> On Sep 15, 2021, at 04:03, zhangxiaoxu (A) <zhangxiaoxu5@xxxxxxxxxx> wrote:
>
> Hi Trond,
>
> I have some confuse about 'nfs_sb_active'.
>
> The following commit increase the 'sb->s_active' to prevent concurrent with umount process when handle the callback rpc message.
>
> e39d8a186ed0 ("NFSv4: Fix an Oops during delegation callbacks")
> 113aac6d567b ("NFS: nfs_delegation_find_inode_server must first reference the superblock")
>
> But it also delay the process in function 'generic_shutdown_super', such as 'sync_filesystem' and 'fsnotify_sb_delete'.
>
> For the common file system, when umount success, the data should be stable to the disk, but in nfs, it maybe delay?
>
> I want know :
> 1. whether we _must_ stable the data to the server?
> 2. how to ensure the data not lost when umount success but client crash?
> 3. the delayed fsnotify umount event is reasonable or not?
> 4. the 'nfs_sb_active' should be used under what scenario?
>
> Thanks.
That has nothing to do with I/O. Delegations are state.
_________________________________
Trond Myklebust
Linux NFS client maintainer, Hammerspace
trond.myklebust@xxxxxxxxxxxxxxx
