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fd/dirent, fs/driver/, and fs/vfs: Make MTD device accessible via a character driver proxy like block devices
This commit is contained in:
Xiang Xiao
Gregory Nutt
@@ -0,0 +1,221 @@
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/****************************************************************************
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* fs/driver/fs_mtdproxy.c
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*
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* Copyright (C) 2018 Pinecone Inc. All rights reserved.
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* Author: Xiang Xiao <xiaoxiang@pinecone.net>
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in
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* the documentation and/or other materials provided with the
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* distribution.
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* 3. Neither the name NuttX nor the names of its contributors may be
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* used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
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* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
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* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
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* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
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* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*
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****************************************************************************/
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/****************************************************************************
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* Included Files
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****************************************************************************/
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#include <nuttx/config.h>
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <stdio.h>
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#include <semaphore.h>
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#include <string.h>
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#include <errno.h>
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#include <assert.h>
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#include <debug.h>
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#include <nuttx/kmalloc.h>
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#include <nuttx/mtd/mtd.h>
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#include "driver/driver.h"
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/****************************************************************************
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* Private Data
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****************************************************************************/
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static uint32_t g_devno;
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static sem_t g_devno_sem = SEM_INITIALIZER(1);
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/****************************************************************************
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* Private Functions
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****************************************************************************/
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/****************************************************************************
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* Name: unique_blkdev
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*
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* Description:
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* Create a unique temporary device name in the /dev/ directory of the
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* pseudo-file system. We cannot use mktemp for this because it will
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* attempt to open() the file.
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*
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* Input Parameters:
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* None
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*
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* Returned Value:
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* The allocated path to the device. This must be released by the caller
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* to prevent memory links. NULL will be returned only the case where
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* we fail to allocate memory.
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*
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****************************************************************************/
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static FAR char *unique_blkdev(void)
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{
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struct stat statbuf;
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char devbuf[16];
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uint32_t devno;
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int ret;
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/* Loop until we get a unique device name */
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for (; ; )
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{
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/* Get the semaphore protecting the path number */
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do
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{
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ret = nxsem_wait(&g_devno_sem);
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/* The only case that an error should occur here is if the wait
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* was awakened by a signal.
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*/
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DEBUGASSERT(ret == OK || ret == -EINTR);
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}
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while (ret == -EINTR);
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/* Get the next device number and release the semaphore */
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devno = ++g_devno;
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nxsem_post(&g_devno_sem);
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/* Construct the full device number */
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devno &= 0xffffff;
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snprintf(devbuf, 16, "/dev/tmpb%06lx", (unsigned long)devno);
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/* Make sure that file name is not in use */
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ret = stat(devbuf, &statbuf);
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if (ret < 0)
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{
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DEBUGASSERT(errno == ENOENT);
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return strdup(devbuf);
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}
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/* It is in use, try again */
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}
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}
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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/****************************************************************************
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* Name: mtd_proxy
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*
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* Description:
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* Create a temporary block driver using drivers/mtd/ftl to mediate block
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* oriented accessed to the mtd driver.
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*
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* Input Parameters:
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* mtddev - The path to the mtd driver
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* mountflags - if MS_RDONLY is not set, then driver must support write
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* operations (see include/sys/mount.h)
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* ppinode - address of the location to return the inode reference
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*
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* Returned Value:
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* If zero, non-zero inode pointer is returned on success. This
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* is the inode pointer of the nameless block driver that mediates
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* accesses to the mtd driver.
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*
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* Errors that may be returned:
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*
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* ENOMEM - Failed to create a temporay path name.
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*
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* Plus:
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*
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* - Errors reported from ftl_initialize()
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* - Errors reported from open() or unlink()
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*
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****************************************************************************/
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int mtd_proxy(FAR const char *mtddev, int mountflags,
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FAR struct inode **ppinode)
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{
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FAR struct inode *mtd;
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FAR char *blkdev;
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int ret;
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/* Create a unique temporary file name for the block device */
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blkdev = unique_blkdev();
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if (blkdev == NULL)
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{
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ferr("ERROR: Failed to create temporary device name\n");
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return -ENOMEM;
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}
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/* Wrap the mtd driver with an instance of the ftl driver */
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ret = find_mtddriver(mtddev, &mtd);
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if (ret < 0)
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{
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ferr("ERROR: Failed to find %s mtd driver\n", mtddev);
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goto out_with_blkdev;
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}
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ret = ftl_initialize_by_path(blkdev, mtd->u.i_mtd);
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inode_release(mtd);
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if (ret < 0)
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{
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ferr("ERROR: ftl_initialize_by_path(%s, %s) failed: %d\n",
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mtddev, blkdev, ret);
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goto out_with_blkdev;
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}
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/* Open the newly created block driver */
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ret = open_blockdriver(blkdev, mountflags, ppinode);
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if (ret < 0)
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{
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ferr("ERROR: Failed to open %s: %d\n", blkdev, ret);
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goto out_with_fltdev;
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}
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/* Unlink and free the block device name. The driver instance will persist,
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* provided that CONFIG_DISABLE_PSEUDOFS_OPERATIONS=y (otherwise, we have
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* a problem here!)
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*/
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out_with_fltdev:
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unlink(blkdev);
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out_with_blkdev:
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kmm_free(blkdev);
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return ret;
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}
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