#include "ceph_debug.h"
#include <linux/exportfs.h>
#include <linux/slab.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)
{
int type;
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 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 (*max_len >= connected_handle_length) {
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 = connected_handle_length;
type = 2;
} else if (*max_len >= handle_length) {
if (connectable) {
*max_len = connected_handle_length;
return 255;
}
dout("encode_fh %p\n", dentry);
fh->ino = ceph_ino(dentry->d_inode);
*max_len = handle_length;
type = 1;
} else {
*max_len = handle_length;
return 255;
}
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 (IS_ERR(dentry)) {
pr_err("fh_to_dentry %llx -- inode %p but ENOMEM\n",
fh->ino, inode);
iput(inode);
return dentry;
}
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_sb_to_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_CAST(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 (IS_ERR(dentry)) {
pr_err("cfh_to_dentry %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("__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 (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,
};
