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: Sage Weil <sage@newdream.net>
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Sage Weil
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8fc91fd859
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223
fs/ceph/export.c
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223
fs/ceph/export.c
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#include "ceph_debug.h"
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#include <linux/exportfs.h>
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#include <asm/unaligned.h>
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#include "super.h"
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/*
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* NFS export support
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*
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* NFS re-export of a ceph mount is, at present, only semireliable.
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* The basic issue is that the Ceph architectures doesn't lend itself
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* well to generating filehandles that will remain valid forever.
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*
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* So, we do our best. If you're lucky, your inode will be in the
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* client's cache. If it's not, and you have a connectable fh, then
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* the MDS server may be able to find it for you. Otherwise, you get
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* ESTALE.
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*
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* There are ways to this more reliable, but in the non-connectable fh
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* case, we won't every work perfectly, and in the connectable case,
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* some changes are needed on the MDS side to work better.
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*/
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/*
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* Basic fh
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*/
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struct ceph_nfs_fh {
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u64 ino;
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} __attribute__ ((packed));
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/*
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* Larger 'connectable' fh that includes parent ino and name hash.
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* Use this whenever possible, as it works more reliably.
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*/
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struct ceph_nfs_confh {
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u64 ino, parent_ino;
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u32 parent_name_hash;
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} __attribute__ ((packed));
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static int ceph_encode_fh(struct dentry *dentry, u32 *rawfh, int *max_len,
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int connectable)
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{
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struct ceph_nfs_fh *fh = (void *)rawfh;
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struct ceph_nfs_confh *cfh = (void *)rawfh;
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struct dentry *parent = dentry->d_parent;
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struct inode *inode = dentry->d_inode;
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int type;
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/* don't re-export snaps */
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if (ceph_snap(inode) != CEPH_NOSNAP)
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return -EINVAL;
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if (*max_len >= sizeof(*cfh)) {
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dout("encode_fh %p connectable\n", dentry);
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cfh->ino = ceph_ino(dentry->d_inode);
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cfh->parent_ino = ceph_ino(parent->d_inode);
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cfh->parent_name_hash = parent->d_name.hash;
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*max_len = sizeof(*cfh);
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type = 2;
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} else if (*max_len > sizeof(*fh)) {
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if (connectable)
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return -ENOSPC;
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dout("encode_fh %p\n", dentry);
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fh->ino = ceph_ino(dentry->d_inode);
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*max_len = sizeof(*fh);
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type = 1;
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} else {
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return -ENOSPC;
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}
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return type;
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}
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/*
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* convert regular fh to dentry
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*
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* FIXME: we should try harder by querying the mds for the ino.
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*/
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static struct dentry *__fh_to_dentry(struct super_block *sb,
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struct ceph_nfs_fh *fh)
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{
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struct inode *inode;
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struct dentry *dentry;
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struct ceph_vino vino;
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int err;
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dout("__fh_to_dentry %llx\n", fh->ino);
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vino.ino = fh->ino;
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vino.snap = CEPH_NOSNAP;
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inode = ceph_find_inode(sb, vino);
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if (!inode)
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return ERR_PTR(-ESTALE);
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dentry = d_obtain_alias(inode);
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if (!dentry) {
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pr_err("fh_to_dentry %llx -- inode %p but ENOMEM\n",
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fh->ino, inode);
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iput(inode);
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return ERR_PTR(-ENOMEM);
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}
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err = ceph_init_dentry(dentry);
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if (err < 0) {
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iput(inode);
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return ERR_PTR(err);
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}
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dout("__fh_to_dentry %llx %p dentry %p\n", fh->ino, inode, dentry);
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return dentry;
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}
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/*
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* convert connectable fh to dentry
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*/
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static struct dentry *__cfh_to_dentry(struct super_block *sb,
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struct ceph_nfs_confh *cfh)
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{
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struct ceph_mds_client *mdsc = &ceph_client(sb)->mdsc;
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struct inode *inode;
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struct dentry *dentry;
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struct ceph_vino vino;
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int err;
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dout("__cfh_to_dentry %llx (%llx/%x)\n",
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cfh->ino, cfh->parent_ino, cfh->parent_name_hash);
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vino.ino = cfh->ino;
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vino.snap = CEPH_NOSNAP;
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inode = ceph_find_inode(sb, vino);
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if (!inode) {
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struct ceph_mds_request *req;
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req = ceph_mdsc_create_request(mdsc, CEPH_MDS_OP_LOOKUPHASH,
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USE_ANY_MDS);
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if (IS_ERR(req))
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return ERR_PTR(PTR_ERR(req));
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req->r_ino1 = vino;
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req->r_ino2.ino = cfh->parent_ino;
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req->r_ino2.snap = CEPH_NOSNAP;
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req->r_path2 = kmalloc(16, GFP_NOFS);
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snprintf(req->r_path2, 16, "%d", cfh->parent_name_hash);
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req->r_num_caps = 1;
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err = ceph_mdsc_do_request(mdsc, NULL, req);
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ceph_mdsc_put_request(req);
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inode = ceph_find_inode(sb, vino);
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if (!inode)
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return ERR_PTR(err ? err : -ESTALE);
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}
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dentry = d_obtain_alias(inode);
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if (!dentry) {
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pr_err("cfh_to_dentry %llx -- inode %p but ENOMEM\n",
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cfh->ino, inode);
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iput(inode);
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return ERR_PTR(-ENOMEM);
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}
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err = ceph_init_dentry(dentry);
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if (err < 0) {
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iput(inode);
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return ERR_PTR(err);
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}
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dout("__cfh_to_dentry %llx %p dentry %p\n", cfh->ino, inode, dentry);
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return dentry;
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}
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static struct dentry *ceph_fh_to_dentry(struct super_block *sb, struct fid *fid,
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int fh_len, int fh_type)
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{
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if (fh_type == 1)
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return __fh_to_dentry(sb, (struct ceph_nfs_fh *)fid->raw);
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else
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return __cfh_to_dentry(sb, (struct ceph_nfs_confh *)fid->raw);
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}
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/*
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* get parent, if possible.
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*
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* FIXME: we could do better by querying the mds to discover the
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* parent.
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*/
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static struct dentry *ceph_fh_to_parent(struct super_block *sb,
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struct fid *fid,
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int fh_len, int fh_type)
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{
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struct ceph_nfs_confh *cfh = (void *)fid->raw;
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struct ceph_vino vino;
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struct inode *inode;
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struct dentry *dentry;
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int err;
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if (fh_type == 1)
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return ERR_PTR(-ESTALE);
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pr_debug("fh_to_parent %llx/%d\n", cfh->parent_ino,
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cfh->parent_name_hash);
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vino.ino = cfh->ino;
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vino.snap = CEPH_NOSNAP;
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inode = ceph_find_inode(sb, vino);
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if (!inode)
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return ERR_PTR(-ESTALE);
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dentry = d_obtain_alias(inode);
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if (!dentry) {
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pr_err("fh_to_parent %llx -- inode %p but ENOMEM\n",
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cfh->ino, inode);
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iput(inode);
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return ERR_PTR(-ENOMEM);
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}
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err = ceph_init_dentry(dentry);
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if (err < 0) {
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iput(inode);
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return ERR_PTR(err);
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}
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dout("fh_to_parent %llx %p dentry %p\n", cfh->ino, inode, dentry);
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return dentry;
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}
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const struct export_operations ceph_export_ops = {
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.encode_fh = ceph_encode_fh,
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.fh_to_dentry = ceph_fh_to_dentry,
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.fh_to_parent = ceph_fh_to_parent,
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};
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