mirror of
git://sourceware.org/git/lvm2.git
synced 2024-12-21 13:34:40 +03:00
Reread global state the lvmetad copy is stale
This is the client side handling of the global_invalid state added to lvmetad in commit c595b50cec8a6b95c6ac4988912d1412f3cc0237. The function added here: . checks if the global state in lvmetad is invalid . if so, scans disks to update the state in lvmetad . clears the global_invalid flag in lvmetad . updates the local udev db to reflect any changes
This commit is contained in:
David Teigland
parent
679b6b5b29
commit
c23e7ff2a0
296
lib/cache/lvmetad.c
vendored
296
lib/cache/lvmetad.c
vendored
@ -1283,3 +1283,299 @@ int lvmetad_vg_clear_outdated_pvs(struct volume_group *vg)
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return result;
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}
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/*
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* Records the state of cached PVs in lvmetad so we can look for changes
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* after rescanning.
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*/
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struct pv_cache_list {
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struct dm_list list;
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dev_t devt;
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struct id pvid;
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const char *vgid;
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unsigned found : 1;
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unsigned update_udev : 1;
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};
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/*
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* Get the list of PVs known to lvmetad.
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*/
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static int _lvmetad_get_pv_cache_list(struct cmd_context *cmd, struct dm_list *pvc_list)
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{
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daemon_reply reply;
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struct dm_config_node *cn;
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struct pv_cache_list *pvcl;
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const char *pvid_txt;
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const char *vgid;
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if (!lvmetad_active())
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return 1;
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log_debug_lvmetad("Asking lvmetad for complete list of known PVs");
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reply = _lvmetad_send("pv_list", NULL);
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if (!_lvmetad_handle_reply(reply, "list PVs", "", NULL)) {
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log_error("lvmetad message failed.");
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daemon_reply_destroy(reply);
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return_0;
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}
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if ((cn = dm_config_find_node(reply.cft->root, "physical_volumes"))) {
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for (cn = cn->child; cn; cn = cn->sib) {
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if (!(pvcl = dm_pool_zalloc(cmd->mem, sizeof(*pvcl)))) {
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log_error("pv_cache_list allocation failed.");
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return 0;
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}
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pvid_txt = cn->key;
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if (!id_read_format(&pvcl->pvid, pvid_txt)) {
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stack;
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continue;
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}
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pvcl->devt = dm_config_find_int(cn->child, "device", 0);
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if ((vgid = dm_config_find_str(cn->child, "vgid", NULL)))
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pvcl->vgid = dm_pool_strdup(cmd->mem, vgid);
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dm_list_add(pvc_list, &pvcl->list);
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}
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}
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daemon_reply_destroy(reply);
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return 1;
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}
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/*
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* Opening the device RDWR should trigger a udev db update.
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* FIXME: is there a better way to update the udev db than
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* doing an open/close of the device?
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*/
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static void _update_pv_in_udev(struct cmd_context *cmd, dev_t devt)
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{
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struct device *dev;
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log_debug_devs("device %d:%d open to update udev",
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(int)MAJOR(devt), (int)MINOR(devt));
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if (!(dev = dev_cache_get_by_devt(devt, cmd->lvmetad_filter))) {
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log_error("_update_pv_in_udev no dev found");
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return;
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}
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if (!dev_open(dev))
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return;
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dev_close(dev);
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}
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/*
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* Compare before and after PV lists from before/after rescanning,
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* and update udev db for changes.
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*
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* For PVs that have changed pvid or vgid in lvmetad from rescanning,
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* there may be information in the udev database to update, so open
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* these devices to trigger a udev update.
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*
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* "before" refers to the list of pvs from lvmetad before rescanning
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* "after" refers to the list of pvs from lvmetad after rescanning
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*
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* Comparing both lists, we can see which PVs changed (pvid or vgid),
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* and trigger a udev db update for those.
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*/
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static void _update_changed_pvs_in_udev(struct cmd_context *cmd,
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struct dm_list *pvc_before,
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struct dm_list *pvc_after)
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{
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struct pv_cache_list *before;
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struct pv_cache_list *after;
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char id_before[ID_LEN + 1] __attribute__((aligned(8)));
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char id_after[ID_LEN + 1] __attribute__((aligned(8)));
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int found;
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dm_list_iterate_items(before, pvc_before) {
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found = 0;
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dm_list_iterate_items(after, pvc_after) {
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if (after->found)
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continue;
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if (before->devt != after->devt)
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continue;
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if (!id_equal(&before->pvid, &after->pvid)) {
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memset(id_before, 0, sizeof(id_before));
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memset(id_after, 0, sizeof(id_after));
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strncpy(&id_before[0], (char *) &before->pvid, sizeof(id_before) - 1);
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strncpy(&id_after[0], (char *) &after->pvid, sizeof(id_after) - 1);
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log_debug_devs("device %d:%d changed pvid from %s to %s",
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(int)MAJOR(before->devt), (int)MINOR(before->devt),
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id_before, id_after);
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before->update_udev = 1;
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} else if ((before->vgid && !after->vgid) ||
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(after->vgid && !before->vgid) ||
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(before->vgid && after->vgid && strcmp(before->vgid, after->vgid))) {
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log_debug_devs("device %d:%d changed vg from %s to %s",
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(int)MAJOR(before->devt), (int)MINOR(before->devt),
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before->vgid ?: "none", after->vgid ?: "none");
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before->update_udev = 1;
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}
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after->found = 1;
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before->found = 1;
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found = 1;
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break;
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}
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if (!found) {
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memset(id_before, 0, sizeof(id_before));
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strncpy(&id_before[0], (char *) &before->pvid, sizeof(id_before) - 1);
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log_debug_devs("device %d:%d pvid %s vg %s is gone",
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(int)MAJOR(before->devt), (int)MINOR(before->devt),
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id_before, before->vgid ? before->vgid : "none");
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before->update_udev = 1;
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}
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}
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dm_list_iterate_items(before, pvc_before) {
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if (before->update_udev)
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_update_pv_in_udev(cmd, before->devt);
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}
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dm_list_iterate_items(after, pvc_after) {
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if (after->update_udev)
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_update_pv_in_udev(cmd, after->devt);
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}
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}
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/*
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* Before this command was run, some external entity may have
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* invalidated lvmetad's cache of global information, e.g. lvmlockd.
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*
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* The global information includes things like a new VG, a
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* VG that was removed, the assignment of a PV to a VG;
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* any change that is not isolated within a single VG.
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*
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* The external entity, like a lock manager, would invalidate
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* the lvmetad global cache if it detected that the global
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* information had been changed on disk by something other
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* than a local lvm command, e.g. an lvm command on another
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* host with access to the same devices. (How it detects
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* the change is specific to lock manager or other entity.)
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*
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* The effect is that metadata on disk is newer than the metadata
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* in the local lvmetad daemon, and the local lvmetad's cache
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* should be updated from disk before this command uses it.
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*
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* So, using this function, a command checks if lvmetad's global
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* cache is valid. If so, it does nothing. If not, it rescans
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* devices to update the lvmetad cache, then it notifies lvmetad
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* that it's cache is valid again (consistent with what's on disk.)
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* This command can then go ahead and use the newly refreshed metadata.
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*
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* 1. Check if the lvmetad global cache is invalid.
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* 2. If so, reread metadata from all devices and update the lvmetad cache.
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* 3. Tell lvmetad that the global cache is now valid.
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*/
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void lvmetad_validate_global_cache(struct cmd_context *cmd, int force)
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{
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struct dm_list pvc_before; /* pv_cache_list */
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struct dm_list pvc_after; /* pv_cache_list */
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daemon_reply reply;
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int global_invalid;
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dm_list_init(&pvc_before);
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dm_list_init(&pvc_after);
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if (!lvmetad_used())
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return;
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if (force)
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goto do_scan;
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reply = daemon_send_simple(_lvmetad, "get_global_info",
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"token = %s", "skip",
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NULL);
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if (reply.error) {
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log_error("lvmetad_validate_global_cache get_global_info error %d", reply.error);
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goto do_scan;
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}
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if (strcmp(daemon_reply_str(reply, "response", ""), "OK")) {
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log_error("lvmetad_validate_global_cache get_global_info not ok");
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goto do_scan;
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}
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global_invalid = daemon_reply_int(reply, "global_invalid", -1);
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daemon_reply_destroy(reply);
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if (!global_invalid) {
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/* cache is valid */
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return;
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}
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do_scan:
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/*
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* Save the current state of pvs from lvmetad so after devices are
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* scanned, we can compare to the new state to see if pvs changed.
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*/
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_lvmetad_get_pv_cache_list(cmd, &pvc_before);
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/*
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* Update the local lvmetad cache so it correctly reflects any
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* changes made on remote hosts.
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*/
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lvmetad_pvscan_all_devs(cmd, NULL);
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/*
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* Clear the global_invalid flag in lvmetad.
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* Subsequent local commands that read global state
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* from lvmetad will not see global_invalid until
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* another host makes another global change.
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*/
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reply = daemon_send_simple(_lvmetad, "set_global_info",
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"token = %s", "skip",
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"global_invalid = %d", 0,
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NULL);
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if (reply.error)
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log_error("lvmetad_validate_global_cache set_global_info error %d", reply.error);
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if (strcmp(daemon_reply_str(reply, "response", ""), "OK"))
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log_error("lvmetad_validate_global_cache set_global_info not ok");
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daemon_reply_destroy(reply);
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/*
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* Populate this command's lvmcache structures from lvmetad.
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*/
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lvmcache_seed_infos_from_lvmetad(cmd);
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/*
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* Update the local udev database to reflect PV changes from
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* other hosts.
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*
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* Compare the before and after PV lists, and if a PV's
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* pvid or vgid has changed, then open that device to trigger
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* a uevent to update the udev db.
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*
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* This has no direct benefit to lvm, but is just a best effort
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* attempt to keep the udev db updated and reflecting current
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* lvm information.
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*
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* FIXME: lvmcache_seed_infos_from_lvmetad() and _lvmetad_get_pv_cache_list()
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* each get pv_list from lvmetad, and they could share a single pv_list reply.
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*/
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if (!dm_list_empty(&pvc_before)) {
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_lvmetad_get_pv_cache_list(cmd, &pvc_after);
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_update_changed_pvs_in_udev(cmd, &pvc_before, &pvc_after);
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}
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}
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2
lib/cache/lvmetad.h
vendored
2
lib/cache/lvmetad.h
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@ -167,6 +167,7 @@ int lvmetad_pvscan_all_devs(struct cmd_context *cmd, activation_handler handler)
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int lvmetad_pvscan_foreign_vgs(struct cmd_context *cmd, activation_handler handler);
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int lvmetad_vg_clear_outdated_pvs(struct volume_group *vg);
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void lvmetad_validate_global_cache(struct cmd_context *cmd, int force);
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# else /* LVMETAD_SUPPORT */
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@ -195,6 +196,7 @@ int lvmetad_vg_clear_outdated_pvs(struct volume_group *vg);
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# define lvmetad_pvscan_all_devs(cmd, handler) (0)
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# define lvmetad_pvscan_foreign_vgs(cmd, handler) (0)
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# define lvmetad_vg_clear_outdated_pvs(vg) (1)
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# define lvmetad_validate_global_cache(cmd, force) do { } while (0)
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# endif /* LVMETAD_SUPPORT */
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