@ -51,19 +51,52 @@ static void walkdir(const char *path,
int ( * action ) ( const char * fname , bool isdir ) , int ( * action ) ( const char * fname , bool isdir ) ,
bool process_symlinks ) ; bool process_symlinks ) ;
# ifdef HAVE_SYNCFS
/*
/*
* Issue fsync recursively on PGDATA and all its contents . * do_syncfs - - Try to syncfs a file system
* *
* We fsync regular files and directories wherever they are , but we follow * Reports errors trying to open the path . syncfs ( ) errors are fatal .
*/
static void
do_syncfs ( const char * path )
{
int fd ;
fd = open ( path , O_RDONLY , 0 ) ;
if ( fd < 0 )
{
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 /* HAVE_SYNCFS */
/*
* Synchronize PGDATA and all its contents .
*
* We sync regular files and directories wherever they are , but we follow
* symlinks only for pg_wal ( or pg_xlog ) and immediately under pg_tblspc . * symlinks only for pg_wal ( or pg_xlog ) and immediately under pg_tblspc .
* Other symlinks are presumed to point at files we ' re not responsible for * Other symlinks are presumed to point at files we ' re not responsible for
* fsyncing , and might not have privileges to write at all . * syncing , and might not have privileges to write at all .
* *
* serverVersion indicates the version of the server to be fsync ' d . * serverVersion indicates the version of the server to be sync ' d .
*/ */
void void
fsync_pgdata ( const char * pg_data , sync_pgdata ( const char * pg_data ,
int serverVersion ) int serverVersion ,
DataDirSyncMethod sync_method )
{ {
bool xlog_is_symlink ; bool xlog_is_symlink ;
char pg_wal [ MAXPGPATH ] ; char pg_wal [ MAXPGPATH ] ;
@ -89,49 +122,135 @@ fsync_pgdata(const char *pg_data,
xlog_is_symlink = true ; xlog_is_symlink = true ;
} }
/*
switch ( sync_method )
* If possible , hint to the kernel that we ' re soon going to fsync the data {
* directory and its contents . case DATA_DIR_SYNC_METHOD_SYNCFS :
*/ {
# ifndef HAVE_SYNCFS
pg_log_error ( " this build does not support sync method \" %s \" " ,
" syncfs " ) ;
exit ( EXIT_FAILURE ) ;
# else
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 ) ;
# endif /* HAVE_SYNCFS */
}
break ;
case DATA_DIR_SYNC_METHOD_FSYNC :
{
/*
* If possible , hint to the kernel that we ' re soon going to
* fsync the data directory and its contents .
*/
# ifdef PG_FLUSH_DATA_WORKS # ifdef PG_FLUSH_DATA_WORKS
walkdir ( pg_data , pre_sync_fname , false ) ; walkdir ( pg_data , pre_sync_fname , false ) ;
if ( xlog_is_symlink ) if ( xlog_is_symlink )
walkdir ( pg_wal , pre_sync_fname , false ) ; walkdir ( pg_wal , pre_sync_fname , false ) ;
walkdir ( pg_tblspc , pre_sync_fname , true ) ; walkdir ( pg_tblspc , pre_sync_fname , true ) ;
# endif # endif
/*
/*
* Now we do the fsync ( ) s in the same order . * Now we do the fsync ( ) s in the same order .
* *
* The main call ignores symlinks , so in addition to specially processing * The main call ignores symlinks , so in addition to specially
* pg_wal if it ' s a symlink , pg_tblspc has to be visited separately with * processing pg_wal if it ' s a symlink , pg_tblspc has to be
* process_symlinks = true . Note that if there are any plain directories * visited separately with process_symlinks = true . Note that
* in pg_tblspc , they ' ll get fsync ' d twice . That ' s not an expected case * if there are any plain directories in pg_tblspc , they ' ll
* so we don ' t worry about optimizing it . * get fsync ' d twice . That ' s not an expected case so we don ' t
*/ * worry about optimizing it .
walkdir ( pg_data , fsync_fname , false ) ; */
if ( xlog_is_symlink ) walkdir ( pg_data , fsync_fname , false ) ;
walkdir ( pg_wal , fsync_fname , false ) ; if ( xlog_is_symlink )
walkdir ( pg_tblspc , fsync_fname , true ) ; walkdir ( pg_wal , fsync_fname , false ) ;
walkdir ( pg_tblspc , fsync_fname , true ) ;
}
break ;
}
} }
/*
/*
* Issue fsync recursively on the given directory and all its contents . * Synchronize the given directory and all its contents .
* *
* This is a convenient wrapper on top of walkdir ( ) . * This is a convenient wrapper on top of walkdir ( ) and do_syncfs ( ) .
*/ */
void void
fsync_dir_recurse ( const char * dir ) sync_dir_recurse ( const char * dir , DataDirSyncMethod sync_method )
{ {
/*
switch ( sync_method )
* If possible , hint to the kernel that we ' re soon going to fsync the data {
* directory and its contents . case DATA_DIR_SYNC_METHOD_SYNCFS :
*/ {
# ifndef HAVE_SYNCFS
pg_log_error ( " this build does not support sync method \" %s \" " ,
" syncfs " ) ;
exit ( EXIT_FAILURE ) ;
# else
/*
* On Linux , we don ' t have to open every single file one by
* one . We can use syncfs ( ) to sync the whole filesystem .
*/
do_syncfs ( dir ) ;
# endif /* HAVE_SYNCFS */
}
break ;
case DATA_DIR_SYNC_METHOD_FSYNC :
{
/*
* If possible , hint to the kernel that we ' re soon going to
* fsync the data directory and its contents .
*/
# ifdef PG_FLUSH_DATA_WORKS # ifdef PG_FLUSH_DATA_WORKS
walkdir ( dir , pre_sync_fname , false ) ; walkdir ( dir , pre_sync_fname , false ) ;
# endif # endif
walkdir ( dir , fsync_fname , false ) ; walkdir ( dir , fsync_fname , false ) ;
}
break ;
}
} }
/*
/*
Nathan Bossart
2 years ago