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afs: Move server rotation code into its own file
Move server rotation code into its own file. Signed-off-by: David Howells <dhowells@redhat.com>
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‎fs/afs/Makefile

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@@ -20,6 +20,7 @@ kafs-objs := \
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misc.o \
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mntpt.o \
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proc.o \
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rotate.o \
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rxrpc.o \
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security.o \
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server.o \

‎fs/afs/rotate.c

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@@ -0,0 +1,254 @@
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/* Handle fileserver selection and rotation.
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*
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* Copyright (C) 2017 Red Hat, Inc. All Rights Reserved.
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* Written by David Howells (dhowells@redhat.com)
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public Licence
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* as published by the Free Software Foundation; either version
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* 2 of the Licence, or (at your option) any later version.
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*/
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#include <linux/kernel.h>
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#include <linux/slab.h>
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#include "internal.h"
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/*
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* Initialise a filesystem server cursor for iterating over FS servers.
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*/
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void afs_init_fs_cursor(struct afs_fs_cursor *fc, struct afs_vnode *vnode)
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{
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memset(fc, 0, sizeof(*fc));
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}
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/*
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* Set a filesystem server cursor for using a specific FS server.
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*/
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int afs_set_fs_cursor(struct afs_fs_cursor *fc, struct afs_vnode *vnode)
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{
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afs_init_fs_cursor(fc, vnode);
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read_seqlock_excl(&vnode->cb_lock);
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if (vnode->cb_interest) {
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if (vnode->cb_interest->server->fs_state == 0)
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fc->server = afs_get_server(vnode->cb_interest->server);
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else
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fc->ac.error = vnode->cb_interest->server->fs_state;
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} else {
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fc->ac.error = -ESTALE;
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}
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read_sequnlock_excl(&vnode->cb_lock);
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return fc->ac.error;
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}
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/*
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* pick a server to use to try accessing this volume
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* - returns with an elevated usage count on the server chosen
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*/
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bool afs_volume_pick_fileserver(struct afs_fs_cursor *fc, struct afs_vnode *vnode)
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{
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struct afs_volume *volume = vnode->volume;
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struct afs_server *server;
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int ret, state, loop;
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_enter("%s", volume->vlocation->vldb.name);
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/* stick with the server we're already using if we can */
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if (vnode->cb_interest && vnode->cb_interest->server->fs_state == 0) {
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fc->server = afs_get_server(vnode->cb_interest->server);
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goto set_server;
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}
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down_read(&volume->server_sem);
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/* handle the no-server case */
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if (volume->nservers == 0) {
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fc->ac.error = volume->rjservers ? -ENOMEDIUM : -ESTALE;
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up_read(&volume->server_sem);
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_leave(" = f [no servers %d]", fc->ac.error);
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return false;
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}
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/* basically, just search the list for the first live server and use
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* that */
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ret = 0;
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for (loop = 0; loop < volume->nservers; loop++) {
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server = volume->servers[loop];
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state = server->fs_state;
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_debug("consider %d [%d]", loop, state);
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switch (state) {
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case 0:
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goto picked_server;
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case -ENETUNREACH:
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if (ret == 0)
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ret = state;
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break;
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case -EHOSTUNREACH:
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if (ret == 0 ||
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ret == -ENETUNREACH)
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ret = state;
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break;
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case -ECONNREFUSED:
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if (ret == 0 ||
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ret == -ENETUNREACH ||
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ret == -EHOSTUNREACH)
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ret = state;
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break;
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default:
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case -EREMOTEIO:
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if (ret == 0 ||
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ret == -ENETUNREACH ||
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ret == -EHOSTUNREACH ||
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ret == -ECONNREFUSED)
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ret = state;
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break;
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}
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}
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error:
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fc->ac.error = ret;
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/* no available servers
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* - TODO: handle the no active servers case better
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*/
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up_read(&volume->server_sem);
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_leave(" = f [%d]", fc->ac.error);
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return false;
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picked_server:
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/* Found an apparently healthy server. We need to register an interest
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* in receiving callbacks before we talk to it.
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*/
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ret = afs_register_server_cb_interest(vnode,
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&volume->cb_interests[loop], server);
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if (ret < 0)
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goto error;
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fc->server = afs_get_server(server);
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up_read(&volume->server_sem);
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set_server:
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fc->ac.alist = afs_get_addrlist(fc->server->addrs);
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fc->ac.addr = &fc->ac.alist->addrs[0];
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_debug("USING SERVER: %pIS\n", &fc->ac.addr->transport);
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_leave(" = t (picked %pIS)", &fc->ac.addr->transport);
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return true;
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}
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/*
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* release a server after use
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* - releases the ref on the server struct that was acquired by picking
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* - records result of using a particular server to access a volume
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* - return true to try again, false if okay or to issue error
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* - the caller must release the server struct if result was false
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*/
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bool afs_iterate_fs_cursor(struct afs_fs_cursor *fc,
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struct afs_vnode *vnode)
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{
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struct afs_volume *volume = vnode->volume;
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struct afs_server *server = fc->server;
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unsigned loop;
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_enter("%s,%pIS,%d",
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volume->vlocation->vldb.name, &fc->ac.addr->transport,
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fc->ac.error);
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switch (fc->ac.error) {
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/* success */
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case 0:
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server->fs_state = 0;
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_leave(" = f");
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return false;
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/* the fileserver denied all knowledge of the volume */
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case -ENOMEDIUM:
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down_write(&volume->server_sem);
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/* firstly, find where the server is in the active list (if it
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* is) */
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for (loop = 0; loop < volume->nservers; loop++)
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if (volume->servers[loop] == server)
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goto present;
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/* no longer there - may have been discarded by another op */
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goto try_next_server_upw;
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present:
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volume->nservers--;
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memmove(&volume->servers[loop],
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&volume->servers[loop + 1],
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sizeof(volume->servers[loop]) *
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(volume->nservers - loop));
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volume->servers[volume->nservers] = NULL;
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afs_put_server(afs_v2net(vnode), server);
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volume->rjservers++;
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if (volume->nservers > 0)
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/* another server might acknowledge its existence */
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goto try_next_server_upw;
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/* handle the case where all the fileservers have rejected the
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* volume
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* - TODO: try asking the fileservers for volume information
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* - TODO: contact the VL server again to see if the volume is
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* no longer registered
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*/
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up_write(&volume->server_sem);
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afs_put_server(afs_v2net(vnode), server);
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fc->server = NULL;
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_leave(" = f [completely rejected]");
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return false;
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/* problem reaching the server */
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case -ENETUNREACH:
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case -EHOSTUNREACH:
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case -ECONNREFUSED:
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case -ETIME:
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case -ETIMEDOUT:
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case -EREMOTEIO:
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/* mark the server as dead
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* TODO: vary dead timeout depending on error
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*/
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spin_lock(&server->fs_lock);
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if (!server->fs_state) {
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server->fs_state = fc->ac.error;
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printk("kAFS: SERVER DEAD state=%d\n", fc->ac.error);
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}
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spin_unlock(&server->fs_lock);
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goto try_next_server;
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/* miscellaneous error */
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default:
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case -ENOMEM:
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case -ENONET:
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/* tell the caller to accept the result */
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afs_put_server(afs_v2net(vnode), server);
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fc->server = NULL;
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_leave(" = f [local failure]");
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return false;
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}
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/* tell the caller to loop around and try the next server */
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try_next_server_upw:
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up_write(&volume->server_sem);
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try_next_server:
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afs_put_server(afs_v2net(vnode), server);
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_leave(" = t [try next server]");
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return true;
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}
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/*
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* Clean up a fileserver cursor.
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*/
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int afs_end_fs_cursor(struct afs_fs_cursor *fc, struct afs_net *net)
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{
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afs_end_cursor(&fc->ac);
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afs_put_server(net, fc->server);
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return fc->ac.error;
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}

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