[linux-2.6-block.git] / fs / ext4 / page-io.c

/*
 * linux/fs/ext4/page-io.c
 *
 * This contains the new page_io functions for ext4
 *
 * Written by Theodore Ts'o, 2010.
 */

#include <linux/fs.h>
#include <linux/time.h>
#include <linux/jbd2.h>
#include <linux/highuid.h>
#include <linux/pagemap.h>
#include <linux/quotaops.h>
#include <linux/string.h>
#include <linux/buffer_head.h>
#include <linux/writeback.h>
#include <linux/pagevec.h>
#include <linux/mpage.h>
#include <linux/namei.h>
#include <linux/uio.h>
#include <linux/bio.h>
#include <linux/workqueue.h>
#include <linux/kernel.h>
#include <linux/slab.h>

#include "ext4_jbd2.h"
#include "xattr.h"
#include "acl.h"
#include "ext4_extents.h"

static struct kmem_cache *io_page_cachep, *io_end_cachep;

int __init ext4_init_pageio(void)
{
	io_page_cachep = KMEM_CACHE(ext4_io_page, SLAB_RECLAIM_ACCOUNT);
	if (io_page_cachep == NULL)
		return -ENOMEM;
	io_end_cachep = KMEM_CACHE(ext4_io_end, SLAB_RECLAIM_ACCOUNT);
	if (io_end_cachep == NULL) {
		kmem_cache_destroy(io_page_cachep);
		return -ENOMEM;
	}
	return 0;
}

void ext4_exit_pageio(void)
{
	kmem_cache_destroy(io_end_cachep);
	kmem_cache_destroy(io_page_cachep);
}

void ext4_ioend_wait(struct inode *inode)
{
	wait_queue_head_t *wq = ext4_ioend_wq(inode);

	wait_event(*wq, (atomic_read(&EXT4_I(inode)->i_ioend_count) == 0));
}

static void put_io_page(struct ext4_io_page *io_page)
{
	if (atomic_dec_and_test(&io_page->p_count)) {
		end_page_writeback(io_page->p_page);
		put_page(io_page->p_page);
		kmem_cache_free(io_page_cachep, io_page);
	}
}

void ext4_free_io_end(ext4_io_end_t *io)
{
	int i;

	BUG_ON(!io);
	if (io->page)
		put_page(io->page);
	for (i = 0; i < io->num_io_pages; i++)
		put_io_page(io->pages[i]);
	io->num_io_pages = 0;
	if (atomic_dec_and_test(&EXT4_I(io->inode)->i_ioend_count))
		wake_up_all(ext4_ioend_wq(io->inode));
	kmem_cache_free(io_end_cachep, io);
}

/*
 * check a range of space and convert unwritten extents to written.
 *
 * Called with inode->i_mutex; we depend on this when we manipulate
 * io->flag, since we could otherwise race with ext4_flush_completed_IO()
 */
int ext4_end_io_nolock(ext4_io_end_t *io)
{
	struct inode *inode = io->inode;
	loff_t offset = io->offset;
	ssize_t size = io->size;
	int ret = 0;

	ext4_debug("ext4_end_io_nolock: io 0x%p from inode %lu,list->next 0x%p,"
		   "list->prev 0x%p\n",
		   io, inode->i_ino, io->list.next, io->list.prev);

	ret = ext4_convert_unwritten_extents(inode, offset, size);
	if (ret < 0) {
		ext4_msg(inode->i_sb, KERN_EMERG,
			 "failed to convert unwritten extents to written "
			 "extents -- potential data loss!  "
			 "(inode %lu, offset %llu, size %zd, error %d)",
			 inode->i_ino, offset, size, ret);
	}

	if (io->iocb)
		aio_complete(io->iocb, io->result, 0);

	/* Wake up anyone waiting on unwritten extent conversion */
	if (atomic_dec_and_test(&EXT4_I(inode)->i_aiodio_unwritten))
		wake_up_all(ext4_ioend_wq(io->inode));
	return ret;
}

/*
 * work on completed aio dio IO, to convert unwritten extents to extents
 */
static void ext4_end_io_work(struct work_struct *work)
{
	ext4_io_end_t		*io = container_of(work, ext4_io_end_t, work);
	struct inode		*inode = io->inode;
	struct ext4_inode_info	*ei = EXT4_I(inode);
	unsigned long		flags;

	spin_lock_irqsave(&ei->i_completed_io_lock, flags);
	if (list_empty(&io->list)) {
		spin_unlock_irqrestore(&ei->i_completed_io_lock, flags);
		goto free;
	}

	if (!mutex_trylock(&inode->i_mutex)) {
		spin_unlock_irqrestore(&ei->i_completed_io_lock, flags);
		/*
		 * Requeue the work instead of waiting so that the work
		 * items queued after this can be processed.
		 */
		queue_work(EXT4_SB(inode->i_sb)->dio_unwritten_wq, &io->work);
		/*
		 * To prevent the ext4-dio-unwritten thread from keeping
		 * requeueing end_io requests and occupying cpu for too long,
		 * yield the cpu if it sees an end_io request that has already
		 * been requeued.
		 */
		if (io->flag & EXT4_IO_END_QUEUED)
			yield();
		io->flag |= EXT4_IO_END_QUEUED;
		return;
	}
	list_del_init(&io->list);
	spin_unlock_irqrestore(&ei->i_completed_io_lock, flags);
	(void) ext4_end_io_nolock(io);
	mutex_unlock(&inode->i_mutex);
free:
	ext4_free_io_end(io);
}

ext4_io_end_t *ext4_init_io_end(struct inode *inode, gfp_t flags)
{
	ext4_io_end_t *io = kmem_cache_zalloc(io_end_cachep, flags);
	if (io) {
		atomic_inc(&EXT4_I(inode)->i_ioend_count);
		io->inode = inode;
		INIT_WORK(&io->work, ext4_end_io_work);
		INIT_LIST_HEAD(&io->list);
	}
	return io;
}

/*
 * Print an buffer I/O error compatible with the fs/buffer.c.  This
 * provides compatibility with dmesg scrapers that look for a specific
 * buffer I/O error message.  We really need a unified error reporting
 * structure to userspace ala Digital Unix's uerf system, but it's
 * probably not going to happen in my lifetime, due to LKML politics...
 */
static void buffer_io_error(struct buffer_head *bh)
{
	char b[BDEVNAME_SIZE];
	printk(KERN_ERR "Buffer I/O error on device %s, logical block %llu\n",
			bdevname(bh->b_bdev, b),
			(unsigned long long)bh->b_blocknr);
}

static void ext4_end_bio(struct bio *bio, int error)
{
	ext4_io_end_t *io_end = bio->bi_private;
	struct workqueue_struct *wq;
	struct inode *inode;
	unsigned long flags;
	int i;
	sector_t bi_sector = bio->bi_sector;

	BUG_ON(!io_end);
	bio->bi_private = NULL;
	bio->bi_end_io = NULL;
	if (test_bit(BIO_UPTODATE, &bio->bi_flags))
		error = 0;
	bio_put(bio);

	for (i = 0; i < io_end->num_io_pages; i++) {
		struct page *page = io_end->pages[i]->p_page;
		struct buffer_head *bh, *head;
		loff_t offset;
		loff_t io_end_offset;

		if (error) {
			SetPageError(page);
			set_bit(AS_EIO, &page->mapping->flags);
			head = page_buffers(page);
			BUG_ON(!head);

			io_end_offset = io_end->offset + io_end->size;

			offset = (sector_t) page->index << PAGE_CACHE_SHIFT;
			bh = head;
			do {
				if ((offset >= io_end->offset) &&
				    (offset+bh->b_size <= io_end_offset))
					buffer_io_error(bh);

				offset += bh->b_size;
				bh = bh->b_this_page;
			} while (bh != head);
		}

		put_io_page(io_end->pages[i]);
	}
	io_end->num_io_pages = 0;
	inode = io_end->inode;

	if (error) {
		io_end->flag |= EXT4_IO_END_ERROR;
		ext4_warning(inode->i_sb, "I/O error writing to inode %lu "
			     "(offset %llu size %ld starting block %llu)",
			     inode->i_ino,
			     (unsigned long long) io_end->offset,
			     (long) io_end->size,
			     (unsigned long long)
			     bi_sector >> (inode->i_blkbits - 9));
	}

	if (!(io_end->flag & EXT4_IO_END_UNWRITTEN)) {
		ext4_free_io_end(io_end);
		return;
	}

	/* Add the io_end to per-inode completed io list*/
	spin_lock_irqsave(&EXT4_I(inode)->i_completed_io_lock, flags);
	list_add_tail(&io_end->list, &EXT4_I(inode)->i_completed_io_list);
	spin_unlock_irqrestore(&EXT4_I(inode)->i_completed_io_lock, flags);

	wq = EXT4_SB(inode->i_sb)->dio_unwritten_wq;
	/* queue the work to convert unwritten extents to written */
	queue_work(wq, &io_end->work);
}

void ext4_io_submit(struct ext4_io_submit *io)
{
	struct bio *bio = io->io_bio;

	if (bio) {
		bio_get(io->io_bio);
		submit_bio(io->io_op, io->io_bio);
		BUG_ON(bio_flagged(io->io_bio, BIO_EOPNOTSUPP));
		bio_put(io->io_bio);
	}
	io->io_bio = NULL;
	io->io_op = 0;
	io->io_end = NULL;
}

static int io_submit_init(struct ext4_io_submit *io,
			  struct inode *inode,
			  struct writeback_control *wbc,
			  struct buffer_head *bh)
{
	ext4_io_end_t *io_end;
	struct page *page = bh->b_page;
	int nvecs = bio_get_nr_vecs(bh->b_bdev);
	struct bio *bio;

	io_end = ext4_init_io_end(inode, GFP_NOFS);
	if (!io_end)
		return -ENOMEM;
	bio = bio_alloc(GFP_NOIO, min(nvecs, BIO_MAX_PAGES));
	bio->bi_sector = bh->b_blocknr * (bh->b_size >> 9);
	bio->bi_bdev = bh->b_bdev;
	bio->bi_private = io->io_end = io_end;
	bio->bi_end_io = ext4_end_bio;

	io_end->offset = (page->index << PAGE_CACHE_SHIFT) + bh_offset(bh);

	io->io_bio = bio;
	io->io_op = (wbc->sync_mode == WB_SYNC_ALL ?  WRITE_SYNC : WRITE);
	io->io_next_block = bh->b_blocknr;
	return 0;
}

static int io_submit_add_bh(struct ext4_io_submit *io,
			    struct ext4_io_page *io_page,
			    struct inode *inode,
			    struct writeback_control *wbc,
			    struct buffer_head *bh)
{
	ext4_io_end_t *io_end;
	int ret;

	if (buffer_new(bh)) {
		clear_buffer_new(bh);
		unmap_underlying_metadata(bh->b_bdev, bh->b_blocknr);
	}

	if (!buffer_mapped(bh) || buffer_delay(bh)) {
		if (!buffer_mapped(bh))
			clear_buffer_dirty(bh);
		if (io->io_bio)
			ext4_io_submit(io);
		return 0;
	}

	if (io->io_bio && bh->b_blocknr != io->io_next_block) {
submit_and_retry:
		ext4_io_submit(io);
	}
	if (io->io_bio == NULL) {
		ret = io_submit_init(io, inode, wbc, bh);
		if (ret)
			return ret;
	}
	io_end = io->io_end;
	if ((io_end->num_io_pages >= MAX_IO_PAGES) &&
	    (io_end->pages[io_end->num_io_pages-1] != io_page))
		goto submit_and_retry;
	if (buffer_uninit(bh))
		ext4_set_io_unwritten_flag(inode, io_end);
	io->io_end->size += bh->b_size;
	io->io_next_block++;
	ret = bio_add_page(io->io_bio, bh->b_page, bh->b_size, bh_offset(bh));
	if (ret != bh->b_size)
		goto submit_and_retry;
	if ((io_end->num_io_pages == 0) ||
	    (io_end->pages[io_end->num_io_pages-1] != io_page)) {
		io_end->pages[io_end->num_io_pages++] = io_page;
		atomic_inc(&io_page->p_count);
	}
	return 0;
}

int ext4_bio_write_page(struct ext4_io_submit *io,
			struct page *page,
			int len,
			struct writeback_control *wbc)
{
	struct inode *inode = page->mapping->host;
	unsigned block_start, block_end, blocksize;
	struct ext4_io_page *io_page;
	struct buffer_head *bh, *head;
	int ret = 0;

	blocksize = 1 << inode->i_blkbits;

	BUG_ON(!PageLocked(page));
	BUG_ON(PageWriteback(page));

	io_page = kmem_cache_alloc(io_page_cachep, GFP_NOFS);
	if (!io_page) {
		set_page_dirty(page);
		unlock_page(page);
		return -ENOMEM;
	}
	io_page->p_page = page;
	atomic_set(&io_page->p_count, 1);
	get_page(page);
	set_page_writeback(page);
	ClearPageError(page);

	for (bh = head = page_buffers(page), block_start = 0;
	     bh != head || !block_start;
	     block_start = block_end, bh = bh->b_this_page) {

		block_end = block_start + blocksize;
		if (block_start >= len) {
			clear_buffer_dirty(bh);
			set_buffer_uptodate(bh);
			continue;
		}
		clear_buffer_dirty(bh);
		ret = io_submit_add_bh(io, io_page, inode, wbc, bh);
		if (ret) {
			/*
			 * We only get here on ENOMEM.  Not much else
			 * we can do but mark the page as dirty, and
			 * better luck next time.
			 */
			set_page_dirty(page);
			break;
		}
	}
	unlock_page(page);
	/*
	 * If the page was truncated before we could do the writeback,
	 * or we had a memory allocation error while trying to write
	 * the first buffer head, we won't have submitted any pages for
	 * I/O.  In that case we need to make sure we've cleared the
	 * PageWriteback bit from the page to prevent the system from
	 * wedging later on.
	 */
	put_io_page(io_page);
	return ret;
}
Commit	Line	Data
bd2d0210 TT	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
bd2d0210 TT	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
5dabfc78	34	int __init ext4_init_pageio(void)
bd2d0210 TT	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);
13195184	40	if (io_end_cachep == NULL) {
bd2d0210 TT	41	kmem_cache_destroy(io_page_cachep);
	42	return -ENOMEM;
	43	}
bd2d0210 TT	44	return 0;
	45	}
	46
5dabfc78	47	void ext4_exit_pageio(void)
bd2d0210 TT	48	{
	49	kmem_cache_destroy(io_end_cachep);
	50	kmem_cache_destroy(io_page_cachep);
	51	}
	52
f7ad6d2e TT	53	void ext4_ioend_wait(struct inode *inode)
f7ad6d2e TT	54	{
e9e3bcec	55	wait_queue_head_t *wq = ext4_ioend_wq(inode);
f7ad6d2e TT	56
	57	wait_event(*wq, (atomic_read(&EXT4_I(inode)->i_ioend_count) == 0));
	58	}
	59
83668e71 TT	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
bd2d0210 TT	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);
83668e71 TT	76	for (i = 0; i < io->num_io_pages; i++)
83668e71 TT	77	put_io_page(io->pages[i]);
bd2d0210	78	io->num_io_pages = 0;
4e298021 TT	79	if (atomic_dec_and_test(&EXT4_I(io->inode)->i_ioend_count))
4e298021 TT	80	wake_up_all(ext4_ioend_wq(io->inode));
bd2d0210 TT	81	kmem_cache_free(io_end_cachep, io);
	82	}
	83
	84	/*
	85	* check a range of space and convert unwritten extents to written.
d73d5046 TM	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()
bd2d0210 TT	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
bd2d0210 TT	101	ret = ext4_convert_unwritten_extents(inode, offset, size);
bd2d0210 TT	102	if (ret < 0) {
b82e384c TT	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);
bd2d0210 TT	108	}
	109
	110	if (io->iocb)
	111	aio_complete(io->iocb, io->result, 0);
e9e3bcec	112
b82e384c TT	113	/* Wake up anyone waiting on unwritten extent conversion */
	114	if (atomic_dec_and_test(&EXT4_I(inode)->i_aiodio_unwritten))
	115	wake_up_all(ext4_ioend_wq(io->inode));
bd2d0210 TT	116	return ret;
	117	}
	118
	119	/*
	120	* work on completed aio dio IO, to convert unwritten extents to extents
	121	*/
	122	static void ext4_end_io_work(struct work_struct *work)
	123	{
	124	ext4_io_end_t *io = container_of(work, ext4_io_end_t, work);
	125	struct inode *inode = io->inode;
	126	struct ext4_inode_info *ei = EXT4_I(inode);
	127	unsigned long flags;
bd2d0210	128
d73d5046 TM	129	spin_lock_irqsave(&ei->i_completed_io_lock, flags);
	130	if (list_empty(&io->list)) {
	131	spin_unlock_irqrestore(&ei->i_completed_io_lock, flags);
	132	goto free;
	133	}
d73d5046	134
8c0bec21	135	if (!mutex_trylock(&inode->i_mutex)) {
b82e384c	136	spin_unlock_irqrestore(&ei->i_completed_io_lock, flags);
8c0bec21 JZ	137	/*
	138	* Requeue the work instead of waiting so that the work
	139	* items queued after this can be processed.
	140	*/
	141	queue_work(EXT4_SB(inode->i_sb)->dio_unwritten_wq, &io->work);
	142	/*
	143	* To prevent the ext4-dio-unwritten thread from keeping
	144	* requeueing end_io requests and occupying cpu for too long,
	145	* yield the cpu if it sees an end_io request that has already
	146	* been requeued.
	147	*/
	148	if (io->flag & EXT4_IO_END_QUEUED)
	149	yield();
	150	io->flag \|= EXT4_IO_END_QUEUED;
	151	return;
	152	}
b82e384c	153	list_del_init(&io->list);
bd2d0210	154	spin_unlock_irqrestore(&ei->i_completed_io_lock, flags);
b82e384c	155	(void) ext4_end_io_nolock(io);
bd2d0210	156	mutex_unlock(&inode->i_mutex);
d73d5046	157	free:
bd2d0210 TT	158	ext4_free_io_end(io);
	159	}
	160
	161	ext4_io_end_t ext4_init_io_end(struct inode inode, gfp_t flags)
	162	{
b17b35ec	163	ext4_io_end_t *io = kmem_cache_zalloc(io_end_cachep, flags);
bd2d0210	164	if (io) {
f7ad6d2e TT	165	atomic_inc(&EXT4_I(inode)->i_ioend_count);
f7ad6d2e TT	166	io->inode = inode;
bd2d0210 TT	167	INIT_WORK(&io->work, ext4_end_io_work);
	168	INIT_LIST_HEAD(&io->list);
	169	}
	170	return io;
	171	}
	172
	173	/*
	174	* Print an buffer I/O error compatible with the fs/buffer.c. This
	175	* provides compatibility with dmesg scrapers that look for a specific
	176	* buffer I/O error message. We really need a unified error reporting
	177	* structure to userspace ala Digital Unix's uerf system, but it's
	178	* probably not going to happen in my lifetime, due to LKML politics...
	179	*/
	180	static void buffer_io_error(struct buffer_head *bh)
	181	{
	182	char b[BDEVNAME_SIZE];
	183	printk(KERN_ERR "Buffer I/O error on device %s, logical block %llu\n",
	184	bdevname(bh->b_bdev, b),
	185	(unsigned long long)bh->b_blocknr);
	186	}
	187
	188	static void ext4_end_bio(struct bio *bio, int error)
	189	{
	190	ext4_io_end_t *io_end = bio->bi_private;
	191	struct workqueue_struct *wq;
	192	struct inode *inode;
	193	unsigned long flags;
bd2d0210	194	int i;
d50bdd5a	195	sector_t bi_sector = bio->bi_sector;
bd2d0210 TT	196
bd2d0210 TT	197	BUG_ON(!io_end);
bd2d0210 TT	198	bio->bi_private = NULL;
	199	bio->bi_end_io = NULL;
	200	if (test_bit(BIO_UPTODATE, &bio->bi_flags))
	201	error = 0;
bd2d0210 TT	202	bio_put(bio);
bd2d0210 TT	203
bd2d0210 TT	204	for (i = 0; i < io_end->num_io_pages; i++) {
	205	struct page *page = io_end->pages[i]->p_page;
	206	struct buffer_head bh, head;
39db00f1 CW	207	loff_t offset;
39db00f1 CW	208	loff_t io_end_offset;
bd2d0210	209
39db00f1	210	if (error) {
bd2d0210	211	SetPageError(page);
39db00f1 CW	212	set_bit(AS_EIO, &page->mapping->flags);
	213	head = page_buffers(page);
	214	BUG_ON(!head);
	215
	216	io_end_offset = io_end->offset + io_end->size;
bd2d0210 TT	217
	218	offset = (sector_t) page->index << PAGE_CACHE_SHIFT;
	219	bh = head;
	220	do {
	221	if ((offset >= io_end->offset) &&
39db00f1 CW	222	(offset+bh->b_size <= io_end_offset))
	223	buffer_io_error(bh);
	224
bd2d0210 TT	225	offset += bh->b_size;
	226	bh = bh->b_this_page;
	227	} while (bh != head);
	228	}
	229
08da1193	230	put_io_page(io_end->pages[i]);
bd2d0210	231	}
bd2d0210	232	io_end->num_io_pages = 0;
f7ad6d2e TT	233	inode = io_end->inode;
	234
	235	if (error) {
	236	io_end->flag \|= EXT4_IO_END_ERROR;
	237	ext4_warning(inode->i_sb, "I/O error writing to inode %lu "
	238	"(offset %llu size %ld starting block %llu)",
	239	inode->i_ino,
	240	(unsigned long long) io_end->offset,
	241	(long) io_end->size,
	242	(unsigned long long)
d50bdd5a	243	bi_sector >> (inode->i_blkbits - 9));
f7ad6d2e	244	}
bd2d0210	245
b6168443 TT	246	if (!(io_end->flag & EXT4_IO_END_UNWRITTEN)) {
	247	ext4_free_io_end(io_end);
	248	return;
	249	}
	250
bd2d0210 TT	251	/* Add the io_end to per-inode completed io list*/
	252	spin_lock_irqsave(&EXT4_I(inode)->i_completed_io_lock, flags);
	253	list_add_tail(&io_end->list, &EXT4_I(inode)->i_completed_io_list);
	254	spin_unlock_irqrestore(&EXT4_I(inode)->i_completed_io_lock, flags);
	255
	256	wq = EXT4_SB(inode->i_sb)->dio_unwritten_wq;
	257	/* queue the work to convert unwritten extents to written */
	258	queue_work(wq, &io_end->work);
	259	}
	260
	261	void ext4_io_submit(struct ext4_io_submit *io)
	262	{
	263	struct bio *bio = io->io_bio;
	264
	265	if (bio) {
	266	bio_get(io->io_bio);
	267	submit_bio(io->io_op, io->io_bio);
	268	BUG_ON(bio_flagged(io->io_bio, BIO_EOPNOTSUPP));
	269	bio_put(io->io_bio);
	270	}
7dc57615	271	io->io_bio = NULL;
bd2d0210	272	io->io_op = 0;
7dc57615	273	io->io_end = NULL;
bd2d0210 TT	274	}
	275
	276	static int io_submit_init(struct ext4_io_submit *io,
	277	struct inode *inode,
	278	struct writeback_control *wbc,
	279	struct buffer_head *bh)
	280	{
	281	ext4_io_end_t *io_end;
	282	struct page *page = bh->b_page;
	283	int nvecs = bio_get_nr_vecs(bh->b_bdev);
	284	struct bio *bio;
	285
	286	io_end = ext4_init_io_end(inode, GFP_NOFS);
	287	if (!io_end)
	288	return -ENOMEM;
275d3ba6	289	bio = bio_alloc(GFP_NOIO, min(nvecs, BIO_MAX_PAGES));
bd2d0210 TT	290	bio->bi_sector = bh->b_blocknr * (bh->b_size >> 9);
	291	bio->bi_bdev = bh->b_bdev;
	292	bio->bi_private = io->io_end = io_end;
	293	bio->bi_end_io = ext4_end_bio;
	294
bd2d0210 TT	295	io_end->offset = (page->index << PAGE_CACHE_SHIFT) + bh_offset(bh);
	296
	297	io->io_bio = bio;
721a9602	298	io->io_op = (wbc->sync_mode == WB_SYNC_ALL ? WRITE_SYNC : WRITE);
bd2d0210 TT	299	io->io_next_block = bh->b_blocknr;
	300	return 0;
	301	}
	302
	303	static int io_submit_add_bh(struct ext4_io_submit *io,
	304	struct ext4_io_page *io_page,
	305	struct inode *inode,
	306	struct writeback_control *wbc,
	307	struct buffer_head *bh)
	308	{
	309	ext4_io_end_t *io_end;
	310	int ret;
	311
	312	if (buffer_new(bh)) {
	313	clear_buffer_new(bh);
	314	unmap_underlying_metadata(bh->b_bdev, bh->b_blocknr);
	315	}
	316
	317	if (!buffer_mapped(bh) \|\| buffer_delay(bh)) {
	318	if (!buffer_mapped(bh))
	319	clear_buffer_dirty(bh);
	320	if (io->io_bio)
	321	ext4_io_submit(io);
	322	return 0;
	323	}
	324
	325	if (io->io_bio && bh->b_blocknr != io->io_next_block) {
	326	submit_and_retry:
	327	ext4_io_submit(io);
	328	}
	329	if (io->io_bio == NULL) {
	330	ret = io_submit_init(io, inode, wbc, bh);
	331	if (ret)
	332	return ret;
	333	}
	334	io_end = io->io_end;
	335	if ((io_end->num_io_pages >= MAX_IO_PAGES) &&
	336	(io_end->pages[io_end->num_io_pages-1] != io_page))
	337	goto submit_and_retry;
0edeb71d TM	338	if (buffer_uninit(bh))
0edeb71d TM	339	ext4_set_io_unwritten_flag(inode, io_end);
bd2d0210 TT	340	io->io_end->size += bh->b_size;
	341	io->io_next_block++;
	342	ret = bio_add_page(io->io_bio, bh->b_page, bh->b_size, bh_offset(bh));
	343	if (ret != bh->b_size)
	344	goto submit_and_retry;
	345	if ((io_end->num_io_pages == 0) \|\|
	346	(io_end->pages[io_end->num_io_pages-1] != io_page)) {
	347	io_end->pages[io_end->num_io_pages++] = io_page;
83668e71	348	atomic_inc(&io_page->p_count);
bd2d0210 TT	349	}
	350	return 0;
	351	}
	352
	353	int ext4_bio_write_page(struct ext4_io_submit *io,
	354	struct page *page,
	355	int len,
	356	struct writeback_control *wbc)
	357	{
	358	struct inode *inode = page->mapping->host;
	359	unsigned block_start, block_end, blocksize;
	360	struct ext4_io_page *io_page;
	361	struct buffer_head bh, head;
	362	int ret = 0;
	363
	364	blocksize = 1 << inode->i_blkbits;
	365
d50bdd5a	366	BUG_ON(!PageLocked(page));
bd2d0210	367	BUG_ON(PageWriteback(page));
bd2d0210 TT	368
	369	io_page = kmem_cache_alloc(io_page_cachep, GFP_NOFS);
	370	if (!io_page) {
	371	set_page_dirty(page);
	372	unlock_page(page);
	373	return -ENOMEM;
	374	}
	375	io_page->p_page = page;
83668e71	376	atomic_set(&io_page->p_count, 1);
bd2d0210	377	get_page(page);
a54aa761 TT	378	set_page_writeback(page);
a54aa761 TT	379	ClearPageError(page);
bd2d0210 TT	380
	381	for (bh = head = page_buffers(page), block_start = 0;
	382	bh != head \|\| !block_start;
	383	block_start = block_end, bh = bh->b_this_page) {
d50bdd5a	384
bd2d0210 TT	385	block_end = block_start + blocksize;
	386	if (block_start >= len) {
	387	clear_buffer_dirty(bh);
	388	set_buffer_uptodate(bh);
	389	continue;
	390	}
d50bdd5a	391	clear_buffer_dirty(bh);
bd2d0210 TT	392	ret = io_submit_add_bh(io, io_page, inode, wbc, bh);
	393	if (ret) {
	394	/*
	395	* We only get here on ENOMEM. Not much else
	396	* we can do but mark the page as dirty, and
	397	* better luck next time.
	398	*/
	399	set_page_dirty(page);
	400	break;
	401	}
	402	}
	403	unlock_page(page);
	404	/*
	405	* If the page was truncated before we could do the writeback,
	406	* or we had a memory allocation error while trying to write
	407	* the first buffer head, we won't have submitted any pages for
	408	* I/O. In that case we need to make sure we've cleared the
	409	* PageWriteback bit from the page to prevent the system from
	410	* wedging later on.
	411	*/
83668e71	412	put_io_page(io_page);
bd2d0210 TT	413	return ret;
bd2d0210 TT	414	}