summaryrefslogtreecommitdiff
path: root/source3/modules/vfs_syncops.c
blob: 562195cbda7abf39003e7c89505cba85d666c097 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
/* 
 * 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);
	}
}

/*
  sync two meta data changes for 1 names
 */
static void syncops_smb_fname(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 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)

#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 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;
}