fs/ceph/export.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0
 #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));

 /*
  * fh for snapped inode
  */
 struct ceph_nfs_snapfh {
 	u64 ino;
 	u64 snapid;
 	u64 parent_ino;
 	u32 hash;
 } __attribute__ ((packed));

 static int ceph_encode_snapfh(struct inode *inode, u32 *rawfh, int *max_len,
 			      struct inode *parent_inode)
 {
 	static const int snap_handle_length =
 		sizeof(struct ceph_nfs_snapfh) >> 2;
 	struct ceph_nfs_snapfh *sfh = (void *)rawfh;
 	u64 snapid = ceph_snap(inode);
 	int ret;
 	bool no_parent = true;

 	if (*max_len < snap_handle_length) {
 		*max_len = snap_handle_length;
 		ret = FILEID_INVALID;
 		goto out;
 	}

 	ret =  -EINVAL;
 	if (snapid != CEPH_SNAPDIR) {
 		struct inode *dir;
 		struct dentry *dentry = d_find_alias(inode);
 		if (!dentry)
 			goto out;

 		rcu_read_lock();
 		dir = d_inode_rcu(dentry->d_parent);
 		if (ceph_snap(dir) != CEPH_SNAPDIR) {
 			sfh->parent_ino = ceph_ino(dir);
 			sfh->hash = ceph_dentry_hash(dir, dentry);
 			no_parent = false;
 		}
 		rcu_read_unlock();
 		dput(dentry);
 	}

 	if (no_parent) {
 		if (!S_ISDIR(inode->i_mode))
 			goto out;
 		sfh->parent_ino = sfh->ino;
 		sfh->hash = 0;
 	}
 	sfh->ino = ceph_ino(inode);
 	sfh->snapid = snapid;

 	*max_len = snap_handle_length;
 	ret = FILEID_BTRFS_WITH_PARENT;
 out:
 	dout("encode_snapfh %llx.%llx ret=%d\n", ceph_vinop(inode), ret);
 	return ret;
 }

 static int ceph_encode_fh(struct inode *inode, u32 *rawfh, int *max_len,
 			  struct inode *parent_inode)
 {
 	static const int handle_length =
 		sizeof(struct ceph_nfs_fh) >> 2;
 	static const int connected_handle_length =
 		sizeof(struct ceph_nfs_confh) >> 2;
 	int type;

 	if (ceph_snap(inode) != CEPH_NOSNAP)
 		return ceph_encode_snapfh(inode, rawfh, max_len, parent_inode);

 	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) {
 		struct ceph_nfs_confh *cfh = (void *)rawfh;
 		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 {
 		struct ceph_nfs_fh *fh = (void *)rawfh;
 		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 inode *__lookup_inode(struct super_block *sb, u64 ino)
 {
 	struct ceph_mds_client *mdsc = ceph_sb_to_client(sb)->mdsc;
 	struct inode *inode;
 	struct ceph_vino vino;
 	int err;

 	vino.ino = ino;
 	vino.snap = CEPH_NOSNAP;

 	if (ceph_vino_is_reserved(vino))
 		return ERR_PTR(-ESTALE);

 	inode = ceph_find_inode(sb, vino);
 	if (!inode) {
 		struct ceph_mds_request *req;
 		int mask;

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

 		mask = CEPH_STAT_CAP_INODE;
 		if (ceph_security_xattr_wanted(d_inode(sb->s_root)))
 			mask |= CEPH_CAP_XATTR_SHARED;
 		req->r_args.lookupino.mask = cpu_to_le32(mask);

 		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 < 0 ? ERR_PTR(err) : ERR_PTR(-ESTALE);
 	}
 	return inode;
 }

 struct inode *ceph_lookup_inode(struct super_block *sb, u64 ino)
 {
 	struct inode *inode = __lookup_inode(sb, ino);
 	if (IS_ERR(inode))
 		return inode;
 	if (inode->i_nlink == 0) {
 		iput(inode);
 		return ERR_PTR(-ESTALE);
 	}
 	return inode;
 }

 static struct dentry *__fh_to_dentry(struct super_block *sb, u64 ino)
 {
 	struct inode *inode = __lookup_inode(sb, ino);
 	int err;

 	if (IS_ERR(inode))
 		return ERR_CAST(inode);
 	/* We need LINK caps to reliably check i_nlink */
 	err = ceph_do_getattr(inode, CEPH_CAP_LINK_SHARED, false);
 	if (err) {
 		iput(inode);
 		return ERR_PTR(err);
 	}
 	/* -ESTALE if inode as been unlinked and no file is open */
 	if ((inode->i_nlink == 0) && (atomic_read(&inode->i_count) == 1)) {
 		iput(inode);
 		return ERR_PTR(-ESTALE);
 	}
 	return d_obtain_alias(inode);
 }

 static struct dentry *__snapfh_to_dentry(struct super_block *sb,
 					  struct ceph_nfs_snapfh *sfh,
 					  bool want_parent)
 {
 	struct ceph_mds_client *mdsc = ceph_sb_to_client(sb)->mdsc;
 	struct ceph_mds_request *req;
 	struct inode *inode;
 	struct ceph_vino vino;
 	int mask;
 	int err;
 	bool unlinked = false;

 	if (want_parent) {
 		vino.ino = sfh->parent_ino;
 		if (sfh->snapid == CEPH_SNAPDIR)
 			vino.snap = CEPH_NOSNAP;
 		else if (sfh->ino == sfh->parent_ino)
 			vino.snap = CEPH_SNAPDIR;
 		else
 			vino.snap = sfh->snapid;
 	} else {
 		vino.ino = sfh->ino;
 		vino.snap = sfh->snapid;
 	}

 	if (ceph_vino_is_reserved(vino))
 		return ERR_PTR(-ESTALE);

 	inode = ceph_find_inode(sb, vino);
 	if (inode)
 		return d_obtain_alias(inode);

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

 	mask = CEPH_STAT_CAP_INODE;
 	if (ceph_security_xattr_wanted(d_inode(sb->s_root)))
 		mask |= CEPH_CAP_XATTR_SHARED;
 	req->r_args.lookupino.mask = cpu_to_le32(mask);
 	if (vino.snap < CEPH_NOSNAP) {
 		req->r_args.lookupino.snapid = cpu_to_le64(vino.snap);
 		if (!want_parent && sfh->ino != sfh->parent_ino) {
 			req->r_args.lookupino.parent =
 					cpu_to_le64(sfh->parent_ino);
 			req->r_args.lookupino.hash =
 					cpu_to_le32(sfh->hash);
 		}
 	}

 	req->r_ino1 = vino;
 	req->r_num_caps = 1;
 	err = ceph_mdsc_do_request(mdsc, NULL, req);
 	inode = req->r_target_inode;
 	if (inode) {
 		if (vino.snap == CEPH_SNAPDIR) {
 			if (inode->i_nlink == 0)
 				unlinked = true;
 			inode = ceph_get_snapdir(inode);
 		} else if (ceph_snap(inode) == vino.snap) {
 			ihold(inode);
 		} else {
 			/* mds does not support lookup snapped inode */
 			err = -EOPNOTSUPP;
 			inode = NULL;
 		}
 	}
 	ceph_mdsc_put_request(req);

 	if (want_parent) {
 		dout("snapfh_to_parent %llx.%llx\n err=%d\n",
 		     vino.ino, vino.snap, err);
 	} else {
 		dout("snapfh_to_dentry %llx.%llx parent %llx hash %x err=%d",
 		      vino.ino, vino.snap, sfh->parent_ino, sfh->hash, err);
 	}
 	if (!inode)
 		return ERR_PTR(-ESTALE);
 	/* see comments in ceph_get_parent() */
 	return unlinked ? d_obtain_root(inode) : d_obtain_alias(inode);
 }

 /*
  * 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_BTRFS_WITH_PARENT) {
 		struct ceph_nfs_snapfh *sfh = (void *)fid->raw;
 		return __snapfh_to_dentry(sb, sfh, false);
 	}

 	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;
 	int mask;
 	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 = d_inode(child);
 		ihold(d_inode(child));
 	} else {
 		req->r_ino1 = (struct ceph_vino) {
 			.ino = ino,
 			.snap = CEPH_NOSNAP,
 		};
 	}

 	mask = CEPH_STAT_CAP_INODE;
 	if (ceph_security_xattr_wanted(d_inode(sb->s_root)))
 		mask |= CEPH_CAP_XATTR_SHARED;
 	req->r_args.getattr.mask = cpu_to_le32(mask);

 	req->r_num_caps = 1;
 	err = ceph_mdsc_do_request(mdsc, NULL, req);
 	if (err) {
 		ceph_mdsc_put_request(req);
 		return ERR_PTR(err);
 	}

 	inode = req->r_target_inode;
 	if (inode)
 		ihold(inode);
 	ceph_mdsc_put_request(req);
 	if (!inode)
 		return ERR_PTR(-ENOENT);

 	return d_obtain_alias(inode);
 }

 static struct dentry *ceph_get_parent(struct dentry *child)
 {
 	struct inode *inode = d_inode(child);
 	struct dentry *dn;

 	if (ceph_snap(inode) != CEPH_NOSNAP) {
 		struct inode* dir;
 		bool unlinked = false;
 		/* do not support non-directory */
 		if (!d_is_dir(child)) {
 			dn = ERR_PTR(-EINVAL);
 			goto out;
 		}
 		dir = __lookup_inode(inode->i_sb, ceph_ino(inode));
 		if (IS_ERR(dir)) {
 			dn = ERR_CAST(dir);
 			goto out;
 		}
 		/* There can be multiple paths to access snapped inode.
 		 * For simplicity, treat snapdir of head inode as parent */
 		if (ceph_snap(inode) != CEPH_SNAPDIR) {
 			struct inode *snapdir = ceph_get_snapdir(dir);
 			if (dir->i_nlink == 0)
 				unlinked = true;
 			iput(dir);
 			if (IS_ERR(snapdir)) {
 				dn = ERR_CAST(snapdir);
 				goto out;
 			}
 			dir = snapdir;
 		}
 		/* If directory has already been deleted, futher get_parent
 		 * will fail. Do not mark snapdir dentry as disconnected,
 		 * this prevent exportfs from doing futher get_parent. */
 		if (unlinked)
 			dn = d_obtain_root(dir);
 		else
 			dn = d_obtain_alias(dir);
 	} else {
 		dn = __get_parent(child->d_sb, child, 0);
 	}
 out:
 	dout("get_parent %p ino %llx.%llx err=%ld\n",
 	     child, ceph_vinop(inode), (long)PTR_ERR_OR_ZERO(dn));
 	return dn;
 }

 /*
  * convert regular fh to 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 dentry *dentry;

 	if (fh_type == FILEID_BTRFS_WITH_PARENT) {
 		struct ceph_nfs_snapfh *sfh = (void *)fid->raw;
 		return __snapfh_to_dentry(sb, sfh, true);
 	}

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

 	dout("fh_to_parent %llx\n", cfh->parent_ino);
 	dentry = __get_parent(sb, NULL, cfh->ino);
 	if (unlikely(dentry == ERR_PTR(-ENOENT)))
 		dentry = __fh_to_dentry(sb, cfh->parent_ino);
 	return dentry;
 }

 static int __get_snap_name(struct dentry *parent, char *name,
 			   struct dentry *child)
 {
 	struct inode *inode = d_inode(child);
 	struct inode *dir = d_inode(parent);
 	struct ceph_fs_client *fsc = ceph_inode_to_client(inode);
 	struct ceph_mds_request *req = NULL;
 	char *last_name = NULL;
 	unsigned next_offset = 2;
 	int err = -EINVAL;

 	if (ceph_ino(inode) != ceph_ino(dir))
 		goto out;
 	if (ceph_snap(inode) == CEPH_SNAPDIR) {
 		if (ceph_snap(dir) == CEPH_NOSNAP) {
 			strcpy(name, fsc->mount_options->snapdir_name);
 			err = 0;
 		}
 		goto out;
 	}
 	if (ceph_snap(dir) != CEPH_SNAPDIR)
 		goto out;

 	while (1) {
 		struct ceph_mds_reply_info_parsed *rinfo;
 		struct ceph_mds_reply_dir_entry *rde;
 		int i;

 		req = ceph_mdsc_create_request(fsc->mdsc, CEPH_MDS_OP_LSSNAP,
 					       USE_AUTH_MDS);
 		if (IS_ERR(req)) {
 			err = PTR_ERR(req);
 			req = NULL;
 			goto out;
 		}
 		err = ceph_alloc_readdir_reply_buffer(req, inode);
 		if (err)
 			goto out;

 		req->r_direct_mode = USE_AUTH_MDS;
 		req->r_readdir_offset = next_offset;
 		req->r_args.readdir.flags =
 				cpu_to_le16(CEPH_READDIR_REPLY_BITFLAGS);
 		if (last_name) {
 			req->r_path2 = last_name;
 			last_name = NULL;
 		}

 		req->r_inode = dir;
 		ihold(dir);
 		req->r_dentry = dget(parent);

 		inode_lock(dir);
 		err = ceph_mdsc_do_request(fsc->mdsc, NULL, req);
 		inode_unlock(dir);

 		if (err < 0)
 			goto out;

 		rinfo = &req->r_reply_info;
 		for (i = 0; i < rinfo->dir_nr; i++) {
 			rde = rinfo->dir_entries + i;
 			BUG_ON(!rde->inode.in);
 			if (ceph_snap(inode) ==
 			    le64_to_cpu(rde->inode.in->snapid)) {
 				memcpy(name, rde->name, rde->name_len);
 				name[rde->name_len] = '\0';
 				err = 0;
 				goto out;
 			}
 		}

 		if (rinfo->dir_end)
 			break;

 		BUG_ON(rinfo->dir_nr <= 0);
 		rde = rinfo->dir_entries + (rinfo->dir_nr - 1);
 		next_offset += rinfo->dir_nr;
 		last_name = kstrndup(rde->name, rde->name_len, GFP_KERNEL);
 		if (!last_name) {
 			err = -ENOMEM;
 			goto out;
 		}

 		ceph_mdsc_put_request(req);
 		req = NULL;
 	}
 	err = -ENOENT;
 out:
 	if (req)
 		ceph_mdsc_put_request(req);
 	kfree(last_name);
 	dout("get_snap_name %p ino %llx.%llx err=%d\n",
 	     child, ceph_vinop(inode), err);
 	return err;
 }

 static int ceph_get_name(struct dentry *parent, char *name,
 			 struct dentry *child)
 {
 	struct ceph_mds_client *mdsc;
 	struct ceph_mds_request *req;
 	struct inode *inode = d_inode(child);
 	int err;

 	if (ceph_snap(inode) != CEPH_NOSNAP)
 		return __get_snap_name(parent, name, child);

 	mdsc = ceph_inode_to_client(inode)->mdsc;
 	req = ceph_mdsc_create_request(mdsc, CEPH_MDS_OP_LOOKUPNAME,
 				       USE_ANY_MDS);
 	if (IS_ERR(req))
 		return PTR_ERR(req);

 	inode_lock(d_inode(parent));

 	req->r_inode = inode;
 	ihold(inode);
 	req->r_ino2 = ceph_vino(d_inode(parent));
 	req->r_parent = d_inode(parent);
 	set_bit(CEPH_MDS_R_PARENT_LOCKED, &req->r_req_flags);
 	req->r_num_caps = 2;
 	err = ceph_mdsc_do_request(mdsc, NULL, req);

 	inode_unlock(d_inode(parent));

 	if (!err) {
 		struct ceph_mds_reply_info_parsed *rinfo = &req->r_reply_info;
 		memcpy(name, rinfo->dname, rinfo->dname_len);
 		name[rinfo->dname_len] = 0;
 		dout("get_name %p ino %llx.%llx name %s\n",
 		     child, ceph_vinop(inode), name);
 	} else {
 		dout("get_name %p ino %llx.%llx err %d\n",
 		     child, ceph_vinop(inode), err);
 	}

 	ceph_mdsc_put_request(req);
 	return err;
 }

 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,
 	.get_name = ceph_get_name,
 };
	// SPDX-License-Identifier: GPL-2.0
	#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));

	/*
	* fh for snapped inode
	*/
	struct ceph_nfs_snapfh {
	u64 ino;
	u64 snapid;
	u64 parent_ino;
	u32 hash;
	} __attribute__ ((packed));

	static int ceph_encode_snapfh(struct inode inode, u32 rawfh, int *max_len,
	struct inode *parent_inode)
	{
	static const int snap_handle_length =
	sizeof(struct ceph_nfs_snapfh) >> 2;
	struct ceph_nfs_snapfh sfh = (void )rawfh;
	u64 snapid = ceph_snap(inode);
	int ret;
	bool no_parent = true;

	if (*max_len < snap_handle_length) {
	*max_len = snap_handle_length;
	ret = FILEID_INVALID;
	goto out;
	}

	ret = -EINVAL;
	if (snapid != CEPH_SNAPDIR) {
	struct inode *dir;
	struct dentry *dentry = d_find_alias(inode);
	if (!dentry)
	goto out;

	rcu_read_lock();
	dir = d_inode_rcu(dentry->d_parent);
	if (ceph_snap(dir) != CEPH_SNAPDIR) {
	sfh->parent_ino = ceph_ino(dir);
	sfh->hash = ceph_dentry_hash(dir, dentry);
	no_parent = false;
	}
	rcu_read_unlock();
	dput(dentry);
	}

	if (no_parent) {
	if (!S_ISDIR(inode->i_mode))
	goto out;
	sfh->parent_ino = sfh->ino;
	sfh->hash = 0;
	}
	sfh->ino = ceph_ino(inode);
	sfh->snapid = snapid;

	*max_len = snap_handle_length;
	ret = FILEID_BTRFS_WITH_PARENT;
	out:
	dout("encode_snapfh %llx.%llx ret=%d\n", ceph_vinop(inode), ret);
	return ret;
	}

	static int ceph_encode_fh(struct inode inode, u32 rawfh, int *max_len,
	struct inode *parent_inode)
	{
	static const int handle_length =
	sizeof(struct ceph_nfs_fh) >> 2;
	static const int connected_handle_length =
	sizeof(struct ceph_nfs_confh) >> 2;
	int type;

	if (ceph_snap(inode) != CEPH_NOSNAP)
	return ceph_encode_snapfh(inode, rawfh, max_len, parent_inode);

	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) {
	struct ceph_nfs_confh cfh = (void )rawfh;
	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 {
	struct ceph_nfs_fh fh = (void )rawfh;
	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 inode __lookup_inode(struct super_block sb, u64 ino)
	{
	struct ceph_mds_client *mdsc = ceph_sb_to_client(sb)->mdsc;
	struct inode *inode;
	struct ceph_vino vino;
	int err;

	vino.ino = ino;
	vino.snap = CEPH_NOSNAP;

	if (ceph_vino_is_reserved(vino))
	return ERR_PTR(-ESTALE);

	inode = ceph_find_inode(sb, vino);
	if (!inode) {
	struct ceph_mds_request *req;
	int mask;

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

	mask = CEPH_STAT_CAP_INODE;
	if (ceph_security_xattr_wanted(d_inode(sb->s_root)))
	mask \|= CEPH_CAP_XATTR_SHARED;
	req->r_args.lookupino.mask = cpu_to_le32(mask);

	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 < 0 ? ERR_PTR(err) : ERR_PTR(-ESTALE);
	}
	return inode;
	}

	struct inode ceph_lookup_inode(struct super_block sb, u64 ino)
	{
	struct inode *inode = __lookup_inode(sb, ino);
	if (IS_ERR(inode))
	return inode;
	if (inode->i_nlink == 0) {
	iput(inode);
	return ERR_PTR(-ESTALE);
	}
	return inode;
	}

	static struct dentry __fh_to_dentry(struct super_block sb, u64 ino)
	{
	struct inode *inode = __lookup_inode(sb, ino);
	int err;

	if (IS_ERR(inode))
	return ERR_CAST(inode);
	/* We need LINK caps to reliably check i_nlink */
	err = ceph_do_getattr(inode, CEPH_CAP_LINK_SHARED, false);
	if (err) {
	iput(inode);
	return ERR_PTR(err);
	}
	/* -ESTALE if inode as been unlinked and no file is open */
	if ((inode->i_nlink == 0) && (atomic_read(&inode->i_count) == 1)) {
	iput(inode);
	return ERR_PTR(-ESTALE);
	}
	return d_obtain_alias(inode);
	}

	static struct dentry __snapfh_to_dentry(struct super_block sb,
	struct ceph_nfs_snapfh *sfh,
	bool want_parent)
	{
	struct ceph_mds_client *mdsc = ceph_sb_to_client(sb)->mdsc;
	struct ceph_mds_request *req;
	struct inode *inode;
	struct ceph_vino vino;
	int mask;
	int err;
	bool unlinked = false;

	if (want_parent) {
	vino.ino = sfh->parent_ino;
	if (sfh->snapid == CEPH_SNAPDIR)
	vino.snap = CEPH_NOSNAP;
	else if (sfh->ino == sfh->parent_ino)
	vino.snap = CEPH_SNAPDIR;
	else
	vino.snap = sfh->snapid;
	} else {
	vino.ino = sfh->ino;
	vino.snap = sfh->snapid;
	}

	if (ceph_vino_is_reserved(vino))
	return ERR_PTR(-ESTALE);

	inode = ceph_find_inode(sb, vino);
	if (inode)
	return d_obtain_alias(inode);

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

	mask = CEPH_STAT_CAP_INODE;
	if (ceph_security_xattr_wanted(d_inode(sb->s_root)))
	mask \|= CEPH_CAP_XATTR_SHARED;
	req->r_args.lookupino.mask = cpu_to_le32(mask);
	if (vino.snap < CEPH_NOSNAP) {
	req->r_args.lookupino.snapid = cpu_to_le64(vino.snap);
	if (!want_parent && sfh->ino != sfh->parent_ino) {
	req->r_args.lookupino.parent =
	cpu_to_le64(sfh->parent_ino);
	req->r_args.lookupino.hash =
	cpu_to_le32(sfh->hash);
	}
	}

	req->r_ino1 = vino;
	req->r_num_caps = 1;
	err = ceph_mdsc_do_request(mdsc, NULL, req);
	inode = req->r_target_inode;
	if (inode) {
	if (vino.snap == CEPH_SNAPDIR) {
	if (inode->i_nlink == 0)
	unlinked = true;
	inode = ceph_get_snapdir(inode);
	} else if (ceph_snap(inode) == vino.snap) {
	ihold(inode);
	} else {
	/* mds does not support lookup snapped inode */
	err = -EOPNOTSUPP;
	inode = NULL;
	}
	}
	ceph_mdsc_put_request(req);

	if (want_parent) {
	dout("snapfh_to_parent %llx.%llx\n err=%d\n",
	vino.ino, vino.snap, err);
	} else {
	dout("snapfh_to_dentry %llx.%llx parent %llx hash %x err=%d",
	vino.ino, vino.snap, sfh->parent_ino, sfh->hash, err);
	}
	if (!inode)
	return ERR_PTR(-ESTALE);
	/* see comments in ceph_get_parent() */
	return unlinked ? d_obtain_root(inode) : d_obtain_alias(inode);
	}

	/*
	* 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_BTRFS_WITH_PARENT) {
	struct ceph_nfs_snapfh sfh = (void )fid->raw;
	return __snapfh_to_dentry(sb, sfh, false);
	}

	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;
	int mask;
	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 = d_inode(child);
	ihold(d_inode(child));
	} else {
	req->r_ino1 = (struct ceph_vino) {
	.ino = ino,
	.snap = CEPH_NOSNAP,
	};
	}

	mask = CEPH_STAT_CAP_INODE;
	if (ceph_security_xattr_wanted(d_inode(sb->s_root)))
	mask \|= CEPH_CAP_XATTR_SHARED;
	req->r_args.getattr.mask = cpu_to_le32(mask);

	req->r_num_caps = 1;
	err = ceph_mdsc_do_request(mdsc, NULL, req);
	if (err) {
	ceph_mdsc_put_request(req);
	return ERR_PTR(err);
	}

	inode = req->r_target_inode;
	if (inode)
	ihold(inode);
	ceph_mdsc_put_request(req);
	if (!inode)
	return ERR_PTR(-ENOENT);

	return d_obtain_alias(inode);
	}

	static struct dentry ceph_get_parent(struct dentry child)
	{
	struct inode *inode = d_inode(child);
	struct dentry *dn;

	if (ceph_snap(inode) != CEPH_NOSNAP) {
	struct inode* dir;
	bool unlinked = false;
	/* do not support non-directory */
	if (!d_is_dir(child)) {
	dn = ERR_PTR(-EINVAL);
	goto out;
	}
	dir = __lookup_inode(inode->i_sb, ceph_ino(inode));
	if (IS_ERR(dir)) {
	dn = ERR_CAST(dir);
	goto out;
	}
	/* There can be multiple paths to access snapped inode.
	* For simplicity, treat snapdir of head inode as parent */
	if (ceph_snap(inode) != CEPH_SNAPDIR) {
	struct inode *snapdir = ceph_get_snapdir(dir);
	if (dir->i_nlink == 0)
	unlinked = true;
	iput(dir);
	if (IS_ERR(snapdir)) {
	dn = ERR_CAST(snapdir);
	goto out;
	}
	dir = snapdir;
	}
	/* If directory has already been deleted, futher get_parent
	* will fail. Do not mark snapdir dentry as disconnected,
	* this prevent exportfs from doing futher get_parent. */
	if (unlinked)
	dn = d_obtain_root(dir);
	else
	dn = d_obtain_alias(dir);
	} else {
	dn = __get_parent(child->d_sb, child, 0);
	}
	out:
	dout("get_parent %p ino %llx.%llx err=%ld\n",
	child, ceph_vinop(inode), (long)PTR_ERR_OR_ZERO(dn));
	return dn;
	}

	/*
	* convert regular fh to 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 dentry *dentry;

	if (fh_type == FILEID_BTRFS_WITH_PARENT) {
	struct ceph_nfs_snapfh sfh = (void )fid->raw;
	return __snapfh_to_dentry(sb, sfh, true);
	}

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

	dout("fh_to_parent %llx\n", cfh->parent_ino);
	dentry = __get_parent(sb, NULL, cfh->ino);
	if (unlikely(dentry == ERR_PTR(-ENOENT)))
	dentry = __fh_to_dentry(sb, cfh->parent_ino);
	return dentry;
	}

	static int __get_snap_name(struct dentry parent, char name,
	struct dentry *child)
	{
	struct inode *inode = d_inode(child);
	struct inode *dir = d_inode(parent);
	struct ceph_fs_client *fsc = ceph_inode_to_client(inode);
	struct ceph_mds_request *req = NULL;
	char *last_name = NULL;
	unsigned next_offset = 2;
	int err = -EINVAL;

	if (ceph_ino(inode) != ceph_ino(dir))
	goto out;
	if (ceph_snap(inode) == CEPH_SNAPDIR) {
	if (ceph_snap(dir) == CEPH_NOSNAP) {
	strcpy(name, fsc->mount_options->snapdir_name);
	err = 0;
	}
	goto out;
	}
	if (ceph_snap(dir) != CEPH_SNAPDIR)
	goto out;

	while (1) {
	struct ceph_mds_reply_info_parsed *rinfo;
	struct ceph_mds_reply_dir_entry *rde;
	int i;

	req = ceph_mdsc_create_request(fsc->mdsc, CEPH_MDS_OP_LSSNAP,
	USE_AUTH_MDS);
	if (IS_ERR(req)) {
	err = PTR_ERR(req);
	req = NULL;
	goto out;
	}
	err = ceph_alloc_readdir_reply_buffer(req, inode);
	if (err)
	goto out;

	req->r_direct_mode = USE_AUTH_MDS;
	req->r_readdir_offset = next_offset;
	req->r_args.readdir.flags =
	cpu_to_le16(CEPH_READDIR_REPLY_BITFLAGS);
	if (last_name) {
	req->r_path2 = last_name;
	last_name = NULL;
	}

	req->r_inode = dir;
	ihold(dir);
	req->r_dentry = dget(parent);

	inode_lock(dir);
	err = ceph_mdsc_do_request(fsc->mdsc, NULL, req);
	inode_unlock(dir);

	if (err < 0)
	goto out;

	rinfo = &req->r_reply_info;
	for (i = 0; i < rinfo->dir_nr; i++) {
	rde = rinfo->dir_entries + i;
	BUG_ON(!rde->inode.in);
	if (ceph_snap(inode) ==
	le64_to_cpu(rde->inode.in->snapid)) {
	memcpy(name, rde->name, rde->name_len);
	name[rde->name_len] = '\0';
	err = 0;
	goto out;
	}
	}

	if (rinfo->dir_end)
	break;

	BUG_ON(rinfo->dir_nr <= 0);
	rde = rinfo->dir_entries + (rinfo->dir_nr - 1);
	next_offset += rinfo->dir_nr;
	last_name = kstrndup(rde->name, rde->name_len, GFP_KERNEL);
	if (!last_name) {
	err = -ENOMEM;
	goto out;
	}

	ceph_mdsc_put_request(req);
	req = NULL;
	}
	err = -ENOENT;
	out:
	if (req)
	ceph_mdsc_put_request(req);
	kfree(last_name);
	dout("get_snap_name %p ino %llx.%llx err=%d\n",
	child, ceph_vinop(inode), err);
	return err;
	}

	static int ceph_get_name(struct dentry parent, char name,
	struct dentry *child)
	{
	struct ceph_mds_client *mdsc;
	struct ceph_mds_request *req;
	struct inode *inode = d_inode(child);
	int err;

	if (ceph_snap(inode) != CEPH_NOSNAP)
	return __get_snap_name(parent, name, child);

	mdsc = ceph_inode_to_client(inode)->mdsc;
	req = ceph_mdsc_create_request(mdsc, CEPH_MDS_OP_LOOKUPNAME,
	USE_ANY_MDS);
	if (IS_ERR(req))
	return PTR_ERR(req);

	inode_lock(d_inode(parent));

	req->r_inode = inode;
	ihold(inode);
	req->r_ino2 = ceph_vino(d_inode(parent));
	req->r_parent = d_inode(parent);
	set_bit(CEPH_MDS_R_PARENT_LOCKED, &req->r_req_flags);
	req->r_num_caps = 2;
	err = ceph_mdsc_do_request(mdsc, NULL, req);

	inode_unlock(d_inode(parent));

	if (!err) {
	struct ceph_mds_reply_info_parsed *rinfo = &req->r_reply_info;
	memcpy(name, rinfo->dname, rinfo->dname_len);
	name[rinfo->dname_len] = 0;
	dout("get_name %p ino %llx.%llx name %s\n",
	child, ceph_vinop(inode), name);
	} else {
	dout("get_name %p ino %llx.%llx err %d\n",
	child, ceph_vinop(inode), err);
	}

	ceph_mdsc_put_request(req);
	return err;
	}

	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,
	.get_name = ceph_get_name,
	};