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 mutex_lock(&inode->i_mutex); 146 ret = ext4_end_io_nolock(io); 147 if (ret < 0) { 148 mutex_unlock(&inode->i_mutex); 149 return; 150 } 151 152 spin_lock_irqsave(&ei->i_completed_io_lock, flags); 153 if (!list_empty(&io->list)) 154 list_del_init(&io->list); 155 spin_unlock_irqrestore(&ei->i_completed_io_lock, flags); 156 mutex_unlock(&inode->i_mutex); 157 ext4_free_io_end(io); 158 } 159 160 ext4_io_end_t *ext4_init_io_end(struct inode *inode, gfp_t flags) 161 { 162 ext4_io_end_t *io = kmem_cache_zalloc(io_end_cachep, flags); 163 if (io) { 164 atomic_inc(&EXT4_I(inode)->i_ioend_count); 165 io->inode = inode; 166 INIT_WORK(&io->work, ext4_end_io_work); 167 INIT_LIST_HEAD(&io->list); 168 } 169 return io; 170 } 171 172 /* 173 * Print an buffer I/O error compatible with the fs/buffer.c. This 174 * provides compatibility with dmesg scrapers that look for a specific 175 * buffer I/O error message. We really need a unified error reporting 176 * structure to userspace ala Digital Unix's uerf system, but it's 177 * probably not going to happen in my lifetime, due to LKML politics... 178 */ 179 static void buffer_io_error(struct buffer_head *bh) 180 { 181 char b[BDEVNAME_SIZE]; 182 printk(KERN_ERR "Buffer I/O error on device %s, logical block %llu\n", 183 bdevname(bh->b_bdev, b), 184 (unsigned long long)bh->b_blocknr); 185 } 186 187 static void ext4_end_bio(struct bio *bio, int error) 188 { 189 ext4_io_end_t *io_end = bio->bi_private; 190 struct workqueue_struct *wq; 191 struct inode *inode; 192 unsigned long flags; 193 int i; 194 sector_t bi_sector = bio->bi_sector; 195 196 BUG_ON(!io_end); 197 bio->bi_private = NULL; 198 bio->bi_end_io = NULL; 199 if (test_bit(BIO_UPTODATE, &bio->bi_flags)) 200 error = 0; 201 bio_put(bio); 202 203 for (i = 0; i < io_end->num_io_pages; i++) { 204 struct page *page = io_end->pages[i]->p_page; 205 struct buffer_head *bh, *head; 206 int partial_write = 0; 207 208 head = page_buffers(page); 209 if (error) 210 SetPageError(page); 211 BUG_ON(!head); 212 if (head->b_size != PAGE_CACHE_SIZE) { 213 loff_t offset; 214 loff_t io_end_offset = io_end->offset + io_end->size; 215 216 offset = (sector_t) page->index << PAGE_CACHE_SHIFT; 217 bh = head; 218 do { 219 if ((offset >= io_end->offset) && 220 (offset+bh->b_size <= io_end_offset)) { 221 if (error) 222 buffer_io_error(bh); 223 224 } 225 if (buffer_delay(bh)) 226 partial_write = 1; 227 else if (!buffer_mapped(bh)) 228 clear_buffer_dirty(bh); 229 else if (buffer_dirty(bh)) 230 partial_write = 1; 231 offset += bh->b_size; 232 bh = bh->b_this_page; 233 } while (bh != head); 234 } 235 236 /* 237 * If this is a partial write which happened to make 238 * all buffers uptodate then we can optimize away a 239 * bogus readpage() for the next read(). Here we 240 * 'discover' whether the page went uptodate as a 241 * result of this (potentially partial) write. 242 */ 243 if (!partial_write) 244 SetPageUptodate(page); 245 246 put_io_page(io_end->pages[i]); 247 } 248 io_end->num_io_pages = 0; 249 inode = io_end->inode; 250 251 if (error) { 252 io_end->flag |= EXT4_IO_END_ERROR; 253 ext4_warning(inode->i_sb, "I/O error writing to inode %lu " 254 "(offset %llu size %ld starting block %llu)", 255 inode->i_ino, 256 (unsigned long long) io_end->offset, 257 (long) io_end->size, 258 (unsigned long long) 259 bi_sector >> (inode->i_blkbits - 9)); 260 } 261 262 /* Add the io_end to per-inode completed io list*/ 263 spin_lock_irqsave(&EXT4_I(inode)->i_completed_io_lock, flags); 264 list_add_tail(&io_end->list, &EXT4_I(inode)->i_completed_io_list); 265 spin_unlock_irqrestore(&EXT4_I(inode)->i_completed_io_lock, flags); 266 267 wq = EXT4_SB(inode->i_sb)->dio_unwritten_wq; 268 /* queue the work to convert unwritten extents to written */ 269 queue_work(wq, &io_end->work); 270 } 271 272 void ext4_io_submit(struct ext4_io_submit *io) 273 { 274 struct bio *bio = io->io_bio; 275 276 if (bio) { 277 bio_get(io->io_bio); 278 submit_bio(io->io_op, io->io_bio); 279 BUG_ON(bio_flagged(io->io_bio, BIO_EOPNOTSUPP)); 280 bio_put(io->io_bio); 281 } 282 io->io_bio = 0; 283 io->io_op = 0; 284 io->io_end = 0; 285 } 286 287 static int io_submit_init(struct ext4_io_submit *io, 288 struct inode *inode, 289 struct writeback_control *wbc, 290 struct buffer_head *bh) 291 { 292 ext4_io_end_t *io_end; 293 struct page *page = bh->b_page; 294 int nvecs = bio_get_nr_vecs(bh->b_bdev); 295 struct bio *bio; 296 297 io_end = ext4_init_io_end(inode, GFP_NOFS); 298 if (!io_end) 299 return -ENOMEM; 300 do { 301 bio = bio_alloc(GFP_NOIO, nvecs); 302 nvecs >>= 1; 303 } while (bio == NULL); 304 305 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 ? 314 WRITE_SYNC_PLUG : WRITE); 315 io->io_next_block = bh->b_blocknr; 316 return 0; 317 } 318 319 static int io_submit_add_bh(struct ext4_io_submit *io, 320 struct ext4_io_page *io_page, 321 struct inode *inode, 322 struct writeback_control *wbc, 323 struct buffer_head *bh) 324 { 325 ext4_io_end_t *io_end; 326 int ret; 327 328 if (buffer_new(bh)) { 329 clear_buffer_new(bh); 330 unmap_underlying_metadata(bh->b_bdev, bh->b_blocknr); 331 } 332 333 if (!buffer_mapped(bh) || buffer_delay(bh)) { 334 if (!buffer_mapped(bh)) 335 clear_buffer_dirty(bh); 336 if (io->io_bio) 337 ext4_io_submit(io); 338 return 0; 339 } 340 341 if (io->io_bio && bh->b_blocknr != io->io_next_block) { 342 submit_and_retry: 343 ext4_io_submit(io); 344 } 345 if (io->io_bio == NULL) { 346 ret = io_submit_init(io, inode, wbc, bh); 347 if (ret) 348 return ret; 349 } 350 io_end = io->io_end; 351 if ((io_end->num_io_pages >= MAX_IO_PAGES) && 352 (io_end->pages[io_end->num_io_pages-1] != io_page)) 353 goto submit_and_retry; 354 if (buffer_uninit(bh)) 355 io->io_end->flag |= EXT4_IO_END_UNWRITTEN; 356 io->io_end->size += bh->b_size; 357 io->io_next_block++; 358 ret = bio_add_page(io->io_bio, bh->b_page, bh->b_size, bh_offset(bh)); 359 if (ret != bh->b_size) 360 goto submit_and_retry; 361 if ((io_end->num_io_pages == 0) || 362 (io_end->pages[io_end->num_io_pages-1] != io_page)) { 363 io_end->pages[io_end->num_io_pages++] = io_page; 364 atomic_inc(&io_page->p_count); 365 } 366 return 0; 367 } 368 369 int ext4_bio_write_page(struct ext4_io_submit *io, 370 struct page *page, 371 int len, 372 struct writeback_control *wbc) 373 { 374 struct inode *inode = page->mapping->host; 375 unsigned block_start, block_end, blocksize; 376 struct ext4_io_page *io_page; 377 struct buffer_head *bh, *head; 378 int ret = 0; 379 380 blocksize = 1 << inode->i_blkbits; 381 382 BUG_ON(!PageLocked(page)); 383 BUG_ON(PageWriteback(page)); 384 set_page_writeback(page); 385 ClearPageError(page); 386 387 io_page = kmem_cache_alloc(io_page_cachep, GFP_NOFS); 388 if (!io_page) { 389 set_page_dirty(page); 390 unlock_page(page); 391 return -ENOMEM; 392 } 393 io_page->p_page = page; 394 atomic_set(&io_page->p_count, 1); 395 get_page(page); 396 397 for (bh = head = page_buffers(page), block_start = 0; 398 bh != head || !block_start; 399 block_start = block_end, bh = bh->b_this_page) { 400 401 block_end = block_start + blocksize; 402 if (block_start >= len) { 403 clear_buffer_dirty(bh); 404 set_buffer_uptodate(bh); 405 continue; 406 } 407 clear_buffer_dirty(bh); 408 ret = io_submit_add_bh(io, io_page, inode, wbc, bh); 409 if (ret) { 410 /* 411 * We only get here on ENOMEM. Not much else 412 * we can do but mark the page as dirty, and 413 * better luck next time. 414 */ 415 set_page_dirty(page); 416 break; 417 } 418 } 419 unlock_page(page); 420 /* 421 * If the page was truncated before we could do the writeback, 422 * or we had a memory allocation error while trying to write 423 * the first buffer head, we won't have submitted any pages for 424 * I/O. In that case we need to make sure we've cleared the 425 * PageWriteback bit from the page to prevent the system from 426 * wedging later on. 427 */ 428 put_io_page(io_page); 429 return ret; 430 } 431