* [PATCH] btrfs: fix reversed warning condition in btrfs_delayed_inode_reserve_metadata
@ 2014-04-02 17:13 David Sterba
2014-04-03 1:49 ` Liu Bo
2014-04-03 5:34 ` Liu Bo
0 siblings, 2 replies; 6+ messages in thread
From: David Sterba @ 2014-04-02 17:13 UTC (permalink / raw)
To: linux-btrfs; +Cc: David Sterba, Dulshani Gunawardhana, stable
Commit fae7f21cece9a4c181 ("btrfs: Use WARN_ON()'s return value in place of
WARN_ON(1)") cleaned up WARN_ON usage and in one place reversed the condition
that led to loads of warnings that were not supposed to occur.
WARN_ON will trigger because it sees 'ret' though in the previous code
did not reach the WARN_ON below. The correct pattern is
- if (condition)
+ if (WARN_ON(condition))
CC: Dulshani Gunawardhana <dulshani.gunawardhana89@gmail.com>
CC: <stable@vger.kernel.org> # 3.13
Reported-by: Liu Bo <bo.li.liu@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.cz>
---
fs/btrfs/delayed-inode.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/fs/btrfs/delayed-inode.c b/fs/btrfs/delayed-inode.c
index 451b00c86f6c..098af20abd88 100644
--- a/fs/btrfs/delayed-inode.c
+++ b/fs/btrfs/delayed-inode.c
@@ -649,7 +649,7 @@ static int btrfs_delayed_inode_reserve_metadata(
goto out;
ret = btrfs_block_rsv_migrate(src_rsv, dst_rsv, num_bytes);
- if (!WARN_ON(ret))
+ if (WARN_ON(!ret))
goto out;
/*
--
1.9.0
^ permalink raw reply related [flat|nested] 6+ messages in thread
* Re: [PATCH] btrfs: fix reversed warning condition in btrfs_delayed_inode_reserve_metadata
2014-04-02 17:13 [PATCH] btrfs: fix reversed warning condition in btrfs_delayed_inode_reserve_metadata David Sterba
@ 2014-04-03 1:49 ` Liu Bo
2014-04-03 5:34 ` Liu Bo
1 sibling, 0 replies; 6+ messages in thread
From: Liu Bo @ 2014-04-03 1:49 UTC (permalink / raw)
To: David Sterba; +Cc: linux-btrfs, Dulshani Gunawardhana, stable
On Wed, Apr 02, 2014 at 07:13:00PM +0200, David Sterba wrote:
> Commit fae7f21cece9a4c181 ("btrfs: Use WARN_ON()'s return value in place of
> WARN_ON(1)") cleaned up WARN_ON usage and in one place reversed the condition
> that led to loads of warnings that were not supposed to occur.
>
> WARN_ON will trigger because it sees 'ret' though in the previous code
> did not reach the WARN_ON below. The correct pattern is
>
> - if (condition)
> + if (WARN_ON(condition))
>
Reviewed-by: Liu Bo <bo.li.liu@oracle.com>
> CC: Dulshani Gunawardhana <dulshani.gunawardhana89@gmail.com>
> CC: <stable@vger.kernel.org> # 3.13
> Reported-by: Liu Bo <bo.li.liu@oracle.com>
> Signed-off-by: David Sterba <dsterba@suse.cz>
> ---
> fs/btrfs/delayed-inode.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/fs/btrfs/delayed-inode.c b/fs/btrfs/delayed-inode.c
> index 451b00c86f6c..098af20abd88 100644
> --- a/fs/btrfs/delayed-inode.c
> +++ b/fs/btrfs/delayed-inode.c
> @@ -649,7 +649,7 @@ static int btrfs_delayed_inode_reserve_metadata(
> goto out;
>
> ret = btrfs_block_rsv_migrate(src_rsv, dst_rsv, num_bytes);
> - if (!WARN_ON(ret))
> + if (WARN_ON(!ret))
> goto out;
>
> /*
> --
> 1.9.0
>
> --
> 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
-liubo
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] btrfs: fix reversed warning condition in btrfs_delayed_inode_reserve_metadata
2014-04-02 17:13 [PATCH] btrfs: fix reversed warning condition in btrfs_delayed_inode_reserve_metadata David Sterba
2014-04-03 1:49 ` Liu Bo
@ 2014-04-03 5:34 ` Liu Bo
2014-04-03 16:18 ` David Sterba
1 sibling, 1 reply; 6+ messages in thread
From: Liu Bo @ 2014-04-03 5:34 UTC (permalink / raw)
To: David Sterba; +Cc: linux-btrfs, Dulshani Gunawardhana, stable
On Wed, Apr 02, 2014 at 07:13:00PM +0200, David Sterba wrote:
> Commit fae7f21cece9a4c181 ("btrfs: Use WARN_ON()'s return value in place of
> WARN_ON(1)") cleaned up WARN_ON usage and in one place reversed the condition
> that led to loads of warnings that were not supposed to occur.
>
> WARN_ON will trigger because it sees 'ret' though in the previous code
> did not reach the WARN_ON below. The correct pattern is
>
> - if (condition)
> + if (WARN_ON(condition))
>
> CC: Dulshani Gunawardhana <dulshani.gunawardhana89@gmail.com>
> CC: <stable@vger.kernel.org> # 3.13
> Reported-by: Liu Bo <bo.li.liu@oracle.com>
> Signed-off-by: David Sterba <dsterba@suse.cz>
> ---
> fs/btrfs/delayed-inode.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/fs/btrfs/delayed-inode.c b/fs/btrfs/delayed-inode.c
> index 451b00c86f6c..098af20abd88 100644
> --- a/fs/btrfs/delayed-inode.c
> +++ b/fs/btrfs/delayed-inode.c
> @@ -649,7 +649,7 @@ static int btrfs_delayed_inode_reserve_metadata(
> goto out;
>
> ret = btrfs_block_rsv_migrate(src_rsv, dst_rsv, num_bytes);
> - if (!WARN_ON(ret))
> + if (WARN_ON(!ret))
> goto out;
Oh sorry, I'd have to get my Reviewed-by back and give a NACK instead.
With this patch, (ret = 0) triggers the WARNING, which is not right.
-liubo
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] btrfs: fix reversed warning condition in btrfs_delayed_inode_reserve_metadata
2014-04-03 5:34 ` Liu Bo
@ 2014-04-03 16:18 ` David Sterba
2014-04-04 3:03 ` Liu Bo
0 siblings, 1 reply; 6+ messages in thread
From: David Sterba @ 2014-04-03 16:18 UTC (permalink / raw)
To: Liu Bo; +Cc: linux-btrfs, Dulshani Gunawardhana, stable
On Thu, Apr 03, 2014 at 01:34:23PM +0800, Liu Bo wrote:
> On Wed, Apr 02, 2014 at 07:13:00PM +0200, David Sterba wrote:
> > Commit fae7f21cece9a4c181 ("btrfs: Use WARN_ON()'s return value in place of
> > WARN_ON(1)") cleaned up WARN_ON usage and in one place reversed the condition
> > that led to loads of warnings that were not supposed to occur.
> >
> > WARN_ON will trigger because it sees 'ret' though in the previous code
> > did not reach the WARN_ON below. The correct pattern is
> >
> > - if (condition)
> > + if (WARN_ON(condition))
> >
> > CC: Dulshani Gunawardhana <dulshani.gunawardhana89@gmail.com>
> > CC: <stable@vger.kernel.org> # 3.13
> > Reported-by: Liu Bo <bo.li.liu@oracle.com>
> > Signed-off-by: David Sterba <dsterba@suse.cz>
> > ---
> > fs/btrfs/delayed-inode.c | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/fs/btrfs/delayed-inode.c b/fs/btrfs/delayed-inode.c
> > index 451b00c86f6c..098af20abd88 100644
> > --- a/fs/btrfs/delayed-inode.c
> > +++ b/fs/btrfs/delayed-inode.c
> > @@ -649,7 +649,7 @@ static int btrfs_delayed_inode_reserve_metadata(
> > goto out;
> >
> > ret = btrfs_block_rsv_migrate(src_rsv, dst_rsv, num_bytes);
> > - if (!WARN_ON(ret))
> > + if (WARN_ON(!ret))
> > goto out;
>
> Oh sorry, I'd have to get my Reviewed-by back and give a NACK instead.
>
> With this patch, (ret = 0) triggers the WARNING, which is not right.
Thanks for catching this, you're right, my patch was wrong. I must say
the patch (fae7f21ce) made the code harder to read at some places, I
don't see much help in removing plain WARN_ON(1) at this cost.
Back to the warning flood you observed, the comment under the warning
says:
655 /*
656 * Ok this is a problem, let's just steal from the global rsv
657 * since this really shouldn't happen that often.
658 */
659 ret = btrfs_block_rsv_migrate(&root->fs_info->global_block_rsv,
660 dst_rsv, num_bytes);
so the question is why it does happen so often.
A WARN_ON_ONCE hides the severity of the problem, so I'd rather suggest
to put it under enospc_debug option so we can debug it and it does not
bother users. As this is closer to the way you were going to fix that,
I'm not sending a patch, take this as a review comment.
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] btrfs: fix reversed warning condition in btrfs_delayed_inode_reserve_metadata
2014-04-03 16:18 ` David Sterba
@ 2014-04-04 3:03 ` Liu Bo
2014-04-04 13:40 ` David Sterba
0 siblings, 1 reply; 6+ messages in thread
From: Liu Bo @ 2014-04-04 3:03 UTC (permalink / raw)
To: dsterba, linux-btrfs, Dulshani Gunawardhana, stable
On Thu, Apr 03, 2014 at 06:18:40PM +0200, David Sterba wrote:
> On Thu, Apr 03, 2014 at 01:34:23PM +0800, Liu Bo wrote:
> > On Wed, Apr 02, 2014 at 07:13:00PM +0200, David Sterba wrote:
> > > Commit fae7f21cece9a4c181 ("btrfs: Use WARN_ON()'s return value in place of
> > > WARN_ON(1)") cleaned up WARN_ON usage and in one place reversed the condition
> > > that led to loads of warnings that were not supposed to occur.
> > >
> > > WARN_ON will trigger because it sees 'ret' though in the previous code
> > > did not reach the WARN_ON below. The correct pattern is
> > >
> > > - if (condition)
> > > + if (WARN_ON(condition))
> > >
> > > CC: Dulshani Gunawardhana <dulshani.gunawardhana89@gmail.com>
> > > CC: <stable@vger.kernel.org> # 3.13
> > > Reported-by: Liu Bo <bo.li.liu@oracle.com>
> > > Signed-off-by: David Sterba <dsterba@suse.cz>
> > > ---
> > > fs/btrfs/delayed-inode.c | 2 +-
> > > 1 file changed, 1 insertion(+), 1 deletion(-)
> > >
> > > diff --git a/fs/btrfs/delayed-inode.c b/fs/btrfs/delayed-inode.c
> > > index 451b00c86f6c..098af20abd88 100644
> > > --- a/fs/btrfs/delayed-inode.c
> > > +++ b/fs/btrfs/delayed-inode.c
> > > @@ -649,7 +649,7 @@ static int btrfs_delayed_inode_reserve_metadata(
> > > goto out;
> > >
> > > ret = btrfs_block_rsv_migrate(src_rsv, dst_rsv, num_bytes);
> > > - if (!WARN_ON(ret))
> > > + if (WARN_ON(!ret))
> > > goto out;
> >
> > Oh sorry, I'd have to get my Reviewed-by back and give a NACK instead.
> >
> > With this patch, (ret = 0) triggers the WARNING, which is not right.
>
> Thanks for catching this, you're right, my patch was wrong. I must say
> the patch (fae7f21ce) made the code harder to read at some places, I
> don't see much help in removing plain WARN_ON(1) at this cost.
I agree, I prefer the original code which is easier to understand,
if (!ret)
goto out;
WARN_ON(1);
>
> Back to the warning flood you observed, the comment under the warning
> says:
>
> 655 /*
> 656 * Ok this is a problem, let's just steal from the global rsv
> 657 * since this really shouldn't happen that often.
> 658 */
> 659 ret = btrfs_block_rsv_migrate(&root->fs_info->global_block_rsv,
> 660 dst_rsv, num_bytes);
>
> so the question is why it does happen so often.
>
> A WARN_ON_ONCE hides the severity of the problem, so I'd rather suggest
> to put it under enospc_debug option so we can debug it and it does not
> bother users. As this is closer to the way you were going to fix that,
> I'm not sending a patch, take this as a review comment.
The comment was based on some assumptions which could be wrong according to
my observation.
-liubo
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] btrfs: fix reversed warning condition in btrfs_delayed_inode_reserve_metadata
2014-04-04 3:03 ` Liu Bo
@ 2014-04-04 13:40 ` David Sterba
0 siblings, 0 replies; 6+ messages in thread
From: David Sterba @ 2014-04-04 13:40 UTC (permalink / raw)
To: Liu Bo; +Cc: dsterba, linux-btrfs, Dulshani Gunawardhana, stable
On Fri, Apr 04, 2014 at 11:03:16AM +0800, Liu Bo wrote:
> On Thu, Apr 03, 2014 at 06:18:40PM +0200, David Sterba wrote:
> > On Thu, Apr 03, 2014 at 01:34:23PM +0800, Liu Bo wrote:
> > > On Wed, Apr 02, 2014 at 07:13:00PM +0200, David Sterba wrote:
> > > > Commit fae7f21cece9a4c181 ("btrfs: Use WARN_ON()'s return value in place of
> > > > WARN_ON(1)") cleaned up WARN_ON usage and in one place reversed the condition
> > > > that led to loads of warnings that were not supposed to occur.
> > > >
> > > > WARN_ON will trigger because it sees 'ret' though in the previous code
> > > > did not reach the WARN_ON below. The correct pattern is
> > > >
> > > > - if (condition)
> > > > + if (WARN_ON(condition))
> > > >
> > > > CC: Dulshani Gunawardhana <dulshani.gunawardhana89@gmail.com>
> > > > CC: <stable@vger.kernel.org> # 3.13
> > > > Reported-by: Liu Bo <bo.li.liu@oracle.com>
> > > > Signed-off-by: David Sterba <dsterba@suse.cz>
> > > > ---
> > > > fs/btrfs/delayed-inode.c | 2 +-
> > > > 1 file changed, 1 insertion(+), 1 deletion(-)
> > > >
> > > > diff --git a/fs/btrfs/delayed-inode.c b/fs/btrfs/delayed-inode.c
> > > > index 451b00c86f6c..098af20abd88 100644
> > > > --- a/fs/btrfs/delayed-inode.c
> > > > +++ b/fs/btrfs/delayed-inode.c
> > > > @@ -649,7 +649,7 @@ static int btrfs_delayed_inode_reserve_metadata(
> > > > goto out;
> > > >
> > > > ret = btrfs_block_rsv_migrate(src_rsv, dst_rsv, num_bytes);
> > > > - if (!WARN_ON(ret))
> > > > + if (WARN_ON(!ret))
> > > > goto out;
> > >
> > > Oh sorry, I'd have to get my Reviewed-by back and give a NACK instead.
> > >
> > > With this patch, (ret = 0) triggers the WARNING, which is not right.
> >
> > Thanks for catching this, you're right, my patch was wrong. I must say
> > the patch (fae7f21ce) made the code harder to read at some places, I
> > don't see much help in removing plain WARN_ON(1) at this cost.
>
> I agree, I prefer the original code which is easier to understand,
>
> if (!ret)
> goto out;
> WARN_ON(1);
>
> >
> > Back to the warning flood you observed, the comment under the warning
> > says:
> >
> > 655 /*
> > 656 * Ok this is a problem, let's just steal from the global rsv
> > 657 * since this really shouldn't happen that often.
> > 658 */
> > 659 ret = btrfs_block_rsv_migrate(&root->fs_info->global_block_rsv,
> > 660 dst_rsv, num_bytes);
> >
> > so the question is why it does happen so often.
> >
> > A WARN_ON_ONCE hides the severity of the problem, so I'd rather suggest
> > to put it under enospc_debug option so we can debug it and it does not
> > bother users. As this is closer to the way you were going to fix that,
> > I'm not sending a patch, take this as a review comment.
>
> The comment was based on some assumptions which could be wrong according to
> my observation.
Then the question is if the WARN_ON points to a problem or not.
^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2014-04-04 13:40 UTC | newest]
Thread overview: 6+ messages (download: mbox.gz follow: Atom feed
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2014-04-02 17:13 [PATCH] btrfs: fix reversed warning condition in btrfs_delayed_inode_reserve_metadata David Sterba
2014-04-03 1:49 ` Liu Bo
2014-04-03 5:34 ` Liu Bo
2014-04-03 16:18 ` David Sterba
2014-04-04 3:03 ` Liu Bo
2014-04-04 13:40 ` David Sterba
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