nfsdcld: use WAL journal for faster commits

Commit Message

J. Bruce Fields Jan. 4, 2022, 10:24 p.m. UTC

From: "J. Bruce Fields" <[e-mail]>

Currently nfsdcld is doing three fdatasyncs for each upcall.  Based on
SQLite documentation, WAL mode should also be safe, and I can confirm
from an strace that it results in only one fdatasync each.

This may be a bottleneck e.g. when lots of clients are being created or
expired at once (e.g. on reboot).

Not bothering with error checking, as this is just an optimization and
nfsdcld will still function without.  (Might be better to log something
on failure, though.)

Reviewed-by: Chuck Lever <[e-mail]>
Signed-off-by: J. Bruce Fields <[e-mail]>
---
 aclocal/libsqlite3.m4  | 2 +-
 utils/nfsdcld/sqlite.c | 2 ++
 2 files changed, 3 insertions(+), 1 deletion(-)

Resending to make sure SteveD saw this....--b.

Patch

diff --git a/aclocal/libsqlite3.m4 b/aclocal/libsqlite3.m4
index 8c38993cbba8..c3beb4d56f0c 100644
--- a/aclocal/libsqlite3.m4
+++ b/aclocal/libsqlite3.m4
@@ -22,7 +22,7 @@  AC_DEFUN([AC_SQLITE3_VERS], [
 		int vers = sqlite3_libversion_number();
 
 		return vers != SQLITE_VERSION_NUMBER ||
-			vers < 3003000;
+			vers < 3007000;
 	}
        ], [libsqlite3_cv_is_recent=yes], [libsqlite3_cv_is_recent=no],
        [libsqlite3_cv_is_recent=unknown])
diff --git a/utils/nfsdcld/sqlite.c b/utils/nfsdcld/sqlite.c
index 03016fb95823..eabb0daa95f5 100644
--- a/utils/nfsdcld/sqlite.c
+++ b/utils/nfsdcld/sqlite.c
@@ -826,6 +826,8 @@  sqlite_prepare_dbh(const char *topdir)
 		goto out_close;
 	}
 
+	sqlite3_exec(dbh, "PRAGMA journal_mode = WAL;", NULL, NULL, NULL);
+
 	ret = sqlite_query_schema_version();
 	switch (ret) {
 	case CLD_SQLITE_LATEST_SCHEMA_VERSION: