On Thu, 19 Jun 2014 10:49:06 -0400
Jeff Layton <jlayton@xxxxxxxxxxxxxxx> wrote:
> Here it is. The long awaited removal of the client_mutex from knfsd.
> As many of us are aware, one of the major bottlenecks in NFSv4 serving
> is the fact that all compounds are processed while holding a single,
> global mutex.
>
> This has an obvious detrimental effect on scalability. I've heard
> anecdotal reports of 10x slowdowns with v4 serving vs. v3 on the same
> machine, primarily due to it.
>
> This patchset eliminates that mutex and (hopefully!) the bottleneck
> that it imposes. The basic idea is to add refcounting to most of the
> objects that compounds deal with to ensure that they are pinned while
> in use. Spinlocks are used to protect things like the hashtables and
> trees that track the objects.
>
> Benny started this set quite some time ago, and Trond took up the
> torch early this spring. He then handed it to me to clean up the
> remaining bits about a month ago.
>
> I'd like to see this considered for v3.17. Obviously, getting it into
> linux-next ASAP would be a good thing once it passes review.
>
> Some other highlights/notes:
>
> - use of lockdep has been greatly increased. I found it was the only
> way to ensure that I didn't create lock inversion problems and such.
>
> - clients are now only looked up once per compund and are cached in
> the cstate. This keeps us from having to keep searching for the
> same client for each compound op.
>
> - openowners and lockowners are now handled more sanely. References
> to them are only held by the stateids that are associated with them,
> and they are destroyed when the last reference to them is put. Also,
> lockowners can now have more than one stateid (in accordance with
> the spec)
>
> - the fault injection code has been overhauled. It should look the same
> to users, but it needed major work to deal with the new locking.
> It's probably possible to consolidate some of that code as well --
> it more cut-and-pastey than I'd like.
>
> - I've added a file to document how all of the moving parts fit
> together. It probably can use more fleshing out, but it's a start.
>
> - the lease handling is now a bit more complex than I'd like. Lease
> removal in particular is currently called under a spinlock, which
> I think we'll need to eventually clean up. For now, this is ok
> since the first thing that vfs_setlease does is lock the i_lock,
> but I think we'll eventually need to do an i_lock pushdown in the
> lease handling code, and ensure that vfs_setlease isn't called
> under a spinlock.
>
> As always, comments and review are welcome.
>
> Benny Halevy (1):
> nfsd4: use cl_lock to synchronize all stateid idr calls
>
> Jeff Layton (40):
> NFSd: Ensure that nfs4_file_get_access enforces share access modes
> locks: add file_has_lease
> NFSd: Protect the nfs4_file delegation fields using the fi_lock
> NFSd: Allow lockowners to hold several stateids
> NFSd: Ensure atomicity of stateid destruction and idr tree removal
> NFSd: Cleanup the freeing of stateids
> nfsd: do filp_close in sc_free callback for lock stateids
> NFSd: Add locking to protect the state owner lists
> nfsd: clean up races in lock stateid searching and creation
> nfsd: clean up lockowner refcounting when finding them
> nfsd: add an operation for unhashing a stateowner
> nfsd: clean up nfs4_release_lockowner
> nfsd: clean up refcounting for lockowners
> nfsd: declare v4.1+ openowners confirmed on creation
> nfsd: make openstateids hold references to their openowners
> nfsd: don't allow CLOSE to proceed until refcount on stateid drops
> lockdep: add lockdep_assert_not_held
> nfsd: add locking to stateowner release
> nfsd: optimize destroy_lockowner cl_lock thrashing
> nfsd: reduce cl_lock trashing in release_openowner
> NFSd: Protect session creation and client confirm using client_lock
> nfsd: protect the close_lru list and oo_last_closed_stid with
> client_lock
> nfsd: ensure that clp->cl_revoked list is protected by clp->cl_lock
> nfsd: move unhash_client_locked call into mark_client_expired_locked
> nfsd: fix misleading comment
> nfsd: don't destroy client if mark_client_expired_locked fails
> nfsd: don't destroy clients that are busy
> nfsd: abstract out the get and set routines into the fault injection
> ops
> nfsd: add a forget_clients "get" routine with proper locking
> nfsd: add a forget_client set_clnt routine
> nfsd: add nfsd_inject_forget_clients
> nfsd: add a list_head arg to nfsd_foreach_client_lock
> nfsd: add more granular locking to forget_locks fault injector
> nfsd: add more granular locking to forget_openowners fault injector
> nfsd: add more granular locking to *_delegations fault injectors
> nfsd: remove old fault injection infrastructure
> nfsd: remove nfs4_lock_state: nfs4_laundromat
> nfsd: remove nfs4_lock_state: nfs4_state_shutdown_net
> nfsd: remove the client_mutex and the nfs4_lock/unlock_state wrappers
> nfsd: add file documenting new state object model
>
> Trond Myklebust (63):
> nfsd: Protect addition to the file_hashtbl
> NFSd: Avoid taking state_lock while holding inode lock in
> nfsd_break_one_deleg
> NFSd: nfs4_preprocess_seqid_op should only set *stpp on success
> NFSd: Add fine grained protection for the nfs4_file->fi_stateids list
> NFSd: Add a mutex to protect the NFSv4.0 open owner replay cache
> NFSd: Add locking to the nfs4_file->fi_fds[] array
> NFSd: Lock owners are not per open stateid
> NFSd: Clean up helper __release_lock_stateid
> NFSd: NFSv4 lock-owners are not associated to a specific file
> NFSd: Cleanup nfs4svc_encode_compoundres
> NFSd: Don't get a session reference without a client reference
> NFSd: Allow struct nfsd4_compound_state to cache the nfs4_client
> NFSd: Move the delegation reference counter into the struct nfs4_stid
> NFSd: Simplify stateid management
> NFSd: Fix delegation revocation
> NFSd: Add reference counting to the lock and open stateids
> NFSd: clean up nfsd4_close_open_stateid
> NFSd: Add a struct nfs4_file field to struct nfs4_stid
> NFSd: Replace nfs4_ol_stateid->st_file with the st_stid.sc_file
> NFSd: Ensure stateids remain unique until they are freed
> NFSd: Convert delegation counter to an atomic_long_t type
> NFSd: Slight cleanup of find_stateid()
> NFSd: Add reference counting to find_stateid
> NFSd: Add reference counting to lock stateids
> NFSd: nfsd4_locku() must reference the lock stateid
> NFSd: Ensure that nfs4_open_delegation() references the delegation
> stateid
> NFSd: nfsd4_process_open2() must reference the delegation stateid
> NFSd: nfsd4_process_open2() must reference the open stateid
> NFSd: Prepare nfsd4_close() for open stateid referencing
> NFSd: nfsd4_open_confirm() must reference the open stateid
> NFSd: Add reference counting to nfs4_preprocess_confirmed_seqid_op
> NFSd: Migrate the stateid reference into nfs4_preprocess_seqid_op
> NFSd: Migrate the stateid reference into nfs4_lookup_stateid()
> NFSd: Migrate the stateid reference into nfs4_find_stateid_by_type()
> NFSd: Add reference counting to state owners
> NFSd: Keep a reference to the open stateid for the NFSv4.0 replay
> cache
> NFSd: Make lock stateid take a reference to the lockowner
> NFSd: Protect adding/removing open state owners using client_lock
> NFSd: Protect adding/removing lock owners using client_lock
> NFSd: Cleanup - Let nfsd4_lookup_stateid() take a cstate argument
> NFSd: Cache the client that was looked up in lookup_clientid()
> NFSd: Convert nfsd4_process_open1() to work with lookup_clientid()
> NFSd: Always use lookup_clientid() in nfsd4_process_open1
> NFSd: Move the open owner hash table into struct nfs4_client
> NFSd: Convert nfs4_check_open_reclaim() to work with lookup_clientid()
> NFSd: Ensure struct nfs4_client is unhashed before we try to destroy
> it
> NFSd: Ensure that the laundromat unhashes the client before releasing
> locks
> NFSd: Don't require client_lock in free_client
> NFSd: Move create_client() call outside the lock
> NFSd: Protect unconfirmed client creation using client_lock
> NFSd: Protect nfsd4_destroy_clientid using client_lock
> NFSd: Ensure lookup_clientid() takes client_lock
> NFSd: Add assertions to document the nfs4_client/session locking
> NFSd: Remove nfs4_lock_state(): nfs4_preprocess_stateid_op()
> NFSd: Remove nfs4_lock_state(): nfsd4_test_stateid/nfsd4_free_stateid
> NFSd: Remove nfs4_lock_state(): nfsd4_release_lockowner
> NFSd: Remove nfs4_lock_state(): nfsd4_lock/locku/lockt()
> NFSd: Remove nfs4_lock_state(): nfsd4_open_downgrade + nfsd4_close
> NFSd: Remove nfs4_lock_state(): nfsd4_delegreturn()
> NFSd: Remove nfs4_lock_state(): nfsd4_open and nfsd4_open_confirm
> NFSd: Remove nfs4_lock_state(): exchange_id, create/destroy_session()
> NFSd: Remove nfs4_lock_state(): setclientid, setclientid_confirm,
> renew
> NFSd: Remove nfs4_lock_state(): reclaim_complete()
>
> .../filesystems/nfs/nfsd4-state-objects.txt | 110 +
> fs/locks.c | 26 +
> fs/nfsd/fault_inject.c | 129 +-
> fs/nfsd/netns.h | 5 -
> fs/nfsd/nfs4callback.c | 18 +-
> fs/nfsd/nfs4proc.c | 16 +-
> fs/nfsd/nfs4state.c | 2569 ++++++++++++++------
> fs/nfsd/nfs4xdr.c | 17 +-
> fs/nfsd/state.h | 86 +-
> fs/nfsd/xdr4.h | 8 +-
> include/linux/fs.h | 6 +
> include/linux/lockdep.h | 6 +
> 12 files changed, 2052 insertions(+), 944 deletions(-)
> create mode 100644 Documentation/filesystems/nfs/nfsd4-state-objects.txt
>
Oh, I should also mention that this set is also available in my
nfsd-devel branch at:
git://git.samba.org/jlayton/linux.git
I'll continue to push changes to the set to that branch as review comes
in.
Thanks!
--
Jeff Layton <jlayton@xxxxxxxxxxxxxxx>
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