cache.c

Linux Kernel 2.6.9 for OMAP1710

	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);
			cd->cache_put(rq->item, cd);
			kfree(rq->buf);
			kfree(rq);
		} else
			spin_unlock(&queue_lock);
	}
	if (err == -EAGAIN)
		goto again;
	up(&queue_io_sem);
	return err ? err :  count;
}

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

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_dentry->d_inode)->data;

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

	down(&queue_io_sem);

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

	up(&queue_io_sem);
	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_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 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)
				break;
			list_del(&cr->q.list);
			spin_unlock(&queue_lock);
			detail->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;
}

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\n",
			   cp->expiry_time, atomic_read(&cp->refcnt));
	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);
}

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)
{
	int res;
	struct handle *han;
	struct cache_detail *cd = PDE(inode)->data;

	han = kmalloc(sizeof(*han), GFP_KERNEL);
	if (han == NULL)
		return -ENOMEM;

	han->cd = cd;

	res = seq_open(file, &cache_content_op);
	if (res)
		kfree(han);
	else
		((struct seq_file *)file->private_data)->private = han;

	return res;
}
static int content_release(struct inode *inode, struct file *file)
{
	struct seq_file *m = (struct seq_file *)file->private_data;
	struct handle *han = m->private;
	kfree(han);
	m->private = NULL;
	return seq_release(inode, file);
}

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

static ssize_t read_flush(struct file *file, char __user *buf,
			    size_t count, loff_t *ppos)
{
	struct cache_detail *cd = PDE(file->f_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_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 struct file_operations cache_flush_operations = {
	.open		= nonseekable_open,
	.read		= read_flush,
	.write		= write_flush,
};