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Commit a8e63b7d authored by Sage Weil's avatar Sage Weil
Browse files

ceph: nfs re-export support 



Basic NFS re-export support is included.  This mostly works.  However,
Ceph's MDS design precludes the ability to generate a (small)
filehandle that will be valid forever, so this is of limited utility.

Signed-off-by: default avatarSage Weil <sage@newdream.net>
parent 8fc91fd8

fs/ceph/export.c

0 → 100644
+223 −0
Original line number Diff line number Diff line 
#include "ceph_debug.h"



#include <linux/exportfs.h>

#include <asm/unaligned.h>



#include "super.h"



/*

 * NFS export support

 *

 * NFS re-export of a ceph mount is, at present, only semireliable.

 * The basic issue is that the Ceph architectures doesn't lend itself

 * well to generating filehandles that will remain valid forever.

 *

 * So, we do our best.  If you're lucky, your inode will be in the

 * client's cache.  If it's not, and you have a connectable fh, then

 * the MDS server may be able to find it for you.  Otherwise, you get

 * ESTALE.

 *

 * There are ways to this more reliable, but in the non-connectable fh

 * case, we won't every work perfectly, and in the connectable case,

 * some changes are needed on the MDS side to work better.

 */



/*

 * Basic fh

 */

struct ceph_nfs_fh {

	u64 ino;

} __attribute__ ((packed));



/*

 * Larger 'connectable' fh that includes parent ino and name hash.

 * Use this whenever possible, as it works more reliably.

 */

struct ceph_nfs_confh {

	u64 ino, parent_ino;

	u32 parent_name_hash;

} __attribute__ ((packed));



static int ceph_encode_fh(struct dentry *dentry, u32 *rawfh, int *max_len,

			  int connectable)

{

	struct ceph_nfs_fh *fh = (void *)rawfh;

	struct ceph_nfs_confh *cfh = (void *)rawfh;

	struct dentry *parent = dentry->d_parent;

	struct inode *inode = dentry->d_inode;

	int type;



	/* don't re-export snaps */

	if (ceph_snap(inode) != CEPH_NOSNAP)

		return -EINVAL;



	if (*max_len >= sizeof(*cfh)) {

		dout("encode_fh %p connectable\n", dentry);

		cfh->ino = ceph_ino(dentry->d_inode);

		cfh->parent_ino = ceph_ino(parent->d_inode);

		cfh->parent_name_hash = parent->d_name.hash;

		*max_len = sizeof(*cfh);

		type = 2;

	} else if (*max_len > sizeof(*fh)) {

		if (connectable)

			return -ENOSPC;

		dout("encode_fh %p\n", dentry);

		fh->ino = ceph_ino(dentry->d_inode);

		*max_len = sizeof(*fh);

		type = 1;

	} else {

		return -ENOSPC;

	}

	return type;

}



/*

 * convert regular fh to dentry

 *

 * FIXME: we should try harder by querying the mds for the ino.

 */

static struct dentry *__fh_to_dentry(struct super_block *sb,

				     struct ceph_nfs_fh *fh)

{

	struct inode *inode;

	struct dentry *dentry;

	struct ceph_vino vino;

	int err;



	dout("__fh_to_dentry %llx\n", fh->ino);

	vino.ino = fh->ino;

	vino.snap = CEPH_NOSNAP;

	inode = ceph_find_inode(sb, vino);

	if (!inode)

		return ERR_PTR(-ESTALE);



	dentry = d_obtain_alias(inode);

	if (!dentry) {

		pr_err("fh_to_dentry %llx -- inode %p but ENOMEM\n",

		       fh->ino, inode);

		iput(inode);

		return ERR_PTR(-ENOMEM);

	}

	err = ceph_init_dentry(dentry);



	if (err < 0) {

		iput(inode);

		return ERR_PTR(err);

	}

	dout("__fh_to_dentry %llx %p dentry %p\n", fh->ino, inode, dentry);

	return dentry;

}



/*

 * convert connectable fh to dentry

 */

static struct dentry *__cfh_to_dentry(struct super_block *sb,

				      struct ceph_nfs_confh *cfh)

{

	struct ceph_mds_client *mdsc = &ceph_client(sb)->mdsc;

	struct inode *inode;

	struct dentry *dentry;

	struct ceph_vino vino;

	int err;



	dout("__cfh_to_dentry %llx (%llx/%x)\n",

	     cfh->ino, cfh->parent_ino, cfh->parent_name_hash);



	vino.ino = cfh->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_LOOKUPHASH,

					       USE_ANY_MDS);

		if (IS_ERR(req))

			return ERR_PTR(PTR_ERR(req));



		req->r_ino1 = vino;

		req->r_ino2.ino = cfh->parent_ino;

		req->r_ino2.snap = CEPH_NOSNAP;

		req->r_path2 = kmalloc(16, GFP_NOFS);

		snprintf(req->r_path2, 16, "%d", cfh->parent_name_hash);

		req->r_num_caps = 1;

		err = ceph_mdsc_do_request(mdsc, NULL, req);

		ceph_mdsc_put_request(req);

		inode = ceph_find_inode(sb, vino);

		if (!inode)

			return ERR_PTR(err ? err : -ESTALE);

	}



	dentry = d_obtain_alias(inode);

	if (!dentry) {

		pr_err("cfh_to_dentry %llx -- inode %p but ENOMEM\n",

		       cfh->ino, inode);

		iput(inode);

		return ERR_PTR(-ENOMEM);

	}

	err = ceph_init_dentry(dentry);

	if (err < 0) {

		iput(inode);

		return ERR_PTR(err);

	}

	dout("__cfh_to_dentry %llx %p dentry %p\n", cfh->ino, inode, dentry);

	return dentry;

}



static struct dentry *ceph_fh_to_dentry(struct super_block *sb, struct fid *fid,

					int fh_len, int fh_type)

{

	if (fh_type == 1)

		return __fh_to_dentry(sb, (struct ceph_nfs_fh *)fid->raw);

	else

		return __cfh_to_dentry(sb, (struct ceph_nfs_confh *)fid->raw);

}



/*

 * 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);



	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 (!dentry) {

		pr_err("fh_to_parent %llx -- inode %p but ENOMEM\n",

		       cfh->ino, inode);

		iput(inode);

		return ERR_PTR(-ENOMEM);

	}

	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,

};