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* Copyright (c) James Peach 2006, 2007
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* Copyright (c) David Losada Carballo 2007
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 3 of the License, or
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* (at your option) any later version.
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, see <http://www.gnu.org/licenses/>.
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/* Commit data module.
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* The purpose of this module is to flush data to disk at regular intervals,
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* just like the NFS commit operation. There's two rationales for this. First,
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* it minimises the data loss in case of a power outage without incurring
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* the poor performance of synchronous I/O. Second, a steady flush rate
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* can produce better throughput than suddenly dumping massive amounts of
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* commit: dthresh Amount of dirty data that can accumulate
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* before we commit (sync) it.
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* commit: debug Debug level at which to emit messages.
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* commit: eof mode String. Tunes how the module tries to guess when
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* the client has written the last bytes of the file.
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* Possible values (default = hinted):
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* (*) = hinted Some clients (i.e. Windows Explorer) declare the
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* size of the file before transferring it. With this
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* option, we remember that hint, and commit after
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* writing in that file position. If the client
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* doesn't declare the size of file, commiting on EOF
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* = growth Commits after a write operation has made the file
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* size grow. If the client declares a file size, it
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* refrains to commit until the file has reached it.
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* Useful for defeating writeback on NFS shares.
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#define MODULE "commit"
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static int module_debug;
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/* For chunk-based commits */
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SMB_OFF_T dbytes; /* Dirty (uncommitted) bytes */
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SMB_OFF_T dthresh; /* Dirty data threshold */
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/* For commits on EOF */
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SMB_OFF_T eof; /* Expected file size */
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struct commit_info * c,
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("%s: flushing %lu dirty bytes\n",
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MODULE, (unsigned long)c->dbytes));
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result = fdatasync(fd);
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c->dbytes = 0; /* on success, no dirty bytes */
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static int commit_all(
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struct vfs_handle_struct * handle,
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struct commit_info *c;
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if ((c = VFS_FETCH_FSP_EXTENSION(handle, fsp))) {
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("%s: flushing %lu dirty bytes\n",
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MODULE, (unsigned long)c->dbytes));
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return commit_do(c, fsp->fh->fd);
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struct vfs_handle_struct * handle,
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struct commit_info *c;
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if ((c = VFS_FETCH_FSP_EXTENSION(handle, fsp)) == NULL) {
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c->dbytes += last_write; /* dirty bytes always counted */
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if (c->dthresh && (c->dbytes > c->dthresh)) {
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return commit_do(c, fsp->fh->fd);
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/* Return if we are not in EOF mode or if we have temporarily opted
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if (c->on_eof == EOF_NONE || c->eof < 0) {
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/* This write hit or went past our cache the file size. */
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if ((offset + last_write) >= c->eof) {
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if (commit_do(c, fsp->fh->fd) == -1) {
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/* Hinted mode only commits the first time we hit EOF. */
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if (c->on_eof == EOF_HINTED) {
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} else if (c->on_eof == EOF_GROWTH) {
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c->eof = offset + last_write;
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static int commit_connect(
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struct vfs_handle_struct * handle,
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const char * service,
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module_debug = lp_parm_int(SNUM(handle->conn), MODULE, "debug", 100);
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return SMB_VFS_NEXT_CONNECT(handle, service, user);
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static int commit_open(
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vfs_handle_struct * handle,
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const char *eof_mode;
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struct commit_info *c = NULL;
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/* Don't bother with read-only files. */
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if ((flags & O_ACCMODE) == O_RDONLY) {
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return SMB_VFS_NEXT_OPEN(handle, fname, fsp, flags, mode);
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/* Read and check module configuration */
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dthresh = conv_str_size(lp_parm_const_string(SNUM(handle->conn),
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MODULE, "dthresh", NULL));
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eof_mode = lp_parm_const_string(SNUM(handle->conn),
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MODULE, "eof mode", "none");
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if (dthresh > 0 || !strequal(eof_mode, "none")) {
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c = VFS_ADD_FSP_EXTENSION(handle, fsp, struct commit_info, NULL);
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/* Process main tunables */
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c->dthresh = dthresh;
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c->on_eof = EOF_NONE;
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/* Process eof_mode tunable */
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if (strequal(eof_mode, "hinted")) {
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c->on_eof = EOF_HINTED;
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} else if (strequal(eof_mode, "growth")) {
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c->on_eof = EOF_GROWTH;
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fd = SMB_VFS_NEXT_OPEN(handle, fname, fsp, flags, mode);
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VFS_REMOVE_FSP_EXTENSION(handle, fsp);
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/* EOF commit modes require us to know the initial file size. */
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if (c && (c->on_eof != EOF_NONE)) {
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if (SMB_VFS_FSTAT(fsp, &st) == -1) {
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static ssize_t commit_write(
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vfs_handle_struct * handle,
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ret = SMB_VFS_NEXT_WRITE(handle, fsp, data, count);
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if (commit(handle, fsp, fsp->fh->pos, ret) == -1) {
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static ssize_t commit_pwrite(
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vfs_handle_struct * handle,
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ret = SMB_VFS_NEXT_PWRITE(handle, fsp, data, count, offset);
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if (commit(handle, fsp, offset, ret) == -1) {
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static int commit_close(
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vfs_handle_struct * handle,
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/* Commit errors not checked, close() will find them again */
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commit_all(handle, fsp);
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return SMB_VFS_NEXT_CLOSE(handle, fsp);
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static int commit_ftruncate(
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vfs_handle_struct * handle,
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result = SMB_VFS_NEXT_FTRUNCATE(handle, fsp, len);
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struct commit_info *c;
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if ((c = VFS_FETCH_FSP_EXTENSION(handle, fsp))) {
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commit(handle, fsp, len, 0);
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static vfs_op_tuple commit_ops [] =
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{SMB_VFS_OP(commit_open),
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SMB_VFS_OP_OPEN, SMB_VFS_LAYER_TRANSPARENT},
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{SMB_VFS_OP(commit_close),
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SMB_VFS_OP_CLOSE, SMB_VFS_LAYER_TRANSPARENT},
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{SMB_VFS_OP(commit_write),
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SMB_VFS_OP_WRITE, SMB_VFS_LAYER_TRANSPARENT},
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{SMB_VFS_OP(commit_pwrite),
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SMB_VFS_OP_PWRITE, SMB_VFS_LAYER_TRANSPARENT},
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{SMB_VFS_OP(commit_connect),
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SMB_VFS_OP_CONNECT, SMB_VFS_LAYER_TRANSPARENT},
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{SMB_VFS_OP(commit_ftruncate),
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SMB_VFS_OP_FTRUNCATE, SMB_VFS_LAYER_TRANSPARENT},
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{SMB_VFS_OP(NULL), SMB_VFS_OP_NOOP, SMB_VFS_LAYER_NOOP}
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NTSTATUS vfs_commit_init(void);
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NTSTATUS vfs_commit_init(void)
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return smb_register_vfs(SMB_VFS_INTERFACE_VERSION, MODULE, commit_ops);