| Message ID | 1396458780-10923-1-git-send-email-dsterba@suse.cz (mailing list archive) |
|---|---|
| State | Rejected |
| Headers | show |
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 -- 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
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 -- 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
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. -- 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
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 -- 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
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. -- 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
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; /*
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(-)