1 // SPDX-License-Identifier: GPL-2.0
3 * linux/fs/ext4/page-io.c
5 * This contains the new page_io functions for ext4
7 * Written by Theodore Ts'o, 2010.
11 #include <linux/time.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>
27 #include <linux/backing-dev.h>
29 #include "ext4_jbd2.h"
33 static struct kmem_cache *io_end_cachep;
34 static struct kmem_cache *io_end_vec_cachep;
36 int __init ext4_init_pageio(void)
38 io_end_cachep = KMEM_CACHE(ext4_io_end, SLAB_RECLAIM_ACCOUNT);
39 if (io_end_cachep == NULL)
42 io_end_vec_cachep = KMEM_CACHE(ext4_io_end_vec, 0);
43 if (io_end_vec_cachep == NULL) {
44 kmem_cache_destroy(io_end_cachep);
50 void ext4_exit_pageio(void)
52 kmem_cache_destroy(io_end_cachep);
53 kmem_cache_destroy(io_end_vec_cachep);
56 struct ext4_io_end_vec *ext4_alloc_io_end_vec(ext4_io_end_t *io_end)
58 struct ext4_io_end_vec *io_end_vec;
60 io_end_vec = kmem_cache_zalloc(io_end_vec_cachep, GFP_NOFS);
62 return ERR_PTR(-ENOMEM);
63 INIT_LIST_HEAD(&io_end_vec->list);
64 list_add_tail(&io_end_vec->list, &io_end->list_vec);
68 static void ext4_free_io_end_vec(ext4_io_end_t *io_end)
70 struct ext4_io_end_vec *io_end_vec, *tmp;
72 if (list_empty(&io_end->list_vec))
74 list_for_each_entry_safe(io_end_vec, tmp, &io_end->list_vec, list) {
75 list_del(&io_end_vec->list);
76 kmem_cache_free(io_end_vec_cachep, io_end_vec);
80 struct ext4_io_end_vec *ext4_last_io_end_vec(ext4_io_end_t *io_end)
82 BUG_ON(list_empty(&io_end->list_vec));
83 return list_last_entry(&io_end->list_vec, struct ext4_io_end_vec, list);
87 * Print an buffer I/O error compatible with the fs/buffer.c. This
88 * provides compatibility with dmesg scrapers that look for a specific
89 * buffer I/O error message. We really need a unified error reporting
90 * structure to userspace ala Digital Unix's uerf system, but it's
91 * probably not going to happen in my lifetime, due to LKML politics...
93 static void buffer_io_error(struct buffer_head *bh)
95 printk_ratelimited(KERN_ERR "Buffer I/O error on device %pg, logical block %llu\n",
97 (unsigned long long)bh->b_blocknr);
100 static void ext4_finish_bio(struct bio *bio)
102 struct bio_vec *bvec;
103 struct bvec_iter_all iter_all;
105 bio_for_each_segment_all(bvec, bio, iter_all) {
106 struct page *page = bvec->bv_page;
107 struct page *bounce_page = NULL;
108 struct buffer_head *bh, *head;
109 unsigned bio_start = bvec->bv_offset;
110 unsigned bio_end = bio_start + bvec->bv_len;
111 unsigned under_io = 0;
117 if (fscrypt_is_bounce_page(page)) {
119 page = fscrypt_pagecache_page(bounce_page);
122 if (bio->bi_status) {
124 mapping_set_error(page->mapping, -EIO);
126 bh = head = page_buffers(page);
128 * We check all buffers in the page under b_uptodate_lock
129 * to avoid races with other end io clearing async_write flags
131 spin_lock_irqsave(&head->b_uptodate_lock, flags);
133 if (bh_offset(bh) < bio_start ||
134 bh_offset(bh) + bh->b_size > bio_end) {
135 if (buffer_async_write(bh))
139 clear_buffer_async_write(bh);
140 if (bio->bi_status) {
141 set_buffer_write_io_error(bh);
144 } while ((bh = bh->b_this_page) != head);
145 spin_unlock_irqrestore(&head->b_uptodate_lock, flags);
147 fscrypt_free_bounce_page(bounce_page);
148 end_page_writeback(page);
153 static void ext4_release_io_end(ext4_io_end_t *io_end)
155 struct bio *bio, *next_bio;
157 BUG_ON(!list_empty(&io_end->list));
158 BUG_ON(io_end->flag & EXT4_IO_END_UNWRITTEN);
159 WARN_ON(io_end->handle);
161 for (bio = io_end->bio; bio; bio = next_bio) {
162 next_bio = bio->bi_private;
163 ext4_finish_bio(bio);
166 ext4_free_io_end_vec(io_end);
167 kmem_cache_free(io_end_cachep, io_end);
171 * Check a range of space and convert unwritten extents to written. Note that
172 * we are protected from truncate touching same part of extent tree by the
173 * fact that truncate code waits for all DIO to finish (thus exclusion from
174 * direct IO is achieved) and also waits for PageWriteback bits. Thus we
175 * cannot get to ext4_ext_truncate() before all IOs overlapping that range are
176 * completed (happens from ext4_free_ioend()).
178 static int ext4_end_io_end(ext4_io_end_t *io_end)
180 struct inode *inode = io_end->inode;
181 handle_t *handle = io_end->handle;
184 ext4_debug("ext4_end_io_nolock: io_end 0x%p from inode %lu,list->next 0x%p,"
186 io_end, inode->i_ino, io_end->list.next, io_end->list.prev);
188 io_end->handle = NULL; /* Following call will use up the handle */
189 ret = ext4_convert_unwritten_io_end_vec(handle, io_end);
190 if (ret < 0 && !ext4_forced_shutdown(EXT4_SB(inode->i_sb))) {
191 ext4_msg(inode->i_sb, KERN_EMERG,
192 "failed to convert unwritten extents to written "
193 "extents -- potential data loss! "
194 "(inode %lu, error %d)", inode->i_ino, ret);
196 ext4_clear_io_unwritten_flag(io_end);
197 ext4_release_io_end(io_end);
201 static void dump_completed_IO(struct inode *inode, struct list_head *head)
204 struct list_head *cur, *before, *after;
205 ext4_io_end_t *io_end, *io_end0, *io_end1;
207 if (list_empty(head))
210 ext4_debug("Dump inode %lu completed io list\n", inode->i_ino);
211 list_for_each_entry(io_end, head, list) {
214 io_end0 = container_of(before, ext4_io_end_t, list);
216 io_end1 = container_of(after, ext4_io_end_t, list);
218 ext4_debug("io 0x%p from inode %lu,prev 0x%p,next 0x%p\n",
219 io_end, inode->i_ino, io_end0, io_end1);
224 /* Add the io_end to per-inode completed end_io list. */
225 static void ext4_add_complete_io(ext4_io_end_t *io_end)
227 struct ext4_inode_info *ei = EXT4_I(io_end->inode);
228 struct ext4_sb_info *sbi = EXT4_SB(io_end->inode->i_sb);
229 struct workqueue_struct *wq;
232 /* Only reserved conversions from writeback should enter here */
233 WARN_ON(!(io_end->flag & EXT4_IO_END_UNWRITTEN));
234 WARN_ON(!io_end->handle && sbi->s_journal);
235 spin_lock_irqsave(&ei->i_completed_io_lock, flags);
236 wq = sbi->rsv_conversion_wq;
237 if (list_empty(&ei->i_rsv_conversion_list))
238 queue_work(wq, &ei->i_rsv_conversion_work);
239 list_add_tail(&io_end->list, &ei->i_rsv_conversion_list);
240 spin_unlock_irqrestore(&ei->i_completed_io_lock, flags);
243 static int ext4_do_flush_completed_IO(struct inode *inode,
244 struct list_head *head)
246 ext4_io_end_t *io_end;
247 struct list_head unwritten;
249 struct ext4_inode_info *ei = EXT4_I(inode);
252 spin_lock_irqsave(&ei->i_completed_io_lock, flags);
253 dump_completed_IO(inode, head);
254 list_replace_init(head, &unwritten);
255 spin_unlock_irqrestore(&ei->i_completed_io_lock, flags);
257 while (!list_empty(&unwritten)) {
258 io_end = list_entry(unwritten.next, ext4_io_end_t, list);
259 BUG_ON(!(io_end->flag & EXT4_IO_END_UNWRITTEN));
260 list_del_init(&io_end->list);
262 err = ext4_end_io_end(io_end);
263 if (unlikely(!ret && err))
270 * work on completed IO, to convert unwritten extents to extents
272 void ext4_end_io_rsv_work(struct work_struct *work)
274 struct ext4_inode_info *ei = container_of(work, struct ext4_inode_info,
275 i_rsv_conversion_work);
276 ext4_do_flush_completed_IO(&ei->vfs_inode, &ei->i_rsv_conversion_list);
279 ext4_io_end_t *ext4_init_io_end(struct inode *inode, gfp_t flags)
281 ext4_io_end_t *io_end = kmem_cache_zalloc(io_end_cachep, flags);
284 io_end->inode = inode;
285 INIT_LIST_HEAD(&io_end->list);
286 INIT_LIST_HEAD(&io_end->list_vec);
287 atomic_set(&io_end->count, 1);
292 void ext4_put_io_end_defer(ext4_io_end_t *io_end)
294 if (atomic_dec_and_test(&io_end->count)) {
295 if (!(io_end->flag & EXT4_IO_END_UNWRITTEN) ||
296 list_empty(&io_end->list_vec)) {
297 ext4_release_io_end(io_end);
300 ext4_add_complete_io(io_end);
304 int ext4_put_io_end(ext4_io_end_t *io_end)
308 if (atomic_dec_and_test(&io_end->count)) {
309 if (io_end->flag & EXT4_IO_END_UNWRITTEN) {
310 err = ext4_convert_unwritten_io_end_vec(io_end->handle,
312 io_end->handle = NULL;
313 ext4_clear_io_unwritten_flag(io_end);
315 ext4_release_io_end(io_end);
320 ext4_io_end_t *ext4_get_io_end(ext4_io_end_t *io_end)
322 atomic_inc(&io_end->count);
326 /* BIO completion function for page writeback */
327 static void ext4_end_bio(struct bio *bio)
329 ext4_io_end_t *io_end = bio->bi_private;
330 sector_t bi_sector = bio->bi_iter.bi_sector;
331 char b[BDEVNAME_SIZE];
333 if (WARN_ONCE(!io_end, "io_end is NULL: %s: sector %Lu len %u err %d\n",
335 (long long) bio->bi_iter.bi_sector,
336 (unsigned) bio_sectors(bio),
338 ext4_finish_bio(bio);
342 bio->bi_end_io = NULL;
344 if (bio->bi_status) {
345 struct inode *inode = io_end->inode;
347 ext4_warning(inode->i_sb, "I/O error %d writing to inode %lu "
348 "starting block %llu)",
349 bio->bi_status, inode->i_ino,
351 bi_sector >> (inode->i_blkbits - 9));
352 mapping_set_error(inode->i_mapping,
353 blk_status_to_errno(bio->bi_status));
356 if (io_end->flag & EXT4_IO_END_UNWRITTEN) {
358 * Link bio into list hanging from io_end. We have to do it
359 * atomically as bio completions can be racing against each
362 bio->bi_private = xchg(&io_end->bio, bio);
363 ext4_put_io_end_defer(io_end);
366 * Drop io_end reference early. Inode can get freed once
369 ext4_put_io_end_defer(io_end);
370 ext4_finish_bio(bio);
375 void ext4_io_submit(struct ext4_io_submit *io)
377 struct bio *bio = io->io_bio;
380 int io_op_flags = io->io_wbc->sync_mode == WB_SYNC_ALL ?
382 io->io_bio->bi_write_hint = io->io_end->inode->i_write_hint;
383 bio_set_op_attrs(io->io_bio, REQ_OP_WRITE, io_op_flags);
384 submit_bio(io->io_bio);
389 void ext4_io_submit_init(struct ext4_io_submit *io,
390 struct writeback_control *wbc)
397 static void io_submit_init_bio(struct ext4_io_submit *io,
398 struct buffer_head *bh)
403 * bio_alloc will _always_ be able to allocate a bio if
404 * __GFP_DIRECT_RECLAIM is set, see comments for bio_alloc_bioset().
406 bio = bio_alloc(GFP_NOIO, BIO_MAX_PAGES);
407 fscrypt_set_bio_crypt_ctx_bh(bio, bh, GFP_NOIO);
408 bio->bi_iter.bi_sector = bh->b_blocknr * (bh->b_size >> 9);
409 bio_set_dev(bio, bh->b_bdev);
410 bio->bi_end_io = ext4_end_bio;
411 bio->bi_private = ext4_get_io_end(io->io_end);
413 io->io_next_block = bh->b_blocknr;
414 wbc_init_bio(io->io_wbc, bio);
417 static void io_submit_add_bh(struct ext4_io_submit *io,
419 struct page *pagecache_page,
420 struct page *bounce_page,
421 struct buffer_head *bh)
425 if (io->io_bio && (bh->b_blocknr != io->io_next_block ||
426 !fscrypt_mergeable_bio_bh(io->io_bio, bh))) {
430 if (io->io_bio == NULL) {
431 io_submit_init_bio(io, bh);
432 io->io_bio->bi_write_hint = inode->i_write_hint;
434 ret = bio_add_page(io->io_bio, bounce_page ?: pagecache_page,
435 bh->b_size, bh_offset(bh));
436 if (ret != bh->b_size)
437 goto submit_and_retry;
438 wbc_account_cgroup_owner(io->io_wbc, pagecache_page, bh->b_size);
442 int ext4_bio_write_page(struct ext4_io_submit *io,
445 struct writeback_control *wbc,
448 struct page *bounce_page = NULL;
449 struct inode *inode = page->mapping->host;
450 unsigned block_start;
451 struct buffer_head *bh, *head;
453 int nr_submitted = 0;
454 int nr_to_submit = 0;
456 BUG_ON(!PageLocked(page));
457 BUG_ON(PageWriteback(page));
460 set_page_writeback_keepwrite(page);
462 set_page_writeback(page);
463 ClearPageError(page);
466 * Comments copied from block_write_full_page:
468 * The page straddles i_size. It must be zeroed out on each and every
469 * writepage invocation because it may be mmapped. "A file is mapped
470 * in multiples of the page size. For a file that is not a multiple of
471 * the page size, the remaining memory is zeroed when mapped, and
472 * writes to that region are not written out to the file."
475 zero_user_segment(page, len, PAGE_SIZE);
477 * In the first loop we prepare and mark buffers to submit. We have to
478 * mark all buffers in the page before submitting so that
479 * end_page_writeback() cannot be called from ext4_bio_end_io() when IO
480 * on the first buffer finishes and we are still working on submitting
483 bh = head = page_buffers(page);
485 block_start = bh_offset(bh);
486 if (block_start >= len) {
487 clear_buffer_dirty(bh);
488 set_buffer_uptodate(bh);
491 if (!buffer_dirty(bh) || buffer_delay(bh) ||
492 !buffer_mapped(bh) || buffer_unwritten(bh)) {
493 /* A hole? We can safely clear the dirty bit */
494 if (!buffer_mapped(bh))
495 clear_buffer_dirty(bh);
501 clear_buffer_new(bh);
502 set_buffer_async_write(bh);
504 } while ((bh = bh->b_this_page) != head);
506 bh = head = page_buffers(page);
509 * If any blocks are being written to an encrypted file, encrypt them
510 * into a bounce page. For simplicity, just encrypt until the last
511 * block which might be needed. This may cause some unneeded blocks
512 * (e.g. holes) to be unnecessarily encrypted, but this is rare and
513 * can't happen in the common case of blocksize == PAGE_SIZE.
515 if (fscrypt_inode_uses_fs_layer_crypto(inode) && nr_to_submit) {
516 gfp_t gfp_flags = GFP_NOFS;
517 unsigned int enc_bytes = round_up(len, i_blocksize(inode));
520 * Since bounce page allocation uses a mempool, we can only use
521 * a waiting mask (i.e. request guaranteed allocation) on the
522 * first page of the bio. Otherwise it can deadlock.
525 gfp_flags = GFP_NOWAIT | __GFP_NOWARN;
527 bounce_page = fscrypt_encrypt_pagecache_blocks(page, enc_bytes,
529 if (IS_ERR(bounce_page)) {
530 ret = PTR_ERR(bounce_page);
531 if (ret == -ENOMEM &&
532 (io->io_bio || wbc->sync_mode == WB_SYNC_ALL)) {
533 gfp_flags = GFP_NOFS;
537 gfp_flags |= __GFP_NOFAIL;
538 congestion_wait(BLK_RW_ASYNC, HZ/50);
542 printk_ratelimited(KERN_ERR "%s: ret = %d\n", __func__, ret);
543 redirty_page_for_writepage(wbc, page);
545 clear_buffer_async_write(bh);
546 bh = bh->b_this_page;
547 } while (bh != head);
552 /* Now submit buffers to write */
554 if (!buffer_async_write(bh))
556 io_submit_add_bh(io, inode, page, bounce_page, bh);
558 clear_buffer_dirty(bh);
559 } while ((bh = bh->b_this_page) != head);
563 /* Nothing submitted - we have to end page writeback */
565 end_page_writeback(page);