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VFS: add lookup hint for network file systems 

I'm trying to speeding up mkdir(2) for network file systems.  A typical
mkdir(2) calls two inode_operations: lookup and mkdir.  The lookup
operation would fail with ENOENT in common case.  I think it is unnecessary
because the subsequent mkdir operation can check it.  In case of creat(2),
lookup operation is called with the LOOKUP_CREATE flag, so individual
filesystem can omit real lookup.  e.g.  nfs_lookup().

Here is a sample patch which uses LOOKUP_CREATE and O_EXCL on mkdir,
symlink and mknod.  This uses the gadget for creat(2).

And here is the result of a benchmark on NFSv3.
  mkdir(2) 10,000 times:
    original  50.5 sec
    patched   29.0 sec

Signed-off-by: ASANO Masahiro <masano@tnes.nec.co.jp>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
(cherry picked from fab7bf44449b29f9d5572a5dd8adcf7c91d5bf0f commit)
This commit is contained in:
ASANO Masahiro 2006-08-22 20:06:02 -04:00 committed by Trond Myklebust
parent ddeff520f0
commit a634904a7d
1 changed files with 2 additions and 0 deletions
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2
fs/namei.c
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@ -1767,6 +1767,8 @@ struct dentry *lookup_create(struct nameidata *nd, int is_dir)
if (nd->last_type != LAST_NORM)
goto fail;
nd->flags &= ~LOOKUP_PARENT;
nd->flags |= LOOKUP_CREATE;
nd->intent.open.flags = O_EXCL;
/*
* Do the final lookup.