mirror of
https://github.com/edk2-porting/linux-next.git
synced 2024-12-25 05:34:00 +08:00
80b5dce8c5
The new function detach_mounts comes in two pieces. The first piece
is a static inline test of d_mounpoint that returns immediately
without taking any locks if d_mounpoint is not set. In the common
case when mountpoints are absent this allows the vfs to continue
running with it's same cacheline foot print.
The second piece of detach_mounts __detach_mounts actually does the
work and it assumes that a mountpoint is present so it is slow and
takes namespace_sem for write, and then locks the mount hash (aka
mount_lock) after a struct mountpoint has been found.
With those two locks held each entry on the list of mounts on a
mountpoint is selected and lazily unmounted until all of the mount
have been lazily unmounted.
v7: Wrote a proper change description and removed the changelog
documenting deleted wrong turns.
Signed-off-by: Eric W. Biederman <ebiederman@twitter.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
138 lines
3.4 KiB
C
138 lines
3.4 KiB
C
#include <linux/mount.h>
|
|
#include <linux/seq_file.h>
|
|
#include <linux/poll.h>
|
|
|
|
struct mnt_namespace {
|
|
atomic_t count;
|
|
unsigned int proc_inum;
|
|
struct mount * root;
|
|
struct list_head list;
|
|
struct user_namespace *user_ns;
|
|
u64 seq; /* Sequence number to prevent loops */
|
|
wait_queue_head_t poll;
|
|
u64 event;
|
|
};
|
|
|
|
struct mnt_pcp {
|
|
int mnt_count;
|
|
int mnt_writers;
|
|
};
|
|
|
|
struct mountpoint {
|
|
struct hlist_node m_hash;
|
|
struct dentry *m_dentry;
|
|
struct hlist_head m_list;
|
|
int m_count;
|
|
};
|
|
|
|
struct mount {
|
|
struct hlist_node mnt_hash;
|
|
struct mount *mnt_parent;
|
|
struct dentry *mnt_mountpoint;
|
|
struct vfsmount mnt;
|
|
union {
|
|
struct rcu_head mnt_rcu;
|
|
struct llist_node mnt_llist;
|
|
};
|
|
#ifdef CONFIG_SMP
|
|
struct mnt_pcp __percpu *mnt_pcp;
|
|
#else
|
|
int mnt_count;
|
|
int mnt_writers;
|
|
#endif
|
|
struct list_head mnt_mounts; /* list of children, anchored here */
|
|
struct list_head mnt_child; /* and going through their mnt_child */
|
|
struct list_head mnt_instance; /* mount instance on sb->s_mounts */
|
|
const char *mnt_devname; /* Name of device e.g. /dev/dsk/hda1 */
|
|
struct list_head mnt_list;
|
|
struct list_head mnt_expire; /* link in fs-specific expiry list */
|
|
struct list_head mnt_share; /* circular list of shared mounts */
|
|
struct list_head mnt_slave_list;/* list of slave mounts */
|
|
struct list_head mnt_slave; /* slave list entry */
|
|
struct mount *mnt_master; /* slave is on master->mnt_slave_list */
|
|
struct mnt_namespace *mnt_ns; /* containing namespace */
|
|
struct mountpoint *mnt_mp; /* where is it mounted */
|
|
struct hlist_node mnt_mp_list; /* list mounts with the same mountpoint */
|
|
#ifdef CONFIG_FSNOTIFY
|
|
struct hlist_head mnt_fsnotify_marks;
|
|
__u32 mnt_fsnotify_mask;
|
|
#endif
|
|
int mnt_id; /* mount identifier */
|
|
int mnt_group_id; /* peer group identifier */
|
|
int mnt_expiry_mark; /* true if marked for expiry */
|
|
struct hlist_head mnt_pins;
|
|
struct path mnt_ex_mountpoint;
|
|
};
|
|
|
|
#define MNT_NS_INTERNAL ERR_PTR(-EINVAL) /* distinct from any mnt_namespace */
|
|
|
|
static inline struct mount *real_mount(struct vfsmount *mnt)
|
|
{
|
|
return container_of(mnt, struct mount, mnt);
|
|
}
|
|
|
|
static inline int mnt_has_parent(struct mount *mnt)
|
|
{
|
|
return mnt != mnt->mnt_parent;
|
|
}
|
|
|
|
static inline int is_mounted(struct vfsmount *mnt)
|
|
{
|
|
/* neither detached nor internal? */
|
|
return !IS_ERR_OR_NULL(real_mount(mnt)->mnt_ns);
|
|
}
|
|
|
|
extern struct mount *__lookup_mnt(struct vfsmount *, struct dentry *);
|
|
extern struct mount *__lookup_mnt_last(struct vfsmount *, struct dentry *);
|
|
|
|
extern bool legitimize_mnt(struct vfsmount *, unsigned);
|
|
|
|
extern void __detach_mounts(struct dentry *dentry);
|
|
|
|
static inline void detach_mounts(struct dentry *dentry)
|
|
{
|
|
if (!d_mountpoint(dentry))
|
|
return;
|
|
__detach_mounts(dentry);
|
|
}
|
|
|
|
static inline void get_mnt_ns(struct mnt_namespace *ns)
|
|
{
|
|
atomic_inc(&ns->count);
|
|
}
|
|
|
|
extern seqlock_t mount_lock;
|
|
|
|
static inline void lock_mount_hash(void)
|
|
{
|
|
write_seqlock(&mount_lock);
|
|
}
|
|
|
|
static inline void unlock_mount_hash(void)
|
|
{
|
|
write_sequnlock(&mount_lock);
|
|
}
|
|
|
|
struct proc_mounts {
|
|
struct seq_file m;
|
|
struct mnt_namespace *ns;
|
|
struct path root;
|
|
int (*show)(struct seq_file *, struct vfsmount *);
|
|
void *cached_mount;
|
|
u64 cached_event;
|
|
loff_t cached_index;
|
|
};
|
|
|
|
#define proc_mounts(p) (container_of((p), struct proc_mounts, m))
|
|
|
|
extern const struct seq_operations mounts_op;
|
|
|
|
extern bool __is_local_mountpoint(struct dentry *dentry);
|
|
static inline bool is_local_mountpoint(struct dentry *dentry)
|
|
{
|
|
if (!d_mountpoint(dentry))
|
|
return false;
|
|
|
|
return __is_local_mountpoint(dentry);
|
|
}
|