quota: unify quota init condition in setattr

Quota must being initialized if size or uid/git changes requested.
But initialization performed in two different places:
in case of i_size file system is responsible for dquot init
, but in case of uid/gid init will be called internally in
dquot_transfer().
This ambiguity makes code harder to understand.
Let's move this logic to one common helper function.

Signed-off-by: Dmitry Monakhov <dmonakhov@openvz.org>
Signed-off-by: Jan Kara <jack@suse.cz>

fs/jfs/file.c

@@ -98,7 +98,7 @@ int jfs_setattr(struct dentry *dentry, struct iattr *iattr)
 	if (rc)
 		return rc;
 
-	if (iattr->ia_valid & ATTR_SIZE)
+	if (is_quota_modification(inode, iattr))
 		dquot_initialize(inode);
 	if ((iattr->ia_valid & ATTR_UID && iattr->ia_uid != inode->i_uid) ||
 	    (iattr->ia_valid & ATTR_GID && iattr->ia_gid != inode->i_gid)) {