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authorAndrew Tridgell <tridge@samba.org>2007-10-23 20:43:27 +1000
committerAndrew Tridgell <tridge@samba.org>2007-10-23 20:43:27 +1000
commite5830c1365b912dcfa8f528c443672fb2e2f7199 (patch)
treee49534cae925abb7f23d90d20ffc3f0ae0cf01cf /source3/modules
parente5fe5a569f5797a1b8528e836cd5b8f428840cee (diff)
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added a syncops VFS module for filesystems which do not guarantee meta-data operations are immediately committed to disk in stable form. Essential for clustered Samba setups
(This used to be commit 8b19cb17b9ae9e1cd4a96df6e7dedb75aff7ee96)
Diffstat (limited to 'source3/modules')
-rw-r--r--source3/modules/vfs_syncops.c210
1 files changed, 210 insertions, 0 deletions
diff --git a/source3/modules/vfs_syncops.c b/source3/modules/vfs_syncops.c
new file mode 100644
index 0000000000..3aa89b40a6
--- /dev/null
+++ b/source3/modules/vfs_syncops.c
@@ -0,0 +1,210 @@
+/*
+ * 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);
+ }
+}
+
+
+/*
+ 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)
+
+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,
+ const char *fname, files_struct *fsp, int flags, mode_t mode)
+{
+ SYNCOPS_NEXT(OPEN, (flags&O_CREAT?fname:NULL), (handle, 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, int fd)
+{
+ 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(fd);
+ }
+ return SMB_VFS_NEXT_CLOSE(handle, fsp, fd);
+}
+
+
+/* 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;
+}