--- /dev/null
+/* AFS volume management
+ *
+ * Copyright (C) 2002, 2007 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 License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/slab.h>
+#include <linux/fs.h>
+#include <linux/pagemap.h>
+#include <linux/sched.h>
+#include "internal.h"
+
+static const char *afs_voltypes[] = { "R/W", "R/O", "BAK" };
+
+/*
+ * lookup a volume by name
+ * - this can be one of the following:
+ * "%[cell:]volume[.]" R/W volume
+ * "#[cell:]volume[.]" R/O or R/W volume (rwparent=0),
+ * or R/W (rwparent=1) volume
+ * "%[cell:]volume.readonly" R/O volume
+ * "#[cell:]volume.readonly" R/O volume
+ * "%[cell:]volume.backup" Backup volume
+ * "#[cell:]volume.backup" Backup volume
+ *
+ * The cell name is optional, and defaults to the current cell.
+ *
+ * See "The Rules of Mount Point Traversal" in Chapter 5 of the AFS SysAdmin
+ * Guide
+ * - Rule 1: Explicit type suffix forces access of that type or nothing
+ * (no suffix, then use Rule 2 & 3)
+ * - Rule 2: If parent volume is R/O, then mount R/O volume by preference, R/W
+ * if not available
+ * - Rule 3: If parent volume is R/W, then only mount R/W volume unless
+ * explicitly told otherwise
+ */
+struct afs_volume *afs_volume_lookup(struct afs_mount_params *params)
+{
+ struct afs_vlocation *vlocation = NULL;
+ struct afs_volume *volume = NULL;
+ struct afs_server *server = NULL;
+ char srvtmask;
+ int ret, loop;
+
+ _enter("{%*.*s,%d}",
+ params->volnamesz, params->volnamesz, params->volname, params->rwpath);
+
+ /* lookup the volume location record */
+ vlocation = afs_vlocation_lookup(params->cell, params->key,
+ params->volname, params->volnamesz);
+ if (IS_ERR(vlocation)) {
+ ret = PTR_ERR(vlocation);
+ vlocation = NULL;
+ goto error;
+ }
+
+ /* make the final decision on the type we want */
+ ret = -ENOMEDIUM;
+ if (params->force && !(vlocation->vldb.vidmask & (1 << params->type)))
+ goto error;
+
+ srvtmask = 0;
+ for (loop = 0; loop < vlocation->vldb.nservers; loop++)
+ srvtmask |= vlocation->vldb.srvtmask[loop];
+
+ if (params->force) {
+ if (!(srvtmask & (1 << params->type)))
+ goto error;
+ } else if (srvtmask & AFS_VOL_VTM_RO) {
+ params->type = AFSVL_ROVOL;
+ } else if (srvtmask & AFS_VOL_VTM_RW) {
+ params->type = AFSVL_RWVOL;
+ } else {
+ goto error;
+ }
+
+ down_write(¶ms->cell->vl_sem);
+
+ /* is the volume already active? */
+ if (vlocation->vols[params->type]) {
+ /* yes - re-use it */
+ volume = vlocation->vols[params->type];
+ afs_get_volume(volume);
+ goto success;
+ }
+
+ /* create a new volume record */
+ _debug("creating new volume record");
+
+ ret = -ENOMEM;
+ volume = kzalloc(sizeof(struct afs_volume), GFP_KERNEL);
+ if (!volume)
+ goto error_up;
+
+ atomic_set(&volume->usage, 1);
+ volume->type = params->type;
+ volume->type_force = params->force;
+ volume->cell = params->cell;
+ volume->vid = vlocation->vldb.vid[params->type];
+
+ ret = bdi_setup_and_register(&volume->bdi, "afs");
+ if (ret)
+ goto error_bdi;
+
+ init_rwsem(&volume->server_sem);
+
+ /* look up all the applicable server records */
+ for (loop = 0; loop < 8; loop++) {
+ if (vlocation->vldb.srvtmask[loop] & (1 << volume->type)) {
+ server = afs_lookup_server(
+ volume->cell, &vlocation->vldb.servers[loop]);
+ if (IS_ERR(server)) {
+ ret = PTR_ERR(server);
+ goto error_discard;
+ }
+
+ volume->servers[volume->nservers] = server;
+ volume->nservers++;
+ }
+ }
+
+ /* attach the cache and volume location */
+#ifdef CONFIG_AFS_FSCACHE
+ volume->cache = fscache_acquire_cookie(vlocation->cache,
+ &afs_volume_cache_index_def,
+ volume, true);
+#endif
+ afs_get_vlocation(vlocation);
+ volume->vlocation = vlocation;
+
+ vlocation->vols[volume->type] = volume;
+
+success:
+ _debug("kAFS selected %s volume %08x",
+ afs_voltypes[volume->type], volume->vid);
+ up_write(¶ms->cell->vl_sem);
+ afs_put_vlocation(vlocation);
+ _leave(" = %p", volume);
+ return volume;
+
+ /* clean up */
+error_up:
+ up_write(¶ms->cell->vl_sem);
+error:
+ afs_put_vlocation(vlocation);
+ _leave(" = %d", ret);
+ return ERR_PTR(ret);
+
+error_discard:
+ bdi_destroy(&volume->bdi);
+error_bdi:
+ up_write(¶ms->cell->vl_sem);
+
+ for (loop = volume->nservers - 1; loop >= 0; loop--)
+ afs_put_server(volume->servers[loop]);
+
+ kfree(volume);
+ goto error;
+}
+
+/*
+ * destroy a volume record
+ */
+void afs_put_volume(struct afs_volume *volume)
+{
+ struct afs_vlocation *vlocation;
+ int loop;
+
+ if (!volume)
+ return;
+
+ _enter("%p", volume);
+
+ ASSERTCMP(atomic_read(&volume->usage), >, 0);
+
+ vlocation = volume->vlocation;
+
+ /* to prevent a race, the decrement and the dequeue must be effectively
+ * atomic */
+ down_write(&vlocation->cell->vl_sem);
+
+ if (likely(!atomic_dec_and_test(&volume->usage))) {
+ up_write(&vlocation->cell->vl_sem);
+ _leave("");
+ return;
+ }
+
+ vlocation->vols[volume->type] = NULL;
+
+ up_write(&vlocation->cell->vl_sem);
+
+ /* finish cleaning up the volume */
+#ifdef CONFIG_AFS_FSCACHE
+ fscache_relinquish_cookie(volume->cache, 0);
+#endif
+ afs_put_vlocation(vlocation);
+
+ for (loop = volume->nservers - 1; loop >= 0; loop--)
+ afs_put_server(volume->servers[loop]);
+
+ bdi_destroy(&volume->bdi);
+ kfree(volume);
+
+ _leave(" [destroyed]");
+}
+
+/*
+ * pick a server to use to try accessing this volume
+ * - returns with an elevated usage count on the server chosen
+ */
+struct afs_server *afs_volume_pick_fileserver(struct afs_vnode *vnode)
+{
+ struct afs_volume *volume = vnode->volume;
+ struct afs_server *server;
+ int ret, state, loop;
+
+ _enter("%s", volume->vlocation->vldb.name);
+
+ /* stick with the server we're already using if we can */
+ if (vnode->server && vnode->server->fs_state == 0) {
+ afs_get_server(vnode->server);
+ _leave(" = %p [current]", vnode->server);
+ return vnode->server;
+ }
+
+ down_read(&volume->server_sem);
+
+ /* handle the no-server case */
+ if (volume->nservers == 0) {
+ ret = volume->rjservers ? -ENOMEDIUM : -ESTALE;
+ up_read(&volume->server_sem);
+ _leave(" = %d [no servers]", ret);
+ return ERR_PTR(ret);
+ }
+
+ /* basically, just search the list for the first live server and use
+ * that */
+ ret = 0;
+ for (loop = 0; loop < volume->nservers; loop++) {
+ server = volume->servers[loop];
+ state = server->fs_state;
+
+ _debug("consider %d [%d]", loop, state);
+
+ switch (state) {
+ /* found an apparently healthy server */
+ case 0:
+ afs_get_server(server);
+ up_read(&volume->server_sem);
+ _leave(" = %p (picked %08x)",
+ server, ntohl(server->addr.s_addr));
+ return server;
+
+ case -ENETUNREACH:
+ if (ret == 0)
+ ret = state;
+ break;
+
+ case -EHOSTUNREACH:
+ if (ret == 0 ||
+ ret == -ENETUNREACH)
+ ret = state;
+ break;
+
+ case -ECONNREFUSED:
+ if (ret == 0 ||
+ ret == -ENETUNREACH ||
+ ret == -EHOSTUNREACH)
+ ret = state;
+ break;
+
+ default:
+ case -EREMOTEIO:
+ if (ret == 0 ||
+ ret == -ENETUNREACH ||
+ ret == -EHOSTUNREACH ||
+ ret == -ECONNREFUSED)
+ ret = state;
+ break;
+ }
+ }
+
+ /* no available servers
+ * - TODO: handle the no active servers case better
+ */
+ up_read(&volume->server_sem);
+ _leave(" = %d", ret);
+ return ERR_PTR(ret);
+}
+
+/*
+ * release a server after use
+ * - releases the ref on the server struct that was acquired by picking
+ * - records result of using a particular server to access a volume
+ * - return 0 to try again, 1 if okay or to issue error
+ * - the caller must release the server struct if result was 0
+ */
+int afs_volume_release_fileserver(struct afs_vnode *vnode,
+ struct afs_server *server,
+ int result)
+{
+ struct afs_volume *volume = vnode->volume;
+ unsigned loop;
+
+ _enter("%s,%08x,%d",
+ volume->vlocation->vldb.name, ntohl(server->addr.s_addr),
+ result);
+
+ switch (result) {
+ /* success */
+ case 0:
+ server->fs_act_jif = jiffies;
+ server->fs_state = 0;
+ _leave("");
+ return 1;
+
+ /* the fileserver denied all knowledge of the volume */
+ case -ENOMEDIUM:
+ server->fs_act_jif = jiffies;
+ down_write(&volume->server_sem);
+
+ /* firstly, find where the server is in the active list (if it
+ * is) */
+ for (loop = 0; loop < volume->nservers; loop++)
+ if (volume->servers[loop] == server)
+ goto present;
+
+ /* no longer there - may have been discarded by another op */
+ goto try_next_server_upw;
+
+ present:
+ volume->nservers--;
+ memmove(&volume->servers[loop],
+ &volume->servers[loop + 1],
+ sizeof(volume->servers[loop]) *
+ (volume->nservers - loop));
+ volume->servers[volume->nservers] = NULL;
+ afs_put_server(server);
+ volume->rjservers++;
+
+ if (volume->nservers > 0)
+ /* another server might acknowledge its existence */
+ goto try_next_server_upw;
+
+ /* handle the case where all the fileservers have rejected the
+ * volume
+ * - TODO: try asking the fileservers for volume information
+ * - TODO: contact the VL server again to see if the volume is
+ * no longer registered
+ */
+ up_write(&volume->server_sem);
+ afs_put_server(server);
+ _leave(" [completely rejected]");
+ return 1;
+
+ /* problem reaching the server */
+ case -ENETUNREACH:
+ case -EHOSTUNREACH:
+ case -ECONNREFUSED:
+ case -ETIME:
+ case -ETIMEDOUT:
+ case -EREMOTEIO:
+ /* mark the server as dead
+ * TODO: vary dead timeout depending on error
+ */
+ spin_lock(&server->fs_lock);
+ if (!server->fs_state) {
+ server->fs_dead_jif = jiffies + HZ * 10;
+ server->fs_state = result;
+ printk("kAFS: SERVER DEAD state=%d\n", result);
+ }
+ spin_unlock(&server->fs_lock);
+ goto try_next_server;
+
+ /* miscellaneous error */
+ default:
+ server->fs_act_jif = jiffies;
+ case -ENOMEM:
+ case -ENONET:
+ /* tell the caller to accept the result */
+ afs_put_server(server);
+ _leave(" [local failure]");
+ return 1;
+ }
+
+ /* tell the caller to loop around and try the next server */
+try_next_server_upw:
+ up_write(&volume->server_sem);
+try_next_server:
+ afs_put_server(server);
+ _leave(" [try next server]");
+ return 0;
+}
Code Review / kvmfornfv.git / blobdiff