file_utils.h File Reference

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Functions
int	fsync_fname (const char *fname, bool isdir)
void	fsync_pgdata (const char *pg_data, int serverVersion)
void	fsync_dir_recurse (const char *dir)
int	durable_rename (const char *oldfile, const char *newfile)
int	fsync_parent_path (const char *fname)

Function Documentation

durable_rename()

int durable_rename	(	const char *	oldfile,
		const char *	newfile
	)

Definition at line 340 of file file_utils.c.

References close, fd(), fsync, fsync_fname(), fsync_parent_path(), PG_BINARY, and pg_log_error.

{
    int         fd;

    /*
     * First fsync the old and target path (if it exists), to ensure that they
     * are properly persistent on disk. Syncing the target file is not
     * strictly necessary, but it makes it easier to reason about crashes;
     * because it's then guaranteed that either source or target file exists
     * after a crash.
     */
    if (fsync_fname(oldfile, false) != 0)
        return -1;

    fd = open(newfile, PG_BINARY | O_RDWR, 0);
    if (fd < 0)
    {
        if (errno != ENOENT)
        {
            pg_log_error("could not open file \"%s\": %m", newfile);
            return -1;
        }
    }
    else
    {
        if (fsync(fd) != 0)
        {
            pg_log_error("could not fsync file \"%s\": %m", newfile);
            close(fd);
            return -1;
        }
        close(fd);
    }

    /* Time to do the real deal... */
    if (rename(oldfile, newfile) != 0)
    {
        pg_log_error("could not rename file \"%s\" to \"%s\": %m",
                     oldfile, newfile);
        return -1;
    }

    /*
     * To guarantee renaming the file is persistent, fsync the file with its
     * new name, and its containing directory.
     */
    if (fsync_fname(newfile, false) != 0)
        return -1;

    if (fsync_parent_path(newfile) != 0)
        return -1;

    return 0;
}

fsync_dir_recurse()

void fsync_dir_recurse

(

const char *

dir

)

Definition at line 122 of file file_utils.c.

References fsync_fname(), and walkdir().

Referenced by _CloseArchive(), and BaseBackup().

{
    /*
     * If possible, hint to the kernel that we're soon going to fsync the data
     * directory and its contents.
     */
#ifdef PG_FLUSH_DATA_WORKS
    walkdir(dir, pre_sync_fname, false);
#endif

    walkdir(dir, fsync_fname, false);
}

fsync_fname()

int fsync_fname	(	const char *	fname,
		bool	isdir
	)

Definition at line 617 of file fd.c.

{
    fsync_fname_ext(fname, isdir, false, data_sync_elevel(ERROR));
}

fsync_parent_path()

int fsync_parent_path

(

const char *

fname

)

Definition at line 313 of file file_utils.c.

References fsync_fname(), get_parent_directory(), MAXPGPATH, and strlcpy().

Referenced by durable_rename().

{
    char        parentpath[MAXPGPATH];

    strlcpy(parentpath, fname, MAXPGPATH);
    get_parent_directory(parentpath);

    /*
     * get_parent_directory() returns an empty string if the input argument is
     * just a file name (see comments in path.c), so handle that as being the
     * current directory.
     */
    if (strlen(parentpath) == 0)
        strlcpy(parentpath, ".", MAXPGPATH);

    if (fsync_fname(parentpath, true) != 0)
        return -1;

    return 0;
}

fsync_pgdata()

void fsync_pgdata	(	const char *	pg_data,
		int	serverVersion
	)

Definition at line 58 of file file_utils.c.

References fsync_fname(), lstat, MAXPGPATH, MINIMUM_VERSION_FOR_PG_WAL, pg_log_error, pgwin32_is_junction(), snprintf, stat, and walkdir().

Referenced by BaseBackup(), main(), and syncTargetDirectory().

{
    bool        xlog_is_symlink;
    char        pg_wal[MAXPGPATH];
    char        pg_tblspc[MAXPGPATH];

    /* handle renaming of pg_xlog to pg_wal in post-10 clusters */
    snprintf(pg_wal, MAXPGPATH, "%s/%s", pg_data,
             serverVersion < MINIMUM_VERSION_FOR_PG_WAL ? "pg_xlog" : "pg_wal");
    snprintf(pg_tblspc, MAXPGPATH, "%s/pg_tblspc", pg_data);

    /*
     * If pg_wal is a symlink, we'll need to recurse into it separately,
     * because the first walkdir below will ignore it.
     */
    xlog_is_symlink = false;

#ifndef WIN32
    {
        struct stat st;

        if (lstat(pg_wal, &st) < 0)
            pg_log_error("could not stat file \"%s\": %m", pg_wal);
        else if (S_ISLNK(st.st_mode))
            xlog_is_symlink = true;
    }
#else
    if (pgwin32_is_junction(pg_wal))
        xlog_is_symlink = true;
#endif

    /*
     * If possible, hint to the kernel that we're soon going to fsync the data
     * directory and its contents.
     */
#ifdef PG_FLUSH_DATA_WORKS
    walkdir(pg_data, pre_sync_fname, false);
    if (xlog_is_symlink)
        walkdir(pg_wal, pre_sync_fname, false);
    walkdir(pg_tblspc, pre_sync_fname, true);
#endif

    /*
     * Now we do the fsync()s in the same order.
     *
     * The main call ignores symlinks, so in addition to specially processing
     * pg_wal if it's a symlink, pg_tblspc has to be visited separately with
     * process_symlinks = true.  Note that if there are any plain directories
     * in pg_tblspc, they'll 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_wal, fsync_fname, false);
    walkdir(pg_tblspc, fsync_fname, true);
}