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utils.c
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/*
* Copyright (C) 2007 Oracle. All rights reserved.
* Copyright (C) 2008 Morey Roof. All rights reserved.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public
* License v2 as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public
* License along with this program; if not, write to the
* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
* Boston, MA 021110-1307, USA.
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/ioctl.h>
#include <sys/mount.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/sysinfo.h>
#include <uuid/uuid.h>
#include <fcntl.h>
#include <unistd.h>
#include <mntent.h>
#include <ctype.h>
#include <limits.h>
#include <blkid/blkid.h>
#include <sys/vfs.h>
#include <sys/statfs.h>
#include <linux/magic.h>
#include <getopt.h>
#include <btrfsutil.h>
#include "kerncompat.h"
#include "kernel-lib/radix-tree.h"
#include "kernel-shared/ctree.h"
#include "kernel-shared/disk-io.h"
#include "kernel-shared/transaction.h"
#include "crypto/crc32c.h"
#include "common/utils.h"
#include "common/path-utils.h"
#include "common/device-scan.h"
#include "kernel-shared/volumes.h"
#include "ioctl.h"
#include "cmds/commands.h"
#include "common/open-utils.h"
#include "mkfs/common.h"
static int rand_seed_initialized = 0;
static unsigned short rand_seed[3];
struct btrfs_config bconf;
struct pending_dir {
struct list_head list;
char name[PATH_MAX];
};
/*
* Checks to make sure that the label matches our requirements.
* Returns:
0 if everything is safe and usable
-1 if the label is too long
*/
static int check_label(const char *input)
{
int len = strlen(input);
if (len > BTRFS_LABEL_SIZE - 1) {
error("label %s is too long (max %d)", input,
BTRFS_LABEL_SIZE - 1);
return -1;
}
return 0;
}
static int set_label_unmounted(const char *dev, const char *label)
{
struct btrfs_trans_handle *trans;
struct btrfs_root *root;
int ret;
ret = check_mounted(dev);
if (ret < 0) {
error("checking mount status of %s failed: %d", dev, ret);
return -1;
}
if (ret > 0) {
error("device %s is mounted, use mount point", dev);
return -1;
}
/* Open the super_block at the default location
* and as read-write.
*/
root = open_ctree(dev, 0, OPEN_CTREE_WRITES);
if (!root) /* errors are printed by open_ctree() */
return -1;
trans = btrfs_start_transaction(root, 1);
BUG_ON(IS_ERR(trans));
__strncpy_null(root->fs_info->super_copy->label, label, BTRFS_LABEL_SIZE - 1);
btrfs_commit_transaction(trans, root);
/* Now we close it since we are done. */
close_ctree(root);
return 0;
}
static int set_label_mounted(const char *mount_path, const char *labelp)
{
int fd;
char label[BTRFS_LABEL_SIZE];
fd = open(mount_path, O_RDONLY | O_NOATIME);
if (fd < 0) {
error("unable to access %s: %m", mount_path);
return -1;
}
memset(label, 0, sizeof(label));
__strncpy_null(label, labelp, BTRFS_LABEL_SIZE - 1);
if (ioctl(fd, BTRFS_IOC_SET_FSLABEL, label) < 0) {
error("unable to set label of %s: %m", mount_path);
close(fd);
return -1;
}
close(fd);
return 0;
}
int get_label_unmounted(const char *dev, char *label)
{
struct btrfs_root *root;
int ret;
ret = check_mounted(dev);
if (ret < 0) {
error("checking mount status of %s failed: %d", dev, ret);
return -1;
}
/* Open the super_block at the default location
* and as read-only.
*/
root = open_ctree(dev, 0, 0);
if(!root)
return -1;
__strncpy_null(label, root->fs_info->super_copy->label,
BTRFS_LABEL_SIZE - 1);
/* Now we close it since we are done. */
close_ctree(root);
return 0;
}
/*
* If a partition is mounted, try to get the filesystem label via its
* mounted path rather than device. Return the corresponding error
* the user specified the device path.
*/
int get_label_mounted(const char *mount_path, char *labelp)
{
char label[BTRFS_LABEL_SIZE];
int fd;
int ret;
fd = open(mount_path, O_RDONLY | O_NOATIME);
if (fd < 0) {
error("unable to access %s: %m", mount_path);
return -1;
}
memset(label, '\0', sizeof(label));
ret = ioctl(fd, BTRFS_IOC_GET_FSLABEL, label);
if (ret < 0) {
if (errno != ENOTTY)
error("unable to get label of %s: %m", mount_path);
ret = -errno;
close(fd);
return ret;
}
__strncpy_null(labelp, label, BTRFS_LABEL_SIZE - 1);
close(fd);
return 0;
}
int get_label(const char *btrfs_dev, char *label)
{
int ret;
ret = path_is_reg_or_block_device(btrfs_dev);
if (!ret)
ret = get_label_mounted(btrfs_dev, label);
else if (ret > 0)
ret = get_label_unmounted(btrfs_dev, label);
return ret;
}
int set_label(const char *btrfs_dev, const char *label)
{
int ret;
if (check_label(label))
return -1;
ret = path_is_reg_or_block_device(btrfs_dev);
if (!ret)
ret = set_label_mounted(btrfs_dev, label);
else if (ret > 0)
ret = set_label_unmounted(btrfs_dev, label);
return ret;
}
/*
* A not-so-good version fls64. No fascinating optimization since
* no one except parse_size_from_string uses it
*/
static int fls64(u64 x)
{
int i;
for (i = 0; i <64; i++)
if (x << i & (1ULL << 63))
return 64 - i;
return 64 - i;
}
u64 parse_size_from_string(const char *s)
{
char c;
char *endptr;
u64 mult = 1;
u64 ret;
if (!s) {
error("size value is empty");
exit(1);
}
if (s[0] == '-') {
error("size value '%s' is less equal than 0", s);
exit(1);
}
ret = strtoull(s, &endptr, 10);
if (endptr == s) {
error("size value '%s' is invalid", s);
exit(1);
}
if (endptr[0] && endptr[1]) {
error("illegal suffix contains character '%c' in wrong position",
endptr[1]);
exit(1);
}
/*
* strtoll returns LLONG_MAX when overflow, if this happens,
* need to call strtoull to get the real size
*/
if (errno == ERANGE && ret == ULLONG_MAX) {
error("size value '%s' is too large for u64", s);
exit(1);
}
if (endptr[0]) {
c = tolower(endptr[0]);
switch (c) {
case 'e':
mult *= 1024;
/* fallthrough */
case 'p':
mult *= 1024;
/* fallthrough */
case 't':
mult *= 1024;
/* fallthrough */
case 'g':
mult *= 1024;
/* fallthrough */
case 'm':
mult *= 1024;
/* fallthrough */
case 'k':
mult *= 1024;
/* fallthrough */
case 'b':
break;
default:
error("unknown size descriptor '%c'", c);
exit(1);
}
}
/* Check whether ret * mult overflow */
if (fls64(ret) + fls64(mult) - 1 > 64) {
error("size value '%s' is too large for u64", s);
exit(1);
}
ret *= mult;
return ret;
}
u64 parse_qgroupid(const char *p)
{
char *s = strchr(p, '/');
const char *ptr_src_end = p + strlen(p);
char *ptr_parse_end = NULL;
enum btrfs_util_error err;
u64 level;
u64 id;
int fd;
int ret = 0;
if (p[0] == '/')
goto path;
/* Numeric format like '0/257' is the primary case */
if (!s) {
id = strtoull(p, &ptr_parse_end, 10);
if (ptr_parse_end != ptr_src_end)
goto path;
return id;
}
level = strtoull(p, &ptr_parse_end, 10);
if (ptr_parse_end != s)
goto path;
id = strtoull(s + 1, &ptr_parse_end, 10);
if (ptr_parse_end != ptr_src_end)
goto path;
return (level << BTRFS_QGROUP_LEVEL_SHIFT) | id;
path:
/* Path format like subv at 'my_subvol' is the fallback case */
err = btrfs_util_is_subvolume(p);
if (err)
goto err;
fd = open(p, O_RDONLY);
if (fd < 0)
goto err;
ret = lookup_path_rootid(fd, &id);
if (ret) {
errno = -ret;
error("failed to lookup root id: %m");
}
close(fd);
if (ret < 0)
goto err;
return id;
err:
error("invalid qgroupid or subvolume path: %s", p);
exit(-1);
}
enum btrfs_csum_type parse_csum_type(const char *s)
{
if (strcasecmp(s, "crc32c") == 0) {
return BTRFS_CSUM_TYPE_CRC32;
} else if (strcasecmp(s, "xxhash64") == 0 ||
strcasecmp(s, "xxhash") == 0) {
return BTRFS_CSUM_TYPE_XXHASH;
} else if (strcasecmp(s, "sha256") == 0) {
return BTRFS_CSUM_TYPE_SHA256;
} else if (strcasecmp(s, "blake2b") == 0 ||
strcasecmp(s, "blake2") == 0) {
return BTRFS_CSUM_TYPE_BLAKE2;
} else {
error("unknown csum type %s", s);
exit(1);
}
/* not reached */
return 0;
}
int get_device_info(int fd, u64 devid,
struct btrfs_ioctl_dev_info_args *di_args)
{
int ret;
di_args->devid = devid;
memset(&di_args->uuid, '\0', sizeof(di_args->uuid));
ret = ioctl(fd, BTRFS_IOC_DEV_INFO, di_args);
return ret < 0 ? -errno : 0;
}
int get_df(int fd, struct btrfs_ioctl_space_args **sargs_ret)
{
u64 count = 0;
int ret;
struct btrfs_ioctl_space_args *sargs;
sargs = malloc(sizeof(struct btrfs_ioctl_space_args));
if (!sargs)
return -ENOMEM;
sargs->space_slots = 0;
sargs->total_spaces = 0;
ret = ioctl(fd, BTRFS_IOC_SPACE_INFO, sargs);
if (ret < 0) {
error("cannot get space info: %m");
free(sargs);
return -errno;
}
/* This really should never happen */
if (!sargs->total_spaces) {
free(sargs);
return -ENOENT;
}
count = sargs->total_spaces;
free(sargs);
sargs = malloc(sizeof(struct btrfs_ioctl_space_args) +
(count * sizeof(struct btrfs_ioctl_space_info)));
if (!sargs)
return -ENOMEM;
sargs->space_slots = count;
sargs->total_spaces = 0;
ret = ioctl(fd, BTRFS_IOC_SPACE_INFO, sargs);
if (ret < 0) {
error("cannot get space info with %llu slots: %m",
count);
free(sargs);
return -errno;
}
*sargs_ret = sargs;
return 0;
}
static u64 find_max_device_id(struct btrfs_ioctl_search_args *search_args,
int nr_items)
{
struct btrfs_dev_item *dev_item;
char *buf = search_args->buf;
buf += (nr_items - 1) * (sizeof(struct btrfs_ioctl_search_header)
+ sizeof(struct btrfs_dev_item));
buf += sizeof(struct btrfs_ioctl_search_header);
dev_item = (struct btrfs_dev_item *)buf;
return btrfs_stack_device_id(dev_item);
}
static int search_chunk_tree_for_fs_info(int fd,
struct btrfs_ioctl_fs_info_args *fi_args)
{
int ret;
int max_items;
u64 start_devid = 1;
struct btrfs_ioctl_search_args search_args;
struct btrfs_ioctl_search_key *search_key = &search_args.key;
fi_args->num_devices = 0;
max_items = BTRFS_SEARCH_ARGS_BUFSIZE
/ (sizeof(struct btrfs_ioctl_search_header)
+ sizeof(struct btrfs_dev_item));
search_key->tree_id = BTRFS_CHUNK_TREE_OBJECTID;
search_key->min_objectid = BTRFS_DEV_ITEMS_OBJECTID;
search_key->max_objectid = BTRFS_DEV_ITEMS_OBJECTID;
search_key->min_type = BTRFS_DEV_ITEM_KEY;
search_key->max_type = BTRFS_DEV_ITEM_KEY;
search_key->min_transid = 0;
search_key->max_transid = (u64)-1;
search_key->nr_items = max_items;
search_key->max_offset = (u64)-1;
again:
search_key->min_offset = start_devid;
ret = ioctl(fd, BTRFS_IOC_TREE_SEARCH, &search_args);
if (ret < 0)
return -errno;
fi_args->num_devices += (u64)search_key->nr_items;
if (search_key->nr_items == max_items) {
start_devid = find_max_device_id(&search_args,
search_key->nr_items) + 1;
goto again;
}
/* Get the latest max_id to stay consistent with the num_devices */
if (search_key->nr_items == 0)
/*
* last tree_search returns an empty buf, use the devid of
* the last dev_item of the previous tree_search
*/
fi_args->max_id = start_devid - 1;
else
fi_args->max_id = find_max_device_id(&search_args,
search_key->nr_items);
return 0;
}
/*
* For a given path, fill in the ioctl fs_ and info_ args.
* If the path is a btrfs mountpoint, fill info for all devices.
* If the path is a btrfs device, fill in only that device.
*
* The path provided must be either on a mounted btrfs fs,
* or be a mounted btrfs device.
*
* Returns 0 on success, or a negative errno.
*/
int get_fs_info(const char *path, struct btrfs_ioctl_fs_info_args *fi_args,
struct btrfs_ioctl_dev_info_args **di_ret)
{
int fd = -1;
int ret = 0;
int ndevs = 0;
u64 last_devid = 0;
int replacing = 0;
struct btrfs_fs_devices *fs_devices_mnt = NULL;
struct btrfs_ioctl_dev_info_args *di_args;
struct btrfs_ioctl_dev_info_args tmp;
char mp[PATH_MAX];
DIR *dirstream = NULL;
memset(fi_args, 0, sizeof(*fi_args));
if (path_is_block_device(path) == 1) {
struct btrfs_super_block *disk_super;
char buf[BTRFS_SUPER_INFO_SIZE];
/* Ensure it's mounted, then set path to the mountpoint */
fd = open(path, O_RDONLY);
if (fd < 0) {
ret = -errno;
error("cannot open %s: %m", path);
goto out;
}
ret = check_mounted_where(fd, path, mp, sizeof(mp),
&fs_devices_mnt, SBREAD_DEFAULT);
if (!ret) {
ret = -EINVAL;
goto out;
}
if (ret < 0)
goto out;
path = mp;
/* Only fill in this one device */
fi_args->num_devices = 1;
disk_super = (struct btrfs_super_block *)buf;
ret = btrfs_read_dev_super(fd, disk_super,
BTRFS_SUPER_INFO_OFFSET, 0);
if (ret < 0) {
ret = -EIO;
goto out;
}
last_devid = btrfs_stack_device_id(&disk_super->dev_item);
fi_args->max_id = last_devid;
memcpy(fi_args->fsid, fs_devices_mnt->fsid, BTRFS_FSID_SIZE);
close(fd);
}
/* at this point path must not be for a block device */
fd = open_file_or_dir(path, &dirstream);
if (fd < 0) {
ret = -errno;
goto out;
}
/* fill in fi_args if not just a single device */
if (fi_args->num_devices != 1) {
ret = ioctl(fd, BTRFS_IOC_FS_INFO, fi_args);
if (ret < 0) {
ret = -errno;
goto out;
}
/*
* The fs_args->num_devices does not include seed devices
*/
ret = search_chunk_tree_for_fs_info(fd, fi_args);
if (ret)
goto out;
/*
* search_chunk_tree_for_fs_info() will lacks the devid 0
* so manual probe for it here.
*/
ret = get_device_info(fd, 0, &tmp);
if (!ret) {
fi_args->num_devices++;
ndevs++;
replacing = 1;
if (last_devid == 0)
last_devid++;
}
}
if (!fi_args->num_devices)
goto out;
di_args = *di_ret = malloc((fi_args->num_devices) * sizeof(*di_args));
if (!di_args) {
ret = -errno;
goto out;
}
if (replacing)
memcpy(di_args, &tmp, sizeof(tmp));
for (; last_devid <= fi_args->max_id && ndevs < fi_args->num_devices;
last_devid++) {
ret = get_device_info(fd, last_devid, &di_args[ndevs]);
if (ret == -ENODEV)
continue;
if (ret)
goto out;
ndevs++;
}
/*
* only when the only dev we wanted to find is not there then
* let any error be returned
*/
if (fi_args->num_devices != 1) {
BUG_ON(ndevs == 0);
ret = 0;
}
out:
close_file_or_dir(fd, dirstream);
return ret;
}
int get_fsid_fd(int fd, u8 *fsid)
{
int ret;
struct btrfs_ioctl_fs_info_args args;
ret = ioctl(fd, BTRFS_IOC_FS_INFO, &args);
if (ret < 0)
return -errno;
memcpy(fsid, args.fsid, BTRFS_FSID_SIZE);
return 0;
}
int get_fsid(const char *path, u8 *fsid, int silent)
{
int ret;
int fd;
fd = open(path, O_RDONLY);
if (fd < 0) {
if (!silent)
error("failed to open %s: %m", path);
return -errno;
}
ret = get_fsid_fd(fd, fsid);
close(fd);
return ret;
}
static int group_profile_devs_min(u64 flag)
{
switch (flag & BTRFS_BLOCK_GROUP_PROFILE_MASK) {
case 0: /* single */
case BTRFS_BLOCK_GROUP_DUP:
return 1;
case BTRFS_BLOCK_GROUP_RAID0:
case BTRFS_BLOCK_GROUP_RAID1:
case BTRFS_BLOCK_GROUP_RAID5:
return 2;
case BTRFS_BLOCK_GROUP_RAID6:
case BTRFS_BLOCK_GROUP_RAID1C3:
return 3;
case BTRFS_BLOCK_GROUP_RAID10:
case BTRFS_BLOCK_GROUP_RAID1C4:
return 4;
default:
return -1;
}
}
int test_num_disk_vs_raid(u64 metadata_profile, u64 data_profile,
u64 dev_cnt, int mixed, int ssd)
{
u64 allowed = 0;
u64 profile = metadata_profile | data_profile;
switch (dev_cnt) {
default:
case 4:
allowed |= BTRFS_BLOCK_GROUP_RAID10;
allowed |= BTRFS_BLOCK_GROUP_RAID10 | BTRFS_BLOCK_GROUP_RAID1C4;
/* fallthrough */
case 3:
allowed |= BTRFS_BLOCK_GROUP_RAID6 | BTRFS_BLOCK_GROUP_RAID1C3;
/* fallthrough */
case 2:
allowed |= BTRFS_BLOCK_GROUP_RAID0 | BTRFS_BLOCK_GROUP_RAID1 |
BTRFS_BLOCK_GROUP_RAID5;
/* fallthrough */
case 1:
allowed |= BTRFS_BLOCK_GROUP_DUP;
}
if (dev_cnt > 1 && profile & BTRFS_BLOCK_GROUP_DUP) {
warning("DUP is not recommended on filesystem with multiple devices");
}
if (metadata_profile & ~allowed) {
fprintf(stderr,
"ERROR: unable to create FS with metadata profile %s "
"(have %llu devices but %d devices are required)\n",
btrfs_group_profile_str(metadata_profile), dev_cnt,
group_profile_devs_min(metadata_profile));
return 1;
}
if (data_profile & ~allowed) {
fprintf(stderr,
"ERROR: unable to create FS with data profile %s "
"(have %llu devices but %d devices are required)\n",
btrfs_group_profile_str(data_profile), dev_cnt,
group_profile_devs_min(data_profile));
return 1;
}
if (dev_cnt == 3 && profile & BTRFS_BLOCK_GROUP_RAID6) {
warning("RAID6 is not recommended on filesystem with 3 devices only");
}
if (dev_cnt == 2 && profile & BTRFS_BLOCK_GROUP_RAID5) {
warning("RAID5 is not recommended on filesystem with 2 devices only");
}
warning_on(!mixed && (data_profile & BTRFS_BLOCK_GROUP_DUP) && ssd,
"DUP may not actually lead to 2 copies on the device, see manual page");
return 0;
}
int group_profile_max_safe_loss(u64 flags)
{
switch (flags & BTRFS_BLOCK_GROUP_PROFILE_MASK) {
case 0: /* single */
case BTRFS_BLOCK_GROUP_DUP:
case BTRFS_BLOCK_GROUP_RAID0:
return 0;
case BTRFS_BLOCK_GROUP_RAID1:
case BTRFS_BLOCK_GROUP_RAID5:
case BTRFS_BLOCK_GROUP_RAID10:
return 1;
case BTRFS_BLOCK_GROUP_RAID6:
case BTRFS_BLOCK_GROUP_RAID1C3:
return 2;
case BTRFS_BLOCK_GROUP_RAID1C4:
return 3;
default:
return -1;
}
}
/*
* This reads a line from the stdin and only returns non-zero if the
* first whitespace delimited token is a case insensitive match with yes
* or y.
*/
int ask_user(const char *question)
{
char buf[30] = {0,};
char *saveptr = NULL;
char *answer;
printf("%s [y/N]: ", question);
return fgets(buf, sizeof(buf) - 1, stdin) &&
(answer = strtok_r(buf, " \t\n\r", &saveptr)) &&
(!strcasecmp(answer, "yes") || !strcasecmp(answer, "y"));
}
/*
* Partial representation of a line in /proc/pid/mountinfo
*/
struct mnt_entry {
const char *root;
const char *path;
const char *options1;
const char *fstype;
const char *device;
const char *options2;
};
/*
* Find first occurence of up an option string (as "option=") in @options,
* separated by comma. Return allocated string as "option=value"
*/
static char *find_option(const char *options, const char *option)
{
char *tmp, *ret;
tmp = strstr(options, option);
if (!tmp)
return NULL;
ret = strdup(tmp);
tmp = ret;
while (*tmp && *tmp != ',')
tmp++;
*tmp = 0;
return ret;
}
/* Match whitespace separator */
static bool is_sep(char c)
{
return c == ' ' || c == '\t';
}
/* Advance @line skipping over all non-separator chars */
static void skip_nonsep(char **line)
{
while (**line && !is_sep(**line))
(*line)++;
}
/* Advance @line skipping over all separator chars, setting them to nul char */
static void skip_sep(char **line)
{
while (**line && is_sep(**line)) {
**line = 0;
(*line)++;
}
}
static bool isoctal(char c)
{
return '0' <= c && c <= '7';
}
/*
* Validate complete escape sequence used for mangling special chars in paths,
* eg. \012 == 10 == 0xa == '\n'.
* Mandatory format: backslash and 3 octal digits.
*/
static bool valid_escape(const char *str)
{
if (*str == 0 || *str != '\\')
return false;
str++;
if (*str == 0 || is_sep(*str) || !isoctal(*str))
return false;
str++;
if (*str == 0 || is_sep(*str) || !isoctal(*str))
return false;
str++;
if (*str == 0 || is_sep(*str) || !isoctal(*str))
return false;
return true;
}
/*
* Read a path from @line, with potentially mangled special characters.
* - the input is changed in-place when unmangling is done
* - end of path is a space character (a valid space in the path is mangled)
* - line is advanced to the final separator or nul character
* - returned path is a valid string terminated by zero or whitespace separator
*/
char *read_path(char **line)
{
char *ret = *line;
char *out = *line;
while (**line) {
if (is_sep(**line))
break;
if (valid_escape(*line)) {
char c;
(*line)++;
c = ((*(*line)++) & 0b111) << 6;
c |= ((*(*line)++) & 0b111) << 3;
c |= ((*(*line)++) & 0b111);
*out++ = c;
} else {
*out++ = *(*line)++;
}
}
/*
* Unmangled characters make the final string shorter, add the null
* terminator. Otherwise keep the line at the space separator so
* followup parsing can continue.
*/
if (out < *line)
*out = 0;
return ret;
}
/*
* Parse a line from /proc/pid/mountinfo
* Example:
272 265 0:49 /subvol /mnt/path rw,noatime shared:145 - btrfs /dev/sda1 rw,subvolid=5598,subvol=/subvol
0 1 2 3 4 5 6 7 8 9 10
* Fields related to paths and options are parsed, @line is changed in place,
* separators are replaced by nul char, paths could be unmangled.
*/
static void parse_mntinfo_line(char *line, struct mnt_entry *ent)
{
/* Skip 0 */
skip_nonsep(&line);
skip_sep(&line);
/* Skip 1 */
skip_nonsep(&line);
skip_sep(&line);
/* Skip 2 */
skip_nonsep(&line);
skip_sep(&line);
/* Read 3 */
ent->root = read_path(&line);
skip_sep(&line);
/* Read 4 */
ent->path = read_path(&line);
skip_sep(&line);
/* Read 5 */
ent->options1 = line;
skip_nonsep(&line);
skip_sep(&line);
/* Skip 6 */
skip_nonsep(&line);
skip_sep(&line);
/* Skip 7 */
skip_nonsep(&line);
skip_sep(&line);
/* Read 8 */
ent->fstype = line;
skip_nonsep(&line);
skip_sep(&line);
/* Read 9 */
ent->device = read_path(&line);
skip_sep(&line);
/* Read 10 */
ent->options2 = line;
skip_nonsep(&line);
skip_sep(&line);
}
/*
* Compare the subvolume passed with the pathname of the directory mounted in
* btrfs. The pathname inside btrfs is different from getmnt and friends, since
* it can detect bind mounts to content from the inside of the original mount.
*
* Example:
* # mount -o subvol=/vol /dev/sda2 /mnt
* # mount --bind /mnt/dir2 /othermnt
*
* # mounts
* ...
* /dev/sda2 on /mnt type btrfs (ro,relatime,ssd,space_cache,subvolid=256,subvol=/vol)
* /dev/sda2 on /othermnt type btrfs (ro,relatime,ssd,space_cache,subvolid=256,subvol=/vol)
*
* # cat /proc/self/mountinfo
*
* 38 30 0:32 /vol /mnt ro,relatime - btrfs /dev/sda2 ro,ssd,space_cache,subvolid=256,subvol=/vol
* 37 29 0:32 /vol/dir2 /othermnt ro,relatime - btrfs /dev/sda2 ro,ssd,space_cache,subvolid=256,subvol=/vol
*
* If we try to find a mount point only using subvol and subvolid from mount
* options we would get mislead to belive that /othermnt has the same content
* as /mnt.
*
* But, using mountinfo, we have the pathaname _inside_ the filesystem, so we
* can filter out the mount points with bind mounts which have different content
* from the original mounts, in this case the mount point with id 37.
*/
int find_mount_fsroot(const char *subvol, const char *subvolid, char **mount)
{
FILE *mnt;
char *buf = NULL;
int bs = 4096;
int line = 0;
int ret = 0;
bool found = false;
mnt = fopen("/proc/self/mountinfo", "r");
if (!mnt)
return -1;