X-Git-Url: http://plrg.eecs.uci.edu/git/?a=blobdiff_plain;f=fs%2Fnamespace.c;h=c1477882a8537094ea5ee2b5470b3be0d68c2994;hb=968ccb6e8330739448c9fb40a6ed08013b17cbc7;hp=0570729c87fd22dd299c50ee0303f43c384e4932;hpb=e4b35f952be9f5706b22e38c1925b7ac49080d72;p=firefly-linux-kernel-4.4.55.git diff --git a/fs/namespace.c b/fs/namespace.c index 0570729c87fd..c1477882a853 100644 --- a/fs/namespace.c +++ b/fs/namespace.c @@ -577,6 +577,7 @@ int sb_prepare_remount_readonly(struct super_block *sb) static void free_vfsmnt(struct mount *mnt) { + kfree(mnt->mnt.data); kfree_const(mnt->mnt_devname); #ifdef CONFIG_SMP free_percpu(mnt->mnt_pcp); @@ -637,28 +638,6 @@ struct mount *__lookup_mnt(struct vfsmount *mnt, struct dentry *dentry) return NULL; } -/* - * find the last mount at @dentry on vfsmount @mnt. - * mount_lock must be held. - */ -struct mount *__lookup_mnt_last(struct vfsmount *mnt, struct dentry *dentry) -{ - struct mount *p, *res = NULL; - p = __lookup_mnt(mnt, dentry); - if (!p) - goto out; - if (!(p->mnt.mnt_flags & MNT_UMOUNT)) - res = p; - hlist_for_each_entry_continue(p, mnt_hash) { - if (&p->mnt_parent->mnt != mnt || p->mnt_mountpoint != dentry) - break; - if (!(p->mnt.mnt_flags & MNT_UMOUNT)) - res = p; - } -out: - return res; -} - /* * lookup_mnt - Return the first child mount mounted at path * @@ -743,26 +722,50 @@ static struct mountpoint *lookup_mountpoint(struct dentry *dentry) return NULL; } -static struct mountpoint *new_mountpoint(struct dentry *dentry) +static struct mountpoint *get_mountpoint(struct dentry *dentry) { - struct hlist_head *chain = mp_hash(dentry); - struct mountpoint *mp; + struct mountpoint *mp, *new = NULL; int ret; - mp = kmalloc(sizeof(struct mountpoint), GFP_KERNEL); - if (!mp) + if (d_mountpoint(dentry)) { +mountpoint: + read_seqlock_excl(&mount_lock); + mp = lookup_mountpoint(dentry); + read_sequnlock_excl(&mount_lock); + if (mp) + goto done; + } + + if (!new) + new = kmalloc(sizeof(struct mountpoint), GFP_KERNEL); + if (!new) return ERR_PTR(-ENOMEM); + + /* Exactly one processes may set d_mounted */ ret = d_set_mounted(dentry); - if (ret) { - kfree(mp); - return ERR_PTR(ret); - } - mp->m_dentry = dentry; - mp->m_count = 1; - hlist_add_head(&mp->m_hash, chain); - INIT_HLIST_HEAD(&mp->m_list); + /* Someone else set d_mounted? */ + if (ret == -EBUSY) + goto mountpoint; + + /* The dentry is not available as a mountpoint? */ + mp = ERR_PTR(ret); + if (ret) + goto done; + + /* Add the new mountpoint to the hash table */ + read_seqlock_excl(&mount_lock); + new->m_dentry = dentry; + new->m_count = 1; + hlist_add_head(&new->m_hash, mp_hash(dentry)); + INIT_HLIST_HEAD(&new->m_list); + read_sequnlock_excl(&mount_lock); + + mp = new; + new = NULL; +done: + kfree(new); return mp; } @@ -855,6 +858,13 @@ void mnt_set_mountpoint(struct mount *mnt, hlist_add_head(&child_mnt->mnt_mp_list, &mp->m_list); } +static void __attach_mnt(struct mount *mnt, struct mount *parent) +{ + hlist_add_head_rcu(&mnt->mnt_hash, + m_hash(&parent->mnt, mnt->mnt_mountpoint)); + list_add_tail(&mnt->mnt_child, &parent->mnt_mounts); +} + /* * vfsmount lock must be held for write */ @@ -863,28 +873,45 @@ static void attach_mnt(struct mount *mnt, struct mountpoint *mp) { mnt_set_mountpoint(parent, mp, mnt); - hlist_add_head_rcu(&mnt->mnt_hash, m_hash(&parent->mnt, mp->m_dentry)); - list_add_tail(&mnt->mnt_child, &parent->mnt_mounts); + __attach_mnt(mnt, parent); } -static void attach_shadowed(struct mount *mnt, - struct mount *parent, - struct mount *shadows) +void mnt_change_mountpoint(struct mount *parent, struct mountpoint *mp, struct mount *mnt) { - if (shadows) { - hlist_add_behind_rcu(&mnt->mnt_hash, &shadows->mnt_hash); - list_add(&mnt->mnt_child, &shadows->mnt_child); - } else { - hlist_add_head_rcu(&mnt->mnt_hash, - m_hash(&parent->mnt, mnt->mnt_mountpoint)); - list_add_tail(&mnt->mnt_child, &parent->mnt_mounts); - } + struct mountpoint *old_mp = mnt->mnt_mp; + struct dentry *old_mountpoint = mnt->mnt_mountpoint; + struct mount *old_parent = mnt->mnt_parent; + + list_del_init(&mnt->mnt_child); + hlist_del_init(&mnt->mnt_mp_list); + hlist_del_init_rcu(&mnt->mnt_hash); + + attach_mnt(mnt, parent, mp); + + put_mountpoint(old_mp); + + /* + * Safely avoid even the suggestion this code might sleep or + * lock the mount hash by taking advantage of the knowledge that + * mnt_change_mountpoint will not release the final reference + * to a mountpoint. + * + * During mounting, the mount passed in as the parent mount will + * continue to use the old mountpoint and during unmounting, the + * old mountpoint will continue to exist until namespace_unlock, + * which happens well after mnt_change_mountpoint. + */ + spin_lock(&old_mountpoint->d_lock); + old_mountpoint->d_lockref.count--; + spin_unlock(&old_mountpoint->d_lock); + + mnt_add_count(old_parent, -1); } /* * vfsmount lock must be held for write */ -static void commit_tree(struct mount *mnt, struct mount *shadows) +static void commit_tree(struct mount *mnt) { struct mount *parent = mnt->mnt_parent; struct mount *m; @@ -899,7 +926,7 @@ static void commit_tree(struct mount *mnt, struct mount *shadows) list_splice(&head, n->list.prev); - attach_shadowed(mnt, parent, shadows); + __attach_mnt(mnt, parent); touch_mnt_namespace(n); } @@ -942,11 +969,21 @@ vfs_kern_mount(struct file_system_type *type, int flags, const char *name, void if (!mnt) return ERR_PTR(-ENOMEM); + mnt->mnt.data = NULL; + if (type->alloc_mnt_data) { + mnt->mnt.data = type->alloc_mnt_data(); + if (!mnt->mnt.data) { + mnt_free_id(mnt); + free_vfsmnt(mnt); + return ERR_PTR(-ENOMEM); + } + } if (flags & MS_KERNMOUNT) mnt->mnt.mnt_flags = MNT_INTERNAL; - root = mount_fs(type, flags, name, data); + root = mount_fs(type, flags, name, &mnt->mnt, data); if (IS_ERR(root)) { + kfree(mnt->mnt.data); mnt_free_id(mnt); free_vfsmnt(mnt); return ERR_CAST(root); @@ -974,6 +1011,14 @@ static struct mount *clone_mnt(struct mount *old, struct dentry *root, if (!mnt) return ERR_PTR(-ENOMEM); + if (sb->s_op->clone_mnt_data) { + mnt->mnt.data = sb->s_op->clone_mnt_data(old->mnt.data); + if (!mnt->mnt.data) { + err = -ENOMEM; + goto out_free; + } + } + if (flag & (CL_SLAVE | CL_PRIVATE | CL_SHARED_TO_SLAVE)) mnt->mnt_group_id = 0; /* not a peer of original */ else @@ -1042,6 +1087,7 @@ static struct mount *clone_mnt(struct mount *old, struct dentry *root, return mnt; out_free: + kfree(mnt->mnt.data); mnt_free_id(mnt); free_vfsmnt(mnt); return ERR_PTR(err); @@ -1557,11 +1603,12 @@ void __detach_mounts(struct dentry *dentry) struct mount *mnt; namespace_lock(); + lock_mount_hash(); mp = lookup_mountpoint(dentry); if (IS_ERR_OR_NULL(mp)) goto out_unlock; - lock_mount_hash(); + event++; while (!hlist_empty(&mp->m_list)) { mnt = hlist_entry(mp->m_list.first, struct mount, mnt_mp_list); if (mnt->mnt.mnt_flags & MNT_UMOUNT) { @@ -1570,9 +1617,9 @@ void __detach_mounts(struct dentry *dentry) } else umount_tree(mnt, UMOUNT_CONNECTED); } - unlock_mount_hash(); put_mountpoint(mp); out_unlock: + unlock_mount_hash(); namespace_unlock(); } @@ -1693,7 +1740,6 @@ struct mount *copy_tree(struct mount *mnt, struct dentry *dentry, continue; for (s = r; s; s = next_mnt(s, r)) { - struct mount *t = NULL; if (!(flag & CL_COPY_UNBINDABLE) && IS_MNT_UNBINDABLE(s)) { s = skip_mnt_tree(s); @@ -1715,14 +1761,7 @@ struct mount *copy_tree(struct mount *mnt, struct dentry *dentry, goto out; lock_mount_hash(); list_add_tail(&q->mnt_list, &res->mnt_list); - mnt_set_mountpoint(parent, p->mnt_mp, q); - if (!list_empty(&parent->mnt_mounts)) { - t = list_last_entry(&parent->mnt_mounts, - struct mount, mnt_child); - if (t->mnt_mp != p->mnt_mp) - t = NULL; - } - attach_shadowed(q, parent, t); + attach_mnt(q, parent, p->mnt_mp); unlock_mount_hash(); } } @@ -1900,10 +1939,18 @@ static int attach_recursive_mnt(struct mount *source_mnt, struct path *parent_path) { HLIST_HEAD(tree_list); + struct mountpoint *smp; struct mount *child, *p; struct hlist_node *n; int err; + /* Preallocate a mountpoint in case the new mounts need + * to be tucked under other mounts. + */ + smp = get_mountpoint(source_mnt->mnt.mnt_root); + if (IS_ERR(smp)) + return PTR_ERR(smp); + if (IS_MNT_SHARED(dest_mnt)) { err = invent_group_ids(source_mnt, true); if (err) @@ -1923,16 +1970,19 @@ static int attach_recursive_mnt(struct mount *source_mnt, touch_mnt_namespace(source_mnt->mnt_ns); } else { mnt_set_mountpoint(dest_mnt, dest_mp, source_mnt); - commit_tree(source_mnt, NULL); + commit_tree(source_mnt); } hlist_for_each_entry_safe(child, n, &tree_list, mnt_hash) { struct mount *q; hlist_del_init(&child->mnt_hash); - q = __lookup_mnt_last(&child->mnt_parent->mnt, - child->mnt_mountpoint); - commit_tree(child, q); + q = __lookup_mnt(&child->mnt_parent->mnt, + child->mnt_mountpoint); + if (q) + mnt_change_mountpoint(child, smp, q); + commit_tree(child); } + put_mountpoint(smp); unlock_mount_hash(); return 0; @@ -1945,6 +1995,10 @@ static int attach_recursive_mnt(struct mount *source_mnt, unlock_mount_hash(); cleanup_group_ids(source_mnt, NULL); out: + read_seqlock_excl(&mount_lock); + put_mountpoint(smp); + read_sequnlock_excl(&mount_lock); + return err; } @@ -1961,9 +2015,7 @@ retry: namespace_lock(); mnt = lookup_mnt(path); if (likely(!mnt)) { - struct mountpoint *mp = lookup_mountpoint(dentry); - if (!mp) - mp = new_mountpoint(dentry); + struct mountpoint *mp = get_mountpoint(dentry); if (IS_ERR(mp)) { namespace_unlock(); mutex_unlock(&dentry->d_inode->i_mutex); @@ -1982,7 +2034,11 @@ retry: static void unlock_mount(struct mountpoint *where) { struct dentry *dentry = where->m_dentry; + + read_seqlock_excl(&mount_lock); put_mountpoint(where); + read_sequnlock_excl(&mount_lock); + namespace_unlock(); mutex_unlock(&dentry->d_inode->i_mutex); } @@ -2207,8 +2263,14 @@ static int do_remount(struct path *path, int flags, int mnt_flags, err = change_mount_flags(path->mnt, flags); else if (!capable(CAP_SYS_ADMIN)) err = -EPERM; - else - err = do_remount_sb(sb, flags, data, 0); + else { + err = do_remount_sb2(path->mnt, sb, flags, data, 0); + namespace_lock(); + lock_mount_hash(); + propagate_remount(mnt); + unlock_mount_hash(); + namespace_unlock(); + } if (!err) { lock_mount_hash(); mnt_flags |= mnt->mnt.mnt_flags & ~MNT_USER_SETTABLE_MASK; @@ -2401,8 +2463,10 @@ static int do_new_mount(struct path *path, const char *fstype, int flags, mnt_flags |= MNT_NODEV | MNT_LOCK_NODEV; } if (type->fs_flags & FS_USERNS_VISIBLE) { - if (!fs_fully_visible(type, &mnt_flags)) + if (!fs_fully_visible(type, &mnt_flags)) { + put_filesystem(type); return -EPERM; + } } } @@ -3052,9 +3116,9 @@ SYSCALL_DEFINE2(pivot_root, const char __user *, new_root, touch_mnt_namespace(current->nsproxy->mnt_ns); /* A moved mount should not expire automatically */ list_del_init(&new_mnt->mnt_expire); + put_mountpoint(root_mp); unlock_mount_hash(); chroot_fs_refs(&root, &new); - put_mountpoint(root_mp); error = 0; out4: unlock_mount(old_mp); @@ -3236,6 +3300,10 @@ static bool fs_fully_visible(struct file_system_type *type, int *new_mnt_flags) if (mnt->mnt.mnt_sb->s_iflags & SB_I_NOEXEC) mnt_flags &= ~(MNT_LOCK_NOSUID | MNT_LOCK_NOEXEC); + /* Don't miss readonly hidden in the superblock flags */ + if (mnt->mnt.mnt_sb->s_flags & MS_RDONLY) + mnt_flags |= MNT_LOCK_READONLY; + /* Verify the mount flags are equal to or more permissive * than the proposed new mount. */ @@ -3262,7 +3330,7 @@ static bool fs_fully_visible(struct file_system_type *type, int *new_mnt_flags) list_for_each_entry(child, &mnt->mnt_mounts, mnt_child) { struct inode *inode = child->mnt_mountpoint->d_inode; /* Only worry about locked mounts */ - if (!(mnt_flags & MNT_LOCKED)) + if (!(child->mnt.mnt_flags & MNT_LOCKED)) continue; /* Is the directory permanetly empty? */ if (!is_empty_dir_inode(inode))