mirror of https://gitee.com/openkylin/linux.git
517 lines
13 KiB
C
517 lines
13 KiB
C
/* 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 <linux/fs.h>
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#include <linux/sched.h>
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#include <linux/delay.h>
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#include <linux/sched/signal.h>
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#include "internal.h"
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#include "afs_fs.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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static 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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* Begin an operation on the fileserver.
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*
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* Fileserver operations are serialised on the server by vnode, so we serialise
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* them here also using the io_lock.
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*/
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bool afs_begin_vnode_operation(struct afs_fs_cursor *fc, struct afs_vnode *vnode,
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struct key *key)
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{
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afs_init_fs_cursor(fc, vnode);
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fc->vnode = vnode;
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fc->key = key;
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fc->ac.error = SHRT_MAX;
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if (mutex_lock_interruptible(&vnode->io_lock) < 0) {
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fc->ac.error = -EINTR;
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fc->flags |= AFS_FS_CURSOR_STOP;
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return false;
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}
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if (vnode->lock_state != AFS_VNODE_LOCK_NONE)
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fc->flags |= AFS_FS_CURSOR_CUR_ONLY;
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return true;
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}
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/*
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* Begin iteration through a server list, starting with the vnode's last used
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* server if possible, or the last recorded good server if not.
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*/
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static bool afs_start_fs_iteration(struct afs_fs_cursor *fc,
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struct afs_vnode *vnode)
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{
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struct afs_cb_interest *cbi;
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int i;
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read_lock(&vnode->volume->servers_lock);
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fc->server_list = afs_get_serverlist(vnode->volume->servers);
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read_unlock(&vnode->volume->servers_lock);
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cbi = vnode->cb_interest;
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if (cbi) {
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/* See if the vnode's preferred record is still available */
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for (i = 0; i < fc->server_list->nr_servers; i++) {
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if (fc->server_list->servers[i].cb_interest == cbi) {
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fc->start = i;
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goto found_interest;
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}
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}
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/* If we have a lock outstanding on a server that's no longer
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* serving this vnode, then we can't switch to another server
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* and have to return an error.
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*/
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if (fc->flags & AFS_FS_CURSOR_CUR_ONLY) {
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fc->ac.error = -ESTALE;
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return false;
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}
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/* Note that the callback promise is effectively broken */
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write_seqlock(&vnode->cb_lock);
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ASSERTCMP(cbi, ==, vnode->cb_interest);
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vnode->cb_interest = NULL;
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if (test_and_clear_bit(AFS_VNODE_CB_PROMISED, &vnode->flags))
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vnode->cb_break++;
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write_sequnlock(&vnode->cb_lock);
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afs_put_cb_interest(afs_v2net(vnode), cbi);
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cbi = NULL;
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} else {
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fc->start = READ_ONCE(fc->server_list->index);
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}
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found_interest:
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fc->index = fc->start;
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return true;
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}
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/*
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* Post volume busy note.
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*/
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static void afs_busy(struct afs_volume *volume, u32 abort_code)
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{
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const char *m;
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switch (abort_code) {
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case VOFFLINE: m = "offline"; break;
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case VRESTARTING: m = "restarting"; break;
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case VSALVAGING: m = "being salvaged"; break;
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default: m = "busy"; break;
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}
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pr_notice("kAFS: Volume %u '%s' is %s\n", volume->vid, volume->name, m);
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}
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/*
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* Sleep and retry the operation to the same fileserver.
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*/
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static bool afs_sleep_and_retry(struct afs_fs_cursor *fc)
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{
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msleep_interruptible(1000);
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if (signal_pending(current)) {
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fc->ac.error = -ERESTARTSYS;
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return false;
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}
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return true;
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}
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/*
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* Select the fileserver to use. May be called multiple times to rotate
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* through the fileservers.
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*/
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bool afs_select_fileserver(struct afs_fs_cursor *fc)
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{
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struct afs_addr_list *alist;
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struct afs_server *server;
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struct afs_vnode *vnode = fc->vnode;
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_enter("%u/%u,%u/%u,%d,%d",
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fc->index, fc->start,
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fc->ac.index, fc->ac.start,
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fc->ac.error, fc->ac.abort_code);
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if (fc->flags & AFS_FS_CURSOR_STOP) {
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_leave(" = f [stopped]");
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return false;
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}
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/* Evaluate the result of the previous operation, if there was one. */
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switch (fc->ac.error) {
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case SHRT_MAX:
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goto start;
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case 0:
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default:
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/* Success or local failure. Stop. */
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fc->flags |= AFS_FS_CURSOR_STOP;
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_leave(" = f [okay/local %d]", fc->ac.error);
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return false;
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case -ECONNABORTED:
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/* The far side rejected the operation on some grounds. This
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* might involve the server being busy or the volume having been moved.
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*/
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switch (fc->ac.abort_code) {
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case VNOVOL:
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/* This fileserver doesn't know about the volume.
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* - May indicate that the VL is wrong - retry once and compare
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* the results.
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* - May indicate that the fileserver couldn't attach to the vol.
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*/
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if (fc->flags & AFS_FS_CURSOR_VNOVOL) {
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fc->ac.error = -EREMOTEIO;
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goto failed;
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}
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write_lock(&vnode->volume->servers_lock);
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fc->server_list->vnovol_mask |= 1 << fc->index;
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write_unlock(&vnode->volume->servers_lock);
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set_bit(AFS_VOLUME_NEEDS_UPDATE, &vnode->volume->flags);
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fc->ac.error = afs_check_volume_status(vnode->volume, fc->key);
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if (fc->ac.error < 0)
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goto failed;
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if (test_bit(AFS_VOLUME_DELETED, &vnode->volume->flags)) {
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fc->ac.error = -ENOMEDIUM;
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goto failed;
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}
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/* If the server list didn't change, then assume that
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* it's the fileserver having trouble.
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*/
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if (vnode->volume->servers == fc->server_list) {
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fc->ac.error = -EREMOTEIO;
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goto failed;
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}
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/* Try again */
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fc->flags |= AFS_FS_CURSOR_VNOVOL;
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_leave(" = t [vnovol]");
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return true;
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case VSALVAGE: /* TODO: Should this return an error or iterate? */
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case VVOLEXISTS:
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case VNOSERVICE:
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case VONLINE:
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case VDISKFULL:
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case VOVERQUOTA:
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fc->ac.error = afs_abort_to_error(fc->ac.abort_code);
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goto next_server;
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case VOFFLINE:
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if (!test_and_set_bit(AFS_VOLUME_OFFLINE, &vnode->volume->flags)) {
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afs_busy(vnode->volume, fc->ac.abort_code);
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clear_bit(AFS_VOLUME_BUSY, &vnode->volume->flags);
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}
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if (fc->flags & AFS_FS_CURSOR_NO_VSLEEP) {
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fc->ac.error = -EADV;
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goto failed;
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}
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if (fc->flags & AFS_FS_CURSOR_CUR_ONLY) {
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fc->ac.error = -ESTALE;
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goto failed;
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}
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goto busy;
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case VSALVAGING:
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case VRESTARTING:
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case VBUSY:
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/* Retry after going round all the servers unless we
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* have a file lock we need to maintain.
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*/
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if (fc->flags & AFS_FS_CURSOR_NO_VSLEEP) {
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fc->ac.error = -EBUSY;
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goto failed;
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}
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if (!test_and_set_bit(AFS_VOLUME_BUSY, &vnode->volume->flags)) {
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afs_busy(vnode->volume, fc->ac.abort_code);
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clear_bit(AFS_VOLUME_OFFLINE, &vnode->volume->flags);
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}
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busy:
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if (fc->flags & AFS_FS_CURSOR_CUR_ONLY) {
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if (!afs_sleep_and_retry(fc))
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goto failed;
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/* Retry with same server & address */
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_leave(" = t [vbusy]");
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return true;
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}
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fc->flags |= AFS_FS_CURSOR_VBUSY;
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goto next_server;
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case VMOVED:
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/* The volume migrated to another server. We consider
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* consider all locks and callbacks broken and request
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* an update from the VLDB.
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*
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* We also limit the number of VMOVED hops we will
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* honour, just in case someone sets up a loop.
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*/
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if (fc->flags & AFS_FS_CURSOR_VMOVED) {
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fc->ac.error = -EREMOTEIO;
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goto failed;
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}
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fc->flags |= AFS_FS_CURSOR_VMOVED;
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set_bit(AFS_VOLUME_WAIT, &vnode->volume->flags);
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set_bit(AFS_VOLUME_NEEDS_UPDATE, &vnode->volume->flags);
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fc->ac.error = afs_check_volume_status(vnode->volume, fc->key);
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if (fc->ac.error < 0)
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goto failed;
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/* If the server list didn't change, then the VLDB is
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* out of sync with the fileservers. This is hopefully
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* a temporary condition, however, so we don't want to
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* permanently block access to the file.
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*
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* TODO: Try other fileservers if we can.
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*
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* TODO: Retry a few times with sleeps.
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*/
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if (vnode->volume->servers == fc->server_list) {
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fc->ac.error = -ENOMEDIUM;
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goto failed;
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}
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goto restart_from_beginning;
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default:
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clear_bit(AFS_VOLUME_OFFLINE, &vnode->volume->flags);
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clear_bit(AFS_VOLUME_BUSY, &vnode->volume->flags);
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fc->ac.error = afs_abort_to_error(fc->ac.abort_code);
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goto failed;
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}
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case -ENETUNREACH:
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case -EHOSTUNREACH:
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case -ECONNREFUSED:
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case -ETIMEDOUT:
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case -ETIME:
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_debug("no conn");
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goto iterate_address;
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}
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restart_from_beginning:
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_debug("restart");
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afs_end_cursor(&fc->ac);
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afs_put_cb_interest(afs_v2net(vnode), fc->cbi);
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fc->cbi = NULL;
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afs_put_serverlist(afs_v2net(vnode), fc->server_list);
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fc->server_list = NULL;
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start:
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_debug("start");
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/* See if we need to do an update of the volume record. Note that the
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* volume may have moved or even have been deleted.
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*/
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fc->ac.error = afs_check_volume_status(vnode->volume, fc->key);
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if (fc->ac.error < 0)
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goto failed;
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if (!afs_start_fs_iteration(fc, vnode))
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goto failed;
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use_server:
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_debug("use");
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/* We're starting on a different fileserver from the list. We need to
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* check it, create a callback intercept, find its address list and
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* probe its capabilities before we use it.
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*/
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ASSERTCMP(fc->ac.alist, ==, NULL);
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server = fc->server_list->servers[fc->index].server;
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if (!afs_check_server_record(fc, server))
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goto failed;
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_debug("USING SERVER: %pU", &server->uuid);
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/* Make sure we've got a callback interest record for this server. We
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* have to link it in before we send the request as we can be sent a
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* break request before we've finished decoding the reply and
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* installing the vnode.
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*/
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fc->ac.error = afs_register_server_cb_interest(
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vnode, &fc->server_list->servers[fc->index]);
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if (fc->ac.error < 0)
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goto failed;
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fc->cbi = afs_get_cb_interest(vnode->cb_interest);
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read_lock(&server->fs_lock);
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alist = rcu_dereference_protected(server->addresses,
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lockdep_is_held(&server->fs_lock));
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afs_get_addrlist(alist);
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read_unlock(&server->fs_lock);
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memset(&fc->ac, 0, sizeof(fc->ac));
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/* Probe the current fileserver if we haven't done so yet. */
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if (!test_bit(AFS_SERVER_FL_PROBED, &server->flags)) {
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fc->ac.alist = afs_get_addrlist(alist);
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if (!afs_probe_fileserver(fc))
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goto failed;
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}
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if (!fc->ac.alist)
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fc->ac.alist = alist;
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else
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afs_put_addrlist(alist);
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fc->ac.start = READ_ONCE(alist->index);
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fc->ac.index = fc->ac.start;
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iterate_address:
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ASSERT(fc->ac.alist);
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_debug("iterate %d/%d", fc->ac.index, fc->ac.alist->nr_addrs);
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/* Iterate over the current server's address list to try and find an
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* address on which it will respond to us.
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*/
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if (!afs_iterate_addresses(&fc->ac))
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goto next_server;
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_leave(" = t");
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return true;
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next_server:
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_debug("next");
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afs_end_cursor(&fc->ac);
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afs_put_cb_interest(afs_v2net(vnode), fc->cbi);
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fc->cbi = NULL;
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fc->index++;
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if (fc->index >= fc->server_list->nr_servers)
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fc->index = 0;
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if (fc->index != fc->start)
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goto use_server;
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/* That's all the servers poked to no good effect. Try again if some
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* of them were busy.
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*/
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if (fc->flags & AFS_FS_CURSOR_VBUSY)
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goto restart_from_beginning;
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fc->ac.error = -EDESTADDRREQ;
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goto failed;
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failed:
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fc->flags |= AFS_FS_CURSOR_STOP;
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afs_end_cursor(&fc->ac);
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_leave(" = f [failed %d]", fc->ac.error);
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return false;
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}
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/*
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* Select the same fileserver we used for a vnode before and only that
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* fileserver. We use this when we have a lock on that file, which is backed
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* only by the fileserver we obtained it from.
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*/
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bool afs_select_current_fileserver(struct afs_fs_cursor *fc)
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{
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struct afs_vnode *vnode = fc->vnode;
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struct afs_cb_interest *cbi = vnode->cb_interest;
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struct afs_addr_list *alist;
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_enter("");
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switch (fc->ac.error) {
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case SHRT_MAX:
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if (!cbi) {
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fc->ac.error = -ESTALE;
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fc->flags |= AFS_FS_CURSOR_STOP;
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return false;
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}
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fc->cbi = afs_get_cb_interest(vnode->cb_interest);
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read_lock(&cbi->server->fs_lock);
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alist = rcu_dereference_protected(cbi->server->addresses,
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lockdep_is_held(&cbi->server->fs_lock));
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afs_get_addrlist(alist);
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read_unlock(&cbi->server->fs_lock);
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if (!alist) {
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fc->ac.error = -ESTALE;
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fc->flags |= AFS_FS_CURSOR_STOP;
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return false;
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}
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memset(&fc->ac, 0, sizeof(fc->ac));
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fc->ac.alist = alist;
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fc->ac.start = READ_ONCE(alist->index);
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fc->ac.index = fc->ac.start;
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goto iterate_address;
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case 0:
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default:
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/* Success or local failure. Stop. */
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fc->flags |= AFS_FS_CURSOR_STOP;
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_leave(" = f [okay/local %d]", fc->ac.error);
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return false;
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case -ECONNABORTED:
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fc->flags |= AFS_FS_CURSOR_STOP;
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_leave(" = f [abort]");
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return false;
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case -ENETUNREACH:
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case -EHOSTUNREACH:
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case -ECONNREFUSED:
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case -ETIMEDOUT:
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case -ETIME:
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_debug("no conn");
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goto iterate_address;
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}
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iterate_address:
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/* Iterate over the current server's address list to try and find an
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* address on which it will respond to us.
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*/
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if (afs_iterate_addresses(&fc->ac)) {
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_leave(" = t");
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return true;
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}
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afs_end_cursor(&fc->ac);
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return false;
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}
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/*
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* Tidy up a filesystem cursor and unlock the vnode.
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*/
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int afs_end_vnode_operation(struct afs_fs_cursor *fc)
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{
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struct afs_net *net = afs_v2net(fc->vnode);
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int ret;
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mutex_unlock(&fc->vnode->io_lock);
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afs_end_cursor(&fc->ac);
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afs_put_cb_interest(net, fc->cbi);
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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;
|
|
}
|