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 int vfs_gluster_fuse_get_real_filename(struct vfs_handle_struct *handle,
  27                                               const char *path,
  28                                               const char *name,
  29                                               TALLOC_CTX *mem_ctx,
  30                                               char **_found_name)
  31 {
  32         int ret;
  33         char key_buf[GLUSTER_NAME_MAX + 64];
  34         char val_buf[GLUSTER_NAME_MAX + 1];
  35         char *found_name = NULL;
  36
  37         if (strlen(name) >= GLUSTER_NAME_MAX) {
  38                 errno = ENAMETOOLONG;
  39                 return -1;
  40         }
  41
  42         snprintf(key_buf, GLUSTER_NAME_MAX + 64,
  43                  "glusterfs.get_real_filename:%s", name);
  44
  45         ret = getxattr(path, key_buf, val_buf, GLUSTER_NAME_MAX + 1);
  46         if (ret == -1) {
  47                 if (errno == ENOATTR) {
  48                         errno = ENOENT;
  49                 }
  50                 return -1;
  51         }
  52
  53         found_name = talloc_strdup(mem_ctx, val_buf);
  54         if (found_name == NULL) {
  55                 errno = ENOMEM;
  56                 return -1;
  57         }
  58         *_found_name = found_name;
  59         return 0;
  60 }
  61
  62 struct device_mapping_entry {
  63         SMB_DEV_T device;       /* the local device, for reference */
  64         uint64_t mapped_device; /* the mapped device */
  65 };
  66
  67 struct vfs_glusterfs_fuse_handle_data {
  68         unsigned num_mapped_devices;
  69         struct device_mapping_entry *mapped_devices;
  70 };
  71
  72 /* a 64 bit hash, based on the one in tdb, copied from vfs_fileied */
  73 static uint64_t vfs_glusterfs_fuse_uint64_hash(const uint8_t *s, size_t len)
  74 {
  75         uint64_t value; /* Used to compute the hash value.  */
  76         uint32_t i;     /* Used to cycle through random values. */
  77
  78         /* Set the initial value from the key size. */
  79         for (value = 0x238F13AFLL * len, i=0; i < len; i++)
  80                 value = (value + (((uint64_t)s[i]) << (i*5 % 24)));
  81
  82         return (1103515243LL * value + 12345LL);
  83 }
  84
  85 static void vfs_glusterfs_fuse_load_devices(
  86                 struct vfs_glusterfs_fuse_handle_data *data)
  87 {
  88         FILE *f;
  89         struct mntent *m;
  90
  91         data->num_mapped_devices = 0;
  92         TALLOC_FREE(data->mapped_devices);
  93
  94         f = setmntent("/etc/mtab", "r");
  95         if (!f) {
  96                 return;
  97         }
  98
  99         while ((m = getmntent(f))) {
 100                 struct stat st;
 101                 char *p;
 102                 uint64_t mapped_device;
 103
 104                 if (stat(m->mnt_dir, &st) != 0) {
 105                         /* TODO: log? */
 106                         continue;
 107                 }
 108
 109                 /* strip the host part off of the fsname */
 110                 p = strrchr(m->mnt_fsname, ':');
 111                 if (p == NULL) {
 112                         p = m->mnt_fsname;
 113                 } else {
 114                         /* TODO: consider the case of '' ? */
 115                         p++;
 116                 }
 117
 118                 mapped_device = vfs_glusterfs_fuse_uint64_hash(
 119                                                 (const uint8_t *)p,
 120                                                 strlen(p));
 121
 122                 data->mapped_devices = talloc_realloc(data,
 123                                                 data->mapped_devices,
 124                                                 struct device_mapping_entry,
 125                                                 data->num_mapped_devices + 1);
 126                 if (data->mapped_devices == NULL) {
 127                         goto nomem;
 128                 }
 129
 130                 data->mapped_devices[data->num_mapped_devices].device =
 131                                                                 st.st_dev;
 132                 data->mapped_devices[data->num_mapped_devices].mapped_device =
 133                                                                 mapped_device;
 134
 135                 data->num_mapped_devices++;
 136         }
 137
 138         endmntent(f);
 139         return;
 140
 141 nomem:
 142         data->num_mapped_devices = 0;
 143         TALLOC_FREE(data->mapped_devices);
 144
 145         endmntent(f);
 146         return;
 147 }
 148
 149 static int vfs_glusterfs_fuse_map_device_cached(
 150                                 struct vfs_glusterfs_fuse_handle_data *data,
 151                                 SMB_DEV_T device,
 152                                 uint64_t *mapped_device)
 153 {
 154         unsigned i;
 155
 156         for (i = 0; i < data->num_mapped_devices; i++) {
 157                 if (data->mapped_devices[i].device == device) {
 158                         *mapped_device = data->mapped_devices[i].mapped_device;
 159                         return 0;
 160                 }
 161         }
 162
 163         return -1;
 164 }
 165
 166 static int vfs_glusterfs_fuse_map_device(
 167                                 struct vfs_glusterfs_fuse_handle_data *data,
 168                                 SMB_DEV_T device,
 169                                 uint64_t *mapped_device)
 170 {
 171         int ret;
 172
 173         ret = vfs_glusterfs_fuse_map_device_cached(data, device, mapped_device);
 174         if (ret == 0) {
 175                 return 0;
 176         }
 177
 178         vfs_glusterfs_fuse_load_devices(data);
 179
 180         ret = vfs_glusterfs_fuse_map_device_cached(data, device, mapped_device);
 181
 182         return ret;
 183 }
 184
 185 static struct file_id vfs_glusterfs_fuse_file_id_create(
 186                         struct vfs_handle_struct *handle,
 187                         const SMB_STRUCT_STAT *sbuf)
 188 {
 189         struct vfs_glusterfs_fuse_handle_data *data;
 190         struct file_id id;
 191         uint64_t mapped_device;
 192         int ret;
 193
 194         ZERO_STRUCT(id);
 195
 196         id = SMB_VFS_NEXT_FILE_ID_CREATE(handle, sbuf);
 197
 198         SMB_VFS_HANDLE_GET_DATA(handle, data,
 199                                 struct vfs_glusterfs_fuse_handle_data,
 200                                 return id);
 201
 202         ret = vfs_glusterfs_fuse_map_device(data, sbuf->st_ex_dev,
 203                                             &mapped_device);
 204         if (ret == 0) {
 205                 id.devid = mapped_device;
 206         } else {
 207                 DBG_WARNING("Failed to map device [%jx], falling back to "
 208                             "standard file_id [%jx]",
 209                             (uintmax_t)sbuf->st_ex_dev,
 210                             (uintmax_t)id.devid);
 211         }
 212
 213         DBG_DEBUG("Returning dev [%jx] inode [%jx]\n",
 214                   (uintmax_t)id.devid, (uintmax_t)id.inode);
 215
 216         return id;
 217 }
 218
 219 static int vfs_glusterfs_fuse_connect(struct vfs_handle_struct *handle,
 220                                       const char *service, const char *user)
 221 {
 222         struct vfs_glusterfs_fuse_handle_data *data;
 223         int ret = SMB_VFS_NEXT_CONNECT(handle, service, user);
 224
 225         if (ret < 0) {
 226                 return ret;
 227         }
 228
 229         data = talloc_zero(handle->conn, struct vfs_glusterfs_fuse_handle_data);
 230         if (data == NULL) {
 231                 DBG_ERR("talloc_zero() failed.\n");
 232                 SMB_VFS_NEXT_DISCONNECT(handle);
 233                 return -1;
 234         }
 235
 236         /*
 237          * Fill the cache in the tree connect, so that the first file/dir access
 238          * has chances of being fast...
 239          */
 240         vfs_glusterfs_fuse_load_devices(data);
 241
 242         SMB_VFS_HANDLE_SET_DATA(handle, data, NULL,
 243                                 struct vfs_glusterfs_fuse_handle_data,
 244                                 return -1);
 245
 246         DBG_DEBUG("vfs_glusterfs_fuse_connect(): connected to service[%s]\n",
 247                   service);
 248
 249         return 0;
 250 }
 251
 252 struct vfs_fn_pointers glusterfs_fuse_fns = {
 253
 254         .connect_fn = vfs_glusterfs_fuse_connect,
 255         .get_real_filename_fn = vfs_gluster_fuse_get_real_filename,
 256         .file_id_create_fn = vfs_glusterfs_fuse_file_id_create,
 257 };
 258
 259 static_decl_vfs;
 260 NTSTATUS vfs_glusterfs_fuse_init(TALLOC_CTX *ctx)
 261 {
 262         return smb_register_vfs(SMB_VFS_INTERFACE_VERSION,
 263                                 "glusterfs_fuse", &glusterfs_fuse_fns);
 264 }