cregit-Linux how code gets into the kernel

Release 4.11 fs/cachefiles/daemon.c

Directory: fs/cachefiles
/* 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; }

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David Howells167100.00%1100.00%
Total167100.00%1100.00%

/* * 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; }

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David Howells90100.00%1100.00%
Total90100.00%1100.00%

/* * 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; }

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David Howells235100.00%2100.00%
Total235100.00%2100.00%

/* * 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; }

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David Howells31296.30%133.33%
Al Viro82.47%133.33%
André Goddard Rosa41.23%133.33%
Total324100.00%3100.00%

/* * 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; }

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David Howells81100.00%1100.00%
Total81100.00%1100.00%

/* * 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; }

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David Howells2291.67%133.33%
Fabian Frederick28.33%266.67%
Total24100.00%3100.00%

/* * 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; }

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David Howells97100.00%1100.00%
Total97100.00%1100.00%

/* * 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; }

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David Howells99100.00%1100.00%
Total99100.00%1100.00%

/* * 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; }

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David Howells97100.00%1100.00%
Total97100.00%1100.00%

/* * 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; }

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David Howells97100.00%1100.00%
Total97100.00%1100.00%

/* * 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; }

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David Howells99100.00%1100.00%
Total99100.00%1100.00%

/* * 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; }

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David Howells97100.00%1100.00%
Total97100.00%1100.00%

/* * 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; }

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David Howells8395.40%133.33%
Fabian Frederick44.60%266.67%
Total87100.00%3100.00%

/* * 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; }

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David Howells8395.40%133.33%
Fabian Frederick44.60%266.67%
Total87100.00%3100.00%

/* * 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; }

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David Howells7897.50%133.33%
Fabian Frederick22.50%266.67%
Total80100.00%3100.00%

/* * 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; }

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David Howells16385.79%233.33%
Miklos Szeredi1910.00%233.33%
Fabian Frederick84.21%233.33%
Total190100.00%6100.00%

/* * 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; }

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David Howells7197.26%133.33%
Fabian Frederick22.74%266.67%
Total73100.00%3100.00%

/* * 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; }

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David Howells15184.83%233.33%
Miklos Szeredi1910.67%233.33%
Fabian Frederick84.49%233.33%
Total178100.00%6100.00%

/* * 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);