fs: dcache scale hash

Add a new lock, dcache_hash_lock, to protect the dcache hash table from
concurrent modification. d_hash is also protected by d_lock.

Signed-off-by: Nick Piggin <npiggin@kernel.dk>

1 files changed, 2 insertions, 33 deletions

diff --git a/include/linux/dcache.h b/include/linux/dcache.h
index cea27dfca532..2feb624b67f1 100644
--- a/include/linux/dcache.h
+++ b/include/linux/dcache.h
@@ -184,39 +184,6 @@ struct dentry_operations {
 extern spinlock_t dcache_lock;
 extern seqlock_t rename_lock;
 
-/**
- * d_drop - drop a dentry
- * @dentry: dentry to drop
- *
- * d_drop() unhashes the entry from the parent dentry hashes, so that it won't
- * be found through a VFS lookup any more. Note that this is different from
- * deleting the dentry - d_delete will try to mark the dentry negative if
- * possible, giving a successful _negative_ lookup, while d_drop will
- * just make the cache lookup fail.
- *
- * d_drop() is used mainly for stuff that wants to invalidate a dentry for some
- * reason (NFS timeouts or autofs deletes).
- *
- * __d_drop requires dentry->d_lock.
- */
-
-static inline void __d_drop(struct dentry *dentry)
-{
-        if (!(dentry->d_flags & DCACHE_UNHASHED)) {
-                dentry->d_flags |= DCACHE_UNHASHED;
-                hlist_del_rcu(&dentry->d_hash);
-        }
-}
-
-static inline void d_drop(struct dentry *dentry)
-{
-        spin_lock(&dcache_lock);
-        spin_lock(&dentry->d_lock);
-        __d_drop(dentry);
-        spin_unlock(&dentry->d_lock);
-        spin_unlock(&dcache_lock);
-}
-
 static inline int dname_external(struct dentry *dentry)
 {
         return dentry->d_name.name != dentry->d_iname;
@@ -228,6 +195,8 @@ static inline int dname_external(struct dentry *dentry)
 extern void d_instantiate(struct dentry *, struct inode *);
 extern struct dentry * d_instantiate_unique(struct dentry *, struct inode *);
 extern struct dentry * d_materialise_unique(struct dentry *, struct inode *);
+extern void __d_drop(struct dentry *dentry);
+extern void d_drop(struct dentry *dentry);
 extern void d_delete(struct dentry *);
 
 /* allocate/de-allocate */