1 files changed, 755 insertions, 0 deletions

diff --git a/fs/cachefiles/daemon.c b/fs/cachefiles/daemon.c
new file mode 100644
index 000000000000..4618516dd994
--- /dev/null
+++ b/fs/cachefiles/daemon.c
@@ -0,0 +1,755 @@
+/* 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/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,
+};
+
+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';
+                for (args++; isspace(*args); args++)
+                        continue;
+        }
+
+        /* 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)
+{
+        kerror("Free space limits must be in range"
+               " 0%%<=stop<cull<run<100%%");
+
+        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) {
+                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 security context
+ * - command: "secctx <ctx>"
+ */
+static int cachefiles_daemon_secctx(struct cachefiles_cache *cache, char *args)
+{
+        char *secctx;
+
+        _enter(",%s", args);
+
+        if (!*args) {
+                kerror("Empty security context specified");
+                return -EINVAL;
+        }
+
+        if (cache->secctx) {
+                kerror("Second security context specified");
+                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) {
+                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 from the current working directory
+ * - command: "cull <name>"
+ */
+static int cachefiles_daemon_cull(struct cachefiles_cache *cache, char *args)
+{
+        struct fs_struct *fs;
+        struct dentry *dir;
+        const struct cred *saved_cred;
+        int ret;
+
+        _enter(",%s", args);
+
+        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 cwd */
+        fs = current->fs;
+        read_lock(&fs->lock);
+        dir = dget(fs->pwd.dentry);
+        read_unlock(&fs->lock);
+
+        if (!S_ISDIR(dir->d_inode->i_mode))
+                goto notdir;
+
+        cachefiles_begin_secure(cache, &saved_cred);
+        ret = cachefiles_cull(cache, dir, args);
+        cachefiles_end_secure(cache, saved_cred);
+
+        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_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:
+        kerror("debug command requires mask");
+        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 fs_struct *fs;
+        struct dentry *dir;
+        const struct cred *saved_cred;
+        int ret;
+
+        //_enter(",%s", args);
+
+        if (strchr(args, '/'))
+                goto inval;
+
+        if (!test_bit(CACHEFILES_READY, &cache->flags)) {
+                kerror("inuse applied to unready cache");
+                return -EIO;
+        }
+
+        if (test_bit(CACHEFILES_DEAD, &cache->flags)) {
+                kerror("inuse applied to dead cache");
+                return -EIO;
+        }
+
+        /* extract the directory dentry from the cwd */
+        fs = current->fs;
+        read_lock(&fs->lock);
+        dir = dget(fs->pwd.dentry);
+        read_unlock(&fs->lock);
+
+        if (!S_ISDIR(dir->d_inode->i_mode))
+                goto notdir;
+
+        cachefiles_begin_secure(cache, &saved_cred);
+        ret = cachefiles_check_in_use(cache, dir, args);
+        cachefiles_end_secure(cache, saved_cred);
+
+        dput(dir);
+        //_leave(" = %d", ret);
+        return ret;
+
+notdir:
+        dput(dir);
+        kerror("inuse command requires dirfd to be a directory");
+        return -ENOTDIR;
+
+inval:
+        kerror("inuse command requires dirfd and filename");
+        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;
+        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(cache->mnt->mnt_root, &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;
+}