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/module.h> 10 #include <linux/fs.h> 11 #include <linux/time.h> 12 #include <linux/jbd2.h> 13 #include <linux/highuid.h> 14 #include <linux/pagemap.h> 15 #include <linux/quotaops.h> 16 #include <linux/string.h> 17 #include <linux/buffer_head.h> 18 #include <linux/writeback.h> 19 #include <linux/pagevec.h> 20 #include <linux/mpage.h> 21 #include <linux/namei.h> 22 #include <linux/uio.h> 23 #include <linux/bio.h> 24 #include <linux/workqueue.h> 25 #include <linux/kernel.h> 26 #include <linux/slab.h> 27 28 #include "ext4_jbd2.h" 29 #include "xattr.h" 30 #include "acl.h" 31 #include "ext4_extents.h" 32 33 static struct kmem_cache *io_page_cachep, *io_end_cachep; 34 35 int __init ext4_init_pageio(void) 36 { 37 io_page_cachep = KMEM_CACHE(ext4_io_page, SLAB_RECLAIM_ACCOUNT); 38 if (io_page_cachep == NULL) 39 return -ENOMEM; 40 io_end_cachep = KMEM_CACHE(ext4_io_end, SLAB_RECLAIM_ACCOUNT); 41 if (io_end_cachep == NULL) { 42 kmem_cache_destroy(io_page_cachep); 43 return -ENOMEM; 44 } 45 return 0; 46 } 47 48 void ext4_exit_pageio(void) 49 { 50 kmem_cache_destroy(io_end_cachep); 51 kmem_cache_destroy(io_page_cachep); 52 } 53 54 void ext4_ioend_wait(struct inode *inode) 55 { 56 wait_queue_head_t *wq = ext4_ioend_wq(inode); 57 58 wait_event(*wq, (atomic_read(&EXT4_I(inode)->i_ioend_count) == 0)); 59 } 60 61 static void put_io_page(struct ext4_io_page *io_page) 62 { 63 if (atomic_dec_and_test(&io_page->p_count)) { 64 end_page_writeback(io_page->p_page); 65 put_page(io_page->p_page); 66 kmem_cache_free(io_page_cachep, io_page); 67 } 68 } 69 70 void ext4_free_io_end(ext4_io_end_t *io) 71 { 72 int i; 73 wait_queue_head_t *wq; 74 75 BUG_ON(!io); 76 if (io->page) 77 put_page(io->page); 78 for (i = 0; i < io->num_io_pages; i++) 79 put_io_page(io->pages[i]); 80 io->num_io_pages = 0; 81 wq = ext4_ioend_wq(io->inode); 82 if (atomic_dec_and_test(&EXT4_I(io->inode)->i_ioend_count) && 83 waitqueue_active(wq)) 84 wake_up_all(wq); 85 kmem_cache_free(io_end_cachep, io); 86 } 87 88 /* 89 * check a range of space and convert unwritten extents to written. 90 */ 91 int ext4_end_io_nolock(ext4_io_end_t *io) 92 { 93 struct inode *inode = io->inode; 94 loff_t offset = io->offset; 95 ssize_t size = io->size; 96 wait_queue_head_t *wq; 97 int ret = 0; 98 99 ext4_debug("ext4_end_io_nolock: io 0x%p from inode %lu,list->next 0x%p," 100 "list->prev 0x%p\n", 101 io, inode->i_ino, io->list.next, io->list.prev); 102 103 if (list_empty(&io->list)) 104 return ret; 105 106 if (!(io->flag & EXT4_IO_END_UNWRITTEN)) 107 return ret; 108 109 ret = ext4_convert_unwritten_extents(inode, offset, size); 110 if (ret < 0) { 111 printk(KERN_EMERG "%s: failed to convert unwritten " 112 "extents to written extents, error is %d " 113 "io is still on inode %lu aio dio list\n", 114 __func__, ret, inode->i_ino); 115 return ret; 116 } 117 118 if (io->iocb) 119 aio_complete(io->iocb, io->result, 0); 120 /* clear the DIO AIO unwritten flag */ 121 if (io->flag & EXT4_IO_END_UNWRITTEN) { 122 io->flag &= ~EXT4_IO_END_UNWRITTEN; 123 /* Wake up anyone waiting on unwritten extent conversion */ 124 wq = ext4_ioend_wq(io->inode); 125 if (atomic_dec_and_test(&EXT4_I(inode)->i_aiodio_unwritten) && 126 waitqueue_active(wq)) { 127 wake_up_all(wq); 128 } 129 } 130 131 return ret; 132 } 133 134 /* 135 * work on completed aio dio IO, to convert unwritten extents to extents 136 */ 137 static void ext4_end_io_work(struct work_struct *work) 138 { 139 ext4_io_end_t *io = container_of(work, ext4_io_end_t, work); 140 struct inode *inode = io->inode; 141 struct ext4_inode_info *ei = EXT4_I(inode); 142 unsigned long flags; 143 int ret; 144 145 if (!mutex_trylock(&inode->i_mutex)) { 146 /* 147 * Requeue the work instead of waiting so that the work 148 * items queued after this can be processed. 149 */ 150 queue_work(EXT4_SB(inode->i_sb)->dio_unwritten_wq, &io->work); 151 /* 152 * To prevent the ext4-dio-unwritten thread from keeping 153 * requeueing end_io requests and occupying cpu for too long, 154 * yield the cpu if it sees an end_io request that has already 155 * been requeued. 156 */ 157 if (io->flag & EXT4_IO_END_QUEUED) 158 yield(); 159 io->flag |= EXT4_IO_END_QUEUED; 160 return; 161 } 162 ret = ext4_end_io_nolock(io); 163 if (ret < 0) { 164 mutex_unlock(&inode->i_mutex); 165 return; 166 } 167 168 spin_lock_irqsave(&ei->i_completed_io_lock, flags); 169 if (!list_empty(&io->list)) 170 list_del_init(&io->list); 171 spin_unlock_irqrestore(&ei->i_completed_io_lock, flags); 172 mutex_unlock(&inode->i_mutex); 173 ext4_free_io_end(io); 174 } 175 176 ext4_io_end_t *ext4_init_io_end(struct inode *inode, gfp_t flags) 177 { 178 ext4_io_end_t *io = kmem_cache_zalloc(io_end_cachep, flags); 179 if (io) { 180 atomic_inc(&EXT4_I(inode)->i_ioend_count); 181 io->inode = inode; 182 INIT_WORK(&io->work, ext4_end_io_work); 183 INIT_LIST_HEAD(&io->list); 184 } 185 return io; 186 } 187 188 /* 189 * Print an buffer I/O error compatible with the fs/buffer.c. This 190 * provides compatibility with dmesg scrapers that look for a specific 191 * buffer I/O error message. We really need a unified error reporting 192 * structure to userspace ala Digital Unix's uerf system, but it's 193 * probably not going to happen in my lifetime, due to LKML politics... 194 */ 195 static void buffer_io_error(struct buffer_head *bh) 196 { 197 char b[BDEVNAME_SIZE]; 198 printk(KERN_ERR "Buffer I/O error on device %s, logical block %llu\n", 199 bdevname(bh->b_bdev, b), 200 (unsigned long long)bh->b_blocknr); 201 } 202 203 static void ext4_end_bio(struct bio *bio, int error) 204 { 205 ext4_io_end_t *io_end = bio->bi_private; 206 struct workqueue_struct *wq; 207 struct inode *inode; 208 unsigned long flags; 209 int i; 210 sector_t bi_sector = bio->bi_sector; 211 212 BUG_ON(!io_end); 213 bio->bi_private = NULL; 214 bio->bi_end_io = NULL; 215 if (test_bit(BIO_UPTODATE, &bio->bi_flags)) 216 error = 0; 217 bio_put(bio); 218 219 for (i = 0; i < io_end->num_io_pages; i++) { 220 struct page *page = io_end->pages[i]->p_page; 221 struct buffer_head *bh, *head; 222 loff_t offset; 223 loff_t io_end_offset; 224 225 if (error) { 226 SetPageError(page); 227 set_bit(AS_EIO, &page->mapping->flags); 228 head = page_buffers(page); 229 BUG_ON(!head); 230 231 io_end_offset = io_end->offset + io_end->size; 232 233 offset = (sector_t) page->index << PAGE_CACHE_SHIFT; 234 bh = head; 235 do { 236 if ((offset >= io_end->offset) && 237 (offset+bh->b_size <= io_end_offset)) 238 buffer_io_error(bh); 239 240 offset += bh->b_size; 241 bh = bh->b_this_page; 242 } while (bh != head); 243 } 244 245 put_io_page(io_end->pages[i]); 246 } 247 io_end->num_io_pages = 0; 248 inode = io_end->inode; 249 250 if (error) { 251 io_end->flag |= EXT4_IO_END_ERROR; 252 ext4_warning(inode->i_sb, "I/O error writing to inode %lu " 253 "(offset %llu size %ld starting block %llu)", 254 inode->i_ino, 255 (unsigned long long) io_end->offset, 256 (long) io_end->size, 257 (unsigned long long) 258 bi_sector >> (inode->i_blkbits - 9)); 259 } 260 261 if (!(io_end->flag & EXT4_IO_END_UNWRITTEN)) { 262 ext4_free_io_end(io_end); 263 return; 264 } 265 266 /* Add the io_end to per-inode completed io list*/ 267 spin_lock_irqsave(&EXT4_I(inode)->i_completed_io_lock, flags); 268 list_add_tail(&io_end->list, &EXT4_I(inode)->i_completed_io_list); 269 spin_unlock_irqrestore(&EXT4_I(inode)->i_completed_io_lock, flags); 270 271 wq = EXT4_SB(inode->i_sb)->dio_unwritten_wq; 272 /* queue the work to convert unwritten extents to written */ 273 queue_work(wq, &io_end->work); 274 } 275 276 void ext4_io_submit(struct ext4_io_submit *io) 277 { 278 struct bio *bio = io->io_bio; 279 280 if (bio) { 281 bio_get(io->io_bio); 282 submit_bio(io->io_op, io->io_bio); 283 BUG_ON(bio_flagged(io->io_bio, BIO_EOPNOTSUPP)); 284 bio_put(io->io_bio); 285 } 286 io->io_bio = NULL; 287 io->io_op = 0; 288 io->io_end = NULL; 289 } 290 291 static int io_submit_init(struct ext4_io_submit *io, 292 struct inode *inode, 293 struct writeback_control *wbc, 294 struct buffer_head *bh) 295 { 296 ext4_io_end_t *io_end; 297 struct page *page = bh->b_page; 298 int nvecs = bio_get_nr_vecs(bh->b_bdev); 299 struct bio *bio; 300 301 io_end = ext4_init_io_end(inode, GFP_NOFS); 302 if (!io_end) 303 return -ENOMEM; 304 bio = bio_alloc(GFP_NOIO, min(nvecs, BIO_MAX_PAGES)); 305 bio->bi_sector = bh->b_blocknr * (bh->b_size >> 9); 306 bio->bi_bdev = bh->b_bdev; 307 bio->bi_private = io->io_end = io_end; 308 bio->bi_end_io = ext4_end_bio; 309 310 io_end->offset = (page->index << PAGE_CACHE_SHIFT) + bh_offset(bh); 311 312 io->io_bio = bio; 313 io->io_op = (wbc->sync_mode == WB_SYNC_ALL ? WRITE_SYNC : WRITE); 314 io->io_next_block = bh->b_blocknr; 315 return 0; 316 } 317 318 static int io_submit_add_bh(struct ext4_io_submit *io, 319 struct ext4_io_page *io_page, 320 struct inode *inode, 321 struct writeback_control *wbc, 322 struct buffer_head *bh) 323 { 324 ext4_io_end_t *io_end; 325 int ret; 326 327 if (buffer_new(bh)) { 328 clear_buffer_new(bh); 329 unmap_underlying_metadata(bh->b_bdev, bh->b_blocknr); 330 } 331 332 if (!buffer_mapped(bh) || buffer_delay(bh)) { 333 if (!buffer_mapped(bh)) 334 clear_buffer_dirty(bh); 335 if (io->io_bio) 336 ext4_io_submit(io); 337 return 0; 338 } 339 340 if (io->io_bio && bh->b_blocknr != io->io_next_block) { 341 submit_and_retry: 342 ext4_io_submit(io); 343 } 344 if (io->io_bio == NULL) { 345 ret = io_submit_init(io, inode, wbc, bh); 346 if (ret) 347 return ret; 348 } 349 io_end = io->io_end; 350 if ((io_end->num_io_pages >= MAX_IO_PAGES) && 351 (io_end->pages[io_end->num_io_pages-1] != io_page)) 352 goto submit_and_retry; 353 if (buffer_uninit(bh) && !(io_end->flag & EXT4_IO_END_UNWRITTEN)) { 354 io_end->flag |= EXT4_IO_END_UNWRITTEN; 355 atomic_inc(&EXT4_I(inode)->i_aiodio_unwritten); 356 } 357 io->io_end->size += bh->b_size; 358 io->io_next_block++; 359 ret = bio_add_page(io->io_bio, bh->b_page, bh->b_size, bh_offset(bh)); 360 if (ret != bh->b_size) 361 goto submit_and_retry; 362 if ((io_end->num_io_pages == 0) || 363 (io_end->pages[io_end->num_io_pages-1] != io_page)) { 364 io_end->pages[io_end->num_io_pages++] = io_page; 365 atomic_inc(&io_page->p_count); 366 } 367 return 0; 368 } 369 370 int ext4_bio_write_page(struct ext4_io_submit *io, 371 struct page *page, 372 int len, 373 struct writeback_control *wbc) 374 { 375 struct inode *inode = page->mapping->host; 376 unsigned block_start, block_end, blocksize; 377 struct ext4_io_page *io_page; 378 struct buffer_head *bh, *head; 379 int ret = 0; 380 381 blocksize = 1 << inode->i_blkbits; 382 383 BUG_ON(!PageLocked(page)); 384 BUG_ON(PageWriteback(page)); 385 386 io_page = kmem_cache_alloc(io_page_cachep, GFP_NOFS); 387 if (!io_page) { 388 set_page_dirty(page); 389 unlock_page(page); 390 return -ENOMEM; 391 } 392 io_page->p_page = page; 393 atomic_set(&io_page->p_count, 1); 394 get_page(page); 395 set_page_writeback(page); 396 ClearPageError(page); 397 398 for (bh = head = page_buffers(page), block_start = 0; 399 bh != head || !block_start; 400 block_start = block_end, bh = bh->b_this_page) { 401 402 block_end = block_start + blocksize; 403 if (block_start >= len) { 404 clear_buffer_dirty(bh); 405 set_buffer_uptodate(bh); 406 continue; 407 } 408 clear_buffer_dirty(bh); 409 ret = io_submit_add_bh(io, io_page, inode, wbc, bh); 410 if (ret) { 411 /* 412 * We only get here on ENOMEM. Not much else 413 * we can do but mark the page as dirty, and 414 * better luck next time. 415 */ 416 set_page_dirty(page); 417 break; 418 } 419 } 420 unlock_page(page); 421 /* 422 * If the page was truncated before we could do the writeback, 423 * or we had a memory allocation error while trying to write 424 * the first buffer head, we won't have submitted any pages for 425 * I/O. In that case we need to make sure we've cleared the 426 * PageWriteback bit from the page to prevent the system from 427 * wedging later on. 428 */ 429 put_io_page(io_page); 430 return ret; 431 } 432