sys/dev/drm/linux_shmem.c

   1 /*-
   2  * Copyright (c) 2011 The FreeBSD Foundation
   3  * Copyright (c) 2014 François Tigeot
   4  * All rights reserved.
   5  *
   6  * Portions of this software were developed by Konstantin Belousov
   7  * under sponsorship from the FreeBSD Foundation.
   8  *
   9  * Redistribution and use in source and binary forms, with or without
  10  * modification, are permitted provided that the following conditions
  11  * are met:
  12  * 1. Redistributions of source code must retain the above copyright
  13  *    notice, this list of conditions and the following disclaimer.
  14  * 2. Redistributions in binary form must reproduce the above copyright
  15  *    notice, this list of conditions and the following disclaimer in the
  16  *    documentation and/or other materials provided with the distribution.
  17  *
  18  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  19  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  20  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  21  * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  22  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  23  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  24  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  25  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  26  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  27  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  28  * SUCH DAMAGE.
  29  *
  30  */
  31
  32 #include <vm/vm.h>
  33 #include <vm/vm_page.h>
  34 #include <vm/vm_page2.h>
  35 #include <vm/vm_pager.h>
  36
  37 #include <linux/err.h>
  38 #include <linux/shmem_fs.h>
  39
  40 struct page *
  41 shmem_read_mapping_page(vm_object_t object, vm_pindex_t pindex)
  42 {
  43         vm_page_t m;
  44         int rv;
  45
  46         VM_OBJECT_LOCK_ASSERT_OWNED(object);
  47         m = vm_page_grab(object, pindex, VM_ALLOC_NORMAL | VM_ALLOC_RETRY);
  48         if (m->valid != VM_PAGE_BITS_ALL) {
  49                 if (vm_pager_has_page(object, pindex)) {
  50                         rv = vm_pager_get_page(object, &m, 1);
  51                         m = vm_page_lookup(object, pindex);
  52                         if (m == NULL)
  53                                 return ERR_PTR(-ENOMEM);
  54                         if (rv != VM_PAGER_OK) {
  55                                 vm_page_free(m);
  56                                 return ERR_PTR(-ENOMEM);
  57                         }
  58                 } else {
  59                         pmap_zero_page(VM_PAGE_TO_PHYS(m));
  60                         m->valid = VM_PAGE_BITS_ALL;
  61                         m->dirty = 0;
  62                 }
  63         }
  64         vm_page_wire(m);
  65         vm_page_wakeup(m);
  66         return (struct page *)m;
  67 }