--- /dev/null
+/*
+ * Copyright (c) James Peach 2006
+ *
+ * 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"
+
+/* Commit data module.
+ *
+ * The purpose of this module is to flush data to disk at regular intervals,
+ * just like the NFS commit operation. There's two rationales for this. First,
+ * it minimises the data loss in case of a power outage without incurring
+ * the poor performance of synchronous I/O. Second, a steady flush rate
+ * can produce better throughput than suddenly dumping massive amounts of
+ * writes onto a disk.
+ *
+ * Tunables:
+ *
+ * commit: dthresh Amount of dirty data that can accumulate
+ * before we commit (sync) it.
+ *
+ * commit: debug Debug level at which to emit messages.
+ *
+ */
+
+#define MODULE "commit"
+
+static int module_debug;
+
+struct commit_info
+{
+ SMB_OFF_T dbytes; /* Dirty (uncommitted) bytes */
+ SMB_OFF_T dthresh; /* Dirty data threshold */
+};
+
+static SMB_OFF_T conv_str_size(const char * str)
+{
+ SMB_OFF_T lval;
+ char * end;
+
+ if (str == NULL || *str == '\0') {
+ return 0;
+ }
+
+ if (sizeof(SMB_OFF_T) == 8) {
+ lval = strtoull(str, &end, 10 /* base */);
+ } else {
+ lval = strtoul(str, &end, 10 /* base */);
+ }
+
+ if (end == NULL || end == str) {
+ return 0;
+ }
+
+ if (*end) {
+ if (strwicmp(end, "K") == 0) {
+ lval *= 1024ULL;
+ } else if (strwicmp(end, "M") == 0) {
+ lval *= (1024ULL * 1024ULL);
+ } else if (strwicmp(end, "G") == 0) {
+ lval *= (1024ULL * 1024ULL * 1024ULL);
+ } else if (strwicmp(end, "T") == 0) {
+ lval *= (1024ULL * 1024ULL * 1024ULL * 1024ULL);
+ } else if (strwicmp(end, "P") == 0) {
+ lval *= (1024ULL * 1024ULL * 1024ULL * 1024ULL * 1024ULL);
+ } else {
+ return 0;
+ }
+ }
+
+ return lval;
+}
+
+static void commit_all(
+ struct vfs_handle_struct * handle,
+ files_struct * fsp)
+{
+ struct commit_info *c;
+
+ if ((c = VFS_FETCH_FSP_EXTENSION(handle, fsp))) {
+ if (c->dbytes) {
+ DEBUG(module_debug,
+ ("%s: flushing %lu dirty bytes\n",
+ MODULE, (unsigned long)c->dbytes));
+
+ fdatasync(fsp->fh->fd);
+ c->dbytes = 0;
+ }
+ }
+}
+
+static void commit(
+ struct vfs_handle_struct * handle,
+ files_struct * fsp,
+ ssize_t last_write)
+{
+ struct commit_info *c;
+
+ if ((c = VFS_FETCH_FSP_EXTENSION(handle, fsp))) {
+
+ if (last_write > 0) {
+ c->dbytes += last_write;
+ }
+
+ if (c->dbytes > c->dthresh) {
+ DEBUG(module_debug,
+ ("%s: flushing %lu dirty bytes\n",
+ MODULE, (unsigned long)c->dbytes));
+
+ fdatasync(fsp->fh->fd);
+ c->dbytes = 0;
+ }
+ }
+}
+
+static int commit_connect(
+ struct vfs_handle_struct * handle,
+ const char * service,
+ const char * user)
+{
+ module_debug = lp_parm_int(SNUM(handle->conn), MODULE, "debug", 100);
+ return SMB_VFS_NEXT_CONNECT(handle, service, user);
+}
+
+static int commit_open(
+ vfs_handle_struct * handle,
+ const char * fname,
+ files_struct * fsp,
+ int flags,
+ mode_t mode)
+{
+ SMB_OFF_T dthresh;
+
+ /* Don't bother with read-only files. */
+ if ((flags & O_ACCMODE) == O_RDONLY) {
+ return SMB_VFS_NEXT_OPEN(handle, fname, fsp, flags, mode);
+ }
+
+ dthresh = conv_str_size(lp_parm_const_string(SNUM(handle->conn),
+ MODULE, "dthresh", NULL));
+
+ if (dthresh > 0) {
+ struct commit_info * c;
+ c = VFS_ADD_FSP_EXTENSION(handle, fsp, struct commit_info);
+ if (c) {
+ c->dthresh = dthresh;
+ c->dbytes = 0;
+ }
+ }
+
+ return SMB_VFS_NEXT_OPEN(handle, fname, fsp, flags, mode);
+}
+
+static ssize_t commit_write(
+ vfs_handle_struct * handle,
+ files_struct * fsp,
+ int fd,
+ void * data,
+ size_t count)
+{
+ ssize_t ret;
+
+ ret = SMB_VFS_NEXT_WRITE(handle, fsp, fd, data, count);
+ commit(handle, fsp, ret);
+
+ return ret;
+}
+
+static ssize_t commit_pwrite(
+ vfs_handle_struct * handle,
+ files_struct * fsp,
+ int fd,
+ void * data,
+ size_t count,
+ SMB_OFF_T offset)
+{
+ ssize_t ret;
+
+ ret = SMB_VFS_NEXT_PWRITE(handle, fsp, fd, data, count, offset);
+ commit(handle, fsp, ret);
+
+ return ret;
+}
+
+static ssize_t commit_close(
+ vfs_handle_struct * handle,
+ files_struct * fsp,
+ int fd)
+{
+ commit_all(handle, fsp);
+ return SMB_VFS_NEXT_CLOSE(handle, fsp, fd);
+}
+
+static vfs_op_tuple commit_ops [] =
+{
+ {SMB_VFS_OP(commit_open),
+ SMB_VFS_OP_OPEN, SMB_VFS_LAYER_TRANSPARENT},
+ {SMB_VFS_OP(commit_close),
+ SMB_VFS_OP_CLOSE, SMB_VFS_LAYER_TRANSPARENT},
+ {SMB_VFS_OP(commit_write),
+ SMB_VFS_OP_WRITE, SMB_VFS_LAYER_TRANSPARENT},
+ {SMB_VFS_OP(commit_pwrite),
+ SMB_VFS_OP_PWRITE, SMB_VFS_LAYER_TRANSPARENT},
+ {SMB_VFS_OP(commit_connect),
+ SMB_VFS_OP_CONNECT, SMB_VFS_LAYER_TRANSPARENT},
+
+ {SMB_VFS_OP(NULL), SMB_VFS_OP_NOOP, SMB_VFS_LAYER_NOOP}
+};
+
+NTSTATUS vfs_commit_init(void)
+{
+ return smb_register_vfs(SMB_VFS_INTERFACE_VERSION, MODULE, commit_ops);
+}
+
git.samba.org / import / samba-svnimport.git / commitdiff