source3/modules/vfs_glusterfs_fuse.c

   1 /*
   2    Unix SMB/CIFS implementation.
   3
   4    Copyright (c) 2019 Guenther Deschner <gd@samba.org>
   5
   6    This program is free software; you can redistribute it and/or modify
   7    it under the terms of the GNU General Public License as published by
   8    the Free Software Foundation; either version 3 of the License, or
   9    (at your option) any later version.
  10
  11    This program is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14    GNU General Public License for more details.
  15
  16    You should have received a copy of the GNU General Public License
  17    along with this program.  If not, see <http://www.gnu.org/licenses/>.
  18 */
  19
  20 #include "includes.h"
  21 #include "smbd/smbd.h"
  22 #include "system/filesys.h"
  23
  24 #define GLUSTER_NAME_MAX 255
  25
  26 static NTSTATUS vfs_gluster_fuse_get_real_filename_at(
  27         struct vfs_handle_struct *handle,
  28         struct files_struct *dirfsp,
  29         const char *name,
  30         TALLOC_CTX *mem_ctx,
  31         char **_found_name)
  32 {
  33         int ret, dirfd;
  34         char key_buf[GLUSTER_NAME_MAX + 64];
  35         char val_buf[GLUSTER_NAME_MAX + 1];
  36         char *found_name = NULL;
  37
  38         if (strlen(name) >= GLUSTER_NAME_MAX) {
  39                 return NT_STATUS_OBJECT_NAME_INVALID;
  40         }
  41
  42         snprintf(key_buf, GLUSTER_NAME_MAX + 64,
  43                  "glusterfs.get_real_filename:%s", name);
  44
  45         dirfd = openat(fsp_get_pathref_fd(dirfsp), ".", O_RDONLY);
  46         if (dirfd == -1) {
  47                 NTSTATUS status = map_nt_error_from_unix(errno);
  48                 DBG_DEBUG("Could not open '.' in %s: %s\n",
  49                           fsp_str_dbg(dirfsp),
  50                           strerror(errno));
  51                 return status;
  52         }
  53
  54         ret = fgetxattr(dirfd, key_buf, val_buf, GLUSTER_NAME_MAX + 1);
  55         close(dirfd);
  56         if (ret == -1) {
  57                 if (errno == ENOATTR) {
  58                         errno = ENOENT;
  59                 }
  60                 return map_nt_error_from_unix(errno);
  61         }
  62
  63         found_name = talloc_strdup(mem_ctx, val_buf);
  64         if (found_name == NULL) {
  65                 return NT_STATUS_NO_MEMORY;
  66         }
  67         *_found_name = found_name;
  68         return NT_STATUS_OK;
  69 }
  70
  71 struct device_mapping_entry {
  72         SMB_DEV_T device;       /* the local device, for reference */
  73         uint64_t mapped_device; /* the mapped device */
  74 };
  75
  76 struct vfs_glusterfs_fuse_handle_data {
  77         unsigned num_mapped_devices;
  78         struct device_mapping_entry *mapped_devices;
  79 };
  80
  81 /* a 64 bit hash, based on the one in tdb, copied from vfs_fileied */
  82 static uint64_t vfs_glusterfs_fuse_uint64_hash(const uint8_t *s, size_t len)
  83 {
  84         uint64_t value; /* Used to compute the hash value.  */
  85         uint32_t i;     /* Used to cycle through random values. */
  86
  87         /* Set the initial value from the key size. */
  88         for (value = 0x238F13AFLL * len, i=0; i < len; i++)
  89                 value = (value + (((uint64_t)s[i]) << (i*5 % 24)));
  90
  91         return (1103515243LL * value + 12345LL);
  92 }
  93
  94 static void vfs_glusterfs_fuse_load_devices(
  95                 struct vfs_glusterfs_fuse_handle_data *data)
  96 {
  97         FILE *f;
  98         struct mntent *m;
  99
 100         data->num_mapped_devices = 0;
 101         TALLOC_FREE(data->mapped_devices);
 102
 103         f = setmntent("/etc/mtab", "r");
 104         if (!f) {
 105                 return;
 106         }
 107
 108         while ((m = getmntent(f))) {
 109                 struct stat st;
 110                 char *p;
 111                 uint64_t mapped_device;
 112
 113                 if (stat(m->mnt_dir, &st) != 0) {
 114                         /* TODO: log? */
 115                         continue;
 116                 }
 117
 118                 /* strip the host part off of the fsname */
 119                 p = strrchr(m->mnt_fsname, ':');
 120                 if (p == NULL) {
 121                         p = m->mnt_fsname;
 122                 } else {
 123                         /* TODO: consider the case of '' ? */
 124                         p++;
 125                 }
 126
 127                 mapped_device = vfs_glusterfs_fuse_uint64_hash(
 128                                                 (const uint8_t *)p,
 129                                                 strlen(p));
 130
 131                 data->mapped_devices = talloc_realloc(data,
 132                                                 data->mapped_devices,
 133                                                 struct device_mapping_entry,
 134                                                 data->num_mapped_devices + 1);
 135                 if (data->mapped_devices == NULL) {
 136                         goto nomem;
 137                 }
 138
 139                 data->mapped_devices[data->num_mapped_devices].device =
 140                                                                 st.st_dev;
 141                 data->mapped_devices[data->num_mapped_devices].mapped_device =
 142                                                                 mapped_device;
 143
 144                 data->num_mapped_devices++;
 145         }
 146
 147         endmntent(f);
 148         return;
 149
 150 nomem:
 151         data->num_mapped_devices = 0;
 152         TALLOC_FREE(data->mapped_devices);
 153
 154         endmntent(f);
 155         return;
 156 }
 157
 158 static int vfs_glusterfs_fuse_map_device_cached(
 159                                 struct vfs_glusterfs_fuse_handle_data *data,
 160                                 SMB_DEV_T device,
 161                                 uint64_t *mapped_device)
 162 {
 163         unsigned i;
 164
 165         for (i = 0; i < data->num_mapped_devices; i++) {
 166                 if (data->mapped_devices[i].device == device) {
 167                         *mapped_device = data->mapped_devices[i].mapped_device;
 168                         return 0;
 169                 }
 170         }
 171
 172         return -1;
 173 }
 174
 175 static int vfs_glusterfs_fuse_map_device(
 176                                 struct vfs_glusterfs_fuse_handle_data *data,
 177                                 SMB_DEV_T device,
 178                                 uint64_t *mapped_device)
 179 {
 180         int ret;
 181
 182         ret = vfs_glusterfs_fuse_map_device_cached(data, device, mapped_device);
 183         if (ret == 0) {
 184                 return 0;
 185         }
 186
 187         vfs_glusterfs_fuse_load_devices(data);
 188
 189         ret = vfs_glusterfs_fuse_map_device_cached(data, device, mapped_device);
 190
 191         return ret;
 192 }
 193
 194 static struct file_id vfs_glusterfs_fuse_file_id_create(
 195                         struct vfs_handle_struct *handle,
 196                         const SMB_STRUCT_STAT *sbuf)
 197 {
 198         struct vfs_glusterfs_fuse_handle_data *data;
 199         struct file_id id;
 200         uint64_t mapped_device;
 201         int ret;
 202
 203         ZERO_STRUCT(id);
 204
 205         id = SMB_VFS_NEXT_FILE_ID_CREATE(handle, sbuf);
 206
 207         SMB_VFS_HANDLE_GET_DATA(handle, data,
 208                                 struct vfs_glusterfs_fuse_handle_data,
 209                                 return id);
 210
 211         ret = vfs_glusterfs_fuse_map_device(data, sbuf->st_ex_dev,
 212                                             &mapped_device);
 213         if (ret == 0) {
 214                 id.devid = mapped_device;
 215         } else {
 216                 DBG_WARNING("Failed to map device [%jx], falling back to "
 217                             "standard file_id [%jx]\n",
 218                             (uintmax_t)sbuf->st_ex_dev,
 219                             (uintmax_t)id.devid);
 220         }
 221
 222         DBG_DEBUG("Returning dev [%jx] inode [%jx]\n",
 223                   (uintmax_t)id.devid, (uintmax_t)id.inode);
 224
 225         return id;
 226 }
 227
 228 static int vfs_glusterfs_fuse_connect(struct vfs_handle_struct *handle,
 229                                       const char *service, const char *user)
 230 {
 231         struct vfs_glusterfs_fuse_handle_data *data;
 232         int ret = SMB_VFS_NEXT_CONNECT(handle, service, user);
 233
 234         if (ret < 0) {
 235                 return ret;
 236         }
 237
 238         data = talloc_zero(handle->conn, struct vfs_glusterfs_fuse_handle_data);
 239         if (data == NULL) {
 240                 DBG_ERR("talloc_zero() failed.\n");
 241                 SMB_VFS_NEXT_DISCONNECT(handle);
 242                 return -1;
 243         }
 244
 245         /*
 246          * Fill the cache in the tree connect, so that the first file/dir access
 247          * has chances of being fast...
 248          */
 249         vfs_glusterfs_fuse_load_devices(data);
 250
 251         SMB_VFS_HANDLE_SET_DATA(handle, data, NULL,
 252                                 struct vfs_glusterfs_fuse_handle_data,
 253                                 return -1);
 254
 255         DBG_DEBUG("vfs_glusterfs_fuse_connect(): connected to service[%s]\n",
 256                   service);
 257
 258         return 0;
 259 }
 260
 261 struct vfs_fn_pointers glusterfs_fuse_fns = {
 262
 263         .connect_fn = vfs_glusterfs_fuse_connect,
 264         .get_real_filename_at_fn = vfs_gluster_fuse_get_real_filename_at,
 265         .file_id_create_fn = vfs_glusterfs_fuse_file_id_create,
 266 };
 267
 268 static_decl_vfs;
 269 NTSTATUS vfs_glusterfs_fuse_init(TALLOC_CTX *ctx)
 270 {
 271         return smb_register_vfs(SMB_VFS_INTERFACE_VERSION,
 272                                 "glusterfs_fuse", &glusterfs_fuse_fns);
 273 }