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  */
  41
  42 struct syncops_config_data {
  43         bool onclose;
  44 };
  45
  46 /*
  47   given a filename, find the parent directory
  48  */
  49 static char *parent_dir(TALLOC_CTX *mem_ctx, const char *name)
  50 {
  51         const char *p = strrchr(name, '/');
  52         if (p == NULL) {
  53                 return talloc_strdup(mem_ctx, ".");
  54         }
  55         return talloc_strndup(mem_ctx, name, (p+1) - name);
  56 }
  57
  58 /*
  59   fsync a directory by name
  60  */
  61 static void syncops_sync_directory(const char *dname)
  62 {
  63 #ifdef O_DIRECTORY
  64         int fd = open(dname, O_DIRECTORY|O_RDONLY);
  65         if (fd != -1) {
  66                 fsync(fd);
  67                 close(fd);
  68         }
  69 #else
  70         DIR *d = opendir(dname);
  71         if (d != NULL) {
  72                 fsync(dirfd(d));
  73                 closedir(d);
  74         }
  75 #endif
  76 }
  77
  78 /*
  79   sync two meta data changes for 2 names
  80  */
  81 static void syncops_two_names(const char *name1, const char *name2)
  82 {
  83         TALLOC_CTX *tmp_ctx = talloc_new(NULL);
  84         char *parent1, *parent2;
  85         parent1 = parent_dir(tmp_ctx, name1);
  86         parent2 = parent_dir(tmp_ctx, name2);
  87         if (!parent1 || !parent2) {
  88                 talloc_free(tmp_ctx);
  89                 return;
  90         }
  91         syncops_sync_directory(parent1);
  92         if (strcmp(parent1, parent2) != 0) {
  93                 syncops_sync_directory(parent2);
  94         }
  95         talloc_free(tmp_ctx);
  96 }
  97
  98 /*
  99   sync two meta data changes for 1 names
 100  */
 101 static void syncops_name(const char *name)
 102 {
 103         char *parent;
 104         parent = parent_dir(NULL, name);
 105         if (parent) {
 106                 syncops_sync_directory(parent);
 107                 talloc_free(parent);
 108         }
 109 }
 110
 111 /*
 112   sync two meta data changes for 1 names
 113  */
 114 static void syncops_smb_fname(const struct smb_filename *smb_fname)
 115 {
 116         char *parent;
 117         parent = parent_dir(NULL, smb_fname->base_name);
 118         if (parent) {
 119                 syncops_sync_directory(parent);
 120                 talloc_free(parent);
 121         }
 122 }
 123
 124
 125 /*
 126   rename needs special handling, as we may need to fsync two directories
 127  */
 128 static int syncops_rename(vfs_handle_struct *handle,
 129                           const struct smb_filename *smb_fname_src,
 130                           const struct smb_filename *smb_fname_dst)
 131 {
 132         int ret = SMB_VFS_NEXT_RENAME(handle, smb_fname_src, smb_fname_dst);
 133         if (ret == 0) {
 134                 syncops_two_names(smb_fname_src->base_name,
 135                                   smb_fname_dst->base_name);
 136         }
 137         return ret;
 138 }
 139
 140 /* handle the rest with a macro */
 141 #define SYNCOPS_NEXT(op, fname, args) do {   \
 142         int ret = SMB_VFS_NEXT_ ## op args; \
 143         if (ret == 0 && fname) syncops_name(fname); \
 144         return ret; \
 145 } while (0)
 146
 147 #define SYNCOPS_NEXT_SMB_FNAME(op, fname, args) do {   \
 148         int ret = SMB_VFS_NEXT_ ## op args; \
 149         if (ret == 0 && fname) syncops_smb_fname(fname); \
 150         return ret; \
 151 } while (0)
 152
 153 static int syncops_symlink(vfs_handle_struct *handle,
 154                            const char *oldname, const char *newname)
 155 {
 156         SYNCOPS_NEXT(SYMLINK, newname, (handle, oldname, newname));
 157 }
 158
 159 static int syncops_link(vfs_handle_struct *handle,
 160                          const char *oldname, const char *newname)
 161 {
 162         SYNCOPS_NEXT(LINK, newname, (handle, oldname, newname));
 163 }
 164
 165 static int syncops_open(vfs_handle_struct *handle,
 166                         struct smb_filename *smb_fname, files_struct *fsp,
 167                         int flags, mode_t mode)
 168 {
 169         SYNCOPS_NEXT_SMB_FNAME(OPEN, (flags&O_CREAT?smb_fname:NULL),
 170                                (handle, smb_fname, fsp, flags, mode));
 171 }
 172
 173 static int syncops_unlink(vfs_handle_struct *handle,
 174                           const struct smb_filename *smb_fname)
 175 {
 176         SYNCOPS_NEXT_SMB_FNAME(UNLINK, smb_fname, (handle, smb_fname));
 177 }
 178
 179 static int syncops_mknod(vfs_handle_struct *handle,
 180                          const char *fname, mode_t mode, SMB_DEV_T dev)
 181 {
 182         SYNCOPS_NEXT(MKNOD, fname, (handle, fname, mode, dev));
 183 }
 184
 185 static int syncops_mkdir(vfs_handle_struct *handle,  const char *fname, mode_t mode)
 186 {
 187         SYNCOPS_NEXT(MKDIR, fname, (handle, fname, mode));
 188 }
 189
 190 static int syncops_rmdir(vfs_handle_struct *handle,  const char *fname)
 191 {
 192         SYNCOPS_NEXT(RMDIR, fname, (handle, fname));
 193 }
 194
 195 /* close needs to be handled specially */
 196 static int syncops_close(vfs_handle_struct *handle, files_struct *fsp)
 197 {
 198         struct syncops_config_data *config;
 199
 200         SMB_VFS_HANDLE_GET_DATA(handle, config,
 201                                 struct syncops_config_data,
 202                                 return -1);
 203
 204         if (fsp->can_write && config->onclose) {
 205                 /* ideally we'd only do this if we have written some
 206                  data, but there is no flag for that in fsp yet. */
 207                 fsync(fsp->fh->fd);
 208         }
 209         return SMB_VFS_NEXT_CLOSE(handle, fsp);
 210 }
 211
 212 int syncops_connect(struct vfs_handle_struct *handle, const char *service,
 213                         const char *user)
 214 {
 215
 216         struct syncops_config_data *config;
 217         int ret = SMB_VFS_NEXT_CONNECT(handle, service, user);
 218         if (ret < 0) {
 219                 return ret;
 220         }
 221
 222         config = talloc_zero(handle->conn, struct syncops_config_data);
 223         if (!config) {
 224                 SMB_VFS_NEXT_DISCONNECT(handle);
 225                 DEBUG(0, ("talloc_zero() failed\n"));
 226                 return -1;
 227         }
 228
 229         config->onclose = lp_parm_bool(SNUM(handle->conn), "syncops",
 230                                         "onclose", true);
 231
 232         SMB_VFS_HANDLE_SET_DATA(handle, config,
 233                                 NULL, struct syncops_config_data,
 234                                 return -1);
 235
 236         return 0;
 237
 238 }
 239
 240 static struct vfs_fn_pointers vfs_syncops_fns = {
 241         .connect_fn = syncops_connect,
 242         .mkdir = syncops_mkdir,
 243         .rmdir = syncops_rmdir,
 244         .open = syncops_open,
 245         .rename = syncops_rename,
 246         .unlink = syncops_unlink,
 247         .symlink = syncops_symlink,
 248         .link = syncops_link,
 249         .mknod = syncops_mknod,
 250         .close_fn = syncops_close,
 251 };
 252
 253 NTSTATUS vfs_syncops_init(void)
 254 {
 255         NTSTATUS ret;
 256
 257         ret = smb_register_vfs(SMB_VFS_INTERFACE_VERSION, "syncops",
 258                                &vfs_syncops_fns);
 259
 260         if (!NT_STATUS_IS_OK(ret))
 261                 return ret;
 262
 263         return ret;
 264 }