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linux/fs/cachefiles/daemon.c
Linus Torvalds a9a08845e9 vfs: do bulk POLL* -> EPOLL* replacement 
This is the mindless scripted replacement of kernel use of POLL*
variables as described by Al, done by this script:

    for V in IN OUT PRI ERR RDNORM RDBAND WRNORM WRBAND HUP RDHUP NVAL MSG; do
        L=`git grep -l -w POLL$V | grep -v '^t' | grep -v /um/ | grep -v '^sa' | grep -v '/poll.h$'|grep -v '^D'`
        for f in $L; do sed -i "-es/^\([^\"]*\)\(\<POLL$V\>\)/\\1E\\2/" $f; done
    done

with de-mangling cleanups yet to come.

NOTE! On almost all architectures, the EPOLL* constants have the same
values as the POLL* constants do.  But they keyword here is "almost".
For various bad reasons they aren't the same, and epoll() doesn't
actually work quite correctly in some cases due to this on Sparc et al.

The next patch from Al will sort out the final differences, and we
should be all done.

Scripted-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-02-11 14:34:03 -08:00

753 lines
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/* 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 __poll_t 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;
unsigned long long b_released;
unsigned f_released;
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 */
f_released = atomic_xchg(&cache->f_released, 0);
b_released = atomic_long_xchg(&cache->b_released, 0);
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"
" freleased=%x"
" breleased=%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,
f_released,
b_released);
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 = memdup_user_nul(_data, datalen);
if (IS_ERR(data))
return PTR_ERR(data);
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 EPOLLOUT to indicate culling state
*/
static __poll_t cachefiles_daemon_poll(struct file *file,
struct poll_table_struct *poll)
{
struct cachefiles_cache *cache = file->private_data;
__poll_t mask;
poll_wait(file, &cache->daemon_pollwq, poll);
mask = 0;
if (test_bit(CACHEFILES_STATE_CHANGED, &cache->flags))
mask |= EPOLLIN;
if (test_bit(CACHEFILES_CULLING, &cache->flags))
mask |= EPOLLOUT;
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 (!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;
}
/* extract the directory dentry from the cwd */
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;
}
/*
* 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;
}
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