diff options
Diffstat (limited to 'fs/namespace.c')
| -rw-r--r-- | fs/namespace.c | 93 |
1 files changed, 90 insertions, 3 deletions
diff --git a/fs/namespace.c b/fs/namespace.c index 8ca6317cb401..cefa1d9939b0 100644 --- a/fs/namespace.c +++ b/fs/namespace.c @@ -41,6 +41,7 @@ __cacheline_aligned_in_smp DEFINE_SPINLOCK(vfsmount_lock); static int event; static DEFINE_IDA(mnt_id_ida); +static DEFINE_IDA(mnt_group_ida); static struct list_head *mount_hashtable __read_mostly; static struct kmem_cache *mnt_cache __read_mostly; @@ -83,6 +84,28 @@ static void mnt_free_id(struct vfsmount *mnt) spin_unlock(&vfsmount_lock); } +/* + * Allocate a new peer group ID + * + * mnt_group_ida is protected by namespace_sem + */ +static int mnt_alloc_group_id(struct vfsmount *mnt) +{ + if (!ida_pre_get(&mnt_group_ida, GFP_KERNEL)) + return -ENOMEM; + + return ida_get_new_above(&mnt_group_ida, 1, &mnt->mnt_group_id); +} + +/* + * Release a peer group ID + */ +void mnt_release_group_id(struct vfsmount *mnt) +{ + ida_remove(&mnt_group_ida, mnt->mnt_group_id); + mnt->mnt_group_id = 0; +} + struct vfsmount *alloc_vfsmnt(const char *name) { struct vfsmount *mnt = kmem_cache_zalloc(mnt_cache, GFP_KERNEL); @@ -533,6 +556,17 @@ static struct vfsmount *clone_mnt(struct vfsmount *old, struct dentry *root, struct vfsmount *mnt = alloc_vfsmnt(old->mnt_devname); if (mnt) { + if (flag & (CL_SLAVE | CL_PRIVATE)) + mnt->mnt_group_id = 0; /* not a peer of original */ + else + mnt->mnt_group_id = old->mnt_group_id; + + if ((flag & CL_MAKE_SHARED) && !mnt->mnt_group_id) { + int err = mnt_alloc_group_id(mnt); + if (err) + goto out_free; + } + mnt->mnt_flags = old->mnt_flags; atomic_inc(&sb->s_active); mnt->mnt_sb = sb; @@ -562,6 +596,10 @@ static struct vfsmount *clone_mnt(struct vfsmount *old, struct dentry *root, } } return mnt; + + out_free: + free_vfsmnt(mnt); + return NULL; } static inline void __mntput(struct vfsmount *mnt) @@ -1142,6 +1180,33 @@ void drop_collected_mounts(struct vfsmount *mnt) release_mounts(&umount_list); } +static void cleanup_group_ids(struct vfsmount *mnt, struct vfsmount *end) +{ + struct vfsmount *p; + + for (p = mnt; p != end; p = next_mnt(p, mnt)) { + if (p->mnt_group_id && !IS_MNT_SHARED(p)) + mnt_release_group_id(p); + } +} + +static int invent_group_ids(struct vfsmount *mnt, bool recurse) +{ + struct vfsmount *p; + + for (p = mnt; p; p = recurse ? next_mnt(p, mnt) : NULL) { + if (!p->mnt_group_id && !IS_MNT_SHARED(p)) { + int err = mnt_alloc_group_id(p); + if (err) { + cleanup_group_ids(mnt, p); + return err; + } + } + } + + return 0; +} + /* * @source_mnt : mount tree to be attached * @nd : place the mount tree @source_mnt is attached @@ -1212,9 +1277,16 @@ static int attach_recursive_mnt(struct vfsmount *source_mnt, struct vfsmount *dest_mnt = path->mnt; struct dentry *dest_dentry = path->dentry; struct vfsmount *child, *p; + int err; - if (propagate_mnt(dest_mnt, dest_dentry, source_mnt, &tree_list)) - return -EINVAL; + if (IS_MNT_SHARED(dest_mnt)) { + err = invent_group_ids(source_mnt, true); + if (err) + goto out; + } + err = propagate_mnt(dest_mnt, dest_dentry, source_mnt, &tree_list); + if (err) + goto out_cleanup_ids; if (IS_MNT_SHARED(dest_mnt)) { for (p = source_mnt; p; p = next_mnt(p, source_mnt)) @@ -1237,6 +1309,12 @@ static int attach_recursive_mnt(struct vfsmount *source_mnt, } spin_unlock(&vfsmount_lock); return 0; + + out_cleanup_ids: + if (IS_MNT_SHARED(dest_mnt)) + cleanup_group_ids(source_mnt, NULL); + out: + return err; } static int graft_tree(struct vfsmount *mnt, struct path *path) @@ -1277,6 +1355,7 @@ static noinline int do_change_type(struct nameidata *nd, int flag) struct vfsmount *m, *mnt = nd->path.mnt; int recurse = flag & MS_REC; int type = flag & ~MS_REC; + int err = 0; if (!capable(CAP_SYS_ADMIN)) return -EPERM; @@ -1285,12 +1364,20 @@ static noinline int do_change_type(struct nameidata *nd, int flag) return -EINVAL; down_write(&namespace_sem); + if (type == MS_SHARED) { + err = invent_group_ids(mnt, recurse); + if (err) + goto out_unlock; + } + spin_lock(&vfsmount_lock); for (m = mnt; m; m = (recurse ? next_mnt(m, mnt) : NULL)) change_mnt_propagation(m, type); spin_unlock(&vfsmount_lock); + + out_unlock: up_write(&namespace_sem); - return 0; + return err; } /* |