Re: [PATCH] Fix losing locks during fork

From: Pavel Shilovsky <[email protected]>

When process does fork() private_data of files with lock list stays the same
for file descriptors of the parent and of the child. While finishing the child closes
files and deletes locks from the list even if unlocking fails. When the child process
finishes the parent doesn't have lock in lock list and can't unlock previously before
fork() locked region after the child process finished.

This patch provides behaviour to save locks in lock list if unlocking fails.

Signed-off-by: Pavel Shilovsky <[email protected]>
Reviewed-by: Jeff Layton <[email protected]>
---
 fs/cifs/file.c |    7 ++++---
 1 files changed, 4 insertions(+), 3 deletions(-)

diff --git a/fs/cifs/file.c b/fs/cifs/file.c
index c34b7f8..7185cd3 100644
--- a/fs/cifs/file.c
+++ b/fs/cifs/file.c
@@ -898,9 +898,10 @@ int cifs_lock(struct file *file, int cmd, struct file_lock *pfLock)
                                                        1, 0, li->type, false);
                                        if (stored_rc)
                                                rc = stored_rc;
-
-                                       list_del(&li->llist);
-                                       kfree(li);
+                                       else {
+                                               list_del(&li->llist);
+                                               kfree(li);
+                                       }
                                }
                        }
                        mutex_unlock(&fid->lock_mutex);
-- 
1.6.6.1