diff options
Diffstat (limited to 'fs/afs/rotate.c')
| -rw-r--r-- | fs/afs/rotate.c | 715 |
1 files changed, 715 insertions, 0 deletions
diff --git a/fs/afs/rotate.c b/fs/afs/rotate.c new file mode 100644 index 000000000000..e728ca1776c9 --- /dev/null +++ b/fs/afs/rotate.c @@ -0,0 +1,715 @@ +/* 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. + */ +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 (test_bit(AFS_VNODE_READLOCKED, &vnode->flags) || + test_bit(AFS_VNODE_WRITELOCKED, &vnode->flags)) + 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 failed; + } + + 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 failed; + } + + /* 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; + } + +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; + goto use_server; + +next_server: + _debug("next"); + 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; + +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->servers[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); + + + /* 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)) + goto failed; + } + + if (!fc->ac.alist) + fc->ac.alist = alist; + else + afs_put_addrlist(alist); + + fc->ac.addr = NULL; + fc->ac.start = READ_ONCE(alist->index); + fc->ac.index = fc->ac.start; + fc->ac.error = 0; + fc->ac.begun = false; + goto iterate_address; + +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)) { + _leave(" = t"); + return true; + } + + afs_end_cursor(&fc->ac); + goto next_server; + +failed: + fc->flags |= AFS_FS_CURSOR_STOP; + _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(""); + + if (!cbi) { + fc->ac.error = -ESTALE; + fc->flags |= AFS_FS_CURSOR_STOP; + return false; + } + + read_lock(&cbi->server->fs_lock); + alist = afs_get_addrlist(cbi->server->addresses); + read_unlock(&cbi->server->fs_lock); + if (!alist) { + fc->ac.error = -ESTALE; + fc->flags |= AFS_FS_CURSOR_STOP; + return false; + } + + fc->ac.alist = alist; + fc->ac.error = 0; + return true; +} + +/* + * 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; +} + +#if 0 +/* + * Set a filesystem server cursor for using a specific FS server. + */ +int afs_set_fs_cursor(struct afs_fs_cursor *fc, struct afs_vnode *vnode) +{ + afs_init_fs_cursor(fc, vnode); + + read_seqlock_excl(&vnode->cb_lock); + if (vnode->cb_interest) { + if (vnode->cb_interest->server->fs_state == 0) + fc->server = afs_get_server(vnode->cb_interest->server); + else + fc->ac.error = vnode->cb_interest->server->fs_state; + } else { + fc->ac.error = -ESTALE; + } + read_sequnlock_excl(&vnode->cb_lock); + + return fc->ac.error; +} + +/* + * pick a server to use to try accessing this volume + * - returns with an elevated usage count on the server chosen + */ +bool afs_volume_pick_fileserver(struct afs_fs_cursor *fc, 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->cb_interest && vnode->cb_interest->server->fs_state == 0) { + fc->server = afs_get_server(vnode->cb_interest->server); + goto set_server; + } + + down_read(&volume->server_sem); + + /* handle the no-server case */ + if (volume->nservers == 0) { + fc->ac.error = volume->rjservers ? -ENOMEDIUM : -ESTALE; + up_read(&volume->server_sem); + _leave(" = f [no servers %d]", fc->ac.error); + return false; + } + + /* 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) { + case 0: + goto picked_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; + } + } + +error: + fc->ac.error = ret; + + /* no available servers + * - TODO: handle the no active servers case better + */ + up_read(&volume->server_sem); + _leave(" = f [%d]", fc->ac.error); + return false; + +picked_server: + /* Found an apparently healthy server. We need to register an interest + * in receiving callbacks before we talk to it. + */ + ret = afs_register_server_cb_interest(vnode, + &volume->cb_interests[loop], server); + if (ret < 0) + goto error; + + fc->server = afs_get_server(server); + up_read(&volume->server_sem); +set_server: + fc->ac.alist = afs_get_addrlist(fc->server->addrs); + fc->ac.addr = &fc->ac.alist->addrs[0]; + _debug("USING SERVER: %pIS\n", &fc->ac.addr->transport); + _leave(" = t (picked %pIS)", &fc->ac.addr->transport); + return true; +} + +/* + * 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 true to try again, false if okay or to issue error + * - the caller must release the server struct if result was false + */ +bool afs_iterate_fs_cursor(struct afs_fs_cursor *fc, + struct afs_vnode *vnode) +{ + struct afs_volume *volume = vnode->volume; + struct afs_server *server = fc->server; + unsigned loop; + + _enter("%s,%pIS,%d", + volume->vlocation->vldb.name, &fc->ac.addr->transport, + fc->ac.error); + + switch (fc->ac.error) { + /* success */ + case 0: + server->fs_state = 0; + _leave(" = f"); + return false; + + /* the fileserver denied all knowledge of the volume */ + case -ENOMEDIUM: + 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(afs_v2net(vnode), 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(afs_v2net(vnode), server); + fc->server = NULL; + _leave(" = f [completely rejected]"); + return false; + + /* 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_state = fc->ac.error; + printk("kAFS: SERVER DEAD state=%d\n", fc->ac.error); + } + spin_unlock(&server->fs_lock); + goto try_next_server; + + /* miscellaneous error */ + default: + case -ENOMEM: + case -ENONET: + /* tell the caller to accept the result */ + afs_put_server(afs_v2net(vnode), server); + fc->server = NULL; + _leave(" = f [local failure]"); + return false; + } + + /* 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(afs_v2net(vnode), server); + _leave(" = t [try next server]"); + return true; +} + +/* + * Clean up a fileserver cursor. + */ +int afs_end_fs_cursor(struct afs_fs_cursor *fc, struct afs_net *net) +{ + afs_end_cursor(&fc->ac); + afs_put_server(net, fc->server); + return fc->ac.error; +} + +#endif |