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/>.
20 #include "smbd/smbd.h"
22 /* Commit data module.
24 * The purpose of this module is to flush data to disk at regular intervals,
25 * just like the NFS commit operation. There's two rationales for this. First,
26 * it minimises the data loss in case of a power outage without incurring
27 * the poor performance of synchronous I/O. Second, a steady flush rate
28 * can produce better throughput than suddenly dumping massive amounts of
33 * commit: dthresh Amount of dirty data that can accumulate
34 * before we commit (sync) it.
36 * commit: debug Debug level at which to emit messages.
38 * commit: eof mode String. Tunes how the module tries to guess when
39 * the client has written the last bytes of the file.
40 * Possible values (default = hinted):
42 * (*) = hinted Some clients (i.e. Windows Explorer) declare the
43 * size of the file before transferring it. With this
44 * option, we remember that hint, and commit after
45 * writing in that file position. If the client
46 * doesn't declare the size of file, commiting on EOF
49 * = growth Commits after a write operation has made the file
50 * size grow. If the client declares a file size, it
51 * refrains to commit until the file has reached it.
52 * Useful for defeating writeback on NFS shares.
56 #define MODULE "commit"
58 static int module_debug;
69 /* For chunk-based commits */
70 SMB_OFF_T dbytes; /* Dirty (uncommitted) bytes */
71 SMB_OFF_T dthresh; /* Dirty data threshold */
72 /* For commits on EOF */
74 SMB_OFF_T eof; /* Expected file size */
78 struct commit_info * c,
84 ("%s: flushing %lu dirty bytes\n",
85 MODULE, (unsigned long)c->dbytes));
88 result = fdatasync(fd);
92 DEBUG(0, ("%s: WARNING: no commit support on this platform\n",
97 c->dbytes = 0; /* on success, no dirty bytes */
102 static int commit_all(
103 struct vfs_handle_struct * handle,
106 struct commit_info *c;
108 if ((c = (struct commit_info *)VFS_FETCH_FSP_EXTENSION(handle, fsp))) {
111 ("%s: flushing %lu dirty bytes\n",
112 MODULE, (unsigned long)c->dbytes));
114 return commit_do(c, fsp->fh->fd);
121 struct vfs_handle_struct * handle,
126 struct commit_info *c;
128 if ((c = (struct commit_info *)VFS_FETCH_FSP_EXTENSION(handle, fsp))
133 c->dbytes += last_write; /* dirty bytes always counted */
135 if (c->dthresh && (c->dbytes > c->dthresh)) {
136 return commit_do(c, fsp->fh->fd);
139 /* Return if we are not in EOF mode or if we have temporarily opted
142 if (c->on_eof == EOF_NONE || c->eof < 0) {
146 /* This write hit or went past our cache the file size. */
147 if ((offset + last_write) >= c->eof) {
148 if (commit_do(c, fsp->fh->fd) == -1) {
152 /* Hinted mode only commits the first time we hit EOF. */
153 if (c->on_eof == EOF_HINTED) {
155 } else if (c->on_eof == EOF_GROWTH) {
156 c->eof = offset + last_write;
163 static int commit_connect(
164 struct vfs_handle_struct * handle,
165 const char * service,
168 int ret = SMB_VFS_NEXT_CONNECT(handle, service, user);
174 module_debug = lp_parm_int(SNUM(handle->conn), MODULE, "debug", 100);
178 static int commit_open(
179 vfs_handle_struct * handle,
180 struct smb_filename *smb_fname,
186 const char *eof_mode;
187 struct commit_info *c = NULL;
190 /* Don't bother with read-only files. */
191 if ((flags & O_ACCMODE) == O_RDONLY) {
192 return SMB_VFS_NEXT_OPEN(handle, smb_fname, fsp, flags, mode);
195 /* Read and check module configuration */
196 dthresh = conv_str_size(lp_parm_const_string(SNUM(handle->conn),
197 MODULE, "dthresh", NULL));
199 eof_mode = lp_parm_const_string(SNUM(handle->conn),
200 MODULE, "eof mode", "none");
202 if (dthresh > 0 || !strequal(eof_mode, "none")) {
203 c = (struct commit_info *)VFS_ADD_FSP_EXTENSION(
204 handle, fsp, struct commit_info, NULL);
205 /* Process main tunables */
207 c->dthresh = dthresh;
209 c->on_eof = EOF_NONE;
213 /* Process eof_mode tunable */
215 if (strequal(eof_mode, "hinted")) {
216 c->on_eof = EOF_HINTED;
217 } else if (strequal(eof_mode, "growth")) {
218 c->on_eof = EOF_GROWTH;
222 fd = SMB_VFS_NEXT_OPEN(handle, smb_fname, fsp, flags, mode);
224 VFS_REMOVE_FSP_EXTENSION(handle, fsp);
228 /* EOF commit modes require us to know the initial file size. */
229 if (c && (c->on_eof != EOF_NONE)) {
231 if (SMB_VFS_FSTAT(fsp, &st) == -1) {
234 c->eof = st.st_ex_size;
240 static ssize_t commit_write(
241 vfs_handle_struct * handle,
247 ret = SMB_VFS_NEXT_WRITE(handle, fsp, data, count);
250 if (commit(handle, fsp, fsp->fh->pos, ret) == -1) {
258 static ssize_t commit_pwrite(
259 vfs_handle_struct * handle,
267 ret = SMB_VFS_NEXT_PWRITE(handle, fsp, data, count, offset);
269 if (commit(handle, fsp, offset, ret) == -1) {
277 static int commit_close(
278 vfs_handle_struct * handle,
281 /* Commit errors not checked, close() will find them again */
282 commit_all(handle, fsp);
283 return SMB_VFS_NEXT_CLOSE(handle, fsp);
286 static int commit_ftruncate(
287 vfs_handle_struct * handle,
293 result = SMB_VFS_NEXT_FTRUNCATE(handle, fsp, len);
295 struct commit_info *c;
296 if ((c = (struct commit_info *)VFS_FETCH_FSP_EXTENSION(
298 commit(handle, fsp, len, 0);
306 static struct vfs_fn_pointers vfs_commit_fns = {
307 .open_fn = commit_open,
308 .close_fn = commit_close,
309 .write = commit_write,
310 .pwrite = commit_pwrite,
311 .connect_fn = commit_connect,
312 .ftruncate = commit_ftruncate
315 NTSTATUS vfs_commit_init(void);
316 NTSTATUS vfs_commit_init(void)
318 return smb_register_vfs(SMB_VFS_INTERFACE_VERSION, MODULE,