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mount: add plain mountpoints

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This is a preparation of mounts-v2 new algorithm for mount restore, we
add an alternative mountpoints to each mount, so that if we mount mounts
in these mountpoints they will be "plain": each mount in separate
sub-directory of root_yard, mounts will be mounted without tree. Tree
reconstruction will be done in separate step.

Cherry-picked from Virtuozzo criu:
https://src.openvz.org/projects/OVZ/repos/criu/commits/5e6de171a

Changes: improve get_plain_mountpoint().

Signed-off-by: Pavel Tikhomirov <ptikhomirov@virtuozzo.com>
This commit is contained in:
Pavel Tikhomirov 2020-05-28 11:30:16 +03:00 committed by Andrei Vagin
parent f2d1c7fab8
commit f032741cd6
2 changed files with 42 additions and 0 deletions
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3
criu/include/mount.h
View File

@ -48,6 +48,7 @@ struct mount_info {
*/
char *mountpoint;
char *ns_mountpoint;
char *plain_mountpoint;
int fd;
unsigned flags;
unsigned sb_flags;
@ -168,6 +169,8 @@ extern int read_mnt_ns_img(void);
extern void cleanup_mnt_ns(void);
extern void clean_cr_time_mounts(void);
extern char *get_plain_mountpoint(int mnt_id, char *name);
extern bool add_skip_mount(const char *mountpoint);
struct ns_id;
extern int get_sdev_from_fd(int fd, unsigned int *sdev, bool parse_mountinfo);

39
criu/mount.c
View File

@ -49,6 +49,10 @@ static LIST_HEAD(delayed_unbindable);
char *service_mountpoint(const struct mount_info *mi)
{
if (!opts.mntns_compat_mode && opts.mode == CR_RESTORE) {
BUG_ON(!mi->plain_mountpoint);
return mi->plain_mountpoint;
}
return mi->mountpoint;
}
@ -1627,6 +1631,28 @@ err:
return -1;
}
/*
* Helper for getting a path to mount's plain mountpoint
*/
char *get_plain_mountpoint(int mnt_id, char *name)
{
static char tmp[PATH_MAX];
int ret;
if (!mnt_roots)
return NULL;
if (name)
ret = snprintf(tmp, sizeof(tmp), "%s/mnt-%s", mnt_roots, name);
else
ret = snprintf(tmp, sizeof(tmp), "%s/mnt-%010d", mnt_roots, mnt_id);
if (ret >= sizeof(tmp))
return NULL;
return xstrdup(tmp);
}
static __maybe_unused struct mount_info *add_cr_time_mount(struct mount_info *root, char *fsname, const char *path,
unsigned int s_dev, bool rst)
{
@ -1654,6 +1680,11 @@ static __maybe_unused struct mount_info *add_cr_time_mount(struct mount_info *ro
sprintf(mi->mountpoint, "%s%s", root->mountpoint, path);
else
sprintf(mi->mountpoint, "%s/%s", root->mountpoint, path);
if (rst) {
mi->plain_mountpoint = get_plain_mountpoint(-1, "crtime");
if (!mi->plain_mountpoint)
goto err;
}
mi->mnt_id = HELPER_MNT_ID;
mi->flags = mi->sb_flags = 0;
mi->root = xstrdup("/");
@ -2995,6 +3026,7 @@ void mnt_entry_free(struct mount_info *mi)
if (mi) {
xfree(mi->root);
xfree(mi->mountpoint);
xfree(mi->plain_mountpoint);
xfree(mi->source);
xfree(mi->options);
xfree(mi->fsname);
@ -3120,6 +3152,10 @@ static int get_mp_mountpoint(char *mountpoint, struct mount_info *mi, char *root
mi->ns_mountpoint = mi->mountpoint + root_len;
mi->plain_mountpoint = get_plain_mountpoint(mi->mnt_id, NULL);
if (!mi->plain_mountpoint)
return -1;
pr_debug("\t\tWill mount %d @ %s %s\n", mi->mnt_id, service_mountpoint(mi), mi->ns_mountpoint);
return 0;
}
@ -3293,6 +3329,9 @@ static int merge_mount_trees(void)
return -1;
root_yard_mp->mountpoint = mnt_roots;
root_yard_mp->plain_mountpoint = xstrdup(mnt_roots);
if (!root_yard_mp->plain_mountpoint)
return -1;
root_yard_mp->mounted = true;
root_yard_mp->mnt_bind_is_populated = true;
root_yard_mp->is_overmounted = false;