Commit 4591c3ef authored by Qu Wenruo's avatar Qu Wenruo Committed by David Sterba
Browse files

btrfs: make sure all btrfs_bio::end_io are called in task context 



[BACKGROUND]
Btrfs has a lot of different bi_end_io functions, to handle different
raid profiles. But they introduced a lot of different contexts for
btrfs_bio::end_io() calls:

- Simple read bios
  Run in task context, backed by either endio_meta_workers or
  endio_workers.

- Simple write bios
  Run in IRQ context.

- RAID56 write or rebuild bios
  Run in task context, backed by rmw_workers.

- Mirrored write bios
  Run in irq context.

This is inconsistent, and contributes to the number of workqueues used
in btrfs.

[ENHANCEMENT]
Make all the above bios call their btrfs_bio::end_io() in task context,
backed by either endio_meta_workers for metadata, or endio_workers for
data.

For simple write bios, merge the handling into simple_end_io_work().

For mirrored write bios, it will be a little more complex, since both
the original or the cloned bios can run the final btrfs_bio::end_io().

Here we make sure the cloned bios are using btrfs_bioset, to reuse the
end_io_work, and run both original and cloned work inside the workqueue.

Add extra ASSERT()s to make sure btrfs_bio_end_io() is running in task
context.

This not only unifies the context for btrfs_bio::end_io() functions, but
also opens a new door for further btrfs_bio::end_io() related cleanups.

Signed-off-by: default avatarQu Wenruo <wqu@suse.com>
Reviewed-by: default avatarDavid Sterba <dsterba@suse.com>
Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
parent 81cea6cd

fs/btrfs/bio.c

+46 −18
Original line number Diff line number Diff line
@@ -102,6 +102,9 @@ static struct btrfs_bio *btrfs_split_bio(struct btrfs_fs_info *fs_info, 


void btrfs_bio_end_io(struct btrfs_bio *bbio, blk_status_t status)

{

	/* Make sure we're already in task context. */

	ASSERT(in_task());



	bbio->bio.bi_status = status;

	if (bbio->bio.bi_pool == &btrfs_clone_bioset) {

		struct btrfs_bio *orig_bbio = bbio->private;
@@ -318,14 +321,19 @@ static struct workqueue_struct *btrfs_end_io_wq(const struct btrfs_fs_info *fs_i 
	return fs_info->endio_workers;

}



static void btrfs_end_bio_work(struct work_struct *work)

static void simple_end_io_work(struct work_struct *work)

{

	struct btrfs_bio *bbio = container_of(work, struct btrfs_bio, end_io_work);

	struct bio *bio = &bbio->bio;



	if (bio_op(bio) == REQ_OP_READ) {

		/* Metadata reads are checked and repaired by the submitter. */

		if (is_data_bbio(bbio))

		btrfs_check_read_bio(bbio, bbio->bio.bi_private);

	else

			return btrfs_check_read_bio(bbio, bbio->bio.bi_private);

		return btrfs_bio_end_io(bbio, bbio->bio.bi_status);

	}

	if (bio_is_zone_append(bio) && !bio->bi_status)

		btrfs_record_physical_zoned(bbio);

	btrfs_bio_end_io(bbio, bbio->bio.bi_status);

}
@@ -340,14 +348,8 @@ static void btrfs_simple_end_io(struct bio *bio) 
	if (bio->bi_status)

		btrfs_log_dev_io_error(bio, dev);



	if (bio_op(bio) == REQ_OP_READ) {

		INIT_WORK(&bbio->end_io_work, btrfs_end_bio_work);

	INIT_WORK(&bbio->end_io_work, simple_end_io_work);

	queue_work(btrfs_end_io_wq(fs_info, bio), &bbio->end_io_work);

	} else {

		if (bio_is_zone_append(bio) && !bio->bi_status)

			btrfs_record_physical_zoned(bbio);

		btrfs_bio_end_io(bbio, bbio->bio.bi_status);

	}

}



static void btrfs_raid56_end_io(struct bio *bio)
@@ -355,6 +357,9 @@ static void btrfs_raid56_end_io(struct bio *bio) 
	struct btrfs_io_context *bioc = bio->bi_private;

	struct btrfs_bio *bbio = btrfs_bio(bio);



	/* RAID56 endio is always handled in workqueue. */

	ASSERT(in_task());



	btrfs_bio_counter_dec(bioc->fs_info);

	bbio->mirror_num = bioc->mirror_num;

	if (bio_op(bio) == REQ_OP_READ && is_data_bbio(bbio))
@@ -365,11 +370,12 @@ static void btrfs_raid56_end_io(struct bio *bio) 
	btrfs_put_bioc(bioc);

}



static void btrfs_orig_write_end_io(struct bio *bio)

static void orig_write_end_io_work(struct work_struct *work)

{

	struct btrfs_bio *bbio = container_of(work, struct btrfs_bio, end_io_work);

	struct bio *bio = &bbio->bio;

	struct btrfs_io_stripe *stripe = bio->bi_private;

	struct btrfs_io_context *bioc = stripe->bioc;

	struct btrfs_bio *bbio = btrfs_bio(bio);



	btrfs_bio_counter_dec(bioc->fs_info);
@@ -394,8 +400,18 @@ static void btrfs_orig_write_end_io(struct bio *bio) 
	btrfs_put_bioc(bioc);

}



static void btrfs_clone_write_end_io(struct bio *bio)

static void btrfs_orig_write_end_io(struct bio *bio)

{

	struct btrfs_bio *bbio = btrfs_bio(bio);



	INIT_WORK(&bbio->end_io_work, orig_write_end_io_work);

	queue_work(btrfs_end_io_wq(bbio->inode->root->fs_info, bio), &bbio->end_io_work);

}



static void clone_write_end_io_work(struct work_struct *work)

{

	struct btrfs_bio *bbio = container_of(work, struct btrfs_bio, end_io_work);

	struct bio *bio = &bbio->bio;

	struct btrfs_io_stripe *stripe = bio->bi_private;



	if (bio->bi_status) {
@@ -410,6 +426,14 @@ static void btrfs_clone_write_end_io(struct bio *bio) 
	bio_put(bio);

}



static void btrfs_clone_write_end_io(struct bio *bio)

{

	struct btrfs_bio *bbio = btrfs_bio(bio);



	INIT_WORK(&bbio->end_io_work, clone_write_end_io_work);

	queue_work(btrfs_end_io_wq(bbio->inode->root->fs_info, bio), &bbio->end_io_work);

}



static void btrfs_submit_dev_bio(struct btrfs_device *dev, struct bio *bio)

{

	if (!dev || !dev->bdev ||
@@ -456,6 +480,7 @@ static void btrfs_submit_dev_bio(struct btrfs_device *dev, struct bio *bio) 
static void btrfs_submit_mirrored_bio(struct btrfs_io_context *bioc, int dev_nr)

{

	struct bio *orig_bio = bioc->orig_bio, *bio;

	struct btrfs_bio *orig_bbio = btrfs_bio(orig_bio);



	ASSERT(bio_op(orig_bio) != REQ_OP_READ);
@@ -464,8 +489,11 @@ static void btrfs_submit_mirrored_bio(struct btrfs_io_context *bioc, int dev_nr) 
		bio = orig_bio;

		bio->bi_end_io = btrfs_orig_write_end_io;

	} else {

		bio = bio_alloc_clone(NULL, orig_bio, GFP_NOFS, &fs_bio_set);

		/* We need to use endio_work to run end_io in task context. */

		bio = bio_alloc_clone(NULL, orig_bio, GFP_NOFS, &btrfs_bioset);

		bio_inc_remaining(orig_bio);

		btrfs_bio_init(btrfs_bio(bio), orig_bbio->inode,

			       orig_bbio->file_offset, NULL, NULL);

		bio->bi_end_io = btrfs_clone_write_end_io;

	}