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 "ext4_jbd2.h"
30 #include "ext4_extents.h"
32 static struct kmem_cache *io_page_cachep, *io_end_cachep;
34 int __init ext4_init_pageio(void)
36 io_page_cachep = KMEM_CACHE(ext4_io_page, SLAB_RECLAIM_ACCOUNT);
37 if (io_page_cachep == NULL)
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);
47 void ext4_exit_pageio(void)
49 kmem_cache_destroy(io_end_cachep);
50 kmem_cache_destroy(io_page_cachep);
53 void ext4_ioend_wait(struct inode *inode)
55 wait_queue_head_t *wq = ext4_ioend_wq(inode);
57 wait_event(*wq, (atomic_read(&EXT4_I(inode)->i_ioend_count) == 0));
60 static void put_io_page(struct ext4_io_page *io_page)
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);
69 void ext4_free_io_end(ext4_io_end_t *io)
74 BUG_ON(!list_empty(&io->list));
75 BUG_ON(io->flag & EXT4_IO_END_UNWRITTEN);
79 for (i = 0; i < io->num_io_pages; i++)
80 put_io_page(io->pages[i]);
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);
87 /* check a range of space and convert unwritten extents to written. */
88 static int ext4_end_io(ext4_io_end_t *io)
90 struct inode *inode = io->inode;
91 loff_t offset = io->offset;
92 ssize_t size = io->size;
95 ext4_debug("ext4_end_io_nolock: io 0x%p from inode %lu,list->next 0x%p,"
97 io, inode->i_ino, io->list.next, io->list.prev);
99 ret = ext4_convert_unwritten_extents(inode, offset, size);
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);
108 aio_complete(io->iocb, io->result, 0);
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));
118 static void dump_completed_IO(struct inode *inode)
121 struct list_head *cur, *before, *after;
122 ext4_io_end_t *io, *io0, *io1;
125 if (list_empty(&EXT4_I(inode)->i_completed_io_list)) {
126 ext4_debug("inode %lu completed_io list is empty\n",
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) {
135 io0 = container_of(before, ext4_io_end_t, list);
137 io1 = container_of(after, ext4_io_end_t, list);
139 ext4_debug("io 0x%p from inode %lu,prev 0x%p,next 0x%p\n",
140 io, inode->i_ino, io0, io1);
145 /* Add the io_end to per-inode completed end_io list. */
146 void ext4_add_complete_io(ext4_io_end_t *io_end)
148 struct ext4_inode_info *ei = EXT4_I(io_end->inode);
149 struct workqueue_struct *wq;
152 BUG_ON(!(io_end->flag & EXT4_IO_END_UNWRITTEN));
153 wq = EXT4_SB(io_end->inode->i_sb)->dio_unwritten_wq;
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);
160 list_add_tail(&io_end->list, &ei->i_completed_io_list);
161 spin_unlock_irqrestore(&ei->i_completed_io_lock, flags);
164 static int ext4_do_flush_completed_IO(struct inode *inode,
165 ext4_io_end_t *work_io)
168 struct list_head unwritten, complete, to_free;
170 struct ext4_inode_info *ei = EXT4_I(inode);
173 INIT_LIST_HEAD(&complete);
174 INIT_LIST_HEAD(&to_free);
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);
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);
186 err = ext4_end_io(io);
187 if (unlikely(!ret && err))
190 list_add_tail(&io->list, &complete);
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);
201 list_move(&io->list, &to_free);
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 */
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);
210 spin_unlock_irqrestore(&ei->i_completed_io_lock, flags);
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);
221 * work on completed aio dio IO, to convert unwritten extents to extents
223 static void ext4_end_io_work(struct work_struct *work)
225 ext4_io_end_t *io = container_of(work, ext4_io_end_t, work);
226 ext4_do_flush_completed_IO(io->inode, io);
229 int ext4_flush_unwritten_io(struct inode *inode)
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);
239 ext4_io_end_t *ext4_init_io_end(struct inode *inode, gfp_t flags)
241 ext4_io_end_t *io = kmem_cache_zalloc(io_end_cachep, flags);
243 atomic_inc(&EXT4_I(inode)->i_ioend_count);
245 INIT_WORK(&io->work, ext4_end_io_work);
246 INIT_LIST_HEAD(&io->list);
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...
258 static void buffer_io_error(struct buffer_head *bh)
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);
266 static void ext4_end_bio(struct bio *bio, int error)
268 ext4_io_end_t *io_end = bio->bi_private;
271 sector_t bi_sector = bio->bi_sector;
274 bio->bi_private = NULL;
275 bio->bi_end_io = NULL;
276 if (test_bit(BIO_UPTODATE, &bio->bi_flags))
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;
284 loff_t io_end_offset;
288 set_bit(AS_EIO, &page->mapping->flags);
289 head = page_buffers(page);
292 io_end_offset = io_end->offset + io_end->size;
294 offset = (sector_t) page->index << PAGE_CACHE_SHIFT;
297 if ((offset >= io_end->offset) &&
298 (offset+bh->b_size <= io_end_offset))
301 offset += bh->b_size;
302 bh = bh->b_this_page;
303 } while (bh != head);
306 put_io_page(io_end->pages[i]);
308 io_end->num_io_pages = 0;
309 inode = io_end->inode;
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)",
316 (unsigned long long) io_end->offset,
319 bi_sector >> (inode->i_blkbits - 9));
322 if (!(io_end->flag & EXT4_IO_END_UNWRITTEN)) {
323 ext4_free_io_end(io_end);
327 ext4_add_complete_io(io_end);
330 void ext4_io_submit(struct ext4_io_submit *io)
332 struct bio *bio = io->io_bio;
336 submit_bio(io->io_op, io->io_bio);
337 BUG_ON(bio_flagged(io->io_bio, BIO_EOPNOTSUPP));
345 static int io_submit_init(struct ext4_io_submit *io,
347 struct writeback_control *wbc,
348 struct buffer_head *bh)
350 ext4_io_end_t *io_end;
351 struct page *page = bh->b_page;
352 int nvecs = bio_get_nr_vecs(bh->b_bdev);
355 io_end = ext4_init_io_end(inode, GFP_NOFS);
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;
364 io_end->offset = (page->index << PAGE_CACHE_SHIFT) + bh_offset(bh);
367 io->io_op = (wbc->sync_mode == WB_SYNC_ALL ? WRITE_SYNC : WRITE);
368 io->io_next_block = bh->b_blocknr;
372 static int io_submit_add_bh(struct ext4_io_submit *io,
373 struct ext4_io_page *io_page,
375 struct writeback_control *wbc,
376 struct buffer_head *bh)
378 ext4_io_end_t *io_end;
381 if (buffer_new(bh)) {
382 clear_buffer_new(bh);
383 unmap_underlying_metadata(bh->b_bdev, bh->b_blocknr);
386 if (!buffer_mapped(bh) || buffer_delay(bh)) {
387 if (!buffer_mapped(bh))
388 clear_buffer_dirty(bh);
394 if (io->io_bio && bh->b_blocknr != io->io_next_block) {
398 if (io->io_bio == NULL) {
399 ret = io_submit_init(io, inode, wbc, bh);
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;
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);
422 int ext4_bio_write_page(struct ext4_io_submit *io,
425 struct writeback_control *wbc)
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;
433 blocksize = 1 << inode->i_blkbits;
435 BUG_ON(!PageLocked(page));
436 BUG_ON(PageWriteback(page));
438 io_page = kmem_cache_alloc(io_page_cachep, GFP_NOFS);
440 set_page_dirty(page);
444 io_page->p_page = page;
445 atomic_set(&io_page->p_count, 1);
447 set_page_writeback(page);
448 ClearPageError(page);
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) {
454 block_end = block_start + blocksize;
455 if (block_start >= len) {
457 * Comments copied from block_write_full_page_endio:
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
467 zero_user_segment(page, block_start, block_end);
468 clear_buffer_dirty(bh);
469 set_buffer_uptodate(bh);
472 clear_buffer_dirty(bh);
473 ret = io_submit_add_bh(io, io_page, inode, wbc, bh);
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.
480 set_page_dirty(page);
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
493 put_io_page(io_page);