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/vmalloc.h> 17 #include <linux/delay.h> 18 #include <linux/interrupt.h> 19 #include <linux/fb.h> 20 #include <linux/list.h> 21 22 /* to support deferred IO */ 23 #include <linux/rmap.h> 24 #include <linux/pagemap.h> 25 26 static struct page *fb_deferred_io_page(struct fb_info *info, unsigned long offs) 27 { 28 void *screen_base = (void __force *) info->screen_base; 29 struct page *page; 30 31 if (is_vmalloc_addr(screen_base + offs)) 32 page = vmalloc_to_page(screen_base + offs); 33 else 34 page = pfn_to_page((info->fix.smem_start + offs) >> PAGE_SHIFT); 35 36 return page; 37 } 38 39 /* this is to find and return the vmalloc-ed fb pages */ 40 static int fb_deferred_io_fault(struct vm_area_struct *vma, 41 struct vm_fault *vmf) 42 { 43 unsigned long offset; 44 struct page *page; 45 struct fb_info *info = vma->vm_private_data; 46 47 offset = vmf->pgoff << PAGE_SHIFT; 48 if (offset >= info->fix.smem_len) 49 return VM_FAULT_SIGBUS; 50 51 page = fb_deferred_io_page(info, offset); 52 if (!page) 53 return VM_FAULT_SIGBUS; 54 55 get_page(page); 56 57 if (vma->vm_file) 58 page->mapping = vma->vm_file->f_mapping; 59 else 60 printk(KERN_ERR "no mapping available\n"); 61 62 BUG_ON(!page->mapping); 63 page->index = vmf->pgoff; 64 65 vmf->page = page; 66 return 0; 67 } 68 69 int fb_deferred_io_fsync(struct file *file, loff_t start, loff_t end, int datasync) 70 { 71 struct fb_info *info = file->private_data; 72 struct inode *inode = file_inode(file); 73 int err = filemap_write_and_wait_range(inode->i_mapping, start, end); 74 if (err) 75 return err; 76 77 /* Skip if deferred io is compiled-in but disabled on this fbdev */ 78 if (!info->fbdefio) 79 return 0; 80 81 mutex_lock(&inode->i_mutex); 82 /* Kill off the delayed work */ 83 cancel_delayed_work_sync(&info->deferred_work); 84 85 /* Run it immediately */ 86 err = schedule_delayed_work(&info->deferred_work, 0); 87 mutex_unlock(&inode->i_mutex); 88 return err; 89 } 90 EXPORT_SYMBOL_GPL(fb_deferred_io_fsync); 91 92 /* vm_ops->page_mkwrite handler */ 93 static int fb_deferred_io_mkwrite(struct vm_area_struct *vma, 94 struct vm_fault *vmf) 95 { 96 struct page *page = vmf->page; 97 struct fb_info *info = vma->vm_private_data; 98 struct fb_deferred_io *fbdefio = info->fbdefio; 99 struct page *cur; 100 101 /* this is a callback we get when userspace first tries to 102 write to the page. we schedule a workqueue. that workqueue 103 will eventually mkclean the touched pages and execute the 104 deferred framebuffer IO. then if userspace touches a page 105 again, we repeat the same scheme */ 106 107 file_update_time(vma->vm_file); 108 109 /* protect against the workqueue changing the page list */ 110 mutex_lock(&fbdefio->lock); 111 112 /* first write in this cycle, notify the driver */ 113 if (fbdefio->first_io && list_empty(&fbdefio->pagelist)) 114 fbdefio->first_io(info); 115 116 /* 117 * We want the page to remain locked from ->page_mkwrite until 118 * the PTE is marked dirty to avoid page_mkclean() being called 119 * before the PTE is updated, which would leave the page ignored 120 * by defio. 121 * Do this by locking the page here and informing the caller 122 * about it with VM_FAULT_LOCKED. 123 */ 124 lock_page(page); 125 126 /* we loop through the pagelist before adding in order 127 to keep the pagelist sorted */ 128 list_for_each_entry(cur, &fbdefio->pagelist, lru) { 129 /* this check is to catch the case where a new 130 process could start writing to the same page 131 through a new pte. this new access can cause the 132 mkwrite even when the original ps's pte is marked 133 writable */ 134 if (unlikely(cur == page)) 135 goto page_already_added; 136 else if (cur->index > page->index) 137 break; 138 } 139 140 list_add_tail(&page->lru, &cur->lru); 141 142 page_already_added: 143 mutex_unlock(&fbdefio->lock); 144 145 /* come back after delay to process the deferred IO */ 146 schedule_delayed_work(&info->deferred_work, fbdefio->delay); 147 return VM_FAULT_LOCKED; 148 } 149 150 static const struct vm_operations_struct fb_deferred_io_vm_ops = { 151 .fault = fb_deferred_io_fault, 152 .page_mkwrite = fb_deferred_io_mkwrite, 153 }; 154 155 static int fb_deferred_io_set_page_dirty(struct page *page) 156 { 157 if (!PageDirty(page)) 158 SetPageDirty(page); 159 return 0; 160 } 161 162 static const struct address_space_operations fb_deferred_io_aops = { 163 .set_page_dirty = fb_deferred_io_set_page_dirty, 164 }; 165 166 static int fb_deferred_io_mmap(struct fb_info *info, struct vm_area_struct *vma) 167 { 168 vma->vm_ops = &fb_deferred_io_vm_ops; 169 vma->vm_flags |= VM_DONTEXPAND | VM_DONTDUMP; 170 if (!(info->flags & FBINFO_VIRTFB)) 171 vma->vm_flags |= VM_IO; 172 vma->vm_private_data = info; 173 return 0; 174 } 175 176 /* workqueue callback */ 177 static void fb_deferred_io_work(struct work_struct *work) 178 { 179 struct fb_info *info = container_of(work, struct fb_info, 180 deferred_work.work); 181 struct list_head *node, *next; 182 struct page *cur; 183 struct fb_deferred_io *fbdefio = info->fbdefio; 184 185 /* here we mkclean the pages, then do all deferred IO */ 186 mutex_lock(&fbdefio->lock); 187 list_for_each_entry(cur, &fbdefio->pagelist, lru) { 188 lock_page(cur); 189 page_mkclean(cur); 190 unlock_page(cur); 191 } 192 193 /* driver's callback with pagelist */ 194 fbdefio->deferred_io(info, &fbdefio->pagelist); 195 196 /* clear the list */ 197 list_for_each_safe(node, next, &fbdefio->pagelist) { 198 list_del(node); 199 } 200 mutex_unlock(&fbdefio->lock); 201 } 202 203 void fb_deferred_io_init(struct fb_info *info) 204 { 205 struct fb_deferred_io *fbdefio = info->fbdefio; 206 207 BUG_ON(!fbdefio); 208 mutex_init(&fbdefio->lock); 209 info->fbops->fb_mmap = fb_deferred_io_mmap; 210 INIT_DELAYED_WORK(&info->deferred_work, fb_deferred_io_work); 211 INIT_LIST_HEAD(&fbdefio->pagelist); 212 if (fbdefio->delay == 0) /* set a default of 1 s */ 213 fbdefio->delay = HZ; 214 } 215 EXPORT_SYMBOL_GPL(fb_deferred_io_init); 216 217 void fb_deferred_io_open(struct fb_info *info, 218 struct inode *inode, 219 struct file *file) 220 { 221 file->f_mapping->a_ops = &fb_deferred_io_aops; 222 } 223 EXPORT_SYMBOL_GPL(fb_deferred_io_open); 224 225 void fb_deferred_io_cleanup(struct fb_info *info) 226 { 227 struct fb_deferred_io *fbdefio = info->fbdefio; 228 struct page *page; 229 int i; 230 231 BUG_ON(!fbdefio); 232 cancel_delayed_work_sync(&info->deferred_work); 233 234 /* clear out the mapping that we setup */ 235 for (i = 0 ; i < info->fix.smem_len; i += PAGE_SIZE) { 236 page = fb_deferred_io_page(info, i); 237 page->mapping = NULL; 238 } 239 240 info->fbops->fb_mmap = NULL; 241 mutex_destroy(&fbdefio->lock); 242 } 243 EXPORT_SYMBOL_GPL(fb_deferred_io_cleanup); 244 245 MODULE_LICENSE("GPL"); 246