diff options
author | Linus Torvalds <torvalds@linux-foundation.org> | 2008-03-28 15:23:01 -0700 |
---|---|---|
committer | Linus Torvalds <torvalds@linux-foundation.org> | 2008-03-28 15:23:01 -0700 |
commit | af8be4e4b316df36a00c1e52a9970c253783b57e (patch) | |
tree | 6d56665916e601ed6a933d6f85c22ee8512c6531 /fs/namespace.c | |
parent | d478376cb0dc9ab16a2b6e02fd8cd1174e724c64 (diff) | |
parent | 6758f953d05378d907a164c67934cd86183d9c88 (diff) |
Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs-2.6
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs-2.6:
[PATCH] mnt_expire is protected by namespace_sem, no need for vfsmount_lock
[PATCH] do shrink_submounts() for all fs types
[PATCH] sanitize locking in mark_mounts_for_expiry() and shrink_submounts()
[PATCH] count ghost references to vfsmounts
[PATCH] reduce stack footprint in namespace.c
Diffstat (limited to 'fs/namespace.c')
-rw-r--r-- | fs/namespace.c | 200 |
1 files changed, 69 insertions, 131 deletions
diff --git a/fs/namespace.c b/fs/namespace.c index 7953c96a207..94f026ec990 100644 --- a/fs/namespace.c +++ b/fs/namespace.c @@ -155,15 +155,15 @@ static void __touch_mnt_namespace(struct mnt_namespace *ns) } } -static void detach_mnt(struct vfsmount *mnt, struct nameidata *old_nd) +static void detach_mnt(struct vfsmount *mnt, struct path *old_path) { - old_nd->path.dentry = mnt->mnt_mountpoint; - old_nd->path.mnt = mnt->mnt_parent; + old_path->dentry = mnt->mnt_mountpoint; + old_path->mnt = mnt->mnt_parent; mnt->mnt_parent = mnt; mnt->mnt_mountpoint = mnt->mnt_root; list_del_init(&mnt->mnt_child); list_del_init(&mnt->mnt_hash); - old_nd->path.dentry->d_mounted--; + old_path->dentry->d_mounted--; } void mnt_set_mountpoint(struct vfsmount *mnt, struct dentry *dentry, @@ -174,12 +174,12 @@ void mnt_set_mountpoint(struct vfsmount *mnt, struct dentry *dentry, dentry->d_mounted++; } -static void attach_mnt(struct vfsmount *mnt, struct nameidata *nd) +static void attach_mnt(struct vfsmount *mnt, struct path *path) { - mnt_set_mountpoint(nd->path.mnt, nd->path.dentry, mnt); + mnt_set_mountpoint(path->mnt, path->dentry, mnt); list_add_tail(&mnt->mnt_hash, mount_hashtable + - hash(nd->path.mnt, nd->path.dentry)); - list_add_tail(&mnt->mnt_child, &nd->path.mnt->mnt_mounts); + hash(path->mnt, path->dentry)); + list_add_tail(&mnt->mnt_child, &path->mnt->mnt_mounts); } /* @@ -262,10 +262,8 @@ static struct vfsmount *clone_mnt(struct vfsmount *old, struct dentry *root, /* stick the duplicate mount on the same expiry list * as the original if that was on one */ if (flag & CL_EXPIRE) { - spin_lock(&vfsmount_lock); if (!list_empty(&old->mnt_expire)) list_add(&mnt->mnt_expire, &old->mnt_expire); - spin_unlock(&vfsmount_lock); } } return mnt; @@ -548,6 +546,7 @@ void release_mounts(struct list_head *head) m = mnt->mnt_parent; mnt->mnt_mountpoint = mnt->mnt_root; mnt->mnt_parent = mnt; + m->mnt_ghosts--; spin_unlock(&vfsmount_lock); dput(dentry); mntput(m); @@ -572,12 +571,16 @@ void umount_tree(struct vfsmount *mnt, int propagate, struct list_head *kill) __touch_mnt_namespace(p->mnt_ns); p->mnt_ns = NULL; list_del_init(&p->mnt_child); - if (p->mnt_parent != p) + if (p->mnt_parent != p) { + p->mnt_parent->mnt_ghosts++; p->mnt_mountpoint->d_mounted--; + } change_mnt_propagation(p, MS_PRIVATE); } } +static void shrink_submounts(struct vfsmount *mnt, struct list_head *umounts); + static int do_umount(struct vfsmount *mnt, int flags) { struct super_block *sb = mnt->mnt_sb; @@ -650,6 +653,9 @@ static int do_umount(struct vfsmount *mnt, int flags) spin_lock(&vfsmount_lock); event++; + if (!(flags & MNT_DETACH)) + shrink_submounts(mnt, &umount_list); + retval = -EBUSY; if (flags & MNT_DETACH || !propagate_mount_busy(mnt, 2)) { if (!list_empty(&mnt->mnt_list)) @@ -744,7 +750,7 @@ struct vfsmount *copy_tree(struct vfsmount *mnt, struct dentry *dentry, int flag) { struct vfsmount *res, *p, *q, *r, *s; - struct nameidata nd; + struct path path; if (!(flag & CL_COPY_ALL) && IS_MNT_UNBINDABLE(mnt)) return NULL; @@ -769,14 +775,14 @@ struct vfsmount *copy_tree(struct vfsmount *mnt, struct dentry *dentry, q = q->mnt_parent; } p = s; - nd.path.mnt = q; - nd.path.dentry = p->mnt_mountpoint; + path.mnt = q; + path.dentry = p->mnt_mountpoint; q = clone_mnt(p, p->mnt_root, flag); if (!q) goto Enomem; spin_lock(&vfsmount_lock); list_add_tail(&q->mnt_list, &res->mnt_list); - attach_mnt(q, &nd); + attach_mnt(q, &path); spin_unlock(&vfsmount_lock); } } @@ -876,11 +882,11 @@ void drop_collected_mounts(struct vfsmount *mnt) * in allocations. */ static int attach_recursive_mnt(struct vfsmount *source_mnt, - struct nameidata *nd, struct nameidata *parent_nd) + struct path *path, struct path *parent_path) { LIST_HEAD(tree_list); - struct vfsmount *dest_mnt = nd->path.mnt; - struct dentry *dest_dentry = nd->path.dentry; + struct vfsmount *dest_mnt = path->mnt; + struct dentry *dest_dentry = path->dentry; struct vfsmount *child, *p; if (propagate_mnt(dest_mnt, dest_dentry, source_mnt, &tree_list)) @@ -892,9 +898,9 @@ static int attach_recursive_mnt(struct vfsmount *source_mnt, } spin_lock(&vfsmount_lock); - if (parent_nd) { - detach_mnt(source_mnt, parent_nd); - attach_mnt(source_mnt, nd); + if (parent_path) { + detach_mnt(source_mnt, parent_path); + attach_mnt(source_mnt, path); touch_mnt_namespace(current->nsproxy->mnt_ns); } else { mnt_set_mountpoint(dest_mnt, dest_dentry, source_mnt); @@ -930,7 +936,7 @@ static int graft_tree(struct vfsmount *mnt, struct nameidata *nd) err = -ENOENT; if (IS_ROOT(nd->path.dentry) || !d_unhashed(nd->path.dentry)) - err = attach_recursive_mnt(mnt, nd, NULL); + err = attach_recursive_mnt(mnt, &nd->path, NULL); out_unlock: mutex_unlock(&nd->path.dentry->d_inode->i_mutex); if (!err) @@ -1059,7 +1065,8 @@ static inline int tree_contains_unbindable(struct vfsmount *mnt) */ static noinline int do_move_mount(struct nameidata *nd, char *old_name) { - struct nameidata old_nd, parent_nd; + struct nameidata old_nd; + struct path parent_path; struct vfsmount *p; int err = 0; if (!capable(CAP_SYS_ADMIN)) @@ -1114,21 +1121,19 @@ static noinline int do_move_mount(struct nameidata *nd, char *old_name) if (p == old_nd.path.mnt) goto out1; - err = attach_recursive_mnt(old_nd.path.mnt, nd, &parent_nd); + err = attach_recursive_mnt(old_nd.path.mnt, &nd->path, &parent_path); if (err) goto out1; - spin_lock(&vfsmount_lock); /* if the mount is moved, it should no longer be expire * automatically */ list_del_init(&old_nd.path.mnt->mnt_expire); - spin_unlock(&vfsmount_lock); out1: mutex_unlock(&nd->path.dentry->d_inode->i_mutex); out: up_write(&namespace_sem); if (!err) - path_put(&parent_nd.path); + path_put(&parent_path); path_put(&old_nd.path); return err; } @@ -1189,12 +1194,9 @@ int do_add_mount(struct vfsmount *newmnt, struct nameidata *nd, if ((err = graft_tree(newmnt, nd))) goto unlock; - if (fslist) { - /* add to the specified expiration list */ - spin_lock(&vfsmount_lock); + if (fslist) /* add to the specified expiration list */ list_add_tail(&newmnt->mnt_expire, fslist); - spin_unlock(&vfsmount_lock); - } + up_write(&namespace_sem); return 0; @@ -1206,75 +1208,6 @@ unlock: EXPORT_SYMBOL_GPL(do_add_mount); -static void expire_mount(struct vfsmount *mnt, struct list_head *mounts, - struct list_head *umounts) -{ - spin_lock(&vfsmount_lock); - - /* - * Check if mount is still attached, if not, let whoever holds it deal - * with the sucker - */ - if (mnt->mnt_parent == mnt) { - spin_unlock(&vfsmount_lock); - return; - } - - /* - * Check that it is still dead: the count should now be 2 - as - * contributed by the vfsmount parent and the mntget above - */ - if (!propagate_mount_busy(mnt, 2)) { - /* delete from the namespace */ - touch_mnt_namespace(mnt->mnt_ns); - list_del_init(&mnt->mnt_list); - mnt->mnt_ns = NULL; - umount_tree(mnt, 1, umounts); - spin_unlock(&vfsmount_lock); - } else { - /* - * Someone brought it back to life whilst we didn't have any - * locks held so return it to the expiration list - */ - list_add_tail(&mnt->mnt_expire, mounts); - spin_unlock(&vfsmount_lock); - } -} - -/* - * go through the vfsmounts we've just consigned to the graveyard to - * - check that they're still dead - * - delete the vfsmount from the appropriate namespace under lock - * - dispose of the corpse - */ -static void expire_mount_list(struct list_head *graveyard, struct list_head *mounts) -{ - struct mnt_namespace *ns; - struct vfsmount *mnt; - - while (!list_empty(graveyard)) { - LIST_HEAD(umounts); - mnt = list_first_entry(graveyard, struct vfsmount, mnt_expire); - list_del_init(&mnt->mnt_expire); - - /* don't do anything if the namespace is dead - all the - * vfsmounts from it are going away anyway */ - ns = mnt->mnt_ns; - if (!ns || !ns->root) - continue; - get_mnt_ns(ns); - - spin_unlock(&vfsmount_lock); - down_write(&namespace_sem); - expire_mount(mnt, mounts, &umounts); - up_write(&namespace_sem); - release_mounts(&umounts); - mntput(mnt); - put_mnt_ns(ns); - spin_lock(&vfsmount_lock); - } -} - /* * process a list of expirable mountpoints with the intent of discarding any * mountpoints that aren't in use and haven't been touched since last we came @@ -1284,10 +1217,12 @@ void mark_mounts_for_expiry(struct list_head *mounts) { struct vfsmount *mnt, *next; LIST_HEAD(graveyard); + LIST_HEAD(umounts); if (list_empty(mounts)) return; + down_write(&namespace_sem); spin_lock(&vfsmount_lock); /* extract from the expiration list every vfsmount that matches the @@ -1298,16 +1233,19 @@ void mark_mounts_for_expiry(struct list_head *mounts) */ list_for_each_entry_safe(mnt, next, mounts, mnt_expire) { if (!xchg(&mnt->mnt_expiry_mark, 1) || - atomic_read(&mnt->mnt_count) != 1) + propagate_mount_busy(mnt, 1)) continue; - - mntget(mnt); list_move(&mnt->mnt_expire, &graveyard); } - - expire_mount_list(&graveyard, mounts); - + while (!list_empty(&graveyard)) { + mnt = list_first_entry(&graveyard, struct vfsmount, mnt_expire); + touch_mnt_namespace(mnt->mnt_ns); + umount_tree(mnt, 1, &umounts); + } spin_unlock(&vfsmount_lock); + up_write(&namespace_sem); + + release_mounts(&umounts); } EXPORT_SYMBOL_GPL(mark_mounts_for_expiry); @@ -1343,7 +1281,6 @@ resume: } if (!propagate_mount_busy(mnt, 1)) { - mntget(mnt); list_move_tail(&mnt->mnt_expire, graveyard); found++; } @@ -1363,22 +1300,22 @@ resume: * process a list of expirable mountpoints with the intent of discarding any * submounts of a specific parent mountpoint */ -void shrink_submounts(struct vfsmount *mountpoint, struct list_head *mounts) +static void shrink_submounts(struct vfsmount *mnt, struct list_head *umounts) { LIST_HEAD(graveyard); - int found; - - spin_lock(&vfsmount_lock); + struct vfsmount *m; /* extract submounts of 'mountpoint' from the expiration list */ - while ((found = select_submounts(mountpoint, &graveyard)) != 0) - expire_mount_list(&graveyard, mounts); - - spin_unlock(&vfsmount_lock); + while (select_submounts(mnt, &graveyard)) { + while (!list_empty(&graveyard)) { + m = list_first_entry(&graveyard, struct vfsmount, + mnt_expire); + touch_mnt_namespace(mnt->mnt_ns); + umount_tree(mnt, 1, umounts); + } + } } -EXPORT_SYMBOL_GPL(shrink_submounts); - /* * Some copy_from_user() implementations do not return the exact number of * bytes remaining to copy on a fault. But copy_mount_options() requires that. @@ -1683,7 +1620,7 @@ void set_fs_pwd(struct fs_struct *fs, struct path *path) path_put(&old_pwd); } -static void chroot_fs_refs(struct nameidata *old_nd, struct nameidata *new_nd) +static void chroot_fs_refs(struct path *old_root, struct path *new_root) { struct task_struct *g, *p; struct fs_struct *fs; @@ -1695,12 +1632,12 @@ static void chroot_fs_refs(struct nameidata *old_nd, struct nameidata *new_nd) if (fs) { atomic_inc(&fs->count); task_unlock(p); - if (fs->root.dentry == old_nd->path.dentry - && fs->root.mnt == old_nd->path.mnt) - set_fs_root(fs, &new_nd->path); - if (fs->pwd.dentry == old_nd->path.dentry - && fs->pwd.mnt == old_nd->path.mnt) - set_fs_pwd(fs, &new_nd->path); + if (fs->root.dentry == old_root->dentry + && fs->root.mnt == old_root->mnt) + set_fs_root(fs, new_root); + if (fs->pwd.dentry == old_root->dentry + && fs->pwd.mnt == old_root->mnt) + set_fs_pwd(fs, new_root); put_fs_struct(fs); } else task_unlock(p); @@ -1737,7 +1674,8 @@ asmlinkage long sys_pivot_root(const char __user * new_root, const char __user * put_old) { struct vfsmount *tmp; - struct nameidata new_nd, old_nd, parent_nd, root_parent, user_nd; + struct nameidata new_nd, old_nd, user_nd; + struct path parent_path, root_parent; int error; if (!capable(CAP_SYS_ADMIN)) @@ -1811,19 +1749,19 @@ asmlinkage long sys_pivot_root(const char __user * new_root, goto out3; } else if (!is_subdir(old_nd.path.dentry, new_nd.path.dentry)) goto out3; - detach_mnt(new_nd.path.mnt, &parent_nd); + detach_mnt(new_nd.path.mnt, &parent_path); detach_mnt(user_nd.path.mnt, &root_parent); /* mount old root on put_old */ - attach_mnt(user_nd.path.mnt, &old_nd); + attach_mnt(user_nd.path.mnt, &old_nd.path); /* mount new_root on / */ attach_mnt(new_nd.path.mnt, &root_parent); touch_mnt_namespace(current->nsproxy->mnt_ns); spin_unlock(&vfsmount_lock); - chroot_fs_refs(&user_nd, &new_nd); + chroot_fs_refs(&user_nd.path, &new_nd.path); security_sb_post_pivotroot(&user_nd, &new_nd); error = 0; - path_put(&root_parent.path); - path_put(&parent_nd.path); + path_put(&root_parent); + path_put(&parent_path); out2: mutex_unlock(&old_nd.path.dentry->d_inode->i_mutex); up_write(&namespace_sem); |