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switch the IO-triggering parts of umount to fs_pin

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Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Al Viro 2015-01-10 19:01:08 -05:00
parent 59eda0e07f
commit 87b95ce096
3 changed files with 20 additions and 29 deletions
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1
fs/fs_pin.c
View File

@ -1,7 +1,6 @@
#include <linux/fs.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/fs_pin.h>
#include "internal.h"
#include "mount.h"

4
fs/mount.h
View File

@ -2,6 +2,7 @@
#include <linux/seq_file.h>
#include <linux/poll.h>
#include <linux/ns_common.h>
#include <linux/fs_pin.h>
struct mnt_namespace {
atomic_t count;
@ -62,7 +63,8 @@ struct mount {
int mnt_group_id; /* peer group identifier */
int mnt_expiry_mark; /* true if marked for expiry */
struct hlist_head mnt_pins;
struct path mnt_ex_mountpoint;
struct fs_pin mnt_umount;
struct dentry *mnt_ex_mountpoint;
};
#define MNT_NS_INTERNAL ERR_PTR(-EINVAL) /* distinct from any mnt_namespace */

44
fs/namespace.c
View File

@ -190,6 +190,14 @@ unsigned int mnt_get_count(struct mount *mnt)
#endif
}
static void drop_mountpoint(struct fs_pin *p)
{
struct mount *m = container_of(p, struct mount, mnt_umount);
dput(m->mnt_ex_mountpoint);
pin_remove(p);
mntput(&m->mnt);
}
static struct mount *alloc_vfsmnt(const char *name)
{
struct mount *mnt = kmem_cache_zalloc(mnt_cache, GFP_KERNEL);
@ -229,6 +237,7 @@ static struct mount *alloc_vfsmnt(const char *name)
#ifdef CONFIG_FSNOTIFY
INIT_HLIST_HEAD(&mnt->mnt_fsnotify_marks);
#endif
init_fs_pin(&mnt->mnt_umount, drop_mountpoint);
}
return mnt;
@ -1289,7 +1298,6 @@ static HLIST_HEAD(unmounted); /* protected by namespace_sem */
static void namespace_unlock(void)
{
struct mount *mnt;
struct hlist_head head = unmounted;
if (likely(hlist_empty(&head))) {
@ -1299,23 +1307,11 @@ static void namespace_unlock(void)
head.first->pprev = &head.first;
INIT_HLIST_HEAD(&unmounted);
/* undo decrements we'd done in umount_tree() */
hlist_for_each_entry(mnt, &head, mnt_hash)
if (mnt->mnt_ex_mountpoint.mnt)
mntget(mnt->mnt_ex_mountpoint.mnt);
up_write(&namespace_sem);
synchronize_rcu();
while (!hlist_empty(&head)) {
mnt = hlist_entry(head.first, struct mount, mnt_hash);
hlist_del_init(&mnt->mnt_hash);
if (mnt->mnt_ex_mountpoint.mnt)
path_put(&mnt->mnt_ex_mountpoint);
mntput(&mnt->mnt);
}
group_pin_kill(&head);
}
static inline void namespace_lock(void)
@ -1334,7 +1330,6 @@ void umount_tree(struct mount *mnt, int how)
{
HLIST_HEAD(tmp_list);
struct mount *p;
struct mount *last = NULL;
for (p = mnt; p; p = next_mnt(p, mnt)) {
hlist_del_init_rcu(&p->mnt_hash);
@ -1347,33 +1342,28 @@ void umount_tree(struct mount *mnt, int how)
if (how)
propagate_umount(&tmp_list);
hlist_for_each_entry(p, &tmp_list, mnt_hash) {
while (!hlist_empty(&tmp_list)) {
p = hlist_entry(tmp_list.first, struct mount, mnt_hash);
hlist_del_init_rcu(&p->mnt_hash);
list_del_init(&p->mnt_expire);
list_del_init(&p->mnt_list);
__touch_mnt_namespace(p->mnt_ns);
p->mnt_ns = NULL;
if (how < 2)
p->mnt.mnt_flags |= MNT_SYNC_UMOUNT;
pin_insert_group(&p->mnt_umount, &p->mnt_parent->mnt, &unmounted);
if (mnt_has_parent(p)) {
hlist_del_init(&p->mnt_mp_list);
put_mountpoint(p->mnt_mp);
mnt_add_count(p->mnt_parent, -1);
/* move the reference to mountpoint into ->mnt_ex_mountpoint */
p->mnt_ex_mountpoint.dentry = p->mnt_mountpoint;
p->mnt_ex_mountpoint.mnt = &p->mnt_parent->mnt;
/* old mountpoint will be dropped when we can do that */
p->mnt_ex_mountpoint = p->mnt_mountpoint;
p->mnt_mountpoint = p->mnt.mnt_root;
p->mnt_parent = p;
p->mnt_mp = NULL;
}
change_mnt_propagation(p, MS_PRIVATE);
last = p;
}
if (last) {
last->mnt_hash.next = unmounted.first;
if (unmounted.first)
unmounted.first->pprev = &last->mnt_hash.next;
unmounted.first = tmp_list.first;
unmounted.first->pprev = &unmounted.first;
}
}