stale or not stale
Subsystems (2)
It seems that nfsd can return reply attributes with a link count of zero but without an NFS3ERR_STALE status. We've seen this actually happen for a write request to a file with a single link that is concurrently being removed without NLM lock protection. What is the proper behavior here?
----- Original Message -----
Quoted 11 lines
From: "Ed Goggin" <[email protected]>
To: [email protected]
Sent: Thursday, August 2, 2012 9:57:58 PM
Subject: stale or not staleIt seems that nfsd can return reply attributes with a link count of zero but without an
NFS3ERR_STALEstatus. We've seen this actually happen for a write request to a file with a single link that is concurrently being removed without NLM lock protection. What is the proper behavior here?
I think it would be worthwhile to add here that the the remove was not concurrent with the write, and at the time of the NFS write a new file with the same name existed, yet fh decoding picked up the old inode instead of reporting -ESTALE. FS was ext4.
In fact seen two things happen - n_link = 0 and n_link = 1, and in both cases we knew the file was unlink()ed and re-creat()ed.
A
Quoted 13 lines · On Thu, 2 Aug 2012 19:29:14 -0700 (PDT) Andrei Warkentin…
----- Original Message -----
Quoted 11 lines
From: "Ed Goggin" <[email protected]>
To: [email protected]
Sent: Thursday, August 2, 2012 9:57:58 PM
Subject: stale or not staleIt seems that nfsd can return reply attributes with a link count of zero but without an
NFS3ERR_STALEstatus. We've seen this actually happen for a write request to a file with a single link that is concurrently being removed without NLM lock protection. What is the proper behavior here?
Quoted 4 lines
I think it would be worthwhile to add here that the the remove was not concurrent with the write, and at the time of the NFS write a new file with the same name existed, yet fh decoding picked up the old inode instead of reporting
-ESTALE. FS was ext4.In fact seen two things happen -
n_link= 0 andn_link= 1, and in both cases we knew the file was unlink()ed and re-creat()ed.
That's entirely valid behavior.
ESTALE from the server is its way of saying: "I don't recognize that filehandle". It can't figure out how to match that filehandle to an inode.
An i_nlink count of 0 means that there are no more hardlinks attached to the inode. It's deleted from the namespace, but the inode still exists until there are no more i_count references held on it.
Signature · 1 line
Jeff Layton <[email protected]>