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  1. 01 6月, 2018 6 次提交
    • A
      NFS: Pass "privileged" value to nfs4_init_sequence() · fba83f34
      由 Anna Schumaker 提交于 
      We currently have a separate function just to set this, but I think it
makes more sense to set it at the same time as the other values in
nfs4_init_sequence()
Signed-off-by: NAnna Schumaker <Anna.Schumaker@Netapp.com>
Signed-off-by: NTrond Myklebust <trond.myklebust@hammerspace.com>
      fba83f34
    • A
      NFS: Move call to nfs4_state_protect() to nfs4_commit_setup() · e9ae1ee2
      由 Anna Schumaker 提交于 
      Rather than doing this in the generic NFS client code.  Let's put this
with the other v4 stuff so it's all in one place.
Signed-off-by: NAnna Schumaker <Anna.Schumaker@Netapp.com>
Signed-off-by: NTrond Myklebust <trond.myklebust@hammerspace.com>
      e9ae1ee2
    • A
      NFS: Move call to nfs4_state_protect_write() to nfs4_write_setup() · fb91fb0e
      由 Anna Schumaker 提交于 
      This doesn't really need to be in the generic NFS client code, and I
think it makes more sense to keep the v4 code in one place.
Signed-off-by: NAnna Schumaker <Anna.Schumaker@Netapp.com>
Signed-off-by: NTrond Myklebust <trond.myklebust@hammerspace.com>
      fb91fb0e
    • N
      NFS: Avoid quadratic search when freeing delegations. · e04bbf6b
      由 NeilBrown 提交于 
      There are three places that walk all delegation for an nfs_client and
restart whenever they find something interesting - potentially
resulting in a quadratic search:  If there are 10,000 uninteresting
delegations followed by 10,000 interesting one, then the code
skips over 100,000,000 delegations, which can take a noticeable amount
of time.

Of these nfs_delegation_reap_unclaimed() and
nfs_reap_expired_delegations() are only called during unusual events:
a server reboots or reports expired delegations, probably due to a
network partition.  Optimizing these is not particularly important.

The third, nfs_client_return_marked_delegations(), is called
periodically via nfs_expire_unreferenced_delegations().  It could
cause periodic problems on a busy server.

New delegations are added to the end of the list, so if there are
10,000 open files with delegations, and 10,000 more recently opened files
that received delegations but are now closed, then
nfs_client_return_marked_delegations() can take seconds to skip over
the 10,000 open files 10,000 times.  That is a waste of time.

The avoid this waste a place-holder (an inode) is kept when locks are
dropped, so that the place can usually be found again after taking
rcu_readlock().  This place holder ensure that we find the right
starting point in the list of nfs_servers, and makes is probable that
we find the right starting point in the list of delegations.
We might need to occasionally restart at the head of that list.

It might be possible that the place_holder inode could lose its
delegation separately, and then get a new one using the same (freed
and then reallocated) 'struct nfs_delegation'.  Were this to happen,
the new delegation would be at the end of the list and we would miss
returning some other delegations.  This would have the effect of
unnecessarily delaying the return of some unused delegations until the
next time this function is called - typically 90 seconds later.  As
this is not a correctness issue and is vanishingly unlikely to happen,
it does not seem worth addressing.
Signed-off-by: NNeilBrown <neilb@suse.com>
Signed-off-by: NTrond Myklebust <trond.myklebust@hammerspace.com>
      e04bbf6b
    • N
      NFS: use cond_resched() when restarting walk of delegation list. · 3ca951b6
      由 NeilBrown 提交于 
      In three places we walk the list of delegations for an nfs_client
until an interesting one is found, then we act of that delegation
and restart the walk.

New delegations are added to the end of a list and the interesting
delegations are usually old, so in many case we won't repeat
a long walk over and over again, but it is possible - particularly if
the first server in the list has a large number of uninteresting
delegations.

In each cache the work done on interesting delegations will often
complete without sleeping, so this could loop many times without
giving up the CPU.

So add a cond_resched() at an appropriate point to avoid hogging the
CPU for too long.
Signed-off-by: NNeilBrown <neilb@suse.com>
Signed-off-by: NTrond Myklebust <trond.myklebust@hammerspace.com>
      3ca951b6
    • N
      NFS: slight optimization for walking list for delegations · f3893491
      由 NeilBrown 提交于 
      There are 3 places where we walk the list of delegations
for an nfs_client.
In each case there are two nested loops, one for nfs_servers
and one for nfs_delegations.

When we find an interesting delegation we try to get an active
reference to the server.  If that fails, it is pointless to
continue to look at the other delegation for the server as
we will never be able to get an active reference.
So instead of continuing in the inner loop, break out
and continue in the outer loop.
Signed-off-by: NNeilBrown <neilb@suse.com>
Signed-off-by: NTrond Myklebust <trond.myklebust@hammerspace.com>
      f3893491
  3. 29 5月, 2018 3 次提交
  5. 11 4月, 2018 28 次提交
  7. 06 4月, 2018 1 次提交
  9. 04 4月, 2018 1 次提交
    • D
      fscache: Attach the index key and aux data to the cookie · 402cb8dd
      由 David Howells 提交于 
      Attach copies of the index key and auxiliary data to the fscache cookie so
that:

 (1) The callbacks to the netfs for this stuff can be eliminated.  This
     can simplify things in the cache as the information is still
     available, even after the cache has relinquished the cookie.

 (2) Simplifies the locking requirements of accessing the information as we
     don't have to worry about the netfs object going away on us.

 (3) The cache can do lazy updating of the coherency information on disk.
     As long as the cache is flushed before reboot/poweroff, there's no
     need to update the coherency info on disk every time it changes.

 (4) Cookies can be hashed or put in a tree as the index key is easily
     available.  This allows:

     (a) Checks for duplicate cookies can be made at the top fscache layer
     	 rather than down in the bowels of the cache backend.

     (b) Caching can be added to a netfs object that has a cookie if the
     	 cache is brought online after the netfs object is allocated.

A certain amount of space is made in the cookie for inline copies of the
data, but if it won't fit there, extra memory will be allocated for it.

The downside of this is that live cache operation requires more memory.
Signed-off-by: NDavid Howells <dhowells@redhat.com>
Acked-by: NAnna Schumaker <anna.schumaker@netapp.com>
Tested-by: NSteve Dickson <steved@redhat.com>
      402cb8dd
  11. 28 3月, 2018 1 次提交