Remove HAVE_WORKING_LINK

Previously, hard links were not used on Windows and Cygwin, but they
support them just fine in currently supported OS versions, so we can
use them there as well.

Since all supported platforms now support hard links, we can remove
the alternative code paths.

Rename durable_link_or_rename() to durable_rename_excl() to make the
purpose more clear without referencing the implementation details.

Discussion: https://www.postgresql.org/message-id/flat/72fff73f-dc9c-4ef4-83e8-d2e60c98df48%402ndquadrant.com

diff --git a/src/backend/access/transam/timeline.c b/src/backend/access/transam/timeline.c
index 57ee4e048b0a584ad488068b948f2ed4993a54bb..860a9964146947afe8a0f2188786a8a3fdbe4af3 100644 (file)
--- a/src/backend/access/transam/timeline.c
+++ b/src/backend/access/transam/timeline.c
@@ -429,7 +429,7 @@ writeTimeLineHistory(TimeLineID newTLI, TimeLineID parentTLI,
         * Perform the rename using link if available, paranoidly trying to avoid
         * overwriting an existing file (there shouldn't be one).
         */
-       durable_link_or_rename(tmppath, path, ERROR);
+       durable_rename_excl(tmppath, path, ERROR);
 
        /* The history file can be archived immediately. */
        if (XLogArchivingActive())
@@ -507,7 +507,7 @@ writeTimeLineHistoryFile(TimeLineID tli, char *content, int size)
         * Perform the rename using link if available, paranoidly trying to avoid
         * overwriting an existing file (there shouldn't be one).
         */
-       durable_link_or_rename(tmppath, path, ERROR);
+       durable_rename_excl(tmppath, path, ERROR);
 }
 
 /*

diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index bffa94f36e4c01c41ba1c91fbdcc6aff24d7cdb9..614a25242b5cd3f763c8ebe8f4ec2972cd017a57 100644 (file)
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -3591,11 +3591,11 @@ InstallXLogFileSegment(XLogSegNo *segno, char *tmppath,
         * Perform the rename using link if available, paranoidly trying to avoid
         * overwriting an existing file (there shouldn't be one).
         */
-       if (durable_link_or_rename(tmppath, path, LOG) != 0)
+       if (durable_rename_excl(tmppath, path, LOG) != 0)
        {
                if (use_lock)
                        LWLockRelease(ControlFileLock);
-               /* durable_link_or_rename already emitted log message */
+               /* durable_rename_excl already emitted log message */
                return false;
        }
 

diff --git a/src/backend/storage/file/fd.c b/src/backend/storage/file/fd.c
index 34f7443110a0e28edbbb34533f1303d6521ac3aa..7dc6dd2f1593167a05e368a7ca487707e620e5e8 100644 (file)
--- a/src/backend/storage/file/fd.c
+++ b/src/backend/storage/file/fd.c
@@ -765,10 +765,11 @@ durable_unlink(const char *fname, int elevel)
 }
 
 /*
- * durable_link_or_rename -- rename a file in a durable manner.
+ * durable_rename_excl -- rename a file in a durable manner, without
+ * overwriting an existing target file
  *
- * Similar to durable_rename(), except that this routine tries (but does not
- * guarantee) not to overwrite the target file.
+ * Similar to durable_rename(), except that this routine will fail if the
+ * target file already exists.
  *
  * Note that a crash in an unfortunate moment can leave you with two links to
  * the target file.
@@ -779,7 +780,7 @@ durable_unlink(const char *fname, int elevel)
  * valid upon return.
  */
 int
-durable_link_or_rename(const char *oldfile, const char *newfile, int elevel)
+durable_rename_excl(const char *oldfile, const char *newfile, int elevel)
 {
        /*
         * Ensure that, if we crash directly after the rename/link, a file with
@@ -788,7 +789,6 @@ durable_link_or_rename(const char *oldfile, const char *newfile, int elevel)
        if (fsync_fname_ext(oldfile, false, false, elevel) != 0)
                return -1;
 
-#ifdef HAVE_WORKING_LINK
        if (link(oldfile, newfile) < 0)
        {
                ereport(elevel,
@@ -798,17 +798,6 @@ durable_link_or_rename(const char *oldfile, const char *newfile, int elevel)
                return -1;
        }
        unlink(oldfile);
-#else
-       /* XXX: Add racy file existence check? */
-       if (rename(oldfile, newfile) < 0)
-       {
-               ereport(elevel,
-                               (errcode_for_file_access(),
-                                errmsg("could not rename file \"%s\" to \"%s\": %m",
-                                               oldfile, newfile)));
-               return -1;
-       }
-#endif
 
        /*
         * Make change persistent in case of an OS crash, both the new entry and

diff --git a/src/include/pg_config_manual.h b/src/include/pg_config_manual.h
index b4ce53300b39e5462243c3d22f9ae8a3ce79f5a8..d74a8dd8083b9cc2bf9260a9b83ae3efa24ceef2 100644 (file)
--- a/src/include/pg_config_manual.h
+++ b/src/include/pg_config_manual.h
@@ -129,13 +129,6 @@
 #undef HAVE_UNIX_SOCKETS
 #endif
 
-/*
- * Define this if your operating system supports link()
- */
-#if !defined(WIN32) && !defined(__CYGWIN__)
-#define HAVE_WORKING_LINK 1
-#endif
-
 /*
  * USE_POSIX_FADVISE controls whether Postgres will attempt to use the
  * posix_fadvise() kernel call.  Usually the automatic configure tests are

diff --git a/src/include/storage/fd.h b/src/include/storage/fd.h
index 2085c62b41d883ca4e01ae2d6bc46e34480bd13c..8cd125d7dfaa65b4e74138fed9ac1ccefc9b9ecd 100644 (file)
--- a/src/include/storage/fd.h
+++ b/src/include/storage/fd.h
@@ -157,7 +157,7 @@ extern void fsync_fname(const char *fname, bool isdir);
 extern int     fsync_fname_ext(const char *fname, bool isdir, bool ignore_perm, int elevel);
 extern int     durable_rename(const char *oldfile, const char *newfile, int loglevel);
 extern int     durable_unlink(const char *fname, int loglevel);
-extern int     durable_link_or_rename(const char *oldfile, const char *newfile, int loglevel);
+extern int     durable_rename_excl(const char *oldfile, const char *newfile, int loglevel);
 extern void SyncDataDirectory(void);
 extern int     data_sync_elevel(int elevel);