On Tue, 13 Aug 2013 17:50:51 +0400, Vyacheslav Dubeyko wrote:
> From: Vyacheslav Dubeyko <slava@xxxxxxxxxxx>
> Subject: [PATCH v3 2/2] nilfs2: fix issue with counting number of bio requests for BIO_EOPNOTSUPP error detection
>
> This patch fixes the issue with improper counting number of
> flying bio requests for BIO_EOPNOTSUPP error detection case.
>
> The sb_nbio must be incremented exactly the same number of times as
> complete() function was called (or will be called) because
> nilfs_segbuf_wait() will call wail_for_completion() for the number of
> times set to sb_nbio:
>
> do {
> wait_for_completion(&segbuf->sb_bio_event);
> } while (--segbuf->sb_nbio > 0);
>
> Two functions complete() and wait_for_completion() must be called the
> same number of times for the same sb_bio_event. Otherwise,
> wait_for_completion() will hang or leak.
>
> Signed-off-by: Vyacheslav Dubeyko <slava@xxxxxxxxxxx>
> CC: Ryusuke Konishi <konishi.ryusuke@xxxxxxxxxxxxx>
Acked-by: Ryusuke Konishi <konishi.ryusuke@xxxxxxxxxxxxx>
Tested-by: Ryusuke Konishi <konishi.ryusuke@xxxxxxxxxxxxx>
I confirmed that this fixes the leak of wait_for_completion() for the
BIO_EOPNOTSUPP error detection case.
Andrew, please send this upstream along with the companion patch
titled "nilfs2: remove double bio_put() in nilfs_end_bio_write() for
BIO_EOPNOTSUPP error".
Thanks,
Ryusuke Konishi
> CC: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
> ---
> fs/nilfs2/segbuf.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/fs/nilfs2/segbuf.c b/fs/nilfs2/segbuf.c
> index 5bacf46..2d8be51 100644
> --- a/fs/nilfs2/segbuf.c
> +++ b/fs/nilfs2/segbuf.c
> @@ -376,12 +376,12 @@ static int nilfs_segbuf_submit_bio(struct nilfs_segment_buffer *segbuf,
> bio->bi_private = segbuf;
> bio_get(bio);
> submit_bio(mode, bio);
> + segbuf->sb_nbio++;
> if (bio_flagged(bio, BIO_EOPNOTSUPP)) {
> bio_put(bio);
> err = -EOPNOTSUPP;
> goto failed;
> }
> - segbuf->sb_nbio++;
> bio_put(bio);
>
> wi->bio = NULL;
> --
> 1.7.9.5
>
>
>
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