[PATCH v3 14/20] insert: fsync new directory after rename

[Peter Wang]

After moving the file from the 'tmp' to the 'new' directory,
fsync on the 'new' directory for durability.
---
 notmuch-insert.c | 41 ++++++++++++++++++++++++++++++++++-------
 1 file changed, 34 insertions(+), 7 deletions(-)

diff --git a/notmuch-insert.c b/notmuch-insert.c
index 60855c1..c4d5e75 100644
--- a/notmuch-insert.c
+++ b/notmuch-insert.c
@@ -56,6 +56,28 @@ check_folder_name (const char *folder)
     }
 }

+/* Call fsync() on a directory path. */
+static notmuch_bool_t
+sync_dir (const char *dir)
+{
+    notmuch_bool_t ret;
+    int fd;
+
+    ret = TRUE;
+    fd = open (dir, O_RDONLY);
+    if (fd == -1) {
+       fprintf (stderr, "Error: open() dir failed: %s\n", strerror (errno));
+       ret = FALSE;
+    }
+    if (ret && fsync (fd) != 0) {
+       fprintf (stderr, "Error: fsync() dir failed: %s\n", strerror (errno));
+       ret = FALSE;
+    }
+    if (fd != -1)
+       close (fd);
+    return ret;
+}
+
 /* Make the given directory, succeeding if it already exists. */
 static notmuch_bool_t
 make_directory (char *path, int mode)
@@ -140,10 +162,11 @@ maildir_create_folder (void *ctx, const char *dir)
 /* Open a unique file in the Maildir 'tmp' directory.
  * Returns the file descriptor on success, or -1 on failure.
  * On success, file paths for the message in the 'tmp' and 'new'
- * directories are returned via tmppath and newpath. */
+ * directories are returned via tmppath and newpath,
+ * and the path of the 'new' directory itself in newdir. */
 static int
 maildir_open_tmp_file (void *ctx, const char *dir,
-                      char **tmppath, char **newpath)
+                      char **tmppath, char **newpath, char **newdir)
 {
     pid_t pid;
     char hostname[256];
@@ -180,8 +203,9 @@ maildir_open_tmp_file (void *ctx, const char *dir,
        return -1;
     }

+    *newdir = talloc_asprintf (ctx, "%s/new", dir);
     *newpath = talloc_asprintf (ctx, "%s/new/%s", dir, filename);
-    if (! *newpath) {
+    if (! *newdir || ! *newpath) {
        fprintf (stderr, "Out of memory\n");
        close (fd);
        unlink (*tmppath);
@@ -201,14 +225,16 @@ maildir_open_tmp_file (void *ctx, const char *dir,
  * http://wiki.dovecot.org/MailboxFormat/Maildir#Mail_delivery
  */
 static notmuch_bool_t
-maildir_move_tmp_to_new (const char *tmppath, const char *newpath)
+maildir_move_tmp_to_new (const char *tmppath, const char *newpath,
+                        const char *newdir)
 {
     if (rename (tmppath, newpath) != 0) {
        fprintf (stderr, "Error: rename() failed: %s\n", strerror (errno));
        return FALSE;
     }

-    return TRUE;
+    /* Sync the 'new' directory after rename for durability. */
+    return sync_dir (newdir);
 }

 /* Copy the contents of standard input (fdin) into fdout. */
@@ -297,10 +323,11 @@ insert_message (void *ctx, notmuch_database_t *notmuch, 
int fdin,
 {
     char *tmppath;
     char *newpath;
+    char *newdir;
     int fdout;
     notmuch_bool_t ret;

-    fdout = maildir_open_tmp_file (ctx, dir, &tmppath, &newpath);
+    fdout = maildir_open_tmp_file (ctx, dir, &tmppath, &newpath, &newdir);
     if (fdout < 0) {
        return FALSE;
     }
@@ -311,7 +338,7 @@ insert_message (void *ctx, notmuch_database_t *notmuch, int 
fdin,
     }
     close (fdout);
     if (ret) {
-       ret = maildir_move_tmp_to_new (tmppath, newpath);
+       ret = maildir_move_tmp_to_new (tmppath, newpath, newdir);
     }
     if (!ret) {
        unlink (tmppath);
-- 
1.7.12.1