xref: /openbmc/linux/fs/ext4/page-io.c (revision 80ecbd24) 
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/aio.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 #include <linux/mm.h>
28 #include <linux/ratelimit.h>
29 
30 #include "ext4_jbd2.h"
31 #include "xattr.h"
32 #include "acl.h"
33 
34 static struct kmem_cache *io_end_cachep;
35 
36 int __init ext4_init_pageio(void)
37 {
38 	io_end_cachep = KMEM_CACHE(ext4_io_end, SLAB_RECLAIM_ACCOUNT);
39 	if (io_end_cachep == NULL)
40 		return -ENOMEM;
41 	return 0;
42 }
43 
44 void ext4_exit_pageio(void)
45 {
46 	kmem_cache_destroy(io_end_cachep);
47 }
48 
49 /*
50  * Print an buffer I/O error compatible with the fs/buffer.c.  This
51  * provides compatibility with dmesg scrapers that look for a specific
52  * buffer I/O error message.  We really need a unified error reporting
53  * structure to userspace ala Digital Unix's uerf system, but it's
54  * probably not going to happen in my lifetime, due to LKML politics...
55  */
56 static void buffer_io_error(struct buffer_head *bh)
57 {
58 	char b[BDEVNAME_SIZE];
59 	printk_ratelimited(KERN_ERR "Buffer I/O error on device %s, logical block %llu\n",
60 			bdevname(bh->b_bdev, b),
61 			(unsigned long long)bh->b_blocknr);
62 }
63 
64 static void ext4_finish_bio(struct bio *bio)
65 {
66 	int i;
67 	int error = !test_bit(BIO_UPTODATE, &bio->bi_flags);
68 
69 	for (i = 0; i < bio->bi_vcnt; i++) {
70 		struct bio_vec *bvec = &bio->bi_io_vec[i];
71 		struct page *page = bvec->bv_page;
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 		if (error) {
82 			SetPageError(page);
83 			set_bit(AS_EIO, &page->mapping->flags);
84 		}
85 		bh = head = page_buffers(page);
86 		/*
87 		 * We check all buffers in the page under BH_Uptodate_Lock
88 		 * to avoid races with other end io clearing async_write flags
89 		 */
90 		local_irq_save(flags);
91 		bit_spin_lock(BH_Uptodate_Lock, &head->b_state);
92 		do {
93 			if (bh_offset(bh) < bio_start ||
94 			    bh_offset(bh) + bh->b_size > bio_end) {
95 				if (buffer_async_write(bh))
96 					under_io++;
97 				continue;
98 			}
99 			clear_buffer_async_write(bh);
100 			if (error)
101 				buffer_io_error(bh);
102 		} while ((bh = bh->b_this_page) != head);
103 		bit_spin_unlock(BH_Uptodate_Lock, &head->b_state);
104 		local_irq_restore(flags);
105 		if (!under_io)
106 			end_page_writeback(page);
107 	}
108 }
109 
110 static void ext4_release_io_end(ext4_io_end_t *io_end)
111 {
112 	struct bio *bio, *next_bio;
113 
114 	BUG_ON(!list_empty(&io_end->list));
115 	BUG_ON(io_end->flag & EXT4_IO_END_UNWRITTEN);
116 	WARN_ON(io_end->handle);
117 
118 	if (atomic_dec_and_test(&EXT4_I(io_end->inode)->i_ioend_count))
119 		wake_up_all(ext4_ioend_wq(io_end->inode));
120 
121 	for (bio = io_end->bio; bio; bio = next_bio) {
122 		next_bio = bio->bi_private;
123 		ext4_finish_bio(bio);
124 		bio_put(bio);
125 	}
126 	if (io_end->flag & EXT4_IO_END_DIRECT)
127 		inode_dio_done(io_end->inode);
128 	if (io_end->iocb)
129 		aio_complete(io_end->iocb, io_end->result, 0);
130 	kmem_cache_free(io_end_cachep, io_end);
131 }
132 
133 static void ext4_clear_io_unwritten_flag(ext4_io_end_t *io_end)
134 {
135 	struct inode *inode = io_end->inode;
136 
137 	io_end->flag &= ~EXT4_IO_END_UNWRITTEN;
138 	/* Wake up anyone waiting on unwritten extent conversion */
139 	if (atomic_dec_and_test(&EXT4_I(inode)->i_unwritten))
140 		wake_up_all(ext4_ioend_wq(inode));
141 }
142 
143 /*
144  * Check a range of space and convert unwritten extents to written. Note that
145  * we are protected from truncate touching same part of extent tree by the
146  * fact that truncate code waits for all DIO to finish (thus exclusion from
147  * direct IO is achieved) and also waits for PageWriteback bits. Thus we
148  * cannot get to ext4_ext_truncate() before all IOs overlapping that range are
149  * completed (happens from ext4_free_ioend()).
150  */
151 static int ext4_end_io(ext4_io_end_t *io)
152 {
153 	struct inode *inode = io->inode;
154 	loff_t offset = io->offset;
155 	ssize_t size = io->size;
156 	handle_t *handle = io->handle;
157 	int ret = 0;
158 
159 	ext4_debug("ext4_end_io_nolock: io 0x%p from inode %lu,list->next 0x%p,"
160 		   "list->prev 0x%p\n",
161 		   io, inode->i_ino, io->list.next, io->list.prev);
162 
163 	io->handle = NULL;	/* Following call will use up the handle */
164 	ret = ext4_convert_unwritten_extents(handle, inode, offset, size);
165 	if (ret < 0) {
166 		ext4_msg(inode->i_sb, KERN_EMERG,
167 			 "failed to convert unwritten extents to written "
168 			 "extents -- potential data loss!  "
169 			 "(inode %lu, offset %llu, size %zd, error %d)",
170 			 inode->i_ino, offset, size, ret);
171 	}
172 	ext4_clear_io_unwritten_flag(io);
173 	ext4_release_io_end(io);
174 	return ret;
175 }
176 
177 static void dump_completed_IO(struct inode *inode, struct list_head *head)
178 {
179 #ifdef	EXT4FS_DEBUG
180 	struct list_head *cur, *before, *after;
181 	ext4_io_end_t *io, *io0, *io1;
182 
183 	if (list_empty(head))
184 		return;
185 
186 	ext4_debug("Dump inode %lu completed io list\n", inode->i_ino);
187 	list_for_each_entry(io, head, list) {
188 		cur = &io->list;
189 		before = cur->prev;
190 		io0 = container_of(before, ext4_io_end_t, list);
191 		after = cur->next;
192 		io1 = container_of(after, ext4_io_end_t, list);
193 
194 		ext4_debug("io 0x%p from inode %lu,prev 0x%p,next 0x%p\n",
195 			    io, inode->i_ino, io0, io1);
196 	}
197 #endif
198 }
199 
200 /* Add the io_end to per-inode completed end_io list. */
201 static void ext4_add_complete_io(ext4_io_end_t *io_end)
202 {
203 	struct ext4_inode_info *ei = EXT4_I(io_end->inode);
204 	struct workqueue_struct *wq;
205 	unsigned long flags;
206 
207 	BUG_ON(!(io_end->flag & EXT4_IO_END_UNWRITTEN));
208 	spin_lock_irqsave(&ei->i_completed_io_lock, flags);
209 	if (io_end->handle) {
210 		wq = EXT4_SB(io_end->inode->i_sb)->rsv_conversion_wq;
211 		if (list_empty(&ei->i_rsv_conversion_list))
212 			queue_work(wq, &ei->i_rsv_conversion_work);
213 		list_add_tail(&io_end->list, &ei->i_rsv_conversion_list);
214 	} else {
215 		wq = EXT4_SB(io_end->inode->i_sb)->unrsv_conversion_wq;
216 		if (list_empty(&ei->i_unrsv_conversion_list))
217 			queue_work(wq, &ei->i_unrsv_conversion_work);
218 		list_add_tail(&io_end->list, &ei->i_unrsv_conversion_list);
219 	}
220 	spin_unlock_irqrestore(&ei->i_completed_io_lock, flags);
221 }
222 
223 static int ext4_do_flush_completed_IO(struct inode *inode,
224 				      struct list_head *head)
225 {
226 	ext4_io_end_t *io;
227 	struct list_head unwritten;
228 	unsigned long flags;
229 	struct ext4_inode_info *ei = EXT4_I(inode);
230 	int err, ret = 0;
231 
232 	spin_lock_irqsave(&ei->i_completed_io_lock, flags);
233 	dump_completed_IO(inode, head);
234 	list_replace_init(head, &unwritten);
235 	spin_unlock_irqrestore(&ei->i_completed_io_lock, flags);
236 
237 	while (!list_empty(&unwritten)) {
238 		io = list_entry(unwritten.next, ext4_io_end_t, list);
239 		BUG_ON(!(io->flag & EXT4_IO_END_UNWRITTEN));
240 		list_del_init(&io->list);
241 
242 		err = ext4_end_io(io);
243 		if (unlikely(!ret && err))
244 			ret = err;
245 	}
246 	return ret;
247 }
248 
249 /*
250  * work on completed IO, to convert unwritten extents to extents
251  */
252 void ext4_end_io_rsv_work(struct work_struct *work)
253 {
254 	struct ext4_inode_info *ei = container_of(work, struct ext4_inode_info,
255 						  i_rsv_conversion_work);
256 	ext4_do_flush_completed_IO(&ei->vfs_inode, &ei->i_rsv_conversion_list);
257 }
258 
259 void ext4_end_io_unrsv_work(struct work_struct *work)
260 {
261 	struct ext4_inode_info *ei = container_of(work, struct ext4_inode_info,
262 						  i_unrsv_conversion_work);
263 	ext4_do_flush_completed_IO(&ei->vfs_inode, &ei->i_unrsv_conversion_list);
264 }
265 
266 ext4_io_end_t *ext4_init_io_end(struct inode *inode, gfp_t flags)
267 {
268 	ext4_io_end_t *io = kmem_cache_zalloc(io_end_cachep, flags);
269 	if (io) {
270 		atomic_inc(&EXT4_I(inode)->i_ioend_count);
271 		io->inode = inode;
272 		INIT_LIST_HEAD(&io->list);
273 		atomic_set(&io->count, 1);
274 	}
275 	return io;
276 }
277 
278 void ext4_put_io_end_defer(ext4_io_end_t *io_end)
279 {
280 	if (atomic_dec_and_test(&io_end->count)) {
281 		if (!(io_end->flag & EXT4_IO_END_UNWRITTEN) || !io_end->size) {
282 			ext4_release_io_end(io_end);
283 			return;
284 		}
285 		ext4_add_complete_io(io_end);
286 	}
287 }
288 
289 int ext4_put_io_end(ext4_io_end_t *io_end)
290 {
291 	int err = 0;
292 
293 	if (atomic_dec_and_test(&io_end->count)) {
294 		if (io_end->flag & EXT4_IO_END_UNWRITTEN) {
295 			err = ext4_convert_unwritten_extents(io_end->handle,
296 						io_end->inode, io_end->offset,
297 						io_end->size);
298 			io_end->handle = NULL;
299 			ext4_clear_io_unwritten_flag(io_end);
300 		}
301 		ext4_release_io_end(io_end);
302 	}
303 	return err;
304 }
305 
306 ext4_io_end_t *ext4_get_io_end(ext4_io_end_t *io_end)
307 {
308 	atomic_inc(&io_end->count);
309 	return io_end;
310 }
311 
312 /* BIO completion function for page writeback */
313 static void ext4_end_bio(struct bio *bio, int error)
314 {
315 	ext4_io_end_t *io_end = bio->bi_private;
316 	sector_t bi_sector = bio->bi_sector;
317 
318 	BUG_ON(!io_end);
319 	bio->bi_end_io = NULL;
320 	if (test_bit(BIO_UPTODATE, &bio->bi_flags))
321 		error = 0;
322 
323 	if (error) {
324 		struct inode *inode = io_end->inode;
325 
326 		ext4_warning(inode->i_sb, "I/O error writing to inode %lu "
327 			     "(offset %llu size %ld starting block %llu)",
328 			     inode->i_ino,
329 			     (unsigned long long) io_end->offset,
330 			     (long) io_end->size,
331 			     (unsigned long long)
332 			     bi_sector >> (inode->i_blkbits - 9));
333 	}
334 
335 	if (io_end->flag & EXT4_IO_END_UNWRITTEN) {
336 		/*
337 		 * Link bio into list hanging from io_end. We have to do it
338 		 * atomically as bio completions can be racing against each
339 		 * other.
340 		 */
341 		bio->bi_private = xchg(&io_end->bio, bio);
342 		ext4_put_io_end_defer(io_end);
343 	} else {
344 		/*
345 		 * Drop io_end reference early. Inode can get freed once
346 		 * we finish the bio.
347 		 */
348 		ext4_put_io_end_defer(io_end);
349 		ext4_finish_bio(bio);
350 		bio_put(bio);
351 	}
352 }
353 
354 void ext4_io_submit(struct ext4_io_submit *io)
355 {
356 	struct bio *bio = io->io_bio;
357 
358 	if (bio) {
359 		bio_get(io->io_bio);
360 		submit_bio(io->io_op, io->io_bio);
361 		BUG_ON(bio_flagged(io->io_bio, BIO_EOPNOTSUPP));
362 		bio_put(io->io_bio);
363 	}
364 	io->io_bio = NULL;
365 }
366 
367 void ext4_io_submit_init(struct ext4_io_submit *io,
368 			 struct writeback_control *wbc)
369 {
370 	io->io_op = (wbc->sync_mode == WB_SYNC_ALL ?  WRITE_SYNC : WRITE);
371 	io->io_bio = NULL;
372 	io->io_end = NULL;
373 }
374 
375 static int io_submit_init_bio(struct ext4_io_submit *io,
376 			      struct buffer_head *bh)
377 {
378 	int nvecs = bio_get_nr_vecs(bh->b_bdev);
379 	struct bio *bio;
380 
381 	bio = bio_alloc(GFP_NOIO, min(nvecs, BIO_MAX_PAGES));
382 	if (!bio)
383 		return -ENOMEM;
384 	bio->bi_sector = bh->b_blocknr * (bh->b_size >> 9);
385 	bio->bi_bdev = bh->b_bdev;
386 	bio->bi_end_io = ext4_end_bio;
387 	bio->bi_private = ext4_get_io_end(io->io_end);
388 	io->io_bio = bio;
389 	io->io_next_block = bh->b_blocknr;
390 	return 0;
391 }
392 
393 static int io_submit_add_bh(struct ext4_io_submit *io,
394 			    struct inode *inode,
395 			    struct buffer_head *bh)
396 {
397 	int ret;
398 
399 	if (io->io_bio && bh->b_blocknr != io->io_next_block) {
400 submit_and_retry:
401 		ext4_io_submit(io);
402 	}
403 	if (io->io_bio == NULL) {
404 		ret = io_submit_init_bio(io, bh);
405 		if (ret)
406 			return ret;
407 	}
408 	ret = bio_add_page(io->io_bio, bh->b_page, bh->b_size, bh_offset(bh));
409 	if (ret != bh->b_size)
410 		goto submit_and_retry;
411 	io->io_next_block++;
412 	return 0;
413 }
414 
415 int ext4_bio_write_page(struct ext4_io_submit *io,
416 			struct page *page,
417 			int len,
418 			struct writeback_control *wbc)
419 {
420 	struct inode *inode = page->mapping->host;
421 	unsigned block_start, blocksize;
422 	struct buffer_head *bh, *head;
423 	int ret = 0;
424 	int nr_submitted = 0;
425 
426 	blocksize = 1 << inode->i_blkbits;
427 
428 	BUG_ON(!PageLocked(page));
429 	BUG_ON(PageWriteback(page));
430 
431 	set_page_writeback(page);
432 	ClearPageError(page);
433 
434 	/*
435 	 * In the first loop we prepare and mark buffers to submit. We have to
436 	 * mark all buffers in the page before submitting so that
437 	 * end_page_writeback() cannot be called from ext4_bio_end_io() when IO
438 	 * on the first buffer finishes and we are still working on submitting
439 	 * the second buffer.
440 	 */
441 	bh = head = page_buffers(page);
442 	do {
443 		block_start = bh_offset(bh);
444 		if (block_start >= len) {
445 			/*
446 			 * Comments copied from block_write_full_page_endio:
447 			 *
448 			 * The page straddles i_size.  It must be zeroed out on
449 			 * each and every writepage invocation because it may
450 			 * be mmapped.  "A file is mapped in multiples of the
451 			 * page size.  For a file that is not a multiple of
452 			 * the  page size, the remaining memory is zeroed when
453 			 * mapped, and writes to that region are not written
454 			 * out to the file."
455 			 */
456 			zero_user_segment(page, block_start,
457 					  block_start + blocksize);
458 			clear_buffer_dirty(bh);
459 			set_buffer_uptodate(bh);
460 			continue;
461 		}
462 		if (!buffer_dirty(bh) || buffer_delay(bh) ||
463 		    !buffer_mapped(bh) || buffer_unwritten(bh)) {
464 			/* A hole? We can safely clear the dirty bit */
465 			if (!buffer_mapped(bh))
466 				clear_buffer_dirty(bh);
467 			if (io->io_bio)
468 				ext4_io_submit(io);
469 			continue;
470 		}
471 		if (buffer_new(bh)) {
472 			clear_buffer_new(bh);
473 			unmap_underlying_metadata(bh->b_bdev, bh->b_blocknr);
474 		}
475 		set_buffer_async_write(bh);
476 	} while ((bh = bh->b_this_page) != head);
477 
478 	/* Now submit buffers to write */
479 	bh = head = page_buffers(page);
480 	do {
481 		if (!buffer_async_write(bh))
482 			continue;
483 		ret = io_submit_add_bh(io, inode, bh);
484 		if (ret) {
485 			/*
486 			 * We only get here on ENOMEM.  Not much else
487 			 * we can do but mark the page as dirty, and
488 			 * better luck next time.
489 			 */
490 			redirty_page_for_writepage(wbc, page);
491 			break;
492 		}
493 		nr_submitted++;
494 		clear_buffer_dirty(bh);
495 	} while ((bh = bh->b_this_page) != head);
496 
497 	/* Error stopped previous loop? Clean up buffers... */
498 	if (ret) {
499 		do {
500 			clear_buffer_async_write(bh);
501 			bh = bh->b_this_page;
502 		} while (bh != head);
503 	}
504 	unlock_page(page);
505 	/* Nothing submitted - we have to end page writeback */
506 	if (!nr_submitted)
507 		end_page_writeback(page);
508 	return ret;
509 }
510