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mnt: In umount_tree reuse mnt_list instead of mnt_hash

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umount_tree builds a list of mounts that need to be unmounted.
Utilize mnt_list for this purpose instead of mnt_hash.  This begins to
allow keeping a mount on the mnt_hash after it is unmounted, which is
necessary for a properly functioning MNT_LOCKED implementation.

The fact that mnt_list is an ordinary list makding available list_move
is nice bonus.

Cc: stable@vger.kernel.org
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
This commit is contained in:
Eric W. Biederman 2014-12-18 13:10:48 -06:00
parent 8318e667f1
commit c003b26ff9
3 changed files with 15 additions and 13 deletions
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20
fs/namespace.c
View File

@ -1327,23 +1327,25 @@ enum umount_tree_flags {
*/ */
static void umount_tree(struct mount *mnt, enum umount_tree_flags how) static void umount_tree(struct mount *mnt, enum umount_tree_flags how)
{ {
HLIST_HEAD(tmp_list); LIST_HEAD(tmp_list);
struct mount *p; struct mount *p;
for (p = mnt; p; p = next_mnt(p, mnt)) { /* Gather the mounts to umount */
for (p = mnt; p; p = next_mnt(p, mnt))
list_move(&p->mnt_list, &tmp_list);
/* Hide the mounts from lookup_mnt and mnt_mounts */
list_for_each_entry(p, &tmp_list, mnt_list) {
hlist_del_init_rcu(&p->mnt_hash); hlist_del_init_rcu(&p->mnt_hash);
hlist_add_head(&p->mnt_hash, &tmp_list); list_del_init(&p->mnt_child);
} }
hlist_for_each_entry(p, &tmp_list, mnt_hash) /* Add propogated mounts to the tmp_list */
list_del_init(&p->mnt_child);
if (how & UMOUNT_PROPAGATE) if (how & UMOUNT_PROPAGATE)
propagate_umount(&tmp_list); propagate_umount(&tmp_list);
while (!hlist_empty(&tmp_list)) { while (!list_empty(&tmp_list)) {
p = hlist_entry(tmp_list.first, struct mount, mnt_hash); p = list_first_entry(&tmp_list, struct mount, mnt_list);
hlist_del_init_rcu(&p->mnt_hash);
list_del_init(&p->mnt_expire); list_del_init(&p->mnt_expire);
list_del_init(&p->mnt_list); list_del_init(&p->mnt_list);
__touch_mnt_namespace(p->mnt_ns); __touch_mnt_namespace(p->mnt_ns);

6
fs/pnode.c
View File

@ -384,7 +384,7 @@ static void __propagate_umount(struct mount *mnt)
if (child && list_empty(&child->mnt_mounts)) { if (child && list_empty(&child->mnt_mounts)) {
list_del_init(&child->mnt_child); list_del_init(&child->mnt_child);
hlist_del_init_rcu(&child->mnt_hash); hlist_del_init_rcu(&child->mnt_hash);
hlist_add_before_rcu(&child->mnt_hash, &mnt->mnt_hash); list_move_tail(&child->mnt_list, &mnt->mnt_list);
} }
} }
} }
@ -396,11 +396,11 @@ static void __propagate_umount(struct mount *mnt)
* *
* vfsmount lock must be held for write * vfsmount lock must be held for write
*/ */
int propagate_umount(struct hlist_head *list) int propagate_umount(struct list_head *list)
{ {
struct mount *mnt; struct mount *mnt;
hlist_for_each_entry(mnt, list, mnt_hash) list_for_each_entry(mnt, list, mnt_list)
__propagate_umount(mnt); __propagate_umount(mnt);
return 0; return 0;
} }

2
fs/pnode.h
View File

@ -40,7 +40,7 @@ static inline void set_mnt_shared(struct mount *mnt)
void change_mnt_propagation(struct mount *, int); void change_mnt_propagation(struct mount *, int);
int propagate_mnt(struct mount *, struct mountpoint *, struct mount *, int propagate_mnt(struct mount *, struct mountpoint *, struct mount *,
struct hlist_head *); struct hlist_head *);
int propagate_umount(struct hlist_head *); int propagate_umount(struct list_head *);
int propagate_mount_busy(struct mount *, int); int propagate_mount_busy(struct mount *, int);
void mnt_release_group_id(struct mount *); void mnt_release_group_id(struct mount *);
int get_dominating_id(struct mount *mnt, const struct path *root); int get_dominating_id(struct mount *mnt, const struct path *root);