From 71932efc1cfccfe1cc8e48b21f8cea5fbbc80e24 Mon Sep 17 00:00:00 2001 From: Lars Ellenberg Date: Mon, 18 Apr 2011 09:43:25 +0200 Subject: [PATCH] drbd: allow status dump request all volumes of a specific resource We had drbd_adm_get_status (one single volume), and drbd_adm_get_status_all (dump of all volumes of all resources). This enhances the latter to be able to dump all volumes of just one specific resource. Signed-off-by: Philipp Reisner Signed-off-by: Lars Ellenberg --- drivers/block/drbd/drbd_nl.c | 70 +++++++++++++++++++++++++++++++++--- 1 file changed, 66 insertions(+), 4 deletions(-) diff --git a/drivers/block/drbd/drbd_nl.c b/drivers/block/drbd/drbd_nl.c index f86e882efcac..fff11ae79f15 100644 --- a/drivers/block/drbd/drbd_nl.c +++ b/drivers/block/drbd/drbd_nl.c @@ -2598,7 +2598,7 @@ out: return 0; } -int drbd_adm_get_status_all(struct sk_buff *skb, struct netlink_callback *cb) +int get_one_status(struct sk_buff *skb, struct netlink_callback *cb) { struct drbd_conf *mdev; struct drbd_genlmsghdr *dh; @@ -2616,6 +2616,9 @@ int drbd_adm_get_status_all(struct sk_buff *skb, struct netlink_callback *cb) * where tconn is cb->args[0]; * and i is cb->args[1]; * + * cb->args[2] indicates if we shall loop over all resources, + * or just dump all volumes of a single resource. + * * This may miss entries inserted after this dump started, * or entries deleted before they are reached. * @@ -2626,7 +2629,6 @@ int drbd_adm_get_status_all(struct sk_buff *skb, struct netlink_callback *cb) /* synchronize with drbd_new_tconn/drbd_free_tconn */ down_read(&drbd_cfg_rwsem); -next_tconn: /* revalidate iterator position */ list_for_each_entry(tmp, &drbd_tconns, all_tconn) { if (pos == NULL) { @@ -2641,16 +2643,22 @@ next_tconn: } } if (tconn) { +next_tconn: mdev = idr_get_next(&tconn->volumes, &volume); if (!mdev) { /* No more volumes to dump on this tconn. * Advance tconn iterator. */ pos = list_entry(tconn->all_tconn.next, struct drbd_tconn, all_tconn); - /* But, did we dump any volume on this tconn yet? */ + /* Did we dump any volume on this tconn yet? */ if (volume != 0) { - tconn = NULL; + /* If we reached the end of the list, + * or only a single resource dump was requested, + * we are done. */ + if (&pos->all_tconn == &drbd_tconns || cb->args[2]) + goto out; volume = 0; + tconn = pos; goto next_tconn; } } @@ -2696,6 +2704,60 @@ out: return skb->len; } +/* + * Request status of all resources, or of all volumes within a single resource. + * + * This is a dump, as the answer may not fit in a single reply skb otherwise. + * Which means we cannot use the family->attrbuf or other such members, because + * dump is NOT protected by the genl_lock(). During dump, we only have access + * to the incoming skb, and need to opencode "parsing" of the nlattr payload. + * + * Once things are setup properly, we call into get_one_status(). + */ +int drbd_adm_get_status_all(struct sk_buff *skb, struct netlink_callback *cb) +{ + const unsigned hdrlen = GENL_HDRLEN + GENL_MAGIC_FAMILY_HDRSZ; + struct nlattr *nla; + const char *conn_name; + struct drbd_tconn *tconn; + + /* Is this a followup call? */ + if (cb->args[0]) { + /* ... of a single resource dump, + * and the resource iterator has been advanced already? */ + if (cb->args[2] && cb->args[2] != cb->args[0]) + return 0; /* DONE. */ + goto dump; + } + + /* First call (from netlink_dump_start). We need to figure out + * which resource(s) the user wants us to dump. */ + nla = nla_find(nlmsg_attrdata(cb->nlh, hdrlen), + nlmsg_attrlen(cb->nlh, hdrlen), + DRBD_NLA_CFG_CONTEXT); + + /* No explicit context given. Dump all. */ + if (!nla) + goto dump; + nla = nla_find_nested(nla, __nla_type(T_ctx_conn_name)); + /* context given, but no name present? */ + if (!nla) + return -EINVAL; + conn_name = nla_data(nla); + tconn = conn_by_name(conn_name); + if (!tconn) + return -ENODEV; + + /* prime iterators, and set "filter" mode mark: + * only dump this tconn. */ + cb->args[0] = (long)tconn; + /* cb->args[1] = 0; passed in this way. */ + cb->args[2] = (long)tconn; + +dump: + return get_one_status(skb, cb); +} + int drbd_adm_get_timeout_type(struct sk_buff *skb, struct genl_info *info) { enum drbd_ret_code retcode; -- 2.20.1