source3/modules/vfs_syncops.c

   1 /*
   2  * ensure meta data operations are performed synchronously
   3  *
   4  * Copyright (C) Andrew Tridgell     2007
   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 2 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, write to the Free Software
  18  * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  19  */
  20
  21 #include "includes.h"
  22
  23 /*
  24
  25   Some filesystems (even some journaled filesystems) require that a
  26   fsync() be performed on many meta data operations to ensure that the
  27   operation is guaranteed to remain in the filesystem after a power
  28   failure. This is particularly important for some cluster filesystems
  29   which are participating in a node failover system with clustered
  30   Samba
  31
  32   On those filesystems this module provides a way to perform those
  33   operations safely.
  34
  35   most of the performance loss with this module is in fsync on close().
  36   You can disable that with
  37      syncops:onclose = no
  38   that can be set either globally or per share.
  39
  40   you can also disable the module completely for a service with
  41      syncops:disable = true
  42
  43  */
  44
  45 struct syncops_config_data {
  46         bool onclose;
  47         bool disable;
  48 };
  49
  50 /*
  51   given a filename, find the parent directory
  52  */
  53 static char *parent_dir(TALLOC_CTX *mem_ctx, const char *name)
  54 {
  55         const char *p = strrchr(name, '/');
  56         if (p == NULL) {
  57                 return talloc_strdup(mem_ctx, ".");
  58         }
  59         return talloc_strndup(mem_ctx, name, (p+1) - name);
  60 }
  61
  62 /*
  63   fsync a directory by name
  64  */
  65 static void syncops_sync_directory(const char *dname)
  66 {
  67 #ifdef O_DIRECTORY
  68         int fd = open(dname, O_DIRECTORY|O_RDONLY);
  69         if (fd != -1) {
  70                 fsync(fd);
  71                 close(fd);
  72         }
  73 #else
  74         DIR *d = opendir(dname);
  75         if (d != NULL) {
  76                 fsync(dirfd(d));
  77                 closedir(d);
  78         }
  79 #endif
  80 }
  81
  82 /*
  83   sync two meta data changes for 2 names
  84  */
  85 static void syncops_two_names(const char *name1, const char *name2)
  86 {
  87         TALLOC_CTX *tmp_ctx = talloc_new(NULL);
  88         char *parent1, *parent2;
  89         parent1 = parent_dir(tmp_ctx, name1);
  90         parent2 = parent_dir(tmp_ctx, name2);
  91         if (!parent1 || !parent2) {
  92                 talloc_free(tmp_ctx);
  93                 return;
  94         }
  95         syncops_sync_directory(parent1);
  96         if (strcmp(parent1, parent2) != 0) {
  97                 syncops_sync_directory(parent2);
  98         }
  99         talloc_free(tmp_ctx);
 100 }
 101
 102 /*
 103   sync two meta data changes for 1 names
 104  */
 105 static void syncops_name(const char *name)
 106 {
 107         char *parent;
 108         parent = parent_dir(NULL, name);
 109         if (parent) {
 110                 syncops_sync_directory(parent);
 111                 talloc_free(parent);
 112         }
 113 }
 114
 115 /*
 116   sync two meta data changes for 1 names
 117  */
 118 static void syncops_smb_fname(const struct smb_filename *smb_fname)
 119 {
 120         char *parent;
 121         parent = parent_dir(NULL, smb_fname->base_name);
 122         if (parent) {
 123                 syncops_sync_directory(parent);
 124                 talloc_free(parent);
 125         }
 126 }
 127
 128
 129 /*
 130   rename needs special handling, as we may need to fsync two directories
 131  */
 132 static int syncops_rename(vfs_handle_struct *handle,
 133                           const struct smb_filename *smb_fname_src,
 134                           const struct smb_filename *smb_fname_dst)
 135 {
 136
 137         int ret;
 138         struct syncops_config_data *config;
 139
 140         SMB_VFS_HANDLE_GET_DATA(handle, config,
 141                                 struct syncops_config_data,
 142                                 return -1);
 143
 144         ret = SMB_VFS_NEXT_RENAME(handle, smb_fname_src, smb_fname_dst);
 145         if (ret == 0 && !config->disable) {
 146                 syncops_two_names(smb_fname_src->base_name,
 147                                   smb_fname_dst->base_name);
 148         }
 149         return ret;
 150 }
 151
 152 /* handle the rest with a macro */
 153 #define SYNCOPS_NEXT(op, fname, args) do {   \
 154         int ret; \
 155         struct syncops_config_data *config; \
 156         SMB_VFS_HANDLE_GET_DATA(handle, config, \
 157                                 struct syncops_config_data, \
 158                                 return -1); \
 159         ret = SMB_VFS_NEXT_ ## op args; \
 160         if (ret == 0 \
 161                 && !config->disable \
 162                 && fname) syncops_name(fname); \
 163         return ret; \
 164 } while (0)
 165
 166 #define SYNCOPS_NEXT_SMB_FNAME(op, fname, args) do {   \
 167         int ret; \
 168         struct syncops_config_data *config; \
 169         SMB_VFS_HANDLE_GET_DATA(handle, config, \
 170                                 struct syncops_config_data, \
 171                                 return -1); \
 172         ret = SMB_VFS_NEXT_ ## op args; \
 173         if (ret == 0 \
 174         && !config->disable \
 175         && fname) syncops_smb_fname(fname); \
 176         return ret; \
 177 } while (0)
 178
 179 static int syncops_symlink(vfs_handle_struct *handle,
 180                            const char *oldname, const char *newname)
 181 {
 182         SYNCOPS_NEXT(SYMLINK, newname, (handle, oldname, newname));
 183 }
 184
 185 static int syncops_link(vfs_handle_struct *handle,
 186                          const char *oldname, const char *newname)
 187 {
 188         SYNCOPS_NEXT(LINK, newname, (handle, oldname, newname));
 189 }
 190
 191 static int syncops_open(vfs_handle_struct *handle,
 192                         struct smb_filename *smb_fname, files_struct *fsp,
 193                         int flags, mode_t mode)
 194 {
 195         SYNCOPS_NEXT_SMB_FNAME(OPEN, (flags&O_CREAT?smb_fname:NULL),
 196                                (handle, smb_fname, fsp, flags, mode));
 197 }
 198
 199 static int syncops_unlink(vfs_handle_struct *handle,
 200                           const struct smb_filename *smb_fname)
 201 {
 202         SYNCOPS_NEXT_SMB_FNAME(UNLINK, smb_fname, (handle, smb_fname));
 203 }
 204
 205 static int syncops_mknod(vfs_handle_struct *handle,
 206                          const char *fname, mode_t mode, SMB_DEV_T dev)
 207 {
 208         SYNCOPS_NEXT(MKNOD, fname, (handle, fname, mode, dev));
 209 }
 210
 211 static int syncops_mkdir(vfs_handle_struct *handle,  const char *fname, mode_t mode)
 212 {
 213         SYNCOPS_NEXT(MKDIR, fname, (handle, fname, mode));
 214 }
 215
 216 static int syncops_rmdir(vfs_handle_struct *handle,  const char *fname)
 217 {
 218         SYNCOPS_NEXT(RMDIR, fname, (handle, fname));
 219 }
 220
 221 /* close needs to be handled specially */
 222 static int syncops_close(vfs_handle_struct *handle, files_struct *fsp)
 223 {
 224         struct syncops_config_data *config;
 225
 226         SMB_VFS_HANDLE_GET_DATA(handle, config,
 227                                 struct syncops_config_data,
 228                                 return -1);
 229
 230         if (fsp->can_write && config->onclose) {
 231                 /* ideally we'd only do this if we have written some
 232                  data, but there is no flag for that in fsp yet. */
 233                 fsync(fsp->fh->fd);
 234         }
 235         return SMB_VFS_NEXT_CLOSE(handle, fsp);
 236 }
 237
 238 int syncops_connect(struct vfs_handle_struct *handle, const char *service,
 239                         const char *user)
 240 {
 241
 242         struct syncops_config_data *config;
 243         int ret = SMB_VFS_NEXT_CONNECT(handle, service, user);
 244         if (ret < 0) {
 245                 return ret;
 246         }
 247
 248         config = talloc_zero(handle->conn, struct syncops_config_data);
 249         if (!config) {
 250                 SMB_VFS_NEXT_DISCONNECT(handle);
 251                 DEBUG(0, ("talloc_zero() failed\n"));
 252                 return -1;
 253         }
 254
 255         config->onclose = lp_parm_bool(SNUM(handle->conn), "syncops",
 256                                         "onclose", true);
 257
 258         config->disable = lp_parm_bool(SNUM(handle->conn), "syncops",
 259                                         "disable", false);
 260
 261         SMB_VFS_HANDLE_SET_DATA(handle, config,
 262                                 NULL, struct syncops_config_data,
 263                                 return -1);
 264
 265         return 0;
 266
 267 }
 268
 269 static struct vfs_fn_pointers vfs_syncops_fns = {
 270         .connect_fn = syncops_connect,
 271         .mkdir = syncops_mkdir,
 272         .rmdir = syncops_rmdir,
 273         .open = syncops_open,
 274         .rename = syncops_rename,
 275         .unlink = syncops_unlink,
 276         .symlink = syncops_symlink,
 277         .link = syncops_link,
 278         .mknod = syncops_mknod,
 279         .close_fn = syncops_close,
 280 };
 281
 282 NTSTATUS vfs_syncops_init(void)
 283 {
 284         NTSTATUS ret;
 285
 286         ret = smb_register_vfs(SMB_VFS_INTERFACE_VERSION, "syncops",
 287                                &vfs_syncops_fns);
 288
 289         if (!NT_STATUS_IS_OK(ret))
 290                 return ret;
 291
 292         return ret;
 293 }