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authorDavid Howells <dhowells@redhat.com>2006-03-25 03:06:36 -0800
committerLinus Torvalds <torvalds@g5.osdl.org>2006-03-25 08:22:49 -0800
commit214fda1f6e1b8ef2a5292b0372744037fc80d318 (patch)
tree4cf0a18632cc663fcd75a1e23e357ec39c0c3b37
parent7d99b7d634d81bb372e03e4561c80430aa4cfac2 (diff)
downloadop-kernel-dev-214fda1f6e1b8ef2a5292b0372744037fc80d318.zip
op-kernel-dev-214fda1f6e1b8ef2a5292b0372744037fc80d318.tar.gz
[PATCH] Optimise d_find_alias()
The attached patch optimises d_find_alias() to only take the spinlock if there's anything in the the inode's alias list. If there isn't, it returns NULL immediately. With respect to the superblock sharing patch, this should reduce by one the number of times the dcache_lock is taken by nfs_lookup() for ordinary directory lookups. Only in the case where there's already a dentry for particular directory inode (such as might happen when another mountpoint is rooted at that dentry) will the lock then be taken the extra time. Signed-off-by: David Howells <dhowells@redhat.com> Cc: Trond Myklebust <trond.myklebust@fys.uio.no> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
-rw-r--r--fs/dcache.c11
1 files changed, 7 insertions, 4 deletions
diff --git a/fs/dcache.c b/fs/dcache.c
index 653f64c..139e5fd 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -325,10 +325,13 @@ static struct dentry * __d_find_alias(struct inode *inode, int want_discon)
struct dentry * d_find_alias(struct inode *inode)
{
- struct dentry *de;
- spin_lock(&dcache_lock);
- de = __d_find_alias(inode, 0);
- spin_unlock(&dcache_lock);
+ struct dentry *de = NULL;
+
+ if (!list_empty(&inode->i_dentry)) {
+ spin_lock(&dcache_lock);
+ de = __d_find_alias(inode, 0);
+ spin_unlock(&dcache_lock);
+ }
return de;
}
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