1 #include "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 9 /* 10 * NFS export support 11 * 12 * NFS re-export of a ceph mount is, at present, only semireliable. 13 * The basic issue is that the Ceph architectures doesn't lend itself 14 * well to generating filehandles that will remain valid forever. 15 * 16 * So, we do our best. If you're lucky, your inode will be in the 17 * client's cache. If it's not, and you have a connectable fh, then 18 * the MDS server may be able to find it for you. Otherwise, you get 19 * ESTALE. 20 * 21 * There are ways to this more reliable, but in the non-connectable fh 22 * case, we won't every work perfectly, and in the connectable case, 23 * some changes are needed on the MDS side to work better. 24 */ 25 26 /* 27 * Basic fh 28 */ 29 struct ceph_nfs_fh { 30 u64 ino; 31 } __attribute__ ((packed)); 32 33 /* 34 * Larger 'connectable' fh that includes parent ino and name hash. 35 * Use this whenever possible, as it works more reliably. 36 */ 37 struct ceph_nfs_confh { 38 u64 ino, parent_ino; 39 u32 parent_name_hash; 40 } __attribute__ ((packed)); 41 42 static int ceph_encode_fh(struct dentry *dentry, u32 *rawfh, int *max_len, 43 int connectable) 44 { 45 struct ceph_nfs_fh *fh = (void *)rawfh; 46 struct ceph_nfs_confh *cfh = (void *)rawfh; 47 struct dentry *parent = dentry->d_parent; 48 struct inode *inode = dentry->d_inode; 49 int type; 50 51 /* don't re-export snaps */ 52 if (ceph_snap(inode) != CEPH_NOSNAP) 53 return -EINVAL; 54 55 if (*max_len >= sizeof(*cfh)) { 56 dout("encode_fh %p connectable\n", dentry); 57 cfh->ino = ceph_ino(dentry->d_inode); 58 cfh->parent_ino = ceph_ino(parent->d_inode); 59 cfh->parent_name_hash = parent->d_name.hash; 60 *max_len = sizeof(*cfh); 61 type = 2; 62 } else if (*max_len > sizeof(*fh)) { 63 if (connectable) 64 return -ENOSPC; 65 dout("encode_fh %p\n", dentry); 66 fh->ino = ceph_ino(dentry->d_inode); 67 *max_len = sizeof(*fh); 68 type = 1; 69 } else { 70 return -ENOSPC; 71 } 72 return type; 73 } 74 75 /* 76 * convert regular fh to dentry 77 * 78 * FIXME: we should try harder by querying the mds for the ino. 79 */ 80 static struct dentry *__fh_to_dentry(struct super_block *sb, 81 struct ceph_nfs_fh *fh) 82 { 83 struct inode *inode; 84 struct dentry *dentry; 85 struct ceph_vino vino; 86 int err; 87 88 dout("__fh_to_dentry %llx\n", fh->ino); 89 vino.ino = fh->ino; 90 vino.snap = CEPH_NOSNAP; 91 inode = ceph_find_inode(sb, vino); 92 if (!inode) 93 return ERR_PTR(-ESTALE); 94 95 dentry = d_obtain_alias(inode); 96 if (!dentry) { 97 pr_err("fh_to_dentry %llx -- inode %p but ENOMEM\n", 98 fh->ino, inode); 99 iput(inode); 100 return ERR_PTR(-ENOMEM); 101 } 102 err = ceph_init_dentry(dentry); 103 104 if (err < 0) { 105 iput(inode); 106 return ERR_PTR(err); 107 } 108 dout("__fh_to_dentry %llx %p dentry %p\n", fh->ino, inode, dentry); 109 return dentry; 110 } 111 112 /* 113 * convert connectable fh to dentry 114 */ 115 static struct dentry *__cfh_to_dentry(struct super_block *sb, 116 struct ceph_nfs_confh *cfh) 117 { 118 struct ceph_mds_client *mdsc = &ceph_client(sb)->mdsc; 119 struct inode *inode; 120 struct dentry *dentry; 121 struct ceph_vino vino; 122 int err; 123 124 dout("__cfh_to_dentry %llx (%llx/%x)\n", 125 cfh->ino, cfh->parent_ino, cfh->parent_name_hash); 126 127 vino.ino = cfh->ino; 128 vino.snap = CEPH_NOSNAP; 129 inode = ceph_find_inode(sb, vino); 130 if (!inode) { 131 struct ceph_mds_request *req; 132 133 req = ceph_mdsc_create_request(mdsc, CEPH_MDS_OP_LOOKUPHASH, 134 USE_ANY_MDS); 135 if (IS_ERR(req)) 136 return ERR_PTR(PTR_ERR(req)); 137 138 req->r_ino1 = vino; 139 req->r_ino2.ino = cfh->parent_ino; 140 req->r_ino2.snap = CEPH_NOSNAP; 141 req->r_path2 = kmalloc(16, GFP_NOFS); 142 snprintf(req->r_path2, 16, "%d", cfh->parent_name_hash); 143 req->r_num_caps = 1; 144 err = ceph_mdsc_do_request(mdsc, NULL, req); 145 ceph_mdsc_put_request(req); 146 inode = ceph_find_inode(sb, vino); 147 if (!inode) 148 return ERR_PTR(err ? err : -ESTALE); 149 } 150 151 dentry = d_obtain_alias(inode); 152 if (!dentry) { 153 pr_err("cfh_to_dentry %llx -- inode %p but ENOMEM\n", 154 cfh->ino, inode); 155 iput(inode); 156 return ERR_PTR(-ENOMEM); 157 } 158 err = ceph_init_dentry(dentry); 159 if (err < 0) { 160 iput(inode); 161 return ERR_PTR(err); 162 } 163 dout("__cfh_to_dentry %llx %p dentry %p\n", cfh->ino, inode, dentry); 164 return dentry; 165 } 166 167 static struct dentry *ceph_fh_to_dentry(struct super_block *sb, struct fid *fid, 168 int fh_len, int fh_type) 169 { 170 if (fh_type == 1) 171 return __fh_to_dentry(sb, (struct ceph_nfs_fh *)fid->raw); 172 else 173 return __cfh_to_dentry(sb, (struct ceph_nfs_confh *)fid->raw); 174 } 175 176 /* 177 * get parent, if possible. 178 * 179 * FIXME: we could do better by querying the mds to discover the 180 * parent. 181 */ 182 static struct dentry *ceph_fh_to_parent(struct super_block *sb, 183 struct fid *fid, 184 int fh_len, int fh_type) 185 { 186 struct ceph_nfs_confh *cfh = (void *)fid->raw; 187 struct ceph_vino vino; 188 struct inode *inode; 189 struct dentry *dentry; 190 int err; 191 192 if (fh_type == 1) 193 return ERR_PTR(-ESTALE); 194 195 pr_debug("fh_to_parent %llx/%d\n", cfh->parent_ino, 196 cfh->parent_name_hash); 197 198 vino.ino = cfh->ino; 199 vino.snap = CEPH_NOSNAP; 200 inode = ceph_find_inode(sb, vino); 201 if (!inode) 202 return ERR_PTR(-ESTALE); 203 204 dentry = d_obtain_alias(inode); 205 if (!dentry) { 206 pr_err("fh_to_parent %llx -- inode %p but ENOMEM\n", 207 cfh->ino, inode); 208 iput(inode); 209 return ERR_PTR(-ENOMEM); 210 } 211 err = ceph_init_dentry(dentry); 212 if (err < 0) { 213 iput(inode); 214 return ERR_PTR(err); 215 } 216 dout("fh_to_parent %llx %p dentry %p\n", cfh->ino, inode, dentry); 217 return dentry; 218 } 219 220 const struct export_operations ceph_export_ops = { 221 .encode_fh = ceph_encode_fh, 222 .fh_to_dentry = ceph_fh_to_dentry, 223 .fh_to_parent = ceph_fh_to_parent, 224 }; 225