On Wed, May 16, 2018 at 2:18 PM, Miklos Szeredi <miklos@xxxxxxxxxx> wrote:
> 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.
>>>
>>
I guess it would be wise to leave that check in at least for the case we end
up using a cached inode instead of the new inode we created...
Thanks,
Amir.
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