Skip to content

Commit

Permalink
ext4: use io_end for multiple bios
Browse files Browse the repository at this point in the history 
Change writeback path to create just one io_end structure for the
extent to which we submit IO and share it among bios writing that
extent. This prevents needless splitting and joining of unwritten
extents when they cannot be submitted as a single bio.

Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Reviewed-by: Dmitry Monakhov <dmonakhov@openvz.org>
Reviewed-by: Zheng Liu <wenqing.lz@taobao.com>
  • Loading branch information
Jan Kara authored and Theodore Ts'o committed Apr 12, 2013
1 parent 0058f96 commit 4eec708
Show file tree
Hide file tree
Showing 3 changed files with 128 additions and 86 deletions.
8 changes: 6 additions & 2 deletions fs/ext4/ext4.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -209,6 +209,7 @@ typedef struct ext4_io_end {
ssize_t size; /* size of the extent */
struct kiocb *iocb; /* iocb struct for AIO */
int result; /* error value for AIO */
atomic_t count; /* reference counter */
} ext4_io_end_t;

struct ext4_io_submit {
Expand Down Expand Up @@ -2627,11 +2628,14 @@ extern int ext4_move_extents(struct file *o_filp, struct file *d_filp,

/* page-io.c */
extern int __init ext4_init_pageio(void);
extern void ext4_add_complete_io(ext4_io_end_t *io_end);
extern void ext4_exit_pageio(void);
extern void ext4_ioend_shutdown(struct inode *);
extern void ext4_free_io_end(ext4_io_end_t *io);
extern ext4_io_end_t *ext4_init_io_end(struct inode *inode, gfp_t flags);
extern ext4_io_end_t *ext4_get_io_end(ext4_io_end_t *io_end);
extern int ext4_put_io_end(ext4_io_end_t *io_end);
extern void ext4_put_io_end_defer(ext4_io_end_t *io_end);
extern void ext4_io_submit_init(struct ext4_io_submit *io,
struct writeback_control *wbc);
extern void ext4_end_io_work(struct work_struct *work);
extern void ext4_io_submit(struct ext4_io_submit *io);
extern int ext4_bio_write_page(struct ext4_io_submit *io,
Expand Down
85 changes: 47 additions & 38 deletions fs/ext4/inode.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -1483,7 +1483,10 @@ static int mpage_da_submit_io(struct mpage_da_data *mpd,
struct ext4_io_submit io_submit;

BUG_ON(mpd->next_page <= mpd->first_page);
memset(&io_submit, 0, sizeof(io_submit));
ext4_io_submit_init(&io_submit, mpd->wbc);
io_submit.io_end = ext4_init_io_end(inode, GFP_NOFS);
if (!io_submit.io_end)
return -ENOMEM;
/*
* We need to start from the first_page to the next_page - 1
* to make sure we also write the mapped dirty buffer_heads.
Expand Down Expand Up @@ -1571,6 +1574,8 @@ static int mpage_da_submit_io(struct mpage_da_data *mpd,
pagevec_release(&pvec);
}
ext4_io_submit(&io_submit);
/* Drop io_end reference we got from init */
ext4_put_io_end_defer(io_submit.io_end);
return ret;
}

Expand Down Expand Up @@ -2229,9 +2234,16 @@ static int ext4_writepage(struct page *page,
*/
return __ext4_journalled_writepage(page, len);

memset(&io_submit, 0, sizeof(io_submit));
ext4_io_submit_init(&io_submit, wbc);
io_submit.io_end = ext4_init_io_end(inode, GFP_NOFS);
if (!io_submit.io_end) {
redirty_page_for_writepage(wbc, page);
return -ENOMEM;
}
ret = ext4_bio_write_page(&io_submit, page, len, wbc);
ext4_io_submit(&io_submit);
/* Drop io_end reference we got from init */
ext4_put_io_end_defer(io_submit.io_end);
return ret;
}

Expand Down Expand Up @@ -3062,35 +3074,27 @@ static void ext4_end_io_dio(struct kiocb *iocb, loff_t offset,
struct inode *inode = file_inode(iocb->ki_filp);
ext4_io_end_t *io_end = iocb->private;

/* if not async direct IO or dio with 0 bytes write, just return */
if (!io_end || !size)
goto out;
/* if not async direct IO just return */
if (!io_end) {
inode_dio_done(inode);
if (is_async)
aio_complete(iocb, ret, 0);
return;
}

ext_debug("ext4_end_io_dio(): io_end 0x%p "
"for inode %lu, iocb 0x%p, offset %llu, size %zd\n",
iocb->private, io_end->inode->i_ino, iocb, offset,
size);

iocb->private = NULL;

/* if not aio dio with unwritten extents, just free io and return */
if (!(io_end->flag & EXT4_IO_END_UNWRITTEN)) {
ext4_free_io_end(io_end);
out:
inode_dio_done(inode);
if (is_async)
aio_complete(iocb, ret, 0);
return;
}

io_end->offset = offset;
io_end->size = size;
if (is_async) {
io_end->iocb = iocb;
io_end->result = ret;
}

ext4_add_complete_io(io_end);
ext4_put_io_end_defer(io_end);
}

/*
Expand Down Expand Up @@ -3124,6 +3128,7 @@ static ssize_t ext4_ext_direct_IO(int rw, struct kiocb *iocb,
get_block_t *get_block_func = NULL;
int dio_flags = 0;
loff_t final_size = offset + count;
ext4_io_end_t *io_end = NULL;

/* Use the old path for reads and writes beyond i_size. */
if (rw != WRITE || final_size > inode->i_size)
Expand Down Expand Up @@ -3162,13 +3167,16 @@ static ssize_t ext4_ext_direct_IO(int rw, struct kiocb *iocb,
iocb->private = NULL;
ext4_inode_aio_set(inode, NULL);
if (!is_sync_kiocb(iocb)) {
ext4_io_end_t *io_end = ext4_init_io_end(inode, GFP_NOFS);
io_end = ext4_init_io_end(inode, GFP_NOFS);
if (!io_end) {
ret = -ENOMEM;
goto retake_lock;
}
io_end->flag |= EXT4_IO_END_DIRECT;
iocb->private = io_end;
/*
* Grab reference for DIO. Will be dropped in ext4_end_io_dio()
*/
iocb->private = ext4_get_io_end(io_end);
/*
* we save the io structure for current async direct
* IO, so that later ext4_map_blocks() could flag the
Expand All @@ -3192,26 +3200,27 @@ static ssize_t ext4_ext_direct_IO(int rw, struct kiocb *iocb,
NULL,
dio_flags);

if (iocb->private)
ext4_inode_aio_set(inode, NULL);
/*
* The io_end structure takes a reference to the inode, that
* structure needs to be destroyed and the reference to the
* inode need to be dropped, when IO is complete, even with 0
* byte write, or failed.
*
* In the successful AIO DIO case, the io_end structure will
* be destroyed and the reference to the inode will be dropped
* after the end_io call back function is called.
*
* In the case there is 0 byte write, or error case, since VFS
* direct IO won't invoke the end_io call back function, we
* need to free the end_io structure here.
* Put our reference to io_end. This can free the io_end structure e.g.
* in sync IO case or in case of error. It can even perform extent
* conversion if all bios we submitted finished before we got here.
* Note that in that case iocb->private can be already set to NULL
* here.
*/
if (ret != -EIOCBQUEUED && ret <= 0 && iocb->private) {
ext4_free_io_end(iocb->private);
iocb->private = NULL;
} else if (ret > 0 && !overwrite && ext4_test_inode_state(inode,
if (io_end) {
ext4_inode_aio_set(inode, NULL);
ext4_put_io_end(io_end);
/*
* In case of error or no write ext4_end_io_dio() was not
* called so we have to put iocb's reference.
*/
if (ret <= 0 && ret != -EIOCBQUEUED) {
WARN_ON(iocb->private != io_end);
ext4_put_io_end(io_end);
iocb->private = NULL;
}
}
if (ret > 0 && !overwrite && ext4_test_inode_state(inode,
EXT4_STATE_DIO_UNWRITTEN)) {
int err;
/*
Expand Down
121 changes: 75 additions & 46 deletions fs/ext4/page-io.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -61,17 +61,28 @@ void ext4_ioend_shutdown(struct inode *inode)
cancel_work_sync(&EXT4_I(inode)->i_unwritten_work);
}

void ext4_free_io_end(ext4_io_end_t *io)
static void ext4_release_io_end(ext4_io_end_t *io_end)
{
int i;
BUG_ON(!list_empty(&io_end->list));
BUG_ON(io_end->flag & EXT4_IO_END_UNWRITTEN);

if (atomic_dec_and_test(&EXT4_I(io_end->inode)->i_ioend_count))
wake_up_all(ext4_ioend_wq(io_end->inode));
if (io_end->flag & EXT4_IO_END_DIRECT)
inode_dio_done(io_end->inode);
if (io_end->iocb)
aio_complete(io_end->iocb, io_end->result, 0);
kmem_cache_free(io_end_cachep, io_end);
}

BUG_ON(!io);
BUG_ON(!list_empty(&io->list));
BUG_ON(io->flag & EXT4_IO_END_UNWRITTEN);
static void ext4_clear_io_unwritten_flag(ext4_io_end_t *io_end)
{
struct inode *inode = io_end->inode;

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);
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. */
Expand All @@ -94,13 +105,8 @@ static int ext4_end_io(ext4_io_end_t *io)
"(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);
ext4_clear_io_unwritten_flag(io);
ext4_release_io_end(io);
return ret;
}

Expand Down Expand Up @@ -131,7 +137,7 @@ static void dump_completed_IO(struct inode *inode)
}

/* Add the io_end to per-inode completed end_io list. */
void ext4_add_complete_io(ext4_io_end_t *io_end)
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;
Expand Down Expand Up @@ -168,8 +174,6 @@ static int ext4_do_flush_completed_IO(struct inode *inode)
err = ext4_end_io(io);
if (unlikely(!ret && err))
ret = err;
io->flag &= ~EXT4_IO_END_UNWRITTEN;
ext4_free_io_end(io);
}
return ret;
}
Expand Down Expand Up @@ -201,10 +205,43 @@ ext4_io_end_t *ext4_init_io_end(struct inode *inode, gfp_t flags)
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->inode,
io_end->offset, io_end->size);
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;
}

/*
* Print an buffer I/O error compatible with the fs/buffer.c. This
* provides compatibility with dmesg scrapers that look for a specific
Expand Down Expand Up @@ -287,12 +324,7 @@ static void ext4_end_bio(struct bio *bio, int error)
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);
ext4_put_io_end_defer(io_end);
}

void ext4_io_submit(struct ext4_io_submit *io)
Expand All @@ -306,40 +338,37 @@ void ext4_io_submit(struct ext4_io_submit *io)
bio_put(io->io_bio);
}
io->io_bio = NULL;
io->io_op = 0;
}

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(struct ext4_io_submit *io,
struct inode *inode,
struct writeback_control *wbc,
struct buffer_head *bh)
static int io_submit_init_bio(struct ext4_io_submit *io,
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);

bio->bi_private = ext4_get_io_end(io->io_end);
if (!io->io_end->size)
io->io_end->offset = (bh->b_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;
Expand All @@ -350,18 +379,18 @@ static int io_submit_add_bh(struct ext4_io_submit *io,
ext4_io_submit(io);
}
if (io->io_bio == NULL) {
ret = io_submit_init(io, inode, wbc, bh);
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_end = io->io_end;
if (buffer_uninit(bh))
ext4_set_io_unwritten_flag(inode, io_end);
io->io_end->size += bh->b_size;
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;
}

Expand Down Expand Up @@ -433,7 +462,7 @@ int ext4_bio_write_page(struct ext4_io_submit *io,
do {
if (!buffer_async_write(bh))
continue;
ret = io_submit_add_bh(io, inode, wbc, bh);
ret = io_submit_add_bh(io, inode, bh);
if (ret) {
/*
* We only get here on ENOMEM. Not much else
Expand Down

0 comments on commit 4eec708

Please sign in to comment.