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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
*/
static bool sync_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);
}
}
/*
rename needs special handling, as we may need to fsync two directories
*/
static int syncops_rename(vfs_handle_struct *handle,
const char *oldname, const char *newname)
{
int ret = SMB_VFS_NEXT_RENAME(handle, oldname, newname);
if (ret == 0) {
syncops_two_names(oldname, newname);
}
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)
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,
const char *fname, files_struct *fsp, int flags, mode_t mode)
{
SYNCOPS_NEXT(OPEN, (flags&O_CREAT?fname:NULL), (handle, fname, fsp, flags, mode));
}
static int syncops_unlink(vfs_handle_struct *handle, const char *fname)
{
SYNCOPS_NEXT(UNLINK, fname, (handle, 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)
{
if (fsp->can_write && sync_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);
}
/* VFS operations structure */
static vfs_op_tuple syncops_ops[] = {
/* directory operations */
{SMB_VFS_OP(syncops_mkdir), SMB_VFS_OP_MKDIR, SMB_VFS_LAYER_TRANSPARENT},
{SMB_VFS_OP(syncops_rmdir), SMB_VFS_OP_RMDIR, SMB_VFS_LAYER_TRANSPARENT},
/* File operations */
{SMB_VFS_OP(syncops_open), SMB_VFS_OP_OPEN, SMB_VFS_LAYER_TRANSPARENT},
{SMB_VFS_OP(syncops_rename), SMB_VFS_OP_RENAME, SMB_VFS_LAYER_TRANSPARENT},
{SMB_VFS_OP(syncops_unlink), SMB_VFS_OP_UNLINK, SMB_VFS_LAYER_TRANSPARENT},
{SMB_VFS_OP(syncops_symlink), SMB_VFS_OP_SYMLINK, SMB_VFS_LAYER_TRANSPARENT},
{SMB_VFS_OP(syncops_link), SMB_VFS_OP_LINK, SMB_VFS_LAYER_TRANSPARENT},
{SMB_VFS_OP(syncops_mknod), SMB_VFS_OP_MKNOD, SMB_VFS_LAYER_TRANSPARENT},
{SMB_VFS_OP(syncops_close), SMB_VFS_OP_CLOSE, SMB_VFS_LAYER_TRANSPARENT},
{SMB_VFS_OP(NULL), SMB_VFS_OP_NOOP, SMB_VFS_LAYER_NOOP}
};
NTSTATUS vfs_syncops_init(void)
{
NTSTATUS ret;
ret = smb_register_vfs(SMB_VFS_INTERFACE_VERSION, "syncops", syncops_ops);
if (!NT_STATUS_IS_OK(ret))
return ret;
sync_onclose = lp_parm_bool(-1, "syncops", "onclose", true);
return ret;
}
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