[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/aio.h>
#include <linux/uio.h>
#include <linux/bio.h>
#include <linux/workqueue.h>
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/mm.h>

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

static struct kmem_cache *io_end_cachep;

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

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

/*
 * This function is called by ext4_evict_inode() to make sure there is
 * no more pending I/O completion work left to do.
 */
void ext4_ioend_shutdown(struct inode *inode)
{
	wait_queue_head_t *wq = ext4_ioend_wq(inode);

	wait_event(*wq, (atomic_read(&EXT4_I(inode)->i_ioend_count) == 0));
	/*
	 * We need to make sure the work structure is finished being
	 * used before we let the inode get destroyed.
	 */
	if (work_pending(&EXT4_I(inode)->i_unwritten_work))
		cancel_work_sync(&EXT4_I(inode)->i_unwritten_work);
}

void ext4_free_io_end(ext4_io_end_t *io)
{
	BUG_ON(!io);
	BUG_ON(!list_empty(&io->list));
	BUG_ON(io->flag & EXT4_IO_END_UNWRITTEN);

	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. */
static int ext4_end_io(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);
	}
	/* Wake up anyone waiting on unwritten extent conversion */
	if (atomic_dec_and_test(&EXT4_I(inode)->i_unwritten))
		wake_up_all(ext4_ioend_wq(inode));
	if (io->flag & EXT4_IO_END_DIRECT)
		inode_dio_done(inode);
	if (io->iocb)
		aio_complete(io->iocb, io->result, 0);
	return ret;
}

static void dump_completed_IO(struct inode *inode)
{
#ifdef	EXT4FS_DEBUG
	struct list_head *cur, *before, *after;
	ext4_io_end_t *io, *io0, *io1;

	if (list_empty(&EXT4_I(inode)->i_completed_io_list)) {
		ext4_debug("inode %lu completed_io list is empty\n",
			   inode->i_ino);
		return;
	}

	ext4_debug("Dump inode %lu completed_io list\n", inode->i_ino);
	list_for_each_entry(io, &EXT4_I(inode)->i_completed_io_list, list) {
		cur = &io->list;
		before = cur->prev;
		io0 = container_of(before, ext4_io_end_t, list);
		after = cur->next;
		io1 = container_of(after, ext4_io_end_t, list);

		ext4_debug("io 0x%p from inode %lu,prev 0x%p,next 0x%p\n",
			    io, inode->i_ino, io0, io1);
	}
#endif
}

/* Add the io_end to per-inode completed end_io list. */
void ext4_add_complete_io(ext4_io_end_t *io_end)
{
	struct ext4_inode_info *ei = EXT4_I(io_end->inode);
	struct workqueue_struct *wq;
	unsigned long flags;

	BUG_ON(!(io_end->flag & EXT4_IO_END_UNWRITTEN));
	wq = EXT4_SB(io_end->inode->i_sb)->dio_unwritten_wq;

	spin_lock_irqsave(&ei->i_completed_io_lock, flags);
	if (list_empty(&ei->i_completed_io_list))
		queue_work(wq, &ei->i_unwritten_work);
	list_add_tail(&io_end->list, &ei->i_completed_io_list);
	spin_unlock_irqrestore(&ei->i_completed_io_lock, flags);
}

static int ext4_do_flush_completed_IO(struct inode *inode)
{
	ext4_io_end_t *io;
	struct list_head unwritten;
	unsigned long flags;
	struct ext4_inode_info *ei = EXT4_I(inode);
	int err, ret = 0;

	spin_lock_irqsave(&ei->i_completed_io_lock, flags);
	dump_completed_IO(inode);
	list_replace_init(&ei->i_completed_io_list, &unwritten);
	spin_unlock_irqrestore(&ei->i_completed_io_lock, flags);

	while (!list_empty(&unwritten)) {
		io = list_entry(unwritten.next, ext4_io_end_t, list);
		BUG_ON(!(io->flag & EXT4_IO_END_UNWRITTEN));
		list_del_init(&io->list);

		err = ext4_end_io(io);
		if (unlikely(!ret && err))
			ret = err;
		io->flag &= ~EXT4_IO_END_UNWRITTEN;
		ext4_free_io_end(io);
	}
	return ret;
}

/*
 * work on completed aio dio IO, to convert unwritten extents to extents
 */
void ext4_end_io_work(struct work_struct *work)
{
	struct ext4_inode_info *ei = container_of(work, struct ext4_inode_info,
						  i_unwritten_work);
	ext4_do_flush_completed_IO(&ei->vfs_inode);
}

int ext4_flush_unwritten_io(struct inode *inode)
{
	int ret;
	WARN_ON_ONCE(!mutex_is_locked(&inode->i_mutex) &&
		     !(inode->i_state & I_FREEING));
	ret = ext4_do_flush_completed_IO(inode);
	ext4_unwritten_wait(inode);
	return ret;
}

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_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 inode *inode;
	int i;
	int blocksize;
	sector_t bi_sector = bio->bi_sector;

	BUG_ON(!io_end);
	inode = io_end->inode;
	blocksize = 1 << inode->i_blkbits;
	bio->bi_private = NULL;
	bio->bi_end_io = NULL;
	if (test_bit(BIO_UPTODATE, &bio->bi_flags))
		error = 0;
	for (i = 0; i < bio->bi_vcnt; i++) {
		struct bio_vec *bvec = &bio->bi_io_vec[i];
		struct page *page = bvec->bv_page;
		struct buffer_head *bh, *head;
		unsigned bio_start = bvec->bv_offset;
		unsigned bio_end = bio_start + bvec->bv_len;
		unsigned under_io = 0;
		unsigned long flags;

		if (!page)
			continue;

		if (error) {
			SetPageError(page);
			set_bit(AS_EIO, &page->mapping->flags);
		}
		bh = head = page_buffers(page);
		/*
		 * We check all buffers in the page under BH_Uptodate_Lock
		 * to avoid races with other end io clearing async_write flags
		 */
		local_irq_save(flags);
		bit_spin_lock(BH_Uptodate_Lock, &head->b_state);
		do {
			if (bh_offset(bh) < bio_start ||
			    bh_offset(bh) + blocksize > bio_end) {
				if (buffer_async_write(bh))
					under_io++;
				continue;
			}
			clear_buffer_async_write(bh);
			if (error)
				buffer_io_error(bh);
		} while ((bh = bh->b_this_page) != head);
		bit_spin_unlock(BH_Uptodate_Lock, &head->b_state);
		local_irq_restore(flags);
		if (!under_io)
			end_page_writeback(page);
	}
	bio_put(bio);

	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;
	}

	ext4_add_complete_io(io_end);
}

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 inode *inode,
			    struct writeback_control *wbc,
			    struct buffer_head *bh)
{
	ext4_io_end_t *io_end;
	int ret;

	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 (test_clear_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;
	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, blocksize;
	struct buffer_head *bh, *head;
	int ret = 0;
	int nr_submitted = 0;

	blocksize = 1 << inode->i_blkbits;

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

	set_page_writeback(page);
	ClearPageError(page);

	/*
	 * In the first loop we prepare and mark buffers to submit. We have to
	 * mark all buffers in the page before submitting so that
	 * end_page_writeback() cannot be called from ext4_bio_end_io() when IO
	 * on the first buffer finishes and we are still working on submitting
	 * the second buffer.
	 */
	bh = head = page_buffers(page);
	do {
		block_start = bh_offset(bh);
		if (block_start >= len) {
			/*
			 * Comments copied from block_write_full_page_endio:
			 *
			 * The page straddles i_size.  It must be zeroed out on
			 * each and every writepage invocation because it may
			 * be mmapped.  "A file is mapped in multiples of the
			 * page size.  For a file that is not a multiple of
			 * the  page size, the remaining memory is zeroed when
			 * mapped, and writes to that region are not written
			 * out to the file."
			 */
			zero_user_segment(page, block_start,
					  block_start + blocksize);
			clear_buffer_dirty(bh);
			set_buffer_uptodate(bh);
			continue;
		}
		if (!buffer_dirty(bh) || buffer_delay(bh) ||
		    !buffer_mapped(bh) || buffer_unwritten(bh)) {
			/* A hole? We can safely clear the dirty bit */
			if (!buffer_mapped(bh))
				clear_buffer_dirty(bh);
			if (io->io_bio)
				ext4_io_submit(io);
			continue;
		}
		if (buffer_new(bh)) {
			clear_buffer_new(bh);
			unmap_underlying_metadata(bh->b_bdev, bh->b_blocknr);
		}
		set_buffer_async_write(bh);
	} while ((bh = bh->b_this_page) != head);

	/* Now submit buffers to write */
	bh = head = page_buffers(page);
	do {
		if (!buffer_async_write(bh))
			continue;
		ret = io_submit_add_bh(io, 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.
			 */
			redirty_page_for_writepage(wbc, page);
			break;
		}
		nr_submitted++;
		clear_buffer_dirty(bh);
	} while ((bh = bh->b_this_page) != head);

	/* Error stopped previous loop? Clean up buffers... */
	if (ret) {
		do {
			clear_buffer_async_write(bh);
			bh = bh->b_this_page;
		} while (bh != head);
	}
	unlock_page(page);
	/* Nothing submitted - we have to end page writeback */
	if (!nr_submitted)
		end_page_writeback(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>
a27bb332	21	#include <linux/aio.h>
bd2d0210 TT	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>
1ae48a63	27	#include <linux/mm.h>
bd2d0210 TT	28
	29	#include "ext4_jbd2.h"
	30	#include "xattr.h"
	31	#include "acl.h"
bd2d0210	32
0058f965	33	static struct kmem_cache *io_end_cachep;
bd2d0210	34
5dabfc78	35	int __init ext4_init_pageio(void)
bd2d0210	36	{
bd2d0210	37	io_end_cachep = KMEM_CACHE(ext4_io_end, SLAB_RECLAIM_ACCOUNT);
0058f965	38	if (io_end_cachep == NULL)
bd2d0210	39	return -ENOMEM;
bd2d0210 TT	40	return 0;
	41	}
	42
5dabfc78	43	void ext4_exit_pageio(void)
bd2d0210 TT	44	{
bd2d0210 TT	45	kmem_cache_destroy(io_end_cachep);
bd2d0210 TT	46	}
bd2d0210 TT	47
1ada47d9 TT	48	/*
	49	* This function is called by ext4_evict_inode() to make sure there is
	50	* no more pending I/O completion work left to do.
	51	*/
	52	void ext4_ioend_shutdown(struct inode *inode)
f7ad6d2e	53	{
e9e3bcec	54	wait_queue_head_t *wq = ext4_ioend_wq(inode);
f7ad6d2e TT	55
f7ad6d2e TT	56	wait_event(*wq, (atomic_read(&EXT4_I(inode)->i_ioend_count) == 0));
1ada47d9 TT	57	/*
	58	* We need to make sure the work structure is finished being
	59	* used before we let the inode get destroyed.
	60	*/
	61	if (work_pending(&EXT4_I(inode)->i_unwritten_work))
	62	cancel_work_sync(&EXT4_I(inode)->i_unwritten_work);
f7ad6d2e TT	63	}
f7ad6d2e TT	64
a549984b	65	void ext4_free_io_end(ext4_io_end_t *io)
bd2d0210	66	{
a549984b TT	67	BUG_ON(!io);
	68	BUG_ON(!list_empty(&io->list));
	69	BUG_ON(io->flag & EXT4_IO_END_UNWRITTEN);
82e54229	70
a549984b TT	71	if (atomic_dec_and_test(&EXT4_I(io->inode)->i_ioend_count))
	72	wake_up_all(ext4_ioend_wq(io->inode));
	73	kmem_cache_free(io_end_cachep, io);
bd2d0210 TT	74	}
bd2d0210 TT	75
28a535f9 DM	76	/* check a range of space and convert unwritten extents to written. */
28a535f9 DM	77	static int ext4_end_io(ext4_io_end_t *io)
bd2d0210 TT	78	{
	79	struct inode *inode = io->inode;
	80	loff_t offset = io->offset;
	81	ssize_t size = io->size;
	82	int ret = 0;
	83
	84	ext4_debug("ext4_end_io_nolock: io 0x%p from inode %lu,list->next 0x%p,"
	85	"list->prev 0x%p\n",
	86	io, inode->i_ino, io->list.next, io->list.prev);
	87
bd2d0210 TT	88	ret = ext4_convert_unwritten_extents(inode, offset, size);
bd2d0210 TT	89	if (ret < 0) {
b82e384c TT	90	ext4_msg(inode->i_sb, KERN_EMERG,
	91	"failed to convert unwritten extents to written "
	92	"extents -- potential data loss! "
	93	"(inode %lu, offset %llu, size %zd, error %d)",
	94	inode->i_ino, offset, size, ret);
bd2d0210	95	}
a549984b TT	96	/* Wake up anyone waiting on unwritten extent conversion */
	97	if (atomic_dec_and_test(&EXT4_I(inode)->i_unwritten))
	98	wake_up_all(ext4_ioend_wq(inode));
	99	if (io->flag & EXT4_IO_END_DIRECT)
	100	inode_dio_done(inode);
	101	if (io->iocb)
	102	aio_complete(io->iocb, io->result, 0);
bd2d0210 TT	103	return ret;
	104	}
	105
28a535f9 DM	106	static void dump_completed_IO(struct inode *inode)
	107	{
	108	#ifdef EXT4FS_DEBUG
	109	struct list_head cur, before, *after;
	110	ext4_io_end_t io, io0, *io1;
28a535f9 DM	111
	112	if (list_empty(&EXT4_I(inode)->i_completed_io_list)) {
	113	ext4_debug("inode %lu completed_io list is empty\n",
	114	inode->i_ino);
	115	return;
	116	}
	117
	118	ext4_debug("Dump inode %lu completed_io list\n", inode->i_ino);
	119	list_for_each_entry(io, &EXT4_I(inode)->i_completed_io_list, list) {
	120	cur = &io->list;
	121	before = cur->prev;
	122	io0 = container_of(before, ext4_io_end_t, list);
	123	after = cur->next;
	124	io1 = container_of(after, ext4_io_end_t, list);
	125
	126	ext4_debug("io 0x%p from inode %lu,prev 0x%p,next 0x%p\n",
	127	io, inode->i_ino, io0, io1);
	128	}
	129	#endif
	130	}
	131
	132	/* Add the io_end to per-inode completed end_io list. */
a549984b	133	void ext4_add_complete_io(ext4_io_end_t *io_end)
bd2d0210	134	{
28a535f9 DM	135	struct ext4_inode_info *ei = EXT4_I(io_end->inode);
	136	struct workqueue_struct *wq;
	137	unsigned long flags;
	138
	139	BUG_ON(!(io_end->flag & EXT4_IO_END_UNWRITTEN));
	140	wq = EXT4_SB(io_end->inode->i_sb)->dio_unwritten_wq;
bd2d0210	141
d73d5046	142	spin_lock_irqsave(&ei->i_completed_io_lock, flags);
84c17543 JK	143	if (list_empty(&ei->i_completed_io_list))
84c17543 JK	144	queue_work(wq, &ei->i_unwritten_work);
28a535f9 DM	145	list_add_tail(&io_end->list, &ei->i_completed_io_list);
	146	spin_unlock_irqrestore(&ei->i_completed_io_lock, flags);
	147	}
d73d5046	148
84c17543	149	static int ext4_do_flush_completed_IO(struct inode *inode)
28a535f9 DM	150	{
28a535f9 DM	151	ext4_io_end_t *io;
002bd7fa	152	struct list_head unwritten;
28a535f9 DM	153	unsigned long flags;
	154	struct ext4_inode_info *ei = EXT4_I(inode);
	155	int err, ret = 0;
	156
28a535f9 DM	157	spin_lock_irqsave(&ei->i_completed_io_lock, flags);
	158	dump_completed_IO(inode);
	159	list_replace_init(&ei->i_completed_io_list, &unwritten);
	160	spin_unlock_irqrestore(&ei->i_completed_io_lock, flags);
	161
	162	while (!list_empty(&unwritten)) {
	163	io = list_entry(unwritten.next, ext4_io_end_t, list);
	164	BUG_ON(!(io->flag & EXT4_IO_END_UNWRITTEN));
	165	list_del_init(&io->list);
	166
	167	err = ext4_end_io(io);
	168	if (unlikely(!ret && err))
	169	ret = err;
a549984b TT	170	io->flag &= ~EXT4_IO_END_UNWRITTEN;
a549984b TT	171	ext4_free_io_end(io);
28a535f9 DM	172	}
	173	return ret;
	174	}
	175
	176	/*
	177	* work on completed aio dio IO, to convert unwritten extents to extents
	178	*/
84c17543	179	void ext4_end_io_work(struct work_struct *work)
28a535f9	180	{
84c17543 JK	181	struct ext4_inode_info *ei = container_of(work, struct ext4_inode_info,
	182	i_unwritten_work);
	183	ext4_do_flush_completed_IO(&ei->vfs_inode);
28a535f9 DM	184	}
28a535f9 DM	185
c278531d	186	int ext4_flush_unwritten_io(struct inode *inode)
28a535f9	187	{
c278531d DM	188	int ret;
	189	WARN_ON_ONCE(!mutex_is_locked(&inode->i_mutex) &&
	190	!(inode->i_state & I_FREEING));
84c17543	191	ret = ext4_do_flush_completed_IO(inode);
c278531d DM	192	ext4_unwritten_wait(inode);
c278531d DM	193	return ret;
bd2d0210 TT	194	}
	195
	196	ext4_io_end_t ext4_init_io_end(struct inode inode, gfp_t flags)
	197	{
b17b35ec	198	ext4_io_end_t *io = kmem_cache_zalloc(io_end_cachep, flags);
bd2d0210	199	if (io) {
f7ad6d2e TT	200	atomic_inc(&EXT4_I(inode)->i_ioend_count);
f7ad6d2e TT	201	io->inode = inode;
bd2d0210 TT	202	INIT_LIST_HEAD(&io->list);
	203	}
	204	return io;
	205	}
	206
	207	/*
	208	* Print an buffer I/O error compatible with the fs/buffer.c. This
	209	* provides compatibility with dmesg scrapers that look for a specific
	210	* buffer I/O error message. We really need a unified error reporting
	211	* structure to userspace ala Digital Unix's uerf system, but it's
	212	* probably not going to happen in my lifetime, due to LKML politics...
	213	*/
	214	static void buffer_io_error(struct buffer_head *bh)
	215	{
	216	char b[BDEVNAME_SIZE];
	217	printk(KERN_ERR "Buffer I/O error on device %s, logical block %llu\n",
	218	bdevname(bh->b_bdev, b),
	219	(unsigned long long)bh->b_blocknr);
	220	}
	221
	222	static void ext4_end_bio(struct bio *bio, int error)
	223	{
	224	ext4_io_end_t *io_end = bio->bi_private;
bd2d0210	225	struct inode *inode;
bd2d0210	226	int i;
0058f965	227	int blocksize;
d50bdd5a	228	sector_t bi_sector = bio->bi_sector;
bd2d0210 TT	229
bd2d0210 TT	230	BUG_ON(!io_end);
0058f965 JK	231	inode = io_end->inode;
0058f965 JK	232	blocksize = 1 << inode->i_blkbits;
bd2d0210 TT	233	bio->bi_private = NULL;
	234	bio->bi_end_io = NULL;
	235	if (test_bit(BIO_UPTODATE, &bio->bi_flags))
	236	error = 0;
0058f965 JK	237	for (i = 0; i < bio->bi_vcnt; i++) {
	238	struct bio_vec *bvec = &bio->bi_io_vec[i];
	239	struct page *page = bvec->bv_page;
bd2d0210	240	struct buffer_head bh, head;
0058f965 JK	241	unsigned bio_start = bvec->bv_offset;
	242	unsigned bio_end = bio_start + bvec->bv_len;
	243	unsigned under_io = 0;
	244	unsigned long flags;
	245
	246	if (!page)
	247	continue;
bd2d0210	248
39db00f1	249	if (error) {
bd2d0210	250	SetPageError(page);
39db00f1	251	set_bit(AS_EIO, &page->mapping->flags);
bd2d0210	252	}
0058f965 JK	253	bh = head = page_buffers(page);
	254	/*
	255	* We check all buffers in the page under BH_Uptodate_Lock
	256	* to avoid races with other end io clearing async_write flags
	257	*/
	258	local_irq_save(flags);
	259	bit_spin_lock(BH_Uptodate_Lock, &head->b_state);
	260	do {
	261	if (bh_offset(bh) < bio_start \|\|
	262	bh_offset(bh) + blocksize > bio_end) {
	263	if (buffer_async_write(bh))
	264	under_io++;
	265	continue;
	266	}
	267	clear_buffer_async_write(bh);
	268	if (error)
	269	buffer_io_error(bh);
	270	} while ((bh = bh->b_this_page) != head);
	271	bit_spin_unlock(BH_Uptodate_Lock, &head->b_state);
	272	local_irq_restore(flags);
	273	if (!under_io)
	274	end_page_writeback(page);
bd2d0210	275	}
0058f965	276	bio_put(bio);
f7ad6d2e TT	277
	278	if (error) {
	279	io_end->flag \|= EXT4_IO_END_ERROR;
	280	ext4_warning(inode->i_sb, "I/O error writing to inode %lu "
	281	"(offset %llu size %ld starting block %llu)",
	282	inode->i_ino,
	283	(unsigned long long) io_end->offset,
	284	(long) io_end->size,
	285	(unsigned long long)
d50bdd5a	286	bi_sector >> (inode->i_blkbits - 9));
f7ad6d2e	287	}
bd2d0210	288
a549984b TT	289	if (!(io_end->flag & EXT4_IO_END_UNWRITTEN)) {
	290	ext4_free_io_end(io_end);
	291	return;
	292	}
	293
	294	ext4_add_complete_io(io_end);
bd2d0210 TT	295	}
	296
	297	void ext4_io_submit(struct ext4_io_submit *io)
	298	{
	299	struct bio *bio = io->io_bio;
	300
	301	if (bio) {
	302	bio_get(io->io_bio);
	303	submit_bio(io->io_op, io->io_bio);
	304	BUG_ON(bio_flagged(io->io_bio, BIO_EOPNOTSUPP));
	305	bio_put(io->io_bio);
	306	}
7dc57615	307	io->io_bio = NULL;
a549984b	308	io->io_op = 0;
7dc57615	309	io->io_end = NULL;
bd2d0210 TT	310	}
bd2d0210 TT	311
a549984b TT	312	static int io_submit_init(struct ext4_io_submit *io,
	313	struct inode *inode,
	314	struct writeback_control *wbc,
	315	struct buffer_head *bh)
bd2d0210	316	{
a549984b TT	317	ext4_io_end_t *io_end;
a549984b TT	318	struct page *page = bh->b_page;
bd2d0210 TT	319	int nvecs = bio_get_nr_vecs(bh->b_bdev);
	320	struct bio *bio;
	321
a549984b TT	322	io_end = ext4_init_io_end(inode, GFP_NOFS);
	323	if (!io_end)
	324	return -ENOMEM;
275d3ba6	325	bio = bio_alloc(GFP_NOIO, min(nvecs, BIO_MAX_PAGES));
bd2d0210 TT	326	bio->bi_sector = bh->b_blocknr * (bh->b_size >> 9);
bd2d0210 TT	327	bio->bi_bdev = bh->b_bdev;
a549984b	328	bio->bi_private = io->io_end = io_end;
bd2d0210	329	bio->bi_end_io = ext4_end_bio;
a549984b TT	330
	331	io_end->offset = (page->index << PAGE_CACHE_SHIFT) + bh_offset(bh);
	332
bd2d0210	333	io->io_bio = bio;
a549984b	334	io->io_op = (wbc->sync_mode == WB_SYNC_ALL ? WRITE_SYNC : WRITE);
bd2d0210 TT	335	io->io_next_block = bh->b_blocknr;
	336	return 0;
	337	}
	338
	339	static int io_submit_add_bh(struct ext4_io_submit *io,
bd2d0210	340	struct inode *inode,
a549984b	341	struct writeback_control *wbc,
bd2d0210 TT	342	struct buffer_head *bh)
	343	{
	344	ext4_io_end_t *io_end;
	345	int ret;
	346
bd2d0210 TT	347	if (io->io_bio && bh->b_blocknr != io->io_next_block) {
	348	submit_and_retry:
	349	ext4_io_submit(io);
	350	}
	351	if (io->io_bio == NULL) {
a549984b	352	ret = io_submit_init(io, inode, wbc, bh);
bd2d0210 TT	353	if (ret)
	354	return ret;
	355	}
	356	io_end = io->io_end;
7b001d6a	357	if (test_clear_buffer_uninit(bh))
0edeb71d	358	ext4_set_io_unwritten_flag(inode, io_end);
a549984b	359	io->io_end->size += bh->b_size;
bd2d0210	360	io->io_next_block++;
a549984b TT	361	ret = bio_add_page(io->io_bio, bh->b_page, bh->b_size, bh_offset(bh));
	362	if (ret != bh->b_size)
	363	goto submit_and_retry;
bd2d0210 TT	364	return 0;
	365	}
	366
	367	int ext4_bio_write_page(struct ext4_io_submit *io,
	368	struct page *page,
	369	int len,
	370	struct writeback_control *wbc)
	371	{
	372	struct inode *inode = page->mapping->host;
0058f965	373	unsigned block_start, blocksize;
bd2d0210 TT	374	struct buffer_head bh, head;
bd2d0210 TT	375	int ret = 0;
0058f965	376	int nr_submitted = 0;
bd2d0210 TT	377
	378	blocksize = 1 << inode->i_blkbits;
	379
d50bdd5a	380	BUG_ON(!PageLocked(page));
bd2d0210	381	BUG_ON(PageWriteback(page));
bd2d0210	382
a54aa761 TT	383	set_page_writeback(page);
a54aa761 TT	384	ClearPageError(page);
bd2d0210	385
0058f965 JK	386	/*
	387	* In the first loop we prepare and mark buffers to submit. We have to
	388	* mark all buffers in the page before submitting so that
	389	* end_page_writeback() cannot be called from ext4_bio_end_io() when IO
	390	* on the first buffer finishes and we are still working on submitting
	391	* the second buffer.
	392	*/
	393	bh = head = page_buffers(page);
	394	do {
	395	block_start = bh_offset(bh);
bd2d0210	396	if (block_start >= len) {
5a0dc736 YY	397	/*
	398	* Comments copied from block_write_full_page_endio:
	399	*
	400	* The page straddles i_size. It must be zeroed out on
	401	* each and every writepage invocation because it may
	402	* be mmapped. "A file is mapped in multiples of the
	403	* page size. For a file that is not a multiple of
	404	* the page size, the remaining memory is zeroed when
	405	* mapped, and writes to that region are not written
	406	* out to the file."
	407	*/
0058f965 JK	408	zero_user_segment(page, block_start,
0058f965 JK	409	block_start + blocksize);
bd2d0210 TT	410	clear_buffer_dirty(bh);
	411	set_buffer_uptodate(bh);
	412	continue;
	413	}
8a850c3f JK	414	if (!buffer_dirty(bh) \|\| buffer_delay(bh) \|\|
	415	!buffer_mapped(bh) \|\| buffer_unwritten(bh)) {
	416	/* A hole? We can safely clear the dirty bit */
	417	if (!buffer_mapped(bh))
	418	clear_buffer_dirty(bh);
	419	if (io->io_bio)
	420	ext4_io_submit(io);
	421	continue;
	422	}
0058f965 JK	423	if (buffer_new(bh)) {
	424	clear_buffer_new(bh);
	425	unmap_underlying_metadata(bh->b_bdev, bh->b_blocknr);
	426	}
	427	set_buffer_async_write(bh);
	428	} while ((bh = bh->b_this_page) != head);
	429
	430	/* Now submit buffers to write */
	431	bh = head = page_buffers(page);
	432	do {
	433	if (!buffer_async_write(bh))
	434	continue;
a549984b	435	ret = io_submit_add_bh(io, inode, wbc, bh);
bd2d0210 TT	436	if (ret) {
	437	/*
	438	* We only get here on ENOMEM. Not much else
	439	* we can do but mark the page as dirty, and
	440	* better luck next time.
	441	*/
1ae48a63	442	redirty_page_for_writepage(wbc, page);
bd2d0210 TT	443	break;
bd2d0210 TT	444	}
0058f965	445	nr_submitted++;
1ae48a63	446	clear_buffer_dirty(bh);
0058f965 JK	447	} while ((bh = bh->b_this_page) != head);
	448
	449	/* Error stopped previous loop? Clean up buffers... */
	450	if (ret) {
	451	do {
	452	clear_buffer_async_write(bh);
	453	bh = bh->b_this_page;
	454	} while (bh != head);
bd2d0210 TT	455	}
bd2d0210 TT	456	unlock_page(page);
0058f965 JK	457	/* Nothing submitted - we have to end page writeback */
	458	if (!nr_submitted)
	459	end_page_writeback(page);
bd2d0210 TT	460	return ret;
bd2d0210 TT	461	}