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 = d_find_alias(inode);
60 struct dentry *parent;
62 /* don't re-export snaps */
63 if (ceph_snap(inode) != CEPH_NOSNAP)
66 /* if we found an alias, generate a connectable fh */
67 if (*max_len >= connected_handle_length && dentry) {
68 dout("encode_fh %p connectable\n", dentry);
69 spin_lock(&dentry->d_lock);
70 parent = dentry->d_parent;
71 cfh->ino = ceph_ino(inode);
72 cfh->parent_ino = ceph_ino(parent->d_inode);
73 cfh->parent_name_hash = ceph_dentry_hash(parent->d_inode,
75 *max_len = connected_handle_length;
77 spin_unlock(&dentry->d_lock);
78 } else if (*max_len >= handle_length) {
80 /* nfsd wants connectable */
81 *max_len = connected_handle_length;
84 dout("encode_fh %p\n", dentry);
85 fh->ino = ceph_ino(inode);
86 *max_len = handle_length;
90 *max_len = handle_length;
99 * convert regular fh to dentry
101 * FIXME: we should try harder by querying the mds for the ino.
103 static struct dentry *__fh_to_dentry(struct super_block *sb,
104 struct ceph_nfs_fh *fh)
106 struct ceph_mds_client *mdsc = ceph_sb_to_client(sb)->mdsc;
108 struct dentry *dentry;
109 struct ceph_vino vino;
112 dout("__fh_to_dentry %llx\n", fh->ino);
114 vino.snap = CEPH_NOSNAP;
115 inode = ceph_find_inode(sb, vino);
117 struct ceph_mds_request *req;
119 req = ceph_mdsc_create_request(mdsc, CEPH_MDS_OP_LOOKUPINO,
122 return ERR_CAST(req);
126 err = ceph_mdsc_do_request(mdsc, NULL, req);
127 inode = req->r_target_inode;
130 ceph_mdsc_put_request(req);
132 return ERR_PTR(-ESTALE);
135 dentry = d_obtain_alias(inode);
136 if (IS_ERR(dentry)) {
137 pr_err("fh_to_dentry %llx -- inode %p but ENOMEM\n",
142 err = ceph_init_dentry(dentry);
147 dout("__fh_to_dentry %llx %p dentry %p\n", fh->ino, inode, dentry);
152 * convert connectable fh to dentry
154 static struct dentry *__cfh_to_dentry(struct super_block *sb,
155 struct ceph_nfs_confh *cfh)
157 struct ceph_mds_client *mdsc = ceph_sb_to_client(sb)->mdsc;
159 struct dentry *dentry;
160 struct ceph_vino vino;
163 dout("__cfh_to_dentry %llx (%llx/%x)\n",
164 cfh->ino, cfh->parent_ino, cfh->parent_name_hash);
167 vino.snap = CEPH_NOSNAP;
168 inode = ceph_find_inode(sb, vino);
170 struct ceph_mds_request *req;
172 req = ceph_mdsc_create_request(mdsc, CEPH_MDS_OP_LOOKUPHASH,
175 return ERR_CAST(req);
178 req->r_ino2.ino = cfh->parent_ino;
179 req->r_ino2.snap = CEPH_NOSNAP;
180 req->r_path2 = kmalloc(16, GFP_NOFS);
181 snprintf(req->r_path2, 16, "%d", cfh->parent_name_hash);
183 err = ceph_mdsc_do_request(mdsc, NULL, req);
184 inode = req->r_target_inode;
187 ceph_mdsc_put_request(req);
189 return ERR_PTR(err ? err : -ESTALE);
192 dentry = d_obtain_alias(inode);
193 if (IS_ERR(dentry)) {
194 pr_err("cfh_to_dentry %llx -- inode %p but ENOMEM\n",
199 err = ceph_init_dentry(dentry);
204 dout("__cfh_to_dentry %llx %p dentry %p\n", cfh->ino, inode, dentry);
208 static struct dentry *ceph_fh_to_dentry(struct super_block *sb, struct fid *fid,
209 int fh_len, int fh_type)
212 return __fh_to_dentry(sb, (struct ceph_nfs_fh *)fid->raw);
214 return __cfh_to_dentry(sb, (struct ceph_nfs_confh *)fid->raw);
218 * get parent, if possible.
220 * FIXME: we could do better by querying the mds to discover the
223 static struct dentry *ceph_fh_to_parent(struct super_block *sb,
225 int fh_len, int fh_type)
227 struct ceph_nfs_confh *cfh = (void *)fid->raw;
228 struct ceph_vino vino;
230 struct dentry *dentry;
234 return ERR_PTR(-ESTALE);
236 pr_debug("fh_to_parent %llx/%d\n", cfh->parent_ino,
237 cfh->parent_name_hash);
240 vino.snap = CEPH_NOSNAP;
241 inode = ceph_find_inode(sb, vino);
243 return ERR_PTR(-ESTALE);
245 dentry = d_obtain_alias(inode);
246 if (IS_ERR(dentry)) {
247 pr_err("fh_to_parent %llx -- inode %p but ENOMEM\n",
252 err = ceph_init_dentry(dentry);
257 dout("fh_to_parent %llx %p dentry %p\n", cfh->ino, inode, dentry);
261 const struct export_operations ceph_export_ops = {
262 .encode_fh = ceph_encode_fh,
263 .fh_to_dentry = ceph_fh_to_dentry,
264 .fh_to_parent = ceph_fh_to_parent,