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  1. 07 1月, 2011 6 次提交
    • N
      fs: icache RCU free inodes · fa0d7e3d
      由 Nick Piggin 提交于 
      RCU free the struct inode. This will allow:

- Subsequent store-free path walking patch. The inode must be consulted for
  permissions when walking, so an RCU inode reference is a must.
- sb_inode_list_lock to be moved inside i_lock because sb list walkers who want
  to take i_lock no longer need to take sb_inode_list_lock to walk the list in
  the first place. This will simplify and optimize locking.
- Could remove some nested trylock loops in dcache code
- Could potentially simplify things a bit in VM land. Do not need to take the
  page lock to follow page->mapping.

The downsides of this is the performance cost of using RCU. In a simple
creat/unlink microbenchmark, performance drops by about 10% due to inability to
reuse cache-hot slab objects. As iterations increase and RCU freeing starts
kicking over, this increases to about 20%.

In cases where inode lifetimes are longer (ie. many inodes may be allocated
during the average life span of a single inode), a lot of this cache reuse is
not applicable, so the regression caused by this patch is smaller.

The cache-hot regression could largely be avoided by using SLAB_DESTROY_BY_RCU,
however this adds some complexity to list walking and store-free path walking,
so I prefer to implement this at a later date, if it is shown to be a win in
real situations. I haven't found a regression in any non-micro benchmark so I
doubt it will be a problem.
Signed-off-by: NNick Piggin <npiggin@kernel.dk>
      fa0d7e3d
    • N
      fs: dcache remove dcache_lock · b5c84bf6
      由 Nick Piggin 提交于 
      dcache_lock no longer protects anything. remove it.
Signed-off-by: NNick Piggin <npiggin@kernel.dk>
      b5c84bf6
    • N
      fs: Use rename lock and RCU for multi-step operations · 949854d0
      由 Nick Piggin 提交于 
      The remaining usages for dcache_lock is to allow atomic, multi-step read-side
operations over the directory tree by excluding modifications to the tree.
Also, to walk in the leaf->root direction in the tree where we don't have
a natural d_lock ordering.

This could be accomplished by taking every d_lock, but this would mean a
huge number of locks and actually gets very tricky.

Solve this instead by using the rename seqlock for multi-step read-side
operations, retry in case of a rename so we don't walk up the wrong parent.
Concurrent dentry insertions are not serialised against.  Concurrent deletes
are tricky when walking up the directory: our parent might have been deleted
when dropping locks so also need to check and retry for that.

We can also use the rename lock in cases where livelock is a worry (and it
is introduced in subsequent patch).
Signed-off-by: NNick Piggin <npiggin@kernel.dk>
      949854d0
    • N
      fs: scale inode alias list · b23fb0a6
      由 Nick Piggin 提交于 
      Add a new lock, dcache_inode_lock, to protect the inode's i_dentry list
from concurrent modification. d_alias is also protected by d_lock.
Signed-off-by: NNick Piggin <npiggin@kernel.dk>
      b23fb0a6
    • N
      fs: dcache scale dentry refcount · b7ab39f6
      由 Nick Piggin 提交于 
      Make d_count non-atomic and protect it with d_lock. This allows us to ensure a
0 refcount dentry remains 0 without dcache_lock. It is also fairly natural when
we start protecting many other dentry members with d_lock.
Signed-off-by: NNick Piggin <npiggin@kernel.dk>
      b7ab39f6
    • N
      fs: change d_delete semantics · fe15ce44
      由 Nick Piggin 提交于 
      Change d_delete from a dentry deletion notification to a dentry caching
advise, more like ->drop_inode. Require it to be constant and idempotent,
and not take d_lock. This is how all existing filesystems use the callback
anyway.

This makes fine grained dentry locking of dput and dentry lru scanning
much simpler.
Signed-off-by: NNick Piggin <npiggin@kernel.dk>
      fe15ce44
  3. 11 12月, 2010 1 次提交
  5. 08 12月, 2010 6 次提交
  7. 02 12月, 2010 1 次提交
    • T
      NFS: Fix a memory leak in nfs_readdir · 11de3b11
      由 Trond Myklebust 提交于 
      We need to ensure that the entries in the nfs_cache_array get cleared
when the page is removed from the page cache. To do so, we use the
freepage address_space operation.

Change nfs_readdir_clear_array to use kmap_atomic(), so that the
function can be safely called from all contexts.

Finally, modify the cache_page_release helper to call
nfs_readdir_clear_array directly, when dealing with an anonymous
page from 'uncached_readdir'.
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com>
      11de3b11
  9. 01 12月, 2010 2 次提交
  11. 23 11月, 2010 9 次提交
  13. 18 11月, 2010 1 次提交
  15. 17 11月, 2010 1 次提交
  17. 16 11月, 2010 4 次提交
  19. 31 10月, 2010 2 次提交
  21. 29 10月, 2010 3 次提交
  23. 28 10月, 2010 4 次提交