OK, after a bit more staring I believe the correct fix is the following.
Fengguang, Please try this one?
Regards,
Muthu
------------
In btrfs_end_bio(), we increment bi_remaining if is_orig_bio. If not,
we restore the orig_bio but failed to increment bi_remaining for
orig_bio, which triggers a BUG_ON later when bio_endio is called. Fix
is to increment bi_remaining when we restore the orig bio as well.
Reported-by: fengguang.wu@xxxxxxxxx
CC: Kent Overstreet <kmo@xxxxxxxxxxxxx>
CC: Jens Axboe <axboe@xxxxxxxxx>
CC: Chris Mason <clm@fv
Signed-off-by: Muthukumar Ratty <muthur@xxxxxxxxx>
----------------
fs/btrfs/volumes.c | 4 ++--
1 files changed, 2 insertions(+), 2 deletions(-)
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 37972d5..2011cc0 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -5297,9 +5297,9 @@ static void btrfs_end_bio(struct bio *bio, int err)
if (!is_orig_bio) {
bio_put(bio);
bio = bbio->orig_bio;
- } else {
- atomic_inc(&bio->bi_remaining);
}
+ atomic_inc(&bio->bi_remaining);
+
bio->bi_private = bbio->private;
bio->bi_end_io = bbio->end_io;
btrfs_io_bio(bio)->mirror_num = bbio->mirror_num;
--------------------------
On Mon, Jan 6, 2014 at 2:10 PM, Kent Overstreet <kmo@xxxxxxxxxxxxx> wrote:
> Chris, the patch below seems to be incorrect - with it we get hangs, so
> bi_remaining (probably) isn't getting decremented when it should be. You sent
> Jens fixes for btrfs which I somehow lost when I rebased, do you remember how
> this is supposed to work? Looking at the code I'm not quite sure what's going on
> here.
>
> On Fri, Jan 03, 2014 at 11:51:31AM -0800, Muthu Kumar wrote:
>> Looks like Kent missed the btrfs endio in the original commit. How
>> about this patch:
>>
>> ---------
>>
>> In btrfs_end_bio, call bio_endio_nodec on the restored bio so the
>> bi_remaining is accounted for correctly.
>>
>> Reported-by: fengguang.wu@xxxxxxxxx
>> Cc: Kent Overstreet <kmo@xxxxxxxxxxxxx>
>> CC: Jens Axboe <axboe@xxxxxxxxx>
>> Signed-off-by: Muthukumar Ratty <muthur@xxxxxxxxx>
>> --------
>>
>> fs/btrfs/volumes.c | 6 +++++-
>> 1 files changed, 5 insertions(+), 1 deletions(-)
>>
>> diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
>> index f2130de..edfed52 100644
>> --- a/fs/btrfs/volumes.c
>> +++ b/fs/btrfs/volumes.c
>> @@ -5316,7 +5316,11 @@ static void btrfs_end_bio(struct bio *bio, int err)
>> }
>> kfree(bbio);
>>
>> - bio_endio(bio, err);
>> + /*
>> + * Call endio_nodec on the restored bio so the bi_remaining is
>> + * accounted for correctly
>> + */
>> + bio_endio_nodec(bio, err);
>> } else if (!is_orig_bio) {
>> bio_put(bio);
>> }
--
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