[thirdparty/kernel/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/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 <linux/ratelimit.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);
}

/*
 * 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_ratelimited(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_finish_bio(struct bio *bio)
{
	int i;
	int error = !test_bit(BIO_UPTODATE, &bio->bi_flags);

	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) + bh->b_size > 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);
	}
}

static void ext4_release_io_end(ext4_io_end_t *io_end)
{
	struct bio *bio, *next_bio;

	BUG_ON(!list_empty(&io_end->list));
	BUG_ON(io_end->flag & EXT4_IO_END_UNWRITTEN);
	WARN_ON(io_end->handle);

	if (atomic_dec_and_test(&EXT4_I(io_end->inode)->i_ioend_count))
		wake_up_all(ext4_ioend_wq(io_end->inode));

	for (bio = io_end->bio; bio; bio = next_bio) {
		next_bio = bio->bi_private;
		ext4_finish_bio(bio);
		bio_put(bio);
	}
	kmem_cache_free(io_end_cachep, io_end);
}

static void ext4_clear_io_unwritten_flag(ext4_io_end_t *io_end)
{
	struct inode *inode = io_end->inode;

	io_end->flag &= ~EXT4_IO_END_UNWRITTEN;
	/* 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));
}

/*
 * Check a range of space and convert unwritten extents to written. Note that
 * we are protected from truncate touching same part of extent tree by the
 * fact that truncate code waits for all DIO to finish (thus exclusion from
 * direct IO is achieved) and also waits for PageWriteback bits. Thus we
 * cannot get to ext4_ext_truncate() before all IOs overlapping that range are
 * completed (happens from ext4_free_ioend()).
 */
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;
	handle_t *handle = io->handle;
	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);

	io->handle = NULL;	/* Following call will use up the handle */
	ret = ext4_convert_unwritten_extents(handle, 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);
	}
	ext4_clear_io_unwritten_flag(io);
	ext4_release_io_end(io);
	return ret;
}

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

	if (list_empty(head))
		return;

	ext4_debug("Dump inode %lu completed io list\n", inode->i_ino);
	list_for_each_entry(io, head, 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. */
static 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;

	/* Only reserved conversions from writeback should enter here */
	WARN_ON(!(io_end->flag & EXT4_IO_END_UNWRITTEN));
	WARN_ON(!io_end->handle);
	spin_lock_irqsave(&ei->i_completed_io_lock, flags);
	wq = EXT4_SB(io_end->inode->i_sb)->rsv_conversion_wq;
	if (list_empty(&ei->i_rsv_conversion_list))
		queue_work(wq, &ei->i_rsv_conversion_work);
	list_add_tail(&io_end->list, &ei->i_rsv_conversion_list);
	spin_unlock_irqrestore(&ei->i_completed_io_lock, flags);
}

static int ext4_do_flush_completed_IO(struct inode *inode,
				      struct list_head *head)
{
	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, head);
	list_replace_init(head, &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;
	}
	return ret;
}

/*
 * work on completed IO, to convert unwritten extents to extents
 */
void ext4_end_io_rsv_work(struct work_struct *work)
{
	struct ext4_inode_info *ei = container_of(work, struct ext4_inode_info,
						  i_rsv_conversion_work);
	ext4_do_flush_completed_IO(&ei->vfs_inode, &ei->i_rsv_conversion_list);
}

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);
		atomic_set(&io->count, 1);
	}
	return io;
}

void ext4_put_io_end_defer(ext4_io_end_t *io_end)
{
	if (atomic_dec_and_test(&io_end->count)) {
		if (!(io_end->flag & EXT4_IO_END_UNWRITTEN) || !io_end->size) {
			ext4_release_io_end(io_end);
			return;
		}
		ext4_add_complete_io(io_end);
	}
}

int ext4_put_io_end(ext4_io_end_t *io_end)
{
	int err = 0;

	if (atomic_dec_and_test(&io_end->count)) {
		if (io_end->flag & EXT4_IO_END_UNWRITTEN) {
			err = ext4_convert_unwritten_extents(io_end->handle,
						io_end->inode, io_end->offset,
						io_end->size);
			io_end->handle = NULL;
			ext4_clear_io_unwritten_flag(io_end);
		}
		ext4_release_io_end(io_end);
	}
	return err;
}

ext4_io_end_t *ext4_get_io_end(ext4_io_end_t *io_end)
{
	atomic_inc(&io_end->count);
	return io_end;
}

/* BIO completion function for page writeback */
static void ext4_end_bio(struct bio *bio, int error)
{
	ext4_io_end_t *io_end = bio->bi_private;
	sector_t bi_sector = bio->bi_sector;

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

	if (error) {
		struct inode *inode = io_end->inode;

		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) {
		/*
		 * Link bio into list hanging from io_end. We have to do it
		 * atomically as bio completions can be racing against each
		 * other.
		 */
		bio->bi_private = xchg(&io_end->bio, bio);
		ext4_put_io_end_defer(io_end);
	} else {
		/*
		 * Drop io_end reference early. Inode can get freed once
		 * we finish the bio.
		 */
		ext4_put_io_end_defer(io_end);
		ext4_finish_bio(bio);
		bio_put(bio);
	}
}

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;
}

void ext4_io_submit_init(struct ext4_io_submit *io,
			 struct writeback_control *wbc)
{
	io->io_op = (wbc->sync_mode == WB_SYNC_ALL ?  WRITE_SYNC : WRITE);
	io->io_bio = NULL;
	io->io_end = NULL;
}

static int io_submit_init_bio(struct ext4_io_submit *io,
			      struct buffer_head *bh)
{
	int nvecs = bio_get_nr_vecs(bh->b_bdev);
	struct bio *bio;

	bio = bio_alloc(GFP_NOIO, min(nvecs, BIO_MAX_PAGES));
	if (!bio)
		return -ENOMEM;
	bio->bi_sector = bh->b_blocknr * (bh->b_size >> 9);
	bio->bi_bdev = bh->b_bdev;
	bio->bi_end_io = ext4_end_bio;
	bio->bi_private = ext4_get_io_end(io->io_end);
	io->io_bio = bio;
	io->io_next_block = bh->b_blocknr;
	return 0;
}

static int io_submit_add_bh(struct ext4_io_submit *io,
			    struct inode *inode,
			    struct buffer_head *bh)
{
	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_bio(io, bh);
		if (ret)
			return ret;
	}
	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;
	io->io_next_block++;
	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, 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>
e8974c39	28	#include <linux/ratelimit.h>
bd2d0210 TT	29
	30	#include "ext4_jbd2.h"
	31	#include "xattr.h"
	32	#include "acl.h"
bd2d0210	33
0058f965	34	static struct kmem_cache *io_end_cachep;
bd2d0210	35
5dabfc78	36	int __init ext4_init_pageio(void)
bd2d0210	37	{
bd2d0210	38	io_end_cachep = KMEM_CACHE(ext4_io_end, SLAB_RECLAIM_ACCOUNT);
0058f965	39	if (io_end_cachep == NULL)
bd2d0210	40	return -ENOMEM;
bd2d0210 TT	41	return 0;
	42	}
	43
5dabfc78	44	void ext4_exit_pageio(void)
bd2d0210 TT	45	{
bd2d0210 TT	46	kmem_cache_destroy(io_end_cachep);
bd2d0210 TT	47	}
bd2d0210 TT	48
b0857d30 JK	49	/*
	50	* Print an buffer I/O error compatible with the fs/buffer.c. This
	51	* provides compatibility with dmesg scrapers that look for a specific
	52	* buffer I/O error message. We really need a unified error reporting
	53	* structure to userspace ala Digital Unix's uerf system, but it's
	54	* probably not going to happen in my lifetime, due to LKML politics...
	55	*/
	56	static void buffer_io_error(struct buffer_head *bh)
	57	{
	58	char b[BDEVNAME_SIZE];
e8974c39	59	printk_ratelimited(KERN_ERR "Buffer I/O error on device %s, logical block %llu\n",
b0857d30 JK	60	bdevname(bh->b_bdev, b),
	61	(unsigned long long)bh->b_blocknr);
	62	}
	63
	64	static void ext4_finish_bio(struct bio *bio)
	65	{
	66	int i;
	67	int error = !test_bit(BIO_UPTODATE, &bio->bi_flags);
	68
	69	for (i = 0; i < bio->bi_vcnt; i++) {
	70	struct bio_vec *bvec = &bio->bi_io_vec[i];
	71	struct page *page = bvec->bv_page;
	72	struct buffer_head bh, head;
	73	unsigned bio_start = bvec->bv_offset;
	74	unsigned bio_end = bio_start + bvec->bv_len;
	75	unsigned under_io = 0;
	76	unsigned long flags;
	77
	78	if (!page)
	79	continue;
	80
	81	if (error) {
	82	SetPageError(page);
	83	set_bit(AS_EIO, &page->mapping->flags);
	84	}
	85	bh = head = page_buffers(page);
	86	/*
	87	* We check all buffers in the page under BH_Uptodate_Lock
	88	* to avoid races with other end io clearing async_write flags
	89	*/
	90	local_irq_save(flags);
	91	bit_spin_lock(BH_Uptodate_Lock, &head->b_state);
	92	do {
	93	if (bh_offset(bh) < bio_start \|\|
	94	bh_offset(bh) + bh->b_size > bio_end) {
	95	if (buffer_async_write(bh))
	96	under_io++;
	97	continue;
	98	}
	99	clear_buffer_async_write(bh);
	100	if (error)
	101	buffer_io_error(bh);
	102	} while ((bh = bh->b_this_page) != head);
	103	bit_spin_unlock(BH_Uptodate_Lock, &head->b_state);
	104	local_irq_restore(flags);
	105	if (!under_io)
	106	end_page_writeback(page);
	107	}
	108	}
	109
97a851ed	110	static void ext4_release_io_end(ext4_io_end_t *io_end)
bd2d0210	111	{
b0857d30 JK	112	struct bio bio, next_bio;
b0857d30 JK	113
97a851ed JK	114	BUG_ON(!list_empty(&io_end->list));
97a851ed JK	115	BUG_ON(io_end->flag & EXT4_IO_END_UNWRITTEN);
6b523df4	116	WARN_ON(io_end->handle);
97a851ed JK	117
	118	if (atomic_dec_and_test(&EXT4_I(io_end->inode)->i_ioend_count))
	119	wake_up_all(ext4_ioend_wq(io_end->inode));
b0857d30 JK	120
	121	for (bio = io_end->bio; bio; bio = next_bio) {
	122	next_bio = bio->bi_private;
	123	ext4_finish_bio(bio);
	124	bio_put(bio);
	125	}
97a851ed JK	126	kmem_cache_free(io_end_cachep, io_end);
	127	}
	128
	129	static void ext4_clear_io_unwritten_flag(ext4_io_end_t *io_end)
	130	{
	131	struct inode *inode = io_end->inode;
82e54229	132
97a851ed JK	133	io_end->flag &= ~EXT4_IO_END_UNWRITTEN;
	134	/* Wake up anyone waiting on unwritten extent conversion */
	135	if (atomic_dec_and_test(&EXT4_I(inode)->i_unwritten))
	136	wake_up_all(ext4_ioend_wq(inode));
bd2d0210 TT	137	}
bd2d0210 TT	138
a115f749 JK	139	/*
	140	* Check a range of space and convert unwritten extents to written. Note that
	141	* we are protected from truncate touching same part of extent tree by the
	142	* fact that truncate code waits for all DIO to finish (thus exclusion from
	143	* direct IO is achieved) and also waits for PageWriteback bits. Thus we
	144	* cannot get to ext4_ext_truncate() before all IOs overlapping that range are
	145	* completed (happens from ext4_free_ioend()).
	146	*/
28a535f9	147	static int ext4_end_io(ext4_io_end_t *io)
bd2d0210 TT	148	{
	149	struct inode *inode = io->inode;
	150	loff_t offset = io->offset;
	151	ssize_t size = io->size;
6b523df4	152	handle_t *handle = io->handle;
bd2d0210 TT	153	int ret = 0;
	154
	155	ext4_debug("ext4_end_io_nolock: io 0x%p from inode %lu,list->next 0x%p,"
	156	"list->prev 0x%p\n",
	157	io, inode->i_ino, io->list.next, io->list.prev);
	158
6b523df4 JK	159	io->handle = NULL; /* Following call will use up the handle */
6b523df4 JK	160	ret = ext4_convert_unwritten_extents(handle, inode, offset, size);
bd2d0210	161	if (ret < 0) {
b82e384c TT	162	ext4_msg(inode->i_sb, KERN_EMERG,
	163	"failed to convert unwritten extents to written "
	164	"extents -- potential data loss! "
	165	"(inode %lu, offset %llu, size %zd, error %d)",
	166	inode->i_ino, offset, size, ret);
bd2d0210	167	}
97a851ed JK	168	ext4_clear_io_unwritten_flag(io);
97a851ed JK	169	ext4_release_io_end(io);
bd2d0210 TT	170	return ret;
	171	}
	172
2e8fa54e	173	static void dump_completed_IO(struct inode inode, struct list_head head)
28a535f9 DM	174	{
	175	#ifdef EXT4FS_DEBUG
	176	struct list_head cur, before, *after;
	177	ext4_io_end_t io, io0, *io1;
28a535f9	178
2e8fa54e	179	if (list_empty(head))
28a535f9	180	return;
28a535f9	181
2e8fa54e JK	182	ext4_debug("Dump inode %lu completed io list\n", inode->i_ino);
2e8fa54e JK	183	list_for_each_entry(io, head, list) {
28a535f9 DM	184	cur = &io->list;
	185	before = cur->prev;
	186	io0 = container_of(before, ext4_io_end_t, list);
	187	after = cur->next;
	188	io1 = container_of(after, ext4_io_end_t, list);
	189
	190	ext4_debug("io 0x%p from inode %lu,prev 0x%p,next 0x%p\n",
	191	io, inode->i_ino, io0, io1);
	192	}
	193	#endif
	194	}
	195
	196	/* Add the io_end to per-inode completed end_io list. */
97a851ed	197	static void ext4_add_complete_io(ext4_io_end_t *io_end)
bd2d0210	198	{
28a535f9 DM	199	struct ext4_inode_info *ei = EXT4_I(io_end->inode);
	200	struct workqueue_struct *wq;
	201	unsigned long flags;
	202
7b7a8665 CH	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);
d73d5046	206	spin_lock_irqsave(&ei->i_completed_io_lock, flags);
7b7a8665 CH	207	wq = EXT4_SB(io_end->inode->i_sb)->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);
28a535f9 DM	211	spin_unlock_irqrestore(&ei->i_completed_io_lock, flags);
28a535f9 DM	212	}
d73d5046	213
2e8fa54e JK	214	static int ext4_do_flush_completed_IO(struct inode *inode,
2e8fa54e JK	215	struct list_head *head)
28a535f9 DM	216	{
28a535f9 DM	217	ext4_io_end_t *io;
002bd7fa	218	struct list_head unwritten;
28a535f9 DM	219	unsigned long flags;
	220	struct ext4_inode_info *ei = EXT4_I(inode);
	221	int err, ret = 0;
	222
28a535f9	223	spin_lock_irqsave(&ei->i_completed_io_lock, flags);
2e8fa54e JK	224	dump_completed_IO(inode, head);
2e8fa54e JK	225	list_replace_init(head, &unwritten);
28a535f9 DM	226	spin_unlock_irqrestore(&ei->i_completed_io_lock, flags);
	227
	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);
	232
	233	err = ext4_end_io(io);
	234	if (unlikely(!ret && err))
	235	ret = err;
28a535f9 DM	236	}
	237	return ret;
	238	}
	239
	240	/*
2e8fa54e	241	* work on completed IO, to convert unwritten extents to extents
28a535f9	242	*/
2e8fa54e JK	243	void ext4_end_io_rsv_work(struct work_struct *work)
	244	{
	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);
	248	}
	249
bd2d0210 TT	250	ext4_io_end_t ext4_init_io_end(struct inode inode, gfp_t flags)
bd2d0210 TT	251	{
b17b35ec	252	ext4_io_end_t *io = kmem_cache_zalloc(io_end_cachep, flags);
bd2d0210	253	if (io) {
f7ad6d2e TT	254	atomic_inc(&EXT4_I(inode)->i_ioend_count);
f7ad6d2e TT	255	io->inode = inode;
bd2d0210	256	INIT_LIST_HEAD(&io->list);
97a851ed	257	atomic_set(&io->count, 1);
bd2d0210 TT	258	}
	259	return io;
	260	}
	261
97a851ed JK	262	void ext4_put_io_end_defer(ext4_io_end_t *io_end)
	263	{
	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);
	267	return;
	268	}
	269	ext4_add_complete_io(io_end);
	270	}
	271	}
	272
	273	int ext4_put_io_end(ext4_io_end_t *io_end)
	274	{
	275	int err = 0;
	276
	277	if (atomic_dec_and_test(&io_end->count)) {
	278	if (io_end->flag & EXT4_IO_END_UNWRITTEN) {
6b523df4 JK	279	err = ext4_convert_unwritten_extents(io_end->handle,
	280	io_end->inode, io_end->offset,
	281	io_end->size);
	282	io_end->handle = NULL;
97a851ed JK	283	ext4_clear_io_unwritten_flag(io_end);
	284	}
	285	ext4_release_io_end(io_end);
	286	}
	287	return err;
	288	}
	289
	290	ext4_io_end_t ext4_get_io_end(ext4_io_end_t io_end)
	291	{
	292	atomic_inc(&io_end->count);
	293	return io_end;
	294	}
	295
822dbba3	296	/* BIO completion function for page writeback */
bd2d0210 TT	297	static void ext4_end_bio(struct bio *bio, int error)
	298	{
	299	ext4_io_end_t *io_end = bio->bi_private;
d50bdd5a	300	sector_t bi_sector = bio->bi_sector;
bd2d0210 TT	301
bd2d0210 TT	302	BUG_ON(!io_end);
bd2d0210 TT	303	bio->bi_end_io = NULL;
	304	if (test_bit(BIO_UPTODATE, &bio->bi_flags))
	305	error = 0;
0058f965	306
f7ad6d2e	307	if (error) {
b0857d30 JK	308	struct inode *inode = io_end->inode;
b0857d30 JK	309
f7ad6d2e TT	310	ext4_warning(inode->i_sb, "I/O error writing to inode %lu "
	311	"(offset %llu size %ld starting block %llu)",
	312	inode->i_ino,
	313	(unsigned long long) io_end->offset,
	314	(long) io_end->size,
	315	(unsigned long long)
d50bdd5a	316	bi_sector >> (inode->i_blkbits - 9));
f7ad6d2e	317	}
822dbba3 JK	318
	319	if (io_end->flag & EXT4_IO_END_UNWRITTEN) {
	320	/*
	321	* Link bio into list hanging from io_end. We have to do it
	322	* atomically as bio completions can be racing against each
	323	* other.
	324	*/
	325	bio->bi_private = xchg(&io_end->bio, bio);
	326	ext4_put_io_end_defer(io_end);
	327	} else {
	328	/*
	329	* Drop io_end reference early. Inode can get freed once
	330	* we finish the bio.
	331	*/
	332	ext4_put_io_end_defer(io_end);
	333	ext4_finish_bio(bio);
	334	bio_put(bio);
	335	}
bd2d0210 TT	336	}
	337
	338	void ext4_io_submit(struct ext4_io_submit *io)
	339	{
	340	struct bio *bio = io->io_bio;
	341
	342	if (bio) {
	343	bio_get(io->io_bio);
	344	submit_bio(io->io_op, io->io_bio);
	345	BUG_ON(bio_flagged(io->io_bio, BIO_EOPNOTSUPP));
	346	bio_put(io->io_bio);
	347	}
7dc57615	348	io->io_bio = NULL;
97a851ed JK	349	}
	350
	351	void ext4_io_submit_init(struct ext4_io_submit *io,
	352	struct writeback_control *wbc)
	353	{
	354	io->io_op = (wbc->sync_mode == WB_SYNC_ALL ? WRITE_SYNC : WRITE);
	355	io->io_bio = NULL;
7dc57615	356	io->io_end = NULL;
bd2d0210 TT	357	}
bd2d0210 TT	358
97a851ed JK	359	static int io_submit_init_bio(struct ext4_io_submit *io,
97a851ed JK	360	struct buffer_head *bh)
bd2d0210	361	{
bd2d0210 TT	362	int nvecs = bio_get_nr_vecs(bh->b_bdev);
	363	struct bio *bio;
	364
275d3ba6	365	bio = bio_alloc(GFP_NOIO, min(nvecs, BIO_MAX_PAGES));
a1d8d9a7 TT	366	if (!bio)
a1d8d9a7 TT	367	return -ENOMEM;
bd2d0210 TT	368	bio->bi_sector = bh->b_blocknr * (bh->b_size >> 9);
bd2d0210 TT	369	bio->bi_bdev = bh->b_bdev;
bd2d0210	370	bio->bi_end_io = ext4_end_bio;
97a851ed	371	bio->bi_private = ext4_get_io_end(io->io_end);
bd2d0210	372	io->io_bio = bio;
bd2d0210 TT	373	io->io_next_block = bh->b_blocknr;
	374	return 0;
	375	}
	376
	377	static int io_submit_add_bh(struct ext4_io_submit *io,
bd2d0210	378	struct inode *inode,
bd2d0210 TT	379	struct buffer_head *bh)
bd2d0210 TT	380	{
bd2d0210 TT	381	int ret;
bd2d0210 TT	382
bd2d0210 TT	383	if (io->io_bio && bh->b_blocknr != io->io_next_block) {
	384	submit_and_retry:
	385	ext4_io_submit(io);
	386	}
	387	if (io->io_bio == NULL) {
97a851ed	388	ret = io_submit_init_bio(io, bh);
bd2d0210 TT	389	if (ret)
	390	return ret;
	391	}
97a851ed JK	392	ret = bio_add_page(io->io_bio, bh->b_page, bh->b_size, bh_offset(bh));
	393	if (ret != bh->b_size)
	394	goto submit_and_retry;
bd2d0210	395	io->io_next_block++;
bd2d0210 TT	396	return 0;
	397	}
	398
	399	int ext4_bio_write_page(struct ext4_io_submit *io,
	400	struct page *page,
	401	int len,
	402	struct writeback_control *wbc)
	403	{
	404	struct inode *inode = page->mapping->host;
0058f965	405	unsigned block_start, blocksize;
bd2d0210 TT	406	struct buffer_head bh, head;
bd2d0210 TT	407	int ret = 0;
0058f965	408	int nr_submitted = 0;
bd2d0210 TT	409
	410	blocksize = 1 << inode->i_blkbits;
	411
d50bdd5a	412	BUG_ON(!PageLocked(page));
bd2d0210	413	BUG_ON(PageWriteback(page));
bd2d0210	414
a54aa761 TT	415	set_page_writeback(page);
a54aa761 TT	416	ClearPageError(page);
bd2d0210	417
0058f965 JK	418	/*
	419	* In the first loop we prepare and mark buffers to submit. We have to
	420	* mark all buffers in the page before submitting so that
	421	* end_page_writeback() cannot be called from ext4_bio_end_io() when IO
	422	* on the first buffer finishes and we are still working on submitting
	423	* the second buffer.
	424	*/
	425	bh = head = page_buffers(page);
	426	do {
	427	block_start = bh_offset(bh);
bd2d0210	428	if (block_start >= len) {
5a0dc736 YY	429	/*
	430	* Comments copied from block_write_full_page_endio:
	431	*
	432	* The page straddles i_size. It must be zeroed out on
	433	* each and every writepage invocation because it may
	434	* be mmapped. "A file is mapped in multiples of the
	435	* page size. For a file that is not a multiple of
	436	* the page size, the remaining memory is zeroed when
	437	* mapped, and writes to that region are not written
	438	* out to the file."
	439	*/
0058f965 JK	440	zero_user_segment(page, block_start,
0058f965 JK	441	block_start + blocksize);
bd2d0210 TT	442	clear_buffer_dirty(bh);
	443	set_buffer_uptodate(bh);
	444	continue;
	445	}
8a850c3f JK	446	if (!buffer_dirty(bh) \|\| buffer_delay(bh) \|\|
	447	!buffer_mapped(bh) \|\| buffer_unwritten(bh)) {
	448	/* A hole? We can safely clear the dirty bit */
	449	if (!buffer_mapped(bh))
	450	clear_buffer_dirty(bh);
	451	if (io->io_bio)
	452	ext4_io_submit(io);
	453	continue;
	454	}
0058f965 JK	455	if (buffer_new(bh)) {
	456	clear_buffer_new(bh);
	457	unmap_underlying_metadata(bh->b_bdev, bh->b_blocknr);
	458	}
	459	set_buffer_async_write(bh);
	460	} while ((bh = bh->b_this_page) != head);
	461
	462	/* Now submit buffers to write */
	463	bh = head = page_buffers(page);
	464	do {
	465	if (!buffer_async_write(bh))
	466	continue;
97a851ed	467	ret = io_submit_add_bh(io, inode, bh);
bd2d0210 TT	468	if (ret) {
	469	/*
	470	* We only get here on ENOMEM. Not much else
	471	* we can do but mark the page as dirty, and
	472	* better luck next time.
	473	*/
1ae48a63	474	redirty_page_for_writepage(wbc, page);
bd2d0210 TT	475	break;
bd2d0210 TT	476	}
0058f965	477	nr_submitted++;
1ae48a63	478	clear_buffer_dirty(bh);
0058f965 JK	479	} while ((bh = bh->b_this_page) != head);
	480
	481	/* Error stopped previous loop? Clean up buffers... */
	482	if (ret) {
	483	do {
	484	clear_buffer_async_write(bh);
	485	bh = bh->b_this_page;
	486	} while (bh != head);
bd2d0210 TT	487	}
bd2d0210 TT	488	unlock_page(page);
0058f965 JK	489	/* Nothing submitted - we have to end page writeback */
	490	if (!nr_submitted)
	491	end_page_writeback(page);
bd2d0210 TT	492	return ret;
bd2d0210 TT	493	}