Remove unused filesys_lock in thread

src/threads/thread.c

@@ -736,7 +736,6 @@ static void init_thread(struct thread *t, const char *name, int priority) {
     /* Block process_wait of parent until this process is ready to die. */
     sema_init(&t->wait_sema, 0);
     sema_init(&t->done_sema, 1);
-    lock_init(&t->filesys_lock);
     t->loaded = false;
     t->waited_on = false;
     t->num_files = 0;

src/threads/thread.h

@@ -150,7 +150,6 @@ struct thread {
     struct semaphore exec_load;         /*!< Semaphore for checking when executable has loaded. */
     bool loaded;                        /*!< Check if exec loaded successfully. */
     struct file *executable;            /*!< Executable to keep open until done. */
-    struct lock filesys_lock;           /*!< Lock for filesys calls. */
     /**@}*/
 
 #ifdef USERPROG

src/userprog/DESIGNDOC

@@ -164,7 +164,6 @@ In our thread struct, we included these attributes and their following descripti
     struct semaphore exec_load;         /*!< Semaphore for checking when executable has loaded. */
     bool loaded;                        /*!< Check if exec loaded successfully. */
     struct file *executable;            /*!< Executable to keep open until done. */
-    struct lock filesys_lock;           /*!< Lock for filesys calls. */
     /**@}*/
 
 

src/userprog/syscall.c

@@ -158,13 +158,11 @@ void *get_third_arg(struct intr_frame *f) {
     static variables go out of memory. */
 void acquire_file_lock(void) {
     lock_acquire(&filesys_lock);
-    lock_acquire(&thread_current()->filesys_lock);
 }
 
 /*! Release file locks. See comment in acquire_file_lock. */
 void release_file_lock(void) {
     lock_release(&filesys_lock);
-    lock_release(&thread_current()->filesys_lock);
 }
 
 /*! Terminates Pintos. Should be seldom used due to loss of information on