[linux-cifs-client] [PATCH] Fix losing locks during fork

[Pavel Shilovsky]

From: Pavel Shilovsky <piastryyy at gmail.com>

When process does fork() private_data of files with lock list stays the same
for file descriptors of the parent and of the child. That's why the parent can't unlock
previously before fork() locked region after the child process finished. 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.
---
 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

--
Best regards,
Pavel Shilovsky.