2016-02-27 12:11 GMT+03:00 Pavel Shilovsky <pshilovsky@xxxxxxxxx>:
> 2016-02-23 15:55 GMT+03:00 Ira Cooper <ira@xxxxxxxxxxx>:
>>
>> If the server sends an interim response, then the real response, the real
>> response, is handled by standard_receive3() in the kernel, instead of the
>> proper function, and this causes a disconnect. If there isn't a
>> disconnect, I believe the reply will just be discarded if I understand the
>> code correctly. (That is a big if here ;) )
>>
>> I've written a patch for Samba to stop sending interim replies on
>> SMB2_READ
>> and SMB2_WRITE, when non-compounded to stop the impact of this issue. We
>> may want to add SMB2_CREATE to the list of ops we don't send async replies
>> for non-compounded, but I'm not sold either way, I know we CAN go async
>> there! I want some opinions here.
>>
>> This is not hidden behind a flag because compatibility issues that don't
>> impact protocol correctness usually aren't.
>>
>> Setting req->async_te = talloc_new(NULL); is just ugly, though it works.
>> If you have a cleaner approach, I welcome it.
>>
>> I request you please ASK me before pushing this one, yes, that means you
>> jra!
>>
>> For those interested in reproduction: I'd suggest using a server that's
>> rebuilt with a lower timeout set in smb2_read.c, though we've hit it with
>> vfs_glusterfs straight up, in our testing.
>>
>> Thanks,
>>
>> -Ira / ira@(samba.org|redhat.com|wakeful.net)
>
>
>
> Thank you for catching this!
>
> It is the issue in the kernel client - a check for interim responses is
> missed for SMB2_READ command. I created a patch that should fix the problem.
>
> Could you please test it?
>
> --
> Best regards,
> Pavel Shilovsky
CC'ing @samba-technical.
Sorry for the spam.
--
Best regards,
Pavel Shilovsky
From 09904bf0c6a1ecc7f61d4755db33b762b53176d6 Mon Sep 17 00:00:00 2001
From: Pavel Shilovsky <pshilovsky@xxxxxxxxx>
Date: Sat, 27 Feb 2016 11:58:18 +0300
Subject: [PATCH] CIFS: Fix SMB2+ interim response processing for read requests
For interim responses we only need to parse a header and update
a number credits. Now it is done for all SMB2+ command except
SMB2_READ which is wrong. Fix this by adding such processing.
Signed-off-by: Pavel Shilovsky <pshilovsky@xxxxxxxxx>
---
fs/cifs/cifssmb.c | 21 ++++++++++++++++++---
1 file changed, 18 insertions(+), 3 deletions(-)
diff --git a/fs/cifs/cifssmb.c b/fs/cifs/cifssmb.c
index 90b4f9f..76fcb50 100644
--- a/fs/cifs/cifssmb.c
+++ b/fs/cifs/cifssmb.c
@@ -1396,11 +1396,10 @@ openRetry:
* current bigbuf.
*/
static int
-cifs_readv_discard(struct TCP_Server_Info *server, struct mid_q_entry *mid)
+discard_remaining_data(struct TCP_Server_Info *server)
{
unsigned int rfclen = get_rfc1002_length(server->smallbuf);
int remaining = rfclen + 4 - server->total_read;
- struct cifs_readdata *rdata = mid->callback_data;
while (remaining > 0) {
int length;
@@ -1414,10 +1413,20 @@ cifs_readv_discard(struct TCP_Server_Info *server, struct mid_q_entry *mid)
remaining -= length;
}
- dequeue_mid(mid, rdata->result);
return 0;
}
+static int
+cifs_readv_discard(struct TCP_Server_Info *server, struct mid_q_entry *mid)
+{
+ int length;
+ struct cifs_readdata *rdata = mid->callback_data;
+
+ length = discard_remaining_data(server);
+ dequeue_mid(mid, rdata->result);
+ return length;
+}
+
int
cifs_readv_receive(struct TCP_Server_Info *server, struct mid_q_entry *mid)
{
@@ -1446,6 +1455,12 @@ cifs_readv_receive(struct TCP_Server_Info *server, struct mid_q_entry *mid)
return length;
server->total_read += length;
+ if (server->ops->is_status_pending &&
+ server->ops->is_status_pending(buf, server, 0)) {
+ discard_remaining_data(server);
+ return -1;
+ }
+
/* Was the SMB read successful? */
rdata->result = server->ops->map_error(buf, false);
if (rdata->result != 0) {
--
2.1.4
