/*
* 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 <[email protected]>
* David Howells <[email protected]>
*
*/
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/circ_buf.h>
#include <linux/sched.h>
#include "internal.h"
/*
* Handle invalidation of an mmap'd file. We invalidate all the PTEs referring
* to the pages in this file's pagecache, forcing the kernel to go through
* ->fault() or ->page_mkwrite() - at which point we can handle invalidation
* more fully.
*/
void afs_invalidate_mmap_work(struct work_struct *work)
{
struct afs_vnode *vnode = container_of(work, struct afs_vnode, cb_work);
unmap_mapping_pages(vnode->netfs.inode.i_mapping, 0, 0, false);
}
static void afs_volume_init_callback(struct afs_volume *volume)
{
struct afs_vnode *vnode;
down_read(&volume->open_mmaps_lock);
list_for_each_entry(vnode, &volume->open_mmaps, cb_mmap_link) {
if (vnode->cb_v_check != atomic_read(&volume->cb_v_break)) {
atomic64_set(&vnode->cb_expires_at, AFS_NO_CB_PROMISE);
queue_work(system_unbound_wq, &vnode->cb_work);
}
}
up_read(&volume->open_mmaps_lock);
}
/*
* Allow the fileserver to request callback state (re-)initialisation.
* Unfortunately, UUIDs are not guaranteed unique.
*/
void afs_init_callback_state(struct afs_server *server)
{
struct afs_server_entry *se;
down_read(&server->cell->vs_lock);
list_for_each_entry(se, &server->volumes, slink) {
se->cb_expires_at = AFS_NO_CB_PROMISE;
se->volume->cb_expires_at = AFS_NO_CB_PROMISE;
trace_afs_cb_v_break(se->volume->vid, atomic_read(&se->volume->cb_v_break),
afs_cb_break_for_s_reinit);
if (!list_empty(&se->volume->open_mmaps))
afs_volume_init_callback(se->volume);
}
up_read(&server->cell->vs_lock);
}
/*
* 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 (atomic64_xchg(&vnode->cb_expires_at, AFS_NO_CB_PROMISE) != AFS_NO_CB_PROMISE) {
vnode->cb_break++;
vnode->cb_v_check = atomic_read(&vnode->volume->cb_v_break);
afs_clear_permits(vnode);
if (vnode->lock_state == AFS_VNODE_LOCK_WAITING_FOR_CB)
afs_lock_may_be_available(vnode);
if (reason != afs_cb_break_for_deleted &&
vnode->status.type == AFS_FTYPE_FILE &&
atomic_read(&vnode->cb_nr_mmap))
queue_work(system_unbound_wq, &vnode->cb_work);
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 = 1;
for (;;) {
/* Unfortunately, rbtree walking doesn't give reliable results
* under just the RCU read lock, so we have to check for
* changes.
*/
seq++; /* 2 on the 1st/lockless path, otherwise odd */
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;
}
if (volume && afs_try_get_volume(volume, afs_volume_trace_get_callback))
break;
if (!need_seqretry(&cell->volume_lock, seq))
break;
seq |= 1; /* Want a lock next time */
}
done_seqretry(&cell->volume_lock, seq);
return volume;
}
/*
* Allow the fileserver to break callbacks at the volume-level. This is
* typically done when, for example, a R/W volume is snapshotted to a R/O
* volume (the only way to change an R/O volume). It may also, however, happen
* when a volserver takes control of a volume (offlining it, moving it, etc.).
*
* Every file in that volume will need to be reevaluated.
*/
static void afs_break_volume_callback(struct afs_server *server,
struct afs_volume *volume)
__releases(RCU)
{
struct afs_server_list *slist = rcu_dereference(volume->servers);
unsigned int i, cb_v_break;
write_lock(&volume->cb_v_break_lock);
for (i = 0; i < slist->nr_servers; i++)
if (slist->servers[i].server == server)
slist->servers[i].cb_expires_at = AFS_NO_CB_PROMISE;
volume->cb_expires_at = AFS_NO_CB_PROMISE;
cb_v_break = atomic_inc_return_release(&volume->cb_v_break);
trace_afs_cb_v_break(volume->vid, cb_v_break, afs_cb_break_for_volume_callback);
write_unlock(&volume->cb_v_break_lock);
rcu_read_unlock();
if (!list_empty(&volume->open_mmaps))
afs_volume_init_callback(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_server *server,
struct afs_volume *volume,
struct afs_fid *fid)
{
struct super_block *sb;
struct afs_vnode *vnode;
struct inode *inode;
/* 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;
rcu_read_lock();
volume = afs_lookup_volume_rcu(server->cell, vid);
if (cbb->fid.vnode == 0 && cbb->fid.unique == 0) {
afs_break_volume_callback(server, volume);
*_count -= 1;
if (*_count)
memmove(cbb, cbb + 1, sizeof(*cbb) * *_count);
} else {
/* 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(server, volume, &cbb->fid);
} else {
*residue++ = *cbb;
}
}
rcu_read_unlock();
}
afs_put_volume(volume, afs_volume_trace_put_callback);
}
/*
* 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);
while (count > 0)
afs_break_some_callbacks(server, callbacks, &count);
}
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