On Mon, Jan 15, 2018 at 1:58 PM, Miklos Szeredi <miklos@xxxxxxxxxx> wrote:
> On Thu, Jan 4, 2018 at 6:20 PM, Amir Goldstein <amir73il@xxxxxxxxx> wrote:
>> We only need to encode origin if there is a chance that the same object was
>> encoded pre copy up and then we need to stay consistent with the same
>> encoding also after copy up.
>>
>> In case a non-pure upper is not indexed, then it was copied up before NFS
>> export support was enabled. In that case, we don't need to worry about
>> staying consistent with pre copy up encoding and we encode an upper file
>> handle.
>>
>> This mitigates the problem that with no index, we cannot find an upper
>> inode from origin inode, so we cannot decode a non-indexed upper from
>> origin file handle.
>>
>> Signed-off-by: Amir Goldstein <amir73il@xxxxxxxxx>
>> ---
>> fs/overlayfs/export.c | 28 +++++++++++++++++++++++-----
>> 1 file changed, 23 insertions(+), 5 deletions(-)
>>
>> diff --git a/fs/overlayfs/export.c b/fs/overlayfs/export.c
>> index 48ae02f3acb8..919d43aaa387 100644
>> --- a/fs/overlayfs/export.c
>> +++ b/fs/overlayfs/export.c
>> @@ -19,6 +19,28 @@
>> #include <linux/ratelimit.h>
>> #include "overlayfs.h"
>>
>> +/*
>> + * We only need to encode origin if there is a chance that the same object was
>> + * encoded pre copy up and then we need to stay consistent with the same
>> + * encoding also after copy up. If non-pure upper is not indexed, then it was
>> + * copied up before NFS export was enabled. In that case we don't need to worry
>> + * about staying consistent with pre copy up encoding and we encode an upper
>> + * file handle.
>> + */
>> +static bool ovl_should_encode_origin(struct dentry *dentry)
>> +{
>> + /* Root dentry was born upper */
>> + if (dentry == dentry->d_sb->s_root)
>> + return false;
>
> Root can be lower, no (when there's no upper layer at all)? The
> comment is confusing at best.
>
Probably more than "just confusing" as I did not test NFS export
with no-upper overlayfs case.
At best encode will fail.
I will test this setup.
Thanks,
Amir.
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