Re: [PATCH RFC v8 0/2] nfsd: Initial implementation of NFSv4 Courteous Server

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> On Dec 13, 2021, at 12:24 PM, Dai Ngo <dai.ngo@xxxxxxxxxx> wrote:
> 
> 
> Hi Bruce,
> 
> This series of patches implement the NFSv4 Courteous Server.
> 
> A server which does not immediately expunge the state on lease expiration
> is known as a Courteous Server.  A Courteous Server continues to recognize
> previously generated state tokens as valid until conflict arises between
> the expired state and the requests from another client, or the server
> reboots.
> 
> The v2 patch includes the following:
> 
> . add new callback, lm_expire_lock, to lock_manager_operations to
>  allow the lock manager to take appropriate action with conflict lock.
> 
> . handle conflicts of NFSv4 locks with NFSv3/NLM and local locks.
> 
> . expire courtesy client after 24hr if client has not reconnected.
> 
> . do not allow expired client to become courtesy client if there are
>  waiters for client's locks.
> 
> . modify client_info_show to show courtesy client and seconds from
>  last renew.
> 
> . fix a problem with NFSv4.1 server where the it keeps returning
>  SEQ4_STATUS_CB_PATH_DOWN in the successful SEQUENCE reply, after
>  the courtesy client re-connects, causing the client to keep sending
>  BCTS requests to server.
> 
> The v3 patch includes the following:
> 
> . modified posix_test_lock to check and resolve conflict locks
>  to handle NLM TEST and NFSv4 LOCKT requests.
> 
> . separate out fix for back channel stuck in SEQ4_STATUS_CB_PATH_DOWN.
> 
> The v4 patch includes:
> 
> . rework nfsd_check_courtesy to avoid dead lock of fl_lock and client_lock
>  by asking the laudromat thread to destroy the courtesy client.
> 
> . handle NFSv4 share reservation conflicts with courtesy client. This
>  includes conflicts between access mode and deny mode and vice versa.
> 
> . drop the patch for back channel stuck in SEQ4_STATUS_CB_PATH_DOWN.
> 
> The v5 patch includes:
> 
> . fix recursive locking of file_rwsem from posix_lock_file. 
> 
> . retest with LOCKDEP enabled.
> 
> The v6 patch includes:
> 
> . merge witn 5.15-rc7
> 
> . fix a bug in nfs4_check_deny_bmap that did not check for matched
>  nfs4_file before checking for access/deny conflict. This bug causes
>  pynfs OPEN18 to fail since the server taking too long to release
>  lots of un-conflict clients' state.
> 
> . enhance share reservation conflict handler to handle case where
>  a large number of conflict courtesy clients need to be expired.
>  The 1st 100 clients are expired synchronously and the rest are
>  expired in the background by the laundromat and NFS4ERR_DELAY
>  is returned to the NFS client. This is needed to prevent the
>  NFS client from timing out waiting got the reply.
> 
> The v7 patch includes:
> 
> . Fix race condition in posix_test_lock and posix_lock_inode after
>  dropping spinlock.
> 
> . Enhance nfsd4_fl_expire_lock to work with with new lm_expire_lock
>  callback
> 
> . Always resolve share reservation conflicts asynchrously.
> 
> . Fix bug in nfs4_laundromat where spinlock is not used when
>  scanning cl_ownerstr_hashtbl.
> 
> . Fix bug in nfs4_laundromat where idr_get_next was called
>  with incorrect 'id'. 
> 
> . Merge nfs4_destroy_courtesy_client into nfsd4_fl_expire_lock.
> 
> The v8 patch includes:
> 
> . Fix warning in nfsd4_fl_expire_lock reported by test robot.

These patches are also available in the nfsd-courteous-server topic
branch of git://git.kernel.org/pub/scm/linux/kernel/git/cel/linux.git.


--
Chuck Lever







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