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 = d_find_alias(inode); 60 struct dentry *parent; 61 62 /* don't re-export snaps */ 63 if (ceph_snap(inode) != CEPH_NOSNAP) 64 return -EINVAL; 65 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, 74 dentry); 75 *max_len = connected_handle_length; 76 type = 2; 77 spin_unlock(&dentry->d_lock); 78 } else if (*max_len >= handle_length) { 79 if (parent_inode) { 80 /* nfsd wants connectable */ 81 *max_len = connected_handle_length; 82 type = 255; 83 } else { 84 dout("encode_fh %p\n", dentry); 85 fh->ino = ceph_ino(inode); 86 *max_len = handle_length; 87 type = 1; 88 } 89 } else { 90 *max_len = handle_length; 91 type = 255; 92 } 93 return type; 94 } 95 96 /* 97 * convert regular fh to dentry 98 * 99 * FIXME: we should try harder by querying the mds for the ino. 100 */ 101 static struct dentry *__fh_to_dentry(struct super_block *sb, 102 struct ceph_nfs_fh *fh) 103 { 104 struct ceph_mds_client *mdsc = ceph_sb_to_client(sb)->mdsc; 105 struct inode *inode; 106 struct dentry *dentry; 107 struct ceph_vino vino; 108 int err; 109 110 dout("__fh_to_dentry %llx\n", fh->ino); 111 vino.ino = fh->ino; 112 vino.snap = CEPH_NOSNAP; 113 inode = ceph_find_inode(sb, vino); 114 if (!inode) { 115 struct ceph_mds_request *req; 116 117 req = ceph_mdsc_create_request(mdsc, CEPH_MDS_OP_LOOKUPINO, 118 USE_ANY_MDS); 119 if (IS_ERR(req)) 120 return ERR_CAST(req); 121 122 req->r_ino1 = vino; 123 req->r_num_caps = 1; 124 err = ceph_mdsc_do_request(mdsc, NULL, req); 125 inode = req->r_target_inode; 126 if (inode) 127 ihold(inode); 128 ceph_mdsc_put_request(req); 129 if (!inode) 130 return ERR_PTR(-ESTALE); 131 } 132 133 dentry = d_obtain_alias(inode); 134 if (IS_ERR(dentry)) { 135 pr_err("fh_to_dentry %llx -- inode %p but ENOMEM\n", 136 fh->ino, inode); 137 iput(inode); 138 return dentry; 139 } 140 err = ceph_init_dentry(dentry); 141 if (err < 0) { 142 iput(inode); 143 return ERR_PTR(err); 144 } 145 dout("__fh_to_dentry %llx %p dentry %p\n", fh->ino, inode, dentry); 146 return dentry; 147 } 148 149 /* 150 * convert connectable fh to dentry 151 */ 152 static struct dentry *__cfh_to_dentry(struct super_block *sb, 153 struct ceph_nfs_confh *cfh) 154 { 155 struct ceph_mds_client *mdsc = ceph_sb_to_client(sb)->mdsc; 156 struct inode *inode; 157 struct dentry *dentry; 158 struct ceph_vino vino; 159 int err; 160 161 dout("__cfh_to_dentry %llx (%llx/%x)\n", 162 cfh->ino, cfh->parent_ino, cfh->parent_name_hash); 163 164 vino.ino = cfh->ino; 165 vino.snap = CEPH_NOSNAP; 166 inode = ceph_find_inode(sb, vino); 167 if (!inode) { 168 struct ceph_mds_request *req; 169 170 req = ceph_mdsc_create_request(mdsc, CEPH_MDS_OP_LOOKUPHASH, 171 USE_ANY_MDS); 172 if (IS_ERR(req)) 173 return ERR_CAST(req); 174 175 req->r_ino1 = vino; 176 req->r_ino2.ino = cfh->parent_ino; 177 req->r_ino2.snap = CEPH_NOSNAP; 178 req->r_path2 = kmalloc(16, GFP_NOFS); 179 snprintf(req->r_path2, 16, "%d", cfh->parent_name_hash); 180 req->r_num_caps = 1; 181 err = ceph_mdsc_do_request(mdsc, NULL, req); 182 inode = req->r_target_inode; 183 if (inode) 184 ihold(inode); 185 ceph_mdsc_put_request(req); 186 if (!inode) 187 return ERR_PTR(err ? err : -ESTALE); 188 } 189 190 dentry = d_obtain_alias(inode); 191 if (IS_ERR(dentry)) { 192 pr_err("cfh_to_dentry %llx -- inode %p but ENOMEM\n", 193 cfh->ino, inode); 194 iput(inode); 195 return dentry; 196 } 197 err = ceph_init_dentry(dentry); 198 if (err < 0) { 199 iput(inode); 200 return ERR_PTR(err); 201 } 202 dout("__cfh_to_dentry %llx %p dentry %p\n", cfh->ino, inode, dentry); 203 return dentry; 204 } 205 206 static struct dentry *ceph_fh_to_dentry(struct super_block *sb, struct fid *fid, 207 int fh_len, int fh_type) 208 { 209 if (fh_type == 1) 210 return __fh_to_dentry(sb, (struct ceph_nfs_fh *)fid->raw); 211 else 212 return __cfh_to_dentry(sb, (struct ceph_nfs_confh *)fid->raw); 213 } 214 215 /* 216 * get parent, if possible. 217 * 218 * FIXME: we could do better by querying the mds to discover the 219 * parent. 220 */ 221 static struct dentry *ceph_fh_to_parent(struct super_block *sb, 222 struct fid *fid, 223 int fh_len, int fh_type) 224 { 225 struct ceph_nfs_confh *cfh = (void *)fid->raw; 226 struct ceph_vino vino; 227 struct inode *inode; 228 struct dentry *dentry; 229 int err; 230 231 if (fh_type == 1) 232 return ERR_PTR(-ESTALE); 233 234 pr_debug("fh_to_parent %llx/%d\n", cfh->parent_ino, 235 cfh->parent_name_hash); 236 237 vino.ino = cfh->ino; 238 vino.snap = CEPH_NOSNAP; 239 inode = ceph_find_inode(sb, vino); 240 if (!inode) 241 return ERR_PTR(-ESTALE); 242 243 dentry = d_obtain_alias(inode); 244 if (IS_ERR(dentry)) { 245 pr_err("fh_to_parent %llx -- inode %p but ENOMEM\n", 246 cfh->ino, inode); 247 iput(inode); 248 return dentry; 249 } 250 err = ceph_init_dentry(dentry); 251 if (err < 0) { 252 iput(inode); 253 return ERR_PTR(err); 254 } 255 dout("fh_to_parent %llx %p dentry %p\n", cfh->ino, inode, dentry); 256 return dentry; 257 } 258 259 const struct export_operations ceph_export_ops = { 260 .encode_fh = ceph_encode_fh, 261 .fh_to_dentry = ceph_fh_to_dentry, 262 .fh_to_parent = ceph_fh_to_parent, 263 }; 264