From 1d4a0ab19a7e45aa8b94d7f720d1d9cefb81ec40 Mon Sep 17 00:00:00 2001
From: Andres Freund <andres@anarazel.de>
Date: Wed, 9 Mar 2016 18:53:53 -0800
Subject: [PATCH] Avoid unlikely data-loss scenarios due to rename() without
fsync.
Renaming a file using rename(2) is not guaranteed to be durable in face
of crashes. Use the previously added durable_rename()/durable_link_or_rename()
in various places where we previously just renamed files.
Most of the changed call sites are arguably not critical, but it seems
better to err on the side of too much durability. The most prominent
known case where the previously missing fsyncs could cause data loss is
crashes at the end of a checkpoint. After the actual checkpoint has been
performed, old WAL files are recycled. When they're filled, their
contents are fdatasynced, but we did not fsync the containing
directory. An OS/hardware crash in an unfortunate moment could then end
up leaving that file with its old name, but new content; WAL replay
would thus not replay it.
Reported-By: Tomas Vondra
Author: Michael Paquier, Tomas Vondra, Andres Freund
Discussion: 56583BDD.9060302@2ndquadrant.com
Backpatch: All supported branches
---
.../pg_stat_statements/pg_stat_statements.c | 6 +-
src/backend/access/transam/timeline.c | 40 ++-----------
src/backend/access/transam/xlog.c | 56 ++++---------------
src/backend/access/transam/xlogarchive.c | 13 +----
src/backend/postmaster/pgarch.c | 6 +-
src/backend/replication/logical/origin.c | 23 +-------
src/backend/utils/misc/guc.c | 6 +-
7 files changed, 24 insertions(+), 126 deletions(-)
diff --git a/contrib/pg_stat_statements/pg_stat_statements.c b/contrib/pg_stat_statements/pg_stat_statements.c
index dffc4778fa8..9ce60e696c9 100644
--- a/contrib/pg_stat_statements/pg_stat_statements.c
+++ b/contrib/pg_stat_statements/pg_stat_statements.c
@@ -741,11 +741,7 @@ pgss_shmem_shutdown(int code, Datum arg)
/*
* Rename file into place, so we atomically replace any old one.
*/
- if (rename(PGSS_DUMP_FILE ".tmp", PGSS_DUMP_FILE) != 0)
- ereport(LOG,
- (errcode_for_file_access(),
- errmsg("could not rename pg_stat_statement file \"%s\": %m",
- PGSS_DUMP_FILE ".tmp")));
+ (void) durable_rename(PGSS_DUMP_FILE ".tmp", PGSS_DUMP_FILE, LOG);
/* Unlink query-texts file; it's not needed while shutdown */
unlink(PGSS_TEXT_FILE);
diff --git a/src/backend/access/transam/timeline.c b/src/backend/access/transam/timeline.c
index f6da673477a..bd91573708b 100644
--- a/src/backend/access/transam/timeline.c
+++ b/src/backend/access/transam/timeline.c
@@ -418,24 +418,10 @@ writeTimeLineHistory(TimeLineID newTLI, TimeLineID parentTLI,
TLHistoryFilePath(path, newTLI);
/*
- * Prefer link() to rename() here just to be really sure that we don't
- * overwrite an existing file. However, there shouldn't be one, so
- * rename() is an acceptable substitute except for the truly paranoid.
+ * Perform the rename using link if available, paranoidly trying to avoid
+ * overwriting an existing file (there shouldn't be one).
*/
-#if HAVE_WORKING_LINK
- if (link(tmppath, path) < 0)
- ereport(ERROR,
- (errcode_for_file_access(),
- errmsg("could not link file \"%s\" to \"%s\": %m",
- tmppath, path)));
- unlink(tmppath);
-#else
- if (rename(tmppath, path) < 0)
- ereport(ERROR,
- (errcode_for_file_access(),
- errmsg("could not rename file \"%s\" to \"%s\": %m",
- tmppath, path)));
-#endif
+ durable_link_or_rename(tmppath, path, ERROR);
/* The history file can be archived immediately. */
if (XLogArchivingActive())
@@ -508,24 +494,10 @@ writeTimeLineHistoryFile(TimeLineID tli, char *content, int size)
TLHistoryFilePath(path, tli);
/*
- * Prefer link() to rename() here just to be really sure that we don't
- * overwrite an existing logfile. However, there shouldn't be one, so
- * rename() is an acceptable substitute except for the truly paranoid.
+ * Perform the rename using link if available, paranoidly trying to avoid
+ * overwriting an existing file (there shouldn't be one).
*/
-#if HAVE_WORKING_LINK
- if (link(tmppath, path) < 0)
- ereport(ERROR,
- (errcode_for_file_access(),
- errmsg("could not link file \"%s\" to \"%s\": %m",
- tmppath, path)));
- unlink(tmppath);
-#else
- if (rename(tmppath, path) < 0)
- ereport(ERROR,
- (errcode_for_file_access(),
- errmsg("could not rename file \"%s\" to \"%s\": %m",
- tmppath, path)));
-#endif
+ durable_link_or_rename(tmppath, path, ERROR);
}
/*
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index 00f139a0f38..5b1c3611176 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -3299,34 +3299,16 @@ InstallXLogFileSegment(XLogSegNo *segno, char *tmppath,
}
/*
- * Prefer link() to rename() here just to be really sure that we don't
- * overwrite an existing logfile. However, there shouldn't be one, so
- * rename() is an acceptable substitute except for the truly paranoid.
+ * Perform the rename using link if available, paranoidly trying to avoid
+ * overwriting an existing file (there shouldn't be one).
*/
-#if HAVE_WORKING_LINK
- if (link(tmppath, path) < 0)
+ if (durable_link_or_rename(tmppath, path, LOG) != 0)
{
if (use_lock)
LWLockRelease(ControlFileLock);
- ereport(LOG,
- (errcode_for_file_access(),
- errmsg("could not link file \"%s\" to \"%s\" (initialization of log file): %m",
- tmppath, path)));
- return false;
- }
- unlink(tmppath);
-#else
- if (rename(tmppath, path) < 0)
- {
- if (use_lock)
- LWLockRelease(ControlFileLock);
- ereport(LOG,
- (errcode_for_file_access(),
- errmsg("could not rename file \"%s\" to \"%s\" (initialization of log file): %m",
- tmppath, path)));
+ /* durable_link_or_rename already emitted log message */
return false;
}
-#endif
if (use_lock)
LWLockRelease(ControlFileLock);
@@ -5339,11 +5321,7 @@ exitArchiveRecovery(TimeLineID endTLI, XLogRecPtr endOfLog)
* re-enter archive recovery mode in a subsequent crash.
*/
unlink(RECOVERY_COMMAND_DONE);
- if (rename(RECOVERY_COMMAND_FILE, RECOVERY_COMMAND_DONE) != 0)
- ereport(FATAL,
- (errcode_for_file_access(),
- errmsg("could not rename file \"%s\" to \"%s\": %m",
- RECOVERY_COMMAND_FILE, RECOVERY_COMMAND_DONE)));
+ durable_rename(RECOVERY_COMMAND_FILE, RECOVERY_COMMAND_DONE, FATAL);
ereport(LOG,
(errmsg("archive recovery complete")));
@@ -6190,7 +6168,7 @@ StartupXLOG(void)
if (stat(TABLESPACE_MAP, &st) == 0)
{
unlink(TABLESPACE_MAP_OLD);
- if (rename(TABLESPACE_MAP, TABLESPACE_MAP_OLD) == 0)
+ if (durable_rename(TABLESPACE_MAP, TABLESPACE_MAP_OLD, DEBUG1) == 0)
ereport(LOG,
(errmsg("ignoring file \"%s\" because no file \"%s\" exists",
TABLESPACE_MAP, BACKUP_LABEL_FILE),
@@ -6553,11 +6531,7 @@ StartupXLOG(void)
if (haveBackupLabel)
{
unlink(BACKUP_LABEL_OLD);
- if (rename(BACKUP_LABEL_FILE, BACKUP_LABEL_OLD) != 0)
- ereport(FATAL,
- (errcode_for_file_access(),
- errmsg("could not rename file \"%s\" to \"%s\": %m",
- BACKUP_LABEL_FILE, BACKUP_LABEL_OLD)));
+ durable_rename(BACKUP_LABEL_FILE, BACKUP_LABEL_OLD, FATAL);
}
/*
@@ -6570,11 +6544,7 @@ StartupXLOG(void)
if (haveTblspcMap)
{
unlink(TABLESPACE_MAP_OLD);
- if (rename(TABLESPACE_MAP, TABLESPACE_MAP_OLD) != 0)
- ereport(FATAL,
- (errcode_for_file_access(),
- errmsg("could not rename file \"%s\" to \"%s\": %m",
- TABLESPACE_MAP, TABLESPACE_MAP_OLD)));
+ durable_rename(TABLESPACE_MAP, TABLESPACE_MAP_OLD, FATAL);
}
/* Check that the GUCs used to generate the WAL allow recovery */
@@ -7351,11 +7321,7 @@ StartupXLOG(void)
*/
XLogArchiveCleanup(partialfname);
- if (rename(origpath, partialpath) != 0)
- ereport(ERROR,
- (errcode_for_file_access(),
- errmsg("could not rename file \"%s\" to \"%s\": %m",
- origpath, partialpath)));
+ durable_rename(origpath, partialpath, ERROR);
XLogArchiveNotify(partialfname);
}
}
@@ -10911,7 +10877,7 @@ CancelBackup(void)
/* remove leftover file from previously canceled backup if it exists */
unlink(BACKUP_LABEL_OLD);
- if (rename(BACKUP_LABEL_FILE, BACKUP_LABEL_OLD) != 0)
+ if (durable_rename(BACKUP_LABEL_FILE, BACKUP_LABEL_OLD, DEBUG1) != 0)
{
ereport(WARNING,
(errcode_for_file_access(),
@@ -10934,7 +10900,7 @@ CancelBackup(void)
/* remove leftover file from previously canceled backup if it exists */
unlink(TABLESPACE_MAP_OLD);
- if (rename(TABLESPACE_MAP, TABLESPACE_MAP_OLD) == 0)
+ if (durable_rename(TABLESPACE_MAP, TABLESPACE_MAP_OLD, DEBUG1) == 0)
{
ereport(LOG,
(errmsg("online backup mode canceled"),
diff --git a/src/backend/access/transam/xlogarchive.c b/src/backend/access/transam/xlogarchive.c
index 277c14a8104..d153a44ea9a 100644
--- a/src/backend/access/transam/xlogarchive.c
+++ b/src/backend/access/transam/xlogarchive.c
@@ -470,11 +470,7 @@ KeepFileRestoredFromArchive(char *path, char *xlogfname)
reload = true;
}
- if (rename(path, xlogfpath) < 0)
- ereport(ERROR,
- (errcode_for_file_access(),
- errmsg("could not rename file \"%s\" to \"%s\": %m",
- path, xlogfpath)));
+ durable_rename(path, xlogfpath, ERROR);
/*
* Create .done file forcibly to prevent the restored segment from being
@@ -580,12 +576,7 @@ XLogArchiveForceDone(const char *xlog)
StatusFilePath(archiveReady, xlog, ".ready");
if (stat(archiveReady, &stat_buf) == 0)
{
- if (rename(archiveReady, archiveDone) < 0)
- ereport(WARNING,
- (errcode_for_file_access(),
- errmsg("could not rename file \"%s\" to \"%s\": %m",
- archiveReady, archiveDone)));
-
+ (void) durable_rename(archiveReady, archiveDone, WARNING);
return;
}
diff --git a/src/backend/postmaster/pgarch.c b/src/backend/postmaster/pgarch.c
index 397f8024e28..1aa6466d67f 100644
--- a/src/backend/postmaster/pgarch.c
+++ b/src/backend/postmaster/pgarch.c
@@ -728,9 +728,5 @@ pgarch_archiveDone(char *xlog)
StatusFilePath(rlogready, xlog, ".ready");
StatusFilePath(rlogdone, xlog, ".done");
- if (rename(rlogready, rlogdone) < 0)
- ereport(WARNING,
- (errcode_for_file_access(),
- errmsg("could not rename file \"%s\" to \"%s\": %m",
- rlogready, rlogdone)));
+ (void) durable_rename(rlogready, rlogdone, WARNING);
}
diff --git a/src/backend/replication/logical/origin.c b/src/backend/replication/logical/origin.c
index 7e2307f5f22..8c8833b71d0 100644
--- a/src/backend/replication/logical/origin.c
+++ b/src/backend/replication/logical/origin.c
@@ -604,29 +604,10 @@ CheckPointReplicationOrigin(void)
tmppath)));
}
- /* fsync the temporary file */
- if (pg_fsync(tmpfd) != 0)
- {
- CloseTransientFile(tmpfd);
- ereport(PANIC,
- (errcode_for_file_access(),
- errmsg("could not fsync file \"%s\": %m",
- tmppath)));
- }
-
CloseTransientFile(tmpfd);
- /* rename to permanent file, fsync file and directory */
- if (rename(tmppath, path) != 0)
- {
- ereport(PANIC,
- (errcode_for_file_access(),
- errmsg("could not rename file \"%s\" to \"%s\": %m",
- tmppath, path)));
- }
-
- fsync_fname(path, false);
- fsync_fname("pg_logical", true);
+ /* fsync, rename to permanent file, fsync file and directory */
+ durable_rename(tmppath, path, PANIC);
}
/*
diff --git a/src/backend/utils/misc/guc.c b/src/backend/utils/misc/guc.c
index ea5a09ac1be..0be64a1c9f3 100644
--- a/src/backend/utils/misc/guc.c
+++ b/src/backend/utils/misc/guc.c
@@ -7037,11 +7037,7 @@ AlterSystemSetConfigFile(AlterSystemStmt *altersysstmt)
* at worst it can lose the parameters set by last ALTER SYSTEM
* command.
*/
- if (rename(AutoConfTmpFileName, AutoConfFileName) < 0)
- ereport(ERROR,
- (errcode_for_file_access(),
- errmsg("could not rename file \"%s\" to \"%s\": %m",
- AutoConfTmpFileName, AutoConfFileName)));
+ durable_rename(AutoConfTmpFileName, AutoConfFileName, ERROR);
}
PG_CATCH();
{
--
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