afs: Implement VL server rotation
Track VL servers as independent entities rather than lumping all their
addresses together into one set and implement server-level rotation by:
(1) Add the concept of a VL server list, where each server has its own
separate address list. This code is similar to the FS server list.
(2) Use the DNS resolver to retrieve a set of servers and their associated
addresses, ports, preference and weight ratings.
(3) In the case of a legacy DNS resolver or an address list given directly
through /proc/net/afs/cells, create a list containing just a dummy
server record and attach all the addresses to that.
(4) Implement a simple rotation policy, for the moment ignoring the
priorities and weights assigned to the servers.
(5) Show the address list through /proc/net/afs/<cell>/vlservers. This
also displays the source and status of the data as indicated by the
upcall.
Signed-off-by: David Howells <dhowells@redhat.com>
diff --git a/fs/afs/cell.c b/fs/afs/cell.c
index 6127f0f..963b6fa 100644
--- a/fs/afs/cell.c
+++ b/fs/afs/cell.c
@@ -119,7 +119,7 @@ struct afs_cell *afs_lookup_cell_rcu(struct afs_net *net,
*/
static struct afs_cell *afs_alloc_cell(struct afs_net *net,
const char *name, unsigned int namelen,
- const char *vllist)
+ const char *addresses)
{
struct afs_cell *cell;
int i, ret;
@@ -134,7 +134,7 @@ static struct afs_cell *afs_alloc_cell(struct afs_net *net,
if (namelen == 5 && memcmp(name, "@cell", 5) == 0)
return ERR_PTR(-EINVAL);
- _enter("%*.*s,%s", namelen, namelen, name, vllist);
+ _enter("%*.*s,%s", namelen, namelen, name, addresses);
cell = kzalloc(sizeof(struct afs_cell), GFP_KERNEL);
if (!cell) {
@@ -153,22 +153,23 @@ static struct afs_cell *afs_alloc_cell(struct afs_net *net,
(1 << AFS_CELL_FL_NO_LOOKUP_YET));
INIT_LIST_HEAD(&cell->proc_volumes);
rwlock_init(&cell->proc_lock);
- rwlock_init(&cell->vl_addrs_lock);
+ rwlock_init(&cell->vl_servers_lock);
/* Fill in the VL server list if we were given a list of addresses to
* use.
*/
- if (vllist) {
- struct afs_addr_list *alist;
+ if (addresses) {
+ struct afs_vlserver_list *vllist;
- alist = afs_parse_text_addrs(vllist, strlen(vllist), ':',
- VL_SERVICE, AFS_VL_PORT);
- if (IS_ERR(alist)) {
- ret = PTR_ERR(alist);
+ vllist = afs_parse_text_addrs(net,
+ addresses, strlen(addresses), ':',
+ VL_SERVICE, AFS_VL_PORT);
+ if (IS_ERR(vllist)) {
+ ret = PTR_ERR(vllist);
goto parse_failed;
}
- rcu_assign_pointer(cell->vl_addrs, alist);
+ rcu_assign_pointer(cell->vl_servers, vllist);
cell->dns_expiry = TIME64_MAX;
}
@@ -356,14 +357,14 @@ int afs_cell_init(struct afs_net *net, const char *rootcell)
*/
static void afs_update_cell(struct afs_cell *cell)
{
- struct afs_addr_list *alist, *old;
+ struct afs_vlserver_list *vllist, *old;
time64_t now, expiry;
_enter("%s", cell->name);
- alist = afs_dns_query(cell, &expiry);
- if (IS_ERR(alist)) {
- switch (PTR_ERR(alist)) {
+ vllist = afs_dns_query(cell, &expiry);
+ if (IS_ERR(vllist)) {
+ switch (PTR_ERR(vllist)) {
case -ENODATA:
/* The DNS said that the cell does not exist */
set_bit(AFS_CELL_FL_NOT_FOUND, &cell->flags);
@@ -387,12 +388,12 @@ static void afs_update_cell(struct afs_cell *cell)
/* Exclusion on changing vl_addrs is achieved by a
* non-reentrant work item.
*/
- old = rcu_dereference_protected(cell->vl_addrs, true);
- rcu_assign_pointer(cell->vl_addrs, alist);
+ old = rcu_dereference_protected(cell->vl_servers, true);
+ rcu_assign_pointer(cell->vl_servers, vllist);
cell->dns_expiry = expiry;
if (old)
- afs_put_addrlist(old);
+ afs_put_vlserverlist(cell->net, old);
}
if (test_and_clear_bit(AFS_CELL_FL_NO_LOOKUP_YET, &cell->flags))
@@ -414,7 +415,7 @@ static void afs_cell_destroy(struct rcu_head *rcu)
ASSERTCMP(atomic_read(&cell->usage), ==, 0);
- afs_put_addrlist(rcu_access_pointer(cell->vl_addrs));
+ afs_put_vlserverlist(cell->net, rcu_access_pointer(cell->vl_servers));
key_put(cell->anonymous_key);
kfree(cell);