1 #include <linux/ceph/ceph_debug.h>
3 #include <linux/exportfs.h>
4 #include <linux/slab.h>
5 #include <asm/unaligned.h>
8 #include "mds_client.h"
13 * NFS re-export of a ceph mount is, at present, only semireliable.
14 * The basic issue is that the Ceph architectures doesn't lend itself
15 * well to generating filehandles that will remain valid forever.
17 * So, we do our best. If you're lucky, your inode will be in the
18 * client's cache. If it's not, and you have a connectable fh, then
19 * the MDS server may be able to find it for you. Otherwise, you get
22 * There are ways to this more reliable, but in the non-connectable fh
23 * case, we won't every work perfectly, and in the connectable case,
24 * some changes are needed on the MDS side to work better.
32 } __attribute__ ((packed));
35 * Larger 'connectable' fh that includes parent ino and name hash.
36 * Use this whenever possible, as it works more reliably.
38 struct ceph_nfs_confh {
41 } __attribute__ ((packed));
44 * The presence of @parent_inode here tells us whether NFS wants a
45 * connectable file handle. However, we want to make a connectionable
46 * file handle unconditionally so that the MDS gets as much of a hint
47 * as possible. That means we only use @parent_dentry to indicate
48 * whether nfsd wants a connectable fh, and whether we should indicate
49 * failure from a too-small @max_len.
51 static int ceph_encode_fh(struct inode *inode, u32 *rawfh, int *max_len,
52 struct inode *parent_inode)
55 struct ceph_nfs_fh *fh = (void *)rawfh;
56 struct ceph_nfs_confh *cfh = (void *)rawfh;
57 int connected_handle_length = sizeof(*cfh)/4;
58 int handle_length = sizeof(*fh)/4;
59 struct dentry *dentry;
60 struct dentry *parent;
62 /* don't re-export snaps */
63 if (ceph_snap(inode) != CEPH_NOSNAP)
66 dentry = d_find_alias(inode);
68 /* if we found an alias, generate a connectable fh */
69 if (*max_len >= connected_handle_length && dentry) {
70 dout("encode_fh %p connectable\n", dentry);
71 spin_lock(&dentry->d_lock);
72 parent = dentry->d_parent;
73 cfh->ino = ceph_ino(inode);
74 cfh->parent_ino = ceph_ino(parent->d_inode);
75 cfh->parent_name_hash = ceph_dentry_hash(parent->d_inode,
77 *max_len = connected_handle_length;
79 spin_unlock(&dentry->d_lock);
80 } else if (*max_len >= handle_length) {
82 /* nfsd wants connectable */
83 *max_len = connected_handle_length;
86 dout("encode_fh %p\n", dentry);
87 fh->ino = ceph_ino(inode);
88 *max_len = handle_length;
92 *max_len = handle_length;
101 * convert regular fh to dentry
103 * FIXME: we should try harder by querying the mds for the ino.
105 static struct dentry *__fh_to_dentry(struct super_block *sb,
106 struct ceph_nfs_fh *fh, int fh_len)
108 struct ceph_mds_client *mdsc = ceph_sb_to_client(sb)->mdsc;
110 struct dentry *dentry;
111 struct ceph_vino vino;
114 if (fh_len < sizeof(*fh) / 4)
115 return ERR_PTR(-ESTALE);
117 dout("__fh_to_dentry %llx\n", fh->ino);
119 vino.snap = CEPH_NOSNAP;
120 inode = ceph_find_inode(sb, vino);
122 struct ceph_mds_request *req;
124 req = ceph_mdsc_create_request(mdsc, CEPH_MDS_OP_LOOKUPINO,
127 return ERR_CAST(req);
131 err = ceph_mdsc_do_request(mdsc, NULL, req);
132 inode = req->r_target_inode;
135 ceph_mdsc_put_request(req);
137 return ERR_PTR(-ESTALE);
140 dentry = d_obtain_alias(inode);
141 if (IS_ERR(dentry)) {
142 pr_err("fh_to_dentry %llx -- inode %p but ENOMEM\n",
147 err = ceph_init_dentry(dentry);
152 dout("__fh_to_dentry %llx %p dentry %p\n", fh->ino, inode, dentry);
157 * convert connectable fh to dentry
159 static struct dentry *__cfh_to_dentry(struct super_block *sb,
160 struct ceph_nfs_confh *cfh, int fh_len)
162 struct ceph_mds_client *mdsc = ceph_sb_to_client(sb)->mdsc;
164 struct dentry *dentry;
165 struct ceph_vino vino;
168 if (fh_len < sizeof(*cfh) / 4)
169 return ERR_PTR(-ESTALE);
171 dout("__cfh_to_dentry %llx (%llx/%x)\n",
172 cfh->ino, cfh->parent_ino, cfh->parent_name_hash);
175 vino.snap = CEPH_NOSNAP;
176 inode = ceph_find_inode(sb, vino);
178 struct ceph_mds_request *req;
180 req = ceph_mdsc_create_request(mdsc, CEPH_MDS_OP_LOOKUPHASH,
183 return ERR_CAST(req);
186 req->r_ino2.ino = cfh->parent_ino;
187 req->r_ino2.snap = CEPH_NOSNAP;
188 req->r_path2 = kmalloc(16, GFP_NOFS);
189 snprintf(req->r_path2, 16, "%d", cfh->parent_name_hash);
191 err = ceph_mdsc_do_request(mdsc, NULL, req);
192 inode = req->r_target_inode;
195 ceph_mdsc_put_request(req);
197 return ERR_PTR(err ? err : -ESTALE);
200 dentry = d_obtain_alias(inode);
201 if (IS_ERR(dentry)) {
202 pr_err("cfh_to_dentry %llx -- inode %p but ENOMEM\n",
207 err = ceph_init_dentry(dentry);
212 dout("__cfh_to_dentry %llx %p dentry %p\n", cfh->ino, inode, dentry);
216 static struct dentry *ceph_fh_to_dentry(struct super_block *sb, struct fid *fid,
217 int fh_len, int fh_type)
220 return __fh_to_dentry(sb, (struct ceph_nfs_fh *)fid->raw,
223 return __cfh_to_dentry(sb, (struct ceph_nfs_confh *)fid->raw,
228 * get parent, if possible.
230 * FIXME: we could do better by querying the mds to discover the
233 static struct dentry *ceph_fh_to_parent(struct super_block *sb,
235 int fh_len, int fh_type)
237 struct ceph_nfs_confh *cfh = (void *)fid->raw;
238 struct ceph_vino vino;
240 struct dentry *dentry;
244 return ERR_PTR(-ESTALE);
245 if (fh_len < sizeof(*cfh) / 4)
246 return ERR_PTR(-ESTALE);
248 pr_debug("fh_to_parent %llx/%d\n", cfh->parent_ino,
249 cfh->parent_name_hash);
252 vino.snap = CEPH_NOSNAP;
253 inode = ceph_find_inode(sb, vino);
255 return ERR_PTR(-ESTALE);
257 dentry = d_obtain_alias(inode);
258 if (IS_ERR(dentry)) {
259 pr_err("fh_to_parent %llx -- inode %p but ENOMEM\n",
264 err = ceph_init_dentry(dentry);
269 dout("fh_to_parent %llx %p dentry %p\n", cfh->ino, inode, dentry);
273 const struct export_operations ceph_export_ops = {
274 .encode_fh = ceph_encode_fh,
275 .fh_to_dentry = ceph_fh_to_dentry,
276 .fh_to_parent = ceph_fh_to_parent,