}
/*
- * Most r/o checks on a fs are for operations that take
- * discrete amounts of time, like a write() or unlink().
- * We must keep track of when those operations start
- * (for permission checks) and when they end, so that
- * we can determine when writes are able to occur to
- * a filesystem.
+ * Most r/o & frozen checks on a fs are for operations that take discrete
+ * amounts of time, like a write() or unlink(). We must keep track of when
+ * those operations start (for permission checks) and when they end, so that we
+ * can determine when writes are able to occur to a filesystem.
*/
/**
- * mnt_want_write - get write access to a mount
+ * __mnt_want_write - get write access to a mount without freeze protection
* @m: the mount on which to take a write
*
- * This tells the low-level filesystem that a write is
- * about to be performed to it, and makes sure that
- * writes are allowed before returning success. When
- * the write operation is finished, mnt_drop_write()
- * must be called. This is effectively a refcount.
+ * This tells the low-level filesystem that a write is about to be performed to
+ * it, and makes sure that writes are allowed (mnt it read-write) before
+ * returning success. This operation does not protect against filesystem being
+ * frozen. When the write operation is finished, __mnt_drop_write() must be
+ * called. This is effectively a refcount.
*/
-int mnt_want_write(struct vfsmount *m)
+int __mnt_want_write(struct vfsmount *m)
{
struct mount *mnt = real_mount(m);
int ret = 0;
ret = -EROFS;
}
preempt_enable();
+
+ return ret;
+}
+
+/**
+ * mnt_want_write - get write access to a mount
+ * @m: the mount on which to take a write
+ *
+ * This tells the low-level filesystem that a write is about to be performed to
+ * it, and makes sure that writes are allowed (mount is read-write, filesystem
+ * is not frozen) before returning success. When the write operation is
+ * finished, mnt_drop_write() must be called. This is effectively a refcount.
+ */
+int mnt_want_write(struct vfsmount *m)
+{
+ int ret;
+
+ sb_start_write(m->mnt_sb);
+ ret = __mnt_want_write(m);
+ if (ret)
+ sb_end_write(m->mnt_sb);
return ret;
}
EXPORT_SYMBOL_GPL(mnt_want_write);
EXPORT_SYMBOL_GPL(mnt_clone_write);
/**
- * mnt_want_write_file - get write access to a file's mount
+ * __mnt_want_write_file - get write access to a file's mount
* @file: the file who's mount on which to take a write
*
- * This is like mnt_want_write, but it takes a file and can
+ * This is like __mnt_want_write, but it takes a file and can
* do some optimisations if the file is open for write already
*/
-int mnt_want_write_file(struct file *file)
+int __mnt_want_write_file(struct file *file)
{
struct inode *inode = file->f_dentry->d_inode;
+
if (!(file->f_mode & FMODE_WRITE) || special_file(inode->i_mode))
- return mnt_want_write(file->f_path.mnt);
+ return __mnt_want_write(file->f_path.mnt);
else
return mnt_clone_write(file->f_path.mnt);
}
+
+/**
+ * mnt_want_write_file - get write access to a file's mount
+ * @file: the file who's mount on which to take a write
+ *
+ * This is like mnt_want_write, but it takes a file and can
+ * do some optimisations if the file is open for write already
+ */
+int mnt_want_write_file(struct file *file)
+{
+ int ret;
+
+ sb_start_write(file->f_path.mnt->mnt_sb);
+ ret = __mnt_want_write_file(file);
+ if (ret)
+ sb_end_write(file->f_path.mnt->mnt_sb);
+ return ret;
+}
EXPORT_SYMBOL_GPL(mnt_want_write_file);
/**
- * mnt_drop_write - give up write access to a mount
+ * __mnt_drop_write - give up write access to a mount
* @mnt: the mount on which to give up write access
*
* Tells the low-level filesystem that we are done
* performing writes to it. Must be matched with
- * mnt_want_write() call above.
+ * __mnt_want_write() call above.
*/
-void mnt_drop_write(struct vfsmount *mnt)
+void __mnt_drop_write(struct vfsmount *mnt)
{
preempt_disable();
mnt_dec_writers(real_mount(mnt));
preempt_enable();
}
+
+/**
+ * mnt_drop_write - give up write access to a mount
+ * @mnt: the mount on which to give up write access
+ *
+ * Tells the low-level filesystem that we are done performing writes to it and
+ * also allows filesystem to be frozen again. Must be matched with
+ * mnt_want_write() call above.
+ */
+void mnt_drop_write(struct vfsmount *mnt)
+{
+ __mnt_drop_write(mnt);
+ sb_end_write(mnt->mnt_sb);
+}
EXPORT_SYMBOL_GPL(mnt_drop_write);
+void __mnt_drop_write_file(struct file *file)
+{
+ __mnt_drop_write(file->f_path.mnt);
+}
+
void mnt_drop_write_file(struct file *file)
{
mnt_drop_write(file->f_path.mnt);
}
/*
- * lookup_mnt increments the ref count before returning
- * the vfsmount struct.
+ * lookup_mnt - Return the first child mount mounted at path
+ *
+ * "First" means first mounted chronologically. If you create the
+ * following mounts:
+ *
+ * mount /dev/sda1 /mnt
+ * mount /dev/sda2 /mnt
+ * mount /dev/sda3 /mnt
+ *
+ * Then lookup_mnt() on the base /mnt dentry in the root mount will
+ * return successively the root dentry and vfsmount of /dev/sda1, then
+ * /dev/sda2, then /dev/sda3, then NULL.
+ *
+ * lookup_mnt takes a reference to the found vfsmount.
*/
struct vfsmount *lookup_mnt(struct path *path)
{
list_add_tail(&mnt->mnt_child, &real_mount(path->mnt)->mnt_mounts);
}
-static inline void __mnt_make_longterm(struct mount *mnt)
-{
-#ifdef CONFIG_SMP
- atomic_inc(&mnt->mnt_longterm);
-#endif
-}
-
-/* needs vfsmount lock for write */
-static inline void __mnt_make_shortterm(struct mount *mnt)
-{
-#ifdef CONFIG_SMP
- atomic_dec(&mnt->mnt_longterm);
-#endif
-}
-
/*
* vfsmount lock must be held for write
*/
BUG_ON(parent == mnt);
list_add_tail(&head, &mnt->mnt_list);
- list_for_each_entry(m, &head, mnt_list) {
+ list_for_each_entry(m, &head, mnt_list)
m->mnt_ns = n;
- __mnt_make_longterm(m);
- }
list_splice(&head, n->list.prev);
int flag)
{
struct super_block *sb = old->mnt.mnt_sb;
- struct mount *mnt = alloc_vfsmnt(old->mnt_devname);
+ struct mount *mnt;
+ int err;
- 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 = alloc_vfsmnt(old->mnt_devname);
+ if (!mnt)
+ return ERR_PTR(-ENOMEM);
- mnt->mnt.mnt_flags = old->mnt.mnt_flags & ~MNT_WRITE_HOLD;
- atomic_inc(&sb->s_active);
- mnt->mnt.mnt_sb = sb;
- mnt->mnt.mnt_root = dget(root);
- mnt->mnt_mountpoint = mnt->mnt.mnt_root;
- mnt->mnt_parent = mnt;
- br_write_lock(&vfsmount_lock);
- list_add_tail(&mnt->mnt_instance, &sb->s_mounts);
- br_write_unlock(&vfsmount_lock);
+ 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_SLAVE) {
- list_add(&mnt->mnt_slave, &old->mnt_slave_list);
- mnt->mnt_master = old;
- CLEAR_MNT_SHARED(mnt);
- } else if (!(flag & CL_PRIVATE)) {
- if ((flag & CL_MAKE_SHARED) || IS_MNT_SHARED(old))
- list_add(&mnt->mnt_share, &old->mnt_share);
- if (IS_MNT_SLAVE(old))
- list_add(&mnt->mnt_slave, &old->mnt_slave);
- mnt->mnt_master = old->mnt_master;
- }
- if (flag & CL_MAKE_SHARED)
- set_mnt_shared(mnt);
-
- /* stick the duplicate mount on the same expiry list
- * as the original if that was on one */
- if (flag & CL_EXPIRE) {
- if (!list_empty(&old->mnt_expire))
- list_add(&mnt->mnt_expire, &old->mnt_expire);
- }
+ if ((flag & CL_MAKE_SHARED) && !mnt->mnt_group_id) {
+ err = mnt_alloc_group_id(mnt);
+ if (err)
+ goto out_free;
+ }
+
+ mnt->mnt.mnt_flags = old->mnt.mnt_flags & ~MNT_WRITE_HOLD;
+ atomic_inc(&sb->s_active);
+ mnt->mnt.mnt_sb = sb;
+ mnt->mnt.mnt_root = dget(root);
+ mnt->mnt_mountpoint = mnt->mnt.mnt_root;
+ mnt->mnt_parent = mnt;
+ br_write_lock(&vfsmount_lock);
+ list_add_tail(&mnt->mnt_instance, &sb->s_mounts);
+ br_write_unlock(&vfsmount_lock);
+
+ if (flag & CL_SLAVE) {
+ list_add(&mnt->mnt_slave, &old->mnt_slave_list);
+ mnt->mnt_master = old;
+ CLEAR_MNT_SHARED(mnt);
+ } else if (!(flag & CL_PRIVATE)) {
+ if ((flag & CL_MAKE_SHARED) || IS_MNT_SHARED(old))
+ list_add(&mnt->mnt_share, &old->mnt_share);
+ if (IS_MNT_SLAVE(old))
+ list_add(&mnt->mnt_slave, &old->mnt_slave);
+ mnt->mnt_master = old->mnt_master;
+ }
+ if (flag & CL_MAKE_SHARED)
+ set_mnt_shared(mnt);
+
+ /* stick the duplicate mount on the same expiry list
+ * as the original if that was on one */
+ if (flag & CL_EXPIRE) {
+ if (!list_empty(&old->mnt_expire))
+ list_add(&mnt->mnt_expire, &old->mnt_expire);
}
+
return mnt;
out_free:
free_vfsmnt(mnt);
- return NULL;
+ return ERR_PTR(err);
}
static inline void mntfree(struct mount *mnt)
put_again:
#ifdef CONFIG_SMP
br_read_lock(&vfsmount_lock);
- if (likely(atomic_read(&mnt->mnt_longterm))) {
+ if (likely(mnt->mnt_ns)) {
+ /* shouldn't be the last one */
mnt_add_count(mnt, -1);
br_read_unlock(&vfsmount_lock);
return;
/* iterator; we want it to have access to namespace_sem, thus here... */
static void *m_start(struct seq_file *m, loff_t *pos)
{
- struct proc_mounts *p = container_of(m, struct proc_mounts, m);
+ struct proc_mounts *p = proc_mounts(m);
down_read(&namespace_sem);
return seq_list_start(&p->ns->list, *pos);
static void *m_next(struct seq_file *m, void *v, loff_t *pos)
{
- struct proc_mounts *p = container_of(m, struct proc_mounts, m);
+ struct proc_mounts *p = proc_mounts(m);
return seq_list_next(v, &p->ns->list, pos);
}
static int m_show(struct seq_file *m, void *v)
{
- struct proc_mounts *p = container_of(m, struct proc_mounts, m);
+ struct proc_mounts *p = proc_mounts(m);
struct mount *r = list_entry(v, struct mount, mnt_list);
return p->show(m, &r->mnt);
}
list_del_init(&p->mnt_expire);
list_del_init(&p->mnt_list);
__touch_mnt_namespace(p->mnt_ns);
- if (p->mnt_ns)
- __mnt_make_shortterm(p);
p->mnt_ns = NULL;
list_del_init(&p->mnt_child);
if (mnt_has_parent(p)) {
struct path path;
if (!(flag & CL_COPY_ALL) && IS_MNT_UNBINDABLE(mnt))
- return NULL;
+ return ERR_PTR(-EINVAL);
res = q = clone_mnt(mnt, dentry, flag);
- if (!q)
- goto Enomem;
+ if (IS_ERR(q))
+ return q;
+
q->mnt_mountpoint = mnt->mnt_mountpoint;
p = mnt;
path.mnt = &q->mnt;
path.dentry = p->mnt_mountpoint;
q = clone_mnt(p, p->mnt.mnt_root, flag);
- if (!q)
- goto Enomem;
+ if (IS_ERR(q))
+ goto out;
br_write_lock(&vfsmount_lock);
list_add_tail(&q->mnt_list, &res->mnt_list);
attach_mnt(q, &path);
}
}
return res;
-Enomem:
+out:
if (res) {
LIST_HEAD(umount_list);
br_write_lock(&vfsmount_lock);
br_write_unlock(&vfsmount_lock);
release_mounts(&umount_list);
}
- return NULL;
+ return q;
}
+/* Caller should check returned pointer for errors */
+
struct vfsmount *collect_mounts(struct path *path)
{
struct mount *tree;
tree = copy_tree(real_mount(path->mnt), path->dentry,
CL_COPY_ALL | CL_PRIVATE);
up_write(&namespace_sem);
- return tree ? &tree->mnt : NULL;
+ if (IS_ERR(tree))
+ return NULL;
+ return &tree->mnt;
}
void drop_collected_mounts(struct vfsmount *mnt)
if (!check_mnt(real_mount(path->mnt)) || !check_mnt(old))
goto out2;
- err = -ENOMEM;
if (recurse)
mnt = copy_tree(old, old_path.dentry, 0);
else
mnt = clone_mnt(old, old_path.dentry, 0);
- if (!mnt)
- goto out2;
+ if (IS_ERR(mnt)) {
+ err = PTR_ERR(mnt);
+ goto out;
+ }
err = graft_tree(mnt, path);
if (err) {
return new_ns;
}
-void mnt_make_longterm(struct vfsmount *mnt)
-{
- __mnt_make_longterm(real_mount(mnt));
-}
-
-void mnt_make_shortterm(struct vfsmount *m)
-{
-#ifdef CONFIG_SMP
- struct mount *mnt = real_mount(m);
- if (atomic_add_unless(&mnt->mnt_longterm, -1, 1))
- return;
- br_write_lock(&vfsmount_lock);
- atomic_dec(&mnt->mnt_longterm);
- br_write_unlock(&vfsmount_lock);
-#endif
-}
-
/*
* Allocate a new namespace structure and populate it with contents
* copied from the namespace of the passed in task structure.
down_write(&namespace_sem);
/* First pass: copy the tree topology */
new = copy_tree(old, old->mnt.mnt_root, CL_COPY_ALL | CL_EXPIRE);
- if (!new) {
+ if (IS_ERR(new)) {
up_write(&namespace_sem);
kfree(new_ns);
- return ERR_PTR(-ENOMEM);
+ return ERR_CAST(new);
}
new_ns->root = new;
br_write_lock(&vfsmount_lock);
q = new;
while (p) {
q->mnt_ns = new_ns;
- __mnt_make_longterm(q);
if (fs) {
if (&p->mnt == fs->root.mnt) {
fs->root.mnt = mntget(&q->mnt);
- __mnt_make_longterm(q);
- mnt_make_shortterm(&p->mnt);
rootmnt = &p->mnt;
}
if (&p->mnt == fs->pwd.mnt) {
fs->pwd.mnt = mntget(&q->mnt);
- __mnt_make_longterm(q);
- mnt_make_shortterm(&p->mnt);
pwdmnt = &p->mnt;
}
}
if (!IS_ERR(new_ns)) {
struct mount *mnt = real_mount(m);
mnt->mnt_ns = new_ns;
- __mnt_make_longterm(mnt);
new_ns->root = mnt;
list_add(&new_ns->list, &mnt->mnt_list);
} else {
* it is a longterm mount, don't release mnt until
* we unmount before file sys is unregistered
*/
- mnt_make_longterm(mnt);
+ real_mount(mnt)->mnt_ns = MNT_NS_INTERNAL;
}
return mnt;
}
{
/* release long term mount so mount point can be released */
if (!IS_ERR_OR_NULL(mnt)) {
- mnt_make_shortterm(mnt);
+ br_write_lock(&vfsmount_lock);
+ real_mount(mnt)->mnt_ns = NULL;
+ br_write_unlock(&vfsmount_lock);
mntput(mnt);
}
}
git.openpandora.org / pandora-kernel.git / blobdiff