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![Jeffle Xu](/assets/img/avatar_default.png)
Enable on-demand read mode by adding an optional parameter to the "bind" command. On-demand mode will be turned on when this parameter is "ondemand", i.e. "bind ondemand". Otherwise cachefiles will work in the original mode. Signed-off-by: Jeffle Xu <jefflexu@linux.alibaba.com> Link: https://lore.kernel.org/r/20220509074028.74954-7-jefflexu@linux.alibaba.com Acked-by: David Howells <dhowells@redhat.com> Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
814 lines
18 KiB
C
814 lines
18 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/* Daemon interface
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*
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* Copyright (C) 2007, 2021 Red Hat, Inc. All Rights Reserved.
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* Written by David Howells (dhowells@redhat.com)
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*/
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#include <linux/module.h>
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#include <linux/init.h>
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#include <linux/sched.h>
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#include <linux/completion.h>
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#include <linux/slab.h>
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#include <linux/fs.h>
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#include <linux/file.h>
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#include <linux/namei.h>
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#include <linux/poll.h>
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#include <linux/mount.h>
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#include <linux/statfs.h>
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#include <linux/ctype.h>
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#include <linux/string.h>
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#include <linux/fs_struct.h>
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#include "internal.h"
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static int cachefiles_daemon_open(struct inode *, struct file *);
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static int cachefiles_daemon_release(struct inode *, struct file *);
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static ssize_t cachefiles_daemon_read(struct file *, char __user *, size_t,
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loff_t *);
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static ssize_t cachefiles_daemon_write(struct file *, const char __user *,
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size_t, loff_t *);
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static __poll_t cachefiles_daemon_poll(struct file *,
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struct poll_table_struct *);
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static int cachefiles_daemon_frun(struct cachefiles_cache *, char *);
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static int cachefiles_daemon_fcull(struct cachefiles_cache *, char *);
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static int cachefiles_daemon_fstop(struct cachefiles_cache *, char *);
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static int cachefiles_daemon_brun(struct cachefiles_cache *, char *);
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static int cachefiles_daemon_bcull(struct cachefiles_cache *, char *);
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static int cachefiles_daemon_bstop(struct cachefiles_cache *, char *);
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static int cachefiles_daemon_cull(struct cachefiles_cache *, char *);
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static int cachefiles_daemon_debug(struct cachefiles_cache *, char *);
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static int cachefiles_daemon_dir(struct cachefiles_cache *, char *);
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static int cachefiles_daemon_inuse(struct cachefiles_cache *, char *);
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static int cachefiles_daemon_secctx(struct cachefiles_cache *, char *);
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static int cachefiles_daemon_tag(struct cachefiles_cache *, char *);
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static int cachefiles_daemon_bind(struct cachefiles_cache *, char *);
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static void cachefiles_daemon_unbind(struct cachefiles_cache *);
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static unsigned long cachefiles_open;
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const struct file_operations cachefiles_daemon_fops = {
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.owner = THIS_MODULE,
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.open = cachefiles_daemon_open,
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.release = cachefiles_daemon_release,
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.read = cachefiles_daemon_read,
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.write = cachefiles_daemon_write,
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.poll = cachefiles_daemon_poll,
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.llseek = noop_llseek,
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};
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struct cachefiles_daemon_cmd {
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char name[8];
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int (*handler)(struct cachefiles_cache *cache, char *args);
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};
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static const struct cachefiles_daemon_cmd cachefiles_daemon_cmds[] = {
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{ "bind", cachefiles_daemon_bind },
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{ "brun", cachefiles_daemon_brun },
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{ "bcull", cachefiles_daemon_bcull },
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{ "bstop", cachefiles_daemon_bstop },
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{ "cull", cachefiles_daemon_cull },
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{ "debug", cachefiles_daemon_debug },
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{ "dir", cachefiles_daemon_dir },
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{ "frun", cachefiles_daemon_frun },
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{ "fcull", cachefiles_daemon_fcull },
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{ "fstop", cachefiles_daemon_fstop },
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{ "inuse", cachefiles_daemon_inuse },
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{ "secctx", cachefiles_daemon_secctx },
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{ "tag", cachefiles_daemon_tag },
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#ifdef CONFIG_CACHEFILES_ONDEMAND
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{ "copen", cachefiles_ondemand_copen },
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#endif
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{ "", NULL }
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};
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/*
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* Prepare a cache for caching.
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*/
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static int cachefiles_daemon_open(struct inode *inode, struct file *file)
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{
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struct cachefiles_cache *cache;
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_enter("");
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/* only the superuser may do this */
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if (!capable(CAP_SYS_ADMIN))
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return -EPERM;
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/* the cachefiles device may only be open once at a time */
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if (xchg(&cachefiles_open, 1) == 1)
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return -EBUSY;
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/* allocate a cache record */
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cache = kzalloc(sizeof(struct cachefiles_cache), GFP_KERNEL);
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if (!cache) {
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cachefiles_open = 0;
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return -ENOMEM;
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}
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mutex_init(&cache->daemon_mutex);
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init_waitqueue_head(&cache->daemon_pollwq);
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INIT_LIST_HEAD(&cache->volumes);
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INIT_LIST_HEAD(&cache->object_list);
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spin_lock_init(&cache->object_list_lock);
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refcount_set(&cache->unbind_pincount, 1);
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xa_init_flags(&cache->reqs, XA_FLAGS_ALLOC);
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xa_init_flags(&cache->ondemand_ids, XA_FLAGS_ALLOC1);
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/* set default caching limits
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* - limit at 1% free space and/or free files
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* - cull below 5% free space and/or free files
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* - cease culling above 7% free space and/or free files
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*/
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cache->frun_percent = 7;
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cache->fcull_percent = 5;
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cache->fstop_percent = 1;
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cache->brun_percent = 7;
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cache->bcull_percent = 5;
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cache->bstop_percent = 1;
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file->private_data = cache;
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cache->cachefilesd = file;
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return 0;
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}
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static void cachefiles_flush_reqs(struct cachefiles_cache *cache)
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{
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struct xarray *xa = &cache->reqs;
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struct cachefiles_req *req;
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unsigned long index;
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/*
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* Make sure the following two operations won't be reordered.
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* 1) set CACHEFILES_DEAD bit
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* 2) flush requests in the xarray
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* Otherwise the request may be enqueued after xarray has been
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* flushed, leaving the orphan request never being completed.
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*
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* CPU 1 CPU 2
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* ===== =====
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* flush requests in the xarray
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* test CACHEFILES_DEAD bit
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* enqueue the request
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* set CACHEFILES_DEAD bit
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*/
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smp_mb();
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xa_lock(xa);
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xa_for_each(xa, index, req) {
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req->error = -EIO;
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complete(&req->done);
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}
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xa_unlock(xa);
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xa_destroy(&cache->reqs);
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xa_destroy(&cache->ondemand_ids);
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}
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void cachefiles_put_unbind_pincount(struct cachefiles_cache *cache)
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{
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if (refcount_dec_and_test(&cache->unbind_pincount)) {
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cachefiles_daemon_unbind(cache);
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cachefiles_open = 0;
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kfree(cache);
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}
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}
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void cachefiles_get_unbind_pincount(struct cachefiles_cache *cache)
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{
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refcount_inc(&cache->unbind_pincount);
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}
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/*
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* Release a cache.
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*/
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static int cachefiles_daemon_release(struct inode *inode, struct file *file)
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{
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struct cachefiles_cache *cache = file->private_data;
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_enter("");
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ASSERT(cache);
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set_bit(CACHEFILES_DEAD, &cache->flags);
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if (cachefiles_in_ondemand_mode(cache))
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cachefiles_flush_reqs(cache);
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/* clean up the control file interface */
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cache->cachefilesd = NULL;
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file->private_data = NULL;
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cachefiles_put_unbind_pincount(cache);
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_leave("");
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return 0;
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}
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static ssize_t cachefiles_do_daemon_read(struct cachefiles_cache *cache,
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char __user *_buffer, size_t buflen)
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{
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unsigned long long b_released;
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unsigned f_released;
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char buffer[256];
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int n;
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/* check how much space the cache has */
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cachefiles_has_space(cache, 0, 0, cachefiles_has_space_check);
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/* summarise */
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f_released = atomic_xchg(&cache->f_released, 0);
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b_released = atomic_long_xchg(&cache->b_released, 0);
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clear_bit(CACHEFILES_STATE_CHANGED, &cache->flags);
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n = snprintf(buffer, sizeof(buffer),
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"cull=%c"
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" frun=%llx"
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" fcull=%llx"
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" fstop=%llx"
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" brun=%llx"
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" bcull=%llx"
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" bstop=%llx"
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" freleased=%x"
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" breleased=%llx",
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test_bit(CACHEFILES_CULLING, &cache->flags) ? '1' : '0',
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(unsigned long long) cache->frun,
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(unsigned long long) cache->fcull,
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(unsigned long long) cache->fstop,
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(unsigned long long) cache->brun,
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(unsigned long long) cache->bcull,
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(unsigned long long) cache->bstop,
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f_released,
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b_released);
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if (n > buflen)
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return -EMSGSIZE;
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if (copy_to_user(_buffer, buffer, n) != 0)
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return -EFAULT;
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return n;
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}
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/*
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* Read the cache state.
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*/
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static ssize_t cachefiles_daemon_read(struct file *file, char __user *_buffer,
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size_t buflen, loff_t *pos)
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{
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struct cachefiles_cache *cache = file->private_data;
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//_enter(",,%zu,", buflen);
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if (!test_bit(CACHEFILES_READY, &cache->flags))
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return 0;
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if (cachefiles_in_ondemand_mode(cache))
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return cachefiles_ondemand_daemon_read(cache, _buffer, buflen);
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else
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return cachefiles_do_daemon_read(cache, _buffer, buflen);
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}
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/*
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* Take a command from cachefilesd, parse it and act on it.
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*/
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static ssize_t cachefiles_daemon_write(struct file *file,
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const char __user *_data,
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size_t datalen,
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loff_t *pos)
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{
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const struct cachefiles_daemon_cmd *cmd;
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struct cachefiles_cache *cache = file->private_data;
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ssize_t ret;
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char *data, *args, *cp;
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//_enter(",,%zu,", datalen);
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ASSERT(cache);
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if (test_bit(CACHEFILES_DEAD, &cache->flags))
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return -EIO;
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if (datalen > PAGE_SIZE - 1)
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return -EOPNOTSUPP;
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/* drag the command string into the kernel so we can parse it */
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data = memdup_user_nul(_data, datalen);
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if (IS_ERR(data))
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return PTR_ERR(data);
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ret = -EINVAL;
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if (memchr(data, '\0', datalen))
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goto error;
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/* strip any newline */
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cp = memchr(data, '\n', datalen);
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if (cp) {
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if (cp == data)
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goto error;
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*cp = '\0';
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}
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/* parse the command */
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ret = -EOPNOTSUPP;
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for (args = data; *args; args++)
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if (isspace(*args))
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break;
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if (*args) {
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if (args == data)
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goto error;
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*args = '\0';
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args = skip_spaces(++args);
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}
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/* run the appropriate command handler */
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for (cmd = cachefiles_daemon_cmds; cmd->name[0]; cmd++)
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if (strcmp(cmd->name, data) == 0)
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goto found_command;
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error:
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kfree(data);
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//_leave(" = %zd", ret);
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return ret;
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found_command:
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mutex_lock(&cache->daemon_mutex);
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ret = -EIO;
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if (!test_bit(CACHEFILES_DEAD, &cache->flags))
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ret = cmd->handler(cache, args);
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mutex_unlock(&cache->daemon_mutex);
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if (ret == 0)
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ret = datalen;
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goto error;
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}
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/*
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* Poll for culling state
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* - use EPOLLOUT to indicate culling state
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*/
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static __poll_t cachefiles_daemon_poll(struct file *file,
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struct poll_table_struct *poll)
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{
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struct cachefiles_cache *cache = file->private_data;
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__poll_t mask;
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poll_wait(file, &cache->daemon_pollwq, poll);
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mask = 0;
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if (cachefiles_in_ondemand_mode(cache)) {
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if (!xa_empty(&cache->reqs))
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mask |= EPOLLIN;
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} else {
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if (test_bit(CACHEFILES_STATE_CHANGED, &cache->flags))
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mask |= EPOLLIN;
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}
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if (test_bit(CACHEFILES_CULLING, &cache->flags))
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mask |= EPOLLOUT;
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return mask;
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}
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/*
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* Give a range error for cache space constraints
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* - can be tail-called
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*/
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static int cachefiles_daemon_range_error(struct cachefiles_cache *cache,
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char *args)
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{
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pr_err("Free space limits must be in range 0%%<=stop<cull<run<100%%\n");
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return -EINVAL;
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}
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/*
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* Set the percentage of files at which to stop culling
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* - command: "frun <N>%"
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*/
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static int cachefiles_daemon_frun(struct cachefiles_cache *cache, char *args)
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{
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unsigned long frun;
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_enter(",%s", args);
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if (!*args)
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return -EINVAL;
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frun = simple_strtoul(args, &args, 10);
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if (args[0] != '%' || args[1] != '\0')
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return -EINVAL;
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if (frun <= cache->fcull_percent || frun >= 100)
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return cachefiles_daemon_range_error(cache, args);
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cache->frun_percent = frun;
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return 0;
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}
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/*
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* Set the percentage of files at which to start culling
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* - command: "fcull <N>%"
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*/
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static int cachefiles_daemon_fcull(struct cachefiles_cache *cache, char *args)
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{
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unsigned long fcull;
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_enter(",%s", args);
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if (!*args)
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return -EINVAL;
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fcull = simple_strtoul(args, &args, 10);
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if (args[0] != '%' || args[1] != '\0')
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return -EINVAL;
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if (fcull <= cache->fstop_percent || fcull >= cache->frun_percent)
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return cachefiles_daemon_range_error(cache, args);
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cache->fcull_percent = fcull;
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return 0;
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}
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/*
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* Set the percentage of files at which to stop allocating
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* - command: "fstop <N>%"
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*/
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static int cachefiles_daemon_fstop(struct cachefiles_cache *cache, char *args)
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{
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unsigned long fstop;
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_enter(",%s", args);
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if (!*args)
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return -EINVAL;
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fstop = simple_strtoul(args, &args, 10);
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if (args[0] != '%' || args[1] != '\0')
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return -EINVAL;
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if (fstop >= cache->fcull_percent)
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return cachefiles_daemon_range_error(cache, args);
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cache->fstop_percent = fstop;
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return 0;
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}
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/*
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* Set the percentage of blocks at which to stop culling
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* - command: "brun <N>%"
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*/
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static int cachefiles_daemon_brun(struct cachefiles_cache *cache, char *args)
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{
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unsigned long brun;
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_enter(",%s", args);
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if (!*args)
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return -EINVAL;
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brun = simple_strtoul(args, &args, 10);
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if (args[0] != '%' || args[1] != '\0')
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return -EINVAL;
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if (brun <= cache->bcull_percent || brun >= 100)
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return cachefiles_daemon_range_error(cache, args);
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cache->brun_percent = brun;
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return 0;
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}
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/*
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* Set the percentage of blocks at which to start culling
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* - command: "bcull <N>%"
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*/
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static int cachefiles_daemon_bcull(struct cachefiles_cache *cache, char *args)
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{
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unsigned long bcull;
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_enter(",%s", args);
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if (!*args)
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return -EINVAL;
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bcull = simple_strtoul(args, &args, 10);
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if (args[0] != '%' || args[1] != '\0')
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return -EINVAL;
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if (bcull <= cache->bstop_percent || bcull >= cache->brun_percent)
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return cachefiles_daemon_range_error(cache, args);
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cache->bcull_percent = bcull;
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return 0;
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}
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/*
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* Set the percentage of blocks at which to stop allocating
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* - command: "bstop <N>%"
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*/
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static int cachefiles_daemon_bstop(struct cachefiles_cache *cache, char *args)
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{
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unsigned long bstop;
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_enter(",%s", args);
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if (!*args)
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return -EINVAL;
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bstop = simple_strtoul(args, &args, 10);
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if (args[0] != '%' || args[1] != '\0')
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return -EINVAL;
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if (bstop >= cache->bcull_percent)
|
|
return cachefiles_daemon_range_error(cache, args);
|
|
|
|
cache->bstop_percent = bstop;
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Set the cache directory
|
|
* - command: "dir <name>"
|
|
*/
|
|
static int cachefiles_daemon_dir(struct cachefiles_cache *cache, char *args)
|
|
{
|
|
char *dir;
|
|
|
|
_enter(",%s", args);
|
|
|
|
if (!*args) {
|
|
pr_err("Empty directory specified\n");
|
|
return -EINVAL;
|
|
}
|
|
|
|
if (cache->rootdirname) {
|
|
pr_err("Second cache directory specified\n");
|
|
return -EEXIST;
|
|
}
|
|
|
|
dir = kstrdup(args, GFP_KERNEL);
|
|
if (!dir)
|
|
return -ENOMEM;
|
|
|
|
cache->rootdirname = dir;
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Set the cache security context
|
|
* - command: "secctx <ctx>"
|
|
*/
|
|
static int cachefiles_daemon_secctx(struct cachefiles_cache *cache, char *args)
|
|
{
|
|
char *secctx;
|
|
|
|
_enter(",%s", args);
|
|
|
|
if (!*args) {
|
|
pr_err("Empty security context specified\n");
|
|
return -EINVAL;
|
|
}
|
|
|
|
if (cache->secctx) {
|
|
pr_err("Second security context specified\n");
|
|
return -EINVAL;
|
|
}
|
|
|
|
secctx = kstrdup(args, GFP_KERNEL);
|
|
if (!secctx)
|
|
return -ENOMEM;
|
|
|
|
cache->secctx = secctx;
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Set the cache tag
|
|
* - command: "tag <name>"
|
|
*/
|
|
static int cachefiles_daemon_tag(struct cachefiles_cache *cache, char *args)
|
|
{
|
|
char *tag;
|
|
|
|
_enter(",%s", args);
|
|
|
|
if (!*args) {
|
|
pr_err("Empty tag specified\n");
|
|
return -EINVAL;
|
|
}
|
|
|
|
if (cache->tag)
|
|
return -EEXIST;
|
|
|
|
tag = kstrdup(args, GFP_KERNEL);
|
|
if (!tag)
|
|
return -ENOMEM;
|
|
|
|
cache->tag = tag;
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Request a node in the cache be culled from the current working directory
|
|
* - command: "cull <name>"
|
|
*/
|
|
static int cachefiles_daemon_cull(struct cachefiles_cache *cache, char *args)
|
|
{
|
|
struct path path;
|
|
const struct cred *saved_cred;
|
|
int ret;
|
|
|
|
_enter(",%s", args);
|
|
|
|
if (strchr(args, '/'))
|
|
goto inval;
|
|
|
|
if (!test_bit(CACHEFILES_READY, &cache->flags)) {
|
|
pr_err("cull applied to unready cache\n");
|
|
return -EIO;
|
|
}
|
|
|
|
if (test_bit(CACHEFILES_DEAD, &cache->flags)) {
|
|
pr_err("cull applied to dead cache\n");
|
|
return -EIO;
|
|
}
|
|
|
|
get_fs_pwd(current->fs, &path);
|
|
|
|
if (!d_can_lookup(path.dentry))
|
|
goto notdir;
|
|
|
|
cachefiles_begin_secure(cache, &saved_cred);
|
|
ret = cachefiles_cull(cache, path.dentry, args);
|
|
cachefiles_end_secure(cache, saved_cred);
|
|
|
|
path_put(&path);
|
|
_leave(" = %d", ret);
|
|
return ret;
|
|
|
|
notdir:
|
|
path_put(&path);
|
|
pr_err("cull command requires dirfd to be a directory\n");
|
|
return -ENOTDIR;
|
|
|
|
inval:
|
|
pr_err("cull command requires dirfd and filename\n");
|
|
return -EINVAL;
|
|
}
|
|
|
|
/*
|
|
* Set debugging mode
|
|
* - command: "debug <mask>"
|
|
*/
|
|
static int cachefiles_daemon_debug(struct cachefiles_cache *cache, char *args)
|
|
{
|
|
unsigned long mask;
|
|
|
|
_enter(",%s", args);
|
|
|
|
mask = simple_strtoul(args, &args, 0);
|
|
if (args[0] != '\0')
|
|
goto inval;
|
|
|
|
cachefiles_debug = mask;
|
|
_leave(" = 0");
|
|
return 0;
|
|
|
|
inval:
|
|
pr_err("debug command requires mask\n");
|
|
return -EINVAL;
|
|
}
|
|
|
|
/*
|
|
* Find out whether an object in the current working directory is in use or not
|
|
* - command: "inuse <name>"
|
|
*/
|
|
static int cachefiles_daemon_inuse(struct cachefiles_cache *cache, char *args)
|
|
{
|
|
struct path path;
|
|
const struct cred *saved_cred;
|
|
int ret;
|
|
|
|
//_enter(",%s", args);
|
|
|
|
if (strchr(args, '/'))
|
|
goto inval;
|
|
|
|
if (!test_bit(CACHEFILES_READY, &cache->flags)) {
|
|
pr_err("inuse applied to unready cache\n");
|
|
return -EIO;
|
|
}
|
|
|
|
if (test_bit(CACHEFILES_DEAD, &cache->flags)) {
|
|
pr_err("inuse applied to dead cache\n");
|
|
return -EIO;
|
|
}
|
|
|
|
get_fs_pwd(current->fs, &path);
|
|
|
|
if (!d_can_lookup(path.dentry))
|
|
goto notdir;
|
|
|
|
cachefiles_begin_secure(cache, &saved_cred);
|
|
ret = cachefiles_check_in_use(cache, path.dentry, args);
|
|
cachefiles_end_secure(cache, saved_cred);
|
|
|
|
path_put(&path);
|
|
//_leave(" = %d", ret);
|
|
return ret;
|
|
|
|
notdir:
|
|
path_put(&path);
|
|
pr_err("inuse command requires dirfd to be a directory\n");
|
|
return -ENOTDIR;
|
|
|
|
inval:
|
|
pr_err("inuse command requires dirfd and filename\n");
|
|
return -EINVAL;
|
|
}
|
|
|
|
/*
|
|
* Bind a directory as a cache
|
|
*/
|
|
static int cachefiles_daemon_bind(struct cachefiles_cache *cache, char *args)
|
|
{
|
|
_enter("{%u,%u,%u,%u,%u,%u},%s",
|
|
cache->frun_percent,
|
|
cache->fcull_percent,
|
|
cache->fstop_percent,
|
|
cache->brun_percent,
|
|
cache->bcull_percent,
|
|
cache->bstop_percent,
|
|
args);
|
|
|
|
if (cache->fstop_percent >= cache->fcull_percent ||
|
|
cache->fcull_percent >= cache->frun_percent ||
|
|
cache->frun_percent >= 100)
|
|
return -ERANGE;
|
|
|
|
if (cache->bstop_percent >= cache->bcull_percent ||
|
|
cache->bcull_percent >= cache->brun_percent ||
|
|
cache->brun_percent >= 100)
|
|
return -ERANGE;
|
|
|
|
if (!cache->rootdirname) {
|
|
pr_err("No cache directory specified\n");
|
|
return -EINVAL;
|
|
}
|
|
|
|
/* Don't permit already bound caches to be re-bound */
|
|
if (test_bit(CACHEFILES_READY, &cache->flags)) {
|
|
pr_err("Cache already bound\n");
|
|
return -EBUSY;
|
|
}
|
|
|
|
if (IS_ENABLED(CONFIG_CACHEFILES_ONDEMAND)) {
|
|
if (!strcmp(args, "ondemand")) {
|
|
set_bit(CACHEFILES_ONDEMAND_MODE, &cache->flags);
|
|
} else if (*args) {
|
|
pr_err("Invalid argument to the 'bind' command\n");
|
|
return -EINVAL;
|
|
}
|
|
} else if (*args) {
|
|
pr_err("'bind' command doesn't take an argument\n");
|
|
return -EINVAL;
|
|
}
|
|
|
|
/* Make sure we have copies of the tag string */
|
|
if (!cache->tag) {
|
|
/*
|
|
* The tag string is released by the fops->release()
|
|
* function, so we don't release it on error here
|
|
*/
|
|
cache->tag = kstrdup("CacheFiles", GFP_KERNEL);
|
|
if (!cache->tag)
|
|
return -ENOMEM;
|
|
}
|
|
|
|
return cachefiles_add_cache(cache);
|
|
}
|
|
|
|
/*
|
|
* Unbind a cache.
|
|
*/
|
|
static void cachefiles_daemon_unbind(struct cachefiles_cache *cache)
|
|
{
|
|
_enter("");
|
|
|
|
if (test_bit(CACHEFILES_READY, &cache->flags))
|
|
cachefiles_withdraw_cache(cache);
|
|
|
|
cachefiles_put_directory(cache->graveyard);
|
|
cachefiles_put_directory(cache->store);
|
|
mntput(cache->mnt);
|
|
|
|
kfree(cache->rootdirname);
|
|
kfree(cache->secctx);
|
|
kfree(cache->tag);
|
|
|
|
_leave("");
|
|
}
|