OS-881 To workaround OS-580 add support to only invalidate mappings from a single process

@@ -19,10 +19,11 @@
  * CDDL HEADER END
  */
 /*
  * Copyright (c) 1986, 2010, Oracle and/or its affiliates. All rights reserved.
  * Copyright 2015 Nexenta Systems, Inc.  All rights reserved.
+ * Copyright (c) 2012, Joyent, Inc. All rights reserved.
  */
 
 /*      Copyright (c) 1984, 1986, 1987, 1988, 1989 AT&T */
 /*        All Rights Reserved   */
 

@@ -430,12 +431,19 @@
                         } else {
                                 hat_setmod_only(pp);
                                 page_io_unlock(pp);
                                 page_unlock(pp);
                         }
-                } else if (flags & B_INVAL) {
+                } else if ((flags & (B_INVAL | B_INVALCURONLY)) == B_INVAL) {
                         /*
+                         * If B_INVALCURONLY is set, then we handle that case
+                         * in the next conditional if hat_page_is_mapped()
+                         * indicates that there are no additional mappings
+                         * to the page.
+                         */
+
+                        /*
                          * XXX - Failed writes with B_INVAL set are
                          * not handled appropriately.
                          */
                         page_io_unlock(pp);
                         /*LINTED: constant in conditional context*/

@@ -571,12 +579,13 @@
             tnf_ulong,  pages_freed,            dfree,
             tnf_ulong,  pages_reclaimed,        pgrec);
 }
 
 /*
- * Flags are composed of {B_ASYNC, B_INVAL, B_FREE, B_DONTNEED, B_DELWRI,
- * B_TRUNC, B_FORCE}.  B_DELWRI indicates that this page is part of a kluster
+ * Flags are composed of {B_ASYNC, B_INVAL, B_INVALCURONLY, B_FREE,
+ * B_DONTNEED, B_DELWRI, B_TRUNC, B_FORCE}.
+ * B_DELWRI indicates that this page is part of a kluster
  * operation and is only to be considered if it doesn't involve any
  * waiting here.  B_TRUNC indicates that the file is being truncated
  * and so no i/o needs to be done. B_FORCE indicates that the page
  * must be destroyed so don't try wrting it out.
  *

@@ -626,17 +635,21 @@
 
         /*
          * If we want to free or invalidate the page then
          * we need to unload it so that anyone who wants
          * it will have to take a minor fault to get it.
+         * If we are only invalidating the page for the
+         * current process, then pass in a different flag.
          * Otherwise, we're just writing the page back so we
          * need to sync up the hardwre and software mod bit to
          * detect any future modifications.  We clear the
          * software mod bit when we put the page on the dirty
          * list.
          */
-        if (flags & (B_INVAL | B_FREE)) {
+        if (flags & B_INVALCURONLY) {
+                (void) hat_pageunload(pp, HAT_CURPROC_PGUNLOAD);
+        } else if (flags & (B_INVAL | B_FREE)) {
                 (void) hat_pageunload(pp, HAT_FORCE_PGUNLOAD);
         } else {
                 (void) hat_pagesync(pp, HAT_SYNC_ZERORM);
         }
 

@@ -644,11 +657,11 @@
                 /*
                  * Don't need to add it to the
                  * list after all.
                  */
                 page_io_unlock(pp);
-                if (flags & B_INVAL) {
+                if ((flags & (B_INVAL | B_INVALCURONLY)) == B_INVAL) {
                         /*LINTED: constant in conditional context*/
                         VN_DISPOSE(pp, B_INVAL, 0, kcred);
                 } else if (flags & B_FREE) {
                         /*LINTED: constant in conditional context*/
                         VN_DISPOSE(pp, B_FREE, (flags & B_DONTNEED), kcred);

@@ -656,10 +669,13 @@
                         /*
                          * This is advisory path for the callers
                          * of VOP_PUTPAGE() who prefer freeing the
                          * page _only_ if no one else is accessing it.
                          * E.g. segmap_release()
+                         * We also take this path for B_INVALCURONLY and
+                         * let page_release call VN_DISPOSE if no one else is
+                         * using the page.
                          *
                          * The above hat_ismod() check is useless because:
                          * (1) we may not be holding SE_EXCL lock;
                          * (2) we've not unloaded _all_ translations
                          *

@@ -680,11 +696,11 @@
          * If we're going to free the page when we're done
          * then we can let others try to use it starting now.
          * We'll detect the fact that they used it when the
          * i/o is done and avoid freeing the page.
          */
-        if (flags & B_FREE)
+        if (flags & (B_FREE | B_INVALCURONLY))
                 page_downgrade(pp);
 
 
         TRACE_1(TR_FAC_VM, TR_PVN_GETDIRTY, "pvn_getdirty:pp %p", pp);