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80f94f29f6
Provide a function to check how much space there is. This also flips the state on the cache and will signal the daemon to inform it of the change and to ask it to do some culling if necessary. We will also need to subtract the amount of data currently being written to the cache (cache->b_writing) from the amount of available space to avoid hitting ENOSPC accidentally. Signed-off-by: David Howells <dhowells@redhat.com> Reviewed-by: Jeff Layton <jlayton@kernel.org> cc: linux-cachefs@redhat.com Link: https://lore.kernel.org/r/163819629322.215744.13457425294680841213.stgit@warthog.procyon.org.uk/ # v1 Link: https://lore.kernel.org/r/163906930100.143852.1681026700865762069.stgit@warthog.procyon.org.uk/ # v2 Link: https://lore.kernel.org/r/163967140058.1823006.7781243664702837128.stgit@warthog.procyon.org.uk/ # v3 Link: https://lore.kernel.org/r/164021539957.640689.12477177372616805706.stgit@warthog.procyon.org.uk/ # v4
725 lines
16 KiB
C
725 lines
16 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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{ "", 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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/* 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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/*
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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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cachefiles_daemon_unbind(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_open = 0;
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kfree(cache);
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_leave("");
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return 0;
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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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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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//_enter(",,%zu,", buflen);
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if (!test_bit(CACHEFILES_READY, &cache->flags))
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return 0;
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/* check how much space the cache has */
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cachefiles_has_space(cache, 0, 0);
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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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* 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 (test_bit(CACHEFILES_STATE_CHANGED, &cache->flags))
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mask |= EPOLLIN;
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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)
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return cachefiles_daemon_range_error(cache, args);
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cache->bstop_percent = bstop;
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return 0;
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}
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/*
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* Set the cache directory
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* - command: "dir <name>"
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*/
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static int cachefiles_daemon_dir(struct cachefiles_cache *cache, char *args)
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{
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char *dir;
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_enter(",%s", args);
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if (!*args) {
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pr_err("Empty directory specified\n");
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return -EINVAL;
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}
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if (cache->rootdirname) {
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pr_err("Second cache directory specified\n");
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return -EEXIST;
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}
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dir = kstrdup(args, GFP_KERNEL);
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if (!dir)
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return -ENOMEM;
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cache->rootdirname = dir;
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return 0;
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}
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/*
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* Set the cache security context
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* - command: "secctx <ctx>"
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*/
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static int cachefiles_daemon_secctx(struct cachefiles_cache *cache, char *args)
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{
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char *secctx;
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_enter(",%s", args);
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if (!*args) {
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pr_err("Empty security context specified\n");
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return -EINVAL;
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}
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if (cache->secctx) {
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pr_err("Second security context specified\n");
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return -EINVAL;
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}
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secctx = kstrdup(args, GFP_KERNEL);
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if (!secctx)
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return -ENOMEM;
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cache->secctx = secctx;
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return 0;
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}
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/*
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* Set the cache tag
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* - command: "tag <name>"
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*/
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static int cachefiles_daemon_tag(struct cachefiles_cache *cache, char *args)
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{
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char *tag;
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_enter(",%s", args);
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if (!*args) {
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pr_err("Empty tag specified\n");
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return -EINVAL;
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}
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if (cache->tag)
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return -EEXIST;
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|
|
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 = -ENOANO; // PLACEHOLDER: Do culling
|
|
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 = -ENOANO; // PLACEHOLDER: Check if in use
|
|
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 (*args) {
|
|
pr_err("'bind' command doesn't take an argument\n");
|
|
return -EINVAL;
|
|
}
|
|
|
|
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;
|
|
}
|
|
|
|
pr_warn("Cache is disabled for development\n");
|
|
return -ENOANO; // Don't allow the cache to operate yet
|
|
}
|
|
|
|
/*
|
|
* Unbind a cache.
|
|
*/
|
|
static void cachefiles_daemon_unbind(struct cachefiles_cache *cache)
|
|
{
|
|
_enter("");
|
|
|
|
if (test_bit(CACHEFILES_READY, &cache->flags)) {
|
|
// PLACEHOLDER: Withdraw cache
|
|
}
|
|
|
|
mntput(cache->mnt);
|
|
|
|
kfree(cache->rootdirname);
|
|
kfree(cache->secctx);
|
|
kfree(cache->tag);
|
|
|
|
_leave("");
|
|
}
|