Get the value of an extended attribute on an object.
@param io the context in which the attribute is read
@param o name of the object
@param name which extended attribute to read
@param buf where to store the result
@param len size of buf in bytes
@returns length of xattr value on success, negative error code on failure
Get the value of an extended attribute on an object.
@param io the context in which the attribute is read @param o name of the object @param name which extended attribute to read @param buf where to store the result @param len size of buf in bytes @returns length of xattr value on success, negative error code on failure