2010-11-16 14:26:16

by Nick Piggin

[permalink] [raw]
Subject: [patch 21/28] fs: dcache reduce locking in d_alloc

Signed-off-by: Nick Piggin <[email protected]>

---
fs/dcache.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)

Index: linux-2.6/fs/dcache.c
===================================================================
--- linux-2.6.orig/fs/dcache.c 2010-11-17 00:52:37.000000000 +1100
+++ linux-2.6/fs/dcache.c 2010-11-17 01:05:39.000000000 +1100
@@ -1220,11 +1220,13 @@ struct dentry *d_alloc(struct dentry * p

if (parent) {
spin_lock(&parent->d_lock);
- spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED);
+ /*
+ * don't need child lock because it is not subject
+ * to concurrency here
+ */
dentry->d_parent = dget_dlock(parent);
dentry->d_sb = parent->d_sb;
list_add(&dentry->d_u.d_child, &parent->d_subdirs);
- spin_unlock(&dentry->d_lock);
spin_unlock(&parent->d_lock);
}