diff mbox series

[v2,7/9] reftable/stack: use lock_file when adding table to "tables.list"

Message ID b868a518d67eb1566f102a94cf2c0fd45fa2668b.1722862822.git.ps@pks.im (mailing list archive)
State Accepted
Commit 128b9aa3e9d3dc0417f8f65a240aad736db97959
Headers show
Series reftable: improvements and fixes for compaction | expand

Commit Message

Patrick Steinhardt Aug. 5, 2024, 1:08 p.m. UTC
When modifying "tables.list", we need to lock the list before updating
it to ensure that no concurrent writers modify the list at the same
point in time. While we do this via the `lock_file` subsystem when
compacting the stack, we manually handle the lock when adding a new
table to it. While not wrong, it is at least inconsistent.

Refactor the code to consistently lock "tables.list" via the `lock_file`
subsytem.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
---
 reftable/stack.c | 21 +++++++++++----------
 1 file changed, 11 insertions(+), 10 deletions(-)
diff mbox series

Patch

diff --git a/reftable/stack.c b/reftable/stack.c
index 9ca549294f..54982e0f7d 100644
--- a/reftable/stack.c
+++ b/reftable/stack.c
@@ -567,7 +567,7 @@  static void format_name(struct strbuf *dest, uint64_t min, uint64_t max)
 }
 
 struct reftable_addition {
-	struct tempfile *lock_file;
+	struct lock_file tables_list_lock;
 	struct reftable_stack *stack;
 
 	char **new_tables;
@@ -581,13 +581,13 @@  static int reftable_stack_init_addition(struct reftable_addition *add,
 					struct reftable_stack *st)
 {
 	struct strbuf lock_file_name = STRBUF_INIT;
-	int err = 0;
-	add->stack = st;
+	int err;
 
-	strbuf_addf(&lock_file_name, "%s.lock", st->list_file);
+	add->stack = st;
 
-	add->lock_file = create_tempfile(lock_file_name.buf);
-	if (!add->lock_file) {
+	err = hold_lock_file_for_update(&add->tables_list_lock, st->list_file,
+					LOCK_NO_DEREF);
+	if (err < 0) {
 		if (errno == EEXIST) {
 			err = REFTABLE_LOCK_ERROR;
 		} else {
@@ -596,7 +596,8 @@  static int reftable_stack_init_addition(struct reftable_addition *add,
 		goto done;
 	}
 	if (st->opts.default_permissions) {
-		if (chmod(add->lock_file->filename.buf, st->opts.default_permissions) < 0) {
+		if (chmod(get_lock_file_path(&add->tables_list_lock),
+			  st->opts.default_permissions) < 0) {
 			err = REFTABLE_IO_ERROR;
 			goto done;
 		}
@@ -635,7 +636,7 @@  static void reftable_addition_close(struct reftable_addition *add)
 	add->new_tables_len = 0;
 	add->new_tables_cap = 0;
 
-	delete_tempfile(&add->lock_file);
+	rollback_lock_file(&add->tables_list_lock);
 	strbuf_release(&nm);
 }
 
@@ -651,7 +652,7 @@  void reftable_addition_destroy(struct reftable_addition *add)
 int reftable_addition_commit(struct reftable_addition *add)
 {
 	struct strbuf table_list = STRBUF_INIT;
-	int lock_file_fd = get_tempfile_fd(add->lock_file);
+	int lock_file_fd = get_lock_file_fd(&add->tables_list_lock);
 	int err = 0;
 	size_t i;
 
@@ -680,7 +681,7 @@  int reftable_addition_commit(struct reftable_addition *add)
 		goto done;
 	}
 
-	err = rename_tempfile(&add->lock_file, add->stack->list_file);
+	err = commit_lock_file(&add->tables_list_lock);
 	if (err < 0) {
 		err = REFTABLE_IO_ERROR;
 		goto done;