xref: /openbmc/linux/fs/ext4/page-io.c (revision cf028200) 
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 
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 
47 void ext4_exit_pageio(void)
48 {
49 	kmem_cache_destroy(io_end_cachep);
50 	kmem_cache_destroy(io_page_cachep);
51 }
52 
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 
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 
69 void ext4_free_io_end(ext4_io_end_t *io)
70 {
71 	int i;
72 
73 	BUG_ON(!io);
74 	BUG_ON(!list_empty(&io->list));
75 	BUG_ON(io->flag & EXT4_IO_END_UNWRITTEN);
76 
77 	if (io->page)
78 		put_page(io->page);
79 	for (i = 0; i < io->num_io_pages; i++)
80 		put_io_page(io->pages[i]);
81 	io->num_io_pages = 0;
82 	if (atomic_dec_and_test(&EXT4_I(io->inode)->i_ioend_count))
83 		wake_up_all(ext4_ioend_wq(io->inode));
84 	kmem_cache_free(io_end_cachep, io);
85 }
86 
87 /* check a range of space and convert unwritten extents to written. */
88 static int ext4_end_io(ext4_io_end_t *io)
89 {
90 	struct inode *inode = io->inode;
91 	loff_t offset = io->offset;
92 	ssize_t size = io->size;
93 	int ret = 0;
94 
95 	ext4_debug("ext4_end_io_nolock: io 0x%p from inode %lu,list->next 0x%p,"
96 		   "list->prev 0x%p\n",
97 		   io, inode->i_ino, io->list.next, io->list.prev);
98 
99 	ret = ext4_convert_unwritten_extents(inode, offset, size);
100 	if (ret < 0) {
101 		ext4_msg(inode->i_sb, KERN_EMERG,
102 			 "failed to convert unwritten extents to written "
103 			 "extents -- potential data loss!  "
104 			 "(inode %lu, offset %llu, size %zd, error %d)",
105 			 inode->i_ino, offset, size, ret);
106 	}
107 	if (io->iocb)
108 		aio_complete(io->iocb, io->result, 0);
109 
110 	if (io->flag & EXT4_IO_END_DIRECT)
111 		inode_dio_done(inode);
112 	/* Wake up anyone waiting on unwritten extent conversion */
113 	if (atomic_dec_and_test(&EXT4_I(inode)->i_unwritten))
114 		wake_up_all(ext4_ioend_wq(io->inode));
115 	return ret;
116 }
117 
118 static void dump_completed_IO(struct inode *inode)
119 {
120 #ifdef	EXT4FS_DEBUG
121 	struct list_head *cur, *before, *after;
122 	ext4_io_end_t *io, *io0, *io1;
123 	unsigned long flags;
124 
125 	if (list_empty(&EXT4_I(inode)->i_completed_io_list)) {
126 		ext4_debug("inode %lu completed_io list is empty\n",
127 			   inode->i_ino);
128 		return;
129 	}
130 
131 	ext4_debug("Dump inode %lu completed_io list\n", inode->i_ino);
132 	list_for_each_entry(io, &EXT4_I(inode)->i_completed_io_list, list) {
133 		cur = &io->list;
134 		before = cur->prev;
135 		io0 = container_of(before, ext4_io_end_t, list);
136 		after = cur->next;
137 		io1 = container_of(after, ext4_io_end_t, list);
138 
139 		ext4_debug("io 0x%p from inode %lu,prev 0x%p,next 0x%p\n",
140 			    io, inode->i_ino, io0, io1);
141 	}
142 #endif
143 }
144 
145 /* Add the io_end to per-inode completed end_io list. */
146 void ext4_add_complete_io(ext4_io_end_t *io_end)
147 {
148 	struct ext4_inode_info *ei = EXT4_I(io_end->inode);
149 	struct workqueue_struct *wq;
150 	unsigned long flags;
151 
152 	BUG_ON(!(io_end->flag & EXT4_IO_END_UNWRITTEN));
153 	wq = EXT4_SB(io_end->inode->i_sb)->dio_unwritten_wq;
154 
155 	spin_lock_irqsave(&ei->i_completed_io_lock, flags);
156 	if (list_empty(&ei->i_completed_io_list)) {
157 		io_end->flag |= EXT4_IO_END_QUEUED;
158 		queue_work(wq, &io_end->work);
159 	}
160 	list_add_tail(&io_end->list, &ei->i_completed_io_list);
161 	spin_unlock_irqrestore(&ei->i_completed_io_lock, flags);
162 }
163 
164 static int ext4_do_flush_completed_IO(struct inode *inode,
165 				      ext4_io_end_t *work_io)
166 {
167 	ext4_io_end_t *io;
168 	struct list_head unwritten, complete, to_free;
169 	unsigned long flags;
170 	struct ext4_inode_info *ei = EXT4_I(inode);
171 	int err, ret = 0;
172 
173 	INIT_LIST_HEAD(&complete);
174 	INIT_LIST_HEAD(&to_free);
175 
176 	spin_lock_irqsave(&ei->i_completed_io_lock, flags);
177 	dump_completed_IO(inode);
178 	list_replace_init(&ei->i_completed_io_list, &unwritten);
179 	spin_unlock_irqrestore(&ei->i_completed_io_lock, flags);
180 
181 	while (!list_empty(&unwritten)) {
182 		io = list_entry(unwritten.next, ext4_io_end_t, list);
183 		BUG_ON(!(io->flag & EXT4_IO_END_UNWRITTEN));
184 		list_del_init(&io->list);
185 
186 		err = ext4_end_io(io);
187 		if (unlikely(!ret && err))
188 			ret = err;
189 
190 		list_add_tail(&io->list, &complete);
191 	}
192 	spin_lock_irqsave(&ei->i_completed_io_lock, flags);
193 	while (!list_empty(&complete)) {
194 		io = list_entry(complete.next, ext4_io_end_t, list);
195 		io->flag &= ~EXT4_IO_END_UNWRITTEN;
196 		/* end_io context can not be destroyed now because it still
197 		 * used by queued worker. Worker thread will destroy it later */
198 		if (io->flag & EXT4_IO_END_QUEUED)
199 			list_del_init(&io->list);
200 		else
201 			list_move(&io->list, &to_free);
202 	}
203 	/* If we are called from worker context, it is time to clear queued
204 	 * flag, and destroy it's end_io if it was converted already */
205 	if (work_io) {
206 		work_io->flag &= ~EXT4_IO_END_QUEUED;
207 		if (!(work_io->flag & EXT4_IO_END_UNWRITTEN))
208 			list_add_tail(&work_io->list, &to_free);
209 	}
210 	spin_unlock_irqrestore(&ei->i_completed_io_lock, flags);
211 
212 	while (!list_empty(&to_free)) {
213 		io = list_entry(to_free.next, ext4_io_end_t, list);
214 		list_del_init(&io->list);
215 		ext4_free_io_end(io);
216 	}
217 	return ret;
218 }
219 
220 /*
221  * work on completed aio dio IO, to convert unwritten extents to extents
222  */
223 static void ext4_end_io_work(struct work_struct *work)
224 {
225 	ext4_io_end_t *io = container_of(work, ext4_io_end_t, work);
226 	ext4_do_flush_completed_IO(io->inode, io);
227 }
228 
229 int ext4_flush_unwritten_io(struct inode *inode)
230 {
231 	int ret;
232 	WARN_ON_ONCE(!mutex_is_locked(&inode->i_mutex) &&
233 		     !(inode->i_state & I_FREEING));
234 	ret = ext4_do_flush_completed_IO(inode, NULL);
235 	ext4_unwritten_wait(inode);
236 	return ret;
237 }
238 
239 ext4_io_end_t *ext4_init_io_end(struct inode *inode, gfp_t flags)
240 {
241 	ext4_io_end_t *io = kmem_cache_zalloc(io_end_cachep, flags);
242 	if (io) {
243 		atomic_inc(&EXT4_I(inode)->i_ioend_count);
244 		io->inode = inode;
245 		INIT_WORK(&io->work, ext4_end_io_work);
246 		INIT_LIST_HEAD(&io->list);
247 	}
248 	return io;
249 }
250 
251 /*
252  * Print an buffer I/O error compatible with the fs/buffer.c.  This
253  * provides compatibility with dmesg scrapers that look for a specific
254  * buffer I/O error message.  We really need a unified error reporting
255  * structure to userspace ala Digital Unix's uerf system, but it's
256  * probably not going to happen in my lifetime, due to LKML politics...
257  */
258 static void buffer_io_error(struct buffer_head *bh)
259 {
260 	char b[BDEVNAME_SIZE];
261 	printk(KERN_ERR "Buffer I/O error on device %s, logical block %llu\n",
262 			bdevname(bh->b_bdev, b),
263 			(unsigned long long)bh->b_blocknr);
264 }
265 
266 static void ext4_end_bio(struct bio *bio, int error)
267 {
268 	ext4_io_end_t *io_end = bio->bi_private;
269 	struct inode *inode;
270 	int i;
271 	sector_t bi_sector = bio->bi_sector;
272 
273 	BUG_ON(!io_end);
274 	bio->bi_private = NULL;
275 	bio->bi_end_io = NULL;
276 	if (test_bit(BIO_UPTODATE, &bio->bi_flags))
277 		error = 0;
278 	bio_put(bio);
279 
280 	for (i = 0; i < io_end->num_io_pages; i++) {
281 		struct page *page = io_end->pages[i]->p_page;
282 		struct buffer_head *bh, *head;
283 		loff_t offset;
284 		loff_t io_end_offset;
285 
286 		if (error) {
287 			SetPageError(page);
288 			set_bit(AS_EIO, &page->mapping->flags);
289 			head = page_buffers(page);
290 			BUG_ON(!head);
291 
292 			io_end_offset = io_end->offset + io_end->size;
293 
294 			offset = (sector_t) page->index << PAGE_CACHE_SHIFT;
295 			bh = head;
296 			do {
297 				if ((offset >= io_end->offset) &&
298 				    (offset+bh->b_size <= io_end_offset))
299 					buffer_io_error(bh);
300 
301 				offset += bh->b_size;
302 				bh = bh->b_this_page;
303 			} while (bh != head);
304 		}
305 
306 		put_io_page(io_end->pages[i]);
307 	}
308 	io_end->num_io_pages = 0;
309 	inode = io_end->inode;
310 
311 	if (error) {
312 		io_end->flag |= EXT4_IO_END_ERROR;
313 		ext4_warning(inode->i_sb, "I/O error writing to inode %lu "
314 			     "(offset %llu size %ld starting block %llu)",
315 			     inode->i_ino,
316 			     (unsigned long long) io_end->offset,
317 			     (long) io_end->size,
318 			     (unsigned long long)
319 			     bi_sector >> (inode->i_blkbits - 9));
320 	}
321 
322 	if (!(io_end->flag & EXT4_IO_END_UNWRITTEN)) {
323 		ext4_free_io_end(io_end);
324 		return;
325 	}
326 
327 	ext4_add_complete_io(io_end);
328 }
329 
330 void ext4_io_submit(struct ext4_io_submit *io)
331 {
332 	struct bio *bio = io->io_bio;
333 
334 	if (bio) {
335 		bio_get(io->io_bio);
336 		submit_bio(io->io_op, io->io_bio);
337 		BUG_ON(bio_flagged(io->io_bio, BIO_EOPNOTSUPP));
338 		bio_put(io->io_bio);
339 	}
340 	io->io_bio = NULL;
341 	io->io_op = 0;
342 	io->io_end = NULL;
343 }
344 
345 static int io_submit_init(struct ext4_io_submit *io,
346 			  struct inode *inode,
347 			  struct writeback_control *wbc,
348 			  struct buffer_head *bh)
349 {
350 	ext4_io_end_t *io_end;
351 	struct page *page = bh->b_page;
352 	int nvecs = bio_get_nr_vecs(bh->b_bdev);
353 	struct bio *bio;
354 
355 	io_end = ext4_init_io_end(inode, GFP_NOFS);
356 	if (!io_end)
357 		return -ENOMEM;
358 	bio = bio_alloc(GFP_NOIO, min(nvecs, BIO_MAX_PAGES));
359 	bio->bi_sector = bh->b_blocknr * (bh->b_size >> 9);
360 	bio->bi_bdev = bh->b_bdev;
361 	bio->bi_private = io->io_end = io_end;
362 	bio->bi_end_io = ext4_end_bio;
363 
364 	io_end->offset = (page->index << PAGE_CACHE_SHIFT) + bh_offset(bh);
365 
366 	io->io_bio = bio;
367 	io->io_op = (wbc->sync_mode == WB_SYNC_ALL ?  WRITE_SYNC : WRITE);
368 	io->io_next_block = bh->b_blocknr;
369 	return 0;
370 }
371 
372 static int io_submit_add_bh(struct ext4_io_submit *io,
373 			    struct ext4_io_page *io_page,
374 			    struct inode *inode,
375 			    struct writeback_control *wbc,
376 			    struct buffer_head *bh)
377 {
378 	ext4_io_end_t *io_end;
379 	int ret;
380 
381 	if (buffer_new(bh)) {
382 		clear_buffer_new(bh);
383 		unmap_underlying_metadata(bh->b_bdev, bh->b_blocknr);
384 	}
385 
386 	if (!buffer_mapped(bh) || buffer_delay(bh)) {
387 		if (!buffer_mapped(bh))
388 			clear_buffer_dirty(bh);
389 		if (io->io_bio)
390 			ext4_io_submit(io);
391 		return 0;
392 	}
393 
394 	if (io->io_bio && bh->b_blocknr != io->io_next_block) {
395 submit_and_retry:
396 		ext4_io_submit(io);
397 	}
398 	if (io->io_bio == NULL) {
399 		ret = io_submit_init(io, inode, wbc, bh);
400 		if (ret)
401 			return ret;
402 	}
403 	io_end = io->io_end;
404 	if ((io_end->num_io_pages >= MAX_IO_PAGES) &&
405 	    (io_end->pages[io_end->num_io_pages-1] != io_page))
406 		goto submit_and_retry;
407 	if (buffer_uninit(bh))
408 		ext4_set_io_unwritten_flag(inode, io_end);
409 	io->io_end->size += bh->b_size;
410 	io->io_next_block++;
411 	ret = bio_add_page(io->io_bio, bh->b_page, bh->b_size, bh_offset(bh));
412 	if (ret != bh->b_size)
413 		goto submit_and_retry;
414 	if ((io_end->num_io_pages == 0) ||
415 	    (io_end->pages[io_end->num_io_pages-1] != io_page)) {
416 		io_end->pages[io_end->num_io_pages++] = io_page;
417 		atomic_inc(&io_page->p_count);
418 	}
419 	return 0;
420 }
421 
422 int ext4_bio_write_page(struct ext4_io_submit *io,
423 			struct page *page,
424 			int len,
425 			struct writeback_control *wbc)
426 {
427 	struct inode *inode = page->mapping->host;
428 	unsigned block_start, block_end, blocksize;
429 	struct ext4_io_page *io_page;
430 	struct buffer_head *bh, *head;
431 	int ret = 0;
432 
433 	blocksize = 1 << inode->i_blkbits;
434 
435 	BUG_ON(!PageLocked(page));
436 	BUG_ON(PageWriteback(page));
437 
438 	io_page = kmem_cache_alloc(io_page_cachep, GFP_NOFS);
439 	if (!io_page) {
440 		set_page_dirty(page);
441 		unlock_page(page);
442 		return -ENOMEM;
443 	}
444 	io_page->p_page = page;
445 	atomic_set(&io_page->p_count, 1);
446 	get_page(page);
447 	set_page_writeback(page);
448 	ClearPageError(page);
449 
450 	for (bh = head = page_buffers(page), block_start = 0;
451 	     bh != head || !block_start;
452 	     block_start = block_end, bh = bh->b_this_page) {
453 
454 		block_end = block_start + blocksize;
455 		if (block_start >= len) {
456 			/*
457 			 * Comments copied from block_write_full_page_endio:
458 			 *
459 			 * The page straddles i_size.  It must be zeroed out on
460 			 * each and every writepage invocation because it may
461 			 * be mmapped.  "A file is mapped in multiples of the
462 			 * page size.  For a file that is not a multiple of
463 			 * the  page size, the remaining memory is zeroed when
464 			 * mapped, and writes to that region are not written
465 			 * out to the file."
466 			 */
467 			zero_user_segment(page, block_start, block_end);
468 			clear_buffer_dirty(bh);
469 			set_buffer_uptodate(bh);
470 			continue;
471 		}
472 		clear_buffer_dirty(bh);
473 		ret = io_submit_add_bh(io, io_page, inode, wbc, bh);
474 		if (ret) {
475 			/*
476 			 * We only get here on ENOMEM.  Not much else
477 			 * we can do but mark the page as dirty, and
478 			 * better luck next time.
479 			 */
480 			set_page_dirty(page);
481 			break;
482 		}
483 	}
484 	unlock_page(page);
485 	/*
486 	 * If the page was truncated before we could do the writeback,
487 	 * or we had a memory allocation error while trying to write
488 	 * the first buffer head, we won't have submitted any pages for
489 	 * I/O.  In that case we need to make sure we've cleared the
490 	 * PageWriteback bit from the page to prevent the system from
491 	 * wedging later on.
492 	 */
493 	put_io_page(io_page);
494 	return ret;
495 }
496