On Wed, 03 Oct 2012 12:45:36 +0530
Suresh Jayaraman <sjayaraman@xxxxxxxx> 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 <jlayton@xxxxxxxxxx>
> Signed-off-by: Suresh Jayaraman <sjayaraman@xxxxxxxx>
> ---
> 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.
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.
> break;
> }
> msleep(1 << i);
--
Jeff Layton <jlayton@xxxxxxxxxx>
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