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From: Miklos Szeredi <miklos@szeredi.hu>
To: Amir Goldstein <amir73il@gmail.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>,
	Vivek Goyal <vgoyal@redhat.com>,
	overlayfs <linux-unionfs@vger.kernel.org>,
	linux-fsdevel <linux-fsdevel@vger.kernel.org>
Subject: Re: [PATCH v3 2/4] ovl: relax WARN_ON() real inode attributes mismatch
Date: Wed, 16 May 2018 13:18:35 +0200	[thread overview]
Message-ID: <CAJfpegvJN_CDHcGw7sXbAgE_a3r0V5hC70COMuv6Z6o4yef=NA@mail.gmail.com> (raw)
In-Reply-To: <CAOQ4uxiX3tNDV+aT1BFei4HReXybdTBgGQHGss1VOF5d0HX9VA@mail.gmail.com>

On Wed, May 16, 2018 at 1:06 PM, Amir Goldstein <amir73il@gmail.com> wrote:
> On Wed, May 16, 2018 at 1:29 PM, Miklos Szeredi <miklos@szeredi.hu> wrote:
>> On Tue, May 15, 2018 at 12:26 PM, Amir Goldstein <amir73il@gmail.com> wrote:
>>> Overlayfs should cope with online changes to underlying layer
>>> without crashing the kernel, which is what xfstest overlay/019
>>> checks.
>>>
>>> This test may sometimes trigger WARN_ON() in ovl_create_or_link()
>>> when linking an overlay inode that has been changed on underlying
>>> layer.
>>>
>>> Replace those WARN_ON() with pr_warn_ratelimited() to prevent
>>> test from failing and because this is more appropriate to the
>>> use case.
>>>
>>> Signed-off-by: Amir Goldstein <amir73il@gmail.com>
>>> ---
>>>  fs/overlayfs/dir.c | 14 +++++++++++---
>>>  1 file changed, 11 insertions(+), 3 deletions(-)
>>>
>>> diff --git a/fs/overlayfs/dir.c b/fs/overlayfs/dir.c
>>> index 62e6733b755c..25b339278684 100644
>>> --- a/fs/overlayfs/dir.c
>>> +++ b/fs/overlayfs/dir.c
>>> @@ -525,9 +525,17 @@ static int ovl_create_or_link(struct dentry *dentry, struct inode *inode,
>>>         if (!err) {
>>>                 struct inode *realinode = d_inode(ovl_dentry_upper(dentry));
>>>
>>> -               WARN_ON(inode->i_mode != realinode->i_mode);
>>> -               WARN_ON(!uid_eq(inode->i_uid, realinode->i_uid));
>>> -               WARN_ON(!gid_eq(inode->i_gid, realinode->i_gid));
>>> +               if (inode->i_mode != realinode->i_mode ||
>>> +                   !uid_eq(inode->i_uid, realinode->i_uid) ||
>>> +                   !gid_eq(inode->i_gid, realinode->i_gid)) {
>>> +                       pr_warn_ratelimited("overlayfs: real inode attributes mismatch (%pd2, %o.%u.%u != %o.%u.%u).\n",
>>> +                               dentry, inode->i_mode,
>>> +                               from_kuid(&init_user_ns, inode->i_uid),
>>> +                               from_kgid(&init_user_ns, inode->i_gid),
>>> +                               realinode->i_mode,
>>> +                               from_kuid(&init_user_ns, realinode->i_uid),
>>> +                               from_kgid(&init_user_ns, realinode->i_gid));
>>> +               }
>>
>> How about just dropping the warnings altogether.  They didn't discover
>> an issue with the code, just something normal, so IMO we should just
>> get rid of them.
>>
>
> OK. On that subject, do you want to leave the 'debug' argument
> to ovl_do_XXX? I started peeling it off slowly from the new helpers,
> but maybe we should just yank it completely from the ovl_do_XXX
> helpers? pr_debug can be disabled dynamically anyway. right?

Right.  The original idea was to not debug upper operations that are
just verbatim copies of the overlay operation, but I guess it doesn't
really hurt to debug unconditionally.

Thanks,
Miklos

  reply	other threads:[~2018-05-16 11:18 UTC|newest]

Thread overview: 27+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-05-15 10:26 [PATCH v3 0/4] Overlayfs mkdir related fixes Amir Goldstein
2018-05-15 10:26 ` [PATCH v3 1/4] ovl: use insert_inode_locked4() to hash a newly created inode Amir Goldstein
2018-05-15 13:23   ` Vivek Goyal
2018-05-15 13:37     ` Amir Goldstein
2018-05-16  8:34       ` Miklos Szeredi
2018-05-16  9:51         ` Amir Goldstein
2018-05-16 10:14           ` Miklos Szeredi
2018-05-16 11:03             ` Amir Goldstein
2018-05-17  6:03       ` Amir Goldstein
2018-05-17  8:10         ` Miklos Szeredi
2018-05-17  8:45           ` Amir Goldstein
2018-05-17  8:53           ` Miklos Szeredi
2018-05-17  8:58             ` Amir Goldstein
2018-05-17  9:07               ` Miklos Szeredi
2018-05-17 16:14                 ` Amir Goldstein
2018-05-15 10:26 ` [PATCH v3 2/4] ovl: relax WARN_ON() real inode attributes mismatch Amir Goldstein
2018-05-15 12:48   ` Vivek Goyal
2018-05-15 12:55     ` Amir Goldstein
2018-05-16 10:29   ` Miklos Szeredi
2018-05-16 11:06     ` Amir Goldstein
2018-05-16 11:18       ` Miklos Szeredi [this message]
2018-05-16 13:46         ` Amir Goldstein
2018-05-15 10:26 ` [PATCH v3 3/4] ovl: create helper ovl_create_temp() Amir Goldstein
2018-05-16 10:41   ` Miklos Szeredi
2018-05-16 11:15     ` Amir Goldstein
2018-05-16 11:37       ` Miklos Szeredi
2018-05-15 10:26 ` [PATCH v3 4/4] ovl: make ovl_create_real() cope with vfs_mkdir() safely Amir Goldstein

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