/**
* Copy an extended attribute into the buffer provided, or compute
* the required buffer size if \a buf is NULL.
*
* On success, the number of bytes used or required is stored in \a sizep.
*
* Note that no locking is done here.
*
* \param[in] env execution environment
* \param[in] obj object for which to retrieve xattr
* \param[out] buf buffer to store xattr value in
* \param[in] name name of xattr to copy
* \param[out] sizep bytes used or required to store xattr
*
* \retval 0 on success
* \retval negative negated errno on failure
*/
int __osd_xattr_get(const struct lu_env *env, struct osd_object *obj,
struct lu_buf *buf, const char *name, int *sizep)
{
int rc;
/* check SA_ZPL_DXATTR first then fallback to directory xattr */
rc = __osd_sa_xattr_get(env, obj, buf, name, sizep);
if (rc != -ENOENT)
return rc;
return __osd_xattr_get_large(env, osd_obj2dev(obj), obj->oo_xattr,
buf, name, sizep);
}
int __osd_xattr_get(const struct lu_env *env, struct osd_object *obj,
struct lu_buf *buf, const char *name, int *sizep)
{
struct osd_device *osd = osd_obj2dev(obj);
udmu_objset_t *uos = &osd->od_objset;
uint64_t xa_data_obj;
dmu_buf_t *xa_data_db;
sa_handle_t *sa_hdl = NULL;
uint64_t size;
int rc;
/* check SA_ZPL_DXATTR first then fallback to directory xattr */
rc = __osd_sa_xattr_get(env, obj, buf, name, sizep);
if (rc != -ENOENT)
return rc;
/* are there any extended attributes? */
if (obj->oo_xattr == ZFS_NO_OBJECT)
return -ENOENT;
/* Lookup the object number containing the xattr data */
rc = -zap_lookup(uos->os, obj->oo_xattr, name, sizeof(uint64_t), 1,
&xa_data_obj);
if (rc)
return rc;
rc = __osd_obj2dbuf(env, uos->os, xa_data_obj, &xa_data_db, FTAG);
if (rc)
return rc;
rc = -sa_handle_get(uos->os, xa_data_obj, NULL, SA_HDL_PRIVATE,
&sa_hdl);
if (rc)
goto out_rele;
/* Get the xattr value length / object size */
rc = -sa_lookup(sa_hdl, SA_ZPL_SIZE(uos), &size, 8);
if (rc)
goto out;
if (size > INT_MAX) {
rc = -EOVERFLOW;
goto out;
}
*sizep = (int)size;
if (buf == NULL || buf->lb_buf == NULL) {
/* We only need to return the required size */
goto out;
}
if (*sizep > buf->lb_len) {
rc = -ERANGE; /* match ldiskfs error */
goto out;
}
rc = -dmu_read(uos->os, xa_data_db->db_object, 0,
size, buf->lb_buf, DMU_READ_PREFETCH);
out:
sa_handle_destroy(sa_hdl);
out_rele:
dmu_buf_rele(xa_data_db, FTAG);
return rc;
}
