2 * linux/fs/ext4/page-io.c
4 * This contains the new page_io functions for ext4
6 * Written by Theodore Ts'o, 2010.
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>
27 #include <linux/ratelimit.h>
29 #include "ext4_jbd2.h"
33 static struct kmem_cache *io_end_cachep;
35 int __init ext4_init_pageio(void)
37 io_end_cachep = KMEM_CACHE(ext4_io_end, SLAB_RECLAIM_ACCOUNT);
38 if (io_end_cachep == NULL)
43 void ext4_exit_pageio(void)
45 kmem_cache_destroy(io_end_cachep);
49 * Print an buffer I/O error compatible with the fs/buffer.c. This
50 * provides compatibility with dmesg scrapers that look for a specific
51 * buffer I/O error message. We really need a unified error reporting
52 * structure to userspace ala Digital Unix's uerf system, but it's
53 * probably not going to happen in my lifetime, due to LKML politics...
55 static void buffer_io_error(struct buffer_head *bh)
57 char b[BDEVNAME_SIZE];
58 printk_ratelimited(KERN_ERR "Buffer I/O error on device %s, logical block %llu\n",
59 bdevname(bh->b_bdev, b),
60 (unsigned long long)bh->b_blocknr);
63 static void ext4_finish_bio(struct bio *bio)
66 int error = !test_bit(BIO_UPTODATE, &bio->bi_flags);
69 bio_for_each_segment_all(bvec, bio, i) {
70 struct page *page = bvec->bv_page;
71 struct buffer_head *bh, *head;
72 unsigned bio_start = bvec->bv_offset;
73 unsigned bio_end = bio_start + bvec->bv_len;
74 unsigned under_io = 0;
82 set_bit(AS_EIO, &page->mapping->flags);
84 bh = head = page_buffers(page);
86 * We check all buffers in the page under BH_Uptodate_Lock
87 * to avoid races with other end io clearing async_write flags
89 local_irq_save(flags);
90 bit_spin_lock(BH_Uptodate_Lock, &head->b_state);
92 if (bh_offset(bh) < bio_start ||
93 bh_offset(bh) + bh->b_size > bio_end) {
94 if (buffer_async_write(bh))
98 clear_buffer_async_write(bh);
101 } while ((bh = bh->b_this_page) != head);
102 bit_spin_unlock(BH_Uptodate_Lock, &head->b_state);
103 local_irq_restore(flags);
105 end_page_writeback(page);
109 static void ext4_release_io_end(ext4_io_end_t *io_end)
111 struct bio *bio, *next_bio;
113 BUG_ON(!list_empty(&io_end->list));
114 BUG_ON(io_end->flag & EXT4_IO_END_UNWRITTEN);
115 WARN_ON(io_end->handle);
117 if (atomic_dec_and_test(&EXT4_I(io_end->inode)->i_ioend_count))
118 wake_up_all(ext4_ioend_wq(io_end->inode));
120 for (bio = io_end->bio; bio; bio = next_bio) {
121 next_bio = bio->bi_private;
122 ext4_finish_bio(bio);
125 kmem_cache_free(io_end_cachep, io_end);
128 static void ext4_clear_io_unwritten_flag(ext4_io_end_t *io_end)
130 struct inode *inode = io_end->inode;
132 io_end->flag &= ~EXT4_IO_END_UNWRITTEN;
133 /* Wake up anyone waiting on unwritten extent conversion */
134 if (atomic_dec_and_test(&EXT4_I(inode)->i_unwritten))
135 wake_up_all(ext4_ioend_wq(inode));
139 * Check a range of space and convert unwritten extents to written. Note that
140 * we are protected from truncate touching same part of extent tree by the
141 * fact that truncate code waits for all DIO to finish (thus exclusion from
142 * direct IO is achieved) and also waits for PageWriteback bits. Thus we
143 * cannot get to ext4_ext_truncate() before all IOs overlapping that range are
144 * completed (happens from ext4_free_ioend()).
146 static int ext4_end_io(ext4_io_end_t *io)
148 struct inode *inode = io->inode;
149 loff_t offset = io->offset;
150 ssize_t size = io->size;
151 handle_t *handle = io->handle;
154 ext4_debug("ext4_end_io_nolock: io 0x%p from inode %lu,list->next 0x%p,"
156 io, inode->i_ino, io->list.next, io->list.prev);
158 io->handle = NULL; /* Following call will use up the handle */
159 ret = ext4_convert_unwritten_extents(handle, inode, offset, size);
161 ext4_msg(inode->i_sb, KERN_EMERG,
162 "failed to convert unwritten extents to written "
163 "extents -- potential data loss! "
164 "(inode %lu, offset %llu, size %zd, error %d)",
165 inode->i_ino, offset, size, ret);
167 ext4_clear_io_unwritten_flag(io);
168 ext4_release_io_end(io);
172 static void dump_completed_IO(struct inode *inode, struct list_head *head)
175 struct list_head *cur, *before, *after;
176 ext4_io_end_t *io, *io0, *io1;
178 if (list_empty(head))
181 ext4_debug("Dump inode %lu completed io list\n", inode->i_ino);
182 list_for_each_entry(io, head, list) {
185 io0 = container_of(before, ext4_io_end_t, list);
187 io1 = container_of(after, ext4_io_end_t, list);
189 ext4_debug("io 0x%p from inode %lu,prev 0x%p,next 0x%p\n",
190 io, inode->i_ino, io0, io1);
195 /* Add the io_end to per-inode completed end_io list. */
196 static void ext4_add_complete_io(ext4_io_end_t *io_end)
198 struct ext4_inode_info *ei = EXT4_I(io_end->inode);
199 struct ext4_sb_info *sbi = EXT4_SB(io_end->inode->i_sb);
200 struct workqueue_struct *wq;
203 /* Only reserved conversions from writeback should enter here */
204 WARN_ON(!(io_end->flag & EXT4_IO_END_UNWRITTEN));
205 WARN_ON(!io_end->handle && sbi->s_journal);
206 spin_lock_irqsave(&ei->i_completed_io_lock, flags);
207 wq = sbi->rsv_conversion_wq;
208 if (list_empty(&ei->i_rsv_conversion_list))
209 queue_work(wq, &ei->i_rsv_conversion_work);
210 list_add_tail(&io_end->list, &ei->i_rsv_conversion_list);
211 spin_unlock_irqrestore(&ei->i_completed_io_lock, flags);
214 static int ext4_do_flush_completed_IO(struct inode *inode,
215 struct list_head *head)
218 struct list_head unwritten;
220 struct ext4_inode_info *ei = EXT4_I(inode);
223 spin_lock_irqsave(&ei->i_completed_io_lock, flags);
224 dump_completed_IO(inode, head);
225 list_replace_init(head, &unwritten);
226 spin_unlock_irqrestore(&ei->i_completed_io_lock, flags);
228 while (!list_empty(&unwritten)) {
229 io = list_entry(unwritten.next, ext4_io_end_t, list);
230 BUG_ON(!(io->flag & EXT4_IO_END_UNWRITTEN));
231 list_del_init(&io->list);
233 err = ext4_end_io(io);
234 if (unlikely(!ret && err))
241 * work on completed IO, to convert unwritten extents to extents
243 void ext4_end_io_rsv_work(struct work_struct *work)
245 struct ext4_inode_info *ei = container_of(work, struct ext4_inode_info,
246 i_rsv_conversion_work);
247 ext4_do_flush_completed_IO(&ei->vfs_inode, &ei->i_rsv_conversion_list);
250 ext4_io_end_t *ext4_init_io_end(struct inode *inode, gfp_t flags)
252 ext4_io_end_t *io = kmem_cache_zalloc(io_end_cachep, flags);
254 atomic_inc(&EXT4_I(inode)->i_ioend_count);
256 INIT_LIST_HEAD(&io->list);
257 atomic_set(&io->count, 1);
262 void ext4_put_io_end_defer(ext4_io_end_t *io_end)
264 if (atomic_dec_and_test(&io_end->count)) {
265 if (!(io_end->flag & EXT4_IO_END_UNWRITTEN) || !io_end->size) {
266 ext4_release_io_end(io_end);
269 ext4_add_complete_io(io_end);
273 int ext4_put_io_end(ext4_io_end_t *io_end)
277 if (atomic_dec_and_test(&io_end->count)) {
278 if (io_end->flag & EXT4_IO_END_UNWRITTEN) {
279 err = ext4_convert_unwritten_extents(io_end->handle,
280 io_end->inode, io_end->offset,
282 io_end->handle = NULL;
283 ext4_clear_io_unwritten_flag(io_end);
285 ext4_release_io_end(io_end);
290 ext4_io_end_t *ext4_get_io_end(ext4_io_end_t *io_end)
292 atomic_inc(&io_end->count);
296 /* BIO completion function for page writeback */
297 static void ext4_end_bio(struct bio *bio, int error)
299 ext4_io_end_t *io_end = bio->bi_private;
300 sector_t bi_sector = bio->bi_iter.bi_sector;
303 bio->bi_end_io = NULL;
304 if (test_bit(BIO_UPTODATE, &bio->bi_flags))
308 struct inode *inode = io_end->inode;
310 ext4_warning(inode->i_sb, "I/O error %d writing to inode %lu "
311 "(offset %llu size %ld starting block %llu)",
313 (unsigned long long) io_end->offset,
316 bi_sector >> (inode->i_blkbits - 9));
317 mapping_set_error(inode->i_mapping, error);
320 if (io_end->flag & EXT4_IO_END_UNWRITTEN) {
322 * Link bio into list hanging from io_end. We have to do it
323 * atomically as bio completions can be racing against each
326 bio->bi_private = xchg(&io_end->bio, bio);
327 ext4_put_io_end_defer(io_end);
330 * Drop io_end reference early. Inode can get freed once
333 ext4_put_io_end_defer(io_end);
334 ext4_finish_bio(bio);
339 void ext4_io_submit(struct ext4_io_submit *io)
341 struct bio *bio = io->io_bio;
345 submit_bio(io->io_op, io->io_bio);
346 BUG_ON(bio_flagged(io->io_bio, BIO_EOPNOTSUPP));
352 void ext4_io_submit_init(struct ext4_io_submit *io,
353 struct writeback_control *wbc)
355 io->io_op = (wbc->sync_mode == WB_SYNC_ALL ? WRITE_SYNC : WRITE);
360 static int io_submit_init_bio(struct ext4_io_submit *io,
361 struct buffer_head *bh)
363 int nvecs = bio_get_nr_vecs(bh->b_bdev);
366 bio = bio_alloc(GFP_NOIO, min(nvecs, BIO_MAX_PAGES));
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);
374 io->io_next_block = bh->b_blocknr;
378 static int io_submit_add_bh(struct ext4_io_submit *io,
380 struct buffer_head *bh)
384 if (io->io_bio && bh->b_blocknr != io->io_next_block) {
388 if (io->io_bio == NULL) {
389 ret = io_submit_init_bio(io, bh);
393 ret = bio_add_page(io->io_bio, bh->b_page, bh->b_size, bh_offset(bh));
394 if (ret != bh->b_size)
395 goto submit_and_retry;
400 int ext4_bio_write_page(struct ext4_io_submit *io,
403 struct writeback_control *wbc,
406 struct inode *inode = page->mapping->host;
407 unsigned block_start, blocksize;
408 struct buffer_head *bh, *head;
410 int nr_submitted = 0;
412 blocksize = 1 << inode->i_blkbits;
414 BUG_ON(!PageLocked(page));
415 BUG_ON(PageWriteback(page));
418 set_page_writeback_keepwrite(page);
420 set_page_writeback(page);
421 ClearPageError(page);
424 * Comments copied from block_write_full_page:
426 * The page straddles i_size. It must be zeroed out on each and every
427 * writepage invocation because it may be mmapped. "A file is mapped
428 * in multiples of the page size. For a file that is not a multiple of
429 * the page size, the remaining memory is zeroed when mapped, and
430 * writes to that region are not written out to the file."
432 if (len < PAGE_CACHE_SIZE)
433 zero_user_segment(page, len, PAGE_CACHE_SIZE);
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
441 bh = head = page_buffers(page);
443 block_start = bh_offset(bh);
444 if (block_start >= len) {
445 clear_buffer_dirty(bh);
446 set_buffer_uptodate(bh);
449 if (!buffer_dirty(bh) || buffer_delay(bh) ||
450 !buffer_mapped(bh) || buffer_unwritten(bh)) {
451 /* A hole? We can safely clear the dirty bit */
452 if (!buffer_mapped(bh))
453 clear_buffer_dirty(bh);
458 if (buffer_new(bh)) {
459 clear_buffer_new(bh);
460 unmap_underlying_metadata(bh->b_bdev, bh->b_blocknr);
462 set_buffer_async_write(bh);
463 } while ((bh = bh->b_this_page) != head);
465 /* Now submit buffers to write */
466 bh = head = page_buffers(page);
468 if (!buffer_async_write(bh))
470 ret = io_submit_add_bh(io, inode, bh);
473 * We only get here on ENOMEM. Not much else
474 * we can do but mark the page as dirty, and
475 * better luck next time.
477 redirty_page_for_writepage(wbc, page);
481 clear_buffer_dirty(bh);
482 } while ((bh = bh->b_this_page) != head);
484 /* Error stopped previous loop? Clean up buffers... */
487 clear_buffer_async_write(bh);
488 bh = bh->b_this_page;
489 } while (bh != head);
492 /* Nothing submitted - we have to end page writeback */
494 end_page_writeback(page);