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 schedule_delayed_work(&info->deferred_work, 0); 87 mutex_unlock(&inode->i_mutex); 88 89 return 0; 90 } 91 EXPORT_SYMBOL_GPL(fb_deferred_io_fsync); 92 93 /* vm_ops->page_mkwrite handler */ 94 static int fb_deferred_io_mkwrite(struct vm_area_struct *vma, 95 struct vm_fault *vmf) 96 { 97 struct page *page = vmf->page; 98 struct fb_info *info = vma->vm_private_data; 99 struct fb_deferred_io *fbdefio = info->fbdefio; 100 struct page *cur; 101 102 /* this is a callback we get when userspace first tries to 103 write to the page. we schedule a workqueue. that workqueue 104 will eventually mkclean the touched pages and execute the 105 deferred framebuffer IO. then if userspace touches a page 106 again, we repeat the same scheme */ 107 108 file_update_time(vma->vm_file); 109 110 /* protect against the workqueue changing the page list */ 111 mutex_lock(&fbdefio->lock); 112 113 /* first write in this cycle, notify the driver */ 114 if (fbdefio->first_io && list_empty(&fbdefio->pagelist)) 115 fbdefio->first_io(info); 116 117 /* 118 * We want the page to remain locked from ->page_mkwrite until 119 * the PTE is marked dirty to avoid page_mkclean() being called 120 * before the PTE is updated, which would leave the page ignored 121 * by defio. 122 * Do this by locking the page here and informing the caller 123 * about it with VM_FAULT_LOCKED. 124 */ 125 lock_page(page); 126 127 /* we loop through the pagelist before adding in order 128 to keep the pagelist sorted */ 129 list_for_each_entry(cur, &fbdefio->pagelist, lru) { 130 /* this check is to catch the case where a new 131 process could start writing to the same page 132 through a new pte. this new access can cause the 133 mkwrite even when the original ps's pte is marked 134 writable */ 135 if (unlikely(cur == page)) 136 goto page_already_added; 137 else if (cur->index > page->index) 138 break; 139 } 140 141 list_add_tail(&page->lru, &cur->lru); 142 143 page_already_added: 144 mutex_unlock(&fbdefio->lock); 145 146 /* come back after delay to process the deferred IO */ 147 schedule_delayed_work(&info->deferred_work, fbdefio->delay); 148 return VM_FAULT_LOCKED; 149 } 150 151 static const struct vm_operations_struct fb_deferred_io_vm_ops = { 152 .fault = fb_deferred_io_fault, 153 .page_mkwrite = fb_deferred_io_mkwrite, 154 }; 155 156 static int fb_deferred_io_set_page_dirty(struct page *page) 157 { 158 if (!PageDirty(page)) 159 SetPageDirty(page); 160 return 0; 161 } 162 163 static const struct address_space_operations fb_deferred_io_aops = { 164 .set_page_dirty = fb_deferred_io_set_page_dirty, 165 }; 166 167 static int fb_deferred_io_mmap(struct fb_info *info, struct vm_area_struct *vma) 168 { 169 vma->vm_ops = &fb_deferred_io_vm_ops; 170 vma->vm_flags |= VM_DONTEXPAND | VM_DONTDUMP; 171 if (!(info->flags & FBINFO_VIRTFB)) 172 vma->vm_flags |= VM_IO; 173 vma->vm_private_data = info; 174 return 0; 175 } 176 177 /* workqueue callback */ 178 static void fb_deferred_io_work(struct work_struct *work) 179 { 180 struct fb_info *info = container_of(work, struct fb_info, 181 deferred_work.work); 182 struct list_head *node, *next; 183 struct page *cur; 184 struct fb_deferred_io *fbdefio = info->fbdefio; 185 186 /* here we mkclean the pages, then do all deferred IO */ 187 mutex_lock(&fbdefio->lock); 188 list_for_each_entry(cur, &fbdefio->pagelist, lru) { 189 lock_page(cur); 190 page_mkclean(cur); 191 unlock_page(cur); 192 } 193 194 /* driver's callback with pagelist */ 195 fbdefio->deferred_io(info, &fbdefio->pagelist); 196 197 /* clear the list */ 198 list_for_each_safe(node, next, &fbdefio->pagelist) { 199 list_del(node); 200 } 201 mutex_unlock(&fbdefio->lock); 202 } 203 204 void fb_deferred_io_init(struct fb_info *info) 205 { 206 struct fb_deferred_io *fbdefio = info->fbdefio; 207 208 BUG_ON(!fbdefio); 209 mutex_init(&fbdefio->lock); 210 info->fbops->fb_mmap = fb_deferred_io_mmap; 211 INIT_DELAYED_WORK(&info->deferred_work, fb_deferred_io_work); 212 INIT_LIST_HEAD(&fbdefio->pagelist); 213 if (fbdefio->delay == 0) /* set a default of 1 s */ 214 fbdefio->delay = HZ; 215 } 216 EXPORT_SYMBOL_GPL(fb_deferred_io_init); 217 218 void fb_deferred_io_open(struct fb_info *info, 219 struct inode *inode, 220 struct file *file) 221 { 222 file->f_mapping->a_ops = &fb_deferred_io_aops; 223 } 224 EXPORT_SYMBOL_GPL(fb_deferred_io_open); 225 226 void fb_deferred_io_cleanup(struct fb_info *info) 227 { 228 struct fb_deferred_io *fbdefio = info->fbdefio; 229 struct page *page; 230 int i; 231 232 BUG_ON(!fbdefio); 233 cancel_delayed_work_sync(&info->deferred_work); 234 235 /* clear out the mapping that we setup */ 236 for (i = 0 ; i < info->fix.smem_len; i += PAGE_SIZE) { 237 page = fb_deferred_io_page(info, i); 238 page->mapping = NULL; 239 } 240 241 info->fbops->fb_mmap = NULL; 242 mutex_destroy(&fbdefio->lock); 243 } 244 EXPORT_SYMBOL_GPL(fb_deferred_io_cleanup); 245