fs: take dcache_lock inside __d_path

All callers take dcache_lock just around the call to __d_path, so
take the lock into it in preparation of getting rid of dcache_lock.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

fs/dcache.c

@@ -1994,7 +1994,7 @@ static int prepend_path(const struct path *path, struct path *root,
  * Returns a pointer into the buffer or an error code if the
  * path was too long.
  *
- * "buflen" should be positive. Caller holds the dcache_lock.
+ * "buflen" should be positive.
  *
  * If path is not reachable from the supplied root, then the value of
  * root is changed (without modifying refcounts).
@@ -2006,10 +2006,12 @@ char *__d_path(const struct path *path, struct path *root,
 	int error;
 
 	prepend(&res, &buflen, "\0", 1);
+	spin_lock(&dcache_lock);
 	error = prepend_path(path, root, &res, &buflen);
+	spin_unlock(&dcache_lock);
+
 	if (error)
 		return ERR_PTR(error);
-
 	return res;
 }
 

fs/seq_file.c

@@ -462,9 +462,7 @@ int seq_path_root(struct seq_file *m, struct path *path, struct path *root,
 	if (size) {
 		char *p;
 
-		spin_lock(&dcache_lock);
 		p = __d_path(path, root, buf, size);
-		spin_unlock(&dcache_lock);
 		res = PTR_ERR(p);
 		if (!IS_ERR(p)) {
 			char *end = mangle_path(buf, p, esc);

security/apparmor/path.c

@@ -72,10 +72,8 @@ static int d_namespace_path(struct path *path, char *buf, int buflen,
 		path_get(&root);
 	}
 
-	spin_lock(&dcache_lock);
 	tmp = root;
 	res = __d_path(path, &tmp, buf, buflen);
-	spin_unlock(&dcache_lock);
 
 	*name = res;
 	/* handle error conditions - and still allow a partial path to

security/tomoyo/realpath.c

@@ -127,10 +127,8 @@ char *tomoyo_realpath_from_path(struct path *path)
 		/* If we don't have a vfsmount, we can't calculate. */
 		if (!path->mnt)
 			break;
-		spin_lock(&dcache_lock);
 		/* go to whatever namespace root we are under */
 		pos = __d_path(path, &ns_root, buf, buf_len);
-		spin_unlock(&dcache_lock);
 		/* Prepend "/proc" prefix if using internal proc vfs mount. */
 		if (!IS_ERR(pos) && (path->mnt->mnt_flags & MNT_INTERNAL) &&
 		    (path->mnt->mnt_sb->s_magic == PROC_SUPER_MAGIC)) {