On Wed, Apr 13, 2022 at 06:54:12AM -0500, Justin Pryzby wrote:
> I didn't pursue this patch, as it's easier for me to use /bin/sync -f.
> Someone
> should adopt it if interested.
I was about to start a new thread, but I found this one with some good
preliminary discussion. I came to the same conclusion about introducing a
new option instead of using syncfs() by default wherever it is available.
The attached patch is still a work-in-progress, but it seems to behave as
expected. I began investigating this because I noticed that the
sync-data-directory step on pg_upgrade takes quite a while when there are
many files, and I am looking for ways to reduce the amount of downtime
required for pg_upgrade.
The attached patch adds a new --sync-method option to the relevant frontend
utilities, but I am not wedded to that name/approach.
Thoughts?
--
Nathan Bossart
Amazon Web Services: https://aws.amazon.com
>From 4f484cd0268e63da8226d78dd21a8d7e29aa2b78 Mon Sep 17 00:00:00 2001
From: Nathan Bossart <nat...@postgresql.org>
Date: Fri, 28 Jul 2023 15:56:24 -0700
Subject: [PATCH v1 1/1] allow syncfs in frontend utilities
---
src/bin/initdb/initdb.c | 11 +++-
src/bin/pg_basebackup/pg_basebackup.c | 8 ++-
src/bin/pg_checksums/pg_checksums.c | 8 ++-
src/bin/pg_rewind/file_ops.c | 2 +-
src/bin/pg_rewind/pg_rewind.c | 8 +++
src/bin/pg_rewind/pg_rewind.h | 2 +
src/bin/pg_upgrade/option.c | 12 ++++
src/bin/pg_upgrade/pg_upgrade.c | 6 +-
src/bin/pg_upgrade/pg_upgrade.h | 1 +
src/common/file_utils.c | 79 ++++++++++++++++++++++++++-
src/fe_utils/option_utils.c | 18 ++++++
src/include/common/file_utils.h | 15 ++++-
src/include/fe_utils/option_utils.h | 3 +
src/include/storage/fd.h | 4 ++
src/tools/pgindent/typedefs.list | 1 +
15 files changed, 168 insertions(+), 10 deletions(-)
diff --git a/src/bin/initdb/initdb.c b/src/bin/initdb/initdb.c
index 3f4167682a..908263ee62 100644
--- a/src/bin/initdb/initdb.c
+++ b/src/bin/initdb/initdb.c
@@ -76,6 +76,7 @@
#include "common/restricted_token.h"
#include "common/string.h"
#include "common/username.h"
+#include "fe_utils/option_utils.h"
#include "fe_utils/string_utils.h"
#include "getopt_long.h"
#include "mb/pg_wchar.h"
@@ -165,6 +166,7 @@ static bool data_checksums = false;
static char *xlog_dir = NULL;
static char *str_wal_segment_size_mb = NULL;
static int wal_segment_size_mb;
+static SyncMethod sync_method = SYNC_METHOD_FSYNC;
/* internal vars */
@@ -3106,6 +3108,7 @@ main(int argc, char *argv[])
{"locale-provider", required_argument, NULL, 15},
{"icu-locale", required_argument, NULL, 16},
{"icu-rules", required_argument, NULL, 17},
+ {"sync-method", required_argument, NULL, 18},
{NULL, 0, NULL, 0}
};
@@ -3285,6 +3288,10 @@ main(int argc, char *argv[])
case 17:
icu_rules = pg_strdup(optarg);
break;
+ case 18:
+ if (!parse_sync_method(optarg, &sync_method))
+ exit(1);
+ break;
default:
/* getopt_long already emitted a complaint */
pg_log_error_hint("Try \"%s --help\" for more information.", progname);
@@ -3332,7 +3339,7 @@ main(int argc, char *argv[])
fputs(_("syncing data to disk ... "), stdout);
fflush(stdout);
- fsync_pgdata(pg_data, PG_VERSION_NUM);
+ fsync_pgdata(pg_data, PG_VERSION_NUM, sync_method);
check_ok();
return 0;
}
@@ -3409,7 +3416,7 @@ main(int argc, char *argv[])
{
fputs(_("syncing data to disk ... "), stdout);
fflush(stdout);
- fsync_pgdata(pg_data, PG_VERSION_NUM);
+ fsync_pgdata(pg_data, PG_VERSION_NUM, sync_method);
check_ok();
}
else
diff --git a/src/bin/pg_basebackup/pg_basebackup.c b/src/bin/pg_basebackup/pg_basebackup.c
index 1dc8efe0cb..548e764b2f 100644
--- a/src/bin/pg_basebackup/pg_basebackup.c
+++ b/src/bin/pg_basebackup/pg_basebackup.c
@@ -148,6 +148,7 @@ static bool verify_checksums = true;
static bool manifest = true;
static bool manifest_force_encode = false;
static char *manifest_checksums = NULL;
+static SyncMethod sync_method = SYNC_METHOD_FSYNC;
static bool success = false;
static bool made_new_pgdata = false;
@@ -2203,7 +2204,7 @@ BaseBackup(char *compression_algorithm, char *compression_detail,
}
else
{
- (void) fsync_pgdata(basedir, serverVersion);
+ (void) fsync_pgdata(basedir, serverVersion, sync_method);
}
}
@@ -2281,6 +2282,7 @@ main(int argc, char **argv)
{"no-manifest", no_argument, NULL, 5},
{"manifest-force-encode", no_argument, NULL, 6},
{"manifest-checksums", required_argument, NULL, 7},
+ {"sync-method", required_argument, NULL, 8},
{NULL, 0, NULL, 0}
};
int c;
@@ -2452,6 +2454,10 @@ main(int argc, char **argv)
case 7:
manifest_checksums = pg_strdup(optarg);
break;
+ case 8:
+ if (!parse_sync_method(optarg, &sync_method))
+ exit(1);
+ break;
default:
/* getopt_long already emitted a complaint */
pg_log_error_hint("Try \"%s --help\" for more information.", progname);
diff --git a/src/bin/pg_checksums/pg_checksums.c b/src/bin/pg_checksums/pg_checksums.c
index 19eb67e485..a1dfc51273 100644
--- a/src/bin/pg_checksums/pg_checksums.c
+++ b/src/bin/pg_checksums/pg_checksums.c
@@ -44,6 +44,7 @@ static char *only_filenode = NULL;
static bool do_sync = true;
static bool verbose = false;
static bool showprogress = false;
+static SyncMethod sync_method = SYNC_METHOD_FSYNC;
typedef enum
{
@@ -445,6 +446,7 @@ main(int argc, char *argv[])
{"no-sync", no_argument, NULL, 'N'},
{"progress", no_argument, NULL, 'P'},
{"verbose", no_argument, NULL, 'v'},
+ {"sync-method", required_argument, NULL, 1},
{NULL, 0, NULL, 0}
};
@@ -503,6 +505,10 @@ main(int argc, char *argv[])
case 'v':
verbose = true;
break;
+ case 1:
+ if (!parse_sync_method(optarg, &sync_method))
+ exit(1);
+ break;
default:
/* getopt_long already emitted a complaint */
pg_log_error_hint("Try \"%s --help\" for more information.", progname);
@@ -633,7 +639,7 @@ main(int argc, char *argv[])
if (do_sync)
{
pg_log_info("syncing data directory");
- fsync_pgdata(DataDir, PG_VERSION_NUM);
+ fsync_pgdata(DataDir, PG_VERSION_NUM, sync_method);
}
pg_log_info("updating control file");
diff --git a/src/bin/pg_rewind/file_ops.c b/src/bin/pg_rewind/file_ops.c
index 25996b4da4..451fb1856e 100644
--- a/src/bin/pg_rewind/file_ops.c
+++ b/src/bin/pg_rewind/file_ops.c
@@ -296,7 +296,7 @@ sync_target_dir(void)
if (!do_sync || dry_run)
return;
- fsync_pgdata(datadir_target, PG_VERSION_NUM);
+ fsync_pgdata(datadir_target, PG_VERSION_NUM, sync_method);
}
diff --git a/src/bin/pg_rewind/pg_rewind.c b/src/bin/pg_rewind/pg_rewind.c
index f7f3b8227f..a424762f1e 100644
--- a/src/bin/pg_rewind/pg_rewind.c
+++ b/src/bin/pg_rewind/pg_rewind.c
@@ -22,6 +22,7 @@
#include "common/file_perm.h"
#include "common/restricted_token.h"
#include "common/string.h"
+#include "fe_utils/option_utils.h"
#include "fe_utils/recovery_gen.h"
#include "fe_utils/string_utils.h"
#include "file_ops.h"
@@ -74,6 +75,7 @@ bool showprogress = false;
bool dry_run = false;
bool do_sync = true;
bool restore_wal = false;
+SyncMethod sync_method = SYNC_METHOD_FSYNC;
/* Target history */
TimeLineHistoryEntry *targetHistory;
@@ -131,6 +133,7 @@ main(int argc, char **argv)
{"no-sync", no_argument, NULL, 'N'},
{"progress", no_argument, NULL, 'P'},
{"debug", no_argument, NULL, 3},
+ {"sync-method", required_argument, NULL, 6},
{NULL, 0, NULL, 0}
};
int option_index;
@@ -218,6 +221,11 @@ main(int argc, char **argv)
config_file = pg_strdup(optarg);
break;
+ case 6:
+ if (!parse_sync_method(optarg, &sync_method))
+ exit(1);
+ break;
+
default:
/* getopt_long already emitted a complaint */
pg_log_error_hint("Try \"%s --help\" for more information.", progname);
diff --git a/src/bin/pg_rewind/pg_rewind.h b/src/bin/pg_rewind/pg_rewind.h
index ef8bdc1fbb..a7ce754880 100644
--- a/src/bin/pg_rewind/pg_rewind.h
+++ b/src/bin/pg_rewind/pg_rewind.h
@@ -13,6 +13,7 @@
#include "access/timeline.h"
#include "common/logging.h"
+#include "common/file_utils.h"
#include "datapagemap.h"
#include "libpq-fe.h"
#include "storage/block.h"
@@ -24,6 +25,7 @@ extern bool showprogress;
extern bool dry_run;
extern bool do_sync;
extern int WalSegSz;
+extern SyncMethod sync_method;
/* Target history */
extern TimeLineHistoryEntry *targetHistory;
diff --git a/src/bin/pg_upgrade/option.c b/src/bin/pg_upgrade/option.c
index 640361009e..4f9da8e685 100644
--- a/src/bin/pg_upgrade/option.c
+++ b/src/bin/pg_upgrade/option.c
@@ -14,6 +14,7 @@
#endif
#include "common/string.h"
+#include "fe_utils/option_utils.h"
#include "getopt_long.h"
#include "pg_upgrade.h"
#include "utils/pidfile.h"
@@ -57,12 +58,14 @@ parseCommandLine(int argc, char *argv[])
{"verbose", no_argument, NULL, 'v'},
{"clone", no_argument, NULL, 1},
{"copy", no_argument, NULL, 2},
+ {"sync-method", required_argument, NULL, 3},
{NULL, 0, NULL, 0}
};
int option; /* Command line option */
int optindex = 0; /* used by getopt_long */
int os_user_effective_id;
+ SyncMethod unused;
user_opts.do_sync = true;
user_opts.transfer_mode = TRANSFER_MODE_COPY;
@@ -199,6 +202,12 @@ parseCommandLine(int argc, char *argv[])
user_opts.transfer_mode = TRANSFER_MODE_COPY;
break;
+ case 3:
+ if (!parse_sync_method(optarg, &unused))
+ exit(1);
+ user_opts.sync_method = pg_strdup(optarg);
+ break;
+
default:
fprintf(stderr, _("Try \"%s --help\" for more information.\n"),
os_info.progname);
@@ -209,6 +218,9 @@ parseCommandLine(int argc, char *argv[])
if (optind < argc)
pg_fatal("too many command-line arguments (first is \"%s\")", argv[optind]);
+ if (!user_opts.sync_method)
+ user_opts.sync_method = pg_strdup("fsync");
+
if (log_opts.verbose)
pg_log(PG_REPORT, "Running in verbose mode");
diff --git a/src/bin/pg_upgrade/pg_upgrade.c b/src/bin/pg_upgrade/pg_upgrade.c
index 4562dafcff..96bfb67167 100644
--- a/src/bin/pg_upgrade/pg_upgrade.c
+++ b/src/bin/pg_upgrade/pg_upgrade.c
@@ -192,8 +192,10 @@ main(int argc, char **argv)
{
prep_status("Sync data directory to disk");
exec_prog(UTILITY_LOG_FILE, NULL, true, true,
- "\"%s/initdb\" --sync-only \"%s\"", new_cluster.bindir,
- new_cluster.pgdata);
+ "\"%s/initdb\" --sync-only \"%s\" --sync-method %s",
+ new_cluster.bindir,
+ new_cluster.pgdata,
+ user_opts.sync_method);
check_ok();
}
diff --git a/src/bin/pg_upgrade/pg_upgrade.h b/src/bin/pg_upgrade/pg_upgrade.h
index 3eea0139c7..13457b2f75 100644
--- a/src/bin/pg_upgrade/pg_upgrade.h
+++ b/src/bin/pg_upgrade/pg_upgrade.h
@@ -304,6 +304,7 @@ typedef struct
transferMode transfer_mode; /* copy files or link them? */
int jobs; /* number of processes/threads to use */
char *socketdir; /* directory to use for Unix sockets */
+ char *sync_method;
} UserOpts;
typedef struct
diff --git a/src/common/file_utils.c b/src/common/file_utils.c
index 74833c4acb..b3d814d0c4 100644
--- a/src/common/file_utils.c
+++ b/src/common/file_utils.c
@@ -51,6 +51,33 @@ static void walkdir(const char *path,
int (*action) (const char *fname, bool isdir),
bool process_symlinks);
+#ifdef HAVE_SYNCFS
+static void
+do_syncfs(const char *path)
+{
+ int fd;
+
+ fd = open(path, O_RDONLY | PG_BINARY, 0);
+
+ if (fd < 0)
+ {
+ if (errno == EACCES || errno == EISDIR)
+ return;
+ pg_log_error("could not open file \"%s\": %m", path);
+ return;
+ }
+
+ if (syncfs(fd) < 0)
+ {
+ pg_log_error("could not synchronize file system for file \"%s\": %m", path);
+ (void) close(fd);
+ exit(EXIT_FAILURE);
+ }
+
+ (void) close(fd);
+}
+#endif
+
/*
* Issue fsync recursively on PGDATA and all its contents.
*
@@ -63,7 +90,8 @@ static void walkdir(const char *path,
*/
void
fsync_pgdata(const char *pg_data,
- int serverVersion)
+ int serverVersion,
+ SyncMethod sync_method)
{
bool xlog_is_symlink;
char pg_wal[MAXPGPATH];
@@ -89,6 +117,55 @@ fsync_pgdata(const char *pg_data,
xlog_is_symlink = true;
}
+#ifdef HAVE_SYNCFS
+ if (sync_method == SYNC_METHOD_SYNCFS)
+ {
+ DIR *dir;
+ struct dirent *de;
+
+ /*
+ * On Linux, we don't have to open every single file one by one. We
+ * can use syncfs() to sync whole filesystems. We only expect
+ * filesystem boundaries to exist where we tolerate symlinks, namely
+ * pg_wal and the tablespaces, so we call syncfs() for each of those
+ * directories.
+ */
+
+ /* Sync the top level pgdata directory. */
+ do_syncfs(pg_data);
+
+ /* If any tablespaces are configured, sync each of those. */
+ dir = opendir(pg_tblspc);
+ if (dir == NULL)
+ pg_log_error("could not open directory \"%s\": %m", pg_tblspc);
+ else
+ {
+ while (errno = 0, (de = readdir(dir)) != NULL)
+ {
+ char subpath[MAXPGPATH * 2];
+
+ if (strcmp(de->d_name, ".") == 0 ||
+ strcmp(de->d_name, "..") == 0)
+ continue;
+
+ snprintf(subpath, sizeof(subpath), "%s/%s", pg_tblspc, de->d_name);
+ do_syncfs(subpath);
+ }
+
+ if (errno)
+ pg_log_error("could not read directory \"%s\": %m", pg_tblspc);
+
+ (void) closedir(dir);
+ }
+
+ /* If pg_wal is a symlink, process that too. */
+ if (xlog_is_symlink)
+ do_syncfs(pg_wal);
+
+ return;
+ }
+#endif /* HAVE_SYNCFS */
+
/*
* If possible, hint to the kernel that we're soon going to fsync the data
* directory and its contents.
diff --git a/src/fe_utils/option_utils.c b/src/fe_utils/option_utils.c
index 763c991015..c65aedf8f5 100644
--- a/src/fe_utils/option_utils.c
+++ b/src/fe_utils/option_utils.c
@@ -82,3 +82,21 @@ option_parse_int(const char *optarg, const char *optname,
*result = val;
return true;
}
+
+bool
+parse_sync_method(const char *optarg, SyncMethod *sync_method)
+{
+ if (strcmp(optarg, "fsync") == 0)
+ *sync_method = SYNC_METHOD_FSYNC;
+#ifdef HAVE_SYNCFS
+ else if (strcmp(optarg, "syncfs") == 0)
+ *sync_method = SYNC_METHOD_SYNCFS;
+#endif
+ else
+ {
+ pg_log_error("unrecognized sync method: %s", optarg);
+ return false;
+ }
+
+ return true;
+}
diff --git a/src/include/common/file_utils.h b/src/include/common/file_utils.h
index b7efa1226d..fd5162fef1 100644
--- a/src/include/common/file_utils.h
+++ b/src/include/common/file_utils.h
@@ -27,12 +27,23 @@ typedef enum PGFileType
struct iovec; /* avoid including port/pg_iovec.h here */
#ifdef FRONTEND
+
+typedef enum SyncMethod
+{
+ SYNC_METHOD_FSYNC,
+#ifdef HAVE_SYNCFS
+ SYNC_METHOD_SYNCFS
+#endif
+} SyncMethod;
+
extern int fsync_fname(const char *fname, bool isdir);
-extern void fsync_pgdata(const char *pg_data, int serverVersion);
+extern void fsync_pgdata(const char *pg_data, int serverVersion,
+ SyncMethod sync_method);
extern void fsync_dir_recurse(const char *dir);
extern int durable_rename(const char *oldfile, const char *newfile);
extern int fsync_parent_path(const char *fname);
-#endif
+
+#endif /* FRONTEND */
extern PGFileType get_dirent_type(const char *path,
const struct dirent *de,
diff --git a/src/include/fe_utils/option_utils.h b/src/include/fe_utils/option_utils.h
index b7b0654cee..3ad8737219 100644
--- a/src/include/fe_utils/option_utils.h
+++ b/src/include/fe_utils/option_utils.h
@@ -14,6 +14,8 @@
#include "postgres_fe.h"
+#include "common/file_utils.h"
+
typedef void (*help_handler) (const char *progname);
extern void handle_help_version_opts(int argc, char *argv[],
@@ -22,5 +24,6 @@ extern void handle_help_version_opts(int argc, char *argv[],
extern bool option_parse_int(const char *optarg, const char *optname,
int min_range, int max_range,
int *result);
+extern bool parse_sync_method(const char *optarg, SyncMethod *sync_method);
#endif /* OPTION_UTILS_H */
diff --git a/src/include/storage/fd.h b/src/include/storage/fd.h
index 6791a406fc..196f20e716 100644
--- a/src/include/storage/fd.h
+++ b/src/include/storage/fd.h
@@ -43,6 +43,8 @@
#ifndef FD_H
#define FD_H
+#ifndef FRONTEND
+
#include <dirent.h>
#include <fcntl.h>
@@ -195,6 +197,8 @@ extern int durable_unlink(const char *fname, int elevel);
extern void SyncDataDirectory(void);
extern int data_sync_elevel(int elevel);
+#endif /* ! FRONTEND */
+
/* Filename components */
#define PG_TEMP_FILES_DIR "pgsql_tmp"
#define PG_TEMP_FILE_PREFIX "pgsql_tmp"
diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list
index 11d47294cf..3bbf70fdf3 100644
--- a/src/tools/pgindent/typedefs.list
+++ b/src/tools/pgindent/typedefs.list
@@ -2678,6 +2678,7 @@ SupportRequestSelectivity
SupportRequestSimplify
SupportRequestWFuncMonotonic
Syn
+SyncMethod
SyncOps
SyncRepConfigData
SyncRepStandbyData
--
2.25.1
