From mboxrd@z Thu Jan 1 00:00:00 1970 From: Suresh Jayaraman Subject: Re: [PATCH] cifs: WARN_ON_ONCE if kernel_sendmsg() returns -ENOSPC Date: Wed, 03 Oct 2012 21:13:25 +0530 Message-ID: <506C5D1D.7050702@suse.com> References: <506BE618.7050606@suse.com> <20121003060410.07c30803@tlielax.poochiereds.net> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: Steve French , linux-cifs To: Jeff Layton Return-path: In-Reply-To: <20121003060410.07c30803-9yPaYZwiELC+kQycOl6kW4xkIHaj4LzF@public.gmane.org> Sender: linux-cifs-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-ID: On 10/03/2012 03:34 PM, Jeff Layton wrote: > On Wed, 03 Oct 2012 12:45:36 +0530 > Suresh Jayaraman wrote: > >> kernel_sendmsg() is less likely to return -ENOSPC and it might be >> a bug to do so. However, in the past there might have been cases >> where a -ENOSPC was returned from a low level driver. >> >> Add a WARN_ON_ONCE() to ensure that it is safe to assume that -ENOSPC >> is no longer returned. This -ENOSPC specific handling will be removed >> once we are sure it is no longer returned. >> >> Also, avoid setting -ENOSPC to -EAGAIN while at it. >> >> Cc: Jeff Layton >> Signed-off-by: Suresh Jayaraman >> --- >> fs/cifs/transport.c | 5 ++++- >> 1 file changed, 4 insertions(+), 1 deletion(-) >> >> diff --git a/fs/cifs/transport.c b/fs/cifs/transport.c >> index d9b639b..afe000f 100644 >> --- a/fs/cifs/transport.c >> +++ b/fs/cifs/transport.c >> @@ -155,6 +155,10 @@ smb_sendv(struct TCP_Server_Info *server, struct kvec *iov, int n_vec) >> rc = kernel_sendmsg(ssocket, &smb_msg, &iov[first_vec], >> n_vec - first_vec, total_len); >> if ((rc == -ENOSPC) || (rc == -EAGAIN)) { >> + /* >> + * Catch if a low level driver returns -ENOSPC. >> + */ >> + WARN_ON_ONCE(rc == -ENOSPC); >> i++; >> /* >> * If blocking send we try 3 times, since each can block >> @@ -177,7 +181,6 @@ smb_sendv(struct TCP_Server_Info *server, struct kvec *iov, int n_vec) >> if ((i >= 14) || (!server->noblocksnd && (i > 2))) { >> cERROR(1, "sends on sock %p stuck for 15 seconds", >> ssocket); >> - rc = -EAGAIN; > > Do you really want to remove this reset? This will change the behavior > if the lower levels do indeed return -ENOSPC. That will now bubble back > up to the upper levels and it will likely abort the call instead of > retrying. Yes, you are correct. I'll remove it. > > I think it would be best that we add the WARN_ON_ONCE but not change > anything else. If no one reports seeing that warning fire for 2 or 3 > releases then we can safely remove the -ENOSPC handling. Maybe shoot > for that in 3.10 or so? > > You may want to add a comment to remind us to revisit that for the 3.10 > cycle. > Sure, I'll add that when I respin. Thanks Suresh