linux/fs/afs/volume.c
David Howells 523d27cda1 afs: Convert afs to use the new fscache API
Change the afs filesystem to support the new afs driver.

The following changes have been made:

 (1) The fscache_netfs struct is no more, and there's no need to register
     the filesystem as a whole.  There's also no longer a cell cookie.

 (2) The volume cookie is now an fscache_volume cookie, allocated with
     fscache_acquire_volume().  This function takes three parameters: a
     string representing the "volume" in the index, a string naming the
     cache to use (or NULL) and a u64 that conveys coherency metadata for
     the volume.

     For afs, I've made it render the volume name string as:

        "afs,<cell>,<volume_id>"

     and the coherency data is currently 0.

 (3) The fscache_cookie_def is no more and needed information is passed
     directly to fscache_acquire_cookie().  The cache no longer calls back
     into the filesystem, but rather metadata changes are indicated at
     other times.

     fscache_acquire_cookie() is passed the same keying and coherency
     information as before, except that these are now stored in big endian
     form instead of cpu endian.  This makes the cache more copyable.

 (4) fscache_use_cookie() and fscache_unuse_cookie() are called when a file
     is opened or closed to prevent a cache file from being culled and to
     keep resources to hand that are needed to do I/O.

     fscache_use_cookie() is given an indication if the cache is likely to
     be modified locally (e.g. the file is open for writing).

     fscache_unuse_cookie() is given a coherency update if we had the file
     open for writing and will update that.

 (5) fscache_invalidate() is now given uptodate auxiliary data and a file
     size.  It can also take a flag to indicate if this was due to a DIO
     write.  This is wrapped into afs_fscache_invalidate() now for
     convenience.

 (6) fscache_resize() now gets called from the finalisation of
     afs_setattr(), and afs_setattr() does use/unuse of the cookie around
     the call to support this.

 (7) fscache_note_page_release() is called from afs_release_page().

 (8) Use a killable wait in nfs_vm_page_mkwrite() when waiting for
     PG_fscache to be cleared.

Render the parts of the cookie key for an afs inode cookie as big endian.

Changes
=======
ver #2:
 - Use gfpflags_allow_blocking() rather than using flag directly.
 - fscache_acquire_volume() now returns errors.

Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Jeff Layton <jlayton@kernel.org>
Tested-by: kafs-testing@auristor.com
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org
cc: linux-cachefs@redhat.com
Link: https://lore.kernel.org/r/163819661382.215744.1485608824741611837.stgit@warthog.procyon.org.uk/ # v1
Link: https://lore.kernel.org/r/163906970002.143852.17678518584089878259.stgit@warthog.procyon.org.uk/ # v2
Link: https://lore.kernel.org/r/163967174665.1823006.1301789965454084220.stgit@warthog.procyon.org.uk/ # v3
Link: https://lore.kernel.org/r/164021568841.640689.6684240152253400380.stgit@warthog.procyon.org.uk/ # v4
2022-01-07 13:44:47 +00:00

429 lines
11 KiB
C

// SPDX-License-Identifier: GPL-2.0-or-later
/* AFS volume management
*
* Copyright (C) 2002, 2007 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*/
#include <linux/kernel.h>
#include <linux/slab.h>
#include "internal.h"
unsigned __read_mostly afs_volume_gc_delay = 10;
unsigned __read_mostly afs_volume_record_life = 60 * 60;
/*
* Insert a volume into a cell. If there's an existing volume record, that is
* returned instead with a ref held.
*/
static struct afs_volume *afs_insert_volume_into_cell(struct afs_cell *cell,
struct afs_volume *volume)
{
struct afs_volume *p;
struct rb_node *parent = NULL, **pp;
write_seqlock(&cell->volume_lock);
pp = &cell->volumes.rb_node;
while (*pp) {
parent = *pp;
p = rb_entry(parent, struct afs_volume, cell_node);
if (p->vid < volume->vid) {
pp = &(*pp)->rb_left;
} else if (p->vid > volume->vid) {
pp = &(*pp)->rb_right;
} else {
volume = afs_get_volume(p, afs_volume_trace_get_cell_insert);
goto found;
}
}
rb_link_node_rcu(&volume->cell_node, parent, pp);
rb_insert_color(&volume->cell_node, &cell->volumes);
hlist_add_head_rcu(&volume->proc_link, &cell->proc_volumes);
found:
write_sequnlock(&cell->volume_lock);
return volume;
}
static void afs_remove_volume_from_cell(struct afs_volume *volume)
{
struct afs_cell *cell = volume->cell;
if (!hlist_unhashed(&volume->proc_link)) {
trace_afs_volume(volume->vid, atomic_read(&volume->usage),
afs_volume_trace_remove);
write_seqlock(&cell->volume_lock);
hlist_del_rcu(&volume->proc_link);
rb_erase(&volume->cell_node, &cell->volumes);
write_sequnlock(&cell->volume_lock);
}
}
/*
* Allocate a volume record and load it up from a vldb record.
*/
static struct afs_volume *afs_alloc_volume(struct afs_fs_context *params,
struct afs_vldb_entry *vldb,
unsigned long type_mask)
{
struct afs_server_list *slist;
struct afs_volume *volume;
int ret = -ENOMEM, nr_servers = 0, i;
for (i = 0; i < vldb->nr_servers; i++)
if (vldb->fs_mask[i] & type_mask)
nr_servers++;
volume = kzalloc(sizeof(struct afs_volume), GFP_KERNEL);
if (!volume)
goto error_0;
volume->vid = vldb->vid[params->type];
volume->update_at = ktime_get_real_seconds() + afs_volume_record_life;
volume->cell = afs_get_cell(params->cell, afs_cell_trace_get_vol);
volume->type = params->type;
volume->type_force = params->force;
volume->name_len = vldb->name_len;
atomic_set(&volume->usage, 1);
INIT_HLIST_NODE(&volume->proc_link);
rwlock_init(&volume->servers_lock);
rwlock_init(&volume->cb_v_break_lock);
memcpy(volume->name, vldb->name, vldb->name_len + 1);
slist = afs_alloc_server_list(params->cell, params->key, vldb, type_mask);
if (IS_ERR(slist)) {
ret = PTR_ERR(slist);
goto error_1;
}
refcount_set(&slist->usage, 1);
rcu_assign_pointer(volume->servers, slist);
trace_afs_volume(volume->vid, 1, afs_volume_trace_alloc);
return volume;
error_1:
afs_put_cell(volume->cell, afs_cell_trace_put_vol);
kfree(volume);
error_0:
return ERR_PTR(ret);
}
/*
* Look up or allocate a volume record.
*/
static struct afs_volume *afs_lookup_volume(struct afs_fs_context *params,
struct afs_vldb_entry *vldb,
unsigned long type_mask)
{
struct afs_volume *candidate, *volume;
candidate = afs_alloc_volume(params, vldb, type_mask);
if (IS_ERR(candidate))
return candidate;
volume = afs_insert_volume_into_cell(params->cell, candidate);
if (volume != candidate)
afs_put_volume(params->net, candidate, afs_volume_trace_put_cell_dup);
return volume;
}
/*
* Look up a VLDB record for a volume.
*/
static struct afs_vldb_entry *afs_vl_lookup_vldb(struct afs_cell *cell,
struct key *key,
const char *volname,
size_t volnamesz)
{
struct afs_vldb_entry *vldb = ERR_PTR(-EDESTADDRREQ);
struct afs_vl_cursor vc;
int ret;
if (!afs_begin_vlserver_operation(&vc, cell, key))
return ERR_PTR(-ERESTARTSYS);
while (afs_select_vlserver(&vc)) {
vldb = afs_vl_get_entry_by_name_u(&vc, volname, volnamesz);
}
ret = afs_end_vlserver_operation(&vc);
return ret < 0 ? ERR_PTR(ret) : vldb;
}
/*
* Look up a volume in the VL server and create a candidate volume record for
* it.
*
* The volume name 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_create_volume(struct afs_fs_context *params)
{
struct afs_vldb_entry *vldb;
struct afs_volume *volume;
unsigned long type_mask = 1UL << params->type;
vldb = afs_vl_lookup_vldb(params->cell, params->key,
params->volname, params->volnamesz);
if (IS_ERR(vldb))
return ERR_CAST(vldb);
if (test_bit(AFS_VLDB_QUERY_ERROR, &vldb->flags)) {
volume = ERR_PTR(vldb->error);
goto error;
}
/* Make the final decision on the type we want */
volume = ERR_PTR(-ENOMEDIUM);
if (params->force) {
if (!(vldb->flags & type_mask))
goto error;
} else if (test_bit(AFS_VLDB_HAS_RO, &vldb->flags)) {
params->type = AFSVL_ROVOL;
} else if (test_bit(AFS_VLDB_HAS_RW, &vldb->flags)) {
params->type = AFSVL_RWVOL;
} else {
goto error;
}
type_mask = 1UL << params->type;
volume = afs_lookup_volume(params, vldb, type_mask);
error:
kfree(vldb);
return volume;
}
/*
* Destroy a volume record
*/
static void afs_destroy_volume(struct afs_net *net, struct afs_volume *volume)
{
_enter("%p", volume);
#ifdef CONFIG_AFS_FSCACHE
ASSERTCMP(volume->cache, ==, NULL);
#endif
afs_remove_volume_from_cell(volume);
afs_put_serverlist(net, rcu_access_pointer(volume->servers));
afs_put_cell(volume->cell, afs_cell_trace_put_vol);
trace_afs_volume(volume->vid, atomic_read(&volume->usage),
afs_volume_trace_free);
kfree_rcu(volume, rcu);
_leave(" [destroyed]");
}
/*
* Get a reference on a volume record.
*/
struct afs_volume *afs_get_volume(struct afs_volume *volume,
enum afs_volume_trace reason)
{
if (volume) {
int u = atomic_inc_return(&volume->usage);
trace_afs_volume(volume->vid, u, reason);
}
return volume;
}
/*
* Drop a reference on a volume record.
*/
void afs_put_volume(struct afs_net *net, struct afs_volume *volume,
enum afs_volume_trace reason)
{
if (volume) {
afs_volid_t vid = volume->vid;
int u = atomic_dec_return(&volume->usage);
trace_afs_volume(vid, u, reason);
if (u == 0)
afs_destroy_volume(net, volume);
}
}
/*
* Activate a volume.
*/
int afs_activate_volume(struct afs_volume *volume)
{
#ifdef CONFIG_AFS_FSCACHE
struct fscache_volume *vcookie;
char *name;
name = kasprintf(GFP_KERNEL, "afs,%s,%llx",
volume->cell->name, volume->vid);
if (!name)
return -ENOMEM;
vcookie = fscache_acquire_volume(name, NULL, NULL, 0);
if (IS_ERR(vcookie)) {
if (vcookie != ERR_PTR(-EBUSY)) {
kfree(name);
return PTR_ERR(vcookie);
}
pr_err("AFS: Cache volume key already in use (%s)\n", name);
vcookie = NULL;
}
volume->cache = vcookie;
kfree(name);
#endif
return 0;
}
/*
* Deactivate a volume.
*/
void afs_deactivate_volume(struct afs_volume *volume)
{
_enter("%s", volume->name);
#ifdef CONFIG_AFS_FSCACHE
fscache_relinquish_volume(volume->cache, NULL,
test_bit(AFS_VOLUME_DELETED, &volume->flags));
volume->cache = NULL;
#endif
_leave("");
}
/*
* Query the VL service to update the volume status.
*/
static int afs_update_volume_status(struct afs_volume *volume, struct key *key)
{
struct afs_server_list *new, *old, *discard;
struct afs_vldb_entry *vldb;
char idbuf[16];
int ret, idsz;
_enter("");
/* We look up an ID by passing it as a decimal string in the
* operation's name parameter.
*/
idsz = sprintf(idbuf, "%llu", volume->vid);
vldb = afs_vl_lookup_vldb(volume->cell, key, idbuf, idsz);
if (IS_ERR(vldb)) {
ret = PTR_ERR(vldb);
goto error;
}
/* See if the volume got renamed. */
if (vldb->name_len != volume->name_len ||
memcmp(vldb->name, volume->name, vldb->name_len) != 0) {
/* TODO: Use RCU'd string. */
memcpy(volume->name, vldb->name, AFS_MAXVOLNAME);
volume->name_len = vldb->name_len;
}
/* See if the volume's server list got updated. */
new = afs_alloc_server_list(volume->cell, key,
vldb, (1 << volume->type));
if (IS_ERR(new)) {
ret = PTR_ERR(new);
goto error_vldb;
}
write_lock(&volume->servers_lock);
discard = new;
old = rcu_dereference_protected(volume->servers,
lockdep_is_held(&volume->servers_lock));
if (afs_annotate_server_list(new, old)) {
new->seq = volume->servers_seq + 1;
rcu_assign_pointer(volume->servers, new);
smp_wmb();
volume->servers_seq++;
discard = old;
}
volume->update_at = ktime_get_real_seconds() + afs_volume_record_life;
write_unlock(&volume->servers_lock);
ret = 0;
afs_put_serverlist(volume->cell->net, discard);
error_vldb:
kfree(vldb);
error:
_leave(" = %d", ret);
return ret;
}
/*
* Make sure the volume record is up to date.
*/
int afs_check_volume_status(struct afs_volume *volume, struct afs_operation *op)
{
int ret, retries = 0;
_enter("");
retry:
if (test_bit(AFS_VOLUME_WAIT, &volume->flags))
goto wait;
if (volume->update_at <= ktime_get_real_seconds() ||
test_bit(AFS_VOLUME_NEEDS_UPDATE, &volume->flags))
goto update;
_leave(" = 0");
return 0;
update:
if (!test_and_set_bit_lock(AFS_VOLUME_UPDATING, &volume->flags)) {
clear_bit(AFS_VOLUME_NEEDS_UPDATE, &volume->flags);
ret = afs_update_volume_status(volume, op->key);
if (ret < 0)
set_bit(AFS_VOLUME_NEEDS_UPDATE, &volume->flags);
clear_bit_unlock(AFS_VOLUME_WAIT, &volume->flags);
clear_bit_unlock(AFS_VOLUME_UPDATING, &volume->flags);
wake_up_bit(&volume->flags, AFS_VOLUME_WAIT);
_leave(" = %d", ret);
return ret;
}
wait:
if (!test_bit(AFS_VOLUME_WAIT, &volume->flags)) {
_leave(" = 0 [no wait]");
return 0;
}
ret = wait_on_bit(&volume->flags, AFS_VOLUME_WAIT,
(op->flags & AFS_OPERATION_UNINTR) ?
TASK_UNINTERRUPTIBLE : TASK_INTERRUPTIBLE);
if (ret == -ERESTARTSYS) {
_leave(" = %d", ret);
return ret;
}
retries++;
if (retries == 4) {
_leave(" = -ESTALE");
return -ESTALE;
}
goto retry;
}