v4.19.13 snapshot.
diff --git a/fs/afs/rotate.c b/fs/afs/rotate.c
new file mode 100644
index 0000000..1faef56
--- /dev/null
+++ b/fs/afs/rotate.c
@@ -0,0 +1,528 @@
+/* Handle fileserver selection and rotation.
+ *
+ * Copyright (C) 2017 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public Licence
+ * as published by the Free Software Foundation; either version
+ * 2 of the Licence, or (at your option) any later version.
+ */
+
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/fs.h>
+#include <linux/sched.h>
+#include <linux/delay.h>
+#include <linux/sched/signal.h>
+#include "internal.h"
+#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
+ * them here also using the io_lock.
+ */
+bool afs_begin_vnode_operation(struct afs_fs_cursor *fc, struct afs_vnode *vnode,
+ struct key *key)
+{
+ afs_init_fs_cursor(fc, vnode);
+ fc->vnode = vnode;
+ fc->key = key;
+ fc->ac.error = SHRT_MAX;
+
+ if (mutex_lock_interruptible(&vnode->io_lock) < 0) {
+ fc->ac.error = -EINTR;
+ fc->flags |= AFS_FS_CURSOR_STOP;
+ return false;
+ }
+
+ if (vnode->lock_state != AFS_VNODE_LOCK_NONE)
+ fc->flags |= AFS_FS_CURSOR_CUR_ONLY;
+ return true;
+}
+
+/*
+ * Begin iteration through a server list, starting with the vnode's last used
+ * server if possible, or the last recorded good server if not.
+ */
+static bool afs_start_fs_iteration(struct afs_fs_cursor *fc,
+ struct afs_vnode *vnode)
+{
+ struct afs_cb_interest *cbi;
+ int i;
+
+ read_lock(&vnode->volume->servers_lock);
+ fc->server_list = afs_get_serverlist(vnode->volume->servers);
+ read_unlock(&vnode->volume->servers_lock);
+
+ 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;
+ goto found_interest;
+ }
+ }
+
+ /* If we have a lock outstanding on a server that's no longer
+ * serving this vnode, then we can't switch to another server
+ * and have to return an error.
+ */
+ if (fc->flags & AFS_FS_CURSOR_CUR_ONLY) {
+ fc->ac.error = -ESTALE;
+ return false;
+ }
+
+ /* Note that the callback promise is effectively broken */
+ write_seqlock(&vnode->cb_lock);
+ ASSERTCMP(cbi, ==, vnode->cb_interest);
+ vnode->cb_interest = NULL;
+ if (test_and_clear_bit(AFS_VNODE_CB_PROMISED, &vnode->flags))
+ vnode->cb_break++;
+ write_sequnlock(&vnode->cb_lock);
+
+ 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;
+}
+
+/*
+ * Post volume busy note.
+ */
+static void afs_busy(struct afs_volume *volume, u32 abort_code)
+{
+ const char *m;
+
+ switch (abort_code) {
+ case VOFFLINE: m = "offline"; break;
+ case VRESTARTING: m = "restarting"; break;
+ case VSALVAGING: m = "being salvaged"; break;
+ default: m = "busy"; break;
+ }
+
+ pr_notice("kAFS: Volume %u '%s' is %s\n", volume->vid, volume->name, m);
+}
+
+/*
+ * Sleep and retry the operation to the same fileserver.
+ */
+static bool afs_sleep_and_retry(struct afs_fs_cursor *fc)
+{
+ msleep_interruptible(1000);
+ if (signal_pending(current)) {
+ fc->ac.error = -ERESTARTSYS;
+ return false;
+ }
+
+ return true;
+}
+
+/*
+ * Select the fileserver to use. May be called multiple times to rotate
+ * through the fileservers.
+ */
+bool afs_select_fileserver(struct afs_fs_cursor *fc)
+{
+ struct afs_addr_list *alist;
+ struct afs_server *server;
+ struct afs_vnode *vnode = fc->vnode;
+
+ _enter("%u/%u,%u/%u,%d,%d",
+ fc->index, fc->start,
+ fc->ac.index, fc->ac.start,
+ fc->ac.error, fc->ac.abort_code);
+
+ if (fc->flags & AFS_FS_CURSOR_STOP) {
+ _leave(" = f [stopped]");
+ return false;
+ }
+
+ /* Evaluate the result of the previous operation, if there was one. */
+ switch (fc->ac.error) {
+ case SHRT_MAX:
+ goto start;
+
+ case 0:
+ default:
+ /* Success or local failure. Stop. */
+ fc->flags |= AFS_FS_CURSOR_STOP;
+ _leave(" = f [okay/local %d]", fc->ac.error);
+ return false;
+
+ case -ECONNABORTED:
+ /* The far side rejected the operation on some grounds. This
+ * might involve the server being busy or the volume having been moved.
+ */
+ switch (fc->ac.abort_code) {
+ case VNOVOL:
+ /* This fileserver doesn't know about the volume.
+ * - May indicate that the VL is wrong - retry once and compare
+ * the results.
+ * - May indicate that the fileserver couldn't attach to the vol.
+ */
+ if (fc->flags & AFS_FS_CURSOR_VNOVOL) {
+ fc->ac.error = -EREMOTEIO;
+ goto next_server;
+ }
+
+ write_lock(&vnode->volume->servers_lock);
+ fc->server_list->vnovol_mask |= 1 << fc->index;
+ write_unlock(&vnode->volume->servers_lock);
+
+ set_bit(AFS_VOLUME_NEEDS_UPDATE, &vnode->volume->flags);
+ fc->ac.error = afs_check_volume_status(vnode->volume, fc->key);
+ if (fc->ac.error < 0)
+ goto failed;
+
+ if (test_bit(AFS_VOLUME_DELETED, &vnode->volume->flags)) {
+ fc->ac.error = -ENOMEDIUM;
+ goto failed;
+ }
+
+ /* If the server list didn't change, then assume that
+ * it's the fileserver having trouble.
+ */
+ if (vnode->volume->servers == fc->server_list) {
+ fc->ac.error = -EREMOTEIO;
+ goto next_server;
+ }
+
+ /* Try again */
+ fc->flags |= AFS_FS_CURSOR_VNOVOL;
+ _leave(" = t [vnovol]");
+ return true;
+
+ case VSALVAGE: /* TODO: Should this return an error or iterate? */
+ case VVOLEXISTS:
+ case VNOSERVICE:
+ case VONLINE:
+ case VDISKFULL:
+ case VOVERQUOTA:
+ fc->ac.error = afs_abort_to_error(fc->ac.abort_code);
+ goto next_server;
+
+ case VOFFLINE:
+ if (!test_and_set_bit(AFS_VOLUME_OFFLINE, &vnode->volume->flags)) {
+ afs_busy(vnode->volume, fc->ac.abort_code);
+ clear_bit(AFS_VOLUME_BUSY, &vnode->volume->flags);
+ }
+ if (fc->flags & AFS_FS_CURSOR_NO_VSLEEP) {
+ fc->ac.error = -EADV;
+ goto failed;
+ }
+ if (fc->flags & AFS_FS_CURSOR_CUR_ONLY) {
+ fc->ac.error = -ESTALE;
+ goto failed;
+ }
+ goto busy;
+
+ case VSALVAGING:
+ case VRESTARTING:
+ case VBUSY:
+ /* Retry after going round all the servers unless we
+ * have a file lock we need to maintain.
+ */
+ if (fc->flags & AFS_FS_CURSOR_NO_VSLEEP) {
+ fc->ac.error = -EBUSY;
+ goto failed;
+ }
+ if (!test_and_set_bit(AFS_VOLUME_BUSY, &vnode->volume->flags)) {
+ afs_busy(vnode->volume, fc->ac.abort_code);
+ clear_bit(AFS_VOLUME_OFFLINE, &vnode->volume->flags);
+ }
+ busy:
+ if (fc->flags & AFS_FS_CURSOR_CUR_ONLY) {
+ if (!afs_sleep_and_retry(fc))
+ goto failed;
+
+ /* Retry with same server & address */
+ _leave(" = t [vbusy]");
+ return true;
+ }
+
+ fc->flags |= AFS_FS_CURSOR_VBUSY;
+ goto next_server;
+
+ case VMOVED:
+ /* The volume migrated to another server. We consider
+ * consider all locks and callbacks broken and request
+ * an update from the VLDB.
+ *
+ * We also limit the number of VMOVED hops we will
+ * honour, just in case someone sets up a loop.
+ */
+ if (fc->flags & AFS_FS_CURSOR_VMOVED) {
+ fc->ac.error = -EREMOTEIO;
+ goto failed;
+ }
+ fc->flags |= AFS_FS_CURSOR_VMOVED;
+
+ set_bit(AFS_VOLUME_WAIT, &vnode->volume->flags);
+ set_bit(AFS_VOLUME_NEEDS_UPDATE, &vnode->volume->flags);
+ fc->ac.error = afs_check_volume_status(vnode->volume, fc->key);
+ if (fc->ac.error < 0)
+ goto failed;
+
+ /* If the server list didn't change, then the VLDB is
+ * out of sync with the fileservers. This is hopefully
+ * a temporary condition, however, so we don't want to
+ * permanently block access to the file.
+ *
+ * TODO: Try other fileservers if we can.
+ *
+ * TODO: Retry a few times with sleeps.
+ */
+ if (vnode->volume->servers == fc->server_list) {
+ fc->ac.error = -ENOMEDIUM;
+ goto failed;
+ }
+
+ goto restart_from_beginning;
+
+ default:
+ clear_bit(AFS_VOLUME_OFFLINE, &vnode->volume->flags);
+ clear_bit(AFS_VOLUME_BUSY, &vnode->volume->flags);
+ fc->ac.error = afs_abort_to_error(fc->ac.abort_code);
+ goto failed;
+ }
+
+ case -ENETUNREACH:
+ case -EHOSTUNREACH:
+ case -ECONNREFUSED:
+ case -ETIMEDOUT:
+ case -ETIME:
+ _debug("no conn");
+ goto iterate_address;
+
+ case -ECONNRESET:
+ _debug("call reset");
+ goto failed;
+ }
+
+restart_from_beginning:
+ _debug("restart");
+ afs_end_cursor(&fc->ac);
+ afs_put_cb_interest(afs_v2net(vnode), fc->cbi);
+ fc->cbi = NULL;
+ afs_put_serverlist(afs_v2net(vnode), fc->server_list);
+ fc->server_list = NULL;
+start:
+ _debug("start");
+ /* See if we need to do an update of the volume record. Note that the
+ * volume may have moved or even have been deleted.
+ */
+ fc->ac.error = afs_check_volume_status(vnode->volume, fc->key);
+ if (fc->ac.error < 0)
+ goto failed;
+
+ if (!afs_start_fs_iteration(fc, vnode))
+ goto failed;
+
+use_server:
+ _debug("use");
+ /* 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.
+ */
+ ASSERTCMP(fc->ac.alist, ==, NULL);
+ server = fc->server_list->servers[fc->index].server;
+
+ if (!afs_check_server_record(fc, server))
+ goto failed;
+
+ _debug("USING SERVER: %pU", &server->uuid);
+
+ /* Make sure we've got a callback interest record for this server. We
+ * have to link it in before we send the request as we can be sent a
+ * break request before we've finished decoding the reply and
+ * installing the vnode.
+ */
+ fc->ac.error = afs_register_server_cb_interest(vnode, fc->server_list,
+ fc->index);
+ if (fc->ac.error < 0)
+ goto failed;
+
+ fc->cbi = afs_get_cb_interest(vnode->cb_interest);
+
+ read_lock(&server->fs_lock);
+ alist = rcu_dereference_protected(server->addresses,
+ lockdep_is_held(&server->fs_lock));
+ afs_get_addrlist(alist);
+ read_unlock(&server->fs_lock);
+
+ 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;
+
+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;
+
+ _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;
+
+ /* 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;
+
+ fc->ac.error = -EDESTADDRREQ;
+ goto failed;
+
+failed:
+ fc->flags |= AFS_FS_CURSOR_STOP;
+ afs_end_cursor(&fc->ac);
+ _leave(" = f [failed %d]", fc->ac.error);
+ return false;
+}
+
+/*
+ * Select the same fileserver we used for a vnode before and only that
+ * fileserver. We use this when we have a lock on that file, which is backed
+ * only by the fileserver we obtained it from.
+ */
+bool afs_select_current_fileserver(struct afs_fs_cursor *fc)
+{
+ struct afs_vnode *vnode = fc->vnode;
+ struct afs_cb_interest *cbi = vnode->cb_interest;
+ struct afs_addr_list *alist;
+
+ _enter("");
+
+ switch (fc->ac.error) {
+ case SHRT_MAX:
+ if (!cbi) {
+ fc->ac.error = -ESTALE;
+ fc->flags |= AFS_FS_CURSOR_STOP;
+ return false;
+ }
+
+ fc->cbi = afs_get_cb_interest(vnode->cb_interest);
+
+ read_lock(&cbi->server->fs_lock);
+ alist = rcu_dereference_protected(cbi->server->addresses,
+ lockdep_is_held(&cbi->server->fs_lock));
+ afs_get_addrlist(alist);
+ read_unlock(&cbi->server->fs_lock);
+ if (!alist) {
+ fc->ac.error = -ESTALE;
+ fc->flags |= AFS_FS_CURSOR_STOP;
+ return false;
+ }
+
+ memset(&fc->ac, 0, sizeof(fc->ac));
+ fc->ac.alist = alist;
+ fc->ac.start = READ_ONCE(alist->index);
+ fc->ac.index = fc->ac.start;
+ goto iterate_address;
+
+ case 0:
+ default:
+ /* Success or local failure. Stop. */
+ fc->flags |= AFS_FS_CURSOR_STOP;
+ _leave(" = f [okay/local %d]", fc->ac.error);
+ return false;
+
+ case -ECONNABORTED:
+ fc->flags |= AFS_FS_CURSOR_STOP;
+ _leave(" = f [abort]");
+ return false;
+
+ case -ENETUNREACH:
+ case -EHOSTUNREACH:
+ case -ECONNREFUSED:
+ case -ETIMEDOUT:
+ case -ETIME:
+ _debug("no conn");
+ goto iterate_address;
+ }
+
+iterate_address:
+ /* 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)) {
+ _leave(" = t");
+ return true;
+ }
+
+ afs_end_cursor(&fc->ac);
+ return false;
+}
+
+/*
+ * Tidy up a filesystem cursor and unlock the vnode.
+ */
+int afs_end_vnode_operation(struct afs_fs_cursor *fc)
+{
+ struct afs_net *net = afs_v2net(fc->vnode);
+ int ret;
+
+ mutex_unlock(&fc->vnode->io_lock);
+
+ afs_end_cursor(&fc->ac);
+ afs_put_cb_interest(net, fc->cbi);
+ afs_put_serverlist(net, fc->server_list);
+
+ ret = fc->ac.error;
+ if (ret == -ECONNABORTED)
+ afs_abort_to_error(fc->ac.abort_code);
+
+ return fc->ac.error;
+}