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
  36 /*
  37   most of the performance loss with this module is in fsync on close().
  38   You can disable that with syncops:onclose = no
  39  */
  40 static bool sync_onclose;
  41
  42 /*
  43   given a filename, find the parent directory
  44  */
  45 static char *parent_dir(TALLOC_CTX *mem_ctx, const char *name)
  46 {
  47         const char *p = strrchr(name, '/');
  48         if (p == NULL) {
  49                 return talloc_strdup(mem_ctx, ".");
  50         }
  51         return talloc_strndup(mem_ctx, name, (p+1) - name);
  52 }
  53
  54 /*
  55   fsync a directory by name
  56  */
  57 static void syncops_sync_directory(const char *dname)
  58 {
  59 #ifdef O_DIRECTORY
  60         int fd = open(dname, O_DIRECTORY|O_RDONLY);
  61         if (fd != -1) {
  62                 fsync(fd);
  63                 close(fd);
  64         }
  65 #else
  66         DIR *d = opendir(dname);
  67         if (d != NULL) {
  68                 fsync(dirfd(d));
  69                 closedir(d);
  70         }
  71 #endif
  72 }
  73
  74 /*
  75   sync two meta data changes for 2 names
  76  */
  77 static void syncops_two_names(const char *name1, const char *name2)
  78 {
  79         TALLOC_CTX *tmp_ctx = talloc_new(NULL);
  80         char *parent1, *parent2;
  81         parent1 = parent_dir(tmp_ctx, name1);
  82         parent2 = parent_dir(tmp_ctx, name2);
  83         if (!parent1 || !parent2) {
  84                 talloc_free(tmp_ctx);
  85                 return;
  86         }
  87         syncops_sync_directory(parent1);
  88         if (strcmp(parent1, parent2) != 0) {
  89                 syncops_sync_directory(parent2);
  90         }
  91         talloc_free(tmp_ctx);
  92 }
  93
  94 /*
  95   sync two meta data changes for 1 names
  96  */
  97 static void syncops_name(const char *name)
  98 {
  99         char *parent;
 100         parent = parent_dir(NULL, name);
 101         if (parent) {
 102                 syncops_sync_directory(parent);
 103                 talloc_free(parent);
 104         }
 105 }
 106
 107 /*
 108   sync two meta data changes for 1 names
 109  */
 110 static void syncops_smb_fname(const struct smb_filename *smb_fname)
 111 {
 112         char *parent;
 113         parent = parent_dir(NULL, smb_fname->base_name);
 114         if (parent) {
 115                 syncops_sync_directory(parent);
 116                 talloc_free(parent);
 117         }
 118 }
 119
 120
 121 /*
 122   rename needs special handling, as we may need to fsync two directories
 123  */
 124 static int syncops_rename(vfs_handle_struct *handle,
 125                           const struct smb_filename *smb_fname_src,
 126                           const struct smb_filename *smb_fname_dst)
 127 {
 128         int ret = SMB_VFS_NEXT_RENAME(handle, smb_fname_src, smb_fname_dst);
 129         if (ret == 0) {
 130                 syncops_two_names(smb_fname_src->base_name,
 131                                   smb_fname_dst->base_name);
 132         }
 133         return ret;
 134 }
 135
 136 /* handle the rest with a macro */
 137 #define SYNCOPS_NEXT(op, fname, args) do {   \
 138         int ret = SMB_VFS_NEXT_ ## op args; \
 139         if (ret == 0 && fname) syncops_name(fname); \
 140         return ret; \
 141 } while (0)
 142
 143 #define SYNCOPS_NEXT_SMB_FNAME(op, fname, args) do {   \
 144         int ret = SMB_VFS_NEXT_ ## op args; \
 145         if (ret == 0 && fname) syncops_smb_fname(fname); \
 146         return ret; \
 147 } while (0)
 148
 149 static int syncops_symlink(vfs_handle_struct *handle,
 150                            const char *oldname, const char *newname)
 151 {
 152         SYNCOPS_NEXT(SYMLINK, newname, (handle, oldname, newname));
 153 }
 154
 155 static int syncops_link(vfs_handle_struct *handle,
 156                          const char *oldname, const char *newname)
 157 {
 158         SYNCOPS_NEXT(LINK, newname, (handle, oldname, newname));
 159 }
 160
 161 static int syncops_open(vfs_handle_struct *handle,
 162                         struct smb_filename *smb_fname, files_struct *fsp,
 163                         int flags, mode_t mode)
 164 {
 165         SYNCOPS_NEXT_SMB_FNAME(OPEN, (flags&O_CREAT?smb_fname:NULL),
 166                                (handle, smb_fname, fsp, flags, mode));
 167 }
 168
 169 static int syncops_unlink(vfs_handle_struct *handle,
 170                           const struct smb_filename *smb_fname)
 171 {
 172         SYNCOPS_NEXT_SMB_FNAME(UNLINK, smb_fname, (handle, smb_fname));
 173 }
 174
 175 static int syncops_mknod(vfs_handle_struct *handle,
 176                          const char *fname, mode_t mode, SMB_DEV_T dev)
 177 {
 178         SYNCOPS_NEXT(MKNOD, fname, (handle, fname, mode, dev));
 179 }
 180
 181 static int syncops_mkdir(vfs_handle_struct *handle,  const char *fname, mode_t mode)
 182 {
 183         SYNCOPS_NEXT(MKDIR, fname, (handle, fname, mode));
 184 }
 185
 186 static int syncops_rmdir(vfs_handle_struct *handle,  const char *fname)
 187 {
 188         SYNCOPS_NEXT(RMDIR, fname, (handle, fname));
 189 }
 190
 191 /* close needs to be handled specially */
 192 static int syncops_close(vfs_handle_struct *handle, files_struct *fsp)
 193 {
 194         if (fsp->can_write && sync_onclose) {
 195                 /* ideally we'd only do this if we have written some
 196                  data, but there is no flag for that in fsp yet. */
 197                 fsync(fsp->fh->fd);
 198         }
 199         return SMB_VFS_NEXT_CLOSE(handle, fsp);
 200 }
 201
 202
 203 static struct vfs_fn_pointers vfs_syncops_fns = {
 204         .mkdir = syncops_mkdir,
 205         .rmdir = syncops_rmdir,
 206         .open = syncops_open,
 207         .rename = syncops_rename,
 208         .unlink = syncops_unlink,
 209         .symlink = syncops_symlink,
 210         .link = syncops_link,
 211         .mknod = syncops_mknod,
 212         .close_fn = syncops_close,
 213 };
 214
 215 NTSTATUS vfs_syncops_init(void)
 216 {
 217         NTSTATUS ret;
 218
 219         ret = smb_register_vfs(SMB_VFS_INTERFACE_VERSION, "syncops",
 220                                &vfs_syncops_fns);
 221
 222         if (!NT_STATUS_IS_OK(ret))
 223                 return ret;
 224
 225         sync_onclose = lp_parm_bool(-1, "syncops", "onclose", true);
 226
 227         return ret;
 228 }