// SPDX-License-Identifier: GPL-2.0-or-later
/* FS-Cache interface to CacheFiles
*
* Copyright (C) 2021 Red Hat, Inc. All Rights Reserved.
* Written by David Howells ([email protected])
*/
#include <linux/slab.h>
#include <linux/mount.h>
#include <linux/xattr.h>
#include <linux/file.h>
#include <linux/falloc.h>
#include <trace/events/fscache.h>
#include "internal.h"
static atomic_t cachefiles_object_debug_id;
/*
* Allocate a cache object record.
*/
static
struct cachefiles_object *cachefiles_alloc_object(struct fscache_cookie *cookie)
{
struct fscache_volume *vcookie = cookie->volume;
struct cachefiles_volume *volume = vcookie->cache_priv;
struct cachefiles_object *object;
_enter("{%s},%x,", vcookie->key, cookie->debug_id);
object = kmem_cache_zalloc(cachefiles_object_jar, GFP_KERNEL);
if (!object)
return NULL;
if (cachefiles_ondemand_init_obj_info(object, volume)) {
kmem_cache_free(cachefiles_object_jar, object);
return NULL;
}
refcount_set(&object->ref, 1);
spin_lock_init(&object->lock);
INIT_LIST_HEAD(&object->cache_link);
object->volume = volume;
object->debug_id = atomic_inc_return(&cachefiles_object_debug_id);
object->cookie = fscache_get_cookie(cookie, fscache_cookie_get_attach_object);
fscache_count_object(vcookie->cache);
trace_cachefiles_ref(object->debug_id, cookie->debug_id, 1,
cachefiles_obj_new);
return object;
}
/*
* Note that an object has been seen.
*/
void cachefiles_see_object(struct cachefiles_object *object,
enum cachefiles_obj_ref_trace why)
{
trace_cachefiles_ref(object->debug_id, object->cookie->debug_id,
refcount_read(&object->ref), why);
}
/*
* Increment the usage count on an object;
*/
struct cachefiles_object *cachefiles_grab_object(struct cachefiles_object *object,
enum cachefiles_obj_ref_trace why)
{
int r;
__refcount_inc(&object->ref, &r);
trace_cachefiles_ref(object->debug_id, object->cookie->debug_id, r, why);
return object;
}
/*
* dispose of a reference to an object
*/
void cachefiles_put_object(struct cachefiles_object *object,
enum cachefiles_obj_ref_trace why)
{
unsigned int object_debug_id = object->debug_id;
unsigned int cookie_debug_id = object->cookie->debug_id;
struct fscache_cache *cache;
bool done;
int r;
done = __refcount_dec_and_test(&object->ref, &r);
trace_cachefiles_ref(object_debug_id, cookie_debug_id, r, why);
if (done) {
_debug("- kill object OBJ%x", object_debug_id);
ASSERTCMP(object->file, ==, NULL);
kfree(object->d_name);
cachefiles_ondemand_deinit_obj_info(object);
cache = object->volume->cache->cache;
fscache_put_cookie(object->cookie, fscache_cookie_put_object);
object->cookie = NULL;
kmem_cache_free(cachefiles_object_jar, object);
fscache_uncount_object(cache);
}
_leave("");
}
/*
* Adjust the size of a cache file if necessary to match the DIO size. We keep
* the EOF marker a multiple of DIO blocks so that we don't fall back to doing
* non-DIO for a partial block straddling the EOF, but we also have to be
* careful of someone expanding the file and accidentally accreting the
* padding.
*/
static int cachefiles_adjust_size(struct cachefiles_object *object)
{
struct iattr newattrs;
struct file *file = object->file;
uint64_t ni_size;
loff_t oi_size;
int ret;
ni_size = object->cookie->object_size;
ni_size = round_up(ni_size, CACHEFILES_DIO_BLOCK_SIZE);
_enter("{OBJ%x},[%llu]",
object->debug_id, (unsigned long long) ni_size);
if (!file)
return -ENOBUFS;
oi_size = i_size_read(file_inode(file));
if (oi_size == ni_size)
return 0;
inode_lock(file_inode(file));
/* if there's an extension to a partial page at the end of the backing
* file, we need to discard the partial page so that we pick up new
* data after it */
if (oi_size & ~PAGE_MASK && ni_size > oi_size) {
_debug("discard tail %llx", oi_size);
newattrs.ia_valid = ATTR_SIZE;
newattrs.ia_size = oi_size & PAGE_MASK;
ret = cachefiles_inject_remove_error();
if (ret == 0)
ret = notify_change(&nop_mnt_idmap, file->f_path.dentry,
&newattrs, NULL);
if (ret < 0)
goto truncate_failed;
}
newattrs.ia_valid = ATTR_SIZE;
newattrs.ia_size = ni_size;
ret = cachefiles_inject_write_error();
if (ret == 0)
ret = notify_change(&nop_mnt_idmap, file->f_path.dentry,
&newattrs, NULL);
truncate_failed:
inode_unlock(file_inode(file));
if (ret < 0)
trace_cachefiles_io_error(NULL, file_inode(file), ret,
cachefiles_trace_notify_change_error);
if (ret == -EIO) {
cachefiles_io_error_obj(object, "Size set failed");
ret = -ENOBUFS;
}
_leave(" = %d", ret);
return ret;
}
/*
* Attempt to look up the nominated node in this cache
*/
static bool cachefiles_lookup_cookie(struct fscache_cookie *cookie)
{
struct cachefiles_object *object;
struct cachefiles_cache *cache = cookie->volume->cache->cache_priv;
const struct cred *saved_cred;
bool success;
object = cachefiles_alloc_object(cookie);
if (!object)
goto fail;
_enter("{OBJ%x}", object->debug_id);
if (!cachefiles_cook_key(object))
goto fail_put;
cookie->cache_priv = object;
cachefiles_begin_secure(cache, &saved_cred);
success = cachefiles_look_up_object(object);
if (!success)
goto fail_withdraw;
cachefiles_see_object(object, cachefiles_obj_see_lookup_cookie);
spin_lock(&cache->object_list_lock);
list_add(&object->cache_link, &cache->object_list);
spin_unlock(&cache->object_list_lock);
cachefiles_adjust_size(object);
cachefiles_end_secure(cache, saved_cred);
_leave(" = t");
return true;
fail_withdraw:
cachefiles_end_secure(cache, saved_cred);
cachefiles_see_object(object, cachefiles_obj_see_lookup_failed);
fscache_caching_failed(cookie);
_debug("failed c=%08x o=%08x", cookie->debug_id, object->debug_id);
/* The caller holds an access count on the cookie, so we need them to
* drop it before we can withdraw the object.
*/
return false;
fail_put:
cachefiles_put_object(object, cachefiles_obj_put_alloc_fail);
fail:
return false;
}
/*
* Shorten the backing object to discard any dirty data and free up
* any unused granules.
*/
static bool cachefiles_shorten_object(struct cachefiles_object *object,
struct file *file, loff_t new_size)
{
struct cachefiles_cache *cache = object->volume->cache;
struct inode *inode = file_inode(file);
loff_t i_size, dio_size;
int ret;
dio_size = round_up(new_size, CACHEFILES_DIO_BLOCK_SIZE);
i_size = i_size_read(inode);
trace_cachefiles_trunc(object, inode, i_size, dio_size,
cachefiles_trunc_shrink);
ret = cachefiles_inject_remove_error();
if (ret == 0)
ret = vfs_truncate(&file->f_path, dio_size);
if (ret < 0) {
trace_cachefiles_io_error(object, file_inode(file), ret,
cachefiles_trace_trunc_error);
cachefiles_io_error_obj(object, "Trunc-to-size failed %d", ret);
cachefiles_remove_object_xattr(cache, object, file->f_path.dentry);
return false;
}
if (new_size < dio_size) {
trace_cachefiles_trunc(object, inode, dio_size, new_size,
cachefiles_trunc_dio_adjust);
ret = cachefiles_inject_write_error();
if (ret == 0)
ret = vfs_fallocate(file, FALLOC_FL_ZERO_RANGE,
new_size, dio_size - new_size);
if (ret < 0) {
trace_cachefiles_io_error(object, file_inode(file), ret,
cachefiles_trace_fallocate_error);
cachefiles_io_error_obj(object, "Trunc-to-dio-size failed %d", ret);
cachefiles_remove_object_xattr(cache, object, file->f_path.dentry);
return false;
}
}
return true;
}
/*
* Resize the backing object.
*/
static void cachefiles_resize_cookie(struct netfs_cache_resources *cres,
loff_t new_size)
{
struct cachefiles_object *object = cachefiles_cres_object(cres);
struct cachefiles_cache *cache = object->volume->cache;
struct fscache_cookie *cookie = object->cookie;
const struct cred *saved_cred;
struct file *file = cachefiles_cres_file(cres);
loff_t old_size = cookie->object_size;
_enter("%llu->%llu", old_size, new_size);
if (new_size < old_size) {
cachefiles_begin_secure(cache, &saved_cred);
cachefiles_shorten_object(object, file, new_size);
cachefiles_end_secure(cache, saved_cred);
object->cookie->object_size = new_size;
return;
}
/* The file is being expanded. We don't need to do anything
* particularly. cookie->initial_size doesn't change and so the point
* at which we have to download before doesn't change.
*/
cookie->object_size = new_size;
}
/*
* Commit changes to the object as we drop it.
*/
static void cachefiles_commit_object(struct cachefiles_object *object,
struct cachefiles_cache *cache)
{
bool update = false;
if (test_and_clear_bit(FSCACHE_COOKIE_LOCAL_WRITE, &object->cookie->flags))
update = true;
if (test_and_clear_bit(FSCACHE_COOKIE_NEEDS_UPDATE, &object->cookie->flags))
update = true;
if (update)
cachefiles_set_object_xattr(object);
if (test_bit(CACHEFILES_OBJECT_USING_TMPFILE, &object->flags))
cachefiles_commit_tmpfile(cache, object);
}
/*
* Finalise and object and close the VFS structs that we have.
*/
static void cachefiles_clean_up_object(struct cachefiles_object *object,
struct cachefiles_cache *cache)
{
if (test_bit(FSCACHE_COOKIE_RETIRED, &object->cookie->flags)) {
if (!test_bit(CACHEFILES_OBJECT_USING_TMPFILE, &object->flags)) {
cachefiles_see_object(object, cachefiles_obj_see_clean_delete);
_debug("- inval object OBJ%x", object->debug_id);
cachefiles_delete_object(object, FSCACHE_OBJECT_WAS_RETIRED);
} else {
cachefiles_see_object(object, cachefiles_obj_see_clean_drop_tmp);
_debug("- inval object OBJ%x tmpfile", object->debug_id);
}
} else {
cachefiles_see_object(object, cachefiles_obj_see_clean_commit);
cachefiles_commit_object(object, cache);
}
cachefiles_unmark_inode_in_use(object, object->file);
if (object->file) {
fput(object->file);
object->file = NULL;
}
}
/*
* Withdraw caching for a cookie.
*/
static void cachefiles_withdraw_cookie(struct fscache_cookie *cookie)
{
struct cachefiles_object *object = cookie->cache_priv;
struct cachefiles_cache *cache = object->volume->cache;
const struct cred *saved_cred;
_enter("o=%x", object->debug_id);
cachefiles_see_object(object, cachefiles_obj_see_withdraw_cookie);
if (!list_empty(&object->cache_link)) {
spin_lock(&cache->object_list_lock);
cachefiles_see_object(object, cachefiles_obj_see_withdrawal);
list_del_init(&object->cache_link);
spin_unlock(&cache->object_list_lock);
}
cachefiles_ondemand_clean_object(object);
if (object->file) {
cachefiles_begin_secure(cache, &saved_cred);
cachefiles_clean_up_object(object, cache);
cachefiles_end_secure(cache, saved_cred);
}
cookie->cache_priv = NULL;
cachefiles_put_object(object, cachefiles_obj_put_detach);
}
/*
* Invalidate the storage associated with a cookie.
*/
static bool cachefiles_invalidate_cookie(struct fscache_cookie *cookie)
{
struct cachefiles_object *object = cookie->cache_priv;
struct file *new_file, *old_file;
bool old_tmpfile;
_enter("o=%x,[%llu]", object->debug_id, object->cookie->object_size);
old_tmpfile = test_bit(CACHEFILES_OBJECT_USING_TMPFILE, &object->flags);
if (!object->file) {
fscache_resume_after_invalidation(cookie);
_leave(" = t [light]");
return true;
}
new_file = cachefiles_create_tmpfile(object);
if (IS_ERR(new_file))
goto failed;
/* Substitute the VFS target */
_debug("sub");
spin_lock(&object->lock);
old_file = object->file;
object->file = new_file;
object->content_info = CACHEFILES_CONTENT_NO_DATA;
set_bit(CACHEFILES_OBJECT_USING_TMPFILE, &object->flags);
set_bit(FSCACHE_COOKIE_NEEDS_UPDATE, &object->cookie->flags);
spin_unlock(&object->lock);
_debug("subbed");
/* Allow I/O to take place again */
fscache_resume_after_invalidation(cookie);
if (old_file) {
if (!old_tmpfile) {
struct cachefiles_volume *volume = object->volume;
struct dentry *fan = volume->fanout[(u8)cookie->key_hash];
inode_lock_nested(d_inode(fan), I_MUTEX_PARENT);
cachefiles_bury_object(volume->cache, object, fan,
old_file->f_path.dentry,
FSCACHE_OBJECT_INVALIDATED);
}
fput(old_file);
}
_leave(" = t");
return true;
failed:
_leave(" = f");
return false;
}
const struct fscache_cache_ops cachefiles_cache_ops = {
.name = "cachefiles",
.acquire_volume = cachefiles_acquire_volume,
.free_volume = cachefiles_free_volume,
.lookup_cookie = cachefiles_lookup_cookie,
.withdraw_cookie = cachefiles_withdraw_cookie,
.invalidate_cookie = cachefiles_invalidate_cookie,
.begin_operation = cachefiles_begin_operation,
.resize_cookie = cachefiles_resize_cookie,
.prepare_to_write = cachefiles_prepare_to_write,
};
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