Re: [Patch v2 2/2] CIFS: Fix an issue with re-sending rdata when transport returning -EAGAIN

Pavel Shilovsky
2019-03-16T18:03:49Z

пт, 15 мар. 2019 г. в 00:56, Long Li <longli@linuxonhyperv.com>:
>
> From: Long Li <longli@microsoft.com>
>
> When sending a rdata, transport may return -EAGAIN. In this case
> we should re-obtain credits because the session may have been
> reconnected.
>
> Change in v2: adjust_credits before re-sending
>
> Signed-off-by: Long Li <longli@microsoft.com>
> ---
> fs/cifs/file.c | 71 +++++++++++++++++++++++++++++++++-------------------------
> 1 file changed, 41 insertions(+), 30 deletions(-)
>
> diff --git a/fs/cifs/file.c b/fs/cifs/file.c
> index 321df1d27422..9d90cc07e38b 100644
> --- a/fs/cifs/file.c
> +++ b/fs/cifs/file.c
> @@ -3347,44 +3347,55 @@ static int cifs_resend_rdata(struct cifs_readdata *rdata,
> struct TCP_Server_Info *server =
> tlink_tcon(rdata->cfile->tlink)->ses->server;
>
> - /*
> - * Wait for credits to resend this rdata.
> - * Note: we are attempting to resend the whole rdata not in segments
> - */
> do {
> - rc = server->ops->wait_mtu_credits(server, rdata->bytes,
> + if (rdata->cfile->invalidHandle) {
> + rc = cifs_reopen_file(rdata->cfile, true);
> + if (rc == -EAGAIN)
> + continue;
> + else if (rc)
> + break;
> + }
> +
> + /*
> + * Wait for credits to resend this rdata.
> + * Note: we are attempting to resend the whole rdata not in
> + * segments
> + */
> + do {
> + rc = server->ops->wait_mtu_credits(server, rdata->bytes,
> &rsize, &credits);
>
> - if (rc)
> - goto out;
> + if (rc)
> + goto fail;
>
> - if (rsize < rdata->bytes) {
> - add_credits_and_wake_if(server, &credits, 0);
> - msleep(1000);
> - }
> - } while (rsize < rdata->bytes);
> + if (rsize < rdata->bytes) {
> + add_credits_and_wake_if(server, &credits, 0);
> + msleep(1000);
> + }
> + } while (rsize < rdata->bytes);
> + rdata->credits = credits;
>
> - rdata->credits = credits;
> - rc = -EAGAIN;
> - while (rc == -EAGAIN) {
> - rc = 0;
> - if (rdata->cfile->invalidHandle)
> - rc = cifs_reopen_file(rdata->cfile, true);
> - if (!rc)
> - rc = server->ops->async_readv(rdata);
> - }
> + rc = adjust_credits(server, &rdata->credits, rdata->bytes);
> + if (!rc) {
> + if (rdata->cfile->invalidHandle)
> + rc = -EAGAIN;
> + else
> + rc = server->ops->async_readv(rdata);
> + }
>
> - if (!rc) {
> - /* Add to aio pending list */
> - list_add_tail(&rdata->list, rdata_list);
> - return 0;
> - }
> + /* If the read was successfully sent, we are done */
> + if (!rc) {
> + /* Add to aio pending list */
> + list_add_tail(&rdata->list, rdata_list);
> + return 0;
> + }
>
> - add_credits_and_wake_if(server, &rdata->credits, 0);
> -out:
> - kref_put(&rdata->refcount,
> - cifs_uncached_readdata_release);
> + /* Roll back credits and retry if needed */
> + add_credits_and_wake_if(server, &rdata->credits, 0);
> + } while (rc == -EAGAIN);
>
> +fail:
> + kref_put(&rdata->refcount, cifs_uncached_readdata_release);
> return rc;
> }
>
> --
> 2.14.1
>

Reviewed-by: Pavel Shilovsky <pshilov@microsoft.com>

--
Best regards,
Pavel Shilovsky