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-rw-r--r--defpager/backing.c131
-rw-r--r--defpager/defpager.c145
2 files changed, 249 insertions, 27 deletions
diff --git a/defpager/backing.c b/defpager/backing.c
new file mode 100644
index 00000000..5e6fbb65
--- /dev/null
+++ b/defpager/backing.c
@@ -0,0 +1,131 @@
+/* Backing store management for GNU Hurd.
+ Copyright (C) 1996 Free Software Foundation, Inc.
+ Written by Thomas Bushnell, n/BSG.
+
+ This file is part of the GNU Hurd.
+
+ The GNU Hurd is free software; you can redistribute it and/or
+ modify it under the terms of the GNU General Public License as
+ published by the Free Software Foundation; either version 2, or (at
+ your option) any later version.
+
+ The GNU Hurd is distributed in the hope that it will be useful, but
+ WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with this program; if not, write to the Free Software
+ Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */
+
+
+#include <hurd/store.h>
+
+const struct store_class *const permitted_classes[] =
+{
+ &store_device_class, &store_ileave_class, &store_concat_class, 0
+};
+
+/* Allocation map, by PAGE. */
+/* If a bit is SET the corresponding PAGE is free. */
+char *bmap;
+
+/* Number of bytes in bmap */
+size_t bmap_len;
+
+/* Allocation rotor */
+char *bmap_rotor;
+
+struct mutex bmap_lock;
+
+error_t
+init_backing (char *name)
+{
+ error_t err;
+ int i;
+
+ err = store_open (name, STORE_NO_FILEIO, &permitted_classes, &backing_store);
+ if (err)
+ return err;
+
+ bmap_len = backing_store->size / vm_page_size / NBBY;
+ bmap = malloc (bmap_len);
+ for (i = 0; i < bmap_len; i++)
+ bmap[i] = 0xff;
+ bmap_rotor = bmap;
+
+ /* Mark the very first page as occupied. This makes sure we never
+ return zero offsets from allocate_backing_page (which
+ conventionally means that there is no space left. It also makes
+ sure we don't tromp on the misfeature in Linux of using the first
+ page for permanent data. */
+ *bmap_rotor |= 1;
+}
+
+int
+allocate_backing_page ()
+{
+ int wrapped;
+ int bit;
+ int pfn;
+
+ mutex_lock (&bmap_lock);
+
+ wrapped = (bmap_rotor == bmap);
+
+ while (!wrapped || bmap_rotor < bmap + bmap_len)
+ {
+ if (bmap[bmap_rotor])
+ break;
+ bmap_rotor++;
+ if (bmap_rotor >= bmap + bmap_len)
+ wrapped++;
+ }
+
+ if (wrapped == 2)
+ {
+ /* Didn't find one... */
+ mutex_unlock (&bmap_lock);
+ printf ("WARNING: Out of paging space; pageout failing.");
+ return 0;
+ }
+
+ /* Find which bit */
+ bit = ffs (*bmap_rotor);
+ assert (bit);
+ bit--;
+
+ /* Mark it */
+ *bmap_rotor |= 1 << bit;
+
+ /* Return the correct offset */
+ pfn = (bmap_rotor - bmap) * 8 + bit;
+
+ mutex_unlock (&bmap_lock);
+
+ return pfn * (vm_page_size / store->block_size);
+}
+
+
+void
+return_backing_pages (off_t *map, int maplen)
+{
+ int i;
+
+ mutex_lock (&bmap_lock);
+ for (i = 0; i < maplen; i++)
+ {
+ int pfn;
+ char *b;
+ int bit;
+
+ pfn = map[i] / (vm_page_size / store->block_size);
+ b = bmap + pfn & ~7;
+ bit = pfn & 7;
+
+ assert ((*b & (1 << bit)) == 0);
+ *b |= 1 << bit;
+ }
+ mutex_unlock (&bmap_lock);
+}
+
diff --git a/defpager/defpager.c b/defpager/defpager.c
index 60ca6c19..9b0bce3a 100644
--- a/defpager/defpager.c
+++ b/defpager/defpager.c
@@ -1,6 +1,6 @@
/* Default pager for GNU Hurd.
- Copyright (C) 1994 Free Software Foundation, Inc.
- Written by Michael I. Bushnell.
+ Copyright (C) 1996 Free Software Foundation, Inc.
+ Written by Thomas Bushnell, n/BSG.
This file is part of the GNU Hurd.
@@ -18,30 +18,121 @@
along with this program; if not, write to the Free Software
Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */
-/*
- * Mach Operating System
- * Copyright (c) 1993-1989 Carnegie Mellon University
- * All Rights Reserved.
- *
- * Permission to use, copy, modify and distribute this software and its
- * documentation is hereby granted, provided that both the copyright
- * notice and this permission notice appear in all copies of the
- * software, derivative works or modified versions, and any portions
- * thereof, and that both notices appear in supporting documentation.
- *
- * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
- * CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
- * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
- *
- * Carnegie Mellon requests users of this software to return to
- *
- * Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU
- * School of Computer Science
- * Carnegie Mellon University
- * Pittsburgh PA 15213-3890
- *
- * any improvements or extensions that they make and grant Carnegie Mellon
- * the rights to redistribute these changes.
- */
+#include <hurd/pager.h>
+#include <hurd/store.h>
+struct user_pager_info
+{
+ /* Size of the object */
+ vm_size_t size;
+
+ /* One entry for each page of the object. */
+ off_t *map;
+};
+
+
+/* Expand the P->map as necessary to handle an incoming request of the
+ page at ADDR. */
+static inline void
+expand_map (struct user_pager_info *p, vm_offset_t addr)
+{
+ /* See if this is beyond the current extent */
+ if (page >= pager->size)
+ {
+ off_t *newmap;
+ vm_size_t newsize;
+
+ newsize = page + vm_page_size;
+ newmap = realloc (pager->map, size / vm_page_size * sizeof (off_t));
+
+ bzero (pager->map + pager->size / vm_page_size * sizeof (off_t),
+ (newsize - pager->size) / vm_page_size * sizeof (off_t));
+ pager->size = newsize;
+ pager->map = newmap;
+ }
+}
+
+
+error_t
+pager_read_page (struct user_pager_info *pager,
+ vm_offset_t page,
+ vm_address_t *buf,
+ int *write_lock)
+{
+ int pfn = page / vm_page_size;
+ size_t nread;
+
+ /* We never request write locks. */
+ *write_lock = 0;
+
+ expand_map (pager, page);
+
+ if (!pager->map[pfn])
+ vm_allocate (mach_task_self (), buf, vm_page_size, 1);
+ else
+ {
+ store_read (backing_store, pager->map[pfn], vm_page_size,
+ (void **)buf, &nread);
+ if (nread != vm_page_size)
+ {
+ vm_deallocate (mach_task_self (), *buf, nread);
+ return EIO;
+ }
+ }
+ return 0;
+}
+
+
+error_t
+pager_write_page (struct user_pager_info *pager,
+ vm_offset_t page,
+ vm_address_t buf)
+{
+ int pfn = page / vm_page_size;
+ size_t nwritten;
+
+ expand_map (pager, page);
+
+ if (!pager->map[pfn])
+ pager->map[pfn] = allocate_backing_page ();
+
+ /* No more backing store. Oh dear. */
+ if (!pager->map[pfn])
+ return EIO;
+
+ err = store_write (backing_store, pager->map[pfn], (void *) buf,
+ vm_page_size, &nwritten);
+ if (!err && nwritten != vm_page_size)
+ err = EIO;
+ return err;
+}
+
+error_t
+pager_unlock_page (struct user_pager_info *pager,
+ vm_offset_t address)
+{
+ return 0;
+}
+
+error_t
+pager_report_extent (struct user_pager_info *pager,
+ vm_address_t *offset,
+ vm_size_t *size)
+{
+ *offset = 0;
+ *size = pager->size;
+ return 0;
+}
+
+void
+pager_clear_user_data (struct user_pager_info *pager)
+{
+ return_backing_pages (pager->map, pager->size / vm_page_size);
+ free (pager->map);
+}
+
+void
+pager_dropweak (struct user_pager_info *pager)
+{
+}