fs/unionfs: remove excessive protection to avoid deadlock

Deadlock during recursive access if unionfs overlays procfs,
check the critical segment only and remove the useless protection part.

|#0  unionfs_statfs (mountpt=0xf3df4540, buf=0xf3de2f0c) at unionfs/fs_unionfs.c:2136
...
|#6  0x08069429 in procfs_read (filep=0xf3df4574, buffer=0xf3df4610 "...", buflen=1024) at procfs/fs_procfs.c:412
|#7  0x0806c339 in unionfs_read (filep=0xf3de219c, buffer=0xf3df4610 "...", buflen=1024) at unionfs/fs_unionfs.c:1026

original call stack:
(gdb) bt
|#0  unionfs_statfs (mountpt=0xf3df4540, buf=0xf3de2f0c) at unionfs/fs_unionfs.c:2136
|#1  0x08071629 in mountpoint_filter (node=0xf3df4540, dirpath=0xf3df4a28 "/proc", arg=0xf3de2fc4) at mount/fs_foreachmountpoint.c:119
|#2  0x0807171b in foreach_inodelevel (node=0xf3df4540, info=0xf3df4a20) at inode/fs_foreachinode.c:90
|#3  0x08071898 in foreach_inode (handler=0x8071530 <mountpoint_filter>, arg=0xf3de2fc4) at inode/fs_foreachinode.c:193
|#4  0x080716c1 in foreach_mountpoint (handler=0x8070e2f <blocks_entry>, arg=0xf3de300c) at mount/fs_foreachmountpoint.c:169
|#5  0x08071399 in mount_read (filep=0xf3df4574, buffer=0xf3df4610 "...", buflen=1024) at mount/fs_procfs_mount.c:537
|#6  0x08069429 in procfs_read (filep=0xf3df4574, buffer=0xf3df4610 "...", buflen=1024) at procfs/fs_procfs.c:412
|#7  0x0806c339 in unionfs_read (filep=0xf3de219c, buffer=0xf3df4610 "...", buflen=1024) at unionfs/fs_unionfs.c:1026
|#8  0x080657a2 in file_read (filep=0xf3de219c, buf=0xf3df4610, nbytes=1024) at vfs/fs_read.c:110
|#9  0x0806581a in nx_read (fd=3, buf=0xf3df4610, nbytes=1024) at vfs/fs_read.c:175
|#10 0x08065847 in read (fd=3, buf=0xf3df4610, nbytes=1024) at vfs/fs_read.c:206
|#11 0x0805a242 in nsh_catfile (vtbl=0xf3df3f10, cmd=0xf3df4378 "df", filepath=0x808d5ed "/proc/fs/blocks") at nsh_fsutils.c:116
|#12 0x0805b1de in cmd_df (vtbl=0xf3df3f10, argc=1, argv=0xf3de32c0) at nsh_mntcmds.c:73
|#13 0x08056370 in nsh_command (vtbl=0xf3df3f10, argc=1, argv=0xf3de32c0) at nsh_command.c:1061
|#14 0x08053b16 in nsh_execute (vtbl=0xf3df3f10, argc=1, argv=0xf3de32c0, redirfile=0x0, oflags=0) at nsh_parse.c:741
|#15 0x08055998 in nsh_parse_command (vtbl=0xf3df3f10, cmdline=0xf3df4378 "df") at nsh_parse.c:2578
|#16 0x08055a7b in nsh_parse (vtbl=0xf3df3f10, cmdline=0xf3df4378 "df") at nsh_parse.c:2662
|#17 0x0805d691 in nsh_session (pstate=0xf3df3f10, login=1 '\001', argc=1, argv=0xf3de34b0) at nsh_session.c:191
|#18 0x0805b542 in nsh_consolemain (argc=1, argv=0xf3de34b0) at nsh_consolemain.c:115
|#19 0x0805346c in nsh_main (argc=1, argv=0xf3de34b0) at nsh_main.c:168
|#20 0x0805075a in nxtask_startup (entrypt=0x805340a <nsh_main>, argc=1, argv=0xf3de34b0) at sched/task_startup.c:165
|#21 0x08049713 in nxtask_start () at task/task_start.c:144
|#22 0x00000000 in ?? ()

Change-Id: Ic4c7aff0ea50388a371c525745e817a787dabcca
Signed-off-by: chao.an <anchao@xiaomi.com>

fs/unionfs/fs_unionfs.c

@@ -979,7 +979,6 @@ static ssize_t unionfs_read(FAR struct file *filep, FAR char *buffer,
   FAR struct unionfs_file_s *uf;
   FAR struct unionfs_mountpt_s *um;
   FAR const struct mountpt_operations *ops;
-  int ret = -EPERM;
 
   finfo("buflen: %lu\n", (unsigned long)buflen);
 
@@ -988,14 +987,6 @@ static ssize_t unionfs_read(FAR struct file *filep, FAR char *buffer,
   DEBUGASSERT(filep != NULL && filep->f_inode != NULL);
   ui = (FAR struct unionfs_inode_s *)filep->f_inode->i_private;
 
-  /* Get exclusive access to the file system data structures */
-
-  ret = unionfs_semtake(ui, false);
-  if (ret < 0)
-    {
-      return ret;
-    }
-
   DEBUGASSERT(ui != NULL && filep->f_priv != NULL);
   uf = (FAR struct unionfs_file_s *)filep->f_priv;
 
@@ -1008,13 +999,7 @@ static ssize_t unionfs_read(FAR struct file *filep, FAR char *buffer,
 
   /* Perform the lower level read operation */
 
-  if (ops->read != NULL)
+  return ops->read ? ops->read(&uf->uf_file, buffer, buflen) : -EPERM;
-    {
-      ret = ops->read(&uf->uf_file, buffer, buflen);
-    }
-
-  unionfs_semgive(ui);
-  return ret;
 }
 
 /****************************************************************************
@@ -1028,7 +1013,6 @@ static ssize_t unionfs_write(FAR struct file *filep, FAR const char *buffer,
   FAR struct unionfs_file_s *uf;
   FAR struct unionfs_mountpt_s *um;
   FAR const struct mountpt_operations *ops;
-  int ret = -EPERM;
 
   finfo("buflen: %lu\n", (unsigned long)buflen);
 
@@ -1037,14 +1021,6 @@ static ssize_t unionfs_write(FAR struct file *filep, FAR const char *buffer,
   DEBUGASSERT(filep != NULL && filep->f_inode != NULL);
   ui = (FAR struct unionfs_inode_s *)filep->f_inode->i_private;
 
-  /* Get exclusive access to the file system data structures */
-
-  ret = unionfs_semtake(ui, false);
-  if (ret < 0)
-    {
-      return ret;
-    }
-
   DEBUGASSERT(ui != NULL && filep->f_priv != NULL);
   uf = (FAR struct unionfs_file_s *)filep->f_priv;
 
@@ -1057,13 +1033,7 @@ static ssize_t unionfs_write(FAR struct file *filep, FAR const char *buffer,
 
   /* Perform the lower level write operation */
 
-  if (ops->write != NULL)
+  return ops->write ? ops->write(&uf->uf_file, buffer, buflen) : -EPERM;
-    {
-      ret = ops->write(&uf->uf_file, buffer, buflen);
-    }
-
-  unionfs_semgive(ui);
-  return ret;
 }
 
 /****************************************************************************
@@ -1076,7 +1046,6 @@ static off_t unionfs_seek(FAR struct file *filep, off_t offset, int whence)
   FAR struct unionfs_file_s *uf;
   FAR struct unionfs_mountpt_s *um;
   FAR const struct mountpt_operations *ops;
-  int ret;
 
   finfo("offset: %lu whence: %d\n", (unsigned long)offset, whence);
 
@@ -1085,14 +1054,6 @@ static off_t unionfs_seek(FAR struct file *filep, off_t offset, int whence)
   DEBUGASSERT(filep != NULL && filep->f_inode != NULL);
   ui = (FAR struct unionfs_inode_s *)filep->f_inode->i_private;
 
-  /* Get exclusive access to the file system data structures */
-
-  ret = unionfs_semtake(ui, false);
-  if (ret < 0)
-    {
-      return ret;
-    }
-
   DEBUGASSERT(ui != NULL && filep->f_priv != NULL);
   uf = (FAR struct unionfs_file_s *)filep->f_priv;
 
@@ -1111,6 +1072,16 @@ static off_t unionfs_seek(FAR struct file *filep, off_t offset, int whence)
     }
   else
     {
+      int ret;
+
+      /* Get exclusive access to the file system data structures */
+
+      ret = unionfs_semtake(ui, false);
+      if (ret < 0)
+        {
+          return ret;
+        }
+
       /* No... Just set the common file position value */
 
       switch (whence)
@@ -1137,9 +1108,10 @@ static off_t unionfs_seek(FAR struct file *filep, off_t offset, int whence)
             offset = (off_t)-EINVAL;
             break;
         }
+
+      unionfs_semgive(ui);
     }
 
-  unionfs_semgive(ui);
   return offset;
 }
 
@@ -1153,7 +1125,6 @@ static int unionfs_ioctl(FAR struct file *filep, int cmd, unsigned long arg)
   FAR struct unionfs_file_s *uf;
   FAR struct unionfs_mountpt_s *um;
   FAR const struct mountpt_operations *ops;
-  int ret = -ENOTTY;
 
   finfo("cmd: %d arg: %lu\n", cmd, arg);
 
@@ -1162,14 +1133,6 @@ static int unionfs_ioctl(FAR struct file *filep, int cmd, unsigned long arg)
   DEBUGASSERT(filep != NULL && filep->f_inode != NULL);
   ui = (FAR struct unionfs_inode_s *)filep->f_inode->i_private;
 
-  /* Get exclusive access to the file system data structures */
-
-  ret = unionfs_semtake(ui, false);
-  if (ret < 0)
-    {
-      return ret;
-    }
-
   DEBUGASSERT(ui != NULL && filep->f_priv != NULL);
   uf = (FAR struct unionfs_file_s *)filep->f_priv;
 
@@ -1182,13 +1145,7 @@ static int unionfs_ioctl(FAR struct file *filep, int cmd, unsigned long arg)
 
   /* Perform the lower level ioctl operation */
 
-  if (ops->ioctl != NULL)
+  return ops->ioctl ? ops->ioctl(&uf->uf_file, cmd, arg) : -ENOTTY;
-    {
-      ret = ops->ioctl(&uf->uf_file, cmd, arg);
-    }
-
-  unionfs_semgive(ui);
-  return ret;
 }
 
 /****************************************************************************
@@ -1201,7 +1158,6 @@ static int unionfs_sync(FAR struct file *filep)
   FAR struct unionfs_file_s *uf;
   FAR struct unionfs_mountpt_s *um;
   FAR const struct mountpt_operations *ops;
-  int ret = -EINVAL;
 
   finfo("filep=%p\n", filep);
 
@@ -1210,14 +1166,6 @@ static int unionfs_sync(FAR struct file *filep)
   DEBUGASSERT(filep != NULL && filep->f_inode != NULL);
   ui = (FAR struct unionfs_inode_s *)filep->f_inode->i_private;
 
-  /* Get exclusive access to the file system data structures */
-
-  ret = unionfs_semtake(ui, false);
-  if (ret < 0)
-    {
-      return ret;
-    }
-
   DEBUGASSERT(ui != NULL && filep->f_priv != NULL);
   uf = (FAR struct unionfs_file_s *)filep->f_priv;
 
@@ -1230,13 +1178,7 @@ static int unionfs_sync(FAR struct file *filep)
 
   /* Perform the lower level sync operation */
 
-  if (ops->sync != NULL)
+  return ops->sync ? ops->sync(&uf->uf_file) : -EINVAL;
-    {
-      ret = ops->sync(&uf->uf_file);
-    }
-
-  unionfs_semgive(ui);
-  return ret;
 }
 
 /****************************************************************************
@@ -1259,14 +1201,6 @@ static int unionfs_dup(FAR const struct file *oldp, FAR struct file *newp)
   DEBUGASSERT(oldp != NULL && oldp->f_inode != NULL);
   ui = (FAR struct unionfs_inode_s *)oldp->f_inode->i_private;
 
-  /* Get exclusive access to the file system data structures */
-
-  ret = unionfs_semtake(ui, false);
-  if (ret < 0)
-    {
-      return ret;
-    }
-
   DEBUGASSERT(ui != NULL && oldp->f_priv != NULL);
   oldpriv = (FAR struct unionfs_file_s *)oldp->f_priv;
 
@@ -1326,7 +1260,6 @@ static int unionfs_fstat(FAR const struct file *filep, FAR struct stat *buf)
   FAR struct unionfs_file_s *uf;
   FAR struct unionfs_mountpt_s *um;
   FAR const struct mountpt_operations *ops;
-  int ret = -EPERM;
 
   finfo("filep=%p buf=%p\n", filep, buf);
 
@@ -1335,14 +1268,6 @@ static int unionfs_fstat(FAR const struct file *filep, FAR struct stat *buf)
   DEBUGASSERT(filep != NULL && filep->f_inode != NULL);
   ui = (FAR struct unionfs_inode_s *)filep->f_inode->i_private;
 
-  /* Get exclusive access to the file system data structures */
-
-  ret = unionfs_semtake(ui, false);
-  if (ret < 0)
-    {
-      return ret;
-    }
-
   DEBUGASSERT(ui != NULL && filep->f_priv != NULL);
   uf = (FAR struct unionfs_file_s *)filep->f_priv;
 
@@ -1355,13 +1280,7 @@ static int unionfs_fstat(FAR const struct file *filep, FAR struct stat *buf)
 
   /* Perform the lower level write operation */
 
-  if (ops->fstat != NULL)
+  return ops->fstat ? ops->fstat(&uf->uf_file, buf) : -EPERM;
-    {
-      ret = ops->fstat(&uf->uf_file, buf);
-    }
-
-  unionfs_semgive(ui);
-  return ret;
 }
 
 /****************************************************************************
@@ -1378,7 +1297,6 @@ static int unionfs_truncate(FAR struct file *filep, off_t length)
   FAR struct unionfs_file_s *uf;
   FAR struct unionfs_mountpt_s *um;
   FAR const struct mountpt_operations *ops;
-  int ret = -EPERM;
 
   finfo("filep=%p length=%ld\n", filep, (long)length);
 
@@ -1387,14 +1305,6 @@ static int unionfs_truncate(FAR struct file *filep, off_t length)
   DEBUGASSERT(filep != NULL && filep->f_inode != NULL);
   ui = (FAR struct unionfs_inode_s *)filep->f_inode->i_private;
 
-  /* Get exclusive access to the file system data structures */
-
-  ret = unionfs_semtake(ui, false);
-  if (ret < 0)
-    {
-      return ret;
-    }
-
   DEBUGASSERT(ui != NULL && filep->f_priv != NULL);
   uf = (FAR struct unionfs_file_s *)filep->f_priv;
 
@@ -1407,13 +1317,7 @@ static int unionfs_truncate(FAR struct file *filep, off_t length)
 
   /* Perform the lower level write operation */
 
-  if (ops->truncate != NULL)
+  return ops->truncate ? ops->truncate(&uf->uf_file, length) : -EPERM;
-    {
-      ret = ops->truncate(&uf->uf_file, length);
-    }
-
-  unionfs_semgive(ui);
-  return ret;
 }
 
 /****************************************************************************
@@ -1940,7 +1844,7 @@ static int unionfs_rewinddir(struct inode *mountpt, struct fs_dirent_s *dir)
   FAR struct unionfs_mountpt_s *um;
   FAR const struct mountpt_operations *ops;
   FAR struct fs_unionfsdir_s *fu;
-  int ret;
+  int ret = -EINVAL;
 
   finfo("mountpt=%p dir=%p\n", mountpt, dir);
 
@@ -1949,14 +1853,6 @@ static int unionfs_rewinddir(struct inode *mountpt, struct fs_dirent_s *dir)
   DEBUGASSERT(mountpt != NULL && mountpt->i_private != NULL);
   ui = (FAR struct unionfs_inode_s *)mountpt->i_private;
 
-  /* Get exclusive access to the file system data structures */
-
-  ret = unionfs_semtake(ui, false);
-  if (ret < 0)
-    {
-      return ret;
-    }
-
   DEBUGASSERT(dir);
   fu = &dir->u.unionfs;
 
@@ -1988,13 +1884,8 @@ static int unionfs_rewinddir(struct inode *mountpt, struct fs_dirent_s *dir)
           ret = ops->rewinddir(um->um_node, fu->fu_lower[fu->fu_ndx]);
           dir->fd_position = fu->fu_lower[fu->fu_ndx]->fd_position;
         }
-      else
-        {
-          ret = -EINVAL;
-        }
     }
 
-  unionfs_semgive(ui);
   return ret;
 }
 
@@ -2085,10 +1976,14 @@ static int unionfs_unbind(FAR void *handle, FAR struct inode **blkdriver,
 
   if (ui->ui_nopen <= 0)
     {
+      unionfs_semgive(ui);
       unionfs_destroy(ui);
     }
+  else
+    {
+      unionfs_semgive(ui);
+    }
 
-  unionfs_semgive(ui);
   return OK;
 }
 
@@ -2119,14 +2014,6 @@ static int unionfs_statfs(FAR struct inode *mountpt, FAR struct statfs *buf)
 
   memset(buf, 0, sizeof(struct statfs));
 
-  /* Get exclusive access to the file system data structures */
-
-  ret = unionfs_semtake(ui, false);
-  if (ret < 0)
-    {
-      return ret;
-    }
-
   /* Get statfs info from file system 1.
    *
    * REVISIT: What would it mean if one file system did not support statfs?
@@ -2149,7 +2036,7 @@ static int unionfs_statfs(FAR struct inode *mountpt, FAR struct statfs *buf)
       ret = ops1->statfs(um1->um_node, &buf1);
       if (ret < 0)
         {
-          goto errout_with_semaphore;
+          return ret;
         }
 
       /* Get stafs info from file system 2 */
@@ -2157,29 +2044,26 @@ static int unionfs_statfs(FAR struct inode *mountpt, FAR struct statfs *buf)
       ret = ops2->statfs(um2->um_node, &buf2);
       if (ret < 0)
         {
-          goto errout_with_semaphore;
+          return ret;
         }
     }
   else if (ops1->statfs != NULL)
     {
       /* We have statfs for file system 1 only */
 
-      ret = ops1->statfs(um1->um_node, buf);
+      return ops1->statfs(um1->um_node, buf);
-      goto errout_with_semaphore;
     }
   else if (ops2->statfs != NULL)
     {
       /* We have statfs for file system 2 only */
 
-      ret = ops2->statfs(um2->um_node, buf);
+      return ops2->statfs(um2->um_node, buf);
-      goto errout_with_semaphore;
     }
   else
     {
       /* We could not get stafs info from either file system */
 
-      ret = -ENOSYS;
+      return -ENOSYS;
-      goto errout_with_semaphore;
     }
 
   /* We get here is we successfully obtained statfs info from both file
@@ -2231,11 +2115,7 @@ static int unionfs_statfs(FAR struct inode *mountpt, FAR struct statfs *buf)
   buf->f_bfree          = buf1.f_bfree  + buf2.f_bfree;
   buf->f_bavail         = buf1.f_bavail + buf2.f_bavail;
 
-  ret = OK;
+  return OK;
-
-errout_with_semaphore:
-  unionfs_semgive(ui);
-  return ret;
 }
 
 /****************************************************************************
@@ -2258,14 +2138,6 @@ static int unionfs_unlink(FAR struct inode *mountpt,
               relpath != NULL);
   ui = (FAR struct unionfs_inode_s *)mountpt->i_private;
 
-  /* Get exclusive access to the file system data structures */
-
-  ret = unionfs_semtake(ui, false);
-  if (ret < 0)
-    {
-      return ret;
-    }
-
   /* Check if some exists at this path on file system 1.  This might be
    * a file or a directory
    */
@@ -2305,7 +2177,6 @@ static int unionfs_unlink(FAR struct inode *mountpt,
         }
     }
 
-  unionfs_semgive(ui);
   return ret;
 }
 
@@ -2331,30 +2202,20 @@ static int unionfs_mkdir(FAR struct inode *mountpt, FAR const char *relpath,
               relpath != NULL);
   ui = (FAR struct unionfs_inode_s *)mountpt->i_private;
 
-  /* Get exclusive access to the file system data structures */
-
-  ret = unionfs_semtake(ui, false);
-  if (ret < 0)
-    {
-      return ret;
-    }
-
   /* Is there anything with this name on either file system? */
 
   um  = &ui->ui_fs[0];
   ret = unionfs_trystat(um->um_node, relpath, um->um_prefix, &buf);
   if (ret >= 0)
     {
-      ret = -EEXIST;
+      return -EEXIST;
-      goto errout_with_semaphore;
     }
 
   um  = &ui->ui_fs[1];
   ret = unionfs_trystat(um->um_node, relpath, um->um_prefix, &buf);
   if (ret >= 0)
     {
-      ret = -EEXIST;
+      return -EEXIST;
-      goto errout_with_semaphore;
     }
 
   /* Try to create the directory on both file systems. */
@@ -2370,20 +2231,7 @@ static int unionfs_mkdir(FAR struct inode *mountpt, FAR const char *relpath,
    * read-only and the other is write-able?
    */
 
-  if (ret1 >= 0 || ret2 >= 0)
+  return (ret1 >= 0 || ret2 >= 0) ? OK : ret1;
-    {
-      ret = OK;
-    }
-  else
-    {
-      /* Otherwise, pick one */
-
-      ret = ret1;
-    }
-
-errout_with_semaphore:
-  unionfs_semgive(ui);
-  return ret;
 }
 
 /****************************************************************************
@@ -2394,8 +2242,8 @@ static int unionfs_rmdir(FAR struct inode *mountpt, FAR const char *relpath)
 {
   FAR struct unionfs_inode_s *ui;
   FAR struct unionfs_mountpt_s *um;
+  int ret = -ENOENT;
   int tmp;
-  int ret;
 
   finfo("relpath: %s\n", relpath);
 
@@ -2405,16 +2253,6 @@ static int unionfs_rmdir(FAR struct inode *mountpt, FAR const char *relpath)
               relpath != NULL);
   ui = (FAR struct unionfs_inode_s *)mountpt->i_private;
 
-  /* Get exclusive access to the file system data structures */
-
-  ret = unionfs_semtake(ui, false);
-  if (ret < 0)
-    {
-      return ret;
-    }
-
-  ret = -ENOENT;
-
   /* We really don't know any better so we will try to remove the directory
    * from both file systems.
    */
@@ -2432,7 +2270,6 @@ static int unionfs_rmdir(FAR struct inode *mountpt, FAR const char *relpath)
       ret = unionfs_tryrmdir(um->um_node, relpath, um->um_prefix);
       if (ret < 0)
         {
-          unionfs_semgive(ui);
           return ret;
         }
     }
@@ -2456,7 +2293,6 @@ static int unionfs_rmdir(FAR struct inode *mountpt, FAR const char *relpath)
        */
     }
 
-  unionfs_semgive(ui);
   return ret;
 }
 
@@ -2470,8 +2306,8 @@ static int unionfs_rename(FAR struct inode *mountpt,
 {
   FAR struct unionfs_inode_s *ui;
   FAR struct unionfs_mountpt_s *um;
-  int tmp;
   int ret = -ENOENT;
+  int tmp;
 
   finfo("oldrelpath: %s newrelpath: %s\n", oldrelpath, newrelpath);
 
@@ -2480,14 +2316,6 @@ static int unionfs_rename(FAR struct inode *mountpt,
   DEBUGASSERT(mountpt != NULL && mountpt->i_private != NULL);
   ui = (FAR struct unionfs_inode_s *)mountpt->i_private;
 
-  /* Get exclusive access to the file system data structures */
-
-  ret = unionfs_semtake(ui, false);
-  if (ret < 0)
-    {
-      return ret;
-    }
-
   DEBUGASSERT(oldrelpath != NULL && oldrelpath != NULL);
 
   /* Is there a file with this name on file system 1 */
@@ -2510,7 +2338,6 @@ static int unionfs_rename(FAR struct inode *mountpt,
            * file of the same relative path will become visible.
            */
 
-          unionfs_semgive(ui);
           return OK;
         }
     }
@@ -2532,7 +2359,6 @@ static int unionfs_rename(FAR struct inode *mountpt,
                               um->um_prefix);
     }
 
-  unionfs_semgive(ui);
   return ret;
 }
 
@@ -2555,14 +2381,6 @@ static int unionfs_stat(FAR struct inode *mountpt, FAR const char *relpath,
               relpath != NULL);
   ui = (FAR struct unionfs_inode_s *)mountpt->i_private;
 
-  /* Get exclusive access to the file system data structures */
-
-  ret = unionfs_semtake(ui, false);
-  if (ret < 0)
-    {
-      return ret;
-    }
-
   /* stat this path on file system 1 */
 
   um  = &ui->ui_fs[0];
@@ -2573,7 +2391,6 @@ static int unionfs_stat(FAR struct inode *mountpt, FAR const char *relpath,
        * shadow the second anyway.
        */
 
-      unionfs_semgive(ui);
       return OK;
     }
 
@@ -2587,7 +2404,6 @@ static int unionfs_stat(FAR struct inode *mountpt, FAR const char *relpath,
        * shadow the second anyway.
        */
 
-      unionfs_semgive(ui);
       return OK;
     }
 
@@ -2620,7 +2436,6 @@ static int unionfs_stat(FAR struct inode *mountpt, FAR const char *relpath,
         }
     }
 
-  unionfs_semgive(ui);
   return ret;
 }
 
@@ -2818,17 +2633,6 @@ int unionfs_mount(FAR const char *fspath1, FAR const char *prefix1,
    * for now, however.
    */
 
-  /* Insert a dummy node -- we need to hold the inode semaphore
-   * to do this because we will have a momentarily bad structure.
-   * NOTE that the inode will be created with a reference count of zero.
-   */
-
-  ret = inode_semtake();
-  if (ret < 0)
-    {
-      return ret;
-    }
-
   ret = inode_reserve(mountpt, &mpinode);
   if (ret < 0)
     {
@@ -2841,7 +2645,7 @@ int unionfs_mount(FAR const char *fspath1, FAR const char *prefix1,
        */
 
       ferr("ERROR: Failed to reserve inode\n");
-      goto errout_with_semaphore;
+      return ret;
     }
 
   /* Populate the inode with driver specific information. */
@@ -2862,14 +2666,10 @@ int unionfs_mount(FAR const char *fspath1, FAR const char *prefix1,
       goto errout_with_mountpt;
     }
 
-  inode_semgive();
   return OK;
 
 errout_with_mountpt:
   inode_release(mpinode);
-
-errout_with_semaphore:
-  inode_semgive();
   return ret;
 }
 #endif /* !CONFIG_DISABLE_MOUNTPOINT && CONFIG_FS_UNIONFS */