From 066bc21c0e085e2642ff25cc665c4efad3669d6f Mon Sep 17 00:00:00 2001 From: Tom Lane Date: Mon, 4 Dec 2017 18:37:54 -0500 Subject: [PATCH] Simplify do_pg_start_backup's API by opening pg_tblspc internally. do_pg_start_backup() expects its callers to pass in an open DIR pointer for the pg_tblspc directory, but there's no apparent advantage in that. It complicates the callers without adding any flexibility, and there's no robustness advantage, since we surely have to be prepared for errors during the scan of pg_tblspc anyway. In fact, by holding an extra kernel resource during operations like the preliminary checkpoint, we might be making things a fraction more failure-prone not less. Hence, remove that argument and open the directory just for the duration of the actual scan. Discussion: https://postgr.es/m/28752.1512413887@sss.pgh.pa.us --- src/backend/access/transam/xlog.c | 6 ++++-- src/backend/access/transam/xlogfuncs.c | 15 ++------------- src/backend/replication/basebackup.c | 19 ++++--------------- src/include/access/xlog.h | 2 +- 4 files changed, 11 insertions(+), 31 deletions(-) diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c index a11406c741..e46ee553d6 100644 --- a/src/backend/access/transam/xlog.c +++ b/src/backend/access/transam/xlog.c @@ -10206,7 +10206,7 @@ XLogFileNameP(TimeLineID tli, XLogSegNo segno) */ XLogRecPtr do_pg_start_backup(const char *backupidstr, bool fast, TimeLineID *starttli_p, - StringInfo labelfile, DIR *tblspcdir, List **tablespaces, + StringInfo labelfile, List **tablespaces, StringInfo tblspcmapfile, bool infotbssize, bool needtblspcmapfile) { @@ -10297,6 +10297,7 @@ do_pg_start_backup(const char *backupidstr, bool fast, TimeLineID *starttli_p, PG_ENSURE_ERROR_CLEANUP(pg_start_backup_callback, (Datum) BoolGetDatum(exclusive)); { bool gotUniqueStartpoint = false; + DIR *tblspcdir; struct dirent *de; tablespaceinfo *ti; int datadirpathlen; @@ -10428,6 +10429,7 @@ do_pg_start_backup(const char *backupidstr, bool fast, TimeLineID *starttli_p, datadirpathlen = strlen(DataDir); /* Collect information about all tablespaces */ + tblspcdir = AllocateDir("pg_tblspc"); while ((de = ReadDir(tblspcdir, "pg_tblspc")) != NULL) { char fullpath[MAXPGPATH + 10]; @@ -10476,7 +10478,6 @@ do_pg_start_backup(const char *backupidstr, bool fast, TimeLineID *starttli_p, appendStringInfoChar(&buflinkpath, *s++); } - /* * Relpath holds the relative path of the tablespace directory * when it's located within PGDATA, or NULL if it's located @@ -10511,6 +10512,7 @@ do_pg_start_backup(const char *backupidstr, bool fast, TimeLineID *starttli_p, errmsg("tablespaces are not supported on this platform"))); #endif } + FreeDir(tblspcdir); /* * Construct backup label file diff --git a/src/backend/access/transam/xlogfuncs.c b/src/backend/access/transam/xlogfuncs.c index 48d85c1ce5..c41428ea2a 100644 --- a/src/backend/access/transam/xlogfuncs.c +++ b/src/backend/access/transam/xlogfuncs.c @@ -75,7 +75,6 @@ pg_start_backup(PG_FUNCTION_ARGS) bool exclusive = PG_GETARG_BOOL(2); char *backupidstr; XLogRecPtr startpoint; - DIR *dir; SessionBackupState status = get_backup_status(); backupidstr = text_to_cstring(backupid); @@ -85,18 +84,10 @@ pg_start_backup(PG_FUNCTION_ARGS) (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE), errmsg("a backup is already in progress in this session"))); - /* Make sure we can open the directory with tablespaces in it */ - dir = AllocateDir("pg_tblspc"); - if (!dir) - ereport(ERROR, - (errcode_for_file_access(), - errmsg("could not open directory \"%s\": %m", - "pg_tblspc"))); - if (exclusive) { startpoint = do_pg_start_backup(backupidstr, fast, NULL, NULL, - dir, NULL, NULL, false, true); + NULL, NULL, false, true); } else { @@ -112,13 +103,11 @@ pg_start_backup(PG_FUNCTION_ARGS) MemoryContextSwitchTo(oldcontext); startpoint = do_pg_start_backup(backupidstr, fast, NULL, label_file, - dir, NULL, tblspc_map_file, false, true); + NULL, tblspc_map_file, false, true); before_shmem_exit(nonexclusive_base_backup_cleanup, (Datum) 0); } - FreeDir(dir); - PG_RETURN_LSN(startpoint); } diff --git a/src/backend/replication/basebackup.c b/src/backend/replication/basebackup.c index b264b69aef..cd7d391b2f 100644 --- a/src/backend/replication/basebackup.c +++ b/src/backend/replication/basebackup.c @@ -64,7 +64,7 @@ static int64 _tarWriteDir(const char *pathbuf, int basepathlen, struct stat *sta static void send_int8_string(StringInfoData *buf, int64 intval); static void SendBackupHeader(List *tablespaces); static void base_backup_cleanup(int code, Datum arg); -static void perform_base_backup(basebackup_options *opt, DIR *tblspcdir); +static void perform_base_backup(basebackup_options *opt); static void parse_basebackup_options(List *options, basebackup_options *opt); static void SendXlogRecPtrResult(XLogRecPtr ptr, TimeLineID tli); static int compareWalFileNames(const void *a, const void *b); @@ -188,7 +188,7 @@ base_backup_cleanup(int code, Datum arg) * clobbered by longjmp" from stupider versions of gcc. */ static void -perform_base_backup(basebackup_options *opt, DIR *tblspcdir) +perform_base_backup(basebackup_options *opt) { XLogRecPtr startptr; TimeLineID starttli; @@ -207,7 +207,7 @@ perform_base_backup(basebackup_options *opt, DIR *tblspcdir) tblspc_map_file = makeStringInfo(); startptr = do_pg_start_backup(opt->label, opt->fastcheckpoint, &starttli, - labelfile, tblspcdir, &tablespaces, + labelfile, &tablespaces, tblspc_map_file, opt->progress, opt->sendtblspcmapfile); @@ -690,7 +690,6 @@ parse_basebackup_options(List *options, basebackup_options *opt) void SendBaseBackup(BaseBackupCmd *cmd) { - DIR *dir; basebackup_options opt; parse_basebackup_options(cmd->options, &opt); @@ -706,17 +705,7 @@ SendBaseBackup(BaseBackupCmd *cmd) set_ps_display(activitymsg, false); } - /* Make sure we can open the directory with tablespaces in it */ - dir = AllocateDir("pg_tblspc"); - if (!dir) - ereport(ERROR, - (errcode_for_file_access(), - errmsg("could not open directory \"%s\": %m", - "pg_tblspc"))); - - perform_base_backup(&opt, dir); - - FreeDir(dir); + perform_base_backup(&opt); } static void diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h index 8fd6010ba0..dd7d8b5e40 100644 --- a/src/include/access/xlog.h +++ b/src/include/access/xlog.h @@ -310,7 +310,7 @@ typedef enum SessionBackupState } SessionBackupState; extern XLogRecPtr do_pg_start_backup(const char *backupidstr, bool fast, - TimeLineID *starttli_p, StringInfo labelfile, DIR *tblspcdir, + TimeLineID *starttli_p, StringInfo labelfile, List **tablespaces, StringInfo tblspcmapfile, bool infotbssize, bool needtblspcmapfile); extern XLogRecPtr do_pg_stop_backup(char *labelfile, bool waitforarchive, -- 2.40.0