fs/mount/fs_mount.c

/****************************************************************************
 * fs/mount/fs_mount.c
 *
 * Copyright (c) 2023 Huawei Device Co., Ltd. All rights reserved.
 * Based on NuttX originally from nuttx source (nuttx/fs/ and nuttx/drivers/)
 *
 * Licensed 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 "vfs_config.h"

#include "sys/mount.h"
#include "string.h"
#include "errno.h"
#include "assert.h"
#include "vnode.h"
#include "stdlib.h"
#ifdef LOSCFG_DRIVERS_MTD
#include "mtd_partition.h"
#endif
#ifdef LOSCFG_FS_FAT_VIRTUAL_PARTITION
#include "errcode_fat.h"
#endif
#include "los_tables.h"
#ifdef LOSCFG_DRIVERS_RANDOM
#include "hisoc/random.h"
#else
#include "stdlib.h"
#endif
#include "path_cache.h"
#include "fs/mount.h"
#include "fs/driver.h"
#include "fs/fs.h"
#ifdef LOSCFG_FS_ZPFS
#include "zpfs.h"
#endif
#ifdef LOSCFG_MNT_CONTAINER
#include "los_mnt_container_pri.h"
#endif

/* At least one filesystem must be defined, or this file will not compile.
 * It may be desire-able to make filesystems dynamically registered at
 * some time in the future, but at present, this file needs to know about
 * every configured filesystem.
 */

#ifdef CONFIG_FS_READABLE

/****************************************************************************
 * Pre-processor Definitions
 ****************************************************************************/
/* Configuration ************************************************************/
/* In the canonical case, a file system is bound to a block driver.  However,
 * some less typical cases a block driver is not required.  Examples are
 * pseudo file systems (like BINFS or PROCFS) and MTD file systems (like NXFFS).
 *
 * These file systems all require block drivers:
 */

#define BLKDRVR_NOT_MOUNTED 2

extern struct fsmap_t g_fsmap[];
LOS_HAL_TABLE_BEGIN(g_fsmap, fsmap);

extern struct fsmap_t g_fsmap_end;
LOS_HAL_TABLE_END(g_fsmap_end, fsmap);

/****************************************************************************
 * Public Data
 ****************************************************************************/

/****************************************************************************
 * Private Functions
 ****************************************************************************/

/****************************************************************************
 * Name: mount_findfs
 *
 * Description:
 *    find the specified filesystem
 *
 ****************************************************************************/

static const struct fsmap_t *mount_findfs(const char *filesystemtype)
{
  struct fsmap_t *m = NULL;

  for (m = &g_fsmap[0]; m != &g_fsmap_end; ++m)
    {
      if (m->fs_filesystemtype &&
          strcmp(filesystemtype, m->fs_filesystemtype) == 0)
        {
          return m;
        }
    }

  return (const struct fsmap_t *)NULL;
}


/****************************************************************************
 * Public Functions
 ****************************************************************************/

/****************************************************************************
 * Name: mount
 *
 * Description:
 *   mount() attaches the filesystem specified by the 'source' block device
 *   name into the root file system at the path specified by 'target.'
 *
 * Return:
 *   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 'source' is already  mounted.
 *   EFAULT One of the pointer arguments points outside the user address
 *      space.
 *   EINVAL 'source' had an invalid superblock.
 *   ENODEV 'filesystemtype' not configured
 *   ENOENT A pathname was empty or had a nonexistent component.
 *   ENOMEM Could not allocate a memory to copy filenames or data into.
 *   ENOTBLK 'source' is not a block device
 *
 ****************************************************************************/

int mount(const char *source, const char *target,
          const char *filesystemtype, unsigned long mountflags,
          const void *data)
{
  int ret;
  int errcode = 0;
  struct Mount* mnt = NULL;
  struct Vnode *device = NULL;
  struct Vnode *mountpt_vnode = NULL;
  const struct fsmap_t *fsmap = NULL;
  const struct MountOps *mops = NULL;
  LIST_HEAD *mount_list = NULL;
#ifdef LOSCFG_DRIVERS_MTD
  mtd_partition *partition = NULL;
#endif

  if (filesystemtype == NULL)
    {
      errcode = -EINVAL;
      goto errout;
    }

  /* Verify required pointer arguments */

  DEBUGASSERT(target && filesystemtype);

  /* Find the specified filesystem.  Try the block driver file systems first */

  if ((fsmap = mount_findfs(filesystemtype)) == NULL || (fsmap->is_bdfs && !source))
    {
      PRINT_ERR("Failed to find file system %s\n", filesystemtype);
      errcode = -ENODEV;
      goto errout;
    }

  mops = fsmap->fs_mops;

  if (fsmap->is_bdfs && source)
    {
      /* Make sure that a block driver argument was provided */

      DEBUGASSERT(source);

      /* Find the block driver */

      ret = find_blockdriver(source, mountflags, &device);
      if (ret < 0)
        {
          PRINT_ERR("Failed to find block driver %s\n", source);
          errcode = ret;
          goto errout;
        }
    }

  VnodeHold();
  ret = VnodeLookup(target, &mountpt_vnode, 0);

  /* The mount point must be an existed vnode. */

  if (ret != OK)
    {
      PRINT_ERR("Failed to find valid mountpoint %s\n", target);
      errcode = -EINVAL;
      goto errout_with_lock;
    }
  if (mountpt_vnode->flag & VNODE_FLAG_MOUNT_NEW)
    {
#ifdef LOSCFG_MNT_CONTAINER
      struct Mount *tMnt = NULL;
      LOS_DL_LIST_FOR_EACH_ENTRY(tMnt, GetMountList(), struct Mount, mountList)
        {
          if (tMnt->vnodeCovered == mountpt_vnode)
            {
              PRINT_ERR("can't mount to %s, already mounted.\n", target);
              errcode = -EINVAL;
              goto errout_with_lock;
            }
        }
#else
      PRINT_ERR("can't mount to %s, already mounted.\n", target);
      errcode = -EINVAL;
      goto errout_with_lock;
#endif
    }

#ifdef LOSCFG_MNT_CONTAINER
    struct Mount *cacheMnt = NULL;
    if (source != NULL)
      {
        LOS_DL_LIST_FOR_EACH_ENTRY(cacheMnt, GetMountCache(), struct Mount, mountList)
          {
            if (strcmp(cacheMnt->devName, source) == 0)
              {
                struct Mount *newMnt = (struct Mount *)zalloc(sizeof(struct Mount));
                if (newMnt == NULL)
                  {
                    PRINT_ERR("New mount alloc failed no memory!\n");
                    errcode = -EINVAL;
                    goto errout;
                  }
                *newMnt = *cacheMnt;
                LOS_ListTailInsert(GetMountList(), &(newMnt->mountList));
                cacheMnt->vnodeCovered->mntCount++;
                VnodeDrop();
                return OK;
              }
          }
      }
#endif
  /* Bind the block driver to an instance of the file system.  The file
   * system returns a reference to some opaque, fs-dependent structure
   * that encapsulates this binding.
   */

  if (mops->Mount == NULL)
    {
      /* The filesystem does not support the bind operation ??? */

      PRINTK("ERROR: Filesystem does not support bind\n");
      errcode = -ENOSYS;
      goto errout_with_lock;
    }

  /* Increment reference count for the reference we pass to the file system */
#ifdef LOSCFG_DRIVERS_MTD
  if (fsmap->is_mtd_support && (device != NULL))
    {
      partition = (mtd_partition *)((struct drv_data *)device->data)->priv;
      partition->mountpoint_name = (char *)zalloc(strlen(target) + 1);
      if (partition->mountpoint_name == NULL)
        {
          errcode = -ENOMEM;
          goto errout_with_lock;
        }
      (void)strncpy_s(partition->mountpoint_name, strlen(target) + 1, target, strlen(target));
      partition->mountpoint_name[strlen(target)] = '\0';
    }
#endif

  mnt = MountAlloc(mountpt_vnode, (struct MountOps*)mops);

#ifdef LOSCFG_FS_ZPFS
  if (strcmp(filesystemtype, ZPFS_NAME) == 0)
    {
      ret = ZpfsPrepare(source, target, mnt);
      if (ret < 0)
        {
          errcode = ret;
          goto errout_with_mountpt;
        }
    }
#endif

  mnt->mountFlags = mountflags;

  mountpt_vnode->useCount++;
  ret = mops->Mount(mnt, device, data);
  mountpt_vnode->useCount--;
  if (ret != 0)
    {
      /* The vnode is unhappy with the blkdrvr for some reason.  Back out
       * the count for the reference we failed to pass and exit with an
       * error.
       */

      PRINT_ERR("Bind method failed: %d\n", ret);
      errcode = ret;
#ifdef LOSCFG_DRIVERS_MTD
      if (fsmap->is_mtd_support && (device != NULL) && (partition != NULL))
        {
          free(partition->mountpoint_name);
          partition->mountpoint_name = NULL;
        }
#endif
      goto errout_with_mountpt;
    }
  mnt->vnodeBeCovered->flag |= VNODE_FLAG_MOUNT_ORIGIN;
  mnt->vnodeCovered->flag |= VNODE_FLAG_MOUNT_NEW;
  mnt->vnodeCovered->filePath = strdup(mountpt_vnode->filePath);
  mnt->vnodeDev = device;
  mnt->ops = mops;
  if (target && (strlen(target) != 0))
    {
      ret = strcpy_s(mnt->pathName, PATH_MAX, target);
      if (ret != EOK)
        {
          PRINT_ERR("Failed to copy mount point pathname, errno %d\n", ret);
        }
    }

  if (source && (strlen(source) != 0))
    {
      ret = strcpy_s(mnt->devName, PATH_MAX, source);
      if (ret != EOK)
        {
          PRINT_ERR("Failed to copy dev name, errno %d\n", ret);
        }
    }

  //* We have it, now populate it with driver specific information. */

  mount_list = GetMountList();
  LOS_ListAdd(mount_list, &mnt->mountList);

#ifdef LOSCFG_MNT_CONTAINER
  if (source != NULL)
    {
      struct Mount *newMnt = (struct Mount *)zalloc(sizeof(struct Mount));
      if (newMnt == NULL)
        {
          PRINT_ERR("New mount alloc failed no memory!\n");
          errcode = -EINVAL;
          goto errout;
        }
      *newMnt = *mnt;
      LOS_ListTailInsert(GetMountCache(), &(newMnt->mountList));
    }
#endif

  if (!strcmp("/", target))
    {
      ChangeRoot(mnt->vnodeCovered);
    }

  VnodeDrop();

  /* We can release our reference to the blkdrver_vnode, if the filesystem
   * wants to retain the blockdriver vnode (which it should), then it must
   * have called vnode_addref().  There is one reference on mountpt_vnode
   * that will persist until umount() is called.
   */

  return OK;

  /* A lot of goto's!  But they make the error handling much simpler */

errout_with_mountpt:
  if (mnt)
    {
      free(mnt);
    }
errout_with_lock:
  VnodeDrop();
errout:
  set_errno(-errcode);
  return VFS_ERROR;
}
#endif /* CONFIG_FS_READABLE */