the inode semaphore

Adding fh_put() to release the semaphore after nfsd_unlink() within nfs3proc.c does make the hang disappear. Hope we can see this get fixed in the future code.

wendy
----- Original Message -----
From: Wendy Cheng
To: [email protected]
Sent: Tuesday, February 11, 2003 12:17 PM
Subject: the inode semaphore

We're working on a high availability experiment project for our linux-based server and the nfsds hang from times to times. It is observed that the version 3 procedure 12/13 (rmdir and remove) obtains an inode semaphore within fh_lock()/nfsd_unlink() but never releases it. Theoretically this inode is going to get released but what can prevent the following two cases that would end up hanging the nfsd ?

1. Due to slow network and/or system, the client re- sends the same request but using a different xid. The nfsd that accepts the new request would be stuck in nfsd_unlink() waiting for the inode semaphore.
2. A "create" immediately follows the "remove" for the same file.

There is a flag called fh_locked but it is passed in from each individual nfs request (a local copy, not from dcache) that doesn't help. I also browse thru some file system's (say ext3) inode free code but can't find anywhere this semaphore gets released. We're still debugging our failover logic but if someone could confirm the above are indeed a bug (or explain why it will not happen) would be of great helps.

Or should this semaphore get "zero"ed out by file system (say, ext3) ?

We're on 2.4.19 kernel.

Thanks for the help.

Wendy