--- /dev/null
+/* cf-proc.c: /proc/fs/cachefiles interface
+ *
+ * Copyright (C) 2006 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 License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, 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/mount.h>
+#include <linux/namespace.h>
+#include <linux/statfs.h>
+#include <linux/proc_fs.h>
+#include <linux/ctype.h>
+#include "internal.h"
+
+static int cachefiles_proc_open(struct inode *, struct file *);
+static int cachefiles_proc_release(struct inode *, struct file *);
+static ssize_t cachefiles_proc_read(struct file *, char __user *, size_t, loff_t *);
+static ssize_t cachefiles_proc_write(struct file *, const char __user *, size_t, loff_t *);
+static int cachefiles_proc_brun(struct cachefiles_cache *cache, char *args);
+static int cachefiles_proc_bcull(struct cachefiles_cache *cache, char *args);
+static int cachefiles_proc_bstop(struct cachefiles_cache *cache, char *args);
+static int cachefiles_proc_cull(struct cachefiles_cache *cache, char *args);
+static int cachefiles_proc_debug(struct cachefiles_cache *cache, char *args);
+static int cachefiles_proc_dir(struct cachefiles_cache *cache, char *args);
+static int cachefiles_proc_tag(struct cachefiles_cache *cache, char *args);
+
+struct proc_dir_entry *cachefiles_proc;
+
+static unsigned long cachefiles_open;
+
+struct file_operations cachefiles_proc_fops = {
+ .open = cachefiles_proc_open,
+ .release = cachefiles_proc_release,
+ .read = cachefiles_proc_read,
+ .write = cachefiles_proc_write,
+};
+
+struct cachefiles_proc_cmd {
+ char name[8];
+ int (*handler)(struct cachefiles_cache *cache, char *args);
+};
+
+static const struct cachefiles_proc_cmd cachefiles_proc_cmds[] = {
+ { "bind", cachefiles_proc_bind },
+ { "brun", cachefiles_proc_brun },
+ { "bcull", cachefiles_proc_bcull },
+ { "bstop", cachefiles_proc_bstop },
+ { "cull", cachefiles_proc_cull },
+ { "debug", cachefiles_proc_debug },
+ { "dir", cachefiles_proc_dir },
+ { "tag", cachefiles_proc_tag },
+ { "", NULL }
+};
+
+
+/*****************************************************************************/
+/*
+ * do various checks
+ */
+static int cachefiles_proc_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;
+
+ /* /proc/fs/cachefiles 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;
+ }
+
+ cache->active_nodes = RB_ROOT;
+ rwlock_init(&cache->active_lock);
+
+ /* set default caching limits
+ * - limit at 1% free space
+ * - cull below 5% free space
+ * - cease culling above 7% free space
+ */
+ 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_proc_release(struct inode *inode, struct file *file)
+{
+ struct cachefiles_cache *cache = file->private_data;
+
+ _enter("");
+
+ ASSERT(cache);
+
+ set_bit(CACHEFILES_DEAD, &cache->flags);
+
+ cachefiles_proc_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_proc_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);
+
+ /* summarise */
+ n = snprintf(buffer, sizeof(buffer),
+ "cull=%c"
+ " brun=%llx"
+ " bcull=%llx"
+ " bstop=%llx",
+ test_bit(CACHEFILES_CULLING, &cache->flags) ? '1' : '0',
+ cache->brun,
+ cache->bcull,
+ 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_proc_write(struct file *file,
+ const char __user *_data, size_t datalen,
+ loff_t *pos)
+{
+ const struct cachefiles_proc_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';
+ for (args++; isspace(*args); args++)
+ continue;
+ }
+
+ /* run the appropriate command handler */
+ for (cmd = cachefiles_proc_cmds; cmd->name[0]; cmd++)
+ if (strcmp(cmd->name, data) == 0)
+ goto found_command;
+
+error:
+ kfree(data);
+ _leave(" = %d", ret);
+ return ret;
+
+found_command:
+ mutex_lock(&file->f_dentry->d_inode->i_mutex);
+
+ ret = -EIO;
+ if (!test_bit(CACHEFILES_DEAD, &cache->flags))
+ ret = cmd->handler(cache, args);
+
+ mutex_unlock(&file->f_dentry->d_inode->i_mutex);
+
+ if (ret == 0)
+ ret = datalen;
+ goto error;
+}
+
+/*****************************************************************************/
+/*
+ * give a range error for cache space constraints
+ * - can be tail-called
+ */
+static int cachefiles_proc_range_error(struct cachefiles_cache *cache, char *args)
+{
+ kerror("Free space limits must be in range"
+ " 0%%<=bstop<bcull<brun<100%%");
+
+ return -EINVAL;
+}
+
+/*****************************************************************************/
+/*
+ * set the percentage of blocks at which to stop culling
+ * - command: "brun <N>%"
+ */
+static int cachefiles_proc_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_proc_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_proc_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_proc_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_proc_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_proc_range_error(cache, args);
+
+ cache->bstop_percent = bstop;
+ return 0;
+}
+
+/*****************************************************************************/
+/*
+ * set the cache directory
+ * - command: "dir <name>"
+ */
+static int cachefiles_proc_dir(struct cachefiles_cache *cache, char *args)
+{
+ char *dir;
+
+ _enter(",%s", args);
+
+ if (!*args) {
+ kerror("Empty directory specified");
+ return -EINVAL;
+ }
+
+ if (cache->rootdirname) {
+ kerror("Second cache directory specified");
+ return -EEXIST;
+ }
+
+ dir = kstrdup(args, GFP_KERNEL);
+ if (!dir)
+ return -ENOMEM;
+
+ cache->rootdirname = dir;
+ return 0;
+}
+
+/*****************************************************************************/
+/*
+ * set the cache tag
+ * - command: "tag <name>"
+ */
+static int cachefiles_proc_tag(struct cachefiles_cache *cache, char *args)
+{
+ char *tag;
+
+ _enter(",%s", args);
+
+ if (!*args) {
+ kerror("Empty tag specified");
+ 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
+ * - command: "cull <dirfd> <name>"
+ */
+static int cachefiles_proc_cull(struct cachefiles_cache *cache, char *args)
+{
+ struct dentry *dir;
+ struct file *dirfile;
+ int dirfd, fput_needed, ret;
+
+ _enter(",%s", args);
+
+ dirfd = simple_strtoul(args, &args, 0);
+
+ if (!args || !isspace(*args))
+ goto inval;
+
+ while (isspace(*args))
+ args++;
+
+ if (!*args)
+ goto inval;
+
+ if (strchr(args, '/'))
+ goto inval;
+
+ if (!test_bit(CACHEFILES_READY, &cache->flags)) {
+ kerror("cull applied to unready cache");
+ return -EIO;
+ }
+
+ if (test_bit(CACHEFILES_DEAD, &cache->flags)) {
+ kerror("cull applied to dead cache");
+ return -EIO;
+ }
+
+ /* extract the directory dentry from the fd */
+ dirfile = fget_light(dirfd, &fput_needed);
+ if (!dirfile) {
+ kerror("cull dirfd not open");
+ return -EBADF;
+ }
+
+ dir = dget(dirfile->f_dentry);
+ fput_light(dirfile, fput_needed);
+ dirfile = NULL;
+
+ if (!S_ISDIR(dir->d_inode->i_mode))
+ goto notdir;
+
+ ret = cachefiles_cull(cache, dir, args);
+
+ dput(dir);
+ _leave(" = %d", ret);
+ return ret;
+
+notdir:
+ dput(dir);
+ kerror("cull command requires dirfd to be a directory");
+ return -ENOTDIR;
+
+inval:
+ kerror("cull command requires dirfd and filename");
+ return -EINVAL;
+}
+
+/*****************************************************************************/
+/*
+ * set debugging mode
+ * - command: "debug <mask>"
+ */
+static int cachefiles_proc_debug(struct cachefiles_cache *cache, char *args)
+{
+ unsigned long mask;
+
+ _enter(",%s", args);
+
+ mask = simple_strtoul(args, &args, 0);
+
+ if (!args || !isspace(*args))
+ goto inval;
+
+ cachefiles_debug = mask;
+ _leave(" = 0");
+ return 0;
+
+inval:
+ kerror("debug command requires mask");
+ return -EINVAL;
+}
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