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
27 #include "ext4_jbd2.h"
28 #include "xattr.h"
29 #include "acl.h"
30 #include "ext4_extents.h"
31
32 static struct kmem_cache *io_page_cachep, *io_end_cachep;
33
ext4_init_pageio(void)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
ext4_exit_pageio(void)47 void ext4_exit_pageio(void)
48 {
49 kmem_cache_destroy(io_end_cachep);
50 kmem_cache_destroy(io_page_cachep);
51 }
52
ext4_ioend_wait(struct inode * inode)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
put_io_page(struct ext4_io_page * io_page)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
ext4_free_io_end(ext4_io_end_t * io)69 void ext4_free_io_end(ext4_io_end_t *io)
70 {
71 int i;
72
73 BUG_ON(!io);
74 if (io->page)
75 put_page(io->page);
76 for (i = 0; i < io->num_io_pages; i++)
77 put_io_page(io->pages[i]);
78 io->num_io_pages = 0;
79 if (atomic_dec_and_test(&EXT4_I(io->inode)->i_ioend_count))
80 wake_up_all(ext4_ioend_wq(io->inode));
81 kmem_cache_free(io_end_cachep, io);
82 }
83
84 /*
85 * check a range of space and convert unwritten extents to written.
86 *
87 * Called with inode->i_mutex; we depend on this when we manipulate
88 * io->flag, since we could otherwise race with ext4_flush_completed_IO()
89 */
ext4_end_io_nolock(ext4_io_end_t * io)90 int ext4_end_io_nolock(ext4_io_end_t *io)
91 {
92 struct inode *inode = io->inode;
93 loff_t offset = io->offset;
94 ssize_t size = io->size;
95 int ret = 0;
96
97 ext4_debug("ext4_end_io_nolock: io 0x%p from inode %lu,list->next 0x%p,"
98 "list->prev 0x%p\n",
99 io, inode->i_ino, io->list.next, io->list.prev);
100
101 ret = ext4_convert_unwritten_extents(inode, offset, size);
102 if (ret < 0) {
103 ext4_msg(inode->i_sb, KERN_EMERG,
104 "failed to convert unwritten extents to written "
105 "extents -- potential data loss! "
106 "(inode %lu, offset %llu, size %zd, error %d)",
107 inode->i_ino, offset, size, ret);
108 }
109
110 if (io->iocb)
111 aio_complete(io->iocb, io->result, 0);
112
113 if (io->flag & EXT4_IO_END_DIRECT)
114 inode_dio_done(inode);
115 /* Wake up anyone waiting on unwritten extent conversion */
116 if (atomic_dec_and_test(&EXT4_I(inode)->i_aiodio_unwritten))
117 wake_up_all(ext4_ioend_wq(io->inode));
118 return ret;
119 }
120
121 /*
122 * work on completed aio dio IO, to convert unwritten extents to extents
123 */
ext4_end_io_work(struct work_struct * work)124 static void ext4_end_io_work(struct work_struct *work)
125 {
126 ext4_io_end_t *io = container_of(work, ext4_io_end_t, work);
127 struct inode *inode = io->inode;
128 struct ext4_inode_info *ei = EXT4_I(inode);
129 unsigned long flags;
130
131 spin_lock_irqsave(&ei->i_completed_io_lock, flags);
132 if (io->flag & EXT4_IO_END_IN_FSYNC)
133 goto requeue;
134 if (list_empty(&io->list)) {
135 spin_unlock_irqrestore(&ei->i_completed_io_lock, flags);
136 goto free;
137 }
138
139 if (!mutex_trylock(&inode->i_mutex)) {
140 bool was_queued;
141 requeue:
142 was_queued = !!(io->flag & EXT4_IO_END_QUEUED);
143 io->flag |= EXT4_IO_END_QUEUED;
144 spin_unlock_irqrestore(&ei->i_completed_io_lock, flags);
145 /*
146 * Requeue the work instead of waiting so that the work
147 * items queued after this can be processed.
148 */
149 queue_work(EXT4_SB(inode->i_sb)->dio_unwritten_wq, &io->work);
150 /*
151 * To prevent the ext4-dio-unwritten thread from keeping
152 * requeueing end_io requests and occupying cpu for too long,
153 * yield the cpu if it sees an end_io request that has already
154 * been requeued.
155 */
156 if (was_queued)
157 yield();
158 return;
159 }
160 list_del_init(&io->list);
161 spin_unlock_irqrestore(&ei->i_completed_io_lock, flags);
162 (void) ext4_end_io_nolock(io);
163 mutex_unlock(&inode->i_mutex);
164 free:
165 ext4_free_io_end(io);
166 }
167
ext4_init_io_end(struct inode * inode,gfp_t flags)168 ext4_io_end_t *ext4_init_io_end(struct inode *inode, gfp_t flags)
169 {
170 ext4_io_end_t *io = kmem_cache_zalloc(io_end_cachep, flags);
171 if (io) {
172 atomic_inc(&EXT4_I(inode)->i_ioend_count);
173 io->inode = inode;
174 INIT_WORK(&io->work, ext4_end_io_work);
175 INIT_LIST_HEAD(&io->list);
176 }
177 return io;
178 }
179
180 /*
181 * Print an buffer I/O error compatible with the fs/buffer.c. This
182 * provides compatibility with dmesg scrapers that look for a specific
183 * buffer I/O error message. We really need a unified error reporting
184 * structure to userspace ala Digital Unix's uerf system, but it's
185 * probably not going to happen in my lifetime, due to LKML politics...
186 */
buffer_io_error(struct buffer_head * bh)187 static void buffer_io_error(struct buffer_head *bh)
188 {
189 char b[BDEVNAME_SIZE];
190 printk(KERN_ERR "Buffer I/O error on device %s, logical block %llu\n",
191 bdevname(bh->b_bdev, b),
192 (unsigned long long)bh->b_blocknr);
193 }
194
ext4_end_bio(struct bio * bio,int error)195 static void ext4_end_bio(struct bio *bio, int error)
196 {
197 ext4_io_end_t *io_end = bio->bi_private;
198 struct workqueue_struct *wq;
199 struct inode *inode;
200 unsigned long flags;
201 int i;
202 sector_t bi_sector = bio->bi_sector;
203
204 BUG_ON(!io_end);
205 bio->bi_private = NULL;
206 bio->bi_end_io = NULL;
207 if (test_bit(BIO_UPTODATE, &bio->bi_flags))
208 error = 0;
209 bio_put(bio);
210
211 for (i = 0; i < io_end->num_io_pages; i++) {
212 struct page *page = io_end->pages[i]->p_page;
213 struct buffer_head *bh, *head;
214 loff_t offset;
215 loff_t io_end_offset;
216
217 if (error) {
218 SetPageError(page);
219 set_bit(AS_EIO, &page->mapping->flags);
220 head = page_buffers(page);
221 BUG_ON(!head);
222
223 io_end_offset = io_end->offset + io_end->size;
224
225 offset = (sector_t) page->index << PAGE_CACHE_SHIFT;
226 bh = head;
227 do {
228 if ((offset >= io_end->offset) &&
229 (offset+bh->b_size <= io_end_offset))
230 buffer_io_error(bh);
231
232 offset += bh->b_size;
233 bh = bh->b_this_page;
234 } while (bh != head);
235 }
236
237 put_io_page(io_end->pages[i]);
238 }
239 io_end->num_io_pages = 0;
240 inode = io_end->inode;
241
242 if (error) {
243 io_end->flag |= EXT4_IO_END_ERROR;
244 ext4_warning(inode->i_sb, "I/O error writing to inode %lu "
245 "(offset %llu size %ld starting block %llu)",
246 inode->i_ino,
247 (unsigned long long) io_end->offset,
248 (long) io_end->size,
249 (unsigned long long)
250 bi_sector >> (inode->i_blkbits - 9));
251 }
252
253 if (!(io_end->flag & EXT4_IO_END_UNWRITTEN)) {
254 ext4_free_io_end(io_end);
255 return;
256 }
257
258 /* Add the io_end to per-inode completed io list*/
259 spin_lock_irqsave(&EXT4_I(inode)->i_completed_io_lock, flags);
260 list_add_tail(&io_end->list, &EXT4_I(inode)->i_completed_io_list);
261 spin_unlock_irqrestore(&EXT4_I(inode)->i_completed_io_lock, flags);
262
263 wq = EXT4_SB(inode->i_sb)->dio_unwritten_wq;
264 /* queue the work to convert unwritten extents to written */
265 queue_work(wq, &io_end->work);
266 }
267
ext4_io_submit(struct ext4_io_submit * io)268 void ext4_io_submit(struct ext4_io_submit *io)
269 {
270 struct bio *bio = io->io_bio;
271
272 if (bio) {
273 bio_get(io->io_bio);
274 submit_bio(io->io_op, io->io_bio);
275 BUG_ON(bio_flagged(io->io_bio, BIO_EOPNOTSUPP));
276 bio_put(io->io_bio);
277 }
278 io->io_bio = NULL;
279 io->io_op = 0;
280 io->io_end = NULL;
281 }
282
io_submit_init(struct ext4_io_submit * io,struct inode * inode,struct writeback_control * wbc,struct buffer_head * bh)283 static int io_submit_init(struct ext4_io_submit *io,
284 struct inode *inode,
285 struct writeback_control *wbc,
286 struct buffer_head *bh)
287 {
288 ext4_io_end_t *io_end;
289 struct page *page = bh->b_page;
290 int nvecs = bio_get_nr_vecs(bh->b_bdev);
291 struct bio *bio;
292
293 io_end = ext4_init_io_end(inode, GFP_NOFS);
294 if (!io_end)
295 return -ENOMEM;
296 bio = bio_alloc(GFP_NOIO, min(nvecs, BIO_MAX_PAGES));
297 bio->bi_sector = bh->b_blocknr * (bh->b_size >> 9);
298 bio->bi_bdev = bh->b_bdev;
299 bio->bi_private = io->io_end = io_end;
300 bio->bi_end_io = ext4_end_bio;
301
302 io_end->offset = (page->index << PAGE_CACHE_SHIFT) + bh_offset(bh);
303
304 io->io_bio = bio;
305 io->io_op = (wbc->sync_mode == WB_SYNC_ALL ? WRITE_SYNC : WRITE);
306 io->io_next_block = bh->b_blocknr;
307 return 0;
308 }
309
io_submit_add_bh(struct ext4_io_submit * io,struct ext4_io_page * io_page,struct inode * inode,struct writeback_control * wbc,struct buffer_head * bh)310 static int io_submit_add_bh(struct ext4_io_submit *io,
311 struct ext4_io_page *io_page,
312 struct inode *inode,
313 struct writeback_control *wbc,
314 struct buffer_head *bh)
315 {
316 ext4_io_end_t *io_end;
317 int ret;
318
319 if (buffer_new(bh)) {
320 clear_buffer_new(bh);
321 unmap_underlying_metadata(bh->b_bdev, bh->b_blocknr);
322 }
323
324 if (!buffer_mapped(bh) || buffer_delay(bh)) {
325 if (!buffer_mapped(bh))
326 clear_buffer_dirty(bh);
327 if (io->io_bio)
328 ext4_io_submit(io);
329 return 0;
330 }
331
332 if (io->io_bio && bh->b_blocknr != io->io_next_block) {
333 submit_and_retry:
334 ext4_io_submit(io);
335 }
336 if (io->io_bio == NULL) {
337 ret = io_submit_init(io, inode, wbc, bh);
338 if (ret)
339 return ret;
340 }
341 io_end = io->io_end;
342 if ((io_end->num_io_pages >= MAX_IO_PAGES) &&
343 (io_end->pages[io_end->num_io_pages-1] != io_page))
344 goto submit_and_retry;
345 if (buffer_uninit(bh))
346 ext4_set_io_unwritten_flag(inode, io_end);
347 io->io_end->size += bh->b_size;
348 io->io_next_block++;
349 ret = bio_add_page(io->io_bio, bh->b_page, bh->b_size, bh_offset(bh));
350 if (ret != bh->b_size)
351 goto submit_and_retry;
352 if ((io_end->num_io_pages == 0) ||
353 (io_end->pages[io_end->num_io_pages-1] != io_page)) {
354 io_end->pages[io_end->num_io_pages++] = io_page;
355 atomic_inc(&io_page->p_count);
356 }
357 return 0;
358 }
359
ext4_bio_write_page(struct ext4_io_submit * io,struct page * page,int len,struct writeback_control * wbc)360 int ext4_bio_write_page(struct ext4_io_submit *io,
361 struct page *page,
362 int len,
363 struct writeback_control *wbc)
364 {
365 struct inode *inode = page->mapping->host;
366 unsigned block_start, block_end, blocksize;
367 struct ext4_io_page *io_page;
368 struct buffer_head *bh, *head;
369 int ret = 0;
370
371 blocksize = 1 << inode->i_blkbits;
372
373 BUG_ON(!PageLocked(page));
374 BUG_ON(PageWriteback(page));
375
376 io_page = kmem_cache_alloc(io_page_cachep, GFP_NOFS);
377 if (!io_page) {
378 set_page_dirty(page);
379 unlock_page(page);
380 return -ENOMEM;
381 }
382 io_page->p_page = page;
383 atomic_set(&io_page->p_count, 1);
384 get_page(page);
385 set_page_writeback(page);
386 ClearPageError(page);
387
388 for (bh = head = page_buffers(page), block_start = 0;
389 bh != head || !block_start;
390 block_start = block_end, bh = bh->b_this_page) {
391
392 block_end = block_start + blocksize;
393 if (block_start >= len) {
394 /*
395 * Comments copied from block_write_full_page_endio:
396 *
397 * The page straddles i_size. It must be zeroed out on
398 * each and every writepage invocation because it may
399 * be mmapped. "A file is mapped in multiples of the
400 * page size. For a file that is not a multiple of
401 * the page size, the remaining memory is zeroed when
402 * mapped, and writes to that region are not written
403 * out to the file."
404 */
405 zero_user_segment(page, block_start, block_end);
406 clear_buffer_dirty(bh);
407 set_buffer_uptodate(bh);
408 continue;
409 }
410 clear_buffer_dirty(bh);
411 ret = io_submit_add_bh(io, io_page, inode, wbc, bh);
412 if (ret) {
413 /*
414 * We only get here on ENOMEM. Not much else
415 * we can do but mark the page as dirty, and
416 * better luck next time.
417 */
418 set_page_dirty(page);
419 break;
420 }
421 }
422 unlock_page(page);
423 /*
424 * If the page was truncated before we could do the writeback,
425 * or we had a memory allocation error while trying to write
426 * the first buffer head, we won't have submitted any pages for
427 * I/O. In that case we need to make sure we've cleared the
428 * PageWriteback bit from the page to prevent the system from
429 * wedging later on.
430 */
431 put_io_page(io_page);
432 return ret;
433 }
434