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 static int ceph_encode_fh(struct dentry *dentry, u32 *rawfh, int *max_len, 44 int connectable) 45 { 46 int type; 47 struct ceph_nfs_fh *fh = (void *)rawfh; 48 struct ceph_nfs_confh *cfh = (void *)rawfh; 49 struct dentry *parent = dentry->d_parent; 50 struct inode *inode = dentry->d_inode; 51 int connected_handle_length = sizeof(*cfh)/4; 52 int handle_length = sizeof(*fh)/4; 53 54 /* don't re-export snaps */ 55 if (ceph_snap(inode) != CEPH_NOSNAP) 56 return -EINVAL; 57 58 if (*max_len >= connected_handle_length) { 59 dout("encode_fh %p connectable\n", dentry); 60 cfh->ino = ceph_ino(dentry->d_inode); 61 cfh->parent_ino = ceph_ino(parent->d_inode); 62 cfh->parent_name_hash = parent->d_name.hash; 63 *max_len = connected_handle_length; 64 type = 2; 65 } else if (*max_len >= handle_length) { 66 if (connectable) { 67 *max_len = connected_handle_length; 68 return 255; 69 } 70 dout("encode_fh %p\n", dentry); 71 fh->ino = ceph_ino(dentry->d_inode); 72 *max_len = handle_length; 73 type = 1; 74 } else { 75 *max_len = handle_length; 76 return 255; 77 } 78 return type; 79 } 80 81 /* 82 * convert regular fh to dentry 83 * 84 * FIXME: we should try harder by querying the mds for the ino. 85 */ 86 static struct dentry *__fh_to_dentry(struct super_block *sb, 87 struct ceph_nfs_fh *fh) 88 { 89 struct inode *inode; 90 struct dentry *dentry; 91 struct ceph_vino vino; 92 int err; 93 94 dout("__fh_to_dentry %llx\n", fh->ino); 95 vino.ino = fh->ino; 96 vino.snap = CEPH_NOSNAP; 97 inode = ceph_find_inode(sb, vino); 98 if (!inode) 99 return ERR_PTR(-ESTALE); 100 101 dentry = d_obtain_alias(inode); 102 if (IS_ERR(dentry)) { 103 pr_err("fh_to_dentry %llx -- inode %p but ENOMEM\n", 104 fh->ino, inode); 105 iput(inode); 106 return dentry; 107 } 108 err = ceph_init_dentry(dentry); 109 110 if (err < 0) { 111 iput(inode); 112 return ERR_PTR(err); 113 } 114 dout("__fh_to_dentry %llx %p dentry %p\n", fh->ino, inode, dentry); 115 return dentry; 116 } 117 118 /* 119 * convert connectable fh to dentry 120 */ 121 static struct dentry *__cfh_to_dentry(struct super_block *sb, 122 struct ceph_nfs_confh *cfh) 123 { 124 struct ceph_mds_client *mdsc = ceph_sb_to_client(sb)->mdsc; 125 struct inode *inode; 126 struct dentry *dentry; 127 struct ceph_vino vino; 128 int err; 129 130 dout("__cfh_to_dentry %llx (%llx/%x)\n", 131 cfh->ino, cfh->parent_ino, cfh->parent_name_hash); 132 133 vino.ino = cfh->ino; 134 vino.snap = CEPH_NOSNAP; 135 inode = ceph_find_inode(sb, vino); 136 if (!inode) { 137 struct ceph_mds_request *req; 138 139 req = ceph_mdsc_create_request(mdsc, CEPH_MDS_OP_LOOKUPHASH, 140 USE_ANY_MDS); 141 if (IS_ERR(req)) 142 return ERR_CAST(req); 143 144 req->r_ino1 = vino; 145 req->r_ino2.ino = cfh->parent_ino; 146 req->r_ino2.snap = CEPH_NOSNAP; 147 req->r_path2 = kmalloc(16, GFP_NOFS); 148 snprintf(req->r_path2, 16, "%d", cfh->parent_name_hash); 149 req->r_num_caps = 1; 150 err = ceph_mdsc_do_request(mdsc, NULL, req); 151 ceph_mdsc_put_request(req); 152 inode = ceph_find_inode(sb, vino); 153 if (!inode) 154 return ERR_PTR(err ? err : -ESTALE); 155 } 156 157 dentry = d_obtain_alias(inode); 158 if (IS_ERR(dentry)) { 159 pr_err("cfh_to_dentry %llx -- inode %p but ENOMEM\n", 160 cfh->ino, inode); 161 iput(inode); 162 return dentry; 163 } 164 err = ceph_init_dentry(dentry); 165 if (err < 0) { 166 iput(inode); 167 return ERR_PTR(err); 168 } 169 dout("__cfh_to_dentry %llx %p dentry %p\n", cfh->ino, inode, dentry); 170 return dentry; 171 } 172 173 static struct dentry *ceph_fh_to_dentry(struct super_block *sb, struct fid *fid, 174 int fh_len, int fh_type) 175 { 176 if (fh_type == 1) 177 return __fh_to_dentry(sb, (struct ceph_nfs_fh *)fid->raw); 178 else 179 return __cfh_to_dentry(sb, (struct ceph_nfs_confh *)fid->raw); 180 } 181 182 /* 183 * get parent, if possible. 184 * 185 * FIXME: we could do better by querying the mds to discover the 186 * parent. 187 */ 188 static struct dentry *ceph_fh_to_parent(struct super_block *sb, 189 struct fid *fid, 190 int fh_len, int fh_type) 191 { 192 struct ceph_nfs_confh *cfh = (void *)fid->raw; 193 struct ceph_vino vino; 194 struct inode *inode; 195 struct dentry *dentry; 196 int err; 197 198 if (fh_type == 1) 199 return ERR_PTR(-ESTALE); 200 201 pr_debug("fh_to_parent %llx/%d\n", cfh->parent_ino, 202 cfh->parent_name_hash); 203 204 vino.ino = cfh->ino; 205 vino.snap = CEPH_NOSNAP; 206 inode = ceph_find_inode(sb, vino); 207 if (!inode) 208 return ERR_PTR(-ESTALE); 209 210 dentry = d_obtain_alias(inode); 211 if (IS_ERR(dentry)) { 212 pr_err("fh_to_parent %llx -- inode %p but ENOMEM\n", 213 cfh->ino, inode); 214 iput(inode); 215 return dentry; 216 } 217 err = ceph_init_dentry(dentry); 218 if (err < 0) { 219 iput(inode); 220 return ERR_PTR(err); 221 } 222 dout("fh_to_parent %llx %p dentry %p\n", cfh->ino, inode, dentry); 223 return dentry; 224 } 225 226 const struct export_operations ceph_export_ops = { 227 .encode_fh = ceph_encode_fh, 228 .fh_to_dentry = ceph_fh_to_dentry, 229 .fh_to_parent = ceph_fh_to_parent, 230 }; 231