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ext4: revert "ext4: use io_end for multiple bios"
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This reverts commit 4eec708.

Multiple users have reported crashes which is apparently caused by
this commit.  Thanks to Dmitry Monakhov for bisecting it.

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Cc: Dmitry Monakhov <dmonakhov@openvz.org>
Cc: Jan Kara <jack@suse.cz>
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Theodore Ts'o committed May 11, 2013
1 parent e615573 commit a549984
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Showing 3 changed files with 85 additions and 129 deletions.
8 changes: 2 additions & 6 deletions fs/ext4/ext4.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -209,7 +209,6 @@ 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 @@ -2651,14 +2650,11 @@ 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: 38 additions & 47 deletions fs/ext4/inode.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -1487,10 +1487,7 @@ 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);
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;
memset(&io_submit, 0, sizeof(io_submit));
/*
* 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 @@ -1578,8 +1575,6 @@ 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 @@ -2238,16 +2233,9 @@ static int ext4_writepage(struct page *page,
*/
return __ext4_journalled_writepage(page, len);

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;
}
memset(&io_submit, 0, sizeof(io_submit));
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 @@ -3078,27 +3066,35 @@ 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 just return */
if (!io_end) {
inode_dio_done(inode);
if (is_async)
aio_complete(iocb, ret, 0);
return;
}
/* if not async direct IO or dio with 0 bytes write, just return */
if (!io_end || !size)
goto out;

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_put_io_end_defer(io_end);

ext4_add_complete_io(io_end);
}

/*
Expand Down Expand Up @@ -3132,7 +3128,6 @@ 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 @@ -3171,16 +3166,13 @@ 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)) {
io_end = ext4_init_io_end(inode, GFP_NOFS);
ext4_io_end_t *io_end = ext4_init_io_end(inode, GFP_NOFS);
if (!io_end) {
ret = -ENOMEM;
goto retake_lock;
}
io_end->flag |= EXT4_IO_END_DIRECT;
/*
* Grab reference for DIO. Will be dropped in ext4_end_io_dio()
*/
iocb->private = ext4_get_io_end(io_end);
iocb->private = io_end;
/*
* we save the io structure for current async direct
* IO, so that later ext4_map_blocks() could flag the
Expand All @@ -3204,27 +3196,26 @@ static ssize_t ext4_ext_direct_IO(int rw, struct kiocb *iocb,
NULL,
dio_flags);

if (iocb->private)
ext4_inode_aio_set(inode, NULL);
/*
* 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.
* 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.
*/
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,
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,
EXT4_STATE_DIO_UNWRITTEN)) {
int err;
/*
Expand Down
121 changes: 45 additions & 76 deletions fs/ext4/page-io.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -61,28 +61,15 @@ void ext4_ioend_shutdown(struct inode *inode)
cancel_work_sync(&EXT4_I(inode)->i_unwritten_work);
}

static void ext4_release_io_end(ext4_io_end_t *io_end)
void ext4_free_io_end(ext4_io_end_t *io)
{
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);
}

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

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));
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. */
Expand All @@ -105,8 +92,13 @@ static int ext4_end_io(ext4_io_end_t *io)
"(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);
/* 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;
}

Expand Down Expand Up @@ -137,7 +129,7 @@ static void dump_completed_IO(struct inode *inode)
}

/* Add the io_end to per-inode completed end_io list. */
static void ext4_add_complete_io(ext4_io_end_t *io_end)
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 @@ -174,6 +166,8 @@ 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 @@ -205,43 +199,10 @@ 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 @@ -324,7 +285,12 @@ static void ext4_end_bio(struct bio *bio, int error)
bi_sector >> (inode->i_blkbits - 9));
}

ext4_put_io_end_defer(io_end);
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)
Expand All @@ -338,37 +304,40 @@ void ext4_io_submit(struct ext4_io_submit *io)
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_op = 0;
io->io_end = NULL;
}

static int io_submit_init_bio(struct ext4_io_submit *io,
struct buffer_head *bh)
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;
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_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;
Expand All @@ -379,18 +348,18 @@ static int io_submit_add_bh(struct ext4_io_submit *io,
ext4_io_submit(io);
}
if (io->io_bio == NULL) {
ret = io_submit_init_bio(io, bh);
ret = io_submit_init(io, inode, wbc, 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 (test_clear_buffer_uninit(bh))
ext4_set_io_unwritten_flag(inode, io_end);
io_end->size += bh->b_size;
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;
}

Expand Down Expand Up @@ -462,7 +431,7 @@ int ext4_bio_write_page(struct ext4_io_submit *io,
do {
if (!buffer_async_write(bh))
continue;
ret = io_submit_add_bh(io, inode, bh);
ret = io_submit_add_bh(io, inode, wbc, bh);
if (ret) {
/*
* We only get here on ENOMEM. Not much else
Expand Down

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