* [PATCH] Btrfs: stop all workers before cleaning up roots
@ 2013-05-30 20:58 Josef Bacik
2013-08-01 14:05 ` Alex Lyakas
0 siblings, 1 reply; 3+ messages in thread
From: Josef Bacik @ 2013-05-30 20:58 UTC (permalink / raw)
To: linux-btrfs
Dave reported a panic because the extent_root->commit_root was NULL in the
caching kthread. That is because we just unset it in free_root_pointers, which
is not the correct thing to do, we have to either wait for the caching kthread
to complete or hold the extent_commit_sem lock so we know the thread has exited.
This patch makes the kthreads all stop first and then we do our cleanup. This
should fix the race. Thanks,
Reported-by: David Sterba <dsterba@suse.cz>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
---
fs/btrfs/disk-io.c | 6 +++---
1 files changed, 3 insertions(+), 3 deletions(-)
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index 2b53afd..77cb566 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -3547,13 +3547,13 @@ int close_ctree(struct btrfs_root *root)
btrfs_free_block_groups(fs_info);
- free_root_pointers(fs_info, 1);
+ btrfs_stop_all_workers(fs_info);
del_fs_roots(fs_info);
- iput(fs_info->btree_inode);
+ free_root_pointers(fs_info, 1);
- btrfs_stop_all_workers(fs_info);
+ iput(fs_info->btree_inode);
#ifdef CONFIG_BTRFS_FS_CHECK_INTEGRITY
if (btrfs_test_opt(root, CHECK_INTEGRITY))
--
1.7.7.6
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] Btrfs: stop all workers before cleaning up roots
2013-05-30 20:58 [PATCH] Btrfs: stop all workers before cleaning up roots Josef Bacik
@ 2013-08-01 14:05 ` Alex Lyakas
2013-08-05 15:09 ` Josef Bacik
0 siblings, 1 reply; 3+ messages in thread
From: Alex Lyakas @ 2013-08-01 14:05 UTC (permalink / raw)
To: Josef Bacik; +Cc: linux-btrfs
Hi Josef,
On Thu, May 30, 2013 at 11:58 PM, Josef Bacik <jbacik@fusionio.com> wrote:
> Dave reported a panic because the extent_root->commit_root was NULL in the
> caching kthread. That is because we just unset it in free_root_pointers, which
> is not the correct thing to do, we have to either wait for the caching kthread
> to complete or hold the extent_commit_sem lock so we know the thread has exited.
> This patch makes the kthreads all stop first and then we do our cleanup. This
> should fix the race. Thanks,
>
> Reported-by: David Sterba <dsterba@suse.cz>
> Signed-off-by: Josef Bacik <jbacik@fusionio.com>
> ---
> fs/btrfs/disk-io.c | 6 +++---
> 1 files changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
> index 2b53afd..77cb566 100644
> --- a/fs/btrfs/disk-io.c
> +++ b/fs/btrfs/disk-io.c
> @@ -3547,13 +3547,13 @@ int close_ctree(struct btrfs_root *root)
>
> btrfs_free_block_groups(fs_info);
do you think it would be safer to stop all workers first and make sure
they are stopped, then do btrfs_free_block_groups()? I see, for
example, that btrfs_free_block_groups() checks:
if (block_group->cached == BTRFS_CACHE_STARTED)
which could be perhaps racy with other people spawning caching_threads.
So maybe better to stop all threads (including cleaner and committer)
and then free everything?
>
> - free_root_pointers(fs_info, 1);
> + btrfs_stop_all_workers(fs_info);
>
> del_fs_roots(fs_info);
>
> - iput(fs_info->btree_inode);
> + free_root_pointers(fs_info, 1);
>
> - btrfs_stop_all_workers(fs_info);
> + iput(fs_info->btree_inode);
>
> #ifdef CONFIG_BTRFS_FS_CHECK_INTEGRITY
> if (btrfs_test_opt(root, CHECK_INTEGRITY))
> --
> 1.7.7.6
>
> --
> To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at http://vger.kernel.org/majordomo-info.html
Alex.
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] Btrfs: stop all workers before cleaning up roots
2013-08-01 14:05 ` Alex Lyakas
@ 2013-08-05 15:09 ` Josef Bacik
0 siblings, 0 replies; 3+ messages in thread
From: Josef Bacik @ 2013-08-05 15:09 UTC (permalink / raw)
To: Alex Lyakas; +Cc: Josef Bacik, linux-btrfs
On Thu, Aug 01, 2013 at 05:05:35PM +0300, Alex Lyakas wrote:
> Hi Josef,
>
> On Thu, May 30, 2013 at 11:58 PM, Josef Bacik <jbacik@fusionio.com> wrote:
> > Dave reported a panic because the extent_root->commit_root was NULL in the
> > caching kthread. That is because we just unset it in free_root_pointers, which
> > is not the correct thing to do, we have to either wait for the caching kthread
> > to complete or hold the extent_commit_sem lock so we know the thread has exited.
> > This patch makes the kthreads all stop first and then we do our cleanup. This
> > should fix the race. Thanks,
> >
> > Reported-by: David Sterba <dsterba@suse.cz>
> > Signed-off-by: Josef Bacik <jbacik@fusionio.com>
> > ---
> > fs/btrfs/disk-io.c | 6 +++---
> > 1 files changed, 3 insertions(+), 3 deletions(-)
> >
> > diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
> > index 2b53afd..77cb566 100644
> > --- a/fs/btrfs/disk-io.c
> > +++ b/fs/btrfs/disk-io.c
> > @@ -3547,13 +3547,13 @@ int close_ctree(struct btrfs_root *root)
> >
> > btrfs_free_block_groups(fs_info);
>
> do you think it would be safer to stop all workers first and make sure
> they are stopped, then do btrfs_free_block_groups()? I see, for
> example, that btrfs_free_block_groups() checks:
> if (block_group->cached == BTRFS_CACHE_STARTED)
> which could be perhaps racy with other people spawning caching_threads.
>
> So maybe better to stop all threads (including cleaner and committer)
> and then free everything?
>
Well nobody should be writing anymore, so we shouldn't be starting any new
caching_kthreads, we should just be cleaning up threads that are already
running. Btrfs_free_block_groups() will wait on any kthreads it spawned, so we
are good there. Hth,
Josef
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2013-08-05 15:11 UTC | newest]
Thread overview: 3+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2013-05-30 20:58 [PATCH] Btrfs: stop all workers before cleaning up roots Josef Bacik
2013-08-01 14:05 ` Alex Lyakas
2013-08-05 15:09 ` Josef Bacik
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.