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, 23 insertions, 132 deletions

diff --git a/cpukit/libcsupport/src/unmount.c b/cpukit/libcsupport/src/unmount.c
index a2c67f7098..5f65e588d0 100644
--- a/cpukit/libcsupport/src/unmount.c
+++ b/cpukit/libcsupport/src/unmount.c
@@ -17,146 +17,37 @@
  */
 
 #if HAVE_CONFIG_H
-#include "config.h"
+  #include "config.h"
 #endif
 
-#include <sys/types.h>
-#include <sys/stat.h>
-#include <fcntl.h>
-#include <unistd.h>
 #include <errno.h>
-#include <stdlib.h>
-#include <string.h>
 
 #include <rtems/libio_.h>
-#include <rtems/seterr.h>
-#include <rtems/chain.h>
 
-static bool is_fs_below_mount_point(
-  const rtems_filesystem_mount_table_entry_t *mt_entry,
-  void *arg
-)
+int unmount( const char *path )
 {
-  return arg == mt_entry->mt_point_node.mt_entry;
-}
-
-/*
- *  unmount
- *
- *  This routine will attempt to unmount the file system that has been
- *  is mounted a path.  If the operation is successful, 0 will
- *  be returned to the calling routine.  Otherwise, 1 will be returned.
- */
-
-int unmount(
-  const char *path
-)
-{
-  rtems_filesystem_location_info_t      loc;
-  rtems_filesystem_location_info_t     *fs_root_loc;
-  rtems_filesystem_location_info_t     *fs_mount_loc;
-  rtems_filesystem_mount_table_entry_t *mt_entry;
-
-  /*
-   *  Get
-   *    The root node of the mounted filesytem.
-   *    The node for the directory that the fileystem is mounted on.
-   *    The mount entry that is being refered to.
-   */
-
-  if ( rtems_filesystem_evaluate_path( path, strlen( path ), 0x0, &loc, true ) )
-    return -1;
-
-  mt_entry     = loc.mt_entry;
-  fs_mount_loc = &mt_entry->mt_point_node;
-  fs_root_loc  = &mt_entry->mt_fs_root;
-
-  /*
-   * Verify this is the root node for the file system to be unmounted.
-   */
-
-  if ( fs_root_loc->node_access != loc.node_access ){
-    rtems_filesystem_freenode( &loc );
-    rtems_set_errno_and_return_minus_one( EACCES );
-  }
-
-  /*
-   * Free the loc node and just use the nodes from the mt_entry .
-   */
-
-  rtems_filesystem_freenode( &loc );
-
-  /*
-   *  Verify the current node is not in this filesystem.
-   *  XXX - Joel I have a question here wasn't code added
-   *        that made the current node thread based instead
-   *        of system based?  I thought it was but it doesn't
-   *        look like it in this version.
-   */
-
-  if ( rtems_filesystem_current.mt_entry == mt_entry )
-    rtems_set_errno_and_return_minus_one( EBUSY );
-
-  /*
-   *  Verify there are no file systems below the path specified
-   */
-
-  if ( rtems_filesystem_mount_iterate( is_fs_below_mount_point,
-                                       fs_root_loc->mt_entry ) )
-    rtems_set_errno_and_return_minus_one( EBUSY );
-
-  /*
-   *  Run the file descriptor table to determine if there are any file
-   *  descriptors that are currently active and reference nodes in the
-   *  file system that we are trying to unmount
-   */
-
-  if ( rtems_libio_is_open_files_in_fs( mt_entry ) == 1 )
-    rtems_set_errno_and_return_minus_one( EBUSY );
-
-  /*
-   * Allow the file system being unmounted on to do its cleanup.
-   * If it fails it will set the errno to the approprate value
-   * and the fileystem will not be modified.
-   */
-
-  if (( fs_mount_loc->ops->unmount_h )( mt_entry ) != 0 )
-    return -1;
-
-  /*
-   *  Allow the mounted filesystem to unmark the use of the root node.
-   *
-   *  Run the unmount function for the subordinate file system.
-   *
-   *  If we fail to unmount the filesystem remount it on the base filesystems
-   *  directory node.
-   *
-   *  NOTE:  Fatal error is called in a case which should never happen
-   *         This was response was questionable but the best we could
-   *         come up with.
-   */
-
-  if ((fs_root_loc->ops->fsunmount_me_h )( mt_entry ) != 0){
-    if (( fs_mount_loc->ops->mount_h )( mt_entry ) != 0 )
-      rtems_fatal_error_occurred( 0 );
-    return -1;
+  int rv = 0;
+  rtems_filesystem_eval_path_context_t ctx;
+  int eval_flags = RTEMS_LIBIO_FOLLOW_LINK;
+  const rtems_filesystem_location_info_t *currentloc =
+    rtems_filesystem_eval_path_start( &ctx, path, eval_flags );
+  rtems_filesystem_mount_table_entry_t *mt_entry = currentloc->mt_entry;
+
+  if ( rtems_filesystem_location_is_root( currentloc ) ) {
+    rv = (*mt_entry->mt_point_node->location.ops->unmount_h)( mt_entry );
+    if ( rv == 0 ) {
+      rtems_filesystem_mt_entry_declare_lock_context( lock_context );
+
+      rtems_filesystem_mt_entry_lock( lock_context );
+      mt_entry->mounted = false;
+      rtems_filesystem_mt_entry_unlock( lock_context );
+    }
+  } else {
+    errno = EACCES;
+    rv = -1;
   }
 
-  /*
-   *  Extract the mount table entry from the chain
-   */
-
-  rtems_libio_lock();
-  rtems_chain_extract( &mt_entry->Node );
-  rtems_libio_unlock();
-
-  /*
-   *  Free the memory node that was allocated in mount
-   *  Free the memory associated with the extracted mount table entry.
-   */
-
-  rtems_filesystem_freenode( fs_mount_loc );
-  free( mt_entry );
+  rtems_filesystem_eval_path_cleanup( &ctx );
 
-  return 0;
+  return rv;
 }