[PATCH net 0/6] rxrpc, afs: Interruptibility fixes

[PATCH net 0/6] rxrpc, afs: Interruptibility fixes

[David Howells]

Here are a number of fixes for AF_RXRPC and AFS that make AFS system calls
less interruptible and so less likely to leave the filesystem in an
uncertain state.  There's also a miscellaneous patch to make tracing
consistent.

 (1) Firstly, abstract out the Tx space calculation in sendmsg.  Much the
     same code is replicated in a number of places that subsequent patches
     are going to alter, including adding another copy.

 (2) Fix Tx interruptibility by allowing a kernel service, such as AFS, to
     request that a call be interruptible only when waiting for a call slot
     to become available (ie. the call has not taken place yet) or that a
     call be not interruptible at all (e.g. when we want to do writeback
     and don't want a signal interrupting a VM-induced writeback).

 (3) Increase the minimum delay on MSG_WAITALL for userspace sendmsg() when
     waiting for Tx buffer space as a 2*RTT delay is really small over 10G
     ethernet and a 1 jiffy timeout might be essentially 0 if at the end of
     the jiffy period.

 (4) Fix some tracing output in AFS to make it consistent with rxrpc.

 (5) Make sure aborted asynchronous AFS operations are tidied up properly
     so we don't end up with stuck rxrpc calls.

 (6) Make AFS client calls uninterruptible in the Rx phase.  If we don't
     wait for the reply to be fully gathered, we can't update the local VFS
     state and we end up in an indeterminate state with respect to the
     server.

The patches are tagged here:

	git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs.git
	rxrpc-fixes-20200319

and can also be found on the following branch:

	http://git.kernel.org/cgit/linux/kernel/git/dhowells/linux-fs.git/log/?h=rxrpc-fixes

David
---
David Howells (6):
      rxrpc: Abstract out the calculation of whether there's Tx space
      rxrpc: Fix call interruptibility handling
      rxrpc: Fix sendmsg(MSG_WAITALL) handling
      afs: Fix some tracing details
      afs: Fix handling of an abort from a service handler
      afs: Fix client call Rx-phase signal handling


 fs/afs/cmservice.c         |   14 +++++++-
 fs/afs/internal.h          |   12 ++++++-
 fs/afs/rxrpc.c             |   74 ++++++-------------------------------------
 include/net/af_rxrpc.h     |   12 +++++--
 include/trace/events/afs.h |    2 +
 net/rxrpc/af_rxrpc.c       |   37 +++-------------------
 net/rxrpc/ar-internal.h    |    5 +--
 net/rxrpc/call_object.c    |    3 +-
 net/rxrpc/conn_client.c    |   13 ++++++--
 net/rxrpc/input.c          |    1 -
 net/rxrpc/sendmsg.c        |   75 +++++++++++++++++++++++++++++++++-----------
 11 files changed, 115 insertions(+), 133 deletions(-)

[PATCH net 1/6] rxrpc: Abstract out the calculation of whether there's Tx space

[David Howells]

Abstract out the calculation of there being sufficient Tx buffer space.
This is reproduced several times in the rxrpc sendmsg code.

Signed-off-by: David Howells <dhowells@redhat.com>
---

 net/rxrpc/sendmsg.c |   27 ++++++++++++++++++---------
 1 file changed, 18 insertions(+), 9 deletions(-)

diff --git a/net/rxrpc/sendmsg.c b/net/rxrpc/sendmsg.c
index 813fd6888142..a13051d38097 100644
--- a/net/rxrpc/sendmsg.c
+++ b/net/rxrpc/sendmsg.c
@@ -17,6 +17,21 @@
 #include <net/af_rxrpc.h>
 #include "ar-internal.h"
 
+/*
+ * Return true if there's sufficient Tx queue space.
+ */
+static bool rxrpc_check_tx_space(struct rxrpc_call *call, rxrpc_seq_t *_tx_win)
+{
+	unsigned int win_size =
+		min_t(unsigned int, call->tx_winsize,
+		      call->cong_cwnd + call->cong_extra);
+	rxrpc_seq_t tx_win = READ_ONCE(call->tx_hard_ack);
+
+	if (_tx_win)
+		*_tx_win = tx_win;
+	return call->tx_top - tx_win < win_size;
+}
+
 /*
  * Wait for space to appear in the Tx queue or a signal to occur.
  */
@@ -26,9 +41,7 @@ static int rxrpc_wait_for_tx_window_intr(struct rxrpc_sock *rx,
 {
 	for (;;) {
 		set_current_state(TASK_INTERRUPTIBLE);
-		if (call->tx_top - call->tx_hard_ack <
-		    min_t(unsigned int, call->tx_winsize,
-			  call->cong_cwnd + call->cong_extra))
+		if (rxrpc_check_tx_space(call, NULL))
 			return 0;
 
 		if (call->state >= RXRPC_CALL_COMPLETE)
@@ -68,9 +81,7 @@ static int rxrpc_wait_for_tx_window_nonintr(struct rxrpc_sock *rx,
 		set_current_state(TASK_UNINTERRUPTIBLE);
 
 		tx_win = READ_ONCE(call->tx_hard_ack);
-		if (call->tx_top - tx_win <
-		    min_t(unsigned int, call->tx_winsize,
-			  call->cong_cwnd + call->cong_extra))
+		if (rxrpc_check_tx_space(call, &tx_win))
 			return 0;
 
 		if (call->state >= RXRPC_CALL_COMPLETE)
@@ -302,9 +313,7 @@ static int rxrpc_send_data(struct rxrpc_sock *rx,
 
 			_debug("alloc");
 
-			if (call->tx_top - call->tx_hard_ack >=
-			    min_t(unsigned int, call->tx_winsize,
-				  call->cong_cwnd + call->cong_extra)) {
+			if (!rxrpc_check_tx_space(call, NULL)) {
 				ret = -EAGAIN;
 				if (msg->msg_flags & MSG_DONTWAIT)
 					goto maybe_error;

[PATCH net 2/6] rxrpc: Fix call interruptibility handling

[David Howells]

Fix the interruptibility of kernel-initiated client calls so that they're
either only interruptible when they're waiting for a call slot to come
available or they're not interruptible at all.  Either way, they're not
interruptible during transmission.

This should help prevent StoreData calls from being interrupted when
writeback is in progress.  It doesn't, however, handle interruption during
the receive phase.

Userspace-initiated calls are still interruptable.  After the signal has
been handled, sendmsg() will return the amount of data copied out of the
buffer and userspace can perform another sendmsg() call to continue
transmission.

Fixes: bc5e3a546d55 ("rxrpc: Use MSG_WAITALL to tell sendmsg() to temporarily ignore signals")
Signed-off-by: David Howells <dhowells@redhat.com>
---

 fs/afs/rxrpc.c          |    3 ++-
 include/net/af_rxrpc.h  |    8 +++++++-
 net/rxrpc/af_rxrpc.c    |    4 ++--
 net/rxrpc/ar-internal.h |    4 ++--
 net/rxrpc/call_object.c |    3 +--
 net/rxrpc/conn_client.c |   13 ++++++++++---
 net/rxrpc/sendmsg.c     |   44 ++++++++++++++++++++++++++++++++++++--------
 7 files changed, 60 insertions(+), 19 deletions(-)

diff --git a/fs/afs/rxrpc.c b/fs/afs/rxrpc.c
index 58d396592250..4c28712bb7f6 100644
--- a/fs/afs/rxrpc.c
+++ b/fs/afs/rxrpc.c
@@ -413,7 +413,8 @@ void afs_make_call(struct afs_addr_cursor *ac, struct afs_call *call, gfp_t gfp)
 					  afs_wake_up_async_call :
 					  afs_wake_up_call_waiter),
 					 call->upgrade,
-					 call->intr,
+					 (call->intr ? RXRPC_PREINTERRUPTIBLE :
+					  RXRPC_UNINTERRUPTIBLE),
 					 call->debug_id);
 	if (IS_ERR(rxcall)) {
 		ret = PTR_ERR(rxcall);
diff --git a/include/net/af_rxrpc.h b/include/net/af_rxrpc.h
index 1abae3c340a5..8e547b4d88c8 100644
--- a/include/net/af_rxrpc.h
+++ b/include/net/af_rxrpc.h
@@ -16,6 +16,12 @@ struct sock;
 struct socket;
 struct rxrpc_call;
 
+enum rxrpc_interruptibility {
+	RXRPC_INTERRUPTIBLE,	/* Call is interruptible */
+	RXRPC_PREINTERRUPTIBLE,	/* Call can be cancelled whilst waiting for a slot */
+	RXRPC_UNINTERRUPTIBLE,	/* Call should not be interruptible at all */
+};
+
 /*
  * Debug ID counter for tracing.
  */
@@ -41,7 +47,7 @@ struct rxrpc_call *rxrpc_kernel_begin_call(struct socket *,
 					   gfp_t,
 					   rxrpc_notify_rx_t,
 					   bool,
-					   bool,
+					   enum rxrpc_interruptibility,
 					   unsigned int);
 int rxrpc_kernel_send_data(struct socket *, struct rxrpc_call *,
 			   struct msghdr *, size_t,
diff --git a/net/rxrpc/af_rxrpc.c b/net/rxrpc/af_rxrpc.c
index fe42f986cd94..7603cf811f75 100644
--- a/net/rxrpc/af_rxrpc.c
+++ b/net/rxrpc/af_rxrpc.c
@@ -285,7 +285,7 @@ struct rxrpc_call *rxrpc_kernel_begin_call(struct socket *sock,
 					   gfp_t gfp,
 					   rxrpc_notify_rx_t notify_rx,
 					   bool upgrade,
-					   bool intr,
+					   enum rxrpc_interruptibility interruptibility,
 					   unsigned int debug_id)
 {
 	struct rxrpc_conn_parameters cp;
@@ -310,7 +310,7 @@ struct rxrpc_call *rxrpc_kernel_begin_call(struct socket *sock,
 	memset(&p, 0, sizeof(p));
 	p.user_call_ID = user_call_ID;
 	p.tx_total_len = tx_total_len;
-	p.intr = intr;
+	p.interruptibility = interruptibility;
 
 	memset(&cp, 0, sizeof(cp));
 	cp.local		= rx->local;
diff --git a/net/rxrpc/ar-internal.h b/net/rxrpc/ar-internal.h
index 7d730c438404..1f72f43b082d 100644
--- a/net/rxrpc/ar-internal.h
+++ b/net/rxrpc/ar-internal.h
@@ -489,7 +489,6 @@ enum rxrpc_call_flag {
 	RXRPC_CALL_BEGAN_RX_TIMER,	/* We began the expect_rx_by timer */
 	RXRPC_CALL_RX_HEARD,		/* The peer responded at least once to this call */
 	RXRPC_CALL_RX_UNDERRUN,		/* Got data underrun */
-	RXRPC_CALL_IS_INTR,		/* The call is interruptible */
 	RXRPC_CALL_DISCONNECTED,	/* The call has been disconnected */
 };
 
@@ -598,6 +597,7 @@ struct rxrpc_call {
 	atomic_t		usage;
 	u16			service_id;	/* service ID */
 	u8			security_ix;	/* Security type */
+	enum rxrpc_interruptibility interruptibility; /* At what point call may be interrupted */
 	u32			call_id;	/* call ID on connection  */
 	u32			cid;		/* connection ID plus channel index */
 	int			debug_id;	/* debug ID for printks */
@@ -721,7 +721,7 @@ struct rxrpc_call_params {
 		u32		normal;		/* Max time since last call packet (msec) */
 	} timeouts;
 	u8			nr_timeouts;	/* Number of timeouts specified */
-	bool			intr;		/* The call is interruptible */
+	enum rxrpc_interruptibility interruptibility; /* How is interruptible is the call? */
 };
 
 struct rxrpc_send_params {
diff --git a/net/rxrpc/call_object.c b/net/rxrpc/call_object.c
index c9f34b0a11df..f07970207b54 100644
--- a/net/rxrpc/call_object.c
+++ b/net/rxrpc/call_object.c
@@ -237,8 +237,7 @@ struct rxrpc_call *rxrpc_new_client_call(struct rxrpc_sock *rx,
 		return call;
 	}
 
-	if (p->intr)
-		__set_bit(RXRPC_CALL_IS_INTR, &call->flags);
+	call->interruptibility = p->interruptibility;
 	call->tx_total_len = p->tx_total_len;
 	trace_rxrpc_call(call->debug_id, rxrpc_call_new_client,
 			 atomic_read(&call->usage),
diff --git a/net/rxrpc/conn_client.c b/net/rxrpc/conn_client.c
index ea7d4c21f889..f2a1a5dbb5a7 100644
--- a/net/rxrpc/conn_client.c
+++ b/net/rxrpc/conn_client.c
@@ -655,13 +655,20 @@ static int rxrpc_wait_for_channel(struct rxrpc_call *call, gfp_t gfp)
 
 		add_wait_queue_exclusive(&call->waitq, &myself);
 		for (;;) {
-			if (test_bit(RXRPC_CALL_IS_INTR, &call->flags))
+			switch (call->interruptibility) {
+			case RXRPC_INTERRUPTIBLE:
+			case RXRPC_PREINTERRUPTIBLE:
 				set_current_state(TASK_INTERRUPTIBLE);
-			else
+				break;
+			case RXRPC_UNINTERRUPTIBLE:
+			default:
 				set_current_state(TASK_UNINTERRUPTIBLE);
+				break;
+			}
 			if (call->call_id)
 				break;
-			if (test_bit(RXRPC_CALL_IS_INTR, &call->flags) &&
+			if ((call->interruptibility == RXRPC_INTERRUPTIBLE ||
+			     call->interruptibility == RXRPC_PREINTERRUPTIBLE) &&
 			    signal_pending(current)) {
 				ret = -ERESTARTSYS;
 				break;
diff --git a/net/rxrpc/sendmsg.c b/net/rxrpc/sendmsg.c
index a13051d38097..1eccfb92c9e1 100644
--- a/net/rxrpc/sendmsg.c
+++ b/net/rxrpc/sendmsg.c
@@ -62,7 +62,7 @@ static int rxrpc_wait_for_tx_window_intr(struct rxrpc_sock *rx,
  * Wait for space to appear in the Tx queue uninterruptibly, but with
  * a timeout of 2*RTT if no progress was made and a signal occurred.
  */
-static int rxrpc_wait_for_tx_window_nonintr(struct rxrpc_sock *rx,
+static int rxrpc_wait_for_tx_window_waitall(struct rxrpc_sock *rx,
 					    struct rxrpc_call *call)
 {
 	rxrpc_seq_t tx_start, tx_win;
@@ -87,8 +87,7 @@ static int rxrpc_wait_for_tx_window_nonintr(struct rxrpc_sock *rx,
 		if (call->state >= RXRPC_CALL_COMPLETE)
 			return call->error;
 
-		if (test_bit(RXRPC_CALL_IS_INTR, &call->flags) &&
-		    timeout == 0 &&
+		if (timeout == 0 &&
 		    tx_win == tx_start && signal_pending(current))
 			return -EINTR;
 
@@ -102,6 +101,26 @@ static int rxrpc_wait_for_tx_window_nonintr(struct rxrpc_sock *rx,
 	}
 }
 
+/*
+ * Wait for space to appear in the Tx queue uninterruptibly.
+ */
+static int rxrpc_wait_for_tx_window_nonintr(struct rxrpc_sock *rx,
+					    struct rxrpc_call *call,
+					    long *timeo)
+{
+	for (;;) {
+		set_current_state(TASK_UNINTERRUPTIBLE);
+		if (rxrpc_check_tx_space(call, NULL))
+			return 0;
+
+		if (call->state >= RXRPC_CALL_COMPLETE)
+			return call->error;
+
+		trace_rxrpc_transmit(call, rxrpc_transmit_wait);
+		*timeo = schedule_timeout(*timeo);
+	}
+}
+
 /*
  * wait for space to appear in the transmit/ACK window
  * - caller holds the socket locked
@@ -119,10 +138,19 @@ static int rxrpc_wait_for_tx_window(struct rxrpc_sock *rx,
 
 	add_wait_queue(&call->waitq, &myself);
 
-	if (waitall)
-		ret = rxrpc_wait_for_tx_window_nonintr(rx, call);
-	else
-		ret = rxrpc_wait_for_tx_window_intr(rx, call, timeo);
+	switch (call->interruptibility) {
+	case RXRPC_INTERRUPTIBLE:
+		if (waitall)
+			ret = rxrpc_wait_for_tx_window_waitall(rx, call);
+		else
+			ret = rxrpc_wait_for_tx_window_intr(rx, call, timeo);
+		break;
+	case RXRPC_PREINTERRUPTIBLE:
+	case RXRPC_UNINTERRUPTIBLE:
+	default:
+		ret = rxrpc_wait_for_tx_window_nonintr(rx, call, timeo);
+		break;
+	}
 
 	remove_wait_queue(&call->waitq, &myself);
 	set_current_state(TASK_RUNNING);
@@ -628,7 +656,7 @@ int rxrpc_do_sendmsg(struct rxrpc_sock *rx, struct msghdr *msg, size_t len)
 		.call.tx_total_len	= -1,
 		.call.user_call_ID	= 0,
 		.call.nr_timeouts	= 0,
-		.call.intr		= true,
+		.call.interruptibility	= RXRPC_INTERRUPTIBLE,
 		.abort_code		= 0,
 		.command		= RXRPC_CMD_SEND_DATA,
 		.exclusive		= false,

[PATCH net 3/6] rxrpc: Fix sendmsg(MSG_WAITALL) handling

[David Howells]

Fix the handling of sendmsg() with MSG_WAITALL for userspace to round the
timeout for when a signal occurs up to at least two jiffies as a 1 jiffy
timeout may end up being effectively 0 if jiffies wraps at the wrong time.

Fixes: bc5e3a546d55 ("rxrpc: Use MSG_WAITALL to tell sendmsg() to temporarily ignore signals")
Signed-off-by: David Howells <dhowells@redhat.com>
---

 net/rxrpc/sendmsg.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/net/rxrpc/sendmsg.c b/net/rxrpc/sendmsg.c
index 1eccfb92c9e1..0fcf157aa09f 100644
--- a/net/rxrpc/sendmsg.c
+++ b/net/rxrpc/sendmsg.c
@@ -71,8 +71,8 @@ static int rxrpc_wait_for_tx_window_waitall(struct rxrpc_sock *rx,
 
 	rtt = READ_ONCE(call->peer->rtt);
 	rtt2 = nsecs_to_jiffies64(rtt) * 2;
-	if (rtt2 < 1)
-		rtt2 = 1;
+	if (rtt2 < 2)
+		rtt2 = 2;
 
 	timeout = rtt2;
 	tx_start = READ_ONCE(call->tx_hard_ack);

[PATCH net 4/6] afs: Fix some tracing details

[David Howells]

Fix a couple of tracelines to indicate the usage count after the atomic op,
not the usage count before it to be consistent with other afs and rxrpc
trace lines.

Change the wording of the afs_call_trace_work trace ID label from "WORK" to
"QUEUE" to reflect the fact that it's queueing work, not doing work.

Fixes: 341f741f04be ("afs: Refcount the afs_call struct")
Signed-off-by: David Howells <dhowells@redhat.com>
---

 fs/afs/rxrpc.c             |    4 ++--
 include/trace/events/afs.h |    2 +-
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/fs/afs/rxrpc.c b/fs/afs/rxrpc.c
index 4c28712bb7f6..907d5948564a 100644
--- a/fs/afs/rxrpc.c
+++ b/fs/afs/rxrpc.c
@@ -169,7 +169,7 @@ void afs_put_call(struct afs_call *call)
 	int n = atomic_dec_return(&call->usage);
 	int o = atomic_read(&net->nr_outstanding_calls);
 
-	trace_afs_call(call, afs_call_trace_put, n + 1, o,
+	trace_afs_call(call, afs_call_trace_put, n, o,
 		       __builtin_return_address(0));
 
 	ASSERTCMP(n, >=, 0);
@@ -736,7 +736,7 @@ static void afs_wake_up_async_call(struct sock *sk, struct rxrpc_call *rxcall,
 
 	u = atomic_fetch_add_unless(&call->usage, 1, 0);
 	if (u != 0) {
-		trace_afs_call(call, afs_call_trace_wake, u,
+		trace_afs_call(call, afs_call_trace_wake, u + 1,
 			       atomic_read(&call->net->nr_outstanding_calls),
 			       __builtin_return_address(0));
 
diff --git a/include/trace/events/afs.h b/include/trace/events/afs.h
index 564ba1b5cf57..c612cabbc378 100644
--- a/include/trace/events/afs.h
+++ b/include/trace/events/afs.h
@@ -233,7 +233,7 @@ enum afs_cb_break_reason {
 	EM(afs_call_trace_get,			"GET  ") \
 	EM(afs_call_trace_put,			"PUT  ") \
 	EM(afs_call_trace_wake,			"WAKE ") \
-	E_(afs_call_trace_work,			"WORK ")
+	E_(afs_call_trace_work,			"QUEUE")
 
 #define afs_server_traces \
 	EM(afs_server_trace_alloc,		"ALLOC    ") \

[PATCH net 5/6] afs: Fix handling of an abort from a service handler

[David Howells]

When an AFS service handler function aborts a call, AF_RXRPC marks the call
as complete - which means that it's not going to get any more packets from
the receiver.  This is a problem because reception of the final ACK is what
triggers afs_deliver_to_call() to drop the final ref on the afs_call
object.

Instead, aborted AFS service calls may then just sit around waiting for
ever or until they're displaced by a new call on the same connection
channel or a connection-level abort.

Fix this by calling afs_set_call_complete() to finalise the afs_call struct
representing the call.

However, we then need to drop the ref that stops the call from being
deallocated.  We can do this in afs_set_call_complete(), as the work queue
is holding a separate ref of its own, but then we shouldn't do it in
afs_process_async_call() and afs_delete_async_call().

call->drop_ref is set to indicate that a ref needs dropping for a call and
this is dealt with when we transition a call to AFS_CALL_COMPLETE.

But then we also need to get rid of the ref that pins an asynchronous
client call.  We can do this by the same mechanism, setting call->drop_ref
for an async client call too.

We can also get rid of call->incoming since nothing ever sets it and only
one thing ever checks it (futilely).


A trace of the rxrpc_call and afs_call struct ref counting looks like:

          <idle>-0     [001] ..s5   164.764892: rxrpc_call: c=00000002 SEE u=3 sp=rxrpc_new_incoming_call+0x473/0xb34 a=00000000442095b5
          <idle>-0     [001] .Ns5   164.766001: rxrpc_call: c=00000002 QUE u=4 sp=rxrpc_propose_ACK+0xbe/0x551 a=00000000442095b5
          <idle>-0     [001] .Ns4   164.766005: rxrpc_call: c=00000002 PUT u=3 sp=rxrpc_new_incoming_call+0xa3f/0xb34 a=00000000442095b5
          <idle>-0     [001] .Ns7   164.766433: afs_call: c=00000002 WAKE  u=2 o=11 sp=rxrpc_notify_socket+0x196/0x33c
     kworker/1:2-1810  [001] ...1   164.768409: rxrpc_call: c=00000002 SEE u=3 sp=rxrpc_process_call+0x25/0x7ae a=00000000442095b5
     kworker/1:2-1810  [001] ...1   164.769439: rxrpc_tx_packet: c=00000002 e9f1a7a8:95786a88:00000008:09c5 00000001 00000000 02 22 ACK CallAck
     kworker/1:2-1810  [001] ...1   164.769459: rxrpc_call: c=00000002 PUT u=2 sp=rxrpc_process_call+0x74f/0x7ae a=00000000442095b5
     kworker/1:2-1810  [001] ...1   164.770794: afs_call: c=00000002 QUEUE u=3 o=12 sp=afs_deliver_to_call+0x449/0x72c
     kworker/1:2-1810  [001] ...1   164.770829: afs_call: c=00000002 PUT   u=2 o=12 sp=afs_process_async_call+0xdb/0x11e
     kworker/1:2-1810  [001] ...2   164.771084: rxrpc_abort: c=00000002 95786a88:00000008 s=0 a=1 e=1 K-1
     kworker/1:2-1810  [001] ...1   164.771461: rxrpc_tx_packet: c=00000002 e9f1a7a8:95786a88:00000008:09c5 00000002 00000000 04 00 ABORT CallAbort
     kworker/1:2-1810  [001] ...1   164.771466: afs_call: c=00000002 PUT   u=1 o=12 sp=SRXAFSCB_ProbeUuid+0xc1/0x106

The abort generated in SRXAFSCB_ProbeUuid(), labelled "K-1", indicates that
the local filesystem/cache manager didn't recognise the UUID as its own.

Fixes: 2067b2b3f484 ("afs: Fix the CB.ProbeUuid service handler to reply correctly")
Signed-off-by: David Howells <dhowells@redhat.com>
---

 fs/afs/cmservice.c |   14 ++++++++++++--
 fs/afs/internal.h  |   12 ++++++++++--
 fs/afs/rxrpc.c     |   33 ++++-----------------------------
 3 files changed, 26 insertions(+), 33 deletions(-)

diff --git a/fs/afs/cmservice.c b/fs/afs/cmservice.c
index ff3994a6be23..6765949b3aab 100644
--- a/fs/afs/cmservice.c
+++ b/fs/afs/cmservice.c
@@ -243,6 +243,17 @@ static void afs_cm_destructor(struct afs_call *call)
 	call->buffer = NULL;
 }
 
+/*
+ * Abort a service call from within an action function.
+ */
+static void afs_abort_service_call(struct afs_call *call, u32 abort_code, int error,
+				   const char *why)
+{
+	rxrpc_kernel_abort_call(call->net->socket, call->rxcall,
+				abort_code, error, why);
+	afs_set_call_complete(call, error, 0);
+}
+
 /*
  * The server supplied a list of callbacks that it wanted to break.
  */
@@ -510,8 +521,7 @@ static void SRXAFSCB_ProbeUuid(struct work_struct *work)
 	if (memcmp(r, &call->net->uuid, sizeof(call->net->uuid)) == 0)
 		afs_send_empty_reply(call);
 	else
-		rxrpc_kernel_abort_call(call->net->socket, call->rxcall,
-					1, 1, "K-1");
+		afs_abort_service_call(call, 1, 1, "K-1");
 
 	afs_put_call(call);
 	_leave("");
diff --git a/fs/afs/internal.h b/fs/afs/internal.h
index 1d81fc4c3058..52de2112e1b1 100644
--- a/fs/afs/internal.h
+++ b/fs/afs/internal.h
@@ -154,7 +154,7 @@ struct afs_call {
 	};
 	unsigned char		unmarshall;	/* unmarshalling phase */
 	unsigned char		addr_ix;	/* Address in ->alist */
-	bool			incoming;	/* T if incoming call */
+	bool			drop_ref;	/* T if need to drop ref for incoming call */
 	bool			send_pages;	/* T if data from mapping should be sent */
 	bool			need_attention;	/* T if RxRPC poked us */
 	bool			async;		/* T if asynchronous */
@@ -1209,8 +1209,16 @@ static inline void afs_set_call_complete(struct afs_call *call,
 		ok = true;
 	}
 	spin_unlock_bh(&call->state_lock);
-	if (ok)
+	if (ok) {
 		trace_afs_call_done(call);
+
+		/* Asynchronous calls have two refs to release - one from the alloc and
+		 * one queued with the work item - and we can't just deallocate the
+		 * call because the work item may be queued again.
+		 */
+		if (call->drop_ref)
+			afs_put_call(call);
+	}
 }
 
 /*
diff --git a/fs/afs/rxrpc.c b/fs/afs/rxrpc.c
index 907d5948564a..972e3aafa361 100644
--- a/fs/afs/rxrpc.c
+++ b/fs/afs/rxrpc.c
@@ -18,7 +18,6 @@ struct workqueue_struct *afs_async_calls;
 
 static void afs_wake_up_call_waiter(struct sock *, struct rxrpc_call *, unsigned long);
 static void afs_wake_up_async_call(struct sock *, struct rxrpc_call *, unsigned long);
-static void afs_delete_async_call(struct work_struct *);
 static void afs_process_async_call(struct work_struct *);
 static void afs_rx_new_call(struct sock *, struct rxrpc_call *, unsigned long);
 static void afs_rx_discard_new_call(struct rxrpc_call *, unsigned long);
@@ -402,8 +401,10 @@ void afs_make_call(struct afs_addr_cursor *ac, struct afs_call *call, gfp_t gfp)
 	/* If the call is going to be asynchronous, we need an extra ref for
 	 * the call to hold itself so the caller need not hang on to its ref.
 	 */
-	if (call->async)
+	if (call->async) {
 		afs_get_call(call, afs_call_trace_get);
+		call->drop_ref = true;
+	}
 
 	/* create a call */
 	rxcall = rxrpc_kernel_begin_call(call->net->socket, srx, call->key,
@@ -585,8 +586,6 @@ static void afs_deliver_to_call(struct afs_call *call)
 done:
 	if (call->type->done)
 		call->type->done(call);
-	if (state == AFS_CALL_COMPLETE && call->incoming)
-		afs_put_call(call);
 out:
 	_leave("");
 	return;
@@ -745,21 +744,6 @@ static void afs_wake_up_async_call(struct sock *sk, struct rxrpc_call *rxcall,
 	}
 }
 
-/*
- * Delete an asynchronous call.  The work item carries a ref to the call struct
- * that we need to release.
- */
-static void afs_delete_async_call(struct work_struct *work)
-{
-	struct afs_call *call = container_of(work, struct afs_call, async_work);
-
-	_enter("");
-
-	afs_put_call(call);
-
-	_leave("");
-}
-
 /*
  * Perform I/O processing on an asynchronous call.  The work item carries a ref
  * to the call struct that we either need to release or to pass on.
@@ -775,16 +759,6 @@ static void afs_process_async_call(struct work_struct *work)
 		afs_deliver_to_call(call);
 	}
 
-	if (call->state == AFS_CALL_COMPLETE) {
-		/* We have two refs to release - one from the alloc and one
-		 * queued with the work item - and we can't just deallocate the
-		 * call because the work item may be queued again.
-		 */
-		call->async_work.func = afs_delete_async_call;
-		if (!queue_work(afs_async_calls, &call->async_work))
-			afs_put_call(call);
-	}
-
 	afs_put_call(call);
 	_leave("");
 }
@@ -811,6 +785,7 @@ void afs_charge_preallocation(struct work_struct *work)
 			if (!call)
 				break;
 
+			call->drop_ref = true;
 			call->async = true;
 			call->state = AFS_CALL_SV_AWAIT_OP_ID;
 			init_waitqueue_head(&call->waitq);

[PATCH net 6/6] afs: Fix client call Rx-phase signal handling

[David Howells]

Fix the handling of signals in client rxrpc calls made by the afs
filesystem.  Ignore signals completely, leaving call abandonment or
connection loss to be detected by timeouts inside AF_RXRPC.

Allowing a filesystem call to be interrupted after the entire request has
been transmitted and an abort sent means that the server may or may not
have done the action - and we don't know.  It may even be worse than that
for older servers.

Fixes: bc5e3a546d55 ("rxrpc: Use MSG_WAITALL to tell sendmsg() to temporarily ignore signals")
Signed-off-by: David Howells <dhowells@redhat.com>
---

 fs/afs/rxrpc.c          |   34 ++--------------------------------
 include/net/af_rxrpc.h  |    4 +---
 net/rxrpc/af_rxrpc.c    |   33 +++------------------------------
 net/rxrpc/ar-internal.h |    1 -
 net/rxrpc/input.c       |    1 -
 5 files changed, 6 insertions(+), 67 deletions(-)

diff --git a/fs/afs/rxrpc.c b/fs/afs/rxrpc.c
index 972e3aafa361..1ecc67da6c1a 100644
--- a/fs/afs/rxrpc.c
+++ b/fs/afs/rxrpc.c
@@ -604,11 +604,7 @@ static void afs_deliver_to_call(struct afs_call *call)
 long afs_wait_for_call_to_complete(struct afs_call *call,
 				   struct afs_addr_cursor *ac)
 {
-	signed long rtt2, timeout;
 	long ret;
-	bool stalled = false;
-	u64 rtt;
-	u32 life, last_life;
 	bool rxrpc_complete = false;
 
 	DECLARE_WAITQUEUE(myself, current);
@@ -619,14 +615,6 @@ long afs_wait_for_call_to_complete(struct afs_call *call,
 	if (ret < 0)
 		goto out;
 
-	rtt = rxrpc_kernel_get_rtt(call->net->socket, call->rxcall);
-	rtt2 = nsecs_to_jiffies64(rtt) * 2;
-	if (rtt2 < 2)
-		rtt2 = 2;
-
-	timeout = rtt2;
-	rxrpc_kernel_check_life(call->net->socket, call->rxcall, &last_life);
-
 	add_wait_queue(&call->waitq, &myself);
 	for (;;) {
 		set_current_state(TASK_UNINTERRUPTIBLE);
@@ -637,37 +625,19 @@ long afs_wait_for_call_to_complete(struct afs_call *call,
 			call->need_attention = false;
 			__set_current_state(TASK_RUNNING);
 			afs_deliver_to_call(call);
-			timeout = rtt2;
 			continue;
 		}
 
 		if (afs_check_call_state(call, AFS_CALL_COMPLETE))
 			break;
 
-		if (!rxrpc_kernel_check_life(call->net->socket, call->rxcall, &life)) {
+		if (!rxrpc_kernel_check_life(call->net->socket, call->rxcall)) {
 			/* rxrpc terminated the call. */
 			rxrpc_complete = true;
 			break;
 		}
 
-		if (call->intr && timeout == 0 &&
-		    life == last_life && signal_pending(current)) {
-			if (stalled)
-				break;
-			__set_current_state(TASK_RUNNING);
-			rxrpc_kernel_probe_life(call->net->socket, call->rxcall);
-			timeout = rtt2;
-			stalled = true;
-			continue;
-		}
-
-		if (life != last_life) {
-			timeout = rtt2;
-			last_life = life;
-			stalled = false;
-		}
-
-		timeout = schedule_timeout(timeout);
+		schedule();
 	}
 
 	remove_wait_queue(&call->waitq, &myself);
diff --git a/include/net/af_rxrpc.h b/include/net/af_rxrpc.h
index 8e547b4d88c8..04e97bab6f28 100644
--- a/include/net/af_rxrpc.h
+++ b/include/net/af_rxrpc.h
@@ -64,9 +64,7 @@ int rxrpc_kernel_charge_accept(struct socket *, rxrpc_notify_rx_t,
 			       rxrpc_user_attach_call_t, unsigned long, gfp_t,
 			       unsigned int);
 void rxrpc_kernel_set_tx_length(struct socket *, struct rxrpc_call *, s64);
-bool rxrpc_kernel_check_life(const struct socket *, const struct rxrpc_call *,
-			     u32 *);
-void rxrpc_kernel_probe_life(struct socket *, struct rxrpc_call *);
+bool rxrpc_kernel_check_life(const struct socket *, const struct rxrpc_call *);
 u32 rxrpc_kernel_get_epoch(struct socket *, struct rxrpc_call *);
 bool rxrpc_kernel_get_reply_time(struct socket *, struct rxrpc_call *,
 				 ktime_t *);
diff --git a/net/rxrpc/af_rxrpc.c b/net/rxrpc/af_rxrpc.c
index 7603cf811f75..15ee92d79581 100644
--- a/net/rxrpc/af_rxrpc.c
+++ b/net/rxrpc/af_rxrpc.c
@@ -371,44 +371,17 @@ EXPORT_SYMBOL(rxrpc_kernel_end_call);
  * rxrpc_kernel_check_life - Check to see whether a call is still alive
  * @sock: The socket the call is on
  * @call: The call to check
- * @_life: Where to store the life value
  *
- * Allow a kernel service to find out whether a call is still alive - ie. we're
- * getting ACKs from the server.  Passes back in *_life a number representing
- * the life state which can be compared to that returned by a previous call and
- * return true if the call is still alive.
- *
- * If the life state stalls, rxrpc_kernel_probe_life() should be called and
- * then 2RTT waited.
+ * Allow a kernel service to find out whether a call is still alive -
+ * ie. whether it has completed.
  */
 bool rxrpc_kernel_check_life(const struct socket *sock,
-			     const struct rxrpc_call *call,
-			     u32 *_life)
+			     const struct rxrpc_call *call)
 {
-	*_life = call->acks_latest;
 	return call->state != RXRPC_CALL_COMPLETE;
 }
 EXPORT_SYMBOL(rxrpc_kernel_check_life);
 
-/**
- * rxrpc_kernel_probe_life - Poke the peer to see if it's still alive
- * @sock: The socket the call is on
- * @call: The call to check
- *
- * In conjunction with rxrpc_kernel_check_life(), allow a kernel service to
- * find out whether a call is still alive by pinging it.  This should cause the
- * life state to be bumped in about 2*RTT.
- *
- * The must be called in TASK_RUNNING state on pain of might_sleep() objecting.
- */
-void rxrpc_kernel_probe_life(struct socket *sock, struct rxrpc_call *call)
-{
-	rxrpc_propose_ACK(call, RXRPC_ACK_PING, 0, true, false,
-			  rxrpc_propose_ack_ping_for_check_life);
-	rxrpc_send_ack_packet(call, true, NULL);
-}
-EXPORT_SYMBOL(rxrpc_kernel_probe_life);
-
 /**
  * rxrpc_kernel_get_epoch - Retrieve the epoch value from a call.
  * @sock: The socket the call is on
diff --git a/net/rxrpc/ar-internal.h b/net/rxrpc/ar-internal.h
index 1f72f43b082d..3eb1ab40ca5c 100644
--- a/net/rxrpc/ar-internal.h
+++ b/net/rxrpc/ar-internal.h
@@ -675,7 +675,6 @@ struct rxrpc_call {
 
 	/* transmission-phase ACK management */
 	ktime_t			acks_latest_ts;	/* Timestamp of latest ACK received */
-	rxrpc_serial_t		acks_latest;	/* serial number of latest ACK received */
 	rxrpc_seq_t		acks_lowest_nak; /* Lowest NACK in the buffer (or ==tx_hard_ack) */
 	rxrpc_seq_t		acks_lost_top;	/* tx_top at the time lost-ack ping sent */
 	rxrpc_serial_t		acks_lost_ping;	/* Serial number of probe ACK */
diff --git a/net/rxrpc/input.c b/net/rxrpc/input.c
index ef10fbf71b15..69e09d69c896 100644
--- a/net/rxrpc/input.c
+++ b/net/rxrpc/input.c
@@ -882,7 +882,6 @@ static void rxrpc_input_ack(struct rxrpc_call *call, struct sk_buff *skb)
 	    before(prev_pkt, call->ackr_prev_seq))
 		goto out;
 	call->acks_latest_ts = skb->tstamp;
-	call->acks_latest = sp->hdr.serial;
 
 	call->ackr_first_seq = first_soft_ack;
 	call->ackr_prev_seq = prev_pkt;

Re: [PATCH net 0/6] rxrpc, afs: Interruptibility fixes

[David Miller]

From: David Howells <dhowells@redhat.com>
Date: Thu, 19 Mar 2020 11:53:29 +0000

> Here are a number of fixes for AF_RXRPC and AFS that make AFS system calls
> less interruptible and so less likely to leave the filesystem in an
> uncertain state.  There's also a miscellaneous patch to make tracing
> consistent.
> 
>  (1) Firstly, abstract out the Tx space calculation in sendmsg.  Much the
>      same code is replicated in a number of places that subsequent patches
>      are going to alter, including adding another copy.
> 
>  (2) Fix Tx interruptibility by allowing a kernel service, such as AFS, to
>      request that a call be interruptible only when waiting for a call slot
>      to become available (ie. the call has not taken place yet) or that a
>      call be not interruptible at all (e.g. when we want to do writeback
>      and don't want a signal interrupting a VM-induced writeback).
> 
>  (3) Increase the minimum delay on MSG_WAITALL for userspace sendmsg() when
>      waiting for Tx buffer space as a 2*RTT delay is really small over 10G
>      ethernet and a 1 jiffy timeout might be essentially 0 if at the end of
>      the jiffy period.
> 
>  (4) Fix some tracing output in AFS to make it consistent with rxrpc.
> 
>  (5) Make sure aborted asynchronous AFS operations are tidied up properly
>      so we don't end up with stuck rxrpc calls.
> 
>  (6) Make AFS client calls uninterruptible in the Rx phase.  If we don't
>      wait for the reply to be fully gathered, we can't update the local VFS
>      state and we end up in an indeterminate state with respect to the
>      server.
> 
> The patches are tagged here:
> 
> 	git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs.git
> 	rxrpc-fixes-20200319

Pulled, thanks David.