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mnt: Handle external bind mounts according to --ext-mount option (v3)

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Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
This commit is contained in:
Pavel Emelyanov 2014-06-09 17:26:59 +04:00
parent c7e0042946
commit 061d6cfadf
2 changed files with 85 additions and 11 deletions
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95
mount.c
View file

@ -63,6 +63,18 @@ int ext_mount_add(char *key, char *val)
return 0;
}
/* Lookup ext_mount by key field */
static struct ext_mount *ext_mount_lookup(char *key)
{
struct ext_mount *em;
list_for_each_entry(em, &opts.ext_mounts, l)
if (!strcmp(em->key, key))
return em;
return NULL;
}
/*
* Single linked list of mount points get from proc/images
*/
@ -342,6 +354,20 @@ static void mnt_tree_show(struct mount_info *tree, int off)
pr_info("%*s<--\n", off, "");
}
static int try_resolve_ext_mount(struct mount_info *info)
{
struct ext_mount *em;
em = ext_mount_lookup(info->mountpoint + 1 /* trim the . */);
if (em == NULL)
return -ENOTSUP;
pr_info("Found %s mapping for %s mountpoint\n",
em->val, info->mountpoint);
info->external = em;
return 0;
}
static int validate_mounts(struct mount_info *info, bool for_dump)
{
struct mount_info *m, *t;
@ -403,11 +429,14 @@ static int validate_mounts(struct mount_info *info, bool for_dump)
ret = cr_plugin_dump_ext_mount(m->mountpoint + 1, m->mnt_id);
if (ret == 0)
m->need_plugin = true;
else if (ret == -ENOTSUP)
ret = try_resolve_ext_mount(m);
} else {
if (m->need_plugin)
if (m->need_plugin || m->external)
/*
* plugin should take care of this one
* in restore_ext_mount
* in restore_ext_mount, or do_bind_mount
* will mount it as external
*/
ret = 0;
else
@ -908,7 +937,6 @@ static int dump_one_mountpoint(struct mount_info *pm, int fd)
me.root_dev = pm->s_dev;
me.parent_mnt_id = pm->parent_mnt_id;
me.flags = pm->flags;
me.root = pm->root;
me.mountpoint = pm->mountpoint + 1;
me.source = pm->source;
me.options = strip(pm->options);
@ -921,6 +949,18 @@ static int dump_one_mountpoint(struct mount_info *pm, int fd)
me.with_plugin = true;
}
if (pm->external) {
/*
* For external mount points dump the mapping's
* value instead of root. See collect_mnt_from_image
* for reverse mapping details.
*/
me.root = pm->external->val;
me.has_ext_mount = true;
me.ext_mount = true;
} else
me.root = pm->root;
if (pb_write_one(fd, &me, PB_MNT))
return -1;
@ -1273,9 +1313,20 @@ static int do_bind_mount(struct mount_info *mi)
bool shared = mi->shared_id && mi->shared_id == mi->bind->shared_id;
if (!mi->need_plugin) {
char rpath[PATH_MAX];
char *root, rpath[PATH_MAX];
int tok = 0;
if (mi->external) {
/*
* We have / pointing to criu's ns root still,
* so just use the mapping's path. The mountpoint
* is tuned in collect_mnt_from_image to refer
* to proper location in the namespace we restore.
*/
root = mi->root;
goto do_bind;
}
/*
* Cut common part of root.
* For non-root binds the source is always "/" (checked)
@ -1290,9 +1341,10 @@ static int do_bind_mount(struct mount_info *mi)
snprintf(rpath, sizeof(rpath), "%s/%s",
mi->bind->mountpoint, mi->root + tok);
pr_info("\tBind %s to %s\n", rpath, mi->mountpoint);
if (mount(rpath, mi->mountpoint, NULL,
root = rpath;
do_bind:
pr_info("\tBind %s to %s\n", root, mi->mountpoint);
if (mount(root, mi->mountpoint, NULL,
MS_BIND, NULL) < 0) {
pr_perror("Can't mount at %s", mi->mountpoint);
return -1;
@ -1592,10 +1644,31 @@ static int collect_mnt_from_image(struct mount_info **pms, struct ns_id *nsid)
/* FIXME: abort unsupported early */
pm->fstype = decode_fstype(me->fstype);
pr_debug("\t\tGetting root for %d\n", pm->mnt_id);
pm->root = xstrdup(me->root);
if (!pm->root)
goto err;
if (me->ext_mount) {
struct ext_mount *em;
/*
* External mount point -- get the reverse mapping
* from the command line and put into root's place
*/
em = ext_mount_lookup(me->root);
if (!em) {
pr_err("No mapping for %s mountpoint\n", me->mountpoint);
goto err;
}
pm->external = em;
pm->root = em->val;
pr_debug("Mountpoint %s will have root from %s\n",
me->mountpoint, pm->root);
} else {
pr_debug("\t\tGetting root for %d\n", pm->mnt_id);
pm->root = xstrdup(me->root);
if (!pm->root)
goto err;
}
len = strlen(me->mountpoint) + root_len + 1;
pm->mountpoint = xmalloc(len);

1
protobuf/mnt.proto
View file

@ -29,4 +29,5 @@ message mnt_entry {
optional uint32 master_id = 11;
optional bool with_plugin = 12;
optional bool ext_mount = 13;
}