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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/highuid.h>
12#include <linux/pagemap.h>
13#include <linux/quotaops.h>
14#include <linux/string.h>
15#include <linux/buffer_head.h>
16#include <linux/writeback.h>
17#include <linux/pagevec.h>
18#include <linux/mpage.h>
19#include <linux/namei.h>
20#include <linux/uio.h>
21#include <linux/bio.h>
22#include <linux/workqueue.h>
23#include <linux/kernel.h>
24#include <linux/slab.h>
25#include <linux/mm.h>
26#include <linux/backing-dev.h>
27
28#include "ext4_jbd2.h"
29#include "xattr.h"
30#include "acl.h"
31
32static struct kmem_cache *io_end_cachep;
33
34int __init ext4_init_pageio(void)
35{
36 io_end_cachep = KMEM_CACHE(ext4_io_end, SLAB_RECLAIM_ACCOUNT);
37 if (io_end_cachep == NULL)
38 return -ENOMEM;
39 return 0;
40}
41
42void ext4_exit_pageio(void)
43{
44 kmem_cache_destroy(io_end_cachep);
45}
46
47/*
48 * Print an buffer I/O error compatible with the fs/buffer.c. This
49 * provides compatibility with dmesg scrapers that look for a specific
50 * buffer I/O error message. We really need a unified error reporting
51 * structure to userspace ala Digital Unix's uerf system, but it's
52 * probably not going to happen in my lifetime, due to LKML politics...
53 */
54static void buffer_io_error(struct buffer_head *bh)
55{
56 printk_ratelimited(KERN_ERR "Buffer I/O error on device %pg, logical block %llu\n",
57 bh->b_bdev,
58 (unsigned long long)bh->b_blocknr);
59}
60
61static void ext4_finish_bio(struct bio *bio)
62{
63 int i;
64 struct bio_vec *bvec;
65
66 bio_for_each_segment_all(bvec, bio, i) {
67 struct page *page = bvec->bv_page;
68#ifdef CONFIG_EXT4_FS_ENCRYPTION
69 struct page *data_page = NULL;
70 struct ext4_crypto_ctx *ctx = NULL;
71#endif
72 struct buffer_head *bh, *head;
73 unsigned bio_start = bvec->bv_offset;
74 unsigned bio_end = bio_start + bvec->bv_len;
75 unsigned under_io = 0;
76 unsigned long flags;
77
78 if (!page)
79 continue;
80
81#ifdef CONFIG_EXT4_FS_ENCRYPTION
82 if (!page->mapping) {
83 /* The bounce data pages are unmapped. */
84 data_page = page;
85 ctx = (struct ext4_crypto_ctx *)page_private(data_page);
86 page = ctx->w.control_page;
87 }
88#endif
89
90 if (bio->bi_error) {
91 SetPageError(page);
92 set_bit(AS_EIO, &page->mapping->flags);
93 }
94 bh = head = page_buffers(page);
95 /*
96 * We check all buffers in the page under BH_Uptodate_Lock
97 * to avoid races with other end io clearing async_write flags
98 */
99 local_irq_save(flags);
100 bit_spin_lock(BH_Uptodate_Lock, &head->b_state);
101 do {
102 if (bh_offset(bh) < bio_start ||
103 bh_offset(bh) + bh->b_size > bio_end) {
104 if (buffer_async_write(bh))
105 under_io++;
106 continue;
107 }
108 clear_buffer_async_write(bh);
109 if (bio->bi_error)
110 buffer_io_error(bh);
111 } while ((bh = bh->b_this_page) != head);
112 bit_spin_unlock(BH_Uptodate_Lock, &head->b_state);
113 local_irq_restore(flags);
114 if (!under_io) {
115#ifdef CONFIG_EXT4_FS_ENCRYPTION
116 if (ctx)
117 ext4_restore_control_page(data_page);
118#endif
119 end_page_writeback(page);
120 }
121 }
122}
123
124static void ext4_release_io_end(ext4_io_end_t *io_end)
125{
126 struct bio *bio, *next_bio;
127
128 BUG_ON(!list_empty(&io_end->list));
129 BUG_ON(io_end->flag & EXT4_IO_END_UNWRITTEN);
130 WARN_ON(io_end->handle);
131
132 for (bio = io_end->bio; bio; bio = next_bio) {
133 next_bio = bio->bi_private;
134 ext4_finish_bio(bio);
135 bio_put(bio);
136 }
137 kmem_cache_free(io_end_cachep, io_end);
138}
139
140/*
141 * Check a range of space and convert unwritten extents to written. Note that
142 * we are protected from truncate touching same part of extent tree by the
143 * fact that truncate code waits for all DIO to finish (thus exclusion from
144 * direct IO is achieved) and also waits for PageWriteback bits. Thus we
145 * cannot get to ext4_ext_truncate() before all IOs overlapping that range are
146 * completed (happens from ext4_free_ioend()).
147 */
148static int ext4_end_io(ext4_io_end_t *io)
149{
150 struct inode *inode = io->inode;
151 loff_t offset = io->offset;
152 ssize_t size = io->size;
153 handle_t *handle = io->handle;
154 int ret = 0;
155
156 ext4_debug("ext4_end_io_nolock: io 0x%p from inode %lu,list->next 0x%p,"
157 "list->prev 0x%p\n",
158 io, inode->i_ino, io->list.next, io->list.prev);
159
160 io->handle = NULL; /* Following call will use up the handle */
161 ret = ext4_convert_unwritten_extents(handle, inode, offset, size);
162 if (ret < 0) {
163 ext4_msg(inode->i_sb, KERN_EMERG,
164 "failed to convert unwritten extents to written "
165 "extents -- potential data loss! "
166 "(inode %lu, offset %llu, size %zd, error %d)",
167 inode->i_ino, offset, size, ret);
168 }
169 ext4_clear_io_unwritten_flag(io);
170 ext4_release_io_end(io);
171 return ret;
172}
173
174static void dump_completed_IO(struct inode *inode, struct list_head *head)
175{
176#ifdef EXT4FS_DEBUG
177 struct list_head *cur, *before, *after;
178 ext4_io_end_t *io, *io0, *io1;
179
180 if (list_empty(head))
181 return;
182
183 ext4_debug("Dump inode %lu completed io list\n", inode->i_ino);
184 list_for_each_entry(io, head, list) {
185 cur = &io->list;
186 before = cur->prev;
187 io0 = container_of(before, ext4_io_end_t, list);
188 after = cur->next;
189 io1 = container_of(after, ext4_io_end_t, list);
190
191 ext4_debug("io 0x%p from inode %lu,prev 0x%p,next 0x%p\n",
192 io, inode->i_ino, io0, io1);
193 }
194#endif
195}
196
197/* Add the io_end to per-inode completed end_io list. */
198static void ext4_add_complete_io(ext4_io_end_t *io_end)
199{
200 struct ext4_inode_info *ei = EXT4_I(io_end->inode);
201 struct ext4_sb_info *sbi = EXT4_SB(io_end->inode->i_sb);
202 struct workqueue_struct *wq;
203 unsigned long flags;
204
205 /* Only reserved conversions from writeback should enter here */
206 WARN_ON(!(io_end->flag & EXT4_IO_END_UNWRITTEN));
207 WARN_ON(!io_end->handle && sbi->s_journal);
208 spin_lock_irqsave(&ei->i_completed_io_lock, flags);
209 wq = sbi->rsv_conversion_wq;
210 if (list_empty(&ei->i_rsv_conversion_list))
211 queue_work(wq, &ei->i_rsv_conversion_work);
212 list_add_tail(&io_end->list, &ei->i_rsv_conversion_list);
213 spin_unlock_irqrestore(&ei->i_completed_io_lock, flags);
214}
215
216static int ext4_do_flush_completed_IO(struct inode *inode,
217 struct list_head *head)
218{
219 ext4_io_end_t *io;
220 struct list_head unwritten;
221 unsigned long flags;
222 struct ext4_inode_info *ei = EXT4_I(inode);
223 int err, ret = 0;
224
225 spin_lock_irqsave(&ei->i_completed_io_lock, flags);
226 dump_completed_IO(inode, head);
227 list_replace_init(head, &unwritten);
228 spin_unlock_irqrestore(&ei->i_completed_io_lock, flags);
229
230 while (!list_empty(&unwritten)) {
231 io = list_entry(unwritten.next, ext4_io_end_t, list);
232 BUG_ON(!(io->flag & EXT4_IO_END_UNWRITTEN));
233 list_del_init(&io->list);
234
235 err = ext4_end_io(io);
236 if (unlikely(!ret && err))
237 ret = err;
238 }
239 return ret;
240}
241
242/*
243 * work on completed IO, to convert unwritten extents to extents
244 */
245void ext4_end_io_rsv_work(struct work_struct *work)
246{
247 struct ext4_inode_info *ei = container_of(work, struct ext4_inode_info,
248 i_rsv_conversion_work);
249 ext4_do_flush_completed_IO(&ei->vfs_inode, &ei->i_rsv_conversion_list);
250}
251
252ext4_io_end_t *ext4_init_io_end(struct inode *inode, gfp_t flags)
253{
254 ext4_io_end_t *io = kmem_cache_zalloc(io_end_cachep, flags);
255 if (io) {
256 io->inode = inode;
257 INIT_LIST_HEAD(&io->list);
258 atomic_set(&io->count, 1);
259 }
260 return io;
261}
262
263void ext4_put_io_end_defer(ext4_io_end_t *io_end)
264{
265 if (atomic_dec_and_test(&io_end->count)) {
266 if (!(io_end->flag & EXT4_IO_END_UNWRITTEN) || !io_end->size) {
267 ext4_release_io_end(io_end);
268 return;
269 }
270 ext4_add_complete_io(io_end);
271 }
272}
273
274int ext4_put_io_end(ext4_io_end_t *io_end)
275{
276 int err = 0;
277
278 if (atomic_dec_and_test(&io_end->count)) {
279 if (io_end->flag & EXT4_IO_END_UNWRITTEN) {
280 err = ext4_convert_unwritten_extents(io_end->handle,
281 io_end->inode, io_end->offset,
282 io_end->size);
283 io_end->handle = NULL;
284 ext4_clear_io_unwritten_flag(io_end);
285 }
286 ext4_release_io_end(io_end);
287 }
288 return err;
289}
290
291ext4_io_end_t *ext4_get_io_end(ext4_io_end_t *io_end)
292{
293 atomic_inc(&io_end->count);
294 return io_end;
295}
296
297/* BIO completion function for page writeback */
298static void ext4_end_bio(struct bio *bio)
299{
300 ext4_io_end_t *io_end = bio->bi_private;
301 sector_t bi_sector = bio->bi_iter.bi_sector;
302
303 BUG_ON(!io_end);
304 bio->bi_end_io = NULL;
305
306 if (bio->bi_error) {
307 struct inode *inode = io_end->inode;
308
309 ext4_warning(inode->i_sb, "I/O error %d writing to inode %lu "
310 "(offset %llu size %ld starting block %llu)",
311 bio->bi_error, inode->i_ino,
312 (unsigned long long) io_end->offset,
313 (long) io_end->size,
314 (unsigned long long)
315 bi_sector >> (inode->i_blkbits - 9));
316 mapping_set_error(inode->i_mapping, bio->bi_error);
317 }
318
319 if (io_end->flag & EXT4_IO_END_UNWRITTEN) {
320 /*
321 * Link bio into list hanging from io_end. We have to do it
322 * atomically as bio completions can be racing against each
323 * other.
324 */
325 bio->bi_private = xchg(&io_end->bio, bio);
326 ext4_put_io_end_defer(io_end);
327 } else {
328 /*
329 * Drop io_end reference early. Inode can get freed once
330 * we finish the bio.
331 */
332 ext4_put_io_end_defer(io_end);
333 ext4_finish_bio(bio);
334 bio_put(bio);
335 }
336}
337
338void ext4_io_submit(struct ext4_io_submit *io)
339{
340 struct bio *bio = io->io_bio;
341
342 if (bio) {
343 int io_op = io->io_wbc->sync_mode == WB_SYNC_ALL ?
344 WRITE_SYNC : WRITE;
345 bio_get(io->io_bio);
346 submit_bio(io_op, io->io_bio);
347 bio_put(io->io_bio);
348 }
349 io->io_bio = NULL;
350}
351
352void ext4_io_submit_init(struct ext4_io_submit *io,
353 struct writeback_control *wbc)
354{
355 io->io_wbc = wbc;
356 io->io_bio = NULL;
357 io->io_end = NULL;
358}
359
360static int io_submit_init_bio(struct ext4_io_submit *io,
361 struct buffer_head *bh)
362{
363 struct bio *bio;
364
365 bio = bio_alloc(GFP_NOIO, BIO_MAX_PAGES);
366 if (!bio)
367 return -ENOMEM;
368 wbc_init_bio(io->io_wbc, bio);
369 bio->bi_iter.bi_sector = bh->b_blocknr * (bh->b_size >> 9);
370 bio->bi_bdev = bh->b_bdev;
371 bio->bi_end_io = ext4_end_bio;
372 bio->bi_private = ext4_get_io_end(io->io_end);
373 io->io_bio = bio;
374 io->io_next_block = bh->b_blocknr;
375 return 0;
376}
377
378static int io_submit_add_bh(struct ext4_io_submit *io,
379 struct inode *inode,
380 struct page *page,
381 struct buffer_head *bh)
382{
383 int ret;
384
385 if (io->io_bio && bh->b_blocknr != io->io_next_block) {
386submit_and_retry:
387 ext4_io_submit(io);
388 }
389 if (io->io_bio == NULL) {
390 ret = io_submit_init_bio(io, bh);
391 if (ret)
392 return ret;
393 }
394 ret = bio_add_page(io->io_bio, page, bh->b_size, bh_offset(bh));
395 if (ret != bh->b_size)
396 goto submit_and_retry;
397 wbc_account_io(io->io_wbc, page, bh->b_size);
398 io->io_next_block++;
399 return 0;
400}
401
402int ext4_bio_write_page(struct ext4_io_submit *io,
403 struct page *page,
404 int len,
405 struct writeback_control *wbc,
406 bool keep_towrite)
407{
408 struct page *data_page = NULL;
409 struct inode *inode = page->mapping->host;
410 unsigned block_start, blocksize;
411 struct buffer_head *bh, *head;
412 int ret = 0;
413 int nr_submitted = 0;
414 int nr_to_submit = 0;
415
416 blocksize = 1 << inode->i_blkbits;
417
418 BUG_ON(!PageLocked(page));
419 BUG_ON(PageWriteback(page));
420
421 if (keep_towrite)
422 set_page_writeback_keepwrite(page);
423 else
424 set_page_writeback(page);
425 ClearPageError(page);
426
427 /*
428 * Comments copied from block_write_full_page:
429 *
430 * The page straddles i_size. It must be zeroed out on each and every
431 * writepage invocation because it may be mmapped. "A file is mapped
432 * in multiples of the page size. For a file that is not a multiple of
433 * the page size, the remaining memory is zeroed when mapped, and
434 * writes to that region are not written out to the file."
435 */
436 if (len < PAGE_SIZE)
437 zero_user_segment(page, len, PAGE_SIZE);
438 /*
439 * In the first loop we prepare and mark buffers to submit. We have to
440 * mark all buffers in the page before submitting so that
441 * end_page_writeback() cannot be called from ext4_bio_end_io() when IO
442 * on the first buffer finishes and we are still working on submitting
443 * the second buffer.
444 */
445 bh = head = page_buffers(page);
446 do {
447 block_start = bh_offset(bh);
448 if (block_start >= len) {
449 clear_buffer_dirty(bh);
450 set_buffer_uptodate(bh);
451 continue;
452 }
453 if (!buffer_dirty(bh) || buffer_delay(bh) ||
454 !buffer_mapped(bh) || buffer_unwritten(bh)) {
455 /* A hole? We can safely clear the dirty bit */
456 if (!buffer_mapped(bh))
457 clear_buffer_dirty(bh);
458 if (io->io_bio)
459 ext4_io_submit(io);
460 continue;
461 }
462 if (buffer_new(bh)) {
463 clear_buffer_new(bh);
464 unmap_underlying_metadata(bh->b_bdev, bh->b_blocknr);
465 }
466 set_buffer_async_write(bh);
467 nr_to_submit++;
468 } while ((bh = bh->b_this_page) != head);
469
470 bh = head = page_buffers(page);
471
472 if (ext4_encrypted_inode(inode) && S_ISREG(inode->i_mode) &&
473 nr_to_submit) {
474 gfp_t gfp_flags = GFP_NOFS;
475
476 retry_encrypt:
477 data_page = ext4_encrypt(inode, page, gfp_flags);
478 if (IS_ERR(data_page)) {
479 ret = PTR_ERR(data_page);
480 if (ret == -ENOMEM && wbc->sync_mode == WB_SYNC_ALL) {
481 if (io->io_bio) {
482 ext4_io_submit(io);
483 congestion_wait(BLK_RW_ASYNC, HZ/50);
484 }
485 gfp_flags |= __GFP_NOFAIL;
486 goto retry_encrypt;
487 }
488 data_page = NULL;
489 goto out;
490 }
491 }
492
493 /* Now submit buffers to write */
494 do {
495 if (!buffer_async_write(bh))
496 continue;
497 ret = io_submit_add_bh(io, inode,
498 data_page ? data_page : page, bh);
499 if (ret) {
500 /*
501 * We only get here on ENOMEM. Not much else
502 * we can do but mark the page as dirty, and
503 * better luck next time.
504 */
505 break;
506 }
507 nr_submitted++;
508 clear_buffer_dirty(bh);
509 } while ((bh = bh->b_this_page) != head);
510
511 /* Error stopped previous loop? Clean up buffers... */
512 if (ret) {
513 out:
514 if (data_page)
515 ext4_restore_control_page(data_page);
516 printk_ratelimited(KERN_ERR "%s: ret = %d\n", __func__, ret);
517 redirty_page_for_writepage(wbc, page);
518 do {
519 clear_buffer_async_write(bh);
520 bh = bh->b_this_page;
521 } while (bh != head);
522 }
523 unlock_page(page);
524 /* Nothing submitted - we have to end page writeback */
525 if (!nr_submitted)
526 end_page_writeback(page);
527 return ret;
528}