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