From 4ef2a4f43f5e52c6ff50a53cb49cf468bacf8cc2 Mon Sep 17 00:00:00 2001 From: Lars Ellenberg Date: Thu, 20 Dec 2018 17:23:33 +0100 Subject: drbd: fix confusing error message during attach If we attach a (consistent) backing device, which knows about a last-agreed effective size, and that effective size is *larger* than the currently requested size, we refused to attach with ERR_DISK_TOO_SMALL Failure: (111) Low.dev. smaller than requested DRBD-dev. size. which is confusing to say the least. This patch changes the error code in that case to ERR_IMPLICIT_SHRINK Failure: (170) Implicit device shrinking not allowed. See kernel log. additional info from kernel: To-be-attached device has last effective > current size, and is consistent (9999 > 7777 sectors). Refusing to attach. It also allows to attach with an explicit size. Signed-off-by: Lars Ellenberg Signed-off-by: Jens Axboe --- drivers/block/drbd/drbd_nl.c | 49 +++++++++++++++++++++++++++++++++++++++----- 1 file changed, 44 insertions(+), 5 deletions(-) diff --git a/drivers/block/drbd/drbd_nl.c b/drivers/block/drbd/drbd_nl.c index d02d38fd1288..e4774f720de5 100644 --- a/drivers/block/drbd/drbd_nl.c +++ b/drivers/block/drbd/drbd_nl.c @@ -127,6 +127,35 @@ static int drbd_msg_put_info(struct sk_buff *skb, const char *info) return 0; } +__printf(2, 3) +static int drbd_msg_sprintf_info(struct sk_buff *skb, const char *fmt, ...) +{ + va_list args; + struct nlattr *nla, *txt; + int err = -EMSGSIZE; + int len; + + nla = nla_nest_start(skb, DRBD_NLA_CFG_REPLY); + if (!nla) + return err; + + txt = nla_reserve(skb, T_info_text, 256); + if (!txt) { + nla_nest_cancel(skb, nla); + return err; + } + va_start(args, fmt); + len = vscnprintf(nla_data(txt), 256, fmt, args); + va_end(args); + + /* maybe: retry with larger reserve, if truncated */ + txt->nla_len = nla_attr_size(len+1); + nlmsg_trim(skb, (char*)txt + NLA_ALIGN(txt->nla_len)); + nla_nest_end(skb, nla); + + return 0; +} + /* This would be a good candidate for a "pre_doit" hook, * and per-family private info->pointers. * But we need to stay compatible with older kernels. @@ -1947,11 +1976,21 @@ int drbd_adm_attach(struct sk_buff *skb, struct genl_info *info) } /* Prevent shrinking of consistent devices ! */ - if (drbd_md_test_flag(nbc, MDF_CONSISTENT) && - drbd_new_dev_size(device, nbc, nbc->disk_conf->disk_size, 0) < nbc->md.la_size_sect) { - drbd_warn(device, "refusing to truncate a consistent device\n"); - retcode = ERR_DISK_TOO_SMALL; - goto force_diskless_dec; + { + unsigned long long nsz = drbd_new_dev_size(device, nbc, nbc->disk_conf->disk_size, 0); + unsigned long long eff = nbc->md.la_size_sect; + if (drbd_md_test_flag(nbc, MDF_CONSISTENT) && nsz < eff) { + if (nsz == nbc->disk_conf->disk_size) { + drbd_warn(device, "truncating a consistent device during attach (%llu < %llu)\n", nsz, eff); + } else { + drbd_warn(device, "refusing to truncate a consistent device (%llu < %llu)\n", nsz, eff); + drbd_msg_sprintf_info(adm_ctx.reply_skb, + "To-be-attached device has last effective > current size, and is consistent\n" + "(%llu > %llu sectors). Refusing to attach.", eff, nsz); + retcode = ERR_IMPLICIT_SHRINK; + goto force_diskless_dec; + } + } } lock_all_resources(); -- cgit v1.2.1