From: Volker Lendecke <vl@samba.org>
Date: Mon, 1 Jul 2019 13:56:27 +0000 (+0200)
Subject: smbd: Send do_lock() through share_mode_do_locked()
X-Git-Tag: samba-4.11.0rc1~103
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=c5659f7b05289d23efe0288702157c6b5442ed3d;p=thirdparty%2Fsamba.git

smbd: Send do_lock() through share_mode_do_locked()

We need to maintain the locking hierarchy locking.tdb->brlock.tdb at
all times. vfs_fruit directly calls do_lock(), which might fail to
maintain the locking hierarchy: In brlock.c we call
contend_level2_oplocks_begin(), which will soon look at the
locking.tdb record.

For the SMB1 and SMB2 callers we already have the share mode locked,
we might want to watch that record for unlocks. For those callers
share_mode_do_locked() is practically free to call, we share the
underlying db_record.

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

diff --git a/source3/locking/locking.c b/source3/locking/locking.c
index 6c69b0055dc..86fd2ca1906 100644
--- a/source3/locking/locking.c
+++ b/source3/locking/locking.c
@@ -230,6 +230,47 @@ static void decrement_current_lock_count(files_struct *fsp,
  Utility function called by locking requests.
 ****************************************************************************/
 
+struct do_lock_state {
+	struct files_struct *fsp;
+	uint64_t smblctx;
+	uint64_t count;
+	uint64_t offset;
+	enum brl_type lock_type;
+	enum brl_flavour lock_flav;
+
+	struct server_id blocker_pid;
+	uint64_t blocker_smblctx;
+	NTSTATUS status;
+};
+
+static void do_lock_fn(
+	struct db_record *rec,
+	bool *modified_dependent,
+	void *private_data)
+{
+	struct do_lock_state *state = private_data;
+	struct byte_range_lock *br_lck = NULL;
+
+	br_lck = brl_get_locks(talloc_tos(), state->fsp);
+	if (br_lck == NULL) {
+		state->status = NT_STATUS_NO_MEMORY;
+		return;
+	}
+
+	state->status = brl_lock(
+		br_lck,
+		state->smblctx,
+		messaging_server_id(state->fsp->conn->sconn->msg_ctx),
+		state->offset,
+		state->count,
+		state->lock_type,
+		state->lock_flav,
+		&state->blocker_pid,
+		&state->blocker_smblctx);
+
+	TALLOC_FREE(br_lck);
+}
+
 NTSTATUS do_lock(files_struct *fsp,
 		 uint64_t smblctx,
 		 uint64_t count,
@@ -239,9 +280,14 @@ NTSTATUS do_lock(files_struct *fsp,
 		 struct server_id *pblocker_pid,
 		 uint64_t *psmblctx)
 {
-	struct byte_range_lock *br_lck = NULL;
-	struct server_id blocker_pid = { 0 };
-	uint64_t blocker_smblctx = 0;
+	struct do_lock_state state = {
+		.fsp = fsp,
+		.smblctx = smblctx,
+		.count = count,
+		.offset = offset,
+		.lock_type = lock_type,
+		.lock_flav = lock_flav,
+	};
 	NTSTATUS status;
 
 	/* silently return ok on print files as we don't do locking there */
@@ -271,36 +317,25 @@ NTSTATUS do_lock(files_struct *fsp,
 		  fsp_fnum_dbg(fsp),
 		  fsp_str_dbg(fsp));
 
-	br_lck = brl_get_locks(talloc_tos(), fsp);
-	if (!br_lck) {
-		return NT_STATUS_NO_MEMORY;
+	status = share_mode_do_locked(fsp->file_id, do_lock_fn, &state);
+	if (!NT_STATUS_IS_OK(status)) {
+		DBG_DEBUG("share_mode_do_locked returned %s\n",
+			  nt_errstr(status));
+		return status;
 	}
 
-	status = brl_lock(
-		br_lck,
-		smblctx,
-		messaging_server_id(fsp->conn->sconn->msg_ctx),
-		offset,
-		count,
-		lock_type,
-		lock_flav,
-		&blocker_pid,
-		&blocker_smblctx);
-
-	TALLOC_FREE(br_lck);
-
 	if (psmblctx != NULL) {
-		*psmblctx = blocker_smblctx;
+		*psmblctx = state.blocker_smblctx;
 	}
 	if (pblocker_pid != NULL) {
-		*pblocker_pid = blocker_pid;
+		*pblocker_pid = state.blocker_pid;
 	}
 
-	DBG_DEBUG("returning status=%s\n", nt_errstr(status));
+	DBG_DEBUG("returning status=%s\n", nt_errstr(state.status));
 
 	increment_current_lock_count(fsp, lock_flav);
 
-	return status;
+	return state.status;
 }
 
 /****************************************************************************