aufs: plink hlist 1/5, tiny, split au_plink_half_refresh()

extract a part of au_plink_half_refresh() and create a new function
au_plink_do_half_refresh(). The behaviour doesn't change.

This commit is a part of 'plink hlist' series which converts a simple
linked list intoa hashed array. See other commits too.

Signed-off-by: J. R. Okajima <hooanon05@yahoo.co.jp>
aufs: plink hlist 2/5, tiny, implement au_sphl for hlist

Implement au_sphl functions which are very similar to au_spl.
The behaviour doesn't change.

This commit is a part of 'plink hlist' series which converts a simple
linked list intoa hashed array. See other commits too.

Signed-off-by: J. R. Okajima <hooanon05@yahoo.co.jp>
aufs: plink hlist 3/5, convert the plink list into hlist

Simply convert it. This is a simple hlist. By suceeding commit, it will
be converted a hashed array.

This commit is a part of 'plink hlist' series which converts a simple
linked list intoa hashed array. See other commits too.

Signed-off-by: J. R. Okajima <hooanon05@yahoo.co.jp>
aufs: plink hlist 4/5, make it a hashed array

Make it a hashed array using struct au_sphl.
The number of hashing buckets is still defined as 100 (AuPlink_NHASH).
I don't know the most proper number, so it may be changed in the future.
When the number of objects in a single bucket reaches AUFS_PLINK_WARN, a
warning is produced.
By this commit, the meaning of AUFS_PLINK_WARN changes.

This commit is a part of 'plink hlist' series which converts a simple
linked list intoa hashed array. See other commits too.

Signed-off-by: J. R. Okajima <hooanon05@yahoo.co.jp>
aufs: plink hlist 5/5, implement /debug/aufs/si_<id>/plink

In order to see the status of the plink hlist, implement
/debug/aufs/si_<id>/plink. For the format, see
Documentation/ABI/testing/debugfs-aufs.

This commit is a part of 'plink hlist' series which converts a simple
linked list intoa hashed array. See other commits too.

Signed-off-by: J. R. Okajima <hooanon05@yahoo.co.jp>
Merge remote branch 'aufs3-standalone/aufs3.2/00base' into aufs3.2/10static
Merge branch 'aufs3.2/10static' into aufs3.2/11proc_map
Merge branch 'aufs3.2/11proc_map' into aufs3.2/18public
aufs: update the donator list

Signed-off-by: J. R. Okajima <hooanon05@yahoo.co.jp>
Merge remote branch 'aufs3-standalone/aufs3.2/00base' into aufs3.2/10static
Merge branch 'aufs3.2/10static' into aufs3.2/11proc_map
Merge branch 'aufs3.2/11proc_map' into aufs3.2/18public