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 74 BUG_ON(!io); 75 if (io->page) 76 put_page(io->page); 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 /* 86 * check a range of space and convert unwritten extents to written. 87 * 88 * Called with inode->i_mutex; we depend on this when we manipulate 89 * io->flag, since we could otherwise race with ext4_flush_completed_IO() 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 int ret = 0; 97 98 ext4_debug("ext4_end_io_nolock: io 0x%p from inode %lu,list->next 0x%p," 99 "list->prev 0x%p\n", 100 io, inode->i_ino, io->list.next, io->list.prev); 101 102 ret = ext4_convert_unwritten_extents(inode, offset, size); 103 if (ret < 0) { 104 ext4_msg(inode->i_sb, KERN_EMERG, 105 "failed to convert unwritten extents to written " 106 "extents -- potential data loss! " 107 "(inode %lu, offset %llu, size %zd, error %d)", 108 inode->i_ino, offset, size, ret); 109 } 110 111 if (io->iocb) 112 aio_complete(io->iocb, io->result, 0); 113 114 /* Wake up anyone waiting on unwritten extent conversion */ 115 if (atomic_dec_and_test(&EXT4_I(inode)->i_aiodio_unwritten)) 116 wake_up_all(ext4_ioend_wq(io->inode)); 117 return ret; 118 } 119 120 /* 121 * work on completed aio dio IO, to convert unwritten extents to extents 122 */ 123 static void ext4_end_io_work(struct work_struct *work) 124 { 125 ext4_io_end_t *io = container_of(work, ext4_io_end_t, work); 126 struct inode *inode = io->inode; 127 struct ext4_inode_info *ei = EXT4_I(inode); 128 unsigned long flags; 129 130 spin_lock_irqsave(&ei->i_completed_io_lock, flags); 131 if (list_empty(&io->list)) { 132 spin_unlock_irqrestore(&ei->i_completed_io_lock, flags); 133 goto free; 134 } 135 136 if (!mutex_trylock(&inode->i_mutex)) { 137 spin_unlock_irqrestore(&ei->i_completed_io_lock, flags); 138 /* 139 * Requeue the work instead of waiting so that the work 140 * items queued after this can be processed. 141 */ 142 queue_work(EXT4_SB(inode->i_sb)->dio_unwritten_wq, &io->work); 143 /* 144 * To prevent the ext4-dio-unwritten thread from keeping 145 * requeueing end_io requests and occupying cpu for too long, 146 * yield the cpu if it sees an end_io request that has already 147 * been requeued. 148 */ 149 if (io->flag & EXT4_IO_END_QUEUED) 150 yield(); 151 io->flag |= EXT4_IO_END_QUEUED; 152 return; 153 } 154 list_del_init(&io->list); 155 spin_unlock_irqrestore(&ei->i_completed_io_lock, flags); 156 (void) ext4_end_io_nolock(io); 157 mutex_unlock(&inode->i_mutex); 158 free: 159 ext4_free_io_end(io); 160 } 161 162 ext4_io_end_t *ext4_init_io_end(struct inode *inode, gfp_t flags) 163 { 164 ext4_io_end_t *io = kmem_cache_zalloc(io_end_cachep, flags); 165 if (io) { 166 atomic_inc(&EXT4_I(inode)->i_ioend_count); 167 io->inode = inode; 168 INIT_WORK(&io->work, ext4_end_io_work); 169 INIT_LIST_HEAD(&io->list); 170 } 171 return io; 172 } 173 174 /* 175 * Print an buffer I/O error compatible with the fs/buffer.c. This 176 * provides compatibility with dmesg scrapers that look for a specific 177 * buffer I/O error message. We really need a unified error reporting 178 * structure to userspace ala Digital Unix's uerf system, but it's 179 * probably not going to happen in my lifetime, due to LKML politics... 180 */ 181 static void buffer_io_error(struct buffer_head *bh) 182 { 183 char b[BDEVNAME_SIZE]; 184 printk(KERN_ERR "Buffer I/O error on device %s, logical block %llu\n", 185 bdevname(bh->b_bdev, b), 186 (unsigned long long)bh->b_blocknr); 187 } 188 189 static void ext4_end_bio(struct bio *bio, int error) 190 { 191 ext4_io_end_t *io_end = bio->bi_private; 192 struct workqueue_struct *wq; 193 struct inode *inode; 194 unsigned long flags; 195 int i; 196 sector_t bi_sector = bio->bi_sector; 197 198 BUG_ON(!io_end); 199 bio->bi_private = NULL; 200 bio->bi_end_io = NULL; 201 if (test_bit(BIO_UPTODATE, &bio->bi_flags)) 202 error = 0; 203 bio_put(bio); 204 205 for (i = 0; i < io_end->num_io_pages; i++) { 206 struct page *page = io_end->pages[i]->p_page; 207 struct buffer_head *bh, *head; 208 loff_t offset; 209 loff_t io_end_offset; 210 211 if (error) { 212 SetPageError(page); 213 set_bit(AS_EIO, &page->mapping->flags); 214 head = page_buffers(page); 215 BUG_ON(!head); 216 217 io_end_offset = io_end->offset + io_end->size; 218 219 offset = (sector_t) page->index << PAGE_CACHE_SHIFT; 220 bh = head; 221 do { 222 if ((offset >= io_end->offset) && 223 (offset+bh->b_size <= io_end_offset)) 224 buffer_io_error(bh); 225 226 offset += bh->b_size; 227 bh = bh->b_this_page; 228 } while (bh != head); 229 } 230 231 put_io_page(io_end->pages[i]); 232 } 233 io_end->num_io_pages = 0; 234 inode = io_end->inode; 235 236 if (error) { 237 io_end->flag |= EXT4_IO_END_ERROR; 238 ext4_warning(inode->i_sb, "I/O error writing to inode %lu " 239 "(offset %llu size %ld starting block %llu)", 240 inode->i_ino, 241 (unsigned long long) io_end->offset, 242 (long) io_end->size, 243 (unsigned long long) 244 bi_sector >> (inode->i_blkbits - 9)); 245 } 246 247 if (!(io_end->flag & EXT4_IO_END_UNWRITTEN)) { 248 ext4_free_io_end(io_end); 249 return; 250 } 251 252 /* Add the io_end to per-inode completed io list*/ 253 spin_lock_irqsave(&EXT4_I(inode)->i_completed_io_lock, flags); 254 list_add_tail(&io_end->list, &EXT4_I(inode)->i_completed_io_list); 255 spin_unlock_irqrestore(&EXT4_I(inode)->i_completed_io_lock, flags); 256 257 wq = EXT4_SB(inode->i_sb)->dio_unwritten_wq; 258 /* queue the work to convert unwritten extents to written */ 259 queue_work(wq, &io_end->work); 260 } 261 262 void ext4_io_submit(struct ext4_io_submit *io) 263 { 264 struct bio *bio = io->io_bio; 265 266 if (bio) { 267 bio_get(io->io_bio); 268 submit_bio(io->io_op, io->io_bio); 269 BUG_ON(bio_flagged(io->io_bio, BIO_EOPNOTSUPP)); 270 bio_put(io->io_bio); 271 } 272 io->io_bio = NULL; 273 io->io_op = 0; 274 io->io_end = NULL; 275 } 276 277 static int io_submit_init(struct ext4_io_submit *io, 278 struct inode *inode, 279 struct writeback_control *wbc, 280 struct buffer_head *bh) 281 { 282 ext4_io_end_t *io_end; 283 struct page *page = bh->b_page; 284 int nvecs = bio_get_nr_vecs(bh->b_bdev); 285 struct bio *bio; 286 287 io_end = ext4_init_io_end(inode, GFP_NOFS); 288 if (!io_end) 289 return -ENOMEM; 290 bio = bio_alloc(GFP_NOIO, min(nvecs, BIO_MAX_PAGES)); 291 bio->bi_sector = bh->b_blocknr * (bh->b_size >> 9); 292 bio->bi_bdev = bh->b_bdev; 293 bio->bi_private = io->io_end = io_end; 294 bio->bi_end_io = ext4_end_bio; 295 296 io_end->offset = (page->index << PAGE_CACHE_SHIFT) + bh_offset(bh); 297 298 io->io_bio = bio; 299 io->io_op = (wbc->sync_mode == WB_SYNC_ALL ? WRITE_SYNC : WRITE); 300 io->io_next_block = bh->b_blocknr; 301 return 0; 302 } 303 304 static int io_submit_add_bh(struct ext4_io_submit *io, 305 struct ext4_io_page *io_page, 306 struct inode *inode, 307 struct writeback_control *wbc, 308 struct buffer_head *bh) 309 { 310 ext4_io_end_t *io_end; 311 int ret; 312 313 if (buffer_new(bh)) { 314 clear_buffer_new(bh); 315 unmap_underlying_metadata(bh->b_bdev, bh->b_blocknr); 316 } 317 318 if (!buffer_mapped(bh) || buffer_delay(bh)) { 319 if (!buffer_mapped(bh)) 320 clear_buffer_dirty(bh); 321 if (io->io_bio) 322 ext4_io_submit(io); 323 return 0; 324 } 325 326 if (io->io_bio && bh->b_blocknr != io->io_next_block) { 327 submit_and_retry: 328 ext4_io_submit(io); 329 } 330 if (io->io_bio == NULL) { 331 ret = io_submit_init(io, inode, wbc, bh); 332 if (ret) 333 return ret; 334 } 335 io_end = io->io_end; 336 if ((io_end->num_io_pages >= MAX_IO_PAGES) && 337 (io_end->pages[io_end->num_io_pages-1] != io_page)) 338 goto submit_and_retry; 339 if (buffer_uninit(bh)) 340 ext4_set_io_unwritten_flag(inode, io_end); 341 io->io_end->size += bh->b_size; 342 io->io_next_block++; 343 ret = bio_add_page(io->io_bio, bh->b_page, bh->b_size, bh_offset(bh)); 344 if (ret != bh->b_size) 345 goto submit_and_retry; 346 if ((io_end->num_io_pages == 0) || 347 (io_end->pages[io_end->num_io_pages-1] != io_page)) { 348 io_end->pages[io_end->num_io_pages++] = io_page; 349 atomic_inc(&io_page->p_count); 350 } 351 return 0; 352 } 353 354 int ext4_bio_write_page(struct ext4_io_submit *io, 355 struct page *page, 356 int len, 357 struct writeback_control *wbc) 358 { 359 struct inode *inode = page->mapping->host; 360 unsigned block_start, block_end, blocksize; 361 struct ext4_io_page *io_page; 362 struct buffer_head *bh, *head; 363 int ret = 0; 364 365 blocksize = 1 << inode->i_blkbits; 366 367 BUG_ON(!PageLocked(page)); 368 BUG_ON(PageWriteback(page)); 369 370 io_page = kmem_cache_alloc(io_page_cachep, GFP_NOFS); 371 if (!io_page) { 372 set_page_dirty(page); 373 unlock_page(page); 374 return -ENOMEM; 375 } 376 io_page->p_page = page; 377 atomic_set(&io_page->p_count, 1); 378 get_page(page); 379 set_page_writeback(page); 380 ClearPageError(page); 381 382 for (bh = head = page_buffers(page), block_start = 0; 383 bh != head || !block_start; 384 block_start = block_end, bh = bh->b_this_page) { 385 386 block_end = block_start + blocksize; 387 if (block_start >= len) { 388 clear_buffer_dirty(bh); 389 set_buffer_uptodate(bh); 390 continue; 391 } 392 clear_buffer_dirty(bh); 393 ret = io_submit_add_bh(io, io_page, inode, wbc, bh); 394 if (ret) { 395 /* 396 * We only get here on ENOMEM. Not much else 397 * we can do but mark the page as dirty, and 398 * better luck next time. 399 */ 400 set_page_dirty(page); 401 break; 402 } 403 } 404 unlock_page(page); 405 /* 406 * If the page was truncated before we could do the writeback, 407 * or we had a memory allocation error while trying to write 408 * the first buffer head, we won't have submitted any pages for 409 * I/O. In that case we need to make sure we've cleared the 410 * PageWriteback bit from the page to prevent the system from 411 * wedging later on. 412 */ 413 put_io_page(io_page); 414 return ret; 415 } 416