Commit 7d2b4daa authored by Chris Mason's avatar Chris Mason
Browse files

Btrfs: Fix the multi-bio code to save the original bio for completion 



The multi-bio code is responsible for duplicating blocks in raid1 and
single spindle duplication.  It has counters to make sure all of
the locations for a given extent are properly written before io completion
is returned to the higher layers.

But, it didn't always complete the same bio it was given, sometimes a
clone was completed instead.  This lead to problems with the async
work queues because they saved a pointer to the bio in a struct off
bi_private.

The fix is to remember the original bio and only complete that one.

Signed-off-by: default avatarChris Mason <chris.mason@oracle.com>
parent ae01a0ab

fs/btrfs/volumes.c

+10 −1
Original line number Diff line number Diff line
@@ -2070,6 +2070,7 @@ static int end_bio_multi_stripe(struct bio *bio, 
#endif

{

	struct btrfs_multi_bio *multi = bio->bi_private;

	int is_orig_bio = 0;



#if LINUX_VERSION_CODE <= KERNEL_VERSION(2,6,23)

	if (bio->bi_size)
@@ -2078,7 +2079,14 @@ static int end_bio_multi_stripe(struct bio *bio, 
	if (err)

		atomic_inc(&multi->error);



	if (bio == multi->orig_bio)

		is_orig_bio = 1;



	if (atomic_dec_and_test(&multi->stripes_pending)) {

		if (!is_orig_bio) {

			bio_put(bio);

			bio = multi->orig_bio;

		}

		bio->bi_private = multi->private;

		bio->bi_end_io = multi->end_io;

		/* only send an error to the higher layers if it is
@@ -2101,7 +2109,7 @@ static int end_bio_multi_stripe(struct bio *bio, 
#else

		bio_endio(bio, err);

#endif

	} else {

	} else if (!is_orig_bio) {

		bio_put(bio);

	}

#if LINUX_VERSION_CODE <= KERNEL_VERSION(2,6,23)
@@ -2196,6 +2204,7 @@ int btrfs_map_bio(struct btrfs_root *root, int rw, struct bio *bio, 
	}

	multi->end_io = first_bio->bi_end_io;

	multi->private = first_bio->bi_private;

	multi->orig_bio = first_bio;

	atomic_set(&multi->stripes_pending, multi->num_stripes);



	while(dev_nr < total_devs) {

fs/btrfs/volumes.h

+1 −0
Original line number Diff line number Diff line
@@ -95,6 +95,7 @@ struct btrfs_bio_stripe { 
struct btrfs_multi_bio {

	atomic_t stripes_pending;

	bio_end_io_t *end_io;

	struct bio *orig_bio;

	void *private;

	atomic_t error;

	int max_errors;

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