mir/criu
2
0
Fork 0
mirror of https://github.com/checkpoint-restore/criu synced 2025-08-30 22:05:36 +00:00
Code Issues Releases Wiki Activity

mount: make mnt_resort_siblings nonrecursive and reuse friendly

Browse Source 
Add mnt_subtree_next DFS-next search to remove recursion.

v5: add these patch, remove recursion from sorting helpers
v6: rip out butifull yet unused step-part of nfs-next algorithm

Signed-off-by: Pavel Tikhomirov <ptikhomirov@virtuozzo.com>
This commit is contained in:
Pavel Tikhomirov
2019-06-27 12:43:40 +03:00
committed by Andrei Vagin
parent 35adc08598
commit f3cca97d80
1 changed files with 48 additions and 9 deletions
Download Patch File Download Diff File Expand all files Collapse all files

57
criu/mount.c
View File

@@ -385,13 +385,12 @@ static unsigned int mnt_depth(struct mount_info *m)
return depth;
}
static void mnt_resort_siblings(struct mount_info *tree)
static void __mnt_resort_children(struct mount_info *parent)
{
struct mount_info *m, *p;
LIST_HEAD(list);
/*
* Put siblings of each node in an order they can be (u)mounted
* Put children mounts in an order they can be (u)mounted
* I.e. if we have mounts on foo/bar/, foo/bar/foobar/ and foo/
* we should put them in the foo/bar/foobar/, foo/bar/, foo/ order.
* Otherwise we will not be able to (u)mount them in a sequence.
@@ -403,11 +402,12 @@ static void mnt_resort_siblings(struct mount_info *tree)
* to contain hundreds (or more) elements.
*/
pr_info("\tResorting siblings on %d\n", tree->mnt_id);
while (!list_empty(&tree->children)) {
pr_info("\tResorting children of %d in mount order\n", parent->mnt_id);
while (!list_empty(&parent->children)) {
struct mount_info *m, *p;
unsigned int depth;
m = list_first_entry(&tree->children, struct mount_info, siblings);
m = list_first_entry(&parent->children, struct mount_info, siblings);
list_del(&m->siblings);
depth = mnt_depth(m);
@@ -416,10 +416,31 @@ static void mnt_resort_siblings(struct mount_info *tree)
break;
list_add_tail(&m->siblings, &p->siblings);
mnt_resort_siblings(m);
}
list_splice(&list, &tree->children);
list_splice(&list, &parent->children);
}
static struct mount_info *mnt_subtree_next(struct mount_info *mi,
struct mount_info *root);
static void resort_siblings(struct mount_info *root,
void (*resort_children)(struct mount_info *)) {
struct mount_info *mi = root;
while (1) {
/*
* Explanation: sorting the children of the tree like these is
* safe and does not break the tree search in mnt_subtree_next
* (DFS-next search), as we sort children before calling next
* on parent and thus before DFS-next ever touches them, so
* from the perspective of DFS-next all children look like they
* are already sorted.
*/
resort_children(mi);
mi = mnt_subtree_next(mi, root);
if (!mi)
break;
}
}
static void mnt_tree_show(struct mount_info *tree, int off)
@@ -980,7 +1001,7 @@ static struct mount_info *mnt_build_tree(struct mount_info *list)
if (!tree)
return NULL;
mnt_resort_siblings(tree);
resort_siblings(tree, __mnt_resort_children);
pr_info("Done:\n");
mnt_tree_show(tree, 0);
return tree;
@@ -3821,3 +3842,21 @@ int remount_readonly_mounts(void)
*/
return call_helper_process(ns_remount_readonly_mounts, NULL);
}
static struct mount_info *mnt_subtree_next(struct mount_info *mi,
struct mount_info *root)
{
if (!list_empty(&mi->children))
return list_entry(mi->children.next,
struct mount_info, siblings);
while (mi->parent && mi != root) {
if (mi->siblings.next == &mi->parent->children)
mi = mi->parent;
else
return list_entry(mi->siblings.next,
struct mount_info, siblings);
}
return NULL;
}