在 2021/6/7 21:51, Trond Myklebust 写道:
在 2021/6/2 1:36,trondmy@xxxxxxxxxx 写道:
From: Trond Myklebust<trond.myklebust@xxxxxxxxxxxxxxx>
If the inode is being evicted, but has to return a delegation
first,
then it can cause a deadlock in the corner case where the server
reboots
before the delegreturn completes, but while the call to
iget5_locked() in
nfs4_opendata_get_inode() is waiting for the inode free to
complete.
Since the open call still holds a session slot, the reboot recovery
cannot proceed.
In order to break the logjam, we can turn the delegation return
into a
privileged operation for the case where we're evicting the inode.
We
know that in that case, there can be no other state recovery
operation
that conflicts.
it's looks good to me.
but i have another confuse, how to ensure no writeback when evict nfs
inode?
because flush writes to server when close?
but not all close will flush writes to server.
The struct nfs_open_context holds a reference to the dentry (which
holds a reference to the inode) and to the superblock. The struct
nfs_page that is tracking page dirtiness then holds a reference to the
nfs_open_context.
That mechanism ensures the inode cannot be evicted until all dirty
pages have been either flushed or cancelled. The only thing we need to
worry about is the delegation and the pNFS layout since neither one is
allowed to reference the inode in any way (because otherwise they would
prevent the memory reclaim mechanisms from working).
Yes, it is.
Thank you very much.
