[deliverable/linux.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/module.h>
#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;
	wait_queue_head_t *wq;

	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;
	wq = ext4_ioend_wq(io->inode);
	if (atomic_dec_and_test(&EXT4_I(io->inode)->i_ioend_count) &&
	    waitqueue_active(wq))
		wake_up_all(wq);
	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;
	wait_queue_head_t *wq;
	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);

	if (!(io->flag & EXT4_IO_END_UNWRITTEN))
		return ret;

	ret = ext4_convert_unwritten_extents(inode, offset, size);
	if (ret < 0) {
		printk(KERN_EMERG "%s: failed to convert unwritten "
			"extents to written extents, error is %d "
			"io is still on inode %lu aio dio list\n",
		       __func__, ret, inode->i_ino);
		return ret;
	}

	if (io->iocb)
		aio_complete(io->iocb, io->result, 0);
	/* clear the DIO AIO unwritten flag */
	if (io->flag & EXT4_IO_END_UNWRITTEN) {
		io->flag &= ~EXT4_IO_END_UNWRITTEN;
		/* Wake up anyone waiting on unwritten extent conversion */
		wq = ext4_ioend_wq(io->inode);
		if (atomic_dec_and_test(&EXT4_I(inode)->i_aiodio_unwritten) &&
		    waitqueue_active(wq)) {
			wake_up_all(wq);
		}
	}

	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;
	int			ret;

	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;
	}
	spin_unlock_irqrestore(&ei->i_completed_io_lock, flags);

	if (!mutex_trylock(&inode->i_mutex)) {
		/*
		 * 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;
	}
	ret = ext4_end_io_nolock(io);
	if (ret < 0) {
		mutex_unlock(&inode->i_mutex);
		return;
	}

	spin_lock_irqsave(&ei->i_completed_io_lock, flags);
	if (!list_empty(&io->list))
		list_del_init(&io->list);
	spin_unlock_irqrestore(&ei->i_completed_io_lock, flags);
	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) && !(io_end->flag & EXT4_IO_END_UNWRITTEN)) {
		io_end->flag |= EXT4_IO_END_UNWRITTEN;
		atomic_inc(&EXT4_I(inode)->i_aiodio_unwritten);
	}
	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
	9	#include <linux/module.h>
	10	#include <linux/fs.h>
	11	#include <linux/time.h>
	12	#include <linux/jbd2.h>
	13	#include <linux/highuid.h>
	14	#include <linux/pagemap.h>
	15	#include <linux/quotaops.h>
	16	#include <linux/string.h>
	17	#include <linux/buffer_head.h>
	18	#include <linux/writeback.h>
	19	#include <linux/pagevec.h>
	20	#include <linux/mpage.h>
	21	#include <linux/namei.h>
	22	#include <linux/uio.h>
	23	#include <linux/bio.h>
	24	#include <linux/workqueue.h>
	25	#include <linux/kernel.h>
	26	#include <linux/slab.h>
	27
	28	#include "ext4_jbd2.h"
	29	#include "xattr.h"
	30	#include "acl.h"
	31	#include "ext4_extents.h"
	32
	33	static struct kmem_cache io_page_cachep, io_end_cachep;
	34
5dabfc78	35	int __init ext4_init_pageio(void)
bd2d0210 TT	36	{
	37	io_page_cachep = KMEM_CACHE(ext4_io_page, SLAB_RECLAIM_ACCOUNT);
	38	if (io_page_cachep == NULL)
	39	return -ENOMEM;
	40	io_end_cachep = KMEM_CACHE(ext4_io_end, SLAB_RECLAIM_ACCOUNT);
13195184	41	if (io_end_cachep == NULL) {
bd2d0210 TT	42	kmem_cache_destroy(io_page_cachep);
	43	return -ENOMEM;
	44	}
bd2d0210 TT	45	return 0;
	46	}
	47
5dabfc78	48	void ext4_exit_pageio(void)
bd2d0210 TT	49	{
	50	kmem_cache_destroy(io_end_cachep);
	51	kmem_cache_destroy(io_page_cachep);
	52	}
	53
f7ad6d2e TT	54	void ext4_ioend_wait(struct inode *inode)
f7ad6d2e TT	55	{
e9e3bcec	56	wait_queue_head_t *wq = ext4_ioend_wq(inode);
f7ad6d2e TT	57
	58	wait_event(*wq, (atomic_read(&EXT4_I(inode)->i_ioend_count) == 0));
	59	}
	60
83668e71 TT	61	static void put_io_page(struct ext4_io_page *io_page)
	62	{
	63	if (atomic_dec_and_test(&io_page->p_count)) {
	64	end_page_writeback(io_page->p_page);
	65	put_page(io_page->p_page);
	66	kmem_cache_free(io_page_cachep, io_page);
	67	}
	68	}
	69
bd2d0210 TT	70	void ext4_free_io_end(ext4_io_end_t *io)
	71	{
	72	int i;
f7ad6d2e	73	wait_queue_head_t *wq;
bd2d0210 TT	74
	75	BUG_ON(!io);
	76	if (io->page)
	77	put_page(io->page);
83668e71 TT	78	for (i = 0; i < io->num_io_pages; i++)
83668e71 TT	79	put_io_page(io->pages[i]);
bd2d0210	80	io->num_io_pages = 0;
e9e3bcec	81	wq = ext4_ioend_wq(io->inode);
f7ad6d2e TT	82	if (atomic_dec_and_test(&EXT4_I(io->inode)->i_ioend_count) &&
	83	waitqueue_active(wq))
	84	wake_up_all(wq);
bd2d0210 TT	85	kmem_cache_free(io_end_cachep, io);
	86	}
	87
	88	/*
	89	* check a range of space and convert unwritten extents to written.
d73d5046 TM	90	*
	91	* Called with inode->i_mutex; we depend on this when we manipulate
	92	* io->flag, since we could otherwise race with ext4_flush_completed_IO()
bd2d0210 TT	93	*/
	94	int ext4_end_io_nolock(ext4_io_end_t *io)
	95	{
	96	struct inode *inode = io->inode;
	97	loff_t offset = io->offset;
	98	ssize_t size = io->size;
e9e3bcec	99	wait_queue_head_t *wq;
bd2d0210 TT	100	int ret = 0;
	101
	102	ext4_debug("ext4_end_io_nolock: io 0x%p from inode %lu,list->next 0x%p,"
	103	"list->prev 0x%p\n",
	104	io, inode->i_ino, io->list.next, io->list.prev);
	105
bd2d0210 TT	106	if (!(io->flag & EXT4_IO_END_UNWRITTEN))
	107	return ret;
	108
	109	ret = ext4_convert_unwritten_extents(inode, offset, size);
	110	if (ret < 0) {
	111	printk(KERN_EMERG "%s: failed to convert unwritten "
	112	"extents to written extents, error is %d "
	113	"io is still on inode %lu aio dio list\n",
	114	__func__, ret, inode->i_ino);
	115	return ret;
	116	}
	117
	118	if (io->iocb)
	119	aio_complete(io->iocb, io->result, 0);
	120	/* clear the DIO AIO unwritten flag */
e9e3bcec ES	121	if (io->flag & EXT4_IO_END_UNWRITTEN) {
	122	io->flag &= ~EXT4_IO_END_UNWRITTEN;
	123	/* Wake up anyone waiting on unwritten extent conversion */
	124	wq = ext4_ioend_wq(io->inode);
	125	if (atomic_dec_and_test(&EXT4_I(inode)->i_aiodio_unwritten) &&
	126	waitqueue_active(wq)) {
	127	wake_up_all(wq);
	128	}
	129	}
	130
bd2d0210 TT	131	return ret;
	132	}
	133
	134	/*
	135	* work on completed aio dio IO, to convert unwritten extents to extents
	136	*/
	137	static void ext4_end_io_work(struct work_struct *work)
	138	{
	139	ext4_io_end_t *io = container_of(work, ext4_io_end_t, work);
	140	struct inode *inode = io->inode;
	141	struct ext4_inode_info *ei = EXT4_I(inode);
	142	unsigned long flags;
	143	int ret;
	144
d73d5046 TM	145	spin_lock_irqsave(&ei->i_completed_io_lock, flags);
	146	if (list_empty(&io->list)) {
	147	spin_unlock_irqrestore(&ei->i_completed_io_lock, flags);
	148	goto free;
	149	}
	150	spin_unlock_irqrestore(&ei->i_completed_io_lock, flags);
	151
8c0bec21 JZ	152	if (!mutex_trylock(&inode->i_mutex)) {
	153	/*
	154	* Requeue the work instead of waiting so that the work
	155	* items queued after this can be processed.
	156	*/
	157	queue_work(EXT4_SB(inode->i_sb)->dio_unwritten_wq, &io->work);
	158	/*
	159	* To prevent the ext4-dio-unwritten thread from keeping
	160	* requeueing end_io requests and occupying cpu for too long,
	161	* yield the cpu if it sees an end_io request that has already
	162	* been requeued.
	163	*/
	164	if (io->flag & EXT4_IO_END_QUEUED)
	165	yield();
	166	io->flag \|= EXT4_IO_END_QUEUED;
	167	return;
	168	}
bd2d0210 TT	169	ret = ext4_end_io_nolock(io);
	170	if (ret < 0) {
	171	mutex_unlock(&inode->i_mutex);
	172	return;
	173	}
	174
	175	spin_lock_irqsave(&ei->i_completed_io_lock, flags);
	176	if (!list_empty(&io->list))
	177	list_del_init(&io->list);
	178	spin_unlock_irqrestore(&ei->i_completed_io_lock, flags);
	179	mutex_unlock(&inode->i_mutex);
d73d5046	180	free:
bd2d0210 TT	181	ext4_free_io_end(io);
	182	}
	183
	184	ext4_io_end_t ext4_init_io_end(struct inode inode, gfp_t flags)
	185	{
b17b35ec	186	ext4_io_end_t *io = kmem_cache_zalloc(io_end_cachep, flags);
bd2d0210	187	if (io) {
f7ad6d2e TT	188	atomic_inc(&EXT4_I(inode)->i_ioend_count);
f7ad6d2e TT	189	io->inode = inode;
bd2d0210 TT	190	INIT_WORK(&io->work, ext4_end_io_work);
	191	INIT_LIST_HEAD(&io->list);
	192	}
	193	return io;
	194	}
	195
	196	/*
	197	* Print an buffer I/O error compatible with the fs/buffer.c. This
	198	* provides compatibility with dmesg scrapers that look for a specific
	199	* buffer I/O error message. We really need a unified error reporting
	200	* structure to userspace ala Digital Unix's uerf system, but it's
	201	* probably not going to happen in my lifetime, due to LKML politics...
	202	*/
	203	static void buffer_io_error(struct buffer_head *bh)
	204	{
	205	char b[BDEVNAME_SIZE];
	206	printk(KERN_ERR "Buffer I/O error on device %s, logical block %llu\n",
	207	bdevname(bh->b_bdev, b),
	208	(unsigned long long)bh->b_blocknr);
	209	}
	210
	211	static void ext4_end_bio(struct bio *bio, int error)
	212	{
	213	ext4_io_end_t *io_end = bio->bi_private;
	214	struct workqueue_struct *wq;
	215	struct inode *inode;
	216	unsigned long flags;
bd2d0210	217	int i;
d50bdd5a	218	sector_t bi_sector = bio->bi_sector;
bd2d0210 TT	219
bd2d0210 TT	220	BUG_ON(!io_end);
bd2d0210 TT	221	bio->bi_private = NULL;
	222	bio->bi_end_io = NULL;
	223	if (test_bit(BIO_UPTODATE, &bio->bi_flags))
	224	error = 0;
bd2d0210 TT	225	bio_put(bio);
bd2d0210 TT	226
bd2d0210 TT	227	for (i = 0; i < io_end->num_io_pages; i++) {
	228	struct page *page = io_end->pages[i]->p_page;
	229	struct buffer_head bh, head;
39db00f1 CW	230	loff_t offset;
39db00f1 CW	231	loff_t io_end_offset;
bd2d0210	232
39db00f1	233	if (error) {
bd2d0210	234	SetPageError(page);
39db00f1 CW	235	set_bit(AS_EIO, &page->mapping->flags);
	236	head = page_buffers(page);
	237	BUG_ON(!head);
	238
	239	io_end_offset = io_end->offset + io_end->size;
bd2d0210 TT	240
	241	offset = (sector_t) page->index << PAGE_CACHE_SHIFT;
	242	bh = head;
	243	do {
	244	if ((offset >= io_end->offset) &&
39db00f1 CW	245	(offset+bh->b_size <= io_end_offset))
	246	buffer_io_error(bh);
	247
bd2d0210 TT	248	offset += bh->b_size;
	249	bh = bh->b_this_page;
	250	} while (bh != head);
	251	}
	252
08da1193	253	put_io_page(io_end->pages[i]);
bd2d0210	254	}
bd2d0210	255	io_end->num_io_pages = 0;
f7ad6d2e TT	256	inode = io_end->inode;
	257
	258	if (error) {
	259	io_end->flag \|= EXT4_IO_END_ERROR;
	260	ext4_warning(inode->i_sb, "I/O error writing to inode %lu "
	261	"(offset %llu size %ld starting block %llu)",
	262	inode->i_ino,
	263	(unsigned long long) io_end->offset,
	264	(long) io_end->size,
	265	(unsigned long long)
d50bdd5a	266	bi_sector >> (inode->i_blkbits - 9));
f7ad6d2e	267	}
bd2d0210	268
b6168443 TT	269	if (!(io_end->flag & EXT4_IO_END_UNWRITTEN)) {
	270	ext4_free_io_end(io_end);
	271	return;
	272	}
	273
bd2d0210 TT	274	/* Add the io_end to per-inode completed io list*/
	275	spin_lock_irqsave(&EXT4_I(inode)->i_completed_io_lock, flags);
	276	list_add_tail(&io_end->list, &EXT4_I(inode)->i_completed_io_list);
	277	spin_unlock_irqrestore(&EXT4_I(inode)->i_completed_io_lock, flags);
	278
	279	wq = EXT4_SB(inode->i_sb)->dio_unwritten_wq;
	280	/* queue the work to convert unwritten extents to written */
	281	queue_work(wq, &io_end->work);
	282	}
	283
	284	void ext4_io_submit(struct ext4_io_submit *io)
	285	{
	286	struct bio *bio = io->io_bio;
	287
	288	if (bio) {
	289	bio_get(io->io_bio);
	290	submit_bio(io->io_op, io->io_bio);
	291	BUG_ON(bio_flagged(io->io_bio, BIO_EOPNOTSUPP));
	292	bio_put(io->io_bio);
	293	}
7dc57615	294	io->io_bio = NULL;
bd2d0210	295	io->io_op = 0;
7dc57615	296	io->io_end = NULL;
bd2d0210 TT	297	}
	298
	299	static int io_submit_init(struct ext4_io_submit *io,
	300	struct inode *inode,
	301	struct writeback_control *wbc,
	302	struct buffer_head *bh)
	303	{
	304	ext4_io_end_t *io_end;
	305	struct page *page = bh->b_page;
	306	int nvecs = bio_get_nr_vecs(bh->b_bdev);
	307	struct bio *bio;
	308
	309	io_end = ext4_init_io_end(inode, GFP_NOFS);
	310	if (!io_end)
	311	return -ENOMEM;
275d3ba6	312	bio = bio_alloc(GFP_NOIO, min(nvecs, BIO_MAX_PAGES));
bd2d0210 TT	313	bio->bi_sector = bh->b_blocknr * (bh->b_size >> 9);
	314	bio->bi_bdev = bh->b_bdev;
	315	bio->bi_private = io->io_end = io_end;
	316	bio->bi_end_io = ext4_end_bio;
	317
bd2d0210 TT	318	io_end->offset = (page->index << PAGE_CACHE_SHIFT) + bh_offset(bh);
	319
	320	io->io_bio = bio;
721a9602	321	io->io_op = (wbc->sync_mode == WB_SYNC_ALL ? WRITE_SYNC : WRITE);
bd2d0210 TT	322	io->io_next_block = bh->b_blocknr;
	323	return 0;
	324	}
	325
	326	static int io_submit_add_bh(struct ext4_io_submit *io,
	327	struct ext4_io_page *io_page,
	328	struct inode *inode,
	329	struct writeback_control *wbc,
	330	struct buffer_head *bh)
	331	{
	332	ext4_io_end_t *io_end;
	333	int ret;
	334
	335	if (buffer_new(bh)) {
	336	clear_buffer_new(bh);
	337	unmap_underlying_metadata(bh->b_bdev, bh->b_blocknr);
	338	}
	339
	340	if (!buffer_mapped(bh) \|\| buffer_delay(bh)) {
	341	if (!buffer_mapped(bh))
	342	clear_buffer_dirty(bh);
	343	if (io->io_bio)
	344	ext4_io_submit(io);
	345	return 0;
	346	}
	347
	348	if (io->io_bio && bh->b_blocknr != io->io_next_block) {
	349	submit_and_retry:
	350	ext4_io_submit(io);
	351	}
	352	if (io->io_bio == NULL) {
	353	ret = io_submit_init(io, inode, wbc, bh);
	354	if (ret)
	355	return ret;
	356	}
	357	io_end = io->io_end;
	358	if ((io_end->num_io_pages >= MAX_IO_PAGES) &&
	359	(io_end->pages[io_end->num_io_pages-1] != io_page))
	360	goto submit_and_retry;
32c80b32 TM	361	if (buffer_uninit(bh) && !(io_end->flag & EXT4_IO_END_UNWRITTEN)) {
	362	io_end->flag \|= EXT4_IO_END_UNWRITTEN;
	363	atomic_inc(&EXT4_I(inode)->i_aiodio_unwritten);
	364	}
bd2d0210 TT	365	io->io_end->size += bh->b_size;
	366	io->io_next_block++;
	367	ret = bio_add_page(io->io_bio, bh->b_page, bh->b_size, bh_offset(bh));
	368	if (ret != bh->b_size)
	369	goto submit_and_retry;
	370	if ((io_end->num_io_pages == 0) \|\|
	371	(io_end->pages[io_end->num_io_pages-1] != io_page)) {
	372	io_end->pages[io_end->num_io_pages++] = io_page;
83668e71	373	atomic_inc(&io_page->p_count);
bd2d0210 TT	374	}
	375	return 0;
	376	}
	377
	378	int ext4_bio_write_page(struct ext4_io_submit *io,
	379	struct page *page,
	380	int len,
	381	struct writeback_control *wbc)
	382	{
	383	struct inode *inode = page->mapping->host;
	384	unsigned block_start, block_end, blocksize;
	385	struct ext4_io_page *io_page;
	386	struct buffer_head bh, head;
	387	int ret = 0;
	388
	389	blocksize = 1 << inode->i_blkbits;
	390
d50bdd5a	391	BUG_ON(!PageLocked(page));
bd2d0210	392	BUG_ON(PageWriteback(page));
bd2d0210 TT	393
	394	io_page = kmem_cache_alloc(io_page_cachep, GFP_NOFS);
	395	if (!io_page) {
	396	set_page_dirty(page);
	397	unlock_page(page);
	398	return -ENOMEM;
	399	}
	400	io_page->p_page = page;
83668e71	401	atomic_set(&io_page->p_count, 1);
bd2d0210	402	get_page(page);
a54aa761 TT	403	set_page_writeback(page);
a54aa761 TT	404	ClearPageError(page);
bd2d0210 TT	405
	406	for (bh = head = page_buffers(page), block_start = 0;
	407	bh != head \|\| !block_start;
	408	block_start = block_end, bh = bh->b_this_page) {
d50bdd5a	409
bd2d0210 TT	410	block_end = block_start + blocksize;
	411	if (block_start >= len) {
	412	clear_buffer_dirty(bh);
	413	set_buffer_uptodate(bh);
	414	continue;
	415	}
d50bdd5a	416	clear_buffer_dirty(bh);
bd2d0210 TT	417	ret = io_submit_add_bh(io, io_page, inode, wbc, bh);
	418	if (ret) {
	419	/*
	420	* We only get here on ENOMEM. Not much else
	421	* we can do but mark the page as dirty, and
	422	* better luck next time.
	423	*/
	424	set_page_dirty(page);
	425	break;
	426	}
	427	}
	428	unlock_page(page);
	429	/*
	430	* If the page was truncated before we could do the writeback,
	431	* or we had a memory allocation error while trying to write
	432	* the first buffer head, we won't have submitted any pages for
	433	* I/O. In that case we need to make sure we've cleared the
	434	* PageWriteback bit from the page to prevent the system from
	435	* wedging later on.
	436	*/
83668e71	437	put_io_page(io_page);
bd2d0210 TT	438	return ret;
bd2d0210 TT	439	}