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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
This commit is contained in:
Linus Torvalds 2008-03-28 15:23:01 -07:00
parent d478376cb0 6758f953d0
commit af8be4e4b3
8 changed files with 71 additions and 146 deletions
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1
fs/afs/internal.h
View File

@ -573,7 +573,6 @@ extern const struct file_operations afs_mntpt_file_operations;
extern int afs_mntpt_check_symlink(struct afs_vnode *, struct key *);
extern void afs_mntpt_kill_timer(void);
extern void afs_umount_begin(struct vfsmount *, int);
/*
* proc.c

8
fs/afs/mntpt.c
View File

@ -283,11 +283,3 @@ void afs_mntpt_kill_timer(void)
cancel_delayed_work(&afs_mntpt_expiry_timer);
flush_scheduled_work();
}
/*
* begin unmount by attempting to remove all automounted mountpoints we added
*/
void afs_umount_begin(struct vfsmount *vfsmnt, int flags)
{
shrink_submounts(vfsmnt, &afs_vfsmounts);
}

1
fs/afs/super.c
View File

@ -50,7 +50,6 @@ static const struct super_operations afs_super_ops = {
.write_inode = afs_write_inode,
.destroy_inode = afs_destroy_inode,
.clear_inode = afs_clear_inode,
.umount_begin = afs_umount_begin,
.put_super = afs_put_super,
.show_options = generic_show_options,
};

1
fs/cifs/cifs_dfs_ref.c
View File

@ -33,7 +33,6 @@ void dfs_shrink_umount_helper(struct vfsmount *vfsmnt)
{
mark_mounts_for_expiry(&cifs_dfs_automount_list);
mark_mounts_for_expiry(&cifs_dfs_automount_list);
shrink_submounts(vfsmnt, &cifs_dfs_automount_list);
}
/**

200
fs/namespace.c
View File

@ -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);

2
fs/nfs/super.c
View File

@ -589,8 +589,6 @@ static void nfs_umount_begin(struct vfsmount *vfsmnt, int flags)
struct nfs_server *server = NFS_SB(vfsmnt->mnt_sb);
struct rpc_clnt *rpc;
shrink_submounts(vfsmnt, &nfs_automount_list);
if (!(flags & MNT_FORCE))
return;
/* -EIO all pending I/O */

2
fs/pnode.c
View File

@ -225,7 +225,7 @@ out:
*/
static inline int do_refcount_check(struct vfsmount *mnt, int count)
{
int mycount = atomic_read(&mnt->mnt_count);
int mycount = atomic_read(&mnt->mnt_count) - mnt->mnt_ghosts;
return (mycount > count);
}

2
include/linux/mount.h
View File

@ -61,6 +61,7 @@ struct vfsmount {
atomic_t mnt_count;
int mnt_expiry_mark; /* true if marked for expiry */
int mnt_pinned;
int mnt_ghosts;
};
static inline struct vfsmount *mntget(struct vfsmount *mnt)
@ -98,7 +99,6 @@ extern int do_add_mount(struct vfsmount *newmnt, struct nameidata *nd,
int mnt_flags, struct list_head *fslist);
extern void mark_mounts_for_expiry(struct list_head *mounts);
extern void shrink_submounts(struct vfsmount *mountpoint, struct list_head *mounts);
extern spinlock_t vfsmount_lock;
extern dev_t name_to_dev_t(char *name);