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/*
* ensure meta data operations are performed synchronously
*
* Copyright (C) Andrew Tridgell 2007
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
#include "includes.h"
/*
Some filesystems (even some journaled filesystems) require that a
fsync() be performed on many meta data operations to ensure that the
operation is guaranteed to remain in the filesystem after a power
failure. This is particularly important for some cluster filesystems
which are participating in a node failover system with clustered
Samba
On those filesystems this module provides a way to perform those
operations safely.
most of the performance loss with this module is in fsync on close().
You can disable that with
syncops:onclose = no
that can be set either globally or per share.
*/
struct syncops_config_data {
bool onclose;
};
/*
given a filename, find the parent directory
*/
static char *parent_dir(TALLOC_CTX *mem_ctx, const char *name)
{
const char *p = strrchr(name, '/');
if (p == NULL) {
return talloc_strdup(mem_ctx, ".");
}
return talloc_strndup(mem_ctx, name, (p+1) - name);
}
/*
fsync a directory by name
*/
static void syncops_sync_directory(const char *dname)
{
#ifdef O_DIRECTORY
int fd = open(dname, O_DIRECTORY|O_RDONLY);
if (fd != -1) {
fsync(fd);
close(fd);
}
#else
DIR *d = opendir(dname);
if (d != NULL) {
fsync(dirfd(d));
closedir(d);
}
#endif
}
/*
sync two meta data changes for 2 names
*/
static void syncops_two_names(const char *name1, const char *name2)
{
TALLOC_CTX *tmp_ctx = talloc_new(NULL);
char *parent1, *parent2;
parent1 = parent_dir(tmp_ctx, name1);
parent2 = parent_dir(tmp_ctx, name2);
if (!parent1 || !parent2) {
talloc_free(tmp_ctx);
return;
}
syncops_sync_directory(parent1);
if (strcmp(parent1, parent2) != 0) {
syncops_sync_directory(parent2);
}
talloc_free(tmp_ctx);
}
/*
sync two meta data changes for 1 names
*/
static void syncops_name(const char *name)
{
char *parent;
parent = parent_dir(NULL, name);
if (parent) {
syncops_sync_directory(parent);
talloc_free(parent);
}
}
/*
sync two meta data changes for 1 names
*/
static void syncops_smb_fname(const struct smb_filename *smb_fname)
{
char *parent;
parent = parent_dir(NULL, smb_fname->base_name);
if (parent) {
syncops_sync_directory(parent);
talloc_free(parent);
}
}
/*
rename needs special handling, as we may need to fsync two directories
*/
static int syncops_rename(vfs_handle_struct *handle,
const struct smb_filename *smb_fname_src,
const struct smb_filename *smb_fname_dst)
{
int ret = SMB_VFS_NEXT_RENAME(handle, smb_fname_src, smb_fname_dst);
if (ret == 0) {
syncops_two_names(smb_fname_src->base_name,
smb_fname_dst->base_name);
}
return ret;
}
/* handle the rest with a macro */
#define SYNCOPS_NEXT(op, fname, args) do { \
int ret = SMB_VFS_NEXT_ ## op args; \
if (ret == 0 && fname) syncops_name(fname); \
return ret; \
} while (0)
#define SYNCOPS_NEXT_SMB_FNAME(op, fname, args) do { \
int ret = SMB_VFS_NEXT_ ## op args; \
if (ret == 0 && fname) syncops_smb_fname(fname); \
return ret; \
} while (0)
static int syncops_symlink(vfs_handle_struct *handle,
const char *oldname, const char *newname)
{
SYNCOPS_NEXT(SYMLINK, newname, (handle, oldname, newname));
}
static int syncops_link(vfs_handle_struct *handle,
const char *oldname, const char *newname)
{
SYNCOPS_NEXT(LINK, newname, (handle, oldname, newname));
}
static int syncops_open(vfs_handle_struct *handle,
struct smb_filename *smb_fname, files_struct *fsp,
int flags, mode_t mode)
{
SYNCOPS_NEXT_SMB_FNAME(OPEN, (flags&O_CREAT?smb_fname:NULL),
(handle, smb_fname, fsp, flags, mode));
}
static int syncops_unlink(vfs_handle_struct *handle,
const struct smb_filename *smb_fname)
{
SYNCOPS_NEXT_SMB_FNAME(UNLINK, smb_fname, (handle, smb_fname));
}
static int syncops_mknod(vfs_handle_struct *handle,
const char *fname, mode_t mode, SMB_DEV_T dev)
{
SYNCOPS_NEXT(MKNOD, fname, (handle, fname, mode, dev));
}
static int syncops_mkdir(vfs_handle_struct *handle, const char *fname, mode_t mode)
{
SYNCOPS_NEXT(MKDIR, fname, (handle, fname, mode));
}
static int syncops_rmdir(vfs_handle_struct *handle, const char *fname)
{
SYNCOPS_NEXT(RMDIR, fname, (handle, fname));
}
/* close needs to be handled specially */
static int syncops_close(vfs_handle_struct *handle, files_struct *fsp)
{
struct syncops_config_data *config;
SMB_VFS_HANDLE_GET_DATA(handle, config,
struct syncops_config_data,
return -1);
if (fsp->can_write && config->onclose) {
/* ideally we'd only do this if we have written some
data, but there is no flag for that in fsp yet. */
fsync(fsp->fh->fd);
}
return SMB_VFS_NEXT_CLOSE(handle, fsp);
}
int syncops_connect(struct vfs_handle_struct *handle, const char *service,
const char *user)
{
struct syncops_config_data *config;
int ret = SMB_VFS_NEXT_CONNECT(handle, service, user);
if (ret < 0) {
return ret;
}
config = talloc_zero(handle->conn, struct syncops_config_data);
if (!config) {
SMB_VFS_NEXT_DISCONNECT(handle);
DEBUG(0, ("talloc_zero() failed\n"));
return -1;
}
config->onclose = lp_parm_bool(SNUM(handle->conn), "syncops",
"onclose", true);
SMB_VFS_HANDLE_SET_DATA(handle, config,
NULL, struct syncops_config_data,
return -1);
return 0;
}
static struct vfs_fn_pointers vfs_syncops_fns = {
.connect_fn = syncops_connect,
.mkdir = syncops_mkdir,
.rmdir = syncops_rmdir,
.open = syncops_open,
.rename = syncops_rename,
.unlink = syncops_unlink,
.symlink = syncops_symlink,
.link = syncops_link,
.mknod = syncops_mknod,
.close_fn = syncops_close,
};
NTSTATUS vfs_syncops_init(void)
{
NTSTATUS ret;
ret = smb_register_vfs(SMB_VFS_INTERFACE_VERSION, "syncops",
&vfs_syncops_fns);
if (!NT_STATUS_IS_OK(ret))
return ret;
return ret;
}
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