diff options
| -rw-r--r-- | defpager/backing.c | 131 | ||||
| -rw-r--r-- | defpager/defpager.c | 145 |
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) +{ +} |