd_request_handler() ratelimited.

When the nbd socket is shutdown, the nbd_request_handler() function emits
an error message for every request remaining in its queue.  If the queue
is large, this will spam a large amount of messages to the log.  There's
no need for a separate error message for each request, so this patch
ratelimits it.

In the specific case this was found, the system was virtual and the error
messages were logged to the serial port, which overwhelmed it.

Fixes: 4d48a542b427 ("nbd: fix I/O hang on disconnected nbds")
Signed-off-by: Dan Streetman <dan.streetman@canonical.com>
Signed-off-by: Markus Pargmann <mpa@pengutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/block/nbd.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/drivers/block/nbd.c
+++ b/drivers/block/nbd.c
@@ -618,8 +618,8 @@ static void nbd_request_handler(struct r
 			req, req->cmd_type);
 
 		if (unlikely(!nbd->sock)) {
-			dev_err(disk_to_dev(nbd->disk),
-				"Attempted send on closed socket\n");
+			dev_err_ratelimited(disk_to_dev(nbd->disk),
+					    "Attempted send on closed socket\n");
 			req->errors++;
 			nbd_end_request(nbd, req);
 			spin_lock_irq(q->queue_lock);


Patches currently in stable-queue which might be from dan.streetman@canonical.com are

queue-4.4/nbd-ratelimit-error-msgs-after-socket-close.patch