Revert WAL posix_fallocate() patches.

This reverts commit 269e780822abb2e44189afaccd6b0ee7aefa7ddd
and commit 5b571bb8c8d2bea610e01ae1ee7bc05adcfff528.

Unfortunately, the initial patch had insufficient performance testing,
and resulted in a regression.

Per report by Thom Brown.

diff --git a/configure b/configure
index d4a544d5c8fc06f5b76b158872a5ab731799962a..c685ca3f918c9a5bdecf1ad7e83933073015824c 100755 (executable)
--- a/configure
+++ b/configure
@@ -19763,8 +19763,7 @@ LIBS=`echo "$LIBS" | sed -e 's/-ledit//g' -e 's/-lreadline//g'`
 
 
 
-
-for ac_func in cbrt dlopen fdatasync getifaddrs getpeerucred getrlimit mbstowcs_l memmove poll posix_fallocate pstat readlink setproctitle setsid sigprocmask symlink sync_file_range towlower utime utimes wcstombs wcstombs_l
+for ac_func in cbrt dlopen fdatasync getifaddrs getpeerucred getrlimit mbstowcs_l memmove poll pstat readlink setproctitle setsid sigprocmask symlink sync_file_range towlower utime utimes wcstombs wcstombs_l
 do
 as_ac_var=`$as_echo "ac_cv_func_$ac_func" | $as_tr_sh`
 { $as_echo "$as_me:$LINENO: checking for $ac_func" >&5

diff --git a/configure.in b/configure.in
index fe2541952f1e708e773efa6e0c847424d23f83e8..82771bddb12ab584c9ba4f42e8f39570372fe100 100644 (file)
--- a/configure.in
+++ b/configure.in
@@ -1230,7 +1230,7 @@ PGAC_FUNC_GETTIMEOFDAY_1ARG
 LIBS_including_readline="$LIBS"
 LIBS=`echo "$LIBS" | sed -e 's/-ledit//g' -e 's/-lreadline//g'`
 
-AC_CHECK_FUNCS([cbrt dlopen fdatasync getifaddrs getpeerucred getrlimit mbstowcs_l memmove poll posix_fallocate pstat readlink setproctitle setsid sigprocmask symlink sync_file_range towlower utime utimes wcstombs wcstombs_l])
+AC_CHECK_FUNCS([cbrt dlopen fdatasync getifaddrs getpeerucred getrlimit mbstowcs_l memmove poll pstat readlink setproctitle setsid sigprocmask symlink sync_file_range towlower utime utimes wcstombs wcstombs_l])
 
 AC_REPLACE_FUNCS(fseeko)
 case $host_os in

diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index 386811389d728da581bf6c5c30b7262d783e3f64..dc47c4760bf253e8855ad7b21ae2864f2a502367 100644 (file)
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -3353,10 +3353,11 @@ XLogFileInit(XLogSegNo logsegno, bool *use_existent, bool use_lock)
 {
        char            path[MAXPGPATH];
        char            tmppath[MAXPGPATH];
+       char       *zbuffer;
        XLogSegNo       installed_segno;
        int                     max_advance;
        int                     fd;
-       bool            zero_fill = true;
+       int                     nbytes;
 
        XLogFilePath(path, ThisTimeLineID, logsegno);
 
@@ -3390,6 +3391,16 @@ XLogFileInit(XLogSegNo logsegno, bool *use_existent, bool use_lock)
 
        unlink(tmppath);
 
+       /*
+        * Allocate a buffer full of zeros. This is done before opening the file
+        * so that we don't leak the file descriptor if palloc fails.
+        *
+        * Note: palloc zbuffer, instead of just using a local char array, to
+        * ensure it is reasonably well-aligned; this may save a few cycles
+        * transferring data to the kernel.
+        */
+       zbuffer = (char *) palloc0(XLOG_BLCKSZ);
+
        /* do not use get_sync_bit() here --- want to fsync only at end of fill */
        fd = BasicOpenFile(tmppath, O_RDWR | O_CREAT | O_EXCL | PG_BINARY,
                                           S_IRUSR | S_IWUSR);
@@ -3398,66 +3409,38 @@ XLogFileInit(XLogSegNo logsegno, bool *use_existent, bool use_lock)
                                (errcode_for_file_access(),
                                 errmsg("could not create file \"%s\": %m", tmppath)));
 
-#ifdef HAVE_POSIX_FALLOCATE
        /*
-        * If posix_fallocate() is available and succeeds, then the file is
-        * properly allocated and we don't need to zero-fill it (which is less
-        * efficient).  In case of an error, fall back to writing zeros, because on
-        * some platforms posix_fallocate() is available but will not always
-        * succeed in cases where zero-filling will.
+        * Zero-fill the file.  We have to do this the hard way to ensure that all
+        * the file space has really been allocated --- on platforms that allow
+        * "holes" in files, just seeking to the end doesn't allocate intermediate
+        * space.  This way, we know that we have all the space and (after the
+        * fsync below) that all the indirect blocks are down on disk.  Therefore,
+        * fdatasync(2) or O_DSYNC will be sufficient to sync future writes to the
+        * log file.
         */
-       if (posix_fallocate(fd, 0, XLogSegSize) == 0)
-               zero_fill = false;
-#endif /* HAVE_POSIX_FALLOCATE */
-
-       if (zero_fill)
+       for (nbytes = 0; nbytes < XLogSegSize; nbytes += XLOG_BLCKSZ)
        {
-               /*
-                * Allocate a buffer full of zeros. This is done before opening the
-                * file so that we don't leak the file descriptor if palloc fails.
-                *
-                * Note: palloc zbuffer, instead of just using a local char array, to
-                * ensure it is reasonably well-aligned; this may save a few cycles
-                * transferring data to the kernel.
-                */
-
-               char    *zbuffer = (char *) palloc0(XLOG_BLCKSZ);
-               int              nbytes;
-
-               /*
-                * Zero-fill the file. We have to do this the hard way to ensure that
-                * all the file space has really been allocated --- on platforms that
-                * allow "holes" in files, just seeking to the end doesn't allocate
-                * intermediate space.  This way, we know that we have all the space
-                * and (after the fsync below) that all the indirect blocks are down on
-                * disk. Therefore, fdatasync(2) or O_DSYNC will be sufficient to sync
-                * future writes to the log file.
-                */
-               for (nbytes = 0; nbytes < XLogSegSize; nbytes += XLOG_BLCKSZ)
+               errno = 0;
+               if ((int) write(fd, zbuffer, XLOG_BLCKSZ) != (int) XLOG_BLCKSZ)
                {
-                       errno = 0;
-                       if ((int) write(fd, zbuffer, XLOG_BLCKSZ) != (int) XLOG_BLCKSZ)
-                       {
-                               int                     save_errno = errno;
+                       int                     save_errno = errno;
 
-                               /*
-                                * If we fail to make the file, delete it to release disk space
-                                */
-                               unlink(tmppath);
+                       /*
+                        * If we fail to make the file, delete it to release disk space
+                        */
+                       unlink(tmppath);
 
-                               close(fd);
+                       close(fd);
 
-                               /* if write didn't set errno, assume no disk space */
-                               errno = save_errno ? save_errno : ENOSPC;
+                       /* if write didn't set errno, assume problem is no disk space */
+                       errno = save_errno ? save_errno : ENOSPC;
 
-                               ereport(ERROR,
-                                               (errcode_for_file_access(),
-                                                errmsg("could not write to file \"%s\": %m",
-                                                               tmppath)));
-                       }
+                       ereport(ERROR,
+                                       (errcode_for_file_access(),
+                                        errmsg("could not write to file \"%s\": %m", tmppath)));
                }
-               pfree(zbuffer);
        }
+       pfree(zbuffer);
 
        if (pg_fsync(fd) != 0)
        {

diff --git a/src/include/pg_config.h.in b/src/include/pg_config.h.in
index 033127beff86b6051a31c0a5c21ee1c393d47861..8aabf3c87a4706a2181f5d59eb93d8587ce65044 100644 (file)
--- a/src/include/pg_config.h.in
+++ b/src/include/pg_config.h.in
@@ -369,9 +369,6 @@
 /* Define to 1 if you have the `posix_fadvise' function. */
 #undef HAVE_POSIX_FADVISE
 
-/* Define to 1 if you have the `posix_fallocate' function. */
-#undef HAVE_POSIX_FALLOCATE
-
 /* Define to 1 if you have the POSIX signal interface. */
 #undef HAVE_POSIX_SIGNALS
 

diff --git a/src/include/pg_config.h.win32 b/src/include/pg_config.h.win32
index 931551086b7040a41ced9a29f42871753a72ad8f..54db287aff6178c81c1f794208459a40b5aea0e2 100644 (file)
--- a/src/include/pg_config.h.win32
+++ b/src/include/pg_config.h.win32
@@ -276,9 +276,6 @@
 /* Define to 1 if you have the <poll.h> header file. */
 /* #undef HAVE_POLL_H */
 
-/* Define to 1 if you have the `posix_fallocate' function. */
-/* #undef HAVE_POSIX_FALLOCATE */
-
 /* Define to 1 if you have the POSIX signal interface. */
 /* #undef HAVE_POSIX_SIGNALS */