1 /* 2 * linux/fs/ext4/page-io.c 3 * 4 * This contains the new page_io functions for ext4 5 * 6 * Written by Theodore Ts'o, 2010. 7 */ 8 9 #include <linux/fs.h> 10 #include <linux/time.h> 11 #include <linux/jbd2.h> 12 #include <linux/highuid.h> 13 #include <linux/pagemap.h> 14 #include <linux/quotaops.h> 15 #include <linux/string.h> 16 #include <linux/buffer_head.h> 17 #include <linux/writeback.h> 18 #include <linux/pagevec.h> 19 #include <linux/mpage.h> 20 #include <linux/namei.h> 21 #include <linux/uio.h> 22 #include <linux/bio.h> 23 #include <linux/workqueue.h> 24 #include <linux/kernel.h> 25 #include <linux/slab.h> 26 #include <linux/mm.h> 27 28 #include "ext4_jbd2.h" 29 #include "xattr.h" 30 #include "acl.h" 31 32 static struct kmem_cache *io_page_cachep, *io_end_cachep; 33 34 int __init ext4_init_pageio(void) 35 { 36 io_page_cachep = KMEM_CACHE(ext4_io_page, SLAB_RECLAIM_ACCOUNT); 37 if (io_page_cachep == NULL) 38 return -ENOMEM; 39 io_end_cachep = KMEM_CACHE(ext4_io_end, SLAB_RECLAIM_ACCOUNT); 40 if (io_end_cachep == NULL) { 41 kmem_cache_destroy(io_page_cachep); 42 return -ENOMEM; 43 } 44 return 0; 45 } 46 47 void ext4_exit_pageio(void) 48 { 49 kmem_cache_destroy(io_end_cachep); 50 kmem_cache_destroy(io_page_cachep); 51 } 52 53 void ext4_ioend_wait(struct inode *inode) 54 { 55 wait_queue_head_t *wq = ext4_ioend_wq(inode); 56 57 wait_event(*wq, (atomic_read(&EXT4_I(inode)->i_ioend_count) == 0)); 58 } 59 60 static void put_io_page(struct ext4_io_page *io_page) 61 { 62 if (atomic_dec_and_test(&io_page->p_count)) { 63 end_page_writeback(io_page->p_page); 64 put_page(io_page->p_page); 65 kmem_cache_free(io_page_cachep, io_page); 66 } 67 } 68 69 void ext4_free_io_end(ext4_io_end_t *io) 70 { 71 int i; 72 73 BUG_ON(!io); 74 BUG_ON(!list_empty(&io->list)); 75 BUG_ON(io->flag & EXT4_IO_END_UNWRITTEN); 76 77 for (i = 0; i < io->num_io_pages; i++) 78 put_io_page(io->pages[i]); 79 io->num_io_pages = 0; 80 if (atomic_dec_and_test(&EXT4_I(io->inode)->i_ioend_count)) 81 wake_up_all(ext4_ioend_wq(io->inode)); 82 kmem_cache_free(io_end_cachep, io); 83 } 84 85 /* check a range of space and convert unwritten extents to written. */ 86 static int ext4_end_io(ext4_io_end_t *io) 87 { 88 struct inode *inode = io->inode; 89 loff_t offset = io->offset; 90 ssize_t size = io->size; 91 int ret = 0; 92 93 ext4_debug("ext4_end_io_nolock: io 0x%p from inode %lu,list->next 0x%p," 94 "list->prev 0x%p\n", 95 io, inode->i_ino, io->list.next, io->list.prev); 96 97 ret = ext4_convert_unwritten_extents(inode, offset, size); 98 if (ret < 0) { 99 ext4_msg(inode->i_sb, KERN_EMERG, 100 "failed to convert unwritten extents to written " 101 "extents -- potential data loss! " 102 "(inode %lu, offset %llu, size %zd, error %d)", 103 inode->i_ino, offset, size, ret); 104 } 105 /* Wake up anyone waiting on unwritten extent conversion */ 106 if (atomic_dec_and_test(&EXT4_I(inode)->i_unwritten)) 107 wake_up_all(ext4_ioend_wq(inode)); 108 if (io->flag & EXT4_IO_END_DIRECT) 109 inode_dio_done(inode); 110 if (io->iocb) 111 aio_complete(io->iocb, io->result, 0); 112 return ret; 113 } 114 115 static void dump_completed_IO(struct inode *inode) 116 { 117 #ifdef EXT4FS_DEBUG 118 struct list_head *cur, *before, *after; 119 ext4_io_end_t *io, *io0, *io1; 120 121 if (list_empty(&EXT4_I(inode)->i_completed_io_list)) { 122 ext4_debug("inode %lu completed_io list is empty\n", 123 inode->i_ino); 124 return; 125 } 126 127 ext4_debug("Dump inode %lu completed_io list\n", inode->i_ino); 128 list_for_each_entry(io, &EXT4_I(inode)->i_completed_io_list, list) { 129 cur = &io->list; 130 before = cur->prev; 131 io0 = container_of(before, ext4_io_end_t, list); 132 after = cur->next; 133 io1 = container_of(after, ext4_io_end_t, list); 134 135 ext4_debug("io 0x%p from inode %lu,prev 0x%p,next 0x%p\n", 136 io, inode->i_ino, io0, io1); 137 } 138 #endif 139 } 140 141 /* Add the io_end to per-inode completed end_io list. */ 142 void ext4_add_complete_io(ext4_io_end_t *io_end) 143 { 144 struct ext4_inode_info *ei = EXT4_I(io_end->inode); 145 struct workqueue_struct *wq; 146 unsigned long flags; 147 148 BUG_ON(!(io_end->flag & EXT4_IO_END_UNWRITTEN)); 149 wq = EXT4_SB(io_end->inode->i_sb)->dio_unwritten_wq; 150 151 spin_lock_irqsave(&ei->i_completed_io_lock, flags); 152 if (list_empty(&ei->i_completed_io_list)) 153 queue_work(wq, &ei->i_unwritten_work); 154 list_add_tail(&io_end->list, &ei->i_completed_io_list); 155 spin_unlock_irqrestore(&ei->i_completed_io_lock, flags); 156 } 157 158 static int ext4_do_flush_completed_IO(struct inode *inode) 159 { 160 ext4_io_end_t *io; 161 struct list_head unwritten; 162 unsigned long flags; 163 struct ext4_inode_info *ei = EXT4_I(inode); 164 int err, ret = 0; 165 166 spin_lock_irqsave(&ei->i_completed_io_lock, flags); 167 dump_completed_IO(inode); 168 list_replace_init(&ei->i_completed_io_list, &unwritten); 169 spin_unlock_irqrestore(&ei->i_completed_io_lock, flags); 170 171 while (!list_empty(&unwritten)) { 172 io = list_entry(unwritten.next, ext4_io_end_t, list); 173 BUG_ON(!(io->flag & EXT4_IO_END_UNWRITTEN)); 174 list_del_init(&io->list); 175 176 err = ext4_end_io(io); 177 if (unlikely(!ret && err)) 178 ret = err; 179 io->flag &= ~EXT4_IO_END_UNWRITTEN; 180 ext4_free_io_end(io); 181 } 182 return ret; 183 } 184 185 /* 186 * work on completed aio dio IO, to convert unwritten extents to extents 187 */ 188 void ext4_end_io_work(struct work_struct *work) 189 { 190 struct ext4_inode_info *ei = container_of(work, struct ext4_inode_info, 191 i_unwritten_work); 192 ext4_do_flush_completed_IO(&ei->vfs_inode); 193 } 194 195 int ext4_flush_unwritten_io(struct inode *inode) 196 { 197 int ret; 198 WARN_ON_ONCE(!mutex_is_locked(&inode->i_mutex) && 199 !(inode->i_state & I_FREEING)); 200 ret = ext4_do_flush_completed_IO(inode); 201 ext4_unwritten_wait(inode); 202 return ret; 203 } 204 205 ext4_io_end_t *ext4_init_io_end(struct inode *inode, gfp_t flags) 206 { 207 ext4_io_end_t *io = kmem_cache_zalloc(io_end_cachep, flags); 208 if (io) { 209 atomic_inc(&EXT4_I(inode)->i_ioend_count); 210 io->inode = inode; 211 INIT_LIST_HEAD(&io->list); 212 } 213 return io; 214 } 215 216 /* 217 * Print an buffer I/O error compatible with the fs/buffer.c. This 218 * provides compatibility with dmesg scrapers that look for a specific 219 * buffer I/O error message. We really need a unified error reporting 220 * structure to userspace ala Digital Unix's uerf system, but it's 221 * probably not going to happen in my lifetime, due to LKML politics... 222 */ 223 static void buffer_io_error(struct buffer_head *bh) 224 { 225 char b[BDEVNAME_SIZE]; 226 printk(KERN_ERR "Buffer I/O error on device %s, logical block %llu\n", 227 bdevname(bh->b_bdev, b), 228 (unsigned long long)bh->b_blocknr); 229 } 230 231 static void ext4_end_bio(struct bio *bio, int error) 232 { 233 ext4_io_end_t *io_end = bio->bi_private; 234 struct inode *inode; 235 int i; 236 sector_t bi_sector = bio->bi_sector; 237 238 BUG_ON(!io_end); 239 bio->bi_private = NULL; 240 bio->bi_end_io = NULL; 241 if (test_bit(BIO_UPTODATE, &bio->bi_flags)) 242 error = 0; 243 bio_put(bio); 244 245 for (i = 0; i < io_end->num_io_pages; i++) { 246 struct page *page = io_end->pages[i]->p_page; 247 struct buffer_head *bh, *head; 248 loff_t offset; 249 loff_t io_end_offset; 250 251 if (error) { 252 SetPageError(page); 253 set_bit(AS_EIO, &page->mapping->flags); 254 head = page_buffers(page); 255 BUG_ON(!head); 256 257 io_end_offset = io_end->offset + io_end->size; 258 259 offset = (sector_t) page->index << PAGE_CACHE_SHIFT; 260 bh = head; 261 do { 262 if ((offset >= io_end->offset) && 263 (offset+bh->b_size <= io_end_offset)) 264 buffer_io_error(bh); 265 266 offset += bh->b_size; 267 bh = bh->b_this_page; 268 } while (bh != head); 269 } 270 271 put_io_page(io_end->pages[i]); 272 } 273 io_end->num_io_pages = 0; 274 inode = io_end->inode; 275 276 if (error) { 277 io_end->flag |= EXT4_IO_END_ERROR; 278 ext4_warning(inode->i_sb, "I/O error writing to inode %lu " 279 "(offset %llu size %ld starting block %llu)", 280 inode->i_ino, 281 (unsigned long long) io_end->offset, 282 (long) io_end->size, 283 (unsigned long long) 284 bi_sector >> (inode->i_blkbits - 9)); 285 } 286 287 if (!(io_end->flag & EXT4_IO_END_UNWRITTEN)) { 288 ext4_free_io_end(io_end); 289 return; 290 } 291 292 ext4_add_complete_io(io_end); 293 } 294 295 void ext4_io_submit(struct ext4_io_submit *io) 296 { 297 struct bio *bio = io->io_bio; 298 299 if (bio) { 300 bio_get(io->io_bio); 301 submit_bio(io->io_op, io->io_bio); 302 BUG_ON(bio_flagged(io->io_bio, BIO_EOPNOTSUPP)); 303 bio_put(io->io_bio); 304 } 305 io->io_bio = NULL; 306 io->io_op = 0; 307 io->io_end = NULL; 308 } 309 310 static int io_submit_init(struct ext4_io_submit *io, 311 struct inode *inode, 312 struct writeback_control *wbc, 313 struct buffer_head *bh) 314 { 315 ext4_io_end_t *io_end; 316 struct page *page = bh->b_page; 317 int nvecs = bio_get_nr_vecs(bh->b_bdev); 318 struct bio *bio; 319 320 io_end = ext4_init_io_end(inode, GFP_NOFS); 321 if (!io_end) 322 return -ENOMEM; 323 bio = bio_alloc(GFP_NOIO, min(nvecs, BIO_MAX_PAGES)); 324 bio->bi_sector = bh->b_blocknr * (bh->b_size >> 9); 325 bio->bi_bdev = bh->b_bdev; 326 bio->bi_private = io->io_end = io_end; 327 bio->bi_end_io = ext4_end_bio; 328 329 io_end->offset = (page->index << PAGE_CACHE_SHIFT) + bh_offset(bh); 330 331 io->io_bio = bio; 332 io->io_op = (wbc->sync_mode == WB_SYNC_ALL ? WRITE_SYNC : WRITE); 333 io->io_next_block = bh->b_blocknr; 334 return 0; 335 } 336 337 static int io_submit_add_bh(struct ext4_io_submit *io, 338 struct ext4_io_page *io_page, 339 struct inode *inode, 340 struct writeback_control *wbc, 341 struct buffer_head *bh) 342 { 343 ext4_io_end_t *io_end; 344 int ret; 345 346 if (buffer_new(bh)) { 347 clear_buffer_new(bh); 348 unmap_underlying_metadata(bh->b_bdev, bh->b_blocknr); 349 } 350 351 if (io->io_bio && bh->b_blocknr != io->io_next_block) { 352 submit_and_retry: 353 ext4_io_submit(io); 354 } 355 if (io->io_bio == NULL) { 356 ret = io_submit_init(io, inode, wbc, bh); 357 if (ret) 358 return ret; 359 } 360 io_end = io->io_end; 361 if ((io_end->num_io_pages >= MAX_IO_PAGES) && 362 (io_end->pages[io_end->num_io_pages-1] != io_page)) 363 goto submit_and_retry; 364 if (buffer_uninit(bh)) 365 ext4_set_io_unwritten_flag(inode, io_end); 366 io->io_end->size += bh->b_size; 367 io->io_next_block++; 368 ret = bio_add_page(io->io_bio, bh->b_page, bh->b_size, bh_offset(bh)); 369 if (ret != bh->b_size) 370 goto submit_and_retry; 371 if ((io_end->num_io_pages == 0) || 372 (io_end->pages[io_end->num_io_pages-1] != io_page)) { 373 io_end->pages[io_end->num_io_pages++] = io_page; 374 atomic_inc(&io_page->p_count); 375 } 376 return 0; 377 } 378 379 int ext4_bio_write_page(struct ext4_io_submit *io, 380 struct page *page, 381 int len, 382 struct writeback_control *wbc) 383 { 384 struct inode *inode = page->mapping->host; 385 unsigned block_start, block_end, blocksize; 386 struct ext4_io_page *io_page; 387 struct buffer_head *bh, *head; 388 int ret = 0; 389 390 blocksize = 1 << inode->i_blkbits; 391 392 BUG_ON(!PageLocked(page)); 393 BUG_ON(PageWriteback(page)); 394 395 io_page = kmem_cache_alloc(io_page_cachep, GFP_NOFS); 396 if (!io_page) { 397 redirty_page_for_writepage(wbc, page); 398 unlock_page(page); 399 return -ENOMEM; 400 } 401 io_page->p_page = page; 402 atomic_set(&io_page->p_count, 1); 403 get_page(page); 404 set_page_writeback(page); 405 ClearPageError(page); 406 407 for (bh = head = page_buffers(page), block_start = 0; 408 bh != head || !block_start; 409 block_start = block_end, bh = bh->b_this_page) { 410 411 block_end = block_start + blocksize; 412 if (block_start >= len) { 413 /* 414 * Comments copied from block_write_full_page_endio: 415 * 416 * The page straddles i_size. It must be zeroed out on 417 * each and every writepage invocation because it may 418 * be mmapped. "A file is mapped in multiples of the 419 * page size. For a file that is not a multiple of 420 * the page size, the remaining memory is zeroed when 421 * mapped, and writes to that region are not written 422 * out to the file." 423 */ 424 zero_user_segment(page, block_start, block_end); 425 clear_buffer_dirty(bh); 426 set_buffer_uptodate(bh); 427 continue; 428 } 429 if (!buffer_dirty(bh) || buffer_delay(bh) || 430 !buffer_mapped(bh) || buffer_unwritten(bh)) { 431 /* A hole? We can safely clear the dirty bit */ 432 if (!buffer_mapped(bh)) 433 clear_buffer_dirty(bh); 434 if (io->io_bio) 435 ext4_io_submit(io); 436 continue; 437 } 438 ret = io_submit_add_bh(io, io_page, inode, wbc, bh); 439 if (ret) { 440 /* 441 * We only get here on ENOMEM. Not much else 442 * we can do but mark the page as dirty, and 443 * better luck next time. 444 */ 445 redirty_page_for_writepage(wbc, page); 446 break; 447 } 448 clear_buffer_dirty(bh); 449 } 450 unlock_page(page); 451 /* 452 * If the page was truncated before we could do the writeback, 453 * or we had a memory allocation error while trying to write 454 * the first buffer head, we won't have submitted any pages for 455 * I/O. In that case we need to make sure we've cleared the 456 * PageWriteback bit from the page to prevent the system from 457 * wedging later on. 458 */ 459 put_io_page(io_page); 460 return ret; 461 } 462