afs: support the CB.ProbeUuid RPC op

Add support for the CB.ProbeUuid cache manager RPC op.  This allows a modern
OpenAFS server to quickly ask if the client has been rebooted.

Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2 files changed, 108 insertions, 0 deletions

diff --git a/fs/afs/afs_cm.h b/fs/afs/afs_cm.h
index 5f62f3ea563e..255f5dd6040c 100644
--- a/fs/afs/afs_cm.h
+++ b/fs/afs/afs_cm.h
@@ -24,6 +24,7 @@ enum AFS_CM_Operations {
         CBGetXStatsVersion      = 209,  /* get version of extended statistics */
         CBGetXStats             = 210,  /* get contents of extended statistics data */
         CBInitCallBackState3    = 213,  /* initialise callback state, version 3 */
+        CBProbeUuid             = 214,  /* check the client hasn't rebooted */
         CBTellMeAboutYourself   = 65538, /* get client capabilities */
 };
 
diff --git a/fs/afs/cmservice.c b/fs/afs/cmservice.c
index 75da3d04612c..eb765489164f 100644
--- a/fs/afs/cmservice.c
+++ b/fs/afs/cmservice.c
@@ -26,6 +26,7 @@ static int afs_deliver_cb_init_call_back_state3(struct afs_call *,
                                                 struct sk_buff *, bool);
 static int afs_deliver_cb_probe(struct afs_call *, struct sk_buff *, bool);
 static int afs_deliver_cb_callback(struct afs_call *, struct sk_buff *, bool);
+static int afs_deliver_cb_probe_uuid(struct afs_call *, struct sk_buff *, bool);
 static int afs_deliver_cb_tell_me_about_yourself(struct afs_call *,
                                                  struct sk_buff *, bool);
 static void afs_cm_destructor(struct afs_call *);
@@ -71,6 +72,16 @@ static const struct afs_call_type afs_SRXCBProbe = {
 };
 
 /*
+ * CB.ProbeUuid operation type
+ */
+static const struct afs_call_type afs_SRXCBProbeUuid = {
+        .name           = "CB.ProbeUuid",
+        .deliver        = afs_deliver_cb_probe_uuid,
+        .abort_to_error = afs_abort_to_error,
+        .destructor     = afs_cm_destructor,
+};
+
+/*
  * CB.TellMeAboutYourself operation type
  */
 static const struct afs_call_type afs_SRXCBTellMeAboutYourself = {
@@ -393,6 +404,102 @@ static int afs_deliver_cb_probe(struct afs_call *call, struct sk_buff *skb,
 }
 
 /*
+ * allow the fileserver to quickly find out if the fileserver has been rebooted
+ */
+static void SRXAFSCB_ProbeUuid(struct work_struct *work)
+{
+        struct afs_call *call = container_of(work, struct afs_call, work);
+        struct afs_uuid *r = call->request;
+
+        struct {
+                __be32  match;
+        } reply;
+
+        _enter("");
+
+
+        if (memcmp(r, &afs_uuid, sizeof(afs_uuid)) == 0)
+                reply.match = htonl(0);
+        else
+                reply.match = htonl(1);
+
+        afs_send_simple_reply(call, &reply, sizeof(reply));
+        _leave("");
+}
+
+/*
+ * deliver request data to a CB.ProbeUuid call
+ */
+static int afs_deliver_cb_probe_uuid(struct afs_call *call, struct sk_buff *skb,
+                                     bool last)
+{
+        struct afs_uuid *r;
+        unsigned loop;
+        __be32 *b;
+        int ret;
+
+        _enter("{%u},{%u},%d", call->unmarshall, skb->len, last);
+
+        if (skb->len > 0)
+                return -EBADMSG;
+        if (!last)
+                return 0;
+
+        switch (call->unmarshall) {
+        case 0:
+                call->offset = 0;
+                call->buffer = kmalloc(11 * sizeof(__be32), GFP_KERNEL);
+                if (!call->buffer)
+                        return -ENOMEM;
+                call->unmarshall++;
+
+        case 1:
+                _debug("extract UUID");
+                ret = afs_extract_data(call, skb, last, call->buffer,
+                                       11 * sizeof(__be32));
+                switch (ret) {
+                case 0:         break;
+                case -EAGAIN:   return 0;
+                default:        return ret;
+                }
+
+                _debug("unmarshall UUID");
+                call->request = kmalloc(sizeof(struct afs_uuid), GFP_KERNEL);
+                if (!call->request)
+                        return -ENOMEM;
+
+                b = call->buffer;
+                r = call->request;
+                r->time_low                     = ntohl(b[0]);
+                r->time_mid                     = ntohl(b[1]);
+                r->time_hi_and_version          = ntohl(b[2]);
+                r->clock_seq_hi_and_reserved    = ntohl(b[3]);
+                r->clock_seq_low                = ntohl(b[4]);
+
+                for (loop = 0; loop < 6; loop++)
+                        r->node[loop] = ntohl(b[loop + 5]);
+
+                call->offset = 0;
+                call->unmarshall++;
+
+        case 2:
+                _debug("trailer");
+                if (skb->len != 0)
+                        return -EBADMSG;
+                break;
+        }
+
+        if (!last)
+                return 0;
+
+        call->state = AFS_CALL_REPLYING;
+
+        INIT_WORK(&call->work, SRXAFSCB_ProbeUuid);
+        schedule_work(&call->work);
+        return 0;
+}
+
+/*
  * allow the fileserver to ask about the cache manager's capabilities
  */
 static void SRXAFSCB_TellMeAboutYourself(struct work_struct *work)