1 #include <linux/ceph/ceph_debug.h> 2 3 #include <linux/exportfs.h> 4 #include <linux/slab.h> 5 #include <asm/unaligned.h> 6 7 #include "super.h" 8 #include "mds_client.h" 9 10 /* 11 * NFS export support 12 * 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. 16 * 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 20 * ESTALE. 21 * 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. 25 */ 26 27 /* 28 * Basic fh 29 */ 30 struct ceph_nfs_fh { 31 u64 ino; 32 } __attribute__ ((packed)); 33 34 /* 35 * Larger 'connectable' fh that includes parent ino and name hash. 36 * Use this whenever possible, as it works more reliably. 37 */ 38 struct ceph_nfs_confh { 39 u64 ino, parent_ino; 40 u32 parent_name_hash; 41 } __attribute__ ((packed)); 42 43 /* 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. 50 */ 51 static int ceph_encode_fh(struct inode *inode, u32 *rawfh, int *max_len, 52 struct inode *parent_inode) 53 { 54 int type; 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; 61 62 /* don't re-export snaps */ 63 if (ceph_snap(inode) != CEPH_NOSNAP) 64 return -EINVAL; 65 66 dentry = d_find_alias(inode); 67 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, 76 dentry); 77 *max_len = connected_handle_length; 78 type = 2; 79 spin_unlock(&dentry->d_lock); 80 } else if (*max_len >= handle_length) { 81 if (parent_inode) { 82 /* nfsd wants connectable */ 83 *max_len = connected_handle_length; 84 type = FILEID_INVALID; 85 } else { 86 dout("encode_fh %p\n", dentry); 87 fh->ino = ceph_ino(inode); 88 *max_len = handle_length; 89 type = 1; 90 } 91 } else { 92 *max_len = handle_length; 93 type = FILEID_INVALID; 94 } 95 if (dentry) 96 dput(dentry); 97 return type; 98 } 99 100 /* 101 * convert regular fh to dentry 102 * 103 * FIXME: we should try harder by querying the mds for the ino. 104 */ 105 static struct dentry *__fh_to_dentry(struct super_block *sb, 106 struct ceph_nfs_fh *fh, int fh_len) 107 { 108 struct ceph_mds_client *mdsc = ceph_sb_to_client(sb)->mdsc; 109 struct inode *inode; 110 struct dentry *dentry; 111 struct ceph_vino vino; 112 int err; 113 114 if (fh_len < sizeof(*fh) / 4) 115 return ERR_PTR(-ESTALE); 116 117 dout("__fh_to_dentry %llx\n", fh->ino); 118 vino.ino = fh->ino; 119 vino.snap = CEPH_NOSNAP; 120 inode = ceph_find_inode(sb, vino); 121 if (!inode) { 122 struct ceph_mds_request *req; 123 124 req = ceph_mdsc_create_request(mdsc, CEPH_MDS_OP_LOOKUPINO, 125 USE_ANY_MDS); 126 if (IS_ERR(req)) 127 return ERR_CAST(req); 128 129 req->r_ino1 = vino; 130 req->r_num_caps = 1; 131 err = ceph_mdsc_do_request(mdsc, NULL, req); 132 inode = req->r_target_inode; 133 if (inode) 134 ihold(inode); 135 ceph_mdsc_put_request(req); 136 if (!inode) 137 return ERR_PTR(-ESTALE); 138 } 139 140 dentry = d_obtain_alias(inode); 141 if (IS_ERR(dentry)) { 142 pr_err("fh_to_dentry %llx -- inode %p but ENOMEM\n", 143 fh->ino, inode); 144 iput(inode); 145 return dentry; 146 } 147 err = ceph_init_dentry(dentry); 148 if (err < 0) { 149 iput(inode); 150 return ERR_PTR(err); 151 } 152 dout("__fh_to_dentry %llx %p dentry %p\n", fh->ino, inode, dentry); 153 return dentry; 154 } 155 156 /* 157 * convert connectable fh to dentry 158 */ 159 static struct dentry *__cfh_to_dentry(struct super_block *sb, 160 struct ceph_nfs_confh *cfh, int fh_len) 161 { 162 struct ceph_mds_client *mdsc = ceph_sb_to_client(sb)->mdsc; 163 struct inode *inode; 164 struct dentry *dentry; 165 struct ceph_vino vino; 166 int err; 167 168 if (fh_len < sizeof(*cfh) / 4) 169 return ERR_PTR(-ESTALE); 170 171 dout("__cfh_to_dentry %llx (%llx/%x)\n", 172 cfh->ino, cfh->parent_ino, cfh->parent_name_hash); 173 174 vino.ino = cfh->ino; 175 vino.snap = CEPH_NOSNAP; 176 inode = ceph_find_inode(sb, vino); 177 if (!inode) { 178 struct ceph_mds_request *req; 179 180 req = ceph_mdsc_create_request(mdsc, CEPH_MDS_OP_LOOKUPHASH, 181 USE_ANY_MDS); 182 if (IS_ERR(req)) 183 return ERR_CAST(req); 184 185 req->r_ino1 = vino; 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); 190 req->r_num_caps = 1; 191 err = ceph_mdsc_do_request(mdsc, NULL, req); 192 inode = req->r_target_inode; 193 if (inode) 194 ihold(inode); 195 ceph_mdsc_put_request(req); 196 if (!inode) 197 return ERR_PTR(err ? err : -ESTALE); 198 } 199 200 dentry = d_obtain_alias(inode); 201 if (IS_ERR(dentry)) { 202 pr_err("cfh_to_dentry %llx -- inode %p but ENOMEM\n", 203 cfh->ino, inode); 204 iput(inode); 205 return dentry; 206 } 207 err = ceph_init_dentry(dentry); 208 if (err < 0) { 209 iput(inode); 210 return ERR_PTR(err); 211 } 212 dout("__cfh_to_dentry %llx %p dentry %p\n", cfh->ino, inode, dentry); 213 return dentry; 214 } 215 216 static struct dentry *ceph_fh_to_dentry(struct super_block *sb, struct fid *fid, 217 int fh_len, int fh_type) 218 { 219 if (fh_type == 1) 220 return __fh_to_dentry(sb, (struct ceph_nfs_fh *)fid->raw, 221 fh_len); 222 else 223 return __cfh_to_dentry(sb, (struct ceph_nfs_confh *)fid->raw, 224 fh_len); 225 } 226 227 /* 228 * get parent, if possible. 229 * 230 * FIXME: we could do better by querying the mds to discover the 231 * parent. 232 */ 233 static struct dentry *ceph_fh_to_parent(struct super_block *sb, 234 struct fid *fid, 235 int fh_len, int fh_type) 236 { 237 struct ceph_nfs_confh *cfh = (void *)fid->raw; 238 struct ceph_vino vino; 239 struct inode *inode; 240 struct dentry *dentry; 241 int err; 242 243 if (fh_type == 1) 244 return ERR_PTR(-ESTALE); 245 if (fh_len < sizeof(*cfh) / 4) 246 return ERR_PTR(-ESTALE); 247 248 pr_debug("fh_to_parent %llx/%d\n", cfh->parent_ino, 249 cfh->parent_name_hash); 250 251 vino.ino = cfh->ino; 252 vino.snap = CEPH_NOSNAP; 253 inode = ceph_find_inode(sb, vino); 254 if (!inode) 255 return ERR_PTR(-ESTALE); 256 257 dentry = d_obtain_alias(inode); 258 if (IS_ERR(dentry)) { 259 pr_err("fh_to_parent %llx -- inode %p but ENOMEM\n", 260 cfh->ino, inode); 261 iput(inode); 262 return dentry; 263 } 264 err = ceph_init_dentry(dentry); 265 if (err < 0) { 266 iput(inode); 267 return ERR_PTR(err); 268 } 269 dout("fh_to_parent %llx %p dentry %p\n", cfh->ino, inode, dentry); 270 return dentry; 271 } 272 273 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, 277 }; 278