#include <linux/ceph/ceph_debug.h>

#include <linux/exportfs.h>
#include <linux/slab.h>
#include <asm/unaligned.h>

#include "super.h"
#include "mds_client.h"

/*
 * Basic fh
 */
struct ceph_nfs_fh {
	u64 ino;
} __attribute__ ((packed));

/*
 * Larger fh that includes parent ino.
 */
struct ceph_nfs_confh {
	u64 ino, parent_ino;
} __attribute__ ((packed));

static int ceph_encode_fh(struct inode *inode, u32 *rawfh, int *max_len,
			  struct inode *parent_inode)
{
	int type;
	struct ceph_nfs_fh *fh = (void *)rawfh;
	struct ceph_nfs_confh *cfh = (void *)rawfh;
	int connected_handle_length = sizeof(*cfh)/4;
	int handle_length = sizeof(*fh)/4;

	/* don't re-export snaps */
	if (ceph_snap(inode) != CEPH_NOSNAP)
		return -EINVAL;

	if (parent_inode && (*max_len < connected_handle_length)) {
		*max_len = connected_handle_length;
		return FILEID_INVALID;
	} else if (*max_len < handle_length) {
		*max_len = handle_length;
		return FILEID_INVALID;
	}

	if (parent_inode) {
		dout("encode_fh %llx with parent %llx\n",
		     ceph_ino(inode), ceph_ino(parent_inode));
		cfh->ino = ceph_ino(inode);
		cfh->parent_ino = ceph_ino(parent_inode);
		*max_len = connected_handle_length;
		type = FILEID_INO32_GEN_PARENT;
	} else {
		dout("encode_fh %llx\n", ceph_ino(inode));
		fh->ino = ceph_ino(inode);
		*max_len = handle_length;
		type = FILEID_INO32_GEN;
	}
	return type;
}

static struct dentry *__fh_to_dentry(struct super_block *sb, u64 ino)
{
	struct ceph_mds_client *mdsc = ceph_sb_to_client(sb)->mdsc;
	struct inode *inode;
	struct dentry *dentry;
	struct ceph_vino vino;
	int err;

	vino.ino = ino;
	vino.snap = CEPH_NOSNAP;
	inode = ceph_find_inode(sb, vino);
	if (!inode) {
		struct ceph_mds_request *req;

		req = ceph_mdsc_create_request(mdsc, CEPH_MDS_OP_LOOKUPINO,
					       USE_ANY_MDS);
		if (IS_ERR(req))
			return ERR_CAST(req);

		req->r_ino1 = vino;
		req->r_num_caps = 1;
		err = ceph_mdsc_do_request(mdsc, NULL, req);
		inode = req->r_target_inode;
		if (inode)
			ihold(inode);
		ceph_mdsc_put_request(req);
		if (!inode)
			return ERR_PTR(-ESTALE);
	}

	dentry = d_obtain_alias(inode);
	if (IS_ERR(dentry)) {
		iput(inode);
		return dentry;
	}
	err = ceph_init_dentry(dentry);
	if (err < 0) {
		dput(dentry);
		return ERR_PTR(err);
	}
	dout("__fh_to_dentry %llx %p dentry %p\n", ino, inode, dentry);
	return dentry;
}

/*
 * convert regular fh to dentry
 */
static struct dentry *ceph_fh_to_dentry(struct super_block *sb,
					struct fid *fid,
					int fh_len, int fh_type)
{
	struct ceph_nfs_fh *fh = (void *)fid->raw;

	if (fh_type != FILEID_INO32_GEN  &&
	    fh_type != FILEID_INO32_GEN_PARENT)
		return NULL;
	if (fh_len < sizeof(*fh) / 4)
		return NULL;

	dout("fh_to_dentry %llx\n", fh->ino);
	return __fh_to_dentry(sb, fh->ino);
}

static struct dentry *__get_parent(struct super_block *sb,
				   struct dentry *child, u64 ino)
{
	struct ceph_mds_client *mdsc = ceph_sb_to_client(sb)->mdsc;
	struct ceph_mds_request *req;
	struct inode *inode;
	struct dentry *dentry;
	int err;

	req = ceph_mdsc_create_request(mdsc, CEPH_MDS_OP_LOOKUPPARENT,
				       USE_ANY_MDS);
	if (IS_ERR(req))
		return ERR_CAST(req);

	if (child) {
		req->r_inode = child->d_inode;
		ihold(child->d_inode);
	} else {
		req->r_ino1 = (struct ceph_vino) {
			.ino = ino,
			.snap = CEPH_NOSNAP,
		};
	}
	req->r_num_caps = 1;
	err = ceph_mdsc_do_request(mdsc, NULL, req);
	inode = req->r_target_inode;
	if (inode)
		ihold(inode);
	ceph_mdsc_put_request(req);
	if (!inode)
		return ERR_PTR(-ENOENT);

	dentry = d_obtain_alias(inode);
	if (IS_ERR(dentry)) {
		iput(inode);
		return dentry;
	}
	err = ceph_init_dentry(dentry);
	if (err < 0) {
		dput(dentry);
		return ERR_PTR(err);
	}
	dout("__get_parent ino %llx parent %p ino %llx.%llx\n",
	     child ? ceph_ino(child->d_inode) : ino,
	     dentry, ceph_vinop(inode));
	return dentry;
}

struct dentry *ceph_get_parent(struct dentry *child)
{
	/* don't re-export snaps */
	if (ceph_snap(child->d_inode) != CEPH_NOSNAP)
		return ERR_PTR(-EINVAL);

	dout("get_parent %p ino %llx.%llx\n",
	     child, ceph_vinop(child->d_inode));
	return __get_parent(child->d_sb, child, 0);
}

/*
 * get parent, if possible.
 *
 * FIXME: we could do better by querying the mds to discover the
 * parent.
 */
static struct dentry *ceph_fh_to_parent(struct super_block *sb,
					 struct fid *fid,
					int fh_len, int fh_type)
{
	struct ceph_nfs_confh *cfh = (void *)fid->raw;
	struct ceph_vino vino;
	struct inode *inode;
	struct dentry *dentry;
	int err;

	if (fh_type == 1)
		return ERR_PTR(-ESTALE);
	if (fh_len < sizeof(*cfh) / 4)
		return ERR_PTR(-ESTALE);

	pr_debug("fh_to_parent %llx/%d\n", cfh->parent_ino,
		 cfh->parent_name_hash);

	vino.ino = cfh->ino;
	vino.snap = CEPH_NOSNAP;
	inode = ceph_find_inode(sb, vino);
	if (!inode)
		return ERR_PTR(-ESTALE);

	dentry = d_obtain_alias(inode);
	if (IS_ERR(dentry)) {
		pr_err("fh_to_parent %llx -- inode %p but ENOMEM\n",
		       cfh->ino, inode);
		iput(inode);
		return dentry;
	}
	err = ceph_init_dentry(dentry);
	if (err < 0) {
		iput(inode);
		return ERR_PTR(err);
	}
	dout("fh_to_parent %llx %p dentry %p\n", cfh->ino, inode, dentry);
	return dentry;
}

const struct export_operations ceph_export_ops = {
	.encode_fh = ceph_encode_fh,
	.fh_to_dentry = ceph_fh_to_dentry,
	.fh_to_parent = ceph_fh_to_parent,
	.get_parent = ceph_get_parent,
};