/* 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; }