/*
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* Copyright (c) 2002, 2007 Red Hat, Inc. All rights reserved.
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*
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* This software may be freely redistributed under the terms of the
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* GNU General Public License.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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*
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* Authors: David Woodhouse <dwmw2@infradead.org>
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* David Howells <dhowells@redhat.com>
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*
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*/
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/init.h>
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#include <linux/circ_buf.h>
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#include <linux/sched.h>
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#include "internal.h"
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/*
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* Allow the fileserver to request callback state (re-)initialisation.
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* Unfortunately, UUIDs are not guaranteed unique.
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*/
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void afs_init_callback_state(struct afs_server *server)
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{
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rcu_read_lock();
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do {
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server->cb_s_break++;
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server = rcu_dereference(server->uuid_next);
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} while (0);
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rcu_read_unlock();
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}
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/*
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* actually break a callback
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*/
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void __afs_break_callback(struct afs_vnode *vnode, enum afs_cb_break_reason reason)
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{
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_enter("");
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clear_bit(AFS_VNODE_NEW_CONTENT, &vnode->flags);
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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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afs_clear_permits(vnode);
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if (vnode->lock_state == AFS_VNODE_LOCK_WAITING_FOR_CB)
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afs_lock_may_be_available(vnode);
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trace_afs_cb_break(&vnode->fid, vnode->cb_break, reason, true);
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} else {
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trace_afs_cb_break(&vnode->fid, vnode->cb_break, reason, false);
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}
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}
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void afs_break_callback(struct afs_vnode *vnode, enum afs_cb_break_reason reason)
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{
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write_seqlock(&vnode->cb_lock);
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__afs_break_callback(vnode, reason);
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write_sequnlock(&vnode->cb_lock);
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}
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/*
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* Look up a volume by volume ID under RCU conditions.
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*/
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static struct afs_volume *afs_lookup_volume_rcu(struct afs_cell *cell,
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afs_volid_t vid)
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{
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struct afs_volume *volume = NULL;
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struct rb_node *p;
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int seq = 0;
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do {
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/* Unfortunately, rbtree walking doesn't give reliable results
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* under just the RCU read lock, so we have to check for
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* changes.
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*/
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read_seqbegin_or_lock(&cell->volume_lock, &seq);
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p = rcu_dereference_raw(cell->volumes.rb_node);
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while (p) {
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volume = rb_entry(p, struct afs_volume, cell_node);
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if (volume->vid < vid)
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p = rcu_dereference_raw(p->rb_left);
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else if (volume->vid > vid)
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p = rcu_dereference_raw(p->rb_right);
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else
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break;
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volume = NULL;
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}
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} while (need_seqretry(&cell->volume_lock, seq));
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done_seqretry(&cell->volume_lock, seq);
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return volume;
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}
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/*
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* allow the fileserver to explicitly break one callback
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* - happens when
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* - the backing file is changed
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* - a lock is released
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*/
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static void afs_break_one_callback(struct afs_volume *volume,
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struct afs_fid *fid)
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{
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struct super_block *sb;
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struct afs_vnode *vnode;
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struct inode *inode;
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if (fid->vnode == 0 && fid->unique == 0) {
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/* The callback break applies to an entire volume. */
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write_lock(&volume->cb_v_break_lock);
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volume->cb_v_break++;
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trace_afs_cb_break(fid, volume->cb_v_break,
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afs_cb_break_for_volume_callback, false);
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write_unlock(&volume->cb_v_break_lock);
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return;
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}
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/* See if we can find a matching inode - even an I_NEW inode needs to
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* be marked as it can have its callback broken before we finish
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* setting up the local inode.
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*/
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sb = rcu_dereference(volume->sb);
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if (!sb)
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return;
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inode = find_inode_rcu(sb, fid->vnode, afs_ilookup5_test_by_fid, fid);
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if (inode) {
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vnode = AFS_FS_I(inode);
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afs_break_callback(vnode, afs_cb_break_for_callback);
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} else {
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trace_afs_cb_miss(fid, afs_cb_break_for_callback);
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}
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}
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static void afs_break_some_callbacks(struct afs_server *server,
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struct afs_callback_break *cbb,
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size_t *_count)
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{
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struct afs_callback_break *residue = cbb;
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struct afs_volume *volume;
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afs_volid_t vid = cbb->fid.vid;
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size_t i;
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volume = afs_lookup_volume_rcu(server->cell, vid);
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/* TODO: Find all matching volumes if we couldn't match the server and
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* break them anyway.
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*/
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for (i = *_count; i > 0; cbb++, i--) {
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if (cbb->fid.vid == vid) {
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_debug("- Fid { vl=%08llx n=%llu u=%u }",
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cbb->fid.vid,
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cbb->fid.vnode,
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cbb->fid.unique);
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--*_count;
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if (volume)
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afs_break_one_callback(volume, &cbb->fid);
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} else {
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*residue++ = *cbb;
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}
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}
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}
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/*
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* allow the fileserver to break callback promises
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*/
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void afs_break_callbacks(struct afs_server *server, size_t count,
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struct afs_callback_break *callbacks)
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{
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_enter("%p,%zu,", server, count);
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ASSERT(server != NULL);
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rcu_read_lock();
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while (count > 0)
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afs_break_some_callbacks(server, callbacks, &count);
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rcu_read_unlock();
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return;
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}
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