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path: root/fs/nfs/nfs4session.c
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2013-05-20NFSv4.1 Fix a pNFS session draining deadlockAndy Adamson
On a CB_RECALL the callback service thread flushes the inode using filemap_flush prior to scheduling the state manager thread to return the delegation. When pNFS is used and I/O has not yet gone to the data server servicing the inode, a LAYOUTGET can preceed the I/O. Unlike the async filemap_flush call, the LAYOUTGET must proceed to completion. If the state manager starts to recover data while the inode flush is sending the LAYOUTGET, a deadlock occurs as the callback service thread holds the single callback session slot until the flushing is done which blocks the state manager thread, and the state manager thread has set the session draining bit which puts the inode flush LAYOUTGET RPC to sleep on the forechannel slot table waitq. Separate the draining of the back channel from the draining of the fore channel by moving the NFS4_SESSION_DRAINING bit from session scope into the fore and back slot tables. Drain the back channel first allowing the LAYOUTGET call to proceed (and fail) so the callback service thread frees the callback slot. Then proceed with draining the forechannel. Signed-off-by: Andy Adamson <andros@netapp.com> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2012-12-15NFSv4.1: Deal effectively with interrupted RPC calls.Trond Myklebust
If an RPC call is interrupted, assume that the server hasn't processed the RPC call so that the next time we use the slot, we know that if we get a NFS4ERR_SEQ_MISORDERED or NFS4ERR_SEQ_FALSE_RETRY, we just have to bump the sequence number. Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2012-12-15NFSv4.1: Move the RPC timestamp out of the slot.Trond Myklebust
Shave a few bytes off the slot table size by moving the RPC timestamp into the sequence results. Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2012-12-11NFSv4.1: Be conservative about the client highest slotidTrond Myklebust
If the server sends us a target that looks like an outlier, but is lower than the existing target, then respect it anyway. However defer actually updating the generation counter until we get a target that doesn't look like an outlier. Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2012-12-06NFSv4.1: Try to eliminate outliers when updating target_highest_slotidTrond Myklebust
Look for sudden changes in the first and second derivatives in order to eliminate outlier changes to target_highest_slotid (which are due to out-of-order RPC replies). Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2012-12-06NFSv4.1: Ensure smooth handover of slots from one task to the next waitingTrond Myklebust
Currently, we see a lot of bouncing for the value of highest_used_slotid due to the fact that slots are getting freed, instead of getting instantly transmitted to the next waiting task. Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
2012-12-06NFSv4.1: Cleanup move session slot management to fs/nfs/nfs4session.cTrond Myklebust
NFSv4.1 session management is getting complex enough to deserve a separate file. Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>