gfs2: Switch to generic xattr handlers

Switch to the generic xattr handlers and take the necessary glocks at
the layer below. The following are the new xattr "entry points"; they
are called with the glock held already in the following cases:

  gfs2_xattr_get: From SELinux, during lookups.
  gfs2_xattr_set: The glock is never held.
  gfs2_get_acl: From gfs2_create_inode -> posix_acl_create and
                gfs2_setattr -> posix_acl_chmod.
  gfs2_set_acl: From gfs2_setattr -> posix_acl_chmod.

Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 40 insertions, 6 deletions

diff --git a/fs/gfs2/xattr.c b/fs/gfs2/xattr.c
index 619886ba6e78..f42ab53bd30d 100644
--- a/fs/gfs2/xattr.c
+++ b/fs/gfs2/xattr.c
@@ -583,13 +583,11 @@ out:
  *
  * Returns: actual size of data on success, -errno on error
  */
-static int gfs2_xattr_get(const struct xattr_handler *handler,
-			  struct dentry *unused, struct inode *inode,
-			  const char *name, void *buffer, size_t size)
+static int __gfs2_xattr_get(struct inode *inode, const char *name,
+			    void *buffer, size_t size, int type)
 {
 	struct gfs2_inode *ip = GFS2_I(inode);
 	struct gfs2_ea_location el;
-	int type = handler->flags;
 	int error;
 
 	if (!ip->i_eattr)
@@ -611,6 +609,29 @@ static int gfs2_xattr_get(const struct xattr_handler *handler,
 	return error;
 }
 
+static int gfs2_xattr_get(const struct xattr_handler *handler,
+			  struct dentry *unused, struct inode *inode,
+			  const char *name, void *buffer, size_t size)
+{
+	struct gfs2_inode *ip = GFS2_I(inode);
+	struct gfs2_holder gh;
+	bool need_unlock = false;
+	int ret;
+
+	/* During lookup, SELinux calls this function with the glock locked. */
+
+	if (!gfs2_glock_is_locked_by_me(ip->i_gl)) {
+		ret = gfs2_glock_nq_init(ip->i_gl, LM_ST_SHARED, LM_FLAG_ANY, &gh);
+		if (ret)
+			return ret;
+		need_unlock = true;
+	}
+	ret = __gfs2_xattr_get(inode, name, buffer, size, handler->flags);
+	if (need_unlock)
+		gfs2_glock_dq_uninit(&gh);
+	return ret;
+}
+
 /**
  * ea_alloc_blk - allocates a new block for extended attributes.
  * @ip: A pointer to the inode that's getting extended attributes
@@ -1233,8 +1254,21 @@ static int gfs2_xattr_set(const struct xattr_handler *handler,
 			  struct dentry *dentry, const char *name,
 			  const void *value, size_t size, int flags)
 {
-	return __gfs2_xattr_set(d_inode(dentry), name, value,
-				size, flags, handler->flags);
+	struct inode *inode = d_inode(dentry);
+	struct gfs2_inode *ip = GFS2_I(inode);
+	struct gfs2_holder gh;
+	int ret;
+
+	ret = gfs2_rsqa_alloc(ip);
+	if (ret)
+		return ret;
+
+	ret = gfs2_glock_nq_init(ip->i_gl, LM_ST_EXCLUSIVE, 0, &gh);
+	if (ret)
+		return ret;
+	ret = __gfs2_xattr_set(inode, name, value, size, flags, handler->flags);
+	gfs2_glock_dq_uninit(&gh);
+	return ret;
 }
 
 static int ea_dealloc_indirect(struct gfs2_inode *ip)