Formerly data-request.c.~2~

1 files changed, 132 insertions, 1 deletions

diff --git a/libpager/data-request.c b/libpager/data-request.c
index 4280b4e2..5cbfcb7d 100644
--- a/libpager/data-request.c
+++ b/libpager/data-request.c
@@ -1,4 +1,4 @@
-/* Implementation of 
+/* Implementation of memory_object_data_request for pager library
    Copyright (C) 1994 Free Software Foundation
 
    This program is free software; you can redistribute it and/or
@@ -15,3 +15,134 @@
    along with this program; if not, write to the Free Software
    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */
 
+/* Called by the kernel when data is needed upon page fault */
+kern_return_t
+seqnos_memory_object_data_request (mach_port_t object, 
+				   mach_port_seqno_t seqno,
+				   mach_port_t control,
+				   vm_offset_t offset,
+				   vm_size_t length,
+				   vm_prot_t access)
+{
+  struct pager *p;
+  char *pm_entry;
+  int doread, doerror;
+  error_t err;
+  void *page;
+  location_t loc;
+  vm_size_t size, iosize;
+  int write_lock;
+  int extra_zeroes;
+  vm_address_t min, max;
+
+  if (!(p = check_port_type (object, pager_port_type)))
+    return EOPNOTSUPP;
+  
+  /* sanity checks -- we don't do multi-page requests yet.  */
+  if (control != p->memobjcntl)
+    {
+      printf ("incg data request: wrong control port");
+      goto out;
+    }
+  if (length != __vm_page_size)
+    {
+      printf ("incg data request: bad length size");
+      goto out;
+    }
+  if (offset % __vm_page_size)
+    {
+      printf ("incg data request: misaligned request");
+      goto out;
+    }
+
+  /* Acquire the right to meddle with the pagemap */
+  mutex_lock (&p->interlock);
+  _pager_wait_for_seqno (p, seqno);
+
+  _pager_block_termination (p);	/* prevent termination until 
+				   mark_object_error is done */
+
+  if (p->pager_state != NORMAL)
+    {
+      printf ("pager in wrong state for read\n");
+      _pager_release_seqno (p);
+      mutex_unlock (&p->interlock);
+      goto allow_term_out;
+    }
+
+  _pager_pagemap_resize (p, offset + length);
+
+  /* If someone is paging this out right now, the disk contents are
+     unreliable, so we have to wait.  It is too expensive (right now) to
+     find the data and return it, and then interrupt the write, so we just
+     mark the page and have the writing thread do m_o_data_supply when it
+     gets around to it.  */
+  pm_entry = &p->pagemap[offset / __vm_page_size];
+  if (*pm_entry & PM_PAGINGOUT)
+    {
+      doread = 0;
+      *pm_entry |= PM_PAGEINWAIT;
+    }
+  else
+    doread = 1;
+
+  if (*pm_entry & PM_INVALID)
+    doerror = 1;
+  else
+    doerror = 0;
+
+  if (PM_NEXTERROR (*pm_entry) != PAGE_NOERR && (access & VM_PROT_WRITE))
+    {
+      memory_object_data_error (control, offset, length, 
+				page_errors[PM_NEXTERROR (*pm_entry)]);
+      _pager_mark_object_error (p, offset, length, 
+				page_errors[PM_NEXTERROR (*pm_entry)]);
+      *pm_entry = SET_PM_NEXTERROR (*pm_entry, PAGE_NOERR);
+      doread = 0;
+    }
+
+  /* Let someone else in.  */
+  _pager_release_seqno (p);
+  mutex_unlock (&p->interlock);
+
+  if (!doread)
+    goto allow_term_out;
+  if (doerror)
+    goto error_read;
+
+  err = pager_find_address (p->upi, offset, &loc, &size, &iosize, &write_lock);
+
+  if (!err)
+    error = pager_read_page (loc, &page, iosize, &extra_zeroes);
+
+  if (err)
+    goto error_read;
+  
+  if (size != __vm_page_size && !extra_zeroes)
+    bzero (page + size, __vm_page_size - size);
+  
+  memory_object_data_supply (p->memobjcntl, offset, (u_int) page, length, 1,
+			     write_lock ? VM_PROT_WRITE : VM_PROT_NONE, 0,
+			     MACH_PORT_NULL);
+  mutex_lock (&p->interlock);
+  _pager_mark_object_error (p, offset, length, 0);
+  _pager_allow_termination (p);
+  mutex_unlock (&p->interlock);
+  done_with_port (p);
+  return 0;
+
+ allow_term_out:
+  mutex_lock (&p->interlock);
+  _pager_allow_termination (p);
+  mutex_unlock (&p->interlock);
+ out:
+  done_with_port (p);
+  return 0;
+  
+ error_read:
+  memory_object_data_error (p->memobjcntl, offset, length, EIO);
+  _pager_mark_object_error (p, offset, length, EIO);
+  _pager_allow_termination (p);
+  done_with_port (p);
+  return 0;
+}