// 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 ([email protected])
*/
#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)) {
cres->cache_priv = NULL;
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);
int __fscache_begin_write_operation(struct netfs_cache_resources *cres,
struct fscache_cookie *cookie)
{
return fscache_begin_operation(cres, cookie, FSCACHE_WANT_PARAMS,
fscache_access_io_write);
}
EXPORT_SYMBOL(__fscache_begin_write_operation);
struct fscache_write_request {
struct netfs_cache_resources cache_resources;
struct address_space *mapping;
loff_t start;
size_t len;
bool set_bits;
bool using_pgpriv2;
netfs_io_terminated_t term_func;
void *term_func_priv;
};
void __fscache_clear_page_bits(struct address_space *mapping,
loff_t start, size_t len)
{
pgoff_t first = start / PAGE_SIZE;
pgoff_t last = (start + len - 1) / PAGE_SIZE;
struct page *page;
if (len) {
XA_STATE(xas, &mapping->i_pages, first);
rcu_read_lock();
xas_for_each(&xas, page, last) {
folio_end_private_2(page_folio(page));
}
rcu_read_unlock();
}
}
EXPORT_SYMBOL(__fscache_clear_page_bits);
/*
* Deal with the completion of writing the data to the cache.
*/
static void fscache_wreq_done(void *priv, ssize_t transferred_or_error,
bool was_async)
{
struct fscache_write_request *wreq = priv;
if (wreq->using_pgpriv2)
fscache_clear_page_bits(wreq->mapping, wreq->start, wreq->len,
wreq->set_bits);
if (wreq->term_func)
wreq->term_func(wreq->term_func_priv, transferred_or_error,
was_async);
fscache_end_operation(&wreq->cache_resources);
kfree(wreq);
}
void __fscache_write_to_cache(struct fscache_cookie *cookie,
struct address_space *mapping,
loff_t start, size_t len, loff_t i_size,
netfs_io_terminated_t term_func,
void *term_func_priv,
bool using_pgpriv2, bool cond)
{
struct fscache_write_request *wreq;
struct netfs_cache_resources *cres;
struct iov_iter iter;
int ret = -ENOBUFS;
if (len == 0)
goto abandon;
_enter("%llx,%zx", start, len);
wreq = kzalloc(sizeof(struct fscache_write_request), GFP_NOFS);
if (!wreq)
goto abandon;
wreq->mapping = mapping;
wreq->start = start;
wreq->len = len;
wreq->using_pgpriv2 = using_pgpriv2;
wreq->set_bits = cond;
wreq->term_func = term_func;
wreq->term_func_priv = term_func_priv;
cres = &wreq->cache_resources;
if (fscache_begin_operation(cres, cookie, FSCACHE_WANT_WRITE,
fscache_access_io_write) < 0)
goto abandon_free;
ret = cres->ops->prepare_write(cres, &start, &len, len, i_size, false);
if (ret < 0)
goto abandon_end;
/* TODO: Consider clearing page bits now for space the write isn't
* covering. This is more complicated than it appears when THPs are
* taken into account.
*/
iov_iter_xarray(&iter, ITER_SOURCE, &mapping->i_pages, start, len);
fscache_write(cres, start, &iter, fscache_wreq_done, wreq);
return;
abandon_end:
return fscache_wreq_done(wreq, ret, false);
abandon_free:
kfree(wreq);
abandon:
if (using_pgpriv2)
fscache_clear_page_bits(mapping, start, len, cond);
if (term_func)
term_func(term_func_priv, ret, false);
}
EXPORT_SYMBOL(__fscache_write_to_cache);
/*
* Change the size of a backing object.
*/
void __fscache_resize_cookie(struct fscache_cookie *cookie, loff_t new_size)
{
struct netfs_cache_resources cres;
trace_fscache_resize(cookie, new_size);
if (fscache_begin_operation(&cres, cookie, FSCACHE_WANT_WRITE,
fscache_access_io_resize) == 0) {
fscache_stat(&fscache_n_resizes);
set_bit(FSCACHE_COOKIE_NEEDS_UPDATE, &cookie->flags);
/* We cannot defer a resize as we need to do it inside the
* netfs's inode lock so that we're serialised with respect to
* writes.
*/
cookie->volume->cache->ops->resize_cookie(&cres, new_size);
fscache_end_operation(&cres);
} else {
fscache_stat(&fscache_n_resizes_null);
}
}
EXPORT_SYMBOL(__fscache_resize_cookie);
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