smbd: Add file_has_read_lease()

This caches share_mode_data->flags in the fsp, cache flush happening
on tdb_seqnum change.

Signed-off-by: Volker Lendecke <vl@samba.org>
Reviewed-by: Ralph Boehme <slow@samba.org>

3 files changed, 73 insertions, 1 deletions

diff --git a/source3/include/vfs.h b/source3/include/vfs.h
index a7ac50f06d2..4c778839880 100644
--- a/source3/include/vfs.h
+++ b/source3/include/vfs.h
@@ -375,6 +375,12 @@ typedef struct files_struct {
 	struct files_struct *base_fsp; /* placeholder for delete on close */
 
 	/*
+	 * Cache of share_mode_data->flags
+	 */
+	int share_mode_flags_seqnum;
+	uint8_t share_mode_flags;
+
+	/*
 	 * Read-only cached brlock record, thrown away when the
 	 * brlock.tdb seqnum changes. This avoids fetching data from
 	 * the brlock.tdb on every read/write call.
diff --git a/source3/locking/proto.h b/source3/locking/proto.h
index 604d66ebd3a..a1c6529183a 100644
--- a/source3/locking/proto.h
+++ b/source3/locking/proto.h
@@ -126,6 +126,8 @@ struct share_mode_lock *get_share_mode_lock(
 	const struct smb_filename *smb_fname,
 	const struct timespec *old_write_time);
 
+bool file_has_read_lease(struct files_struct *fsp);
+
 struct db_record;
 NTSTATUS share_mode_do_locked(
 	struct file_id id,
diff --git a/source3/locking/share_mode_lock.c b/source3/locking/share_mode_lock.c
index 79a0580118f..430d14fab4a 100644
--- a/source3/locking/share_mode_lock.c
+++ b/source3/locking/share_mode_lock.c
@@ -77,7 +77,11 @@ static bool locking_init_internal(bool read_only)
 
 	backend = db_open(NULL, db_path,
 			  SMB_OPEN_DATABASE_TDB_HASH_SIZE,
-			  TDB_DEFAULT|TDB_VOLATILE|TDB_CLEAR_IF_FIRST|TDB_INCOMPATIBLE_HASH,
+			  TDB_DEFAULT|
+			  TDB_VOLATILE|
+			  TDB_CLEAR_IF_FIRST|
+			  TDB_INCOMPATIBLE_HASH|
+			  TDB_SEQNUM,
 			  read_only?O_RDONLY:O_RDWR|O_CREAT, 0644,
 			  DBWRAP_LOCK_ORDER_1, DBWRAP_FLAG_NONE);
 	TALLOC_FREE(db_path);
@@ -191,6 +195,66 @@ static enum ndr_err_code get_share_mode_blob_header(
 	return NDR_ERR_SUCCESS;
 }
 
+struct fsp_update_share_mode_flags_state {
+	enum ndr_err_code ndr_err;
+	uint8_t share_mode_flags;
+};
+
+static void fsp_update_share_mode_flags_fn(
+	struct db_record *rec, bool *modified_dependent, void *private_data)
+{
+	struct fsp_update_share_mode_flags_state *state = private_data;
+	TDB_DATA value = dbwrap_record_get_value(rec);
+	DATA_BLOB blob = { .data = value.dptr, .length = value.dsize };
+	uint64_t seq;
+
+	state->ndr_err = get_share_mode_blob_header(
+		&blob, &seq, &state->share_mode_flags);
+}
+
+static NTSTATUS fsp_update_share_mode_flags(struct files_struct *fsp)
+{
+	struct fsp_update_share_mode_flags_state state = {0};
+	int seqnum = dbwrap_get_seqnum(lock_db);
+	NTSTATUS status;
+
+	if (seqnum == fsp->share_mode_flags_seqnum) {
+		return NT_STATUS_OK;
+	}
+
+	status = share_mode_do_locked(
+		fsp->file_id, fsp_update_share_mode_flags_fn, &state);
+	if (!NT_STATUS_IS_OK(status)) {
+		DBG_DEBUG("share_mode_do_locked returned %s\n",
+			  nt_errstr(status));
+		return status;
+	}
+
+	if (!NDR_ERR_CODE_IS_SUCCESS(state.ndr_err)) {
+		DBG_DEBUG("get_share_mode_blob_header returned %s\n",
+			  ndr_errstr(state.ndr_err));
+		return ndr_map_error2ntstatus(state.ndr_err);
+	}
+
+	fsp->share_mode_flags_seqnum = seqnum;
+	fsp->share_mode_flags = state.share_mode_flags;
+
+	return NT_STATUS_OK;
+}
+
+bool file_has_read_lease(struct files_struct *fsp)
+{
+	NTSTATUS status;
+
+	status = fsp_update_share_mode_flags(fsp);
+	if (!NT_STATUS_IS_OK(status)) {
+		/* Safe default for leases */
+		return true;
+	}
+
+	return (fsp->share_mode_flags & SHARE_MODE_HAS_READ_LEASE) != 0;
+}
+
 static int share_mode_data_nofree_destructor(struct share_mode_data *d)
 {
 	return -1;