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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
33static struct kmem_cache *io_page_cachep, *io_end_cachep;
34
35int __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
48void ext4_exit_pageio(void)
49{
50 kmem_cache_destroy(io_end_cachep);
51 kmem_cache_destroy(io_page_cachep);
52}
53
54void 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
61static 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
70void 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 */
91int 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 */
137static 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
176ext4_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 */
195static 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
203static 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
276void 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
291static 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
318static 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) {
341submit_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
370int 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}
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
32static struct kmem_cache *io_page_cachep, *io_end_cachep;
33
34int __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
47void ext4_exit_pageio(void)
48{
49 kmem_cache_destroy(io_end_cachep);
50 kmem_cache_destroy(io_page_cachep);
51}
52
53void 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
60static 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
69void 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 */
90int 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 */
124static 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;
141requeue:
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);
164free:
165 ext4_free_io_end(io);
166}
167
168ext4_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 */
187static 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
195static 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
268void 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
283static 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
310static 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) {
333submit_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
360int 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}