Logo Search packages:      
Sourcecode: linux version File versions  Download package

cache.c

/*
 * net/sunrpc/cache.c
 *
 * Generic code for various authentication-related caches
 * used by sunrpc clients and servers.
 *
 * Copyright (C) 2002 Neil Brown <neilb@cse.unsw.edu.au>
 *
 * Released under terms in GPL version 2.  See COPYING.
 *
 */

#include <linux/types.h>
#include <linux/fs.h>
#include <linux/file.h>
#include <linux/slab.h>
#include <linux/signal.h>
#include <linux/sched.h>
#include <linux/kmod.h>
#include <linux/list.h>
#include <linux/module.h>
#include <linux/ctype.h>
#include <asm/uaccess.h>
#include <linux/poll.h>
#include <linux/seq_file.h>
#include <linux/proc_fs.h>
#include <linux/net.h>
#include <linux/workqueue.h>
#include <linux/mutex.h>
#include <asm/ioctls.h>
#include <linux/sunrpc/types.h>
#include <linux/sunrpc/cache.h>
#include <linux/sunrpc/stats.h>

#define      RPCDBG_FACILITY RPCDBG_CACHE

static int cache_defer_req(struct cache_req *req, struct cache_head *item);
static void cache_revisit_request(struct cache_head *item);

static void cache_init(struct cache_head *h)
{
      time_t now = get_seconds();
      h->next = NULL;
      h->flags = 0;
      kref_init(&h->ref);
      h->expiry_time = now + CACHE_NEW_EXPIRY;
      h->last_refresh = now;
}

struct cache_head *sunrpc_cache_lookup(struct cache_detail *detail,
                               struct cache_head *key, int hash)
{
      struct cache_head **head,  **hp;
      struct cache_head *new = NULL;

      head = &detail->hash_table[hash];

      read_lock(&detail->hash_lock);

      for (hp=head; *hp != NULL ; hp = &(*hp)->next) {
            struct cache_head *tmp = *hp;
            if (detail->match(tmp, key)) {
                  cache_get(tmp);
                  read_unlock(&detail->hash_lock);
                  return tmp;
            }
      }
      read_unlock(&detail->hash_lock);
      /* Didn't find anything, insert an empty entry */

      new = detail->alloc();
      if (!new)
            return NULL;
      /* must fully initialise 'new', else
       * we might get lose if we need to
       * cache_put it soon.
       */
      cache_init(new);
      detail->init(new, key);

      write_lock(&detail->hash_lock);

      /* check if entry appeared while we slept */
      for (hp=head; *hp != NULL ; hp = &(*hp)->next) {
            struct cache_head *tmp = *hp;
            if (detail->match(tmp, key)) {
                  cache_get(tmp);
                  write_unlock(&detail->hash_lock);
                  cache_put(new, detail);
                  return tmp;
            }
      }
      new->next = *head;
      *head = new;
      detail->entries++;
      cache_get(new);
      write_unlock(&detail->hash_lock);

      return new;
}
EXPORT_SYMBOL(sunrpc_cache_lookup);


static void queue_loose(struct cache_detail *detail, struct cache_head *ch);

static int cache_fresh_locked(struct cache_head *head, time_t expiry)
{
      head->expiry_time = expiry;
      head->last_refresh = get_seconds();
      return !test_and_set_bit(CACHE_VALID, &head->flags);
}

static void cache_fresh_unlocked(struct cache_head *head,
                  struct cache_detail *detail, int new)
{
      if (new)
            cache_revisit_request(head);
      if (test_and_clear_bit(CACHE_PENDING, &head->flags)) {
            cache_revisit_request(head);
            queue_loose(detail, head);
      }
}

struct cache_head *sunrpc_cache_update(struct cache_detail *detail,
                               struct cache_head *new, struct cache_head *old, int hash)
{
      /* The 'old' entry is to be replaced by 'new'.
       * If 'old' is not VALID, we update it directly,
       * otherwise we need to replace it
       */
      struct cache_head **head;
      struct cache_head *tmp;
      int is_new;

      if (!test_bit(CACHE_VALID, &old->flags)) {
            write_lock(&detail->hash_lock);
            if (!test_bit(CACHE_VALID, &old->flags)) {
                  if (test_bit(CACHE_NEGATIVE, &new->flags))
                        set_bit(CACHE_NEGATIVE, &old->flags);
                  else
                        detail->update(old, new);
                  is_new = cache_fresh_locked(old, new->expiry_time);
                  write_unlock(&detail->hash_lock);
                  cache_fresh_unlocked(old, detail, is_new);
                  return old;
            }
            write_unlock(&detail->hash_lock);
      }
      /* We need to insert a new entry */
      tmp = detail->alloc();
      if (!tmp) {
            cache_put(old, detail);
            return NULL;
      }
      cache_init(tmp);
      detail->init(tmp, old);
      head = &detail->hash_table[hash];

      write_lock(&detail->hash_lock);
      if (test_bit(CACHE_NEGATIVE, &new->flags))
            set_bit(CACHE_NEGATIVE, &tmp->flags);
      else
            detail->update(tmp, new);
      tmp->next = *head;
      *head = tmp;
      detail->entries++;
      cache_get(tmp);
      is_new = cache_fresh_locked(tmp, new->expiry_time);
      cache_fresh_locked(old, 0);
      write_unlock(&detail->hash_lock);
      cache_fresh_unlocked(tmp, detail, is_new);
      cache_fresh_unlocked(old, detail, 0);
      cache_put(old, detail);
      return tmp;
}
EXPORT_SYMBOL(sunrpc_cache_update);

static int cache_make_upcall(struct cache_detail *detail, struct cache_head *h);
/*
 * This is the generic cache management routine for all
 * the authentication caches.
 * It checks the currency of a cache item and will (later)
 * initiate an upcall to fill it if needed.
 *
 *
 * Returns 0 if the cache_head can be used, or cache_puts it and returns
 * -EAGAIN if upcall is pending,
 * -ETIMEDOUT if upcall failed and should be retried,
 * -ENOENT if cache entry was negative
 */
int cache_check(struct cache_detail *detail,
                struct cache_head *h, struct cache_req *rqstp)
{
      int rv;
      long refresh_age, age;

      /* First decide return status as best we can */
      if (!test_bit(CACHE_VALID, &h->flags) ||
          h->expiry_time < get_seconds())
            rv = -EAGAIN;
      else if (detail->flush_time > h->last_refresh)
            rv = -EAGAIN;
      else {
            /* entry is valid */
            if (test_bit(CACHE_NEGATIVE, &h->flags))
                  rv = -ENOENT;
            else rv = 0;
      }

      /* now see if we want to start an upcall */
      refresh_age = (h->expiry_time - h->last_refresh);
      age = get_seconds() - h->last_refresh;

      if (rqstp == NULL) {
            if (rv == -EAGAIN)
                  rv = -ENOENT;
      } else if (rv == -EAGAIN || age > refresh_age/2) {
            dprintk("RPC:       Want update, refage=%ld, age=%ld\n",
                        refresh_age, age);
            if (!test_and_set_bit(CACHE_PENDING, &h->flags)) {
                  switch (cache_make_upcall(detail, h)) {
                  case -EINVAL:
                        clear_bit(CACHE_PENDING, &h->flags);
                        if (rv == -EAGAIN) {
                              set_bit(CACHE_NEGATIVE, &h->flags);
                              cache_fresh_unlocked(h, detail,
                                   cache_fresh_locked(h, get_seconds()+CACHE_NEW_EXPIRY));
                              rv = -ENOENT;
                        }
                        break;

                  case -EAGAIN:
                        clear_bit(CACHE_PENDING, &h->flags);
                        cache_revisit_request(h);
                        break;
                  }
            }
      }

      if (rv == -EAGAIN)
            if (cache_defer_req(rqstp, h) != 0)
                  rv = -ETIMEDOUT;

      if (rv)
            cache_put(h, detail);
      return rv;
}

/*
 * caches need to be periodically cleaned.
 * For this we maintain a list of cache_detail and
 * a current pointer into that list and into the table
 * for that entry.
 *
 * Each time clean_cache is called it finds the next non-empty entry
 * in the current table and walks the list in that entry
 * looking for entries that can be removed.
 *
 * An entry gets removed if:
 * - The expiry is before current time
 * - The last_refresh time is before the flush_time for that cache
 *
 * later we might drop old entries with non-NEVER expiry if that table
 * is getting 'full' for some definition of 'full'
 *
 * The question of "how often to scan a table" is an interesting one
 * and is answered in part by the use of the "nextcheck" field in the
 * cache_detail.
 * When a scan of a table begins, the nextcheck field is set to a time
 * that is well into the future.
 * While scanning, if an expiry time is found that is earlier than the
 * current nextcheck time, nextcheck is set to that expiry time.
 * If the flush_time is ever set to a time earlier than the nextcheck
 * time, the nextcheck time is then set to that flush_time.
 *
 * A table is then only scanned if the current time is at least
 * the nextcheck time.
 *
 */

static LIST_HEAD(cache_list);
static DEFINE_SPINLOCK(cache_list_lock);
static struct cache_detail *current_detail;
static int current_index;

static const struct file_operations cache_file_operations;
static const struct file_operations content_file_operations;
static const struct file_operations cache_flush_operations;

static void do_cache_clean(struct work_struct *work);
static DECLARE_DELAYED_WORK(cache_cleaner, do_cache_clean);

void cache_register(struct cache_detail *cd)
{
      cd->proc_ent = proc_mkdir(cd->name, proc_net_rpc);
      if (cd->proc_ent) {
            struct proc_dir_entry *p;
            cd->proc_ent->owner = cd->owner;
            cd->channel_ent = cd->content_ent = NULL;

            p = create_proc_entry("flush", S_IFREG|S_IRUSR|S_IWUSR,
                              cd->proc_ent);
            cd->flush_ent =  p;
            if (p) {
                  p->proc_fops = &cache_flush_operations;
                  p->owner = cd->owner;
                  p->data = cd;
            }

            if (cd->cache_request || cd->cache_parse) {
                  p = create_proc_entry("channel", S_IFREG|S_IRUSR|S_IWUSR,
                                    cd->proc_ent);
                  cd->channel_ent = p;
                  if (p) {
                        p->proc_fops = &cache_file_operations;
                        p->owner = cd->owner;
                        p->data = cd;
                  }
            }
            if (cd->cache_show) {
                  p = create_proc_entry("content", S_IFREG|S_IRUSR|S_IWUSR,
                                    cd->proc_ent);
                  cd->content_ent = p;
                  if (p) {
                        p->proc_fops = &content_file_operations;
                        p->owner = cd->owner;
                        p->data = cd;
                  }
            }
      }
      rwlock_init(&cd->hash_lock);
      INIT_LIST_HEAD(&cd->queue);
      spin_lock(&cache_list_lock);
      cd->nextcheck = 0;
      cd->entries = 0;
      atomic_set(&cd->readers, 0);
      cd->last_close = 0;
      cd->last_warn = -1;
      list_add(&cd->others, &cache_list);
      spin_unlock(&cache_list_lock);

      /* start the cleaning process */
      schedule_delayed_work(&cache_cleaner, 0);
}

int cache_unregister(struct cache_detail *cd)
{
      cache_purge(cd);
      spin_lock(&cache_list_lock);
      write_lock(&cd->hash_lock);
      if (cd->entries || atomic_read(&cd->inuse)) {
            write_unlock(&cd->hash_lock);
            spin_unlock(&cache_list_lock);
            return -EBUSY;
      }
      if (current_detail == cd)
            current_detail = NULL;
      list_del_init(&cd->others);
      write_unlock(&cd->hash_lock);
      spin_unlock(&cache_list_lock);
      if (cd->proc_ent) {
            if (cd->flush_ent)
                  remove_proc_entry("flush", cd->proc_ent);
            if (cd->channel_ent)
                  remove_proc_entry("channel", cd->proc_ent);
            if (cd->content_ent)
                  remove_proc_entry("content", cd->proc_ent);

            cd->proc_ent = NULL;
            remove_proc_entry(cd->name, proc_net_rpc);
      }
      if (list_empty(&cache_list)) {
            /* module must be being unloaded so its safe to kill the worker */
            cancel_delayed_work_sync(&cache_cleaner);
      }
      return 0;
}

/* clean cache tries to find something to clean
 * and cleans it.
 * It returns 1 if it cleaned something,
 *            0 if it didn't find anything this time
 *           -1 if it fell off the end of the list.
 */
static int cache_clean(void)
{
      int rv = 0;
      struct list_head *next;

      spin_lock(&cache_list_lock);

      /* find a suitable table if we don't already have one */
      while (current_detail == NULL ||
          current_index >= current_detail->hash_size) {
            if (current_detail)
                  next = current_detail->others.next;
            else
                  next = cache_list.next;
            if (next == &cache_list) {
                  current_detail = NULL;
                  spin_unlock(&cache_list_lock);
                  return -1;
            }
            current_detail = list_entry(next, struct cache_detail, others);
            if (current_detail->nextcheck > get_seconds())
                  current_index = current_detail->hash_size;
            else {
                  current_index = 0;
                  current_detail->nextcheck = get_seconds()+30*60;
            }
      }

      /* find a non-empty bucket in the table */
      while (current_detail &&
             current_index < current_detail->hash_size &&
             current_detail->hash_table[current_index] == NULL)
            current_index++;

      /* find a cleanable entry in the bucket and clean it, or set to next bucket */

      if (current_detail && current_index < current_detail->hash_size) {
            struct cache_head *ch, **cp;
            struct cache_detail *d;

            write_lock(&current_detail->hash_lock);

            /* Ok, now to clean this strand */

            cp = & current_detail->hash_table[current_index];
            ch = *cp;
            for (; ch; cp= & ch->next, ch= *cp) {
                  if (current_detail->nextcheck > ch->expiry_time)
                        current_detail->nextcheck = ch->expiry_time+1;
                  if (ch->expiry_time >= get_seconds()
                      && ch->last_refresh >= current_detail->flush_time
                        )
                        continue;
                  if (test_and_clear_bit(CACHE_PENDING, &ch->flags))
                        queue_loose(current_detail, ch);

                  if (atomic_read(&ch->ref.refcount) == 1)
                        break;
            }
            if (ch) {
                  *cp = ch->next;
                  ch->next = NULL;
                  current_detail->entries--;
                  rv = 1;
            }
            write_unlock(&current_detail->hash_lock);
            d = current_detail;
            if (!ch)
                  current_index ++;
            spin_unlock(&cache_list_lock);
            if (ch)
                  cache_put(ch, d);
      } else
            spin_unlock(&cache_list_lock);

      return rv;
}

/*
 * We want to regularly clean the cache, so we need to schedule some work ...
 */
static void do_cache_clean(struct work_struct *work)
{
      int delay = 5;
      if (cache_clean() == -1)
            delay = 30*HZ;

      if (list_empty(&cache_list))
            delay = 0;

      if (delay)
            schedule_delayed_work(&cache_cleaner, delay);
}


/*
 * Clean all caches promptly.  This just calls cache_clean
 * repeatedly until we are sure that every cache has had a chance to
 * be fully cleaned
 */
void cache_flush(void)
{
      while (cache_clean() != -1)
            cond_resched();
      while (cache_clean() != -1)
            cond_resched();
}

void cache_purge(struct cache_detail *detail)
{
      detail->flush_time = LONG_MAX;
      detail->nextcheck = get_seconds();
      cache_flush();
      detail->flush_time = 1;
}



/*
 * Deferral and Revisiting of Requests.
 *
 * If a cache lookup finds a pending entry, we
 * need to defer the request and revisit it later.
 * All deferred requests are stored in a hash table,
 * indexed by "struct cache_head *".
 * As it may be wasteful to store a whole request
 * structure, we allow the request to provide a
 * deferred form, which must contain a
 * 'struct cache_deferred_req'
 * This cache_deferred_req contains a method to allow
 * it to be revisited when cache info is available
 */

#define     DFR_HASHSIZE      (PAGE_SIZE/sizeof(struct list_head))
#define     DFR_HASH(item)    ((((long)item)>>4 ^ (((long)item)>>13)) % DFR_HASHSIZE)

#define     DFR_MAX     300   /* ??? */

static DEFINE_SPINLOCK(cache_defer_lock);
static LIST_HEAD(cache_defer_list);
static struct list_head cache_defer_hash[DFR_HASHSIZE];
static int cache_defer_cnt;

static int cache_defer_req(struct cache_req *req, struct cache_head *item)
{
      struct cache_deferred_req *dreq;
      int hash = DFR_HASH(item);

      if (cache_defer_cnt >= DFR_MAX) {
            /* too much in the cache, randomly drop this one,
             * or continue and drop the oldest below
             */
            if (net_random()&1)
                  return -ETIMEDOUT;
      }
      dreq = req->defer(req);
      if (dreq == NULL)
            return -ETIMEDOUT;

      dreq->item = item;
      dreq->recv_time = get_seconds();

      spin_lock(&cache_defer_lock);

      list_add(&dreq->recent, &cache_defer_list);

      if (cache_defer_hash[hash].next == NULL)
            INIT_LIST_HEAD(&cache_defer_hash[hash]);
      list_add(&dreq->hash, &cache_defer_hash[hash]);

      /* it is in, now maybe clean up */
      dreq = NULL;
      if (++cache_defer_cnt > DFR_MAX) {
            dreq = list_entry(cache_defer_list.prev,
                          struct cache_deferred_req, recent);
            list_del(&dreq->recent);
            list_del(&dreq->hash);
            cache_defer_cnt--;
      }
      spin_unlock(&cache_defer_lock);

      if (dreq) {
            /* there was one too many */
            dreq->revisit(dreq, 1);
      }
      if (!test_bit(CACHE_PENDING, &item->flags)) {
            /* must have just been validated... */
            cache_revisit_request(item);
      }
      return 0;
}

static void cache_revisit_request(struct cache_head *item)
{
      struct cache_deferred_req *dreq;
      struct list_head pending;

      struct list_head *lp;
      int hash = DFR_HASH(item);

      INIT_LIST_HEAD(&pending);
      spin_lock(&cache_defer_lock);

      lp = cache_defer_hash[hash].next;
      if (lp) {
            while (lp != &cache_defer_hash[hash]) {
                  dreq = list_entry(lp, struct cache_deferred_req, hash);
                  lp = lp->next;
                  if (dreq->item == item) {
                        list_del(&dreq->hash);
                        list_move(&dreq->recent, &pending);
                        cache_defer_cnt--;
                  }
            }
      }
      spin_unlock(&cache_defer_lock);

      while (!list_empty(&pending)) {
            dreq = list_entry(pending.next, struct cache_deferred_req, recent);
            list_del_init(&dreq->recent);
            dreq->revisit(dreq, 0);
      }
}

void cache_clean_deferred(void *owner)
{
      struct cache_deferred_req *dreq, *tmp;
      struct list_head pending;


      INIT_LIST_HEAD(&pending);
      spin_lock(&cache_defer_lock);

      list_for_each_entry_safe(dreq, tmp, &cache_defer_list, recent) {
            if (dreq->owner == owner) {
                  list_del(&dreq->hash);
                  list_move(&dreq->recent, &pending);
                  cache_defer_cnt--;
            }
      }
      spin_unlock(&cache_defer_lock);

      while (!list_empty(&pending)) {
            dreq = list_entry(pending.next, struct cache_deferred_req, recent);
            list_del_init(&dreq->recent);
            dreq->revisit(dreq, 1);
      }
}

/*
 * communicate with user-space
 *
 * We have a magic /proc file - /proc/sunrpc/cache
 * On read, you get a full request, or block
 * On write, an update request is processed
 * Poll works if anything to read, and always allows write
 *
 * Implemented by linked list of requests.  Each open file has
 * a ->private that also exists in this list.  New request are added
 * to the end and may wakeup and preceding readers.
 * New readers are added to the head.  If, on read, an item is found with
 * CACHE_UPCALLING clear, we free it from the list.
 *
 */

static DEFINE_SPINLOCK(queue_lock);
static DEFINE_MUTEX(queue_io_mutex);

struct cache_queue {
      struct list_head  list;
      int               reader;     /* if 0, then request */
};
struct cache_request {
      struct cache_queue      q;
      struct cache_head *item;
      char              * buf;
      int               len;
      int               readers;
};
struct cache_reader {
      struct cache_queue      q;
      int               offset;     /* if non-0, we have a refcnt on next request */
};

static ssize_t
cache_read(struct file *filp, char __user *buf, size_t count, loff_t *ppos)
{
      struct cache_reader *rp = filp->private_data;
      struct cache_request *rq;
      struct cache_detail *cd = PDE(filp->f_path.dentry->d_inode)->data;
      int err;

      if (count == 0)
            return 0;

      mutex_lock(&queue_io_mutex); /* protect against multiple concurrent
                        * readers on this file */
 again:
      spin_lock(&queue_lock);
      /* need to find next request */
      while (rp->q.list.next != &cd->queue &&
             list_entry(rp->q.list.next, struct cache_queue, list)
             ->reader) {
            struct list_head *next = rp->q.list.next;
            list_move(&rp->q.list, next);
      }
      if (rp->q.list.next == &cd->queue) {
            spin_unlock(&queue_lock);
            mutex_unlock(&queue_io_mutex);
            BUG_ON(rp->offset);
            return 0;
      }
      rq = container_of(rp->q.list.next, struct cache_request, q.list);
      BUG_ON(rq->q.reader);
      if (rp->offset == 0)
            rq->readers++;
      spin_unlock(&queue_lock);

      if (rp->offset == 0 && !test_bit(CACHE_PENDING, &rq->item->flags)) {
            err = -EAGAIN;
            spin_lock(&queue_lock);
            list_move(&rp->q.list, &rq->q.list);
            spin_unlock(&queue_lock);
      } else {
            if (rp->offset + count > rq->len)
                  count = rq->len - rp->offset;
            err = -EFAULT;
            if (copy_to_user(buf, rq->buf + rp->offset, count))
                  goto out;
            rp->offset += count;
            if (rp->offset >= rq->len) {
                  rp->offset = 0;
                  spin_lock(&queue_lock);
                  list_move(&rp->q.list, &rq->q.list);
                  spin_unlock(&queue_lock);
            }
            err = 0;
      }
 out:
      if (rp->offset == 0) {
            /* need to release rq */
            spin_lock(&queue_lock);
            rq->readers--;
            if (rq->readers == 0 &&
                !test_bit(CACHE_PENDING, &rq->item->flags)) {
                  list_del(&rq->q.list);
                  spin_unlock(&queue_lock);
                  cache_put(rq->item, cd);
                  kfree(rq->buf);
                  kfree(rq);
            } else
                  spin_unlock(&queue_lock);
      }
      if (err == -EAGAIN)
            goto again;
      mutex_unlock(&queue_io_mutex);
      return err ? err :  count;
}

static char write_buf[8192]; /* protected by queue_io_mutex */

static ssize_t
cache_write(struct file *filp, const char __user *buf, size_t count,
          loff_t *ppos)
{
      int err;
      struct cache_detail *cd = PDE(filp->f_path.dentry->d_inode)->data;

      if (count == 0)
            return 0;
      if (count >= sizeof(write_buf))
            return -EINVAL;

      mutex_lock(&queue_io_mutex);

      if (copy_from_user(write_buf, buf, count)) {
            mutex_unlock(&queue_io_mutex);
            return -EFAULT;
      }
      write_buf[count] = '\0';
      if (cd->cache_parse)
            err = cd->cache_parse(cd, write_buf, count);
      else
            err = -EINVAL;

      mutex_unlock(&queue_io_mutex);
      return err ? err : count;
}

static DECLARE_WAIT_QUEUE_HEAD(queue_wait);

static unsigned int
cache_poll(struct file *filp, poll_table *wait)
{
      unsigned int mask;
      struct cache_reader *rp = filp->private_data;
      struct cache_queue *cq;
      struct cache_detail *cd = PDE(filp->f_path.dentry->d_inode)->data;

      poll_wait(filp, &queue_wait, wait);

      /* alway allow write */
      mask = POLL_OUT | POLLWRNORM;

      if (!rp)
            return mask;

      spin_lock(&queue_lock);

      for (cq= &rp->q; &cq->list != &cd->queue;
           cq = list_entry(cq->list.next, struct cache_queue, list))
            if (!cq->reader) {
                  mask |= POLLIN | POLLRDNORM;
                  break;
            }
      spin_unlock(&queue_lock);
      return mask;
}

static int
cache_ioctl(struct inode *ino, struct file *filp,
          unsigned int cmd, unsigned long arg)
{
      int len = 0;
      struct cache_reader *rp = filp->private_data;
      struct cache_queue *cq;
      struct cache_detail *cd = PDE(ino)->data;

      if (cmd != FIONREAD || !rp)
            return -EINVAL;

      spin_lock(&queue_lock);

      /* only find the length remaining in current request,
       * or the length of the next request
       */
      for (cq= &rp->q; &cq->list != &cd->queue;
           cq = list_entry(cq->list.next, struct cache_queue, list))
            if (!cq->reader) {
                  struct cache_request *cr =
                        container_of(cq, struct cache_request, q);
                  len = cr->len - rp->offset;
                  break;
            }
      spin_unlock(&queue_lock);

      return put_user(len, (int __user *)arg);
}

static int
cache_open(struct inode *inode, struct file *filp)
{
      struct cache_reader *rp = NULL;

      nonseekable_open(inode, filp);
      if (filp->f_mode & FMODE_READ) {
            struct cache_detail *cd = PDE(inode)->data;

            rp = kmalloc(sizeof(*rp), GFP_KERNEL);
            if (!rp)
                  return -ENOMEM;
            rp->offset = 0;
            rp->q.reader = 1;
            atomic_inc(&cd->readers);
            spin_lock(&queue_lock);
            list_add(&rp->q.list, &cd->queue);
            spin_unlock(&queue_lock);
      }
      filp->private_data = rp;
      return 0;
}

static int
cache_release(struct inode *inode, struct file *filp)
{
      struct cache_reader *rp = filp->private_data;
      struct cache_detail *cd = PDE(inode)->data;

      if (rp) {
            spin_lock(&queue_lock);
            if (rp->offset) {
                  struct cache_queue *cq;
                  for (cq= &rp->q; &cq->list != &cd->queue;
                       cq = list_entry(cq->list.next, struct cache_queue, list))
                        if (!cq->reader) {
                              container_of(cq, struct cache_request, q)
                                    ->readers--;
                              break;
                        }
                  rp->offset = 0;
            }
            list_del(&rp->q.list);
            spin_unlock(&queue_lock);

            filp->private_data = NULL;
            kfree(rp);

            cd->last_close = get_seconds();
            atomic_dec(&cd->readers);
      }
      return 0;
}



static const struct file_operations cache_file_operations = {
      .owner            = THIS_MODULE,
      .llseek           = no_llseek,
      .read       = cache_read,
      .write            = cache_write,
      .poll       = cache_poll,
      .ioctl            = cache_ioctl, /* for FIONREAD */
      .open       = cache_open,
      .release    = cache_release,
};


static void queue_loose(struct cache_detail *detail, struct cache_head *ch)
{
      struct cache_queue *cq;
      spin_lock(&queue_lock);
      list_for_each_entry(cq, &detail->queue, list)
            if (!cq->reader) {
                  struct cache_request *cr = container_of(cq, struct cache_request, q);
                  if (cr->item != ch)
                        continue;
                  if (cr->readers != 0)
                        continue;
                  list_del(&cr->q.list);
                  spin_unlock(&queue_lock);
                  cache_put(cr->item, detail);
                  kfree(cr->buf);
                  kfree(cr);
                  return;
            }
      spin_unlock(&queue_lock);
}

/*
 * Support routines for text-based upcalls.
 * Fields are separated by spaces.
 * Fields are either mangled to quote space tab newline slosh with slosh
 * or a hexified with a leading \x
 * Record is terminated with newline.
 *
 */

void qword_add(char **bpp, int *lp, char *str)
{
      char *bp = *bpp;
      int len = *lp;
      char c;

      if (len < 0) return;

      while ((c=*str++) && len)
            switch(c) {
            case ' ':
            case '\t':
            case '\n':
            case '\\':
                  if (len >= 4) {
                        *bp++ = '\\';
                        *bp++ = '0' + ((c & 0300)>>6);
                        *bp++ = '0' + ((c & 0070)>>3);
                        *bp++ = '0' + ((c & 0007)>>0);
                  }
                  len -= 4;
                  break;
            default:
                  *bp++ = c;
                  len--;
            }
      if (c || len <1) len = -1;
      else {
            *bp++ = ' ';
            len--;
      }
      *bpp = bp;
      *lp = len;
}

void qword_addhex(char **bpp, int *lp, char *buf, int blen)
{
      char *bp = *bpp;
      int len = *lp;

      if (len < 0) return;

      if (len > 2) {
            *bp++ = '\\';
            *bp++ = 'x';
            len -= 2;
            while (blen && len >= 2) {
                  unsigned char c = *buf++;
                  *bp++ = '0' + ((c&0xf0)>>4) + (c>=0xa0)*('a'-'9'-1);
                  *bp++ = '0' + (c&0x0f) + ((c&0x0f)>=0x0a)*('a'-'9'-1);
                  len -= 2;
                  blen--;
            }
      }
      if (blen || len<1) len = -1;
      else {
            *bp++ = ' ';
            len--;
      }
      *bpp = bp;
      *lp = len;
}

static void warn_no_listener(struct cache_detail *detail)
{
      if (detail->last_warn != detail->last_close) {
            detail->last_warn = detail->last_close;
            if (detail->warn_no_listener)
                  detail->warn_no_listener(detail);
      }
}

/*
 * register an upcall request to user-space.
 * Each request is at most one page long.
 */
static int cache_make_upcall(struct cache_detail *detail, struct cache_head *h)
{

      char *buf;
      struct cache_request *crq;
      char *bp;
      int len;

      if (detail->cache_request == NULL)
            return -EINVAL;

      if (atomic_read(&detail->readers) == 0 &&
          detail->last_close < get_seconds() - 30) {
                  warn_no_listener(detail);
                  return -EINVAL;
      }

      buf = kmalloc(PAGE_SIZE, GFP_KERNEL);
      if (!buf)
            return -EAGAIN;

      crq = kmalloc(sizeof (*crq), GFP_KERNEL);
      if (!crq) {
            kfree(buf);
            return -EAGAIN;
      }

      bp = buf; len = PAGE_SIZE;

      detail->cache_request(detail, h, &bp, &len);

      if (len < 0) {
            kfree(buf);
            kfree(crq);
            return -EAGAIN;
      }
      crq->q.reader = 0;
      crq->item = cache_get(h);
      crq->buf = buf;
      crq->len = PAGE_SIZE - len;
      crq->readers = 0;
      spin_lock(&queue_lock);
      list_add_tail(&crq->q.list, &detail->queue);
      spin_unlock(&queue_lock);
      wake_up(&queue_wait);
      return 0;
}

/*
 * parse a message from user-space and pass it
 * to an appropriate cache
 * Messages are, like requests, separated into fields by
 * spaces and dequotes as \xHEXSTRING or embedded \nnn octal
 *
 * Message is
 *   reply cachename expiry key ... content....
 *
 * key and content are both parsed by cache
 */

#define isodigit(c) (isdigit(c) && c <= '7')
int qword_get(char **bpp, char *dest, int bufsize)
{
      /* return bytes copied, or -1 on error */
      char *bp = *bpp;
      int len = 0;

      while (*bp == ' ') bp++;

      if (bp[0] == '\\' && bp[1] == 'x') {
            /* HEX STRING */
            bp += 2;
            while (isxdigit(bp[0]) && isxdigit(bp[1]) && len < bufsize) {
                  int byte = isdigit(*bp) ? *bp-'0' : toupper(*bp)-'A'+10;
                  bp++;
                  byte <<= 4;
                  byte |= isdigit(*bp) ? *bp-'0' : toupper(*bp)-'A'+10;
                  *dest++ = byte;
                  bp++;
                  len++;
            }
      } else {
            /* text with \nnn octal quoting */
            while (*bp != ' ' && *bp != '\n' && *bp && len < bufsize-1) {
                  if (*bp == '\\' &&
                      isodigit(bp[1]) && (bp[1] <= '3') &&
                      isodigit(bp[2]) &&
                      isodigit(bp[3])) {
                        int byte = (*++bp -'0');
                        bp++;
                        byte = (byte << 3) | (*bp++ - '0');
                        byte = (byte << 3) | (*bp++ - '0');
                        *dest++ = byte;
                        len++;
                  } else {
                        *dest++ = *bp++;
                        len++;
                  }
            }
      }

      if (*bp != ' ' && *bp != '\n' && *bp != '\0')
            return -1;
      while (*bp == ' ') bp++;
      *bpp = bp;
      *dest = '\0';
      return len;
}


/*
 * support /proc/sunrpc/cache/$CACHENAME/content
 * as a seqfile.
 * We call ->cache_show passing NULL for the item to
 * get a header, then pass each real item in the cache
 */

struct handle {
      struct cache_detail *cd;
};

static void *c_start(struct seq_file *m, loff_t *pos)
{
      loff_t n = *pos;
      unsigned hash, entry;
      struct cache_head *ch;
      struct cache_detail *cd = ((struct handle*)m->private)->cd;


      read_lock(&cd->hash_lock);
      if (!n--)
            return SEQ_START_TOKEN;
      hash = n >> 32;
      entry = n & ((1LL<<32) - 1);

      for (ch=cd->hash_table[hash]; ch; ch=ch->next)
            if (!entry--)
                  return ch;
      n &= ~((1LL<<32) - 1);
      do {
            hash++;
            n += 1LL<<32;
      } while(hash < cd->hash_size &&
            cd->hash_table[hash]==NULL);
      if (hash >= cd->hash_size)
            return NULL;
      *pos = n+1;
      return cd->hash_table[hash];
}

static void *c_next(struct seq_file *m, void *p, loff_t *pos)
{
      struct cache_head *ch = p;
      int hash = (*pos >> 32);
      struct cache_detail *cd = ((struct handle*)m->private)->cd;

      if (p == SEQ_START_TOKEN)
            hash = 0;
      else if (ch->next == NULL) {
            hash++;
            *pos += 1LL<<32;
      } else {
            ++*pos;
            return ch->next;
      }
      *pos &= ~((1LL<<32) - 1);
      while (hash < cd->hash_size &&
             cd->hash_table[hash] == NULL) {
            hash++;
            *pos += 1LL<<32;
      }
      if (hash >= cd->hash_size)
            return NULL;
      ++*pos;
      return cd->hash_table[hash];
}

static void c_stop(struct seq_file *m, void *p)
{
      struct cache_detail *cd = ((struct handle*)m->private)->cd;
      read_unlock(&cd->hash_lock);
}

static int c_show(struct seq_file *m, void *p)
{
      struct cache_head *cp = p;
      struct cache_detail *cd = ((struct handle*)m->private)->cd;

      if (p == SEQ_START_TOKEN)
            return cd->cache_show(m, cd, NULL);

      ifdebug(CACHE)
            seq_printf(m, "# expiry=%ld refcnt=%d flags=%lx\n",
                     cp->expiry_time, atomic_read(&cp->ref.refcount), cp->flags);
      cache_get(cp);
      if (cache_check(cd, cp, NULL))
            /* cache_check does a cache_put on failure */
            seq_printf(m, "# ");
      else
            cache_put(cp, cd);

      return cd->cache_show(m, cd, cp);
}

static const struct seq_operations cache_content_op = {
      .start      = c_start,
      .next = c_next,
      .stop = c_stop,
      .show = c_show,
};

static int content_open(struct inode *inode, struct file *file)
{
      struct handle *han;
      struct cache_detail *cd = PDE(inode)->data;

      han = __seq_open_private(file, &cache_content_op, sizeof(*han));
      if (han == NULL)
            return -ENOMEM;

      han->cd = cd;
      return 0;
}

static const struct file_operations content_file_operations = {
      .open       = content_open,
      .read       = seq_read,
      .llseek           = seq_lseek,
      .release    = seq_release_private,
};

static ssize_t read_flush(struct file *file, char __user *buf,
                      size_t count, loff_t *ppos)
{
      struct cache_detail *cd = PDE(file->f_path.dentry->d_inode)->data;
      char tbuf[20];
      unsigned long p = *ppos;
      int len;

      sprintf(tbuf, "%lu\n", cd->flush_time);
      len = strlen(tbuf);
      if (p >= len)
            return 0;
      len -= p;
      if (len > count) len = count;
      if (copy_to_user(buf, (void*)(tbuf+p), len))
            len = -EFAULT;
      else
            *ppos += len;
      return len;
}

static ssize_t write_flush(struct file * file, const char __user * buf,
                       size_t count, loff_t *ppos)
{
      struct cache_detail *cd = PDE(file->f_path.dentry->d_inode)->data;
      char tbuf[20];
      char *ep;
      long flushtime;
      if (*ppos || count > sizeof(tbuf)-1)
            return -EINVAL;
      if (copy_from_user(tbuf, buf, count))
            return -EFAULT;
      tbuf[count] = 0;
      flushtime = simple_strtoul(tbuf, &ep, 0);
      if (*ep && *ep != '\n')
            return -EINVAL;

      cd->flush_time = flushtime;
      cd->nextcheck = get_seconds();
      cache_flush();

      *ppos += count;
      return count;
}

static const struct file_operations cache_flush_operations = {
      .open       = nonseekable_open,
      .read       = read_flush,
      .write            = write_flush,
};

Generated by  Doxygen 1.6.0   Back to index