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/*-
* Copyright 2021 Toomas Soome <tsoome@me.com>
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include <stand.h>
#include <sys/queue.h>
/*
* While setting "currdev" environment variable, alse "mount" the
* new root file system. This is done to hold disk device open
* in between file accesses, and thus preserve block cache for
* this device. Additionally, this allows us to optimize filesystem
* access by sharing filesystem metadata (like superblock).
*/
typedef STAILQ_HEAD(mnt_info_list, mnt_info) mnt_info_list_t;
typedef struct mnt_info {
STAILQ_ENTRY(mnt_info) mnt_link; /* link in mount list */
const struct fs_ops *mnt_fs;
char *mnt_dev;
char *mnt_path;
unsigned mnt_refcount;
void *mnt_data; /* Private state */
} mnt_info_t;
/* list of mounted filesystems. */
static mnt_info_list_t mnt_list = STAILQ_HEAD_INITIALIZER(mnt_list);
static void
free_mnt(mnt_info_t *mnt)
{
free(mnt->mnt_dev);
free(mnt->mnt_path);
free(mnt);
}
static int
add_mnt_info(struct fs_ops *fs, const char *dev, const char *path, void *data)
{
mnt_info_t *mnt;
mnt = malloc(sizeof(*mnt));
if (mnt == NULL)
return (ENOMEM);
mnt->mnt_fs = fs;
mnt->mnt_dev = strdup(dev);
mnt->mnt_path = strdup(path);
mnt->mnt_data = data;
mnt->mnt_refcount = 1;
if (mnt->mnt_dev == NULL || mnt->mnt_path == NULL) {
free_mnt(mnt);
return (ENOMEM);
}
STAILQ_INSERT_TAIL(&mnt_list, mnt, mnt_link);
return (0);
}
static void
delete_mnt_info(mnt_info_t *mnt)
{
STAILQ_REMOVE(&mnt_list, mnt, mnt_info, mnt_link);
free_mnt(mnt);
}
int
mount(const char *dev, const char *path, int flags __unused, void *data)
{
mnt_info_t *mnt;
int rc = -1;
/* Is it already mounted? */
STAILQ_FOREACH(mnt, &mnt_list, mnt_link) {
if (strcmp(dev, mnt->mnt_dev) == 0 &&
strcmp(path, mnt->mnt_path) == 0) {
mnt->mnt_refcount++;
return (0);
}
}
for (int i = 0; file_system[i] != NULL; i++) {
struct fs_ops *fs;
fs = file_system[i];
if (fs->fo_mount == NULL)
continue;
if (fs->fo_mount(dev, path, &data) != 0)
continue;
rc = add_mnt_info(fs, dev, path, data);
if (rc != 0 && mnt->mnt_fs->fo_unmount != NULL) {
printf("failed to mount %s: %s\n", dev,
strerror(rc));
(void)mnt->mnt_fs->fo_unmount(dev, data);
}
break;
}
/*
* if rc is -1, it means we have no file system with fo_mount()
* callback, or all fo_mount() calls failed. As long as we
* have missing fo_mount() callbacks, we allow mount() to return 0.
*/
if (rc == -1)
rc = 0;
return (rc);
}
int
unmount(const char *dev, int flags __unused)
{
mnt_info_t *mnt;
int rv;
rv = 0;
STAILQ_FOREACH(mnt, &mnt_list, mnt_link) {
if (strcmp(dev, mnt->mnt_dev) == 0) {
if (mnt->mnt_refcount > 1) {
mnt->mnt_refcount--;
break;
}
if (mnt->mnt_fs->fo_unmount != NULL)
rv = mnt->mnt_fs->fo_unmount(dev,
mnt->mnt_data);
delete_mnt_info(mnt);
break;
}
}
if (rv != 0)
printf("failed to unmount %s: %d\n", dev, rv);
return (0);
}