On Wed, May 16, 2018 at 1:06 PM, Amir Goldstein <amir73il@xxxxxxxxx> wrote:
> On Wed, May 16, 2018 at 1:29 PM, Miklos Szeredi <miklos@xxxxxxxxxx> wrote:
>> On Tue, May 15, 2018 at 12:26 PM, Amir Goldstein <amir73il@xxxxxxxxx> 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@xxxxxxxxx>
>>> ---
>>> 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
