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Diffstat (limited to 'fs/namespace.c')
-rw-r--r--fs/namespace.c120
1 files changed, 64 insertions, 56 deletions
diff --git a/fs/namespace.c b/fs/namespace.c
index 14935a0500a2..1b466c54a357 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -787,15 +787,11 @@ int __legitimize_mnt(struct vfsmount *bastard, unsigned seq)
return 0;
mnt = real_mount(bastard);
mnt_add_count(mnt, 1);
- smp_mb(); // see mntput_no_expire()
+ smp_mb(); // see mntput_no_expire() and do_umount()
if (likely(!read_seqretry(&mount_lock, seq)))
return 0;
- if (bastard->mnt_flags & MNT_SYNC_UMOUNT) {
- mnt_add_count(mnt, -1);
- return 1;
- }
lock_mount_hash();
- if (unlikely(bastard->mnt_flags & MNT_DOOMED)) {
+ if (unlikely(bastard->mnt_flags & (MNT_SYNC_UMOUNT | MNT_DOOMED))) {
mnt_add_count(mnt, -1);
unlock_mount_hash();
return 1;
@@ -1830,6 +1826,8 @@ static inline void namespace_lock(void)
down_write(&namespace_sem);
}
+DEFINE_GUARD(namespace_lock, struct rw_semaphore *, namespace_lock(), namespace_unlock())
+
enum umount_tree_flags {
UMOUNT_SYNC = 1,
UMOUNT_PROPAGATE = 2,
@@ -2046,6 +2044,7 @@ static int do_umount(struct mount *mnt, int flags)
umount_tree(mnt, UMOUNT_PROPAGATE);
retval = 0;
} else {
+ smp_mb(); // paired with __legitimize_mnt()
shrink_submounts(mnt);
retval = -EBUSY;
if (!propagate_mount_busy(mnt, 2)) {
@@ -2383,7 +2382,7 @@ void dissolve_on_fput(struct vfsmount *mnt)
return;
}
- scoped_guard(rwsem_write, &namespace_sem) {
+ scoped_guard(namespace_lock, &namespace_sem) {
ns = m->mnt_ns;
if (!must_dissolve(ns))
return;
@@ -2824,56 +2823,62 @@ static struct mountpoint *do_lock_mount(struct path *path, bool beneath)
struct vfsmount *mnt = path->mnt;
struct dentry *dentry;
struct mountpoint *mp = ERR_PTR(-ENOENT);
+ struct path under = {};
for (;;) {
- struct mount *m;
+ struct mount *m = real_mount(mnt);
if (beneath) {
- m = real_mount(mnt);
+ path_put(&under);
read_seqlock_excl(&mount_lock);
- dentry = dget(m->mnt_mountpoint);
+ under.mnt = mntget(&m->mnt_parent->mnt);
+ under.dentry = dget(m->mnt_mountpoint);
read_sequnlock_excl(&mount_lock);
+ dentry = under.dentry;
} else {
dentry = path->dentry;
}
inode_lock(dentry->d_inode);
- if (unlikely(cant_mount(dentry))) {
- inode_unlock(dentry->d_inode);
- goto out;
- }
-
namespace_lock();
- if (beneath && (!is_mounted(mnt) || m->mnt_mountpoint != dentry)) {
+ if (unlikely(cant_mount(dentry) || !is_mounted(mnt)))
+ break; // not to be mounted on
+
+ if (beneath && unlikely(m->mnt_mountpoint != dentry ||
+ &m->mnt_parent->mnt != under.mnt)) {
namespace_unlock();
inode_unlock(dentry->d_inode);
- goto out;
+ continue; // got moved
}
mnt = lookup_mnt(path);
- if (likely(!mnt))
+ if (unlikely(mnt)) {
+ namespace_unlock();
+ inode_unlock(dentry->d_inode);
+ path_put(path);
+ path->mnt = mnt;
+ path->dentry = dget(mnt->mnt_root);
+ continue; // got overmounted
+ }
+ mp = get_mountpoint(dentry);
+ if (IS_ERR(mp))
break;
-
- namespace_unlock();
- inode_unlock(dentry->d_inode);
- if (beneath)
- dput(dentry);
- path_put(path);
- path->mnt = mnt;
- path->dentry = dget(mnt->mnt_root);
- }
-
- mp = get_mountpoint(dentry);
- if (IS_ERR(mp)) {
- namespace_unlock();
- inode_unlock(dentry->d_inode);
+ if (beneath) {
+ /*
+ * @under duplicates the references that will stay
+ * at least until namespace_unlock(), so the path_put()
+ * below is safe (and OK to do under namespace_lock -
+ * we are not dropping the final references here).
+ */
+ path_put(&under);
+ }
+ return mp;
}
-
-out:
+ namespace_unlock();
+ inode_unlock(dentry->d_inode);
if (beneath)
- dput(dentry);
-
+ path_put(&under);
return mp;
}
@@ -2884,14 +2889,11 @@ static inline struct mountpoint *lock_mount(struct path *path)
static void unlock_mount(struct mountpoint *where)
{
- struct dentry *dentry = where->m_dentry;
-
+ inode_unlock(where->m_dentry->d_inode);
read_seqlock_excl(&mount_lock);
put_mountpoint(where);
read_sequnlock_excl(&mount_lock);
-
namespace_unlock();
- inode_unlock(dentry->d_inode);
}
static int graft_tree(struct mount *mnt, struct mount *p, struct mountpoint *mp)
@@ -3555,7 +3557,8 @@ static int can_move_mount_beneath(const struct path *from,
* @mnt_from itself. This defeats the whole purpose of mounting
* @mnt_from beneath @mnt_to.
*/
- if (propagation_would_overmount(parent_mnt_to, mnt_from, mp))
+ if (check_mnt(mnt_from) &&
+ propagation_would_overmount(parent_mnt_to, mnt_from, mp))
return -EINVAL;
return 0;
@@ -3713,15 +3716,14 @@ static int do_move_mount(struct path *old_path,
if (err)
goto out;
- if (is_anon_ns(ns))
- ns->mntns_flags &= ~MNTNS_PROPAGATING;
-
/* if the mount is moved, it should no longer be expire
* automatically */
list_del_init(&old->mnt_expire);
if (attached)
put_mountpoint(old_mp);
out:
+ if (is_anon_ns(ns))
+ ns->mntns_flags &= ~MNTNS_PROPAGATING;
unlock_mount(mp);
if (!err) {
if (attached) {
@@ -5189,8 +5191,8 @@ static void finish_mount_kattr(struct mount_kattr *kattr)
mnt_idmap_put(kattr->mnt_idmap);
}
-static int copy_mount_setattr(struct mount_attr __user *uattr, size_t usize,
- struct mount_kattr *kattr)
+static int wants_mount_setattr(struct mount_attr __user *uattr, size_t usize,
+ struct mount_kattr *kattr)
{
int ret;
struct mount_attr attr;
@@ -5213,9 +5215,13 @@ static int copy_mount_setattr(struct mount_attr __user *uattr, size_t usize,
if (attr.attr_set == 0 &&
attr.attr_clr == 0 &&
attr.propagation == 0)
- return 0;
+ return 0; /* Tell caller to not bother. */
+
+ ret = build_mount_kattr(&attr, usize, kattr);
+ if (ret < 0)
+ return ret;
- return build_mount_kattr(&attr, usize, kattr);
+ return 1;
}
SYSCALL_DEFINE5(mount_setattr, int, dfd, const char __user *, path,
@@ -5247,8 +5253,8 @@ SYSCALL_DEFINE5(mount_setattr, int, dfd, const char __user *, path,
if (flags & AT_RECURSIVE)
kattr.kflags |= MOUNT_KATTR_RECURSE;
- err = copy_mount_setattr(uattr, usize, &kattr);
- if (err)
+ err = wants_mount_setattr(uattr, usize, &kattr);
+ if (err <= 0)
return err;
err = user_path_at(dfd, path, kattr.lookup_flags, &target);
@@ -5282,15 +5288,17 @@ SYSCALL_DEFINE5(open_tree_attr, int, dfd, const char __user *, filename,
if (flags & AT_RECURSIVE)
kattr.kflags |= MOUNT_KATTR_RECURSE;
- ret = copy_mount_setattr(uattr, usize, &kattr);
- if (ret)
+ ret = wants_mount_setattr(uattr, usize, &kattr);
+ if (ret < 0)
return ret;
- ret = do_mount_setattr(&file->f_path, &kattr);
- if (ret)
- return ret;
+ if (ret) {
+ ret = do_mount_setattr(&file->f_path, &kattr);
+ if (ret)
+ return ret;
- finish_mount_kattr(&kattr);
+ finish_mount_kattr(&kattr);
+ }
}
fd = get_unused_fd_flags(flags & O_CLOEXEC);
generated by cgit (git 2.34.1) at 2025-05-13 20:35:37 +0000