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authorDavid Howells <dhowells@redhat.com>2018-10-20 00:57:59 +0100
committerDavid Howells <dhowells@redhat.com>2018-10-24 00:41:09 +0100
commit3bf0fb6f33dd545693da5e65f5b1b9b9f0bfc35e (patch)
treedf215e6a6ad11b6ac8158461144667e168591d28 /fs/afs/rotate.c
parent18ac61853cc4e44eb30e125fc8344a3b25c7b6fe (diff)
downloadlinux-3bf0fb6f33dd545693da5e65f5b1b9b9f0bfc35e.tar.bz2
afs: Probe multiple fileservers simultaneously
Send probes to all the unprobed fileservers in a fileserver list on all addresses simultaneously in an attempt to find out the fastest route whilst not getting stuck for 20s on any server or address that we don't get a reply from. This alleviates the problem whereby attempting to access a new server can take a long time because the rotation algorithm ends up rotating through all servers and addresses until it finds one that responds. Signed-off-by: David Howells <dhowells@redhat.com>
Diffstat (limited to 'fs/afs/rotate.c')
-rw-r--r--fs/afs/rotate.c174
1 files changed, 114 insertions, 60 deletions
diff --git a/fs/afs/rotate.c b/fs/afs/rotate.c
index 7c4487781637..00504254c1c2 100644
--- a/fs/afs/rotate.c
+++ b/fs/afs/rotate.c
@@ -19,14 +19,6 @@
#include "afs_fs.h"
/*
- * Initialise a filesystem server cursor for iterating over FS servers.
- */
-static void afs_init_fs_cursor(struct afs_fs_cursor *fc, struct afs_vnode *vnode)
-{
- memset(fc, 0, sizeof(*fc));
-}
-
-/*
* Begin an operation on the fileserver.
*
* Fileserver operations are serialised on the server by vnode, so we serialise
@@ -35,7 +27,7 @@ static void afs_init_fs_cursor(struct afs_fs_cursor *fc, struct afs_vnode *vnode
bool afs_begin_vnode_operation(struct afs_fs_cursor *fc, struct afs_vnode *vnode,
struct key *key)
{
- afs_init_fs_cursor(fc, vnode);
+ memset(fc, 0, sizeof(*fc));
fc->vnode = vnode;
fc->key = key;
fc->ac.error = SHRT_MAX;
@@ -66,12 +58,15 @@ static bool afs_start_fs_iteration(struct afs_fs_cursor *fc,
fc->server_list = afs_get_serverlist(vnode->volume->servers);
read_unlock(&vnode->volume->servers_lock);
+ fc->untried = (1UL << fc->server_list->nr_servers) - 1;
+ fc->index = READ_ONCE(fc->server_list->preferred);
+
cbi = vnode->cb_interest;
if (cbi) {
/* See if the vnode's preferred record is still available */
for (i = 0; i < fc->server_list->nr_servers; i++) {
if (fc->server_list->servers[i].cb_interest == cbi) {
- fc->start = i;
+ fc->index = i;
goto found_interest;
}
}
@@ -95,12 +90,9 @@ static bool afs_start_fs_iteration(struct afs_fs_cursor *fc,
afs_put_cb_interest(afs_v2net(vnode), cbi);
cbi = NULL;
- } else {
- fc->start = READ_ONCE(fc->server_list->index);
}
found_interest:
- fc->index = fc->start;
return true;
}
@@ -144,11 +136,12 @@ bool afs_select_fileserver(struct afs_fs_cursor *fc)
struct afs_addr_list *alist;
struct afs_server *server;
struct afs_vnode *vnode = fc->vnode;
- int error = fc->ac.error;
+ u32 rtt, abort_code;
+ int error = fc->ac.error, i;
- _enter("%u/%u,%u/%u,%d,%d",
- fc->index, fc->start,
- fc->ac.index, fc->ac.start,
+ _enter("%lx[%d],%lx[%d],%d,%d",
+ fc->untried, fc->index,
+ fc->ac.tried, fc->ac.index,
error, fc->ac.abort_code);
if (fc->flags & AFS_FS_CURSOR_STOP) {
@@ -345,8 +338,50 @@ start:
if (!afs_start_fs_iteration(fc, vnode))
goto failed;
-use_server:
- _debug("use");
+ _debug("__ VOL %llx __", vnode->volume->vid);
+ error = afs_probe_fileservers(afs_v2net(vnode), fc->key, fc->server_list);
+ if (error < 0)
+ goto failed_set_error;
+
+pick_server:
+ _debug("pick [%lx]", fc->untried);
+
+ error = afs_wait_for_fs_probes(fc->server_list, fc->untried);
+ if (error < 0)
+ goto failed_set_error;
+
+ /* Pick the untried server with the lowest RTT. If we have outstanding
+ * callbacks, we stick with the server we're already using if we can.
+ */
+ if (fc->cbi) {
+ _debug("cbi %u", fc->index);
+ if (test_bit(fc->index, &fc->untried))
+ goto selected_server;
+ afs_put_cb_interest(afs_v2net(vnode), fc->cbi);
+ fc->cbi = NULL;
+ _debug("nocbi");
+ }
+
+ fc->index = -1;
+ rtt = U32_MAX;
+ for (i = 0; i < fc->server_list->nr_servers; i++) {
+ struct afs_server *s = fc->server_list->servers[i].server;
+
+ if (!test_bit(i, &fc->untried) || !s->probe.responded)
+ continue;
+ if (s->probe.rtt < rtt) {
+ fc->index = i;
+ rtt = s->probe.rtt;
+ }
+ }
+
+ if (fc->index == -1)
+ goto no_more_servers;
+
+selected_server:
+ _debug("use %d", fc->index);
+ __clear_bit(fc->index, &fc->untried);
+
/* We're starting on a different fileserver from the list. We need to
* check it, create a callback intercept, find its address list and
* probe its capabilities before we use it.
@@ -379,60 +414,81 @@ use_server:
memset(&fc->ac, 0, sizeof(fc->ac));
- /* Probe the current fileserver if we haven't done so yet. */
- if (!test_bit(AFS_SERVER_FL_PROBED, &server->flags)) {
- fc->ac.alist = afs_get_addrlist(alist);
-
- if (!afs_probe_fileserver(fc)) {
- switch (fc->ac.error) {
- case -ENOMEM:
- case -ERESTARTSYS:
- case -EINTR:
- goto failed;
- default:
- goto next_server;
- }
- }
- }
-
if (!fc->ac.alist)
fc->ac.alist = alist;
else
afs_put_addrlist(alist);
- fc->ac.start = READ_ONCE(alist->index);
- fc->ac.index = fc->ac.start;
+ fc->ac.index = -1;
iterate_address:
ASSERT(fc->ac.alist);
- _debug("iterate %d/%d", fc->ac.index, fc->ac.alist->nr_addrs);
/* Iterate over the current server's address list to try and find an
* address on which it will respond to us.
*/
if (!afs_iterate_addresses(&fc->ac))
goto next_server;
+ _debug("address [%u] %u/%u", fc->index, fc->ac.index, fc->ac.alist->nr_addrs);
+
_leave(" = t");
return true;
next_server:
_debug("next");
afs_end_cursor(&fc->ac);
- afs_put_cb_interest(afs_v2net(vnode), fc->cbi);
- fc->cbi = NULL;
- fc->index++;
- if (fc->index >= fc->server_list->nr_servers)
- fc->index = 0;
- if (fc->index != fc->start)
- goto use_server;
+ goto pick_server;
+no_more_servers:
/* That's all the servers poked to no good effect. Try again if some
* of them were busy.
*/
if (fc->flags & AFS_FS_CURSOR_VBUSY)
goto restart_from_beginning;
- goto failed;
+ abort_code = 0;
+ error = -EDESTADDRREQ;
+ for (i = 0; i < fc->server_list->nr_servers; i++) {
+ struct afs_server *s = fc->server_list->servers[i].server;
+ int probe_error = READ_ONCE(s->probe.error);
+
+ switch (probe_error) {
+ case 0:
+ continue;
+ default:
+ if (error == -ETIMEDOUT ||
+ error == -ETIME)
+ continue;
+ case -ETIMEDOUT:
+ case -ETIME:
+ if (error == -ENOMEM ||
+ error == -ENONET)
+ continue;
+ case -ENOMEM:
+ case -ENONET:
+ if (error == -ENETUNREACH)
+ continue;
+ case -ENETUNREACH:
+ if (error == -EHOSTUNREACH)
+ continue;
+ case -EHOSTUNREACH:
+ if (error == -ECONNREFUSED)
+ continue;
+ case -ECONNREFUSED:
+ if (error == -ECONNRESET)
+ continue;
+ case -ECONNRESET: /* Responded, but call expired. */
+ if (error == -ECONNABORTED)
+ continue;
+ case -ECONNABORTED:
+ abort_code = s->probe.abort_code;
+ error = probe_error;
+ continue;
+ }
+ }
+
+ if (error == -ECONNABORTED)
+ error = afs_abort_to_error(abort_code);
failed_set_error:
fc->error = error;
@@ -480,8 +536,7 @@ bool afs_select_current_fileserver(struct afs_fs_cursor *fc)
memset(&fc->ac, 0, sizeof(fc->ac));
fc->ac.alist = alist;
- fc->ac.start = READ_ONCE(alist->index);
- fc->ac.index = fc->ac.start;
+ fc->ac.index = -1;
goto iterate_address;
case 0:
@@ -538,13 +593,13 @@ static void afs_dump_edestaddrreq(const struct afs_fs_cursor *fc)
pr_notice("EDESTADDR occurred\n");
pr_notice("FC: cbb=%x cbb2=%x fl=%hx err=%hd\n",
fc->cb_break, fc->cb_break_2, fc->flags, fc->error);
- pr_notice("FC: st=%u ix=%u ni=%u\n",
- fc->start, fc->index, fc->nr_iterations);
+ pr_notice("FC: ut=%lx ix=%d ni=%u\n",
+ fc->untried, fc->index, fc->nr_iterations);
if (fc->server_list) {
const struct afs_server_list *sl = fc->server_list;
- pr_notice("FC: SL nr=%u ix=%u vnov=%hx\n",
- sl->nr_servers, sl->index, sl->vnovol_mask);
+ pr_notice("FC: SL nr=%u pr=%u vnov=%hx\n",
+ sl->nr_servers, sl->preferred, sl->vnovol_mask);
for (i = 0; i < sl->nr_servers; i++) {
const struct afs_server *s = sl->servers[i].server;
pr_notice("FC: server fl=%lx av=%u %pU\n",
@@ -552,22 +607,21 @@ static void afs_dump_edestaddrreq(const struct afs_fs_cursor *fc)
if (s->addresses) {
const struct afs_addr_list *a =
rcu_dereference(s->addresses);
- pr_notice("FC: - av=%u nr=%u/%u/%u ax=%u\n",
+ pr_notice("FC: - av=%u nr=%u/%u/%u pr=%u\n",
a->version,
a->nr_ipv4, a->nr_addrs, a->max_addrs,
- a->index);
- pr_notice("FC: - pr=%lx yf=%lx\n",
- a->probed, a->yfs);
+ a->preferred);
+ pr_notice("FC: - pr=%lx R=%lx F=%lx\n",
+ a->probed, a->responded, a->failed);
if (a == fc->ac.alist)
pr_notice("FC: - current\n");
}
}
}
- pr_notice("AC: as=%u ax=%u ac=%d er=%d b=%u r=%u ni=%u\n",
- fc->ac.start, fc->ac.index, fc->ac.abort_code, fc->ac.error,
- fc->ac.begun, fc->ac.responded, fc->ac.nr_iterations);
-
+ pr_notice("AC: t=%lx ax=%u ac=%d er=%d r=%u ni=%u\n",
+ fc->ac.tried, fc->ac.index, fc->ac.abort_code, fc->ac.error,
+ fc->ac.responded, fc->ac.nr_iterations);
rcu_read_unlock();
}