[PATCH AUTOSEL 4.20 39/42] CIFS: Fix credits calculation for cancelled requests

Sasha Levin
2019-02-09T18:55:31Z

From: Pavel Shilovsky <pshilov@microsoft.com>

[ Upstream commit 8a26f0f781f56d3016b34a2217e346973d067e7b ]

If a request is cancelled, we can't assume that the server returns
1 credit back. Instead we need to wait for a response and process
the number of credits granted by the server.

Create a separate mid callback for cancelled request, parse the number
of credits in a response buffer and add them to the client's credits.
If the didn't get a response (no response buffer available) assume
0 credits granted. The latter most probably happens together with
session reconnect, so the client's credits are adjusted anyway.

Signed-off-by: Pavel Shilovsky <pshilov@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
fs/cifs/cifsglob.h | 1 +
fs/cifs/transport.c | 28 ++++++++++++++++++++++++++--
2 files changed, 27 insertions(+), 2 deletions(-)

diff --git a/fs/cifs/cifsglob.h b/fs/cifs/cifsglob.h
index 38ab0fca49e1..7a4fae0dc566 100644
--- a/fs/cifs/cifsglob.h
+++ b/fs/cifs/cifsglob.h
@@ -1426,6 +1426,7 @@ struct mid_q_entry {
int mid_state; /* wish this were enum but can not pass to wait_event */
unsigned int mid_flags;
__le16 command; /* smb command code */
+ unsigned int optype; /* operation type */
bool large_buf:1; /* if valid response, is pointer to large buf */
bool multiRsp:1; /* multiple trans2 responses for one request */
bool multiEnd:1; /* both received */
diff --git a/fs/cifs/transport.c b/fs/cifs/transport.c
index d51064c1ba42..4dbf62bb51b2 100644
--- a/fs/cifs/transport.c
+++ b/fs/cifs/transport.c
@@ -785,6 +785,24 @@ cifs_noop_callback(struct mid_q_entry *mid)
{
}

+static void
+cifs_cancelled_callback(struct mid_q_entry *mid)
+{
+ struct TCP_Server_Info *server = mid->server;
+ unsigned int optype = mid->optype;
+ unsigned int credits_received = 0;
+
+ if (mid->mid_state == MID_RESPONSE_RECEIVED) {
+ if (mid->resp_buf)
+ credits_received = server->ops->get_credits(mid);
+ else
+ cifs_dbg(FYI, "Bad state for cancelled MID\n");
+ }
+
+ DeleteMidQEntry(mid);
+ add_credits(server, credits_received, optype);
+}
+
int
compound_send_recv(const unsigned int xid, struct cifs_ses *ses,
const int flags, const int num_rqst, struct smb_rqst *rqst,
@@ -860,6 +878,7 @@ compound_send_recv(const unsigned int xid, struct cifs_ses *ses,
}

midQ[i]->mid_state = MID_REQUEST_SUBMITTED;
+ midQ[i]->optype = optype;
/*
* We don't invoke the callback compounds unless it is the last
* request.
@@ -894,15 +913,20 @@ compound_send_recv(const unsigned int xid, struct cifs_ses *ses,

for (i = 0; i < num_rqst; i++) {
rc = wait_for_response(ses->server, midQ[i]);
- if (rc != 0) {
+ if (rc != 0)
+ break;
+ }
+ if (rc != 0) {
+ for (; i < num_rqst; i++) {
cifs_dbg(VFS, "Cancelling wait for mid %llu cmd: %d\n",
midQ[i]->mid, le16_to_cpu(midQ[i]->command));
send_cancel(ses->server, &rqst[i], midQ[i]);
spin_lock(&GlobalMid_Lock);
if (midQ[i]->mid_state == MID_REQUEST_SUBMITTED) {
midQ[i]->mid_flags |= MID_WAIT_CANCELLED;
- midQ[i]->callback = DeleteMidQEntry;
+ midQ[i]->callback = cifs_cancelled_callback;
cancelled_mid[i] = true;
+ credits[i] = 0;
}
spin_unlock(&GlobalMid_Lock);
}
--
2.19.1