nuttx/fs/mount/fs_umount2.c

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/****************************************************************************
* fs/mount/fs_umount2.c
*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership. The
* ASF licenses this file to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance with the
* License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
* License for the specific language governing permissions and limitations
* under the License.
*
****************************************************************************/
/****************************************************************************
* Included Files
****************************************************************************/
#include <nuttx/config.h>
#include <sys/mount.h>
#include <stdbool.h>
#include <errno.h>
#include <assert.h>
#include <nuttx/fs/fs.h>
#include "inode/inode.h"
#include "notify/notify.h"
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: nx_umount2
*
* Description:
* nx_umount2() is similar to the standard 'umount2' interface except that
* is not a cancellation point and it does not modify the errno variable.
*
* nx_umount2() is an internal NuttX interface and should not be called
* from applications.
*
* Returned Value:
* Zero is returned on success; a negated value is returned on any failure.
*
****************************************************************************/
int nx_umount2(FAR const char *target, unsigned int flags)
{
FAR struct inode *mountpt_inode;
FAR struct inode *blkdrvr_inode = NULL;
struct inode_search_s desc;
int ret;
/* Verify required pointer arguments */
if (!target)
{
ret = -EFAULT;
goto errout;
}
/* Find the mountpt */
SETUP_SEARCH(&desc, target, false);
ret = inode_find(&desc);
if (ret < 0)
{
goto errout_with_search;
}
/* Get the search results */
mountpt_inode = desc.node;
DEBUGASSERT(mountpt_inode != NULL);
/* Verify that the inode is a mountpoint */
if (!INODE_IS_MOUNTPT(mountpt_inode))
{
ret = -EINVAL;
goto errout_with_mountpt;
}
/* Unbind the block driver from the file system (destroying any fs
* private data.
*/
if (!mountpt_inode->u.i_mops->unbind)
{
/* The filesystem does not support the unbind operation ??? */
ret = -EINVAL;
goto errout_with_mountpt;
}
/* The unbind method returns the number of references to the
* filesystem (i.e., open files), zero if the unbind was
* performed, or a negated error code on a failure.
*/
/* Hold the semaphore through the unbind logic */
ret = inode_lock();
if (ret < 0)
{
goto errout_with_mountpt;
}
ret = mountpt_inode->u.i_mops->unbind(mountpt_inode->i_private,
&blkdrvr_inode, flags);
if (ret < 0)
{
/* The inode is unhappy with the blkdrvr for some reason */
goto errout_with_lock;
}
else if (ret > 0)
{
ret = -EBUSY;
goto errout_with_lock;
}
/* Successfully unbound. Convert the mountpoint inode to regular
* pseudo-file inode.
*/
mountpt_inode->i_flags &= ~FSNODEFLAG_TYPE_MASK;
mountpt_inode->i_private = NULL;
mountpt_inode->u.i_mops = NULL;
#ifndef CONFIG_DISABLE_PSEUDOFS_OPERATIONS
/* If the node has children, then do not delete it. */
if (mountpt_inode->i_child != NULL)
{
/* Just decrement the reference count (without deleting it) */
DEBUGASSERT(mountpt_inode->i_crefs > 0);
mountpt_inode->i_crefs--;
inode_unlock();
}
else
#endif
{
/* 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)
*/
ret = inode_remove(target);
inode_unlock();
/* The return value of -EBUSY is normal (in fact, it should
* not be OK)
*/
if (ret != OK && ret != -EBUSY)
{
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);
}
RELEASE_SEARCH(&desc);
#ifdef CONFIG_FS_NOTIFY
notify_unmount(target);
#endif
return OK;
/* A lot of goto's! But they make the error handling much simpler */
errout_with_lock:
inode_unlock();
errout_with_mountpt:
inode_release(mountpt_inode);
if (blkdrvr_inode)
{
inode_release(blkdrvr_inode);
}
errout_with_search:
RELEASE_SEARCH(&desc);
errout:
return ret;
}
/****************************************************************************
* Name: umount2
*
* Description:
* umount() detaches the filesystem mounted at the path specified by
* 'target.'
*
* Returned Value:
* Zero is returned on success; -1 is returned on an error and errno is
* set appropriately:
*
* EACCES A component of a path was not searchable or mounting a read-only
* filesystem was attempted without giving the MS_RDONLY flag.
* EBUSY The target could not be unmounted because it is busy.
* EFAULT The pointer argument points outside the user address space.
*
****************************************************************************/
int umount2(FAR const char *target, unsigned int flags)
{
int ret;
ret = nx_umount2(target, flags);
if (ret < 0)
{
set_errno(-ret);
ret = ERROR;
}
return ret;
}