Changeset: 848010420450 for MonetDB
URL: https://dev.monetdb.org/hg/MonetDB?cmd=changeset;node=848010420450
Modified Files:
tools/merovingian/daemon/snapshot.c
Branch: hot-snapshot
Log Message:
Fsync appropriately when restoring a snapshot
diffs (176 lines):
diff --git a/tools/merovingian/daemon/snapshot.c
b/tools/merovingian/daemon/snapshot.c
--- a/tools/merovingian/daemon/snapshot.c
+++ b/tools/merovingian/daemon/snapshot.c
@@ -14,6 +14,7 @@
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
+#include <sys/fcntl.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <time.h>
@@ -24,6 +25,12 @@
#include "stream.h"
#include "utils/database.h"
+struct dir_helper {
+ char *dir;
+ int fd;
+};
+
+static err prepare_directory(struct dir_helper *state, char *prefix_dir, char
*dir);
static bool parse_snapshot_name(const char *filename, char **dbname, time_t
*timestamp);
static err validate_location(const char *path);
static err unpack_tarstream(stream *tarstream, char *destdir, int
skipcomponents);
@@ -408,6 +415,106 @@ bailout:
return e;
}
+/* Create the directory 'filename' is in, if necessary, and take care
+ * of fsync'ing it first when called with a different `dir`. Wrap up if
+ * filename is set to NULL.
+ */
+static err
+prepare_directory(struct dir_helper *state, char *prefix_dir, char *filename)
+{
+ char *e = NO_ERR;
+ size_t file_len;
+ size_t prefix_len;
+ int ret;
+ int fd;
+ char *dir_buf = NULL;
+ char *dir = NULL;
+
+ if (filename != NULL) {
+ dir_buf = strdup(filename);
+ dir = dirname(dir_buf);
+ }
+
+ // If we are already tracking a directory and this one is the same,
+ // there's no need to do anything.
+ if (dir != NULL && state->dir != NULL && strcmp(state->dir, dir) == 0) {
+ free(dir_buf);
+ return NULL;
+ }
+
+ // Before switching to the new directory, first fsync the old one, if
any.
+ if (state->dir != NULL) {
+ if (fsync(state->fd) < 0) {
+ e = newErr("fsync %s: %s", state->dir, strerror(errno));
+ goto bailout;
+ }
+ if (close(state->fd) < 0) {
+ e = newErr("close %s: %s", state->dir, strerror(errno));
+ state->fd = 0;
+ goto bailout;
+ }
+ state->fd = -1;
+ free(state->dir);
+ state->dir = NULL;
+ }
+
+ if (dir == NULL) {
+ // no new directory to set up, we just had to sync the current
one
+ return NO_ERR;
+ }
+
+ // Error checking on the new file.
+ file_len = strlen(filename);
+ prefix_len = strlen(prefix_dir);
+ if (prefix_len > file_len || strncmp(filename, prefix_dir, prefix_len)
!= 0) {
+ e = newErr("File '%s' is not inside prefix '%s'", filename,
prefix_dir);
+ goto bailout;
+ }
+
+ // Create any missing directories beyond the prefix.
+ for (char *p = dir + prefix_len + 1; *p != '\0'; p++) {
+ if (*p == '/') {
+ *p = '\0';
+ ret = mkdir(dir, 0755);
+ if (ret < 0 && errno != EEXIST) {
+ e = newErr("Could not create directory %s: %s",
dir, strerror(errno));
+ *p = '/';
+ goto bailout;
+ }
+ *p = '/';
+ }
+ }
+ // The final part of the directory is not covered by the loop above
+ ret = mkdir(dir, 0755);
+ if (ret < 0 && errno != EEXIST) {
+ e = newErr("Could not create directory %s: %s", dir,
strerror(errno));
+ goto bailout;
+ }
+
+ // Open the directory so we can fsync it later
+ fd = open(dir, O_RDONLY);
+ if (fd < 0) {
+ e = newErr("couldn't open directory %s: %s", dir,
strerror(errno));
+ goto bailout;
+ }
+
+ state->fd = fd;
+ state->dir = strdup(dir);
+
+ free(dir_buf);
+ return NULL;
+bailout:
+ free(dir_buf);
+ if (state->fd > 0) {
+ close(state->fd);
+ state->fd = -1;
+ }
+ free(state->dir);
+ state->dir = NULL;
+ return e;
+}
+
+
#define TAR_BLOCK_SIZE (512)
/* Read a full block from the stream.
@@ -488,6 +595,7 @@ unpack_tarstream(stream *tarstream, char
char *whole_filename = NULL;
char *destfile = NULL;
FILE *outfile = NULL;
+ struct dir_helper dirhelper = {NULL};
while (read_tar_block(tarstream, block, &e) >= 0) {
if (e != NO_ERR)
@@ -513,18 +621,8 @@ unpack_tarstream(stream *tarstream, char
destfile = realloc(destfile, strlen(destdir) + 1 +
strlen(useful_part) + 1);
sprintf(destfile, "%s/%s", destdir, useful_part);
- // Create any missing directories
- for (char *p = destfile + strlen(destdir) + 1; *p != '\0'; p++)
{
- if (*p == '/') {
- *p = '\0';
- int ret = mkdir(destfile, 0755);
- if (ret < 0 && errno != EEXIST) {
- e = newErr("Could not create directory
%s: %s", destfile, strerror(errno));
- goto bailout;
- }
- *p = '/';
- }
- }
+ // Create any missing directories and take care of fsync'ing
them
+ prepare_directory(&dirhelper, destdir, destfile);
// Copy the data
outfile = fopen(destfile, "w");
@@ -550,9 +648,15 @@ unpack_tarstream(stream *tarstream, char
}
size -= TAR_BLOCK_SIZE;
}
+
+ if (fsync(fileno(outfile)) < 0) {
+ e = newErr("fsync %s: %s", destfile, strerror(errno));
+ goto bailout;
+ }
fclose(outfile);
outfile = NULL;
}
+ prepare_directory(&dirhelper, NULL, NULL);
bailout:
if (outfile != NULL)
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