[mirror_ubuntu-bionic-kernel.git] / fs / cachefiles / daemon.c

/* Daemon interface
 *
 * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
 * Written by David Howells (dhowells@redhat.com)
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public Licence
 * as published by the Free Software Foundation; either version
 * 2 of the Licence, or (at your option) any later version.
 */

#include <linux/module.h>
#include <linux/init.h>
#include <linux/sched.h>
#include <linux/completion.h>
#include <linux/slab.h>
#include <linux/fs.h>
#include <linux/file.h>
#include <linux/namei.h>
#include <linux/poll.h>
#include <linux/mount.h>
#include <linux/statfs.h>
#include <linux/ctype.h>
#include <linux/string.h>
#include <linux/fs_struct.h>
#include "internal.h"

static int cachefiles_daemon_open(struct inode *, struct file *);
static int cachefiles_daemon_release(struct inode *, struct file *);
static ssize_t cachefiles_daemon_read(struct file *, char __user *, size_t,
				      loff_t *);
static ssize_t cachefiles_daemon_write(struct file *, const char __user *,
				       size_t, loff_t *);
static unsigned int cachefiles_daemon_poll(struct file *,
					   struct poll_table_struct *);
static int cachefiles_daemon_frun(struct cachefiles_cache *, char *);
static int cachefiles_daemon_fcull(struct cachefiles_cache *, char *);
static int cachefiles_daemon_fstop(struct cachefiles_cache *, char *);
static int cachefiles_daemon_brun(struct cachefiles_cache *, char *);
static int cachefiles_daemon_bcull(struct cachefiles_cache *, char *);
static int cachefiles_daemon_bstop(struct cachefiles_cache *, char *);
static int cachefiles_daemon_cull(struct cachefiles_cache *, char *);
static int cachefiles_daemon_debug(struct cachefiles_cache *, char *);
static int cachefiles_daemon_dir(struct cachefiles_cache *, char *);
static int cachefiles_daemon_inuse(struct cachefiles_cache *, char *);
static int cachefiles_daemon_secctx(struct cachefiles_cache *, char *);
static int cachefiles_daemon_tag(struct cachefiles_cache *, char *);

static unsigned long cachefiles_open;

const struct file_operations cachefiles_daemon_fops = {
	.owner		= THIS_MODULE,
	.open		= cachefiles_daemon_open,
	.release	= cachefiles_daemon_release,
	.read		= cachefiles_daemon_read,
	.write		= cachefiles_daemon_write,
	.poll		= cachefiles_daemon_poll,
	.llseek		= noop_llseek,
};

struct cachefiles_daemon_cmd {
	char name[8];
	int (*handler)(struct cachefiles_cache *cache, char *args);
};

static const struct cachefiles_daemon_cmd cachefiles_daemon_cmds[] = {
	{ "bind",	cachefiles_daemon_bind		},
	{ "brun",	cachefiles_daemon_brun		},
	{ "bcull",	cachefiles_daemon_bcull		},
	{ "bstop",	cachefiles_daemon_bstop		},
	{ "cull",	cachefiles_daemon_cull		},
	{ "debug",	cachefiles_daemon_debug		},
	{ "dir",	cachefiles_daemon_dir		},
	{ "frun",	cachefiles_daemon_frun		},
	{ "fcull",	cachefiles_daemon_fcull		},
	{ "fstop",	cachefiles_daemon_fstop		},
	{ "inuse",	cachefiles_daemon_inuse		},
	{ "secctx",	cachefiles_daemon_secctx	},
	{ "tag",	cachefiles_daemon_tag		},
	{ "",		NULL				}
};


/*
 * do various checks
 */
static int cachefiles_daemon_open(struct inode *inode, struct file *file)
{
	struct cachefiles_cache *cache;

	_enter("");

	/* only the superuser may do this */
	if (!capable(CAP_SYS_ADMIN))
		return -EPERM;

	/* the cachefiles device may only be open once at a time */
	if (xchg(&cachefiles_open, 1) == 1)
		return -EBUSY;

	/* allocate a cache record */
	cache = kzalloc(sizeof(struct cachefiles_cache), GFP_KERNEL);
	if (!cache) {
		cachefiles_open = 0;
		return -ENOMEM;
	}

	mutex_init(&cache->daemon_mutex);
	cache->active_nodes = RB_ROOT;
	rwlock_init(&cache->active_lock);
	init_waitqueue_head(&cache->daemon_pollwq);

	/* set default caching limits
	 * - limit at 1% free space and/or free files
	 * - cull below 5% free space and/or free files
	 * - cease culling above 7% free space and/or free files
	 */
	cache->frun_percent = 7;
	cache->fcull_percent = 5;
	cache->fstop_percent = 1;
	cache->brun_percent = 7;
	cache->bcull_percent = 5;
	cache->bstop_percent = 1;

	file->private_data = cache;
	cache->cachefilesd = file;
	return 0;
}

/*
 * release a cache
 */
static int cachefiles_daemon_release(struct inode *inode, struct file *file)
{
	struct cachefiles_cache *cache = file->private_data;

	_enter("");

	ASSERT(cache);

	set_bit(CACHEFILES_DEAD, &cache->flags);

	cachefiles_daemon_unbind(cache);

	ASSERT(!cache->active_nodes.rb_node);

	/* clean up the control file interface */
	cache->cachefilesd = NULL;
	file->private_data = NULL;
	cachefiles_open = 0;

	kfree(cache);

	_leave("");
	return 0;
}

/*
 * read the cache state
 */
static ssize_t cachefiles_daemon_read(struct file *file, char __user *_buffer,
				      size_t buflen, loff_t *pos)
{
	struct cachefiles_cache *cache = file->private_data;
	char buffer[256];
	int n;

	//_enter(",,%zu,", buflen);

	if (!test_bit(CACHEFILES_READY, &cache->flags))
		return 0;

	/* check how much space the cache has */
	cachefiles_has_space(cache, 0, 0);

	/* summarise */
	clear_bit(CACHEFILES_STATE_CHANGED, &cache->flags);

	n = snprintf(buffer, sizeof(buffer),
		     "cull=%c"
		     " frun=%llx"
		     " fcull=%llx"
		     " fstop=%llx"
		     " brun=%llx"
		     " bcull=%llx"
		     " bstop=%llx",
		     test_bit(CACHEFILES_CULLING, &cache->flags) ? '1' : '0',
		     (unsigned long long) cache->frun,
		     (unsigned long long) cache->fcull,
		     (unsigned long long) cache->fstop,
		     (unsigned long long) cache->brun,
		     (unsigned long long) cache->bcull,
		     (unsigned long long) cache->bstop
		     );

	if (n > buflen)
		return -EMSGSIZE;

	if (copy_to_user(_buffer, buffer, n) != 0)
		return -EFAULT;

	return n;
}

/*
 * command the cache
 */
static ssize_t cachefiles_daemon_write(struct file *file,
				       const char __user *_data,
				       size_t datalen,
				       loff_t *pos)
{
	const struct cachefiles_daemon_cmd *cmd;
	struct cachefiles_cache *cache = file->private_data;
	ssize_t ret;
	char *data, *args, *cp;

	//_enter(",,%zu,", datalen);

	ASSERT(cache);

	if (test_bit(CACHEFILES_DEAD, &cache->flags))
		return -EIO;

	if (datalen < 0 || datalen > PAGE_SIZE - 1)
		return -EOPNOTSUPP;

	/* drag the command string into the kernel so we can parse it */
	data = kmalloc(datalen + 1, GFP_KERNEL);
	if (!data)
		return -ENOMEM;

	ret = -EFAULT;
	if (copy_from_user(data, _data, datalen) != 0)
		goto error;

	data[datalen] = '\0';

	ret = -EINVAL;
	if (memchr(data, '\0', datalen))
		goto error;

	/* strip any newline */
	cp = memchr(data, '\n', datalen);
	if (cp) {
		if (cp == data)
			goto error;

		*cp = '\0';
	}

	/* parse the command */
	ret = -EOPNOTSUPP;

	for (args = data; *args; args++)
		if (isspace(*args))
			break;
	if (*args) {
		if (args == data)
			goto error;
		*args = '\0';
		args = skip_spaces(++args);
	}

	/* run the appropriate command handler */
	for (cmd = cachefiles_daemon_cmds; cmd->name[0]; cmd++)
		if (strcmp(cmd->name, data) == 0)
			goto found_command;

error:
	kfree(data);
	//_leave(" = %zd", ret);
	return ret;

found_command:
	mutex_lock(&cache->daemon_mutex);

	ret = -EIO;
	if (!test_bit(CACHEFILES_DEAD, &cache->flags))
		ret = cmd->handler(cache, args);

	mutex_unlock(&cache->daemon_mutex);

	if (ret == 0)
		ret = datalen;
	goto error;
}

/*
 * poll for culling state
 * - use POLLOUT to indicate culling state
 */
static unsigned int cachefiles_daemon_poll(struct file *file,
					   struct poll_table_struct *poll)
{
	struct cachefiles_cache *cache = file->private_data;
	unsigned int mask;

	poll_wait(file, &cache->daemon_pollwq, poll);
	mask = 0;

	if (test_bit(CACHEFILES_STATE_CHANGED, &cache->flags))
		mask |= POLLIN;

	if (test_bit(CACHEFILES_CULLING, &cache->flags))
		mask |= POLLOUT;

	return mask;
}

/*
 * give a range error for cache space constraints
 * - can be tail-called
 */
static int cachefiles_daemon_range_error(struct cachefiles_cache *cache,
					 char *args)
{
	pr_err("Free space limits must be in range 0%%<=stop<cull<run<100%%\n");

	return -EINVAL;
}

/*
 * set the percentage of files at which to stop culling
 * - command: "frun <N>%"
 */
static int cachefiles_daemon_frun(struct cachefiles_cache *cache, char *args)
{
	unsigned long frun;

	_enter(",%s", args);

	if (!*args)
		return -EINVAL;

	frun = simple_strtoul(args, &args, 10);
	if (args[0] != '%' || args[1] != '\0')
		return -EINVAL;

	if (frun <= cache->fcull_percent || frun >= 100)
		return cachefiles_daemon_range_error(cache, args);

	cache->frun_percent = frun;
	return 0;
}

/*
 * set the percentage of files at which to start culling
 * - command: "fcull <N>%"
 */
static int cachefiles_daemon_fcull(struct cachefiles_cache *cache, char *args)
{
	unsigned long fcull;

	_enter(",%s", args);

	if (!*args)
		return -EINVAL;

	fcull = simple_strtoul(args, &args, 10);
	if (args[0] != '%' || args[1] != '\0')
		return -EINVAL;

	if (fcull <= cache->fstop_percent || fcull >= cache->frun_percent)
		return cachefiles_daemon_range_error(cache, args);

	cache->fcull_percent = fcull;
	return 0;
}

/*
 * set the percentage of files at which to stop allocating
 * - command: "fstop <N>%"
 */
static int cachefiles_daemon_fstop(struct cachefiles_cache *cache, char *args)
{
	unsigned long fstop;

	_enter(",%s", args);

	if (!*args)
		return -EINVAL;

	fstop = simple_strtoul(args, &args, 10);
	if (args[0] != '%' || args[1] != '\0')
		return -EINVAL;

	if (fstop < 0 || fstop >= cache->fcull_percent)
		return cachefiles_daemon_range_error(cache, args);

	cache->fstop_percent = fstop;
	return 0;
}

/*
 * set the percentage of blocks at which to stop culling
 * - command: "brun <N>%"
 */
static int cachefiles_daemon_brun(struct cachefiles_cache *cache, char *args)
{
	unsigned long brun;

	_enter(",%s", args);

	if (!*args)
		return -EINVAL;

	brun = simple_strtoul(args, &args, 10);
	if (args[0] != '%' || args[1] != '\0')
		return -EINVAL;

	if (brun <= cache->bcull_percent || brun >= 100)
		return cachefiles_daemon_range_error(cache, args);

	cache->brun_percent = brun;
	return 0;
}

/*
 * set the percentage of blocks at which to start culling
 * - command: "bcull <N>%"
 */
static int cachefiles_daemon_bcull(struct cachefiles_cache *cache, char *args)
{
	unsigned long bcull;

	_enter(",%s", args);

	if (!*args)
		return -EINVAL;

	bcull = simple_strtoul(args, &args, 10);
	if (args[0] != '%' || args[1] != '\0')
		return -EINVAL;

	if (bcull <= cache->bstop_percent || bcull >= cache->brun_percent)
		return cachefiles_daemon_range_error(cache, args);

	cache->bcull_percent = bcull;
	return 0;
}

/*
 * set the percentage of blocks at which to stop allocating
 * - command: "bstop <N>%"
 */
static int cachefiles_daemon_bstop(struct cachefiles_cache *cache, char *args)
{
	unsigned long bstop;

	_enter(",%s", args);

	if (!*args)
		return -EINVAL;

	bstop = simple_strtoul(args, &args, 10);
	if (args[0] != '%' || args[1] != '\0')
		return -EINVAL;

	if (bstop < 0 || 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;
	}

	/* extract the directory dentry from the cwd */
	get_fs_pwd(current->fs, &path);

	if (!S_ISDIR(path.dentry->d_inode->i_mode))
		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;
	}

	/* extract the directory dentry from the cwd */
	get_fs_pwd(current->fs, &path);

	if (!S_ISDIR(path.dentry->d_inode->i_mode))
		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;
}

/*
 * see if we have space for a number of pages and/or a number of files in the
 * cache
 */
int cachefiles_has_space(struct cachefiles_cache *cache,
			 unsigned fnr, unsigned bnr)
{
	struct kstatfs stats;
	struct path path = {
		.mnt	= cache->mnt,
		.dentry	= cache->mnt->mnt_root,
	};
	int ret;

	//_enter("{%llu,%llu,%llu,%llu,%llu,%llu},%u,%u",
	//       (unsigned long long) cache->frun,
	//       (unsigned long long) cache->fcull,
	//       (unsigned long long) cache->fstop,
	//       (unsigned long long) cache->brun,
	//       (unsigned long long) cache->bcull,
	//       (unsigned long long) cache->bstop,
	//       fnr, bnr);

	/* find out how many pages of blockdev are available */
	memset(&stats, 0, sizeof(stats));

	ret = vfs_statfs(&path, &stats);
	if (ret < 0) {
		if (ret == -EIO)
			cachefiles_io_error(cache, "statfs failed");
		_leave(" = %d", ret);
		return ret;
	}

	stats.f_bavail >>= cache->bshift;

	//_debug("avail %llu,%llu",
	//       (unsigned long long) stats.f_ffree,
	//       (unsigned long long) stats.f_bavail);

	/* see if there is sufficient space */
	if (stats.f_ffree > fnr)
		stats.f_ffree -= fnr;
	else
		stats.f_ffree = 0;

	if (stats.f_bavail > bnr)
		stats.f_bavail -= bnr;
	else
		stats.f_bavail = 0;

	ret = -ENOBUFS;
	if (stats.f_ffree < cache->fstop ||
	    stats.f_bavail < cache->bstop)
		goto begin_cull;

	ret = 0;
	if (stats.f_ffree < cache->fcull ||
	    stats.f_bavail < cache->bcull)
		goto begin_cull;

	if (test_bit(CACHEFILES_CULLING, &cache->flags) &&
	    stats.f_ffree >= cache->frun &&
	    stats.f_bavail >= cache->brun &&
	    test_and_clear_bit(CACHEFILES_CULLING, &cache->flags)
	    ) {
		_debug("cease culling");
		cachefiles_state_changed(cache);
	}

	//_leave(" = 0");
	return 0;

begin_cull:
	if (!test_and_set_bit(CACHEFILES_CULLING, &cache->flags)) {
		_debug("### CULL CACHE ###");
		cachefiles_state_changed(cache);
	}

	_leave(" = %d", ret);
	return ret;
}
Commit	Line	Data
9ae326a6 DH	1	/* Daemon interface
	2	*
	3	* Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
	4	* Written by David Howells (dhowells@redhat.com)
	5	*
	6	* This program is free software; you can redistribute it and/or
	7	* modify it under the terms of the GNU General Public Licence
	8	* as published by the Free Software Foundation; either version
	9	* 2 of the Licence, or (at your option) any later version.
	10	*/
	11
	12	#include <linux/module.h>
	13	#include <linux/init.h>
	14	#include <linux/sched.h>
	15	#include <linux/completion.h>
	16	#include <linux/slab.h>
	17	#include <linux/fs.h>
	18	#include <linux/file.h>
	19	#include <linux/namei.h>
	20	#include <linux/poll.h>
	21	#include <linux/mount.h>
	22	#include <linux/statfs.h>
	23	#include <linux/ctype.h>
e7d2860b	24	#include <linux/string.h>
9ae326a6 DH	25	#include <linux/fs_struct.h>
	26	#include "internal.h"
	27
	28	static int cachefiles_daemon_open(struct inode , struct file );
	29	static int cachefiles_daemon_release(struct inode , struct file );
	30	static ssize_t cachefiles_daemon_read(struct file , char __user , size_t,
	31	loff_t *);
	32	static ssize_t cachefiles_daemon_write(struct file , const char __user ,
	33	size_t, loff_t *);
	34	static unsigned int cachefiles_daemon_poll(struct file *,
	35	struct poll_table_struct *);
	36	static int cachefiles_daemon_frun(struct cachefiles_cache , char );
	37	static int cachefiles_daemon_fcull(struct cachefiles_cache , char );
	38	static int cachefiles_daemon_fstop(struct cachefiles_cache , char );
	39	static int cachefiles_daemon_brun(struct cachefiles_cache , char );
	40	static int cachefiles_daemon_bcull(struct cachefiles_cache , char );
	41	static int cachefiles_daemon_bstop(struct cachefiles_cache , char );
	42	static int cachefiles_daemon_cull(struct cachefiles_cache , char );
	43	static int cachefiles_daemon_debug(struct cachefiles_cache , char );
	44	static int cachefiles_daemon_dir(struct cachefiles_cache , char );
	45	static int cachefiles_daemon_inuse(struct cachefiles_cache , char );
	46	static int cachefiles_daemon_secctx(struct cachefiles_cache , char );
	47	static int cachefiles_daemon_tag(struct cachefiles_cache , char );
	48
	49	static unsigned long cachefiles_open;
	50
	51	const struct file_operations cachefiles_daemon_fops = {
	52	.owner = THIS_MODULE,
	53	.open = cachefiles_daemon_open,
	54	.release = cachefiles_daemon_release,
	55	.read = cachefiles_daemon_read,
	56	.write = cachefiles_daemon_write,
	57	.poll = cachefiles_daemon_poll,
6038f373	58	.llseek = noop_llseek,
9ae326a6 DH	59	};
	60
	61	struct cachefiles_daemon_cmd {
	62	char name[8];
	63	int (handler)(struct cachefiles_cache cache, char *args);
	64	};
	65
	66	static const struct cachefiles_daemon_cmd cachefiles_daemon_cmds[] = {
	67	{ "bind", cachefiles_daemon_bind },
	68	{ "brun", cachefiles_daemon_brun },
	69	{ "bcull", cachefiles_daemon_bcull },
	70	{ "bstop", cachefiles_daemon_bstop },
	71	{ "cull", cachefiles_daemon_cull },
	72	{ "debug", cachefiles_daemon_debug },
	73	{ "dir", cachefiles_daemon_dir },
	74	{ "frun", cachefiles_daemon_frun },
	75	{ "fcull", cachefiles_daemon_fcull },
	76	{ "fstop", cachefiles_daemon_fstop },
	77	{ "inuse", cachefiles_daemon_inuse },
	78	{ "secctx", cachefiles_daemon_secctx },
	79	{ "tag", cachefiles_daemon_tag },
	80	{ "", NULL }
	81	};
	82
	83
	84	/*
	85	* do various checks
	86	*/
	87	static int cachefiles_daemon_open(struct inode inode, struct file file)
	88	{
	89	struct cachefiles_cache *cache;
	90
	91	_enter("");
	92
	93	/* only the superuser may do this */
	94	if (!capable(CAP_SYS_ADMIN))
	95	return -EPERM;
	96
	97	/* the cachefiles device may only be open once at a time */
	98	if (xchg(&cachefiles_open, 1) == 1)
	99	return -EBUSY;
	100
	101	/* allocate a cache record */
	102	cache = kzalloc(sizeof(struct cachefiles_cache), GFP_KERNEL);
	103	if (!cache) {
	104	cachefiles_open = 0;
	105	return -ENOMEM;
	106	}
	107
	108	mutex_init(&cache->daemon_mutex);
	109	cache->active_nodes = RB_ROOT;
	110	rwlock_init(&cache->active_lock);
	111	init_waitqueue_head(&cache->daemon_pollwq);
	112
	113	/* set default caching limits
	114	* - limit at 1% free space and/or free files
	115	* - cull below 5% free space and/or free files
	116	* - cease culling above 7% free space and/or free files
	117	*/
	118	cache->frun_percent = 7;
	119	cache->fcull_percent = 5;
	120	cache->fstop_percent = 1;
	121	cache->brun_percent = 7;
	122	cache->bcull_percent = 5;
123	cache->bstop_percent = 1;
124
125	file->private_data = cache;
126	cache->cachefilesd = file;
127	return 0;
128	}
129
130	/*
131	* release a cache
132	*/
133	static int cachefiles_daemon_release(struct inode inode, struct file file)
134	{
135	struct cachefiles_cache *cache = file->private_data;
136
137	_enter("");
138
139	ASSERT(cache);
140
141	set_bit(CACHEFILES_DEAD, &cache->flags);
142
143	cachefiles_daemon_unbind(cache);
144
145	ASSERT(!cache->active_nodes.rb_node);
146
147	/* clean up the control file interface */
148	cache->cachefilesd = NULL;
149	file->private_data = NULL;
150	cachefiles_open = 0;
151
152	kfree(cache);
153
154	_leave("");
155	return 0;
156	}
157
158	/*
159	* read the cache state
160	*/
161	static ssize_t cachefiles_daemon_read(struct file file, char __user _buffer,
162	size_t buflen, loff_t *pos)
163	{
164	struct cachefiles_cache *cache = file->private_data;
165	char buffer[256];
166	int n;
167
168	//_enter(",,%zu,", buflen);
169
170	if (!test_bit(CACHEFILES_READY, &cache->flags))
171	return 0;
172
173	/* check how much space the cache has */
174	cachefiles_has_space(cache, 0, 0);
175
176	/* summarise */
177	clear_bit(CACHEFILES_STATE_CHANGED, &cache->flags);
178
179	n = snprintf(buffer, sizeof(buffer),
180	"cull=%c"
181	" frun=%llx"
182	" fcull=%llx"
183	" fstop=%llx"
184	" brun=%llx"
185	" bcull=%llx"
186	" bstop=%llx",
187	test_bit(CACHEFILES_CULLING, &cache->flags) ? '1' : '0',
188	(unsigned long long) cache->frun,
189	(unsigned long long) cache->fcull,
190	(unsigned long long) cache->fstop,
191	(unsigned long long) cache->brun,
192	(unsigned long long) cache->bcull,
193	(unsigned long long) cache->bstop
194	);
195
196	if (n > buflen)
197	return -EMSGSIZE;
198
199	if (copy_to_user(_buffer, buffer, n) != 0)
200	return -EFAULT;
201
202	return n;
203	}
204
205	/*
206	* command the cache
207	*/
208	static ssize_t cachefiles_daemon_write(struct file *file,
209	const char __user *_data,
210	size_t datalen,
211	loff_t *pos)
212	{
213	const struct cachefiles_daemon_cmd *cmd;
214	struct cachefiles_cache *cache = file->private_data;
215	ssize_t ret;
216	char data, args, *cp;
217
218	//_enter(",,%zu,", datalen);
219
220	ASSERT(cache);
221
222	if (test_bit(CACHEFILES_DEAD, &cache->flags))
223	return -EIO;
224
225	if (datalen < 0 \|\| datalen > PAGE_SIZE - 1)
226	return -EOPNOTSUPP;
227
228	/* drag the command string into the kernel so we can parse it */
229	data = kmalloc(datalen + 1, GFP_KERNEL);
230	if (!data)
231	return -ENOMEM;
232
233	ret = -EFAULT;
234	if (copy_from_user(data, _data, datalen) != 0)
235	goto error;
236
237	data[datalen] = '\0';
238
239	ret = -EINVAL;
240	if (memchr(data, '\0', datalen))
241	goto error;
242
243	/* strip any newline */
244	cp = memchr(data, '\n', datalen);
245	if (cp) {
246	if (cp == data)
247	goto error;
248
249	*cp = '\0';
250	}
251
252	/* parse the command */
253	ret = -EOPNOTSUPP;
254
255	for (args = data; *args; args++)
256	if (isspace(*args))
257	break;
258	if (*args) {
259	if (args == data)
260	goto error;
261	*args = '\0';
e7d2860b	262	args = skip_spaces(++args);
9ae326a6 DH	263	}
	264
	265	/* run the appropriate command handler */
	266	for (cmd = cachefiles_daemon_cmds; cmd->name[0]; cmd++)
	267	if (strcmp(cmd->name, data) == 0)
	268	goto found_command;
	269
	270	error:
	271	kfree(data);
	272	//_leave(" = %zd", ret);
	273	return ret;
	274
	275	found_command:
	276	mutex_lock(&cache->daemon_mutex);
	277
	278	ret = -EIO;
	279	if (!test_bit(CACHEFILES_DEAD, &cache->flags))
	280	ret = cmd->handler(cache, args);
	281
	282	mutex_unlock(&cache->daemon_mutex);
	283
	284	if (ret == 0)
	285	ret = datalen;
	286	goto error;
	287	}
	288
	289	/*
	290	* poll for culling state
	291	* - use POLLOUT to indicate culling state
	292	*/
	293	static unsigned int cachefiles_daemon_poll(struct file *file,
	294	struct poll_table_struct *poll)
	295	{
	296	struct cachefiles_cache *cache = file->private_data;
	297	unsigned int mask;
	298
	299	poll_wait(file, &cache->daemon_pollwq, poll);
	300	mask = 0;
	301
	302	if (test_bit(CACHEFILES_STATE_CHANGED, &cache->flags))
	303	mask \|= POLLIN;
	304
	305	if (test_bit(CACHEFILES_CULLING, &cache->flags))
	306	mask \|= POLLOUT;
	307
	308	return mask;
	309	}
	310
	311	/*
	312	* give a range error for cache space constraints
	313	* - can be tail-called
	314	*/
	315	static int cachefiles_daemon_range_error(struct cachefiles_cache *cache,
	316	char *args)
	317	{
6ff66ac7	318	pr_err("Free space limits must be in range 0%%<=stop<cull<run<100%%\n");
9ae326a6 DH	319
	320	return -EINVAL;
	321	}
	322
	323	/*
	324	* set the percentage of files at which to stop culling
	325	* - command: "frun <N>%"
	326	*/
	327	static int cachefiles_daemon_frun(struct cachefiles_cache cache, char args)
	328	{
	329	unsigned long frun;
	330
	331	_enter(",%s", args);
	332
	333	if (!*args)
	334	return -EINVAL;
	335
	336	frun = simple_strtoul(args, &args, 10);
	337	if (args[0] != '%' \|\| args[1] != '\0')
	338	return -EINVAL;
	339
	340	if (frun <= cache->fcull_percent \|\| frun >= 100)
	341	return cachefiles_daemon_range_error(cache, args);
	342
	343	cache->frun_percent = frun;
	344	return 0;
	345	}
	346
	347	/*
	348	* set the percentage of files at which to start culling
	349	* - command: "fcull <N>%"
	350	*/
	351	static int cachefiles_daemon_fcull(struct cachefiles_cache cache, char args)
	352	{
	353	unsigned long fcull;
	354
	355	_enter(",%s", args);
	356
	357	if (!*args)
	358	return -EINVAL;
	359
	360	fcull = simple_strtoul(args, &args, 10);
	361	if (args[0] != '%' \|\| args[1] != '\0')
	362	return -EINVAL;
	363
	364	if (fcull <= cache->fstop_percent \|\| fcull >= cache->frun_percent)
	365	return cachefiles_daemon_range_error(cache, args);
	366
	367	cache->fcull_percent = fcull;
	368	return 0;
	369	}
	370
	371	/*
	372	* set the percentage of files at which to stop allocating
	373	* - command: "fstop <N>%"
	374	*/
	375	static int cachefiles_daemon_fstop(struct cachefiles_cache cache, char args)
	376	{
	377	unsigned long fstop;
	378
	379	_enter(",%s", args);
	380
	381	if (!*args)
	382	return -EINVAL;
383
384	fstop = simple_strtoul(args, &args, 10);
385	if (args[0] != '%' \|\| args[1] != '\0')
386	return -EINVAL;
387
388	if (fstop < 0 \|\| fstop >= cache->fcull_percent)
389	return cachefiles_daemon_range_error(cache, args);
390
391	cache->fstop_percent = fstop;
392	return 0;
393	}
394
395	/*
396	* set the percentage of blocks at which to stop culling
397	* - command: "brun <N>%"
398	*/
399	static int cachefiles_daemon_brun(struct cachefiles_cache cache, char args)
400	{
401	unsigned long brun;
402
403	_enter(",%s", args);
404
405	if (!*args)
406	return -EINVAL;
407
408	brun = simple_strtoul(args, &args, 10);
409	if (args[0] != '%' \|\| args[1] != '\0')
410	return -EINVAL;
411
412	if (brun <= cache->bcull_percent \|\| brun >= 100)
413	return cachefiles_daemon_range_error(cache, args);
414
415	cache->brun_percent = brun;
416	return 0;
417	}
418
419	/*
420	* set the percentage of blocks at which to start culling
421	* - command: "bcull <N>%"
422	*/
423	static int cachefiles_daemon_bcull(struct cachefiles_cache cache, char args)
424	{
425	unsigned long bcull;
426
427	_enter(",%s", args);
428
429	if (!*args)
430	return -EINVAL;
431
432	bcull = simple_strtoul(args, &args, 10);
433	if (args[0] != '%' \|\| args[1] != '\0')
434	return -EINVAL;
435
436	if (bcull <= cache->bstop_percent \|\| bcull >= cache->brun_percent)
437	return cachefiles_daemon_range_error(cache, args);
438
439	cache->bcull_percent = bcull;
440	return 0;
441	}
442
443	/*
444	* set the percentage of blocks at which to stop allocating
445	* - command: "bstop <N>%"
446	*/
447	static int cachefiles_daemon_bstop(struct cachefiles_cache cache, char args)
448	{
449	unsigned long bstop;
450
451	_enter(",%s", args);
452
453	if (!*args)
454	return -EINVAL;
455
456	bstop = simple_strtoul(args, &args, 10);
457	if (args[0] != '%' \|\| args[1] != '\0')
458	return -EINVAL;
459
460	if (bstop < 0 \|\| bstop >= cache->bcull_percent)
461	return cachefiles_daemon_range_error(cache, args);
462
463	cache->bstop_percent = bstop;
464	return 0;
465	}
466
467	/*
468	* set the cache directory
469	* - command: "dir <name>"
470	*/
471	static int cachefiles_daemon_dir(struct cachefiles_cache cache, char args)
472	{
473	char *dir;
474
475	_enter(",%s", args);
476
477	if (!*args) {
6ff66ac7	478	pr_err("Empty directory specified\n");
9ae326a6 DH	479	return -EINVAL;
	480	}
	481
	482	if (cache->rootdirname) {
6ff66ac7	483	pr_err("Second cache directory specified\n");
9ae326a6 DH	484	return -EEXIST;
	485	}
	486
	487	dir = kstrdup(args, GFP_KERNEL);
	488	if (!dir)
	489	return -ENOMEM;
	490
	491	cache->rootdirname = dir;
	492	return 0;
	493	}
	494
	495	/*
	496	* set the cache security context
	497	* - command: "secctx <ctx>"
	498	*/
	499	static int cachefiles_daemon_secctx(struct cachefiles_cache cache, char args)
	500	{
	501	char *secctx;
	502
	503	_enter(",%s", args);
	504
	505	if (!*args) {
6ff66ac7	506	pr_err("Empty security context specified\n");
9ae326a6 DH	507	return -EINVAL;
	508	}
	509
	510	if (cache->secctx) {
6ff66ac7	511	pr_err("Second security context specified\n");
9ae326a6 DH	512	return -EINVAL;
	513	}
	514
	515	secctx = kstrdup(args, GFP_KERNEL);
	516	if (!secctx)
	517	return -ENOMEM;
	518
	519	cache->secctx = secctx;
	520	return 0;
	521	}
	522
	523	/*
	524	* set the cache tag
	525	* - command: "tag <name>"
	526	*/
	527	static int cachefiles_daemon_tag(struct cachefiles_cache cache, char args)
	528	{
	529	char *tag;
	530
	531	_enter(",%s", args);
	532
	533	if (!*args) {
6ff66ac7	534	pr_err("Empty tag specified\n");
9ae326a6 DH	535	return -EINVAL;
	536	}
	537
	538	if (cache->tag)
	539	return -EEXIST;
	540
	541	tag = kstrdup(args, GFP_KERNEL);
	542	if (!tag)
	543	return -ENOMEM;
	544
	545	cache->tag = tag;
	546	return 0;
	547	}
	548
	549	/*
	550	* request a node in the cache be culled from the current working directory
	551	* - command: "cull <name>"
	552	*/
	553	static int cachefiles_daemon_cull(struct cachefiles_cache cache, char args)
	554	{
542ce7a9	555	struct path path;
9ae326a6 DH	556	const struct cred *saved_cred;
	557	int ret;
	558
	559	_enter(",%s", args);
	560
	561	if (strchr(args, '/'))
	562	goto inval;
	563
	564	if (!test_bit(CACHEFILES_READY, &cache->flags)) {
6ff66ac7	565	pr_err("cull applied to unready cache\n");
9ae326a6 DH	566	return -EIO;
	567	}
	568
	569	if (test_bit(CACHEFILES_DEAD, &cache->flags)) {
6ff66ac7	570	pr_err("cull applied to dead cache\n");
9ae326a6 DH	571	return -EIO;
	572	}
	573
	574	/* extract the directory dentry from the cwd */
f7ad3c6b	575	get_fs_pwd(current->fs, &path);
9ae326a6	576
542ce7a9	577	if (!S_ISDIR(path.dentry->d_inode->i_mode))
9ae326a6 DH	578	goto notdir;
	579
	580	cachefiles_begin_secure(cache, &saved_cred);
542ce7a9	581	ret = cachefiles_cull(cache, path.dentry, args);
9ae326a6 DH	582	cachefiles_end_secure(cache, saved_cred);
9ae326a6 DH	583
542ce7a9	584	path_put(&path);
9ae326a6 DH	585	_leave(" = %d", ret);
	586	return ret;
	587
	588	notdir:
542ce7a9	589	path_put(&path);
6ff66ac7	590	pr_err("cull command requires dirfd to be a directory\n");
9ae326a6 DH	591	return -ENOTDIR;
	592
	593	inval:
6ff66ac7	594	pr_err("cull command requires dirfd and filename\n");
9ae326a6 DH	595	return -EINVAL;
	596	}
	597
	598	/*
	599	* set debugging mode
	600	* - command: "debug <mask>"
	601	*/
	602	static int cachefiles_daemon_debug(struct cachefiles_cache cache, char args)
	603	{
	604	unsigned long mask;
	605
	606	_enter(",%s", args);
	607
	608	mask = simple_strtoul(args, &args, 0);
	609	if (args[0] != '\0')
	610	goto inval;
	611
	612	cachefiles_debug = mask;
	613	_leave(" = 0");
	614	return 0;
	615
	616	inval:
6ff66ac7	617	pr_err("debug command requires mask\n");
9ae326a6 DH	618	return -EINVAL;
	619	}
	620
	621	/*
	622	* find out whether an object in the current working directory is in use or not
	623	* - command: "inuse <name>"
	624	*/
	625	static int cachefiles_daemon_inuse(struct cachefiles_cache cache, char args)
	626	{
542ce7a9	627	struct path path;
9ae326a6 DH	628	const struct cred *saved_cred;
	629	int ret;
	630
	631	//_enter(",%s", args);
	632
	633	if (strchr(args, '/'))
	634	goto inval;
	635
	636	if (!test_bit(CACHEFILES_READY, &cache->flags)) {
6ff66ac7	637	pr_err("inuse applied to unready cache\n");
9ae326a6 DH	638	return -EIO;
	639	}
	640
	641	if (test_bit(CACHEFILES_DEAD, &cache->flags)) {
6ff66ac7	642	pr_err("inuse applied to dead cache\n");
9ae326a6 DH	643	return -EIO;
	644	}
	645
	646	/* extract the directory dentry from the cwd */
f7ad3c6b	647	get_fs_pwd(current->fs, &path);
9ae326a6	648
542ce7a9	649	if (!S_ISDIR(path.dentry->d_inode->i_mode))
9ae326a6 DH	650	goto notdir;
	651
	652	cachefiles_begin_secure(cache, &saved_cred);
542ce7a9	653	ret = cachefiles_check_in_use(cache, path.dentry, args);
9ae326a6 DH	654	cachefiles_end_secure(cache, saved_cred);
9ae326a6 DH	655
542ce7a9	656	path_put(&path);
9ae326a6 DH	657	//_leave(" = %d", ret);
	658	return ret;
	659
	660	notdir:
542ce7a9	661	path_put(&path);
6ff66ac7	662	pr_err("inuse command requires dirfd to be a directory\n");
9ae326a6 DH	663	return -ENOTDIR;
	664
	665	inval:
6ff66ac7	666	pr_err("inuse command requires dirfd and filename\n");
9ae326a6 DH	667	return -EINVAL;
	668	}
	669
	670	/*
	671	* see if we have space for a number of pages and/or a number of files in the
	672	* cache
	673	*/
	674	int cachefiles_has_space(struct cachefiles_cache *cache,
	675	unsigned fnr, unsigned bnr)
	676	{
	677	struct kstatfs stats;
ebabe9a9 CH	678	struct path path = {
	679	.mnt = cache->mnt,
	680	.dentry = cache->mnt->mnt_root,
	681	};
9ae326a6 DH	682	int ret;
	683
	684	//_enter("{%llu,%llu,%llu,%llu,%llu,%llu},%u,%u",
	685	// (unsigned long long) cache->frun,
	686	// (unsigned long long) cache->fcull,
	687	// (unsigned long long) cache->fstop,
	688	// (unsigned long long) cache->brun,
	689	// (unsigned long long) cache->bcull,
	690	// (unsigned long long) cache->bstop,
	691	// fnr, bnr);
	692
	693	/* find out how many pages of blockdev are available */
	694	memset(&stats, 0, sizeof(stats));
	695
ebabe9a9	696	ret = vfs_statfs(&path, &stats);
9ae326a6 DH	697	if (ret < 0) {
	698	if (ret == -EIO)
	699	cachefiles_io_error(cache, "statfs failed");
	700	_leave(" = %d", ret);
	701	return ret;
	702	}
	703
	704	stats.f_bavail >>= cache->bshift;
	705
	706	//_debug("avail %llu,%llu",
	707	// (unsigned long long) stats.f_ffree,
	708	// (unsigned long long) stats.f_bavail);
	709
	710	/* see if there is sufficient space */
	711	if (stats.f_ffree > fnr)
	712	stats.f_ffree -= fnr;
	713	else
	714	stats.f_ffree = 0;
	715
	716	if (stats.f_bavail > bnr)
	717	stats.f_bavail -= bnr;
	718	else
	719	stats.f_bavail = 0;
	720
	721	ret = -ENOBUFS;
	722	if (stats.f_ffree < cache->fstop \|\|
	723	stats.f_bavail < cache->bstop)
	724	goto begin_cull;
	725
	726	ret = 0;
	727	if (stats.f_ffree < cache->fcull \|\|
	728	stats.f_bavail < cache->bcull)
	729	goto begin_cull;
	730
	731	if (test_bit(CACHEFILES_CULLING, &cache->flags) &&
	732	stats.f_ffree >= cache->frun &&
	733	stats.f_bavail >= cache->brun &&
	734	test_and_clear_bit(CACHEFILES_CULLING, &cache->flags)
	735	) {
	736	_debug("cease culling");
	737	cachefiles_state_changed(cache);
	738	}
	739
	740	//_leave(" = 0");
	741	return 0;
	742
	743	begin_cull:
	744	if (!test_and_set_bit(CACHEFILES_CULLING, &cache->flags)) {
	745	_debug("### CULL CACHE ###");
	746	cachefiles_state_changed(cache);
	747	}
	748
	749	_leave(" = %d", ret);
	750	return ret;
	751	}