[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [PATCH v4 4/5] blockdev: honor bdrv_try_set_aio_context() context re
From: |
Max Reitz |
Subject: |
Re: [PATCH v4 4/5] blockdev: honor bdrv_try_set_aio_context() context requirements |
Date: |
Wed, 27 Nov 2019 18:10:29 +0100 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.2.2 |
On 21.11.19 14:57, Sergio Lopez wrote:
> bdrv_try_set_aio_context() requires that the old context is held, and
> the new context is not held. Fix all the occurrences where it's not
> done this way.
>
> Suggested-by: Max Reitz <address@hidden>
> Signed-off-by: Sergio Lopez <address@hidden>
> ---
> blockdev.c | 67 ++++++++++++++++++++++++++++++++++++++++++++++--------
> 1 file changed, 58 insertions(+), 9 deletions(-)
I wonder whether we even need to set the target’s context, because I
suppose it should be done automatically when it is attached to the
backup job with bdrv_attach_child() in bdrv_backup_top_append(). *shrug*
> diff --git a/blockdev.c b/blockdev.c
> index 152a0f7454..b0647d8d33 100644
> --- a/blockdev.c
> +++ b/blockdev.c
[...]
> @@ -1868,6 +1880,20 @@ static void drive_backup_prepare(BlkActionState
> *common, Error **errp)
> goto out;
> }
>
> + /* Honor bdrv_try_set_aio_context() context acquisition requirements. */
> + old_context = bdrv_get_aio_context(target_bs);
> + aio_context_release(aio_context);
> + aio_context_acquire(old_context);
> +
> + ret = bdrv_try_set_aio_context(target_bs, aio_context, errp);
> + if (ret < 0) {
> + aio_context_release(old_context);
> + return;
> + }
> +
> + aio_context_release(old_context);
> + aio_context_acquire(aio_context);
Would it work to put the error block after these two calls so it can
just goto out again? (Which would help if someone were to e.g.
introduce a new resource that is to be freed behind the out label.)
> if (set_backing_hd) {
> bdrv_set_backing_hd(target_bs, source, &local_err);
> if (local_err) {
[...]
> @@ -4001,14 +4046,18 @@ void qmp_blockdev_mirror(bool has_job_id, const char
> *job_id,
>
> zero_target = (sync == MIRROR_SYNC_MODE_FULL);
>
> + /* Honor bdrv_try_set_aio_context() context acquisition requirements. */
> + old_context = bdrv_get_aio_context(target_bs);
> aio_context = bdrv_get_aio_context(bs);
> - aio_context_acquire(aio_context);
> + aio_context_acquire(old_context);
>
> ret = bdrv_try_set_aio_context(target_bs, aio_context, errp);
> if (ret < 0) {
> goto out;
> }
>
> + aio_context_acquire(aio_context);
> +
old_context is never released here.
Max
> blockdev_mirror_common(has_job_id ? job_id : NULL, bs, target_bs,
> has_replaces, replaces, sync, backing_mode,
> zero_target, has_speed, speed,
>
signature.asc
Description: OpenPGP digital signature
- [PATCH v4 0/5] blockdev: avoid acquiring AioContext lock twice at do_drive_backup and do_blockdev_backup, Sergio Lopez, 2019/11/21
- [PATCH v4 1/5] blockdev: fix coding style issues in drive_backup_prepare, Sergio Lopez, 2019/11/21
- [PATCH v4 2/5] blockdev: unify qmp_drive_backup and drive-backup transaction paths, Sergio Lopez, 2019/11/21
- [PATCH v4 3/5] blockdev: unify qmp_blockdev_backup and blockdev-backup transaction paths, Sergio Lopez, 2019/11/21
- [PATCH v4 4/5] blockdev: honor bdrv_try_set_aio_context() context requirements, Sergio Lopez, 2019/11/21
- Re: [PATCH v4 4/5] blockdev: honor bdrv_try_set_aio_context() context requirements,
Max Reitz <=
- [PATCH v4 5/5] iotests: fix 141 after qmp_drive_backup with transactions, Sergio Lopez, 2019/11/21