Atomically collect callbacks to be broken

Collect callbacks to be broken in one go, otherwise a file server may
lock out a client while new callbacks tickle in.

With revised multi_Rx, responses get handled early, taking away an argument for
issuing callbacks in small chunks -> crank up chunk size.

Change-Id: I6822256715d1388aa1a44049315813ea08009105
Reviewed-on: http://gerrit.openafs.org/3909
Reviewed-by: Derrick Brashear <shadow@dementia.org>
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Jeffrey Altman <jaltman@openafs.org>

diff --git a/src/viced/callback.c b/src/viced/callback.c
index 073d563..13b5cf1 100644 (file)
--- a/src/viced/callback.c
+++ b/src/viced/callback.c
@@ -799,8 +799,8 @@ BreakCallBack(struct host *xhost, AFSFid * fid, int flag)
 {
     struct FileEntry *fe;
     struct CallBack *cb, *nextcb;
-    struct cbstruct cba[MAX_CB_HOSTS];
-    int ncbas;
+    struct cbstruct cbaDef[MAX_CB_HOSTS], *cba = cbaDef;
+    unsigned int ncbas, cbaAlloc = MAX_CB_HOSTS;
     struct AFSCBFids tf;
     int hostindex;
     char hoststr[16];
@@ -825,8 +825,7 @@ BreakCallBack(struct host *xhost, AFSFid * fid, int flag)
     tf.AFSCBFids_len = 1;
     tf.AFSCBFids_val = fid;
 
-    for (; cb;) {
-       for (ncbas = 0; cb && ncbas < MAX_CB_HOSTS; cb = nextcb) {
+       for (ncbas = 0; cb ; cb = nextcb) {
            nextcb = itocb(cb->cnext);
            if ((cb->hhead != hostindex || flag)
                && (cb->status == CB_BULK || cb->status == CB_NORMAL
@@ -843,6 +842,21 @@ BreakCallBack(struct host *xhost, AFSFid * fid, int flag)
                } else {
                    if (!(thishost->hostFlags & HOSTDELETED)) {
                        h_Hold_r(thishost);
+                       if (ncbas == cbaAlloc) {        /* Need more space */
+                           int curLen = cbaAlloc*sizeof(cba[0]);
+                           struct cbstruct *cbaOld = (cba == cbaDef) ? NULL : cba;
+
+                           /* There are logical contraints elsewhere that the number of hosts
+                              (i.e. h_HTSPERBLOCK*h_MAXHOSTTABLES) remains in the realm of a signed "int".
+                              cbaAlloc is defined unsigned int hence doubling below cannot overflow
+                           */
+                           cbaAlloc = cbaAlloc<<1;     /* double */
+                           cba = realloc(cbaOld, cbaAlloc * sizeof(cba[0]));
+
+                           if (cbaOld == NULL) {       /* realloc wouldn't have copied from cbaDef */
+                               memcpy(cba, cbaDef, curLen);
+                           }
+                       }
                        cba[ncbas].hp = thishost;
                        cba[ncbas].thead = cb->thead;
                        ncbas++;
@@ -856,20 +870,16 @@ BreakCallBack(struct host *xhost, AFSFid * fid, int flag)
        }
 
        if (ncbas) {
-           MultiBreakCallBack_r(cba, ncbas, &tf, xhost);
+           struct cbstruct *cba2;
+           int num;
 
-           /* we need to to all these initializations again because MultiBreakCallBack may block */
-           fe = FindFE(fid);
-           if (!fe) {
-               goto done;
-           }
-           cb = itocb(fe->firstcb);
-           if (!cb || ((fe->ncbs == 1) && (cb->hhead == hostindex) && !flag)) {
-               /* the most common case is what follows the || */
-               goto done;
+           for (cba2 = cba, num = ncbas; ncbas > 0; cba2 += num, ncbas -= num) {
+               num = (ncbas > MAX_CB_HOSTS) ? MAX_CB_HOSTS : ncbas;
+               MultiBreakCallBack_r(cba2, num, &tf, xhost);
            }
        }
-    }
+
+       if (cba != cbaDef) free(cba);
 
   done:
     H_UNLOCK;

diff --git a/src/viced/callback.h b/src/viced/callback.h
index 5359de4..58e6ee0 100644 (file)
--- a/src/viced/callback.h
+++ b/src/viced/callback.h
@@ -19,7 +19,8 @@
  * thereby swamping the file server.  As a result, something like
  * 10 or 15 might be a better bet.
  */
-#define MAX_CB_HOSTS   10
+/* With revised multi_Rx, responses get handled as early as they tickle in, so try big */
+#define MAX_CB_HOSTS   1024
 
 /* max time to break a callback, otherwise client is dead or net is hosed */
 #define MAXCBT 25