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// SPDX-License-Identifier: GPL-2.0-or-later
/* Cache data I/O routines
*
* Copyright (C) 2021 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*/
#define FSCACHE_DEBUG_LEVEL OPERATION
#include <linux/fscache-cache.h>
#include <linux/uio.h>
#include <linux/bvec.h>
#include <linux/slab.h>
#include <linux/uio.h>
#include "internal.h"
/**
* fscache_wait_for_operation - Wait for an object become accessible
* @cres: The cache resources for the operation being performed
* @want_state: The minimum state the object must be at
*
* See if the target cache object is at the specified minimum state of
* accessibility yet, and if not, wait for it.
*/
bool fscache_wait_for_operation(struct netfs_cache_resources *cres,
enum fscache_want_state want_state)
{
struct fscache_cookie *cookie = fscache_cres_cookie(cres);
enum fscache_cookie_state state;
again:
if (!fscache_cache_is_live(cookie->volume->cache)) {
_leave(" [broken]");
return false;
}
state = fscache_cookie_state(cookie);
_enter("c=%08x{%u},%x", cookie->debug_id, state, want_state);
switch (state) {
case FSCACHE_COOKIE_STATE_CREATING:
case FSCACHE_COOKIE_STATE_INVALIDATING:
if (want_state == FSCACHE_WANT_PARAMS)
goto ready; /* There can be no content */
fallthrough;
case FSCACHE_COOKIE_STATE_LOOKING_UP:
case FSCACHE_COOKIE_STATE_LRU_DISCARDING:
wait_var_event(&cookie->state,
fscache_cookie_state(cookie) != state);
goto again;
case FSCACHE_COOKIE_STATE_ACTIVE:
goto ready;
case FSCACHE_COOKIE_STATE_DROPPED:
case FSCACHE_COOKIE_STATE_RELINQUISHING:
default:
_leave(" [not live]");
return false;
}
ready:
if (!cres->cache_priv2)
return cookie->volume->cache->ops->begin_operation(cres, want_state);
return true;
}
EXPORT_SYMBOL(fscache_wait_for_operation);
/*
* Begin an I/O operation on the cache, waiting till we reach the right state.
*
* Attaches the resources required to the operation resources record.
*/
static int fscache_begin_operation(struct netfs_cache_resources *cres,
struct fscache_cookie *cookie,
enum fscache_want_state want_state,
enum fscache_access_trace why)
{
enum fscache_cookie_state state;
long timeo;
bool once_only = false;
cres->ops = NULL;
cres->cache_priv = cookie;
cres->cache_priv2 = NULL;
cres->debug_id = cookie->debug_id;
cres->inval_counter = cookie->inval_counter;
if (!fscache_begin_cookie_access(cookie, why))
return -ENOBUFS;
again:
spin_lock(&cookie->lock);
state = fscache_cookie_state(cookie);
_enter("c=%08x{%u},%x", cookie->debug_id, state, want_state);
switch (state) {
case FSCACHE_COOKIE_STATE_LOOKING_UP:
case FSCACHE_COOKIE_STATE_LRU_DISCARDING:
case FSCACHE_COOKIE_STATE_INVALIDATING:
goto wait_for_file_wrangling;
case FSCACHE_COOKIE_STATE_CREATING:
if (want_state == FSCACHE_WANT_PARAMS)
goto ready; /* There can be no content */
goto wait_for_file_wrangling;
case FSCACHE_COOKIE_STATE_ACTIVE:
goto ready;
case FSCACHE_COOKIE_STATE_DROPPED:
case FSCACHE_COOKIE_STATE_RELINQUISHING:
WARN(1, "Can't use cookie in state %u\n", cookie->state);
goto not_live;
default:
goto not_live;
}
ready:
spin_unlock(&cookie->lock);
if (!cookie->volume->cache->ops->begin_operation(cres, want_state))
goto failed;
return 0;
wait_for_file_wrangling:
spin_unlock(&cookie->lock);
trace_fscache_access(cookie->debug_id, refcount_read(&cookie->ref),
atomic_read(&cookie->n_accesses),
fscache_access_io_wait);
timeo = wait_var_event_timeout(&cookie->state,
fscache_cookie_state(cookie) != state, 20 * HZ);
if (timeo <= 1 && !once_only) {
pr_warn("%s: cookie state change wait timed out: cookie->state=%u state=%u",
__func__, fscache_cookie_state(cookie), state);
fscache_print_cookie(cookie, 'O');
once_only = true;
}
goto again;
not_live:
spin_unlock(&cookie->lock);
failed:
cres->cache_priv = NULL;
cres->ops = NULL;
fscache_end_cookie_access(cookie, fscache_access_io_not_live);
_leave(" = -ENOBUFS");
return -ENOBUFS;
}
int __fscache_begin_read_operation(struct netfs_cache_resources *cres,
struct fscache_cookie *cookie)
{
return fscache_begin_operation(cres, cookie, FSCACHE_WANT_PARAMS,
fscache_access_io_read);
}
EXPORT_SYMBOL(__fscache_begin_read_operation);
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