From: Eli Rosenthal Date: Thu, 9 Jun 2016 19:07:01 +0000 (-0700) Subject: OpenZFS 6738 - zfs send stream padding needs documentation X-Git-Tag: zfs-0.7.0-rc1~109^2~6 X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=f8866f8ae3ad987e8ef4a68ea0066639b5f69bcd;p=zfs OpenZFS 6738 - zfs send stream padding needs documentation Authored by: Eli Rosenthal Reviewed by: Matthew Ahrens Reviewed by: Dan Kimmel Reviewed by: Paul Dagnelie Reviewed by: Dan McDonald Approved by: Robert Mustacchi Ported-by: Brian Behlendorf OpenZFS-issue: https://www.illumos.org/issues/6738 OpenZFS-commit: https://github.com/openzfs/openzfs/commit/c20404ff --- diff --git a/module/zfs/dmu_send.c b/module/zfs/dmu_send.c index 1c7b53269..2f4087a67 100644 --- a/module/zfs/dmu_send.c +++ b/module/zfs/dmu_send.c @@ -107,6 +107,19 @@ dump_bytes_cb(void *arg) dmu_sendarg_t *dsp = dbi->dbi_dsp; dsl_dataset_t *ds = dmu_objset_ds(dsp->dsa_os); ssize_t resid; /* have to get resid to get detailed errno */ + + /* + * The code does not rely on this (len being a multiple of 8). We keep + * this assertion because of the corresponding assertion in + * receive_read(). Keeping this assertion ensures that we do not + * inadvertently break backwards compatibility (causing the assertion + * in receive_read() to trigger on old software). + * + * Removing the assertions could be rolled into a new feature that uses + * data that isn't 8-byte aligned; if the assertions were removed, a + * feature flag would have to be added. + */ + ASSERT0(dbi->dbi_len % 8); dsp->dsa_err = vn_rdwr(UIO_WRITE, dsp->dsa_vp, @@ -1806,7 +1819,10 @@ receive_read(struct receive_arg *ra, int len, void *buf) { int done = 0; - /* some things will require 8-byte alignment, so everything must */ + /* + * The code doesn't rely on this (lengths being multiples of 8). See + * comment in dump_bytes. + */ ASSERT0(len % 8); while (done < len) {