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