/*
 * (C) 2001 Clemson University and The University of Chicago
 *
 * See COPYING in top-level directory.
 */

#include "protocol.h"
#include "pvfs2-kernel.h"
#include "pvfs2-bufmap.h"

struct readdir_handle_s {
	int buffer_index;
	struct orangefs_readdir_response_s readdir_response;
	void *dents_buf;
};

/*
 * decode routine needed by kmod to make sense of the shared page for readdirs.
 */
static long decode_dirents(char *ptr, size_t size,
                           struct orangefs_readdir_response_s *readdir)
{
	int i;
	struct orangefs_readdir_response_s *rd =
		(struct orangefs_readdir_response_s *) ptr;
	char *buf = ptr;

	if (size < offsetof(struct orangefs_readdir_response_s, dirent_array))
		return -EINVAL;

	readdir->token = rd->token;
	readdir->orangefs_dirent_outcount = rd->orangefs_dirent_outcount;
	readdir->dirent_array = kcalloc(readdir->orangefs_dirent_outcount,
					sizeof(*readdir->dirent_array),
					GFP_KERNEL);
	if (readdir->dirent_array == NULL)
		return -ENOMEM;

	buf += offsetof(struct orangefs_readdir_response_s, dirent_array);
	size -= offsetof(struct orangefs_readdir_response_s, dirent_array);

	for (i = 0; i < readdir->orangefs_dirent_outcount; i++) {
		__u32 len;

		if (size < 4)
			goto Einval;

		len = *(__u32 *)buf;
		if (len >= (unsigned)-24)
			goto Einval;

		readdir->dirent_array[i].d_name = buf + 4;
		readdir->dirent_array[i].d_length = len;

		len = roundup8(4 + len + 1);
		if (size < len + 16)
			goto Einval;
		size -= len + 16;

		buf += len;

		readdir->dirent_array[i].khandle =
			*(struct orangefs_khandle *) buf;
		buf += 16;
	}
	return buf - ptr;
Einval:
	kfree(readdir->dirent_array);
	readdir->dirent_array = NULL;
	return -EINVAL;
}

static long readdir_handle_ctor(struct readdir_handle_s *rhandle, void *buf,
				size_t size, int buffer_index)
{
	long ret;

	if (buf == NULL) {
		gossip_err
		    ("Invalid NULL buffer specified in readdir_handle_ctor\n");
		return -ENOMEM;
	}
	if (buffer_index < 0) {
		gossip_err
		    ("Invalid buffer index specified in readdir_handle_ctor\n");
		return -EINVAL;
	}
	rhandle->buffer_index = buffer_index;
	rhandle->dents_buf = buf;
	ret = decode_dirents(buf, size, &rhandle->readdir_response);
	if (ret < 0) {
		gossip_err("Could not decode readdir from buffer %ld\n", ret);
		rhandle->buffer_index = -1;
		gossip_debug(GOSSIP_DIR_DEBUG, "vfree %p\n", buf);
		vfree(buf);
		rhandle->dents_buf = NULL;
	}
	return ret;
}

static void readdir_handle_dtor(struct orangefs_bufmap *bufmap,
		struct readdir_handle_s *rhandle)
{
	if (rhandle == NULL)
		return;

	/* kfree(NULL) is safe */
	kfree(rhandle->readdir_response.dirent_array);
	rhandle->readdir_response.dirent_array = NULL;

	if (rhandle->buffer_index >= 0) {
		readdir_index_put(bufmap, rhandle->buffer_index);
		rhandle->buffer_index = -1;
	}
	if (rhandle->dents_buf) {
		gossip_debug(GOSSIP_DIR_DEBUG, "vfree %p\n",
			     rhandle->dents_buf);
		vfree(rhandle->dents_buf);
		rhandle->dents_buf = NULL;
	}
}

/*
 * Read directory entries from an instance of an open directory.
 */
static int orangefs_readdir(struct file *file, struct dir_context *ctx)
{
	struct orangefs_bufmap *bufmap = NULL;
	int ret = 0;
	int buffer_index;
	/*
	 * ptoken supports Orangefs' distributed directory logic, added
	 * in 2.9.2.
	 */
	__u64 *ptoken = file->private_data;
	__u64 pos = 0;
	ino_t ino = 0;
	struct dentry *dentry = file->f_path.dentry;
	struct orangefs_kernel_op_s *new_op = NULL;
	struct orangefs_inode_s *orangefs_inode = ORANGEFS_I(dentry->d_inode);
	int buffer_full = 0;
	struct readdir_handle_s rhandle;
	int i = 0;
	int len = 0;
	ino_t current_ino = 0;
	char *current_entry = NULL;
	long bytes_decoded;

	gossip_debug(GOSSIP_DIR_DEBUG,
		     "%s: ctx->pos:%lld, ptoken = %llu\n",
		     __func__,
		     lld(ctx->pos),
		     llu(*ptoken));

	pos = (__u64) ctx->pos;

	/* are we done? */
	if (pos == ORANGEFS_READDIR_END) {
		gossip_debug(GOSSIP_DIR_DEBUG,
			     "Skipping to termination path\n");
		return 0;
	}

	gossip_debug(GOSSIP_DIR_DEBUG,
		     "orangefs_readdir called on %s (pos=%llu)\n",
		     dentry->d_name.name, llu(pos));

	rhandle.buffer_index = -1;
	rhandle.dents_buf = NULL;
	memset(&rhandle.readdir_response, 0, sizeof(rhandle.readdir_response));

	new_op = op_alloc(ORANGEFS_VFS_OP_READDIR);
	if (!new_op)
		return -ENOMEM;

	new_op->uses_shared_memory = 1;
	new_op->upcall.req.readdir.refn = orangefs_inode->refn;
	new_op->upcall.req.readdir.max_dirent_count = MAX_DIRENT_COUNT_READDIR;

	gossip_debug(GOSSIP_DIR_DEBUG,
		     "%s: upcall.req.readdir.refn.khandle: %pU\n",
		     __func__,
		     &new_op->upcall.req.readdir.refn.khandle);

	new_op->upcall.req.readdir.token = *ptoken;

get_new_buffer_index:
	ret = readdir_index_get(&bufmap, &buffer_index);
	if (ret < 0) {
		gossip_lerr("orangefs_readdir: readdir_index_get() failure (%d)\n",
			    ret);
		goto out_free_op;
	}
	new_op->upcall.req.readdir.buf_index = buffer_index;

	ret = service_operation(new_op,
				"orangefs_readdir",
				get_interruptible_flag(dentry->d_inode));

	gossip_debug(GOSSIP_DIR_DEBUG,
		     "Readdir downcall status is %d.  ret:%d\n",
		     new_op->downcall.status,
		     ret);

	if (ret == -EAGAIN && op_state_purged(new_op)) {
		/*
		 * readdir shared memory aread has been wiped due to
		 * pvfs2-client-core restarting, so we must get a new
		 * index into the shared memory.
		 */
		gossip_debug(GOSSIP_DIR_DEBUG,
			"%s: Getting new buffer_index for retry of readdir..\n",
			 __func__);
		readdir_index_put(bufmap, buffer_index);
		goto get_new_buffer_index;
	}

	if (ret == -EIO && op_state_purged(new_op)) {
		gossip_err("%s: Client is down. Aborting readdir call.\n",
			__func__);
		readdir_index_put(bufmap, buffer_index);
		goto out_free_op;
	}

	if (ret < 0 || new_op->downcall.status != 0) {
		gossip_debug(GOSSIP_DIR_DEBUG,
			     "Readdir request failed.  Status:%d\n",
			     new_op->downcall.status);
		readdir_index_put(bufmap, buffer_index);
		if (ret >= 0)
			ret = new_op->downcall.status;
		goto out_free_op;
	}

	bytes_decoded =
		readdir_handle_ctor(&rhandle,
				    new_op->downcall.trailer_buf,
				    new_op->downcall.trailer_size,
				    buffer_index);
	if (bytes_decoded < 0) {
		gossip_err("orangefs_readdir: Could not decode trailer buffer into a readdir response %d\n",
			ret);
		ret = bytes_decoded;
		readdir_index_put(bufmap, buffer_index);
		goto out_free_op;
	}

	if (bytes_decoded != new_op->downcall.trailer_size) {
		gossip_err("orangefs_readdir: # bytes decoded (%ld) "
			   "!= trailer size (%ld)\n",
			   bytes_decoded,
			   (long)new_op->downcall.trailer_size);
		ret = -EINVAL;
		goto out_destroy_handle;
	}

	/*
	 *  orangefs doesn't actually store dot and dot-dot, but
	 *  we need to have them represented.
	 */
	if (pos == 0) {
		ino = get_ino_from_khandle(dentry->d_inode);
		gossip_debug(GOSSIP_DIR_DEBUG,
			     "%s: calling dir_emit of \".\" with pos = %llu\n",
			     __func__,
			     llu(pos));
		ret = dir_emit(ctx, ".", 1, ino, DT_DIR);
		pos += 1;
	}

	if (pos == 1) {
		ino = get_parent_ino_from_dentry(dentry);
		gossip_debug(GOSSIP_DIR_DEBUG,
			     "%s: calling dir_emit of \"..\" with pos = %llu\n",
			     __func__,
			     llu(pos));
		ret = dir_emit(ctx, "..", 2, ino, DT_DIR);
		pos += 1;
	}

	/*
	 * we stored ORANGEFS_ITERATE_NEXT in ctx->pos last time around
	 * to prevent "finding" dot and dot-dot on any iteration
	 * other than the first.
	 */
	if (ctx->pos == ORANGEFS_ITERATE_NEXT)
		ctx->pos = 0;

	for (i = ctx->pos;
	     i < rhandle.readdir_response.orangefs_dirent_outcount;
	     i++) {
		len = rhandle.readdir_response.dirent_array[i].d_length;
		current_entry = rhandle.readdir_response.dirent_array[i].d_name;
		current_ino = orangefs_khandle_to_ino(
			&(rhandle.readdir_response.dirent_array[i].khandle));

		gossip_debug(GOSSIP_DIR_DEBUG,
			     "calling dir_emit for %s with len %d"
			     ", ctx->pos %ld\n",
			     current_entry,
			     len,
			     (unsigned long)ctx->pos);
		/*
		 * type is unknown. We don't return object type
		 * in the dirent_array. This leaves getdents
		 * clueless about type.
		 */
		ret =
		    dir_emit(ctx, current_entry, len, current_ino, DT_UNKNOWN);
		if (!ret)
			break;
		ctx->pos++;
		gossip_debug(GOSSIP_DIR_DEBUG,
			      "%s: ctx->pos:%lld\n",
			      __func__,
			      lld(ctx->pos));

	}

	/*
	 * we ran all the way through the last batch, set up for
	 * getting another batch...
	 */
	if (ret) {
		*ptoken = rhandle.readdir_response.token;
		ctx->pos = ORANGEFS_ITERATE_NEXT;
	}

	/*
	 * Did we hit the end of the directory?
	 */
	if (rhandle.readdir_response.token == ORANGEFS_READDIR_END &&
	    !buffer_full) {
		gossip_debug(GOSSIP_DIR_DEBUG,
		"End of dir detected; setting ctx->pos to ORANGEFS_READDIR_END.\n");
		ctx->pos = ORANGEFS_READDIR_END;
	}

out_destroy_handle:
	readdir_handle_dtor(bufmap, &rhandle);
out_free_op:
	op_release(new_op);
	gossip_debug(GOSSIP_DIR_DEBUG, "orangefs_readdir returning %d\n", ret);
	return ret;
}

static int orangefs_dir_open(struct inode *inode, struct file *file)
{
	__u64 *ptoken;

	file->private_data = kmalloc(sizeof(__u64), GFP_KERNEL);
	if (!file->private_data)
		return -ENOMEM;

	ptoken = file->private_data;
	*ptoken = ORANGEFS_READDIR_START;
	return 0;
}

static int orangefs_dir_release(struct inode *inode, struct file *file)
{
	orangefs_flush_inode(inode);
	kfree(file->private_data);
	return 0;
}

/** ORANGEFS implementation of VFS directory operations */
const struct file_operations orangefs_dir_operations = {
	.read = generic_read_dir,
	.iterate = orangefs_readdir,
	.open = orangefs_dir_open,
	.release = orangefs_dir_release,
};