xref: /openbmc/linux/fs/ext4/page-io.c (revision 63dc02bd) 
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 	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  */
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 	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  */
124 static 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;
141 requeue:
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);
164 free:
165 	ext4_free_io_end(io);
166 }
167 
168 ext4_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  */
187 static 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 
195 static 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 
268 void 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 
283 static 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 
310 static 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) {
333 submit_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 
360 int 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 }
434