CRED: Wrap task credential accesses in the JFS filesystem
[linux-2.6.git] / drivers / video / fb_defio.c
1 /*
2  *  linux/drivers/video/fb_defio.c
3  *
4  *  Copyright (C) 2006 Jaya Kumar
5  *
6  * This file is subject to the terms and conditions of the GNU General Public
7  * License. See the file COPYING in the main directory of this archive
8  * for more details.
9  */
10
11 #include <linux/module.h>
12 #include <linux/kernel.h>
13 #include <linux/errno.h>
14 #include <linux/string.h>
15 #include <linux/mm.h>
16 #include <linux/slab.h>
17 #include <linux/vmalloc.h>
18 #include <linux/delay.h>
19 #include <linux/interrupt.h>
20 #include <linux/fb.h>
21 #include <linux/list.h>
22
23 /* to support deferred IO */
24 #include <linux/rmap.h>
25 #include <linux/pagemap.h>
26
27 /* this is to find and return the vmalloc-ed fb pages */
28 static int fb_deferred_io_fault(struct vm_area_struct *vma,
29                                 struct vm_fault *vmf)
30 {
31         unsigned long offset;
32         struct page *page;
33         struct fb_info *info = vma->vm_private_data;
34         /* info->screen_base is virtual memory */
35         void *screen_base = (void __force *) info->screen_base;
36
37         offset = vmf->pgoff << PAGE_SHIFT;
38         if (offset >= info->fix.smem_len)
39                 return VM_FAULT_SIGBUS;
40
41         page = vmalloc_to_page(screen_base + offset);
42         if (!page)
43                 return VM_FAULT_SIGBUS;
44
45         get_page(page);
46
47         if (vma->vm_file)
48                 page->mapping = vma->vm_file->f_mapping;
49         else
50                 printk(KERN_ERR "no mapping available\n");
51
52         BUG_ON(!page->mapping);
53         page->index = vmf->pgoff;
54
55         vmf->page = page;
56         return 0;
57 }
58
59 int fb_deferred_io_fsync(struct file *file, struct dentry *dentry, int datasync)
60 {
61         struct fb_info *info = file->private_data;
62
63         /* Kill off the delayed work */
64         cancel_rearming_delayed_work(&info->deferred_work);
65
66         /* Run it immediately */
67         return schedule_delayed_work(&info->deferred_work, 0);
68 }
69 EXPORT_SYMBOL_GPL(fb_deferred_io_fsync);
70
71 /* vm_ops->page_mkwrite handler */
72 static int fb_deferred_io_mkwrite(struct vm_area_struct *vma,
73                                   struct page *page)
74 {
75         struct fb_info *info = vma->vm_private_data;
76         struct fb_deferred_io *fbdefio = info->fbdefio;
77         struct page *cur;
78
79         /* this is a callback we get when userspace first tries to
80         write to the page. we schedule a workqueue. that workqueue
81         will eventually mkclean the touched pages and execute the
82         deferred framebuffer IO. then if userspace touches a page
83         again, we repeat the same scheme */
84
85         /* protect against the workqueue changing the page list */
86         mutex_lock(&fbdefio->lock);
87
88         /* we loop through the pagelist before adding in order
89         to keep the pagelist sorted */
90         list_for_each_entry(cur, &fbdefio->pagelist, lru) {
91                 /* this check is to catch the case where a new
92                 process could start writing to the same page
93                 through a new pte. this new access can cause the
94                 mkwrite even when the original ps's pte is marked
95                 writable */
96                 if (unlikely(cur == page))
97                         goto page_already_added;
98                 else if (cur->index > page->index)
99                         break;
100         }
101
102         list_add_tail(&page->lru, &cur->lru);
103
104 page_already_added:
105         mutex_unlock(&fbdefio->lock);
106
107         /* come back after delay to process the deferred IO */
108         schedule_delayed_work(&info->deferred_work, fbdefio->delay);
109         return 0;
110 }
111
112 static struct vm_operations_struct fb_deferred_io_vm_ops = {
113         .fault          = fb_deferred_io_fault,
114         .page_mkwrite   = fb_deferred_io_mkwrite,
115 };
116
117 static int fb_deferred_io_set_page_dirty(struct page *page)
118 {
119         if (!PageDirty(page))
120                 SetPageDirty(page);
121         return 0;
122 }
123
124 static const struct address_space_operations fb_deferred_io_aops = {
125         .set_page_dirty = fb_deferred_io_set_page_dirty,
126 };
127
128 static int fb_deferred_io_mmap(struct fb_info *info, struct vm_area_struct *vma)
129 {
130         vma->vm_ops = &fb_deferred_io_vm_ops;
131         vma->vm_flags |= ( VM_IO | VM_RESERVED | VM_DONTEXPAND );
132         vma->vm_private_data = info;
133         return 0;
134 }
135
136 /* workqueue callback */
137 static void fb_deferred_io_work(struct work_struct *work)
138 {
139         struct fb_info *info = container_of(work, struct fb_info,
140                                                 deferred_work.work);
141         struct list_head *node, *next;
142         struct page *cur;
143         struct fb_deferred_io *fbdefio = info->fbdefio;
144
145         /* here we mkclean the pages, then do all deferred IO */
146         mutex_lock(&fbdefio->lock);
147         list_for_each_entry(cur, &fbdefio->pagelist, lru) {
148                 lock_page(cur);
149                 page_mkclean(cur);
150                 unlock_page(cur);
151         }
152
153         /* driver's callback with pagelist */
154         fbdefio->deferred_io(info, &fbdefio->pagelist);
155
156         /* clear the list */
157         list_for_each_safe(node, next, &fbdefio->pagelist) {
158                 list_del(node);
159         }
160         mutex_unlock(&fbdefio->lock);
161 }
162
163 void fb_deferred_io_init(struct fb_info *info)
164 {
165         struct fb_deferred_io *fbdefio = info->fbdefio;
166
167         BUG_ON(!fbdefio);
168         mutex_init(&fbdefio->lock);
169         info->fbops->fb_mmap = fb_deferred_io_mmap;
170         INIT_DELAYED_WORK(&info->deferred_work, fb_deferred_io_work);
171         INIT_LIST_HEAD(&fbdefio->pagelist);
172         if (fbdefio->delay == 0) /* set a default of 1 s */
173                 fbdefio->delay = HZ;
174 }
175 EXPORT_SYMBOL_GPL(fb_deferred_io_init);
176
177 void fb_deferred_io_open(struct fb_info *info,
178                          struct inode *inode,
179                          struct file *file)
180 {
181         file->f_mapping->a_ops = &fb_deferred_io_aops;
182 }
183 EXPORT_SYMBOL_GPL(fb_deferred_io_open);
184
185 void fb_deferred_io_cleanup(struct fb_info *info)
186 {
187         void *screen_base = (void __force *) info->screen_base;
188         struct fb_deferred_io *fbdefio = info->fbdefio;
189         struct page *page;
190         int i;
191
192         BUG_ON(!fbdefio);
193         cancel_delayed_work(&info->deferred_work);
194         flush_scheduled_work();
195
196         /* clear out the mapping that we setup */
197         for (i = 0 ; i < info->fix.smem_len; i += PAGE_SIZE) {
198                 page = vmalloc_to_page(screen_base + i);
199                 page->mapping = NULL;
200         }
201 }
202 EXPORT_SYMBOL_GPL(fb_deferred_io_cleanup);
203
204 MODULE_LICENSE("GPL");