locks: don't reuse file_lock in __posix_lock_file

Currently in the case where a new file lock completely replaces the old
one, we end up overwriting the existing lock with the new info. This
means that we have to call fl_release_private inside i_lock. Change the
code to instead copy the info to new_fl, insert that lock into the
correct spot and then delete the old lock. In a later patch, we'll defer
the freeing of the old lock until after the i_lock has been dropped.

Acked-by: J. Bruce Fields <bfields@fieldses.org>
Signed-off-by: Jeff Layton <jlayton@primarydata.com>

1 files changed, 14 insertions, 11 deletions

diff --git a/fs/locks.c b/fs/locks.c
index 2c2d4f5022a7..7dd4defb4d8d 100644
--- a/fs/locks.c
+++ b/fs/locks.c
@@ -1022,18 +1022,21 @@ static int __posix_lock_file(struct inode *inode, struct file_lock *request, str
                                         locks_delete_lock(before);
                                         continue;
                                 }
-                                /* Replace the old lock with the new one.
-                                 * Wake up anybody waiting for the old one,
-                                 * as the change in lock type might satisfy
-                                 * their needs.
+                                /*
+                                 * Replace the old lock with new_fl, and
+                                 * remove the old one. It's safe to do the
+                                 * insert here since we know that we won't be
+                                 * using new_fl later, and that the lock is
+                                 * just replacing an existing lock.
                                  */
-                                locks_wake_up_blocks(fl);
-                                fl->fl_start = request->fl_start;
-                                fl->fl_end = request->fl_end;
-                                fl->fl_type = request->fl_type;
-                                locks_release_private(fl);
-                                locks_copy_private(fl, request);
-                                request = fl;
+                                error = -ENOLCK;
+                                if (!new_fl)
+                                        goto out;
+                                locks_copy_lock(new_fl, request);
+                                request = new_fl;
+                                new_fl = NULL;
+                                locks_delete_lock(before);
+                                locks_insert_lock(before, request);
                                 added = true;
                         }
                 }