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SubjectRe: [PATCH RFC v3] vfs: make fstatat retry once on ESTALE errors from getattr call
Chuck Lever <> writes:

> On Apr 23, 2012, at 10:51 AM, Miklos Szeredi wrote:
>> "J. Bruce Fields" <> writes:
>>> I also wonder whether it would be making too many assumptions about the
>>> server or filesystem: just because ordinary posix interfaces don't allow
>>> atomic replacement of a whole directory tree doesn't mean the server
>>> might not have some way to do it.
>> Exactly because posix limits the atomic replacement to empty directories
>> is that this feature is not useful and is why linux can get away with
>> the dead directory behavior in this case. And thinking about fixing
>> this in NFS is completely pointless since no one will rely on the atomic
>> replacement behavior. Fixing local filesystems is also pointless for
>> the same reason.
>> Atomic replacement of whole directory trees would indeed be more useful,
>> but it's highly unlikely to be used anywhere since applications relying
>> on this feature would be limited to special filesystems that allow this.
> The cases I can think of have to do with file system restore, file
> system and block device snapshots, and so on. This type of use case
> may not practical on today's Linux server, but they are a reality for
> anyone using high-end NFS storage.

Problem with this is: if some directory file handles are stale (e.g. due
to directories being removed, recreated, moved around) and on the client
there are cwd-s referring to these handles, then they are going to
become stale no matter what you do, even if the same path does exist
after the restore on the server.


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