[PATCH] dcache: Add helper d_hash_and_lookup
It is very common to hash a dentry and then to call lookup. If we take fs
specific hash functions into account the full hash logic can get ugly.
Further full_name_hash as an inline function is almost 100 bytes on x86 so
having a non-inline choice in some cases can measurably decrease code size.
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/fs/dcache.c b/fs/dcache.c
index 21dffee..940d188 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -1101,6 +1101,32 @@
}
/**
+ * d_hash_and_lookup - hash the qstr then search for a dentry
+ * @dir: Directory to search in
+ * @name: qstr of name we wish to find
+ *
+ * On hash failure or on lookup failure NULL is returned.
+ */
+struct dentry *d_hash_and_lookup(struct dentry *dir, struct qstr *name)
+{
+ struct dentry *dentry = NULL;
+
+ /*
+ * Check for a fs-specific hash function. Note that we must
+ * calculate the standard hash first, as the d_op->d_hash()
+ * routine may choose to leave the hash value unchanged.
+ */
+ name->hash = full_name_hash(name->name, name->len);
+ if (dir->d_op && dir->d_op->d_hash) {
+ if (dir->d_op->d_hash(dir, name) < 0)
+ goto out;
+ }
+ dentry = d_lookup(dir, name);
+out:
+ return dentry;
+}
+
+/**
* d_validate - verify dentry provided from insecure source
* @dentry: The dentry alleged to be valid child of @dparent
* @dparent: The parent dentry (known to be valid)
@@ -1616,26 +1642,12 @@
struct dentry * dentry;
ino_t ino = 0;
- /*
- * Check for a fs-specific hash function. Note that we must
- * calculate the standard hash first, as the d_op->d_hash()
- * routine may choose to leave the hash value unchanged.
- */
- name->hash = full_name_hash(name->name, name->len);
- if (dir->d_op && dir->d_op->d_hash)
- {
- if (dir->d_op->d_hash(dir, name) != 0)
- goto out;
- }
-
- dentry = d_lookup(dir, name);
- if (dentry)
- {
+ dentry = d_hash_and_lookup(dir, name);
+ if (dentry) {
if (dentry->d_inode)
ino = dentry->d_inode->i_ino;
dput(dentry);
}
-out:
return ino;
}