Re: [RFC] atomic create+open

[Miklos Szeredi]

> The reason why we do it as a lookup intent is because this has to be
> atomic lookup+create+open in order to be at all useful to NFS.
> 
> Just doing create+open atomically is worthless since it leaves you with
> a bunch of races where someone on the server can create, say, a symlink
> between the RPC call to lookup and the RPC call that creates the file.

That's easy to solve: filesystem returns -EAGAIN, namei_open() redoes
the lookup and continues with the resolving.  There would have to be
some safeguard counter to avoid infinite loops.

Filesystem could even populate the dentry with the symlink in
->open_create() to optimize away the relookup.

Do you see a problem with that?

Miklos
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