2 * Copyright (c) James Peach 2006, 2007
3 * Copyright (c) David Losada Carballo 2007
5 * This program is free software; you can redistribute it and/or modify
6 * it under the terms of the GNU General Public License as published by
7 * the Free Software Foundation; either version 3 of the License, or
8 * (at your option) any later version.
10 * This program is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 * GNU General Public License for more details.
15 * You should have received a copy of the GNU General Public License
16 * along with this program; if not, see <http://www.gnu.org/licenses/>.
21 /* Commit data module.
23 * The purpose of this module is to flush data to disk at regular intervals,
24 * just like the NFS commit operation. There's two rationales for this. First,
25 * it minimises the data loss in case of a power outage without incurring
26 * the poor performance of synchronous I/O. Second, a steady flush rate
27 * can produce better throughput than suddenly dumping massive amounts of
32 * commit: dthresh Amount of dirty data that can accumulate
33 * before we commit (sync) it.
35 * commit: debug Debug level at which to emit messages.
37 * commit: eof mode String. Tunes how the module tries to guess when
38 * the client has written the last bytes of the file.
39 * Possible values (default = hinted):
41 * (*) = hinted Some clients (i.e. Windows Explorer) declare the
42 * size of the file before transferring it. With this
43 * option, we remember that hint, and commit after
44 * writing in that file position. If the client
45 * doesn't declare the size of file, commiting on EOF
48 * = growth Commits after a write operation has made the file
49 * size grow. If the client declares a file size, it
50 * refrains to commit until the file has reached it.
51 * Useful for defeating writeback on NFS shares.
55 #define MODULE "commit"
57 static int module_debug;
68 /* For chunk-based commits */
69 SMB_OFF_T dbytes; /* Dirty (uncommitted) bytes */
70 SMB_OFF_T dthresh; /* Dirty data threshold */
71 /* For commits on EOF */
73 SMB_OFF_T eof; /* Expected file size */
77 struct commit_info * c,
83 ("%s: flushing %lu dirty bytes\n",
84 MODULE, (unsigned long)c->dbytes));
87 result = fdatasync(fd);
94 c->dbytes = 0; /* on success, no dirty bytes */
99 static int commit_all(
100 struct vfs_handle_struct * handle,
103 struct commit_info *c;
105 if ((c = VFS_FETCH_FSP_EXTENSION(handle, fsp))) {
108 ("%s: flushing %lu dirty bytes\n",
109 MODULE, (unsigned long)c->dbytes));
111 return commit_do(c, fsp->fh->fd);
118 struct vfs_handle_struct * handle,
123 struct commit_info *c;
125 if ((c = VFS_FETCH_FSP_EXTENSION(handle, fsp)) == NULL) {
129 c->dbytes += last_write; /* dirty bytes always counted */
131 if (c->dthresh && (c->dbytes > c->dthresh)) {
132 return commit_do(c, fsp->fh->fd);
135 /* Return if we are not in EOF mode or if we have temporarily opted
138 if (c->on_eof == EOF_NONE || c->eof < 0) {
142 /* This write hit or went past our cache the file size. */
143 if ((offset + last_write) >= c->eof) {
144 if (commit_do(c, fsp->fh->fd) == -1) {
148 /* Hinted mode only commits the first time we hit EOF. */
149 if (c->on_eof == EOF_HINTED) {
151 } else if (c->on_eof == EOF_GROWTH) {
152 c->eof = offset + last_write;
159 static int commit_connect(
160 struct vfs_handle_struct * handle,
161 const char * service,
164 module_debug = lp_parm_int(SNUM(handle->conn), MODULE, "debug", 100);
165 return SMB_VFS_NEXT_CONNECT(handle, service, user);
168 static int commit_open(
169 vfs_handle_struct * handle,
176 const char *eof_mode;
177 struct commit_info *c = NULL;
180 /* Don't bother with read-only files. */
181 if ((flags & O_ACCMODE) == O_RDONLY) {
182 return SMB_VFS_NEXT_OPEN(handle, fname, fsp, flags, mode);
185 /* Read and check module configuration */
186 dthresh = conv_str_size(lp_parm_const_string(SNUM(handle->conn),
187 MODULE, "dthresh", NULL));
189 eof_mode = lp_parm_const_string(SNUM(handle->conn),
190 MODULE, "eof mode", "none");
192 if (dthresh > 0 || !strequal(eof_mode, "none")) {
193 c = VFS_ADD_FSP_EXTENSION(handle, fsp, struct commit_info);
194 /* Process main tunables */
196 c->dthresh = dthresh;
198 c->on_eof = EOF_NONE;
202 /* Process eof_mode tunable */
204 if (strequal(eof_mode, "hinted")) {
205 c->on_eof = EOF_HINTED;
206 } else if (strequal(eof_mode, "growth")) {
207 c->on_eof = EOF_GROWTH;
211 fd = SMB_VFS_NEXT_OPEN(handle, fname, fsp, flags, mode);
213 VFS_REMOVE_FSP_EXTENSION(handle, fsp);
217 /* EOF commit modes require us to know the initial file size. */
218 if (c && (c->on_eof != EOF_NONE)) {
220 if (SMB_VFS_FSTAT(fsp, &st) == -1) {
229 static ssize_t commit_write(
230 vfs_handle_struct * handle,
237 ret = SMB_VFS_NEXT_WRITE(handle, fsp, fd, data, count);
240 if (commit(handle, fsp, fsp->fh->pos, ret) == -1) {
248 static ssize_t commit_pwrite(
249 vfs_handle_struct * handle,
257 ret = SMB_VFS_NEXT_PWRITE(handle, fsp, data, count, offset);
259 if (commit(handle, fsp, offset, ret) == -1) {
267 static int commit_close(
268 vfs_handle_struct * handle,
272 /* Commit errors not checked, close() will find them again */
273 commit_all(handle, fsp);
274 return SMB_VFS_NEXT_CLOSE(handle, fsp, fd);
277 static int commit_ftruncate(
278 vfs_handle_struct * handle,
285 result = SMB_VFS_NEXT_FTRUNCATE(handle, fsp, fd, len);
287 struct commit_info *c;
288 if ((c = VFS_FETCH_FSP_EXTENSION(handle, fsp))) {
289 commit(handle, fsp, len, 0);
297 static vfs_op_tuple commit_ops [] =
299 {SMB_VFS_OP(commit_open),
300 SMB_VFS_OP_OPEN, SMB_VFS_LAYER_TRANSPARENT},
301 {SMB_VFS_OP(commit_close),
302 SMB_VFS_OP_CLOSE, SMB_VFS_LAYER_TRANSPARENT},
303 {SMB_VFS_OP(commit_write),
304 SMB_VFS_OP_WRITE, SMB_VFS_LAYER_TRANSPARENT},
305 {SMB_VFS_OP(commit_pwrite),
306 SMB_VFS_OP_PWRITE, SMB_VFS_LAYER_TRANSPARENT},
307 {SMB_VFS_OP(commit_connect),
308 SMB_VFS_OP_CONNECT, SMB_VFS_LAYER_TRANSPARENT},
309 {SMB_VFS_OP(commit_ftruncate),
310 SMB_VFS_OP_FTRUNCATE, SMB_VFS_LAYER_TRANSPARENT},
312 {SMB_VFS_OP(NULL), SMB_VFS_OP_NOOP, SMB_VFS_LAYER_NOOP}
315 NTSTATUS vfs_commit_init(void);
316 NTSTATUS vfs_commit_init(void)
318 return smb_register_vfs(SMB_VFS_INTERFACE_VERSION, MODULE, commit_ops);