Fix bug #8175 - smbd deadlock.

[metze/samba/wip.git] / source3 / smbd / open.c

diff --git a/source3/smbd/open.c b/source3/smbd/open.c
index bb7e6c29dfa495b189609f0aad5fc1553deacab2..5c9288066850757e2ae17935e66f3d35f0c73514 100644 (file)
--- a/source3/smbd/open.c
+++ b/source3/smbd/open.c
@@ -1055,18 +1055,8 @@ static bool delay_for_exclusive_oplocks(files_struct *fsp,
        return false;
 }
 
-static bool file_has_brlocks(files_struct *fsp)
-{
-       struct byte_range_lock *br_lck;
-
-       br_lck = brl_get_locks_readonly(fsp);
-       if (!br_lck)
-               return false;
-
-       return br_lck->num_locks > 0 ? true : false;
-}
-
 static void grant_fsp_oplock_type(files_struct *fsp,
+                               const struct byte_range_lock *br_lck,
                                int oplock_request,
                                bool got_level2_oplock,
                                bool got_a_none_oplock)
@@ -1084,7 +1074,7 @@ static void grant_fsp_oplock_type(files_struct *fsp,
                DEBUG(10,("grant_fsp_oplock_type: oplock type 0x%x on file %s\n",
                        fsp->oplock_type, fsp_str_dbg(fsp)));
                return;
-       } else if (lp_locking(fsp->conn->params) && file_has_brlocks(fsp)) {
+       } else if (br_lck && br_lck->num_locks > 0) {
                DEBUG(10,("grant_fsp_oplock_type: file %s has byte range locks\n",
                        fsp_str_dbg(fsp)));
                fsp->oplock_type = NO_OPLOCK;
@@ -1562,6 +1552,55 @@ void remove_deferred_open_entry(struct file_id id, uint64_t mid,
        }
 }
 
+/****************************************************************
+ Ensure we get the brlock lock followed by the share mode lock
+ in the correct order to prevent deadlocks if other smbd's are
+ using the brlock database on this file simultaneously with this open
+ (that code also gets the locks in brlock -> share mode lock order).
+****************************************************************/
+
+static bool acquire_ordered_locks(TALLOC_CTX *mem_ctx,
+                               files_struct *fsp,
+                               const struct file_id id,
+                               const char *connectpath,
+                               const struct smb_filename *smb_fname,
+                               const struct timespec *p_old_write_time,
+                               struct share_mode_lock **p_lck,
+                               struct byte_range_lock **p_br_lck)
+{
+       /* Ordering - we must get the br_lck for this
+          file before the share mode. */
+       if (lp_locking(fsp->conn->params)) {
+               *p_br_lck = brl_get_locks_readonly(fsp);
+               if (*p_br_lck == NULL) {
+                       DEBUG(0, ("Could not get br_lock\n"));
+                       return false;
+               }
+               /* Note - we don't need to free the returned
+                  br_lck explicitly as it was allocated on talloc_tos()
+                  and so will be autofreed (and release the lock)
+                  once the frame context disappears.
+
+                  If it was set to fsp->brlock_rec then it was
+                  talloc_move'd to hang off the fsp pointer and
+                  in this case is guarenteed to not be holding the
+                  lock on the brlock database. */
+       }
+
+       *p_lck = get_share_mode_lock(mem_ctx,
+                               id,
+                               connectpath,
+                               smb_fname,
+                               p_old_write_time);
+
+       if (*p_lck == NULL) {
+               DEBUG(0, ("Could not get share mode lock\n"));
+               TALLOC_FREE(*p_br_lck);
+               return false;
+       }
+       return true;
+}
+
 /****************************************************************************
  Open a file with a share mode. Passed in an already created files_struct *.
 ****************************************************************************/
@@ -1906,6 +1945,7 @@ static NTSTATUS open_file_ntcreate(connection_struct *conn,
        }
 
        if (file_existed) {
+               struct byte_range_lock *br_lck = NULL;
                struct share_mode_entry *batch_entry = NULL;
                struct share_mode_entry *exclusive_entry = NULL;
                bool got_level2_oplock = false;
@@ -1914,12 +1954,14 @@ static NTSTATUS open_file_ntcreate(connection_struct *conn,
                struct timespec old_write_time = smb_fname->st.st_ex_mtime;
                id = vfs_file_id_from_sbuf(conn, &smb_fname->st);
 
-               lck = get_share_mode_lock(talloc_tos(), id,
-                                         conn->connectpath,
-                                         smb_fname, &old_write_time);
-
-               if (lck == NULL) {
-                       DEBUG(0, ("Could not get share mode lock\n"));
+               if (!acquire_ordered_locks(talloc_tos(),
+                                       fsp,
+                                       id,
+                                       conn->connectpath,
+                                       smb_fname,
+                                       &old_write_time,
+                                       &lck,
+                                       &br_lck)) {
                        return NT_STATUS_SHARING_VIOLATION;
                }
 
@@ -1973,6 +2015,7 @@ static NTSTATUS open_file_ntcreate(connection_struct *conn,
                }
 
                grant_fsp_oplock_type(fsp,
+                               br_lck,
                                 oplock_request,
                                 got_level2_oplock,
                                 got_a_none_oplock);
@@ -2136,6 +2179,7 @@ static NTSTATUS open_file_ntcreate(connection_struct *conn,
        }
 
        if (!file_existed) {
+               struct byte_range_lock *br_lck = NULL;
                struct share_mode_entry *batch_entry = NULL;
                struct share_mode_entry *exclusive_entry = NULL;
                bool got_level2_oplock = false;
@@ -2158,15 +2202,14 @@ static NTSTATUS open_file_ntcreate(connection_struct *conn,
 
                id = fsp->file_id;
 
-               lck = get_share_mode_lock(talloc_tos(), id,
-                                         conn->connectpath,
-                                         smb_fname, &old_write_time);
-
-               if (lck == NULL) {
-                       DEBUG(0, ("open_file_ntcreate: Could not get share "
-                                 "mode lock for %s\n",
-                                 smb_fname_str_dbg(smb_fname)));
-                       fd_close(fsp);
+               if (!acquire_ordered_locks(talloc_tos(),
+                                       fsp,
+                                       id,
+                                       conn->connectpath,
+                                       smb_fname,
+                                       &old_write_time,
+                                       &lck,
+                                       &br_lck)) {
                        return NT_STATUS_SHARING_VIOLATION;
                }
 
@@ -2237,6 +2280,7 @@ static NTSTATUS open_file_ntcreate(connection_struct *conn,
                }
 
                grant_fsp_oplock_type(fsp,
+                               br_lck,
                                 oplock_request,
                                 got_level2_oplock,
                                 got_a_none_oplock);