Fix reference count problem

git-svn-id: svn://svn.code.sf.net/p/nuttx/code/trunk@258 42af7a65-404d-4744-a932-0658087f49c3

ChangeLog

@@ -152,5 +152,6 @@
 
 	* Added stat() to fs layer
 	* Added stat() supported to FAT
+	* Fixed reference counting errors associated with mounted filesystems
 	* Started m68322
 

Documentation/NuttX.html

@@ -586,6 +586,7 @@ Other memory:
 
 	* Added stat() to fs layer
 	* Added stat() supported to FAT
+	* Fixed reference counting errors associated with mounted filesystems
 	* Started m68322
 </pre></ul>
 

examples/mount/mount_main.c

@@ -53,6 +53,9 @@
  * Definitions
  ****************************************************************************/
 
+#define TEST_USE_STAT         1
+#define TEST_SHOW_DIRECTORIES 1
+
 /****************************************************************************
  * Private Types
  ****************************************************************************/
@@ -83,6 +86,7 @@ static char       g_namebuffer[256];
  * Private Functions
  ****************************************************************************/
 
+#ifdef TEST_USE_STAT
 static void show_stat(const char *path, struct stat *ps)
 {
   printf("%s stat:\n", path);
@@ -111,15 +115,17 @@ static void show_stat(const char *path, struct stat *ps)
   printf("\tsize        : %d (bytes)\n",  ps->st_size);
   printf("\tblock size  : %d (bytes)\n",  ps->st_blksize);
   printf("\tsize        : %d (blocks)\n", ps->st_blocks);
-  printf("\taccess time : %d (blocks)\n", ps->st_atime);
-  printf("\tmodify time : %d (blocks)\n", ps->st_mtime);
-  printf("\tchange time : %d (blocks)\n", ps->st_ctime);
+  printf("\taccess time : %d\n", ps->st_atime);
+  printf("\tmodify time : %d\n", ps->st_mtime);
+  printf("\tchange time : %d\n", ps->st_ctime);
 }
+#endif
 
 /****************************************************************************
  * Name: show_directories
  ****************************************************************************/
 
+#ifdef TEST_SHOW_DIRECTORIES
 static void show_directories(const char *path, int indent)
 {
   DIR *dirp;
@@ -157,6 +163,9 @@ static void show_directories(const char *path, int indent)
 
   closedir(dirp);
 }
+#else
+# define show_directories(p,i)
+#endif
 
 /****************************************************************************
  * Name: fail_read_open
@@ -446,6 +455,7 @@ static void succeed_rename(const char *oldpath, const char *newpath)
  * Name: fail_stat
  ****************************************************************************/
 
+#ifdef TEST_USE_STAT
 static void fail_stat(const char *path, int expectederror)
 {
   struct stat buf;
@@ -469,11 +479,15 @@ static void fail_stat(const char *path, int expectederror)
       g_nerrors++;
     }
 }
+#else
+# define fail_stat(p,e);
+#endif
 
 /****************************************************************************
  * Name: succeed_stat
  ****************************************************************************/
 
+#ifdef TEST_USE_STAT
 static void succeed_stat(const char *path)
 {
   struct stat buf;
@@ -494,6 +508,9 @@ static void succeed_stat(const char *path)
       show_stat(path, &buf);
     }
 }
+#else
+#define succeed_stat(p)
+#endif
 
 /****************************************************************************
  * Public Functions

fs/fs_fat32.c

@@ -91,7 +91,7 @@ static int     fat_rewinddir(struct inode *mountpt, struct internal_dir_s *dir);
 
 static int     fat_bind(FAR struct inode *blkdriver, const void *data,
                         void **handle);
-static int     fat_unbind(void *handle);
+static int     fat_unbind(void *handle, FAR struct inode **blkdriver);
 static int     fat_unlink(struct inode *mountpt, const char *relpath);
 static int     fat_mkdir(struct inode *mountpt, const char *relpath,
                          mode_t mode);
@@ -1517,7 +1517,7 @@ static int fat_bind(FAR struct inode *blkdriver, const void *data,
  *
  ****************************************************************************/
 
-static int fat_unbind(void *handle)
+static int fat_unbind(void *handle, FAR struct inode **blkdriver)
 {
   struct fat_mountpt_s *fs = (struct fat_mountpt_s*)handle;
   int ret;
@@ -1551,9 +1551,16 @@ static int fat_unbind(void *handle)
                   (void)inode->u.i_bops->close(inode);
                 }
 
-              /* Release our reference to the block driver */
+              /* We hold a reference to the block driver but should
+               * not but mucking with inodes in this context.  So, we will just return
+               * our contained reference to the block driver inode and let the umount
+               * logic dispose of it.
+               */
 
-              inode_release(inode);
+              if (blkdriver)
+                {
+                  *blkdriver = inode;
+                }
             }
         }
 

fs/fs_inoderemove.c

@@ -136,6 +136,7 @@ STATUS inode_remove(const char *path)
             */
 
            node->i_flags |= FSNODEFLAG_DELETED;
+           return -EBUSY;
          }
        else
          {
@@ -149,5 +150,5 @@ STATUS inode_remove(const char *path)
 
   /* The node does not exist or it has references */
 
-  return ERROR;
+  return -ENOENT;
 }

fs/fs_umount.c

@@ -92,7 +92,8 @@
 int umount(const char *target)
 {
   FAR struct inode *mountpt_inode;
-  int errcode;
+  FAR struct inode *blkdrvr_inode = NULL;
+  int errcode = OK;
   int status;
 
   /* Verify required pointer arguments */
@@ -138,7 +139,7 @@ int umount(const char *target)
    */
 
   inode_semtake(); /* Hold the semaphore through the unbind logic */
-  status = mountpt_inode->u.i_mops->unbind( mountpt_inode->i_private );
+  status = mountpt_inode->u.i_mops->unbind( mountpt_inode->i_private, &blkdrvr_inode);
   if (status < 0)
     {
       /* The inode is unhappy with the blkdrvr for some reason */
@@ -156,15 +157,39 @@ int umount(const char *target)
 
   mountpt_inode->i_private = NULL;
 
-  /* Remove the inode */
+  /* Successfully unbound, remove the mountpoint inode from
+   * the inode tree.  The inode will not be deleted yet because
+   * there is still at least reference on it (from the mount)
+   */
 
-  inode_semgive(); /* Need to release for inode_release */
-  inode_release(mountpt_inode);
-
-  inode_semtake(); /* Need to hold for inode_remove */
   status = inode_remove(target);
   inode_semgive();
-  return status;
+
+  /* The return value of -EBUSY is normal (in fact, it should
+   * not be OK)
+   */
+
+  if (status != OK && status != -EBUSY)
+    {
+      errcode = -status;
+      goto errout_with_mountpt;
+    }
+
+  /* Release the mountpoint inode and any block driver inode
+   * returned by the file system unbind above.  This should cause
+   * the inode to be deleted (unless there are other references)
+   */
+
+  inode_release(mountpt_inode);
+
+  /* Did the unbind method return a contained block driver */
+
+  if (blkdrvr_inode)
+    {
+      inode_release(blkdrvr_inode);
+    }
+
+  return OK;
 
   /* A lot of goto's!  But they make the error handling much simpler */
 
@@ -172,6 +197,10 @@ int umount(const char *target)
   inode_semgive();
  errout_with_mountpt:
   inode_release(mountpt_inode);
+  if (blkdrvr_inode)
+    {
+      inode_release(blkdrvr_inode);
+    }
  errout:
   *get_errno_ptr() = errcode;
   return ERROR;

include/nuttx/fs.h

@@ -157,7 +157,7 @@ struct mountpt_operations
   /* General volume-related mountpoint operations: */
 
   int     (*bind)(FAR struct inode *blkdriver, const void *data, void **handle);
-  int     (*unbind)(void *handle);
+  int     (*unbind)(void *handle, FAR struct inode **blkdriver);
 
   int     (*unlink)(struct inode *mountpt, const char *relpath);
   int     (*mkdir)(struct inode *mountpt, const char *relpath, mode_t mode);