Filesystem: Reference counting for locations

 o A new data structure rtems_filesystem_global_location_t was
   introduced to be used for
    o the mount point location in the mount table entry,
    o the file system root location in the mount table entry,
    o the root directory location in the user environment, and
    o the current directory location in the user environment.
   During the path evaluation global start locations are obtained to
   ensure that the current file system instance will be not unmounted in
   the meantime.
 o The user environment uses now reference counting and is protected
   from concurrent access.
 o The path evaluation process was completely rewritten and simplified.
   The IMFS, RFS, NFS, and DOSFS use now a generic path evaluation
   method.  Recursive calls in the path evaluation have been replaced
   with iteration to avoid stack overflows.  Only the evaluation of
   symbolic links is recursive.  No dynamic memory allocations and
   intermediate buffers are used in the high level path evaluation.  No
   global locks are held during the file system instance specific path
   evaluation process.
 o Recursive symbolic link evaluation is now limited by
   RTEMS_FILESYSTEM_SYMLOOP_MAX.  Applications can retrieve this value
   via sysconf().
 o The device file system (devFS) uses now no global variables and
   allocation from the workspace.  Node names are allocated from the
   heap.
 o The upper layer lseek() performs now some parameter checks.
 o The upper layer ftruncate() performs now some parameter checks.
 o unmask() is now restricted to the RWX flags and protected from
   concurrent access.
 o The fchmod_h and rmnod_h file system node handlers are now a file
   system operation.
 o The unlink_h operation has been removed.  All nodes are now destroyed
   with the rmnod_h operation.
 o New lock_h, unlock_h, clonenod_h, and are_nodes_equal_h file system
   operations.
 o The path evaluation and file system operations are now protected by
   per file system instance lock and unlock operations.
 o Fix and test file descriptor duplicate in fcntl().
 o New test fstests/fsnofs01.

1 files changed, 21 insertions, 42 deletions

diff --git a/cpukit/libfs/src/imfs/imfs_unmount.c b/cpukit/libfs/src/imfs/imfs_unmount.c
index ee1482bfa5..47acec9320 100644
--- a/cpukit/libfs/src/imfs/imfs_unmount.c
+++ b/cpukit/libfs/src/imfs/imfs_unmount.c
@@ -1,17 +1,12 @@
 /*
  *  IMFS_unmount
  *
- *  This routine will look at a mount table entry that we are going to
- *  add to the mount table. If the mount point
- *  rtems_filesystem_location_info_t struct refers to a node that is a
- *  directory that has a file system mounted on it, the node will be
- *  marked as a mount point by * setting its directory.mt_fs pointer
- *  to NULL. This indicates that a directory is no longer mounted on
- *  this node.
- *
  *  COPYRIGHT (c) 1989-1999.
  *  On-Line Applications Research Corporation (OAR).
  *
+ *  Modifications to support reference counting in the file system are
+ *  Copyright (c) 2012 embedded brains GmbH.
+ *
  *  The license and distribution terms for this file may be
  *  found in the file LICENSE in this distribution or at
  *  http://www.rtems.com/license/LICENSE.
@@ -20,43 +15,27 @@
  */
 
 #if HAVE_CONFIG_H
-#include "config.h"
+  #include "config.h"
 #endif
 
-#include <errno.h>
-
 #include "imfs.h"
-#include <rtems/libio_.h>
-#include <rtems/seterr.h>
 
-int IMFS_unmount(
-  rtems_filesystem_mount_table_entry_t *mt_entry
-)
+int IMFS_unmount( rtems_filesystem_mount_table_entry_t *mt_entry )
 {
-  IMFS_jnode_t  *node;
-
-  node = mt_entry->mt_point_node.node_access;
-
-  /*
-   * Is the node that we are mounting onto a directory node ?
-   */
-
-  if ( node->type != IMFS_DIRECTORY )
-    rtems_set_errno_and_return_minus_one( ENOTDIR );
-
-  /*
-   * Did the node indicate that there was a directory mounted here?
-   */
-
-  if ( node->info.directory.mt_fs == NULL )
-    rtems_set_errno_and_return_minus_one( EINVAL );  /* XXX */
-
-  /*
-   * Set the mt_fs pointer to indicate that there is no longer
-   * a file system mounted to this point.
-   */
-
-  node->info.directory.mt_fs = NULL;
-
-  return 0;
+  int rv = 0;
+  IMFS_jnode_t *node = mt_entry->mt_point_node->location.node_access;
+
+  if ( node->type == IMFS_DIRECTORY ) {
+    if ( node->info.directory.mt_fs == mt_entry ) {
+      node->info.directory.mt_fs = NULL;
+    } else {
+      errno = EINVAL;
+      rv = -1;
+    }
+  } else {
+    errno = ENOTDIR;
+    rv = -1;
+  }
+
+  return rv;
 }