On 2017/9/11 21:34, Amir Goldstein Wrote:
> On Mon, Aug 7, 2017 at 10:57 AM, zhangyi (F) <yi.zhang@xxxxxxxxxx> wrote:
>> Hi,all:
>> I found two problemes about overlayfs, please let me know what you think:
>>
>> 1. Cannot update upper dir's access time.
>> Reproduce:
>> # mkdir lower upper worker merger
>> # mkdir upper/dir
>> # mount -t overlay -o lowerdir=lower,upperdir=upper,workdir=worker overlayfs merger
>> # ls mrger/dir
>> # stat mrger/dir
>> Access: 2017-08-07 11:03:56.364771584 -0400
>> Modify: 2017-08-07 11:01:52.319771584 -0400
>> Change: 2017-08-07 11:01:52.319771584 -0400
>> # touch mrger/dir/aa
>> # stat mrger/dir
>> Access: 2017-08-07 11:03:56.364771584 -0400
>> Modify: 2017-08-07 11:05:33.969771584 -0400
>> Change: 2017-08-07 11:05:33.969771584 -0400
>> # ls mrger/dir
>> # stat mrger/dir
>> Access: 2017-08-07 11:03:56.364771584 -0400
>> Modify: 2017-08-07 11:05:33.969771584 -0400
>> Change: 2017-08-07 11:05:33.969771584 -0400
>>
>> I find the reason of this problem is in update_ovl_inode_times():
>> (598e3c8f7 "vfs: update ovl inode before relatime check")
>>
>> static void update_ovl_inode_times(struct dentry *dentry, struct inode *inode,
>> bool rcu)
>> {
>> if (!rcu) {
>> struct inode *realinode = d_real_inode(dentry);
>>
>> *d_real_inode() cannot get dir's real inode, so i_mtime always equal to i_ctime*
>> *an not updated*
>>
>> if (unlikely(inode != realinode) &&
>> (!timespec_equal(&inode->i_mtime, &realinode->i_mtime) ||
>> !timespec_equal(&inode->i_ctime, &realinode->i_ctime))) {
>> inode->i_mtime = realinode->i_mtime;
>> inode->i_ctime = realinode->i_ctime;
>> }
>> }
>> }
>>
>> 2. Chattr will modify lower file's attributes directly.
>> Reproduce:
>> # mkdir lower upper worker merger
>> # touch lower/aa
>> # lsattr -p lower/aa
>> 0 --------------e---- lower/aa
>> # mount -t overlay -o lowerdir=lower,upperdir=upper,workdir=worker overlayfs merger
>> # chattr -p 123 merger/aa #set project id
>> # lsattr -p lower/aa
>> 123 --------------e---- lower/aa
>>
>> If we try to set "immutable" or any other attributes, the result are consistent.
>> Because chattr open file in RDONLY mode, so it will not trigger copyup, and then,
>> FS_IOC_SETFLAGS ioctl will get the lower inode and modify it. By the way,
>> ovl's directory not support ioctl now, so we fail to change dir's attributes.
>>
>> Do you think these two "problemes" need to fix or should avoid ?
>>
>
> ZhangYi,
>
> Now that fixes for the 2 issues you reported are in overlayfs-next,
> could you send those 2 reproducers as xfstests?
>
Yes, I saw the patches and looks good to me. I will send those two reproducers soon, thanks.
Thanks,
ZhangYi.
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