fs_inode:Change the type of i_crefs to atomic_int

Summary:
  1.Modified the i_crefs from int16_t to atomic_int
  2.Modified the i_crefs add, delete, read, and initialize interfaces to atomic operations
The purpose of this change is to avoid deadlock in cross-core scenarios, where A Core blocks B Core’s request for a write operation to A Core when A Core requests a read operation to B Core.

Signed-off-by: chenrun1 <chenrun1@xiaomi.com>

fs/inode/fs_inodeaddref.c

@@ -47,12 +47,7 @@ int inode_addref(FAR struct inode *inode)
 
   if (inode)
     {
-      ret = inode_lock();
-      if (ret >= 0)
-        {
-          inode->i_crefs++;
-          inode_unlock();
-        }
+      atomic_fetch_add(&inode->i_crefs, 1);
     }
 
   return ret;

fs/inode/fs_inodefind.c

@@ -71,7 +71,7 @@ int inode_find(FAR struct inode_search_s *desc)
 
       /* Increment the reference count on the inode */
 
-      node->i_crefs++;
+      atomic_fetch_add(&node->i_crefs, 1);
     }
 
   inode_unlock();

fs/inode/fs_inoderelease.c

@@ -53,43 +53,10 @@ void inode_release(FAR struct inode *inode)
     {
       /* Decrement the references of the inode */
 
-      do
+      if (atomic_fetch_sub(&inode->i_crefs, 1) <= 1)
         {
-          ret = inode_lock();
-
-          /* This only possible error is due to cancellation of the thread.
-           * We need to try again anyway in this case, otherwise the
-           * reference count would be wrong.
-           */
-
-          DEBUGASSERT(ret == OK || ret == -ECANCELED);
-        }
-      while (ret < 0);
-
-      if (inode->i_crefs)
-        {
-          inode->i_crefs--;
-        }
-
-      /* If the subtree was previously deleted and the reference
-       * count has decrement to zero,  then delete the inode
-       * now.
-       */
-
-      if (inode->i_crefs <= 0)
-        {
-          /* If the inode has been properly unlinked, then the peer pointer
-           * should be NULL.
-           */
-
-          inode_unlock();
-
           DEBUGASSERT(inode->i_peer == NULL);
           inode_free(inode);
         }
-      else
-        {
-          inode_unlock();
-        }
     }
 }

fs/inode/fs_inoderemove.c

@@ -96,7 +96,7 @@ static FAR struct inode *inode_unlink(FAR const char *path)
 
       node->i_peer   = NULL;
       node->i_parent = NULL;
-      node->i_crefs--;
+      atomic_fetch_sub(&node->i_crefs, 1);
     }
 
   RELEASE_SEARCH(&desc);
@@ -134,7 +134,7 @@ int inode_remove(FAR const char *path)
        * to it
        */
 
-      if (node->i_crefs)
+      if (atomic_load(&inode->i_crefs))
         {
           return -EBUSY;
         }

fs/inode/fs_inodereserve.c

@@ -85,7 +85,7 @@ static FAR struct inode *inode_alloc(FAR const char *name, mode_t mode)
   if (node)
     {
       node->i_ino   = g_ino++;
-      node->i_crefs = 1;
+      atomic_init(&node->i_crefs, 1);
 #ifdef CONFIG_PSEUDOFS_ATTRIBUTES
       node->i_mode  = mode;
       clock_gettime(CLOCK_REALTIME, &node->i_atime);

fs/mount/fs_mount.c

@@ -438,7 +438,7 @@ int nx_mount(FAR const char *source, FAR const char *target,
   if (drvr_inode != NULL)
 #endif
     {
-      drvr_inode->i_crefs++;
+      atomic_fetch_add(&drvr_inode->i_crefs, 1);
     }
 #endif
 
@@ -466,7 +466,7 @@ int nx_mount(FAR const char *source, FAR const char *target,
       if (drvr_inode != NULL)
 #endif
         {
-          drvr_inode->i_crefs--;
+          atomic_fetch_sub(&drvr_inode->i_crefs, 1);
         }
 #endif
 

fs/mount/fs_umount2.c

@@ -145,8 +145,7 @@ int nx_umount2(FAR const char *target, unsigned int flags)
     {
       /* Just decrement the reference count (without deleting it) */
 
-      DEBUGASSERT(mountpt_inode->i_crefs > 0);
-      mountpt_inode->i_crefs--;
+      atomic_fetch_sub(&mountpt_inode->i_crefs, 1);
       inode_unlock();
     }
   else

fs/mqueue/mq_open.c

@@ -74,7 +74,7 @@ static int nxmq_file_close(FAR struct file *filep)
 {
   FAR struct inode *inode = filep->f_inode;
 
-  if (inode->i_crefs <= 0)
+  if (atomic_load(&inode->i_crefs) <= 0)
     {
       FAR struct mqueue_inode_s *msgq = inode->i_private;
 
@@ -322,7 +322,7 @@ static int file_mq_vopen(FAR struct file *mq, FAR const char *mq_name,
 
       /* Set the initial reference count on this inode to one */
 
-      inode->i_crefs++;
+      atomic_fetch_add(&inode->i_crefs, 1);
 
       if (created)
         {

fs/mqueue/mq_unlink.c

@@ -56,7 +56,7 @@
 
 static void mq_inode_release(FAR struct inode *inode)
 {
-  if (inode->i_crefs <= 1)
+  if (atomic_load(&inode->i_crefs) <= 1)
     {
       FAR struct mqueue_inode_s *msgq = inode->i_private;
 

fs/semaphore/sem_close.c

@@ -81,42 +81,20 @@ int nxsem_close(FAR sem_t *sem)
   DEBUGASSERT(nsem->ns_inode);
   inode = nsem->ns_inode;
 
-  /* Decrement the reference count on the inode */
-
-  do
-    {
-      ret = inode_lock();
-
-      /* The only error that is expected is due to thread cancellation.
-       * At this point, we must continue to free the semaphore anyway.
-       */
-
-      DEBUGASSERT(ret == OK || ret == -ECANCELED);
-    }
-  while (ret < 0);
-
-  if (inode->i_crefs > 0)
-    {
-      inode->i_crefs--;
-    }
-
   /* If the semaphore was previously unlinked and the reference count has
    * decremented to zero, then release the semaphore and delete the inode
    * now.
    */
 
-  if (inode->i_crefs <= 0)
+  if (atomic_fetch_sub(&inode->i_crefs, 1) <= 1)
     {
-      /* Destroy the semaphore and free the container */
-
       nxsem_destroy(&nsem->ns_sem);
       group_free(NULL, nsem);
 
       /* Release and free the inode container.  If it has been properly
        * unlinked, then the peer pointer should be NULL.
        */
 
-      inode_unlock();
 #ifdef CONFIG_FS_NOTIFY
       notify_close2(inode);
 #endif
@@ -125,7 +103,6 @@ int nxsem_close(FAR sem_t *sem)
       return OK;
     }
 
-  inode_unlock();
   return OK;
 }
 

fs/semaphore/sem_open.c

@@ -211,7 +211,7 @@ int nxsem_open(FAR sem_t **sem, FAR const char *name, int oflags, ...)
       /* Initialize the inode */
 
       INODE_SET_NAMEDSEM(inode);
-      inode->i_crefs++;
+      atomic_fetch_add(&inode->i_crefs, 1);
 
       /* Initialize the semaphore */
 

fs/shm/shm_open.c

@@ -137,7 +137,7 @@ static int file_shm_open(FAR struct file *shm, FAR const char *name,
       INODE_SET_SHM(inode);
       inode->u.i_ops = &g_shmfs_operations;
       inode->i_private = NULL;
-      inode->i_crefs++;
+      atomic_fetch_add(&inode->i_crefs, 1);
     }
 
   /* Associate the inode with a file structure */

fs/shm/shmfs.c

@@ -185,21 +185,15 @@ static int shmfs_release(FAR struct inode *inode)
    * The inode is released after this call, hence checking if i_crefs <= 1.
    */
 
-  int ret = inode_lock();
-  if (ret >= 0)
+  inode_lock();
+  if (inode->i_parent == NULL && atomic_load(&inode->i_crefs) <= 1)
     {
-      if (inode->i_parent == NULL &&
-          inode->i_crefs <= 1)
-        {
-          shmfs_free_object(inode->i_private);
-          inode->i_private = NULL;
-          ret = OK;
-        }
-
-      inode_unlock();
+      shmfs_free_object(inode->i_private);
+      inode->i_private = NULL;
     }
 
-  return ret;
+  inode_unlock();
+  return OK;
 }
 
 /****************************************************************************
@@ -267,20 +261,15 @@ static int shmfs_truncate(FAR struct file *filep, off_t length)
 #ifndef CONFIG_DISABLE_PSEUDOFS_OPERATIONS
 static int shmfs_unlink(FAR struct inode *inode)
 {
-  int ret = inode_lock();
-
-  if (ret >= 0)
+  inode_lock();
+  if (atomic_load(&inode->i_crefs) <= 1)
     {
-      if (inode->i_crefs <= 1)
-        {
-          shmfs_free_object(inode->i_private);
-          inode->i_private = NULL;
-        }
-
-      inode_unlock();
+      shmfs_free_object(inode->i_private);
+      inode->i_private = NULL;
     }
 
-  return ret;
+  inode_unlock();
+  return OK;
 }
 #endif
 

fs/socket/socket.c

@@ -75,7 +75,7 @@ static struct inode g_sock_inode =
   NULL,                   /* i_parent */
   NULL,                   /* i_peer */
   NULL,                   /* i_child */
-  1,                      /* i_crefs */
+  ATOMIC_VAR_INIT(1),     /* i_crefs */
   FSNODEFLAG_TYPE_SOCKET, /* i_flags */
   {
     &g_sock_fileops       /* u */

fs/vfs/fs_dir.c

@@ -216,7 +216,7 @@ static off_t seek_pseudodir(FAR struct file *filep, off_t offset)
     {
       /* Increment the reference count on this next node */
 
-      curr->i_crefs++;
+      atomic_fetch_add(&curr->i_crefs, 1);
     }
 
   inode_unlock();
@@ -383,7 +383,7 @@ static int read_pseudodir(FAR struct fs_dirent_s *dir,
     {
       /* Increment the reference count on this next node */
 
-      pdir->next->i_crefs++;
+      atomic_fetch_add(&pdir->next->i_crefs, 1);
     }
 
   inode_unlock();

fs/vfs/fs_epoll.c

@@ -123,7 +123,7 @@ static struct inode g_epoll_inode =
   NULL,                   /* i_parent */
   NULL,                   /* i_peer */
   NULL,                   /* i_child */
-  1,                      /* i_crefs */
+  ATOMIC_VAR_INIT(1),     /* i_crefs */
   FSNODEFLAG_TYPE_DRIVER, /* i_flags */
   {
     &g_epoll_ops          /* u */

fs/vfs/fs_eventfd.c

@@ -112,7 +112,7 @@ static struct inode g_eventfd_inode =
   NULL,                   /* i_parent */
   NULL,                   /* i_peer */
   NULL,                   /* i_child */
-  1,                      /* i_crefs */
+  ATOMIC_VAR_INIT(1),     /* i_crefs */
   FSNODEFLAG_TYPE_DRIVER, /* i_flags */
   {
     &g_eventfd_fops       /* u */

fs/vfs/fs_pseudofile.c

@@ -353,26 +353,23 @@ static int pseudofile_munmap(FAR struct task_group_s *group,
    * The inode is released after this call, hence checking if i_crefs <= 1.
    */
 
-  int ret = inode_lock();
-  if (ret >= 0)
+  inode_lock();
+  if (inode->i_parent == NULL &&
+      atomic_load(&inode->i_crefs) <= 1)
     {
-      if (inode->i_parent == NULL &&
-          inode->i_crefs <= 1)
-        {
-          /* Delete the inode metadata */
+      /* Delete the inode metadata */
 
-          if (inode->i_private)
-            {
-              fs_heap_free(inode->i_private);
-            }
-
-          inode->i_private = NULL;
-          ret = OK;
+      if (inode->i_private)
+        {
+          fs_heap_free(inode->i_private);
         }
 
-      inode_unlock();
+      inode->i_private = NULL;
+      ret = OK;
     }
 
+  inode_unlock();
+
   /* Unkeep the inode when unmapped, decrease refcount */
 
   if (ret == OK)
@@ -501,7 +498,6 @@ int pseudofile_create(FAR struct inode **node, FAR const char *path,
       goto reserve_err;
     }
 
-  (*node)->i_crefs = 0;
   (*node)->i_flags = 1;
   (*node)->u.i_ops = &g_pseudofile_ops;
   (*node)->i_private = pf;

fs/vfs/fs_signalfd.c

@@ -89,7 +89,7 @@ static struct inode g_signalfd_inode =
   NULL,                   /* i_parent */
   NULL,                   /* i_peer */
   NULL,                   /* i_child */
-  1,                      /* i_crefs */
+  ATOMIC_VAR_INIT(1),     /* i_crefs */
   FSNODEFLAG_TYPE_DRIVER, /* i_flags */
   {
     &g_signalfd_fileops   /* u */

fs/vfs/fs_timerfd.c

@@ -123,7 +123,7 @@ static struct inode g_timerfd_inode =
   NULL,                   /* i_parent */
   NULL,                   /* i_peer */
   NULL,                   /* i_child */
-  1,                      /* i_crefs */
+  ATOMIC_VAR_INIT(1),     /* i_crefs */
   FSNODEFLAG_TYPE_DRIVER, /* i_flags */
   {
     &g_timerfd_fops       /* u */