diff options
| -rw-r--r-- | fs/namespace.c | 30 | ||||
| -rw-r--r-- | fs/proc/base.c | 62 | ||||
| -rw-r--r-- | include/linux/namespace.h | 2 |
3 files changed, 78 insertions, 16 deletions
diff --git a/fs/namespace.c b/fs/namespace.c index 611f777..d1aca68 100644 --- a/fs/namespace.c +++ b/fs/namespace.c @@ -37,7 +37,9 @@ static inline int sysfs_init(void) #endif /* spinlock for vfsmount related operations, inplace of dcache_lock */ - __cacheline_aligned_in_smp DEFINE_SPINLOCK(vfsmount_lock); +__cacheline_aligned_in_smp DEFINE_SPINLOCK(vfsmount_lock); + +static int event; static struct list_head *mount_hashtable; static int hash_mask __read_mostly, hash_bits __read_mostly; @@ -111,6 +113,22 @@ static inline int check_mnt(struct vfsmount *mnt) return mnt->mnt_namespace == current->namespace; } +static void touch_namespace(struct namespace *ns) +{ + if (ns) { + ns->event = ++event; + wake_up_interruptible(&ns->poll); + } +} + +static void __touch_namespace(struct namespace *ns) +{ + if (ns && ns->event != event) { + ns->event = event; + wake_up_interruptible(&ns->poll); + } +} + static void detach_mnt(struct vfsmount *mnt, struct nameidata *old_nd) { old_nd->dentry = mnt->mnt_mountpoint; @@ -384,6 +402,7 @@ static void umount_tree(struct vfsmount *mnt) for (p = mnt; p; p = next_mnt(p, mnt)) { list_del(&p->mnt_list); list_add(&p->mnt_list, &kill); + __touch_namespace(p->mnt_namespace); p->mnt_namespace = NULL; } @@ -473,6 +492,7 @@ static int do_umount(struct vfsmount *mnt, int flags) down_write(¤t->namespace->sem); spin_lock(&vfsmount_lock); + event++; retval = -EBUSY; if (atomic_read(&mnt->mnt_count) == 2 || flags & MNT_DETACH) { @@ -634,6 +654,7 @@ static int graft_tree(struct vfsmount *mnt, struct nameidata *nd) list_splice(&head, current->namespace->list.prev); mntget(mnt); err = 0; + touch_namespace(current->namespace); } spin_unlock(&vfsmount_lock); out_unlock: @@ -771,6 +792,7 @@ static int do_move_mount(struct nameidata *nd, char *old_name) detach_mnt(old_nd.mnt, &parent_nd); attach_mnt(old_nd.mnt, nd); + touch_namespace(current->namespace); /* if the mount is moved, it should no longer be expire * automatically */ @@ -877,6 +899,7 @@ static void expire_mount(struct vfsmount *mnt, struct list_head *mounts) struct nameidata old_nd; /* delete from the namespace */ + touch_namespace(mnt->mnt_namespace); list_del_init(&mnt->mnt_list); mnt->mnt_namespace = NULL; detach_mnt(mnt, &old_nd); @@ -1114,6 +1137,8 @@ int copy_namespace(int flags, struct task_struct *tsk) atomic_set(&new_ns->count, 1); init_rwsem(&new_ns->sem); INIT_LIST_HEAD(&new_ns->list); + init_waitqueue_head(&new_ns->poll); + new_ns->event = 0; down_write(&tsk->namespace->sem); /* First pass: copy the tree topology */ @@ -1377,6 +1402,7 @@ asmlinkage long sys_pivot_root(const char __user *new_root, const char __user *p detach_mnt(user_nd.mnt, &root_parent); attach_mnt(user_nd.mnt, &old_nd); /* mount old root on put_old */ attach_mnt(new_nd.mnt, &root_parent); /* mount new_root on / */ + touch_namespace(current->namespace); spin_unlock(&vfsmount_lock); chroot_fs_refs(&user_nd, &new_nd); security_sb_post_pivotroot(&user_nd, &new_nd); @@ -1413,6 +1439,8 @@ static void __init init_mount_tree(void) atomic_set(&namespace->count, 1); INIT_LIST_HEAD(&namespace->list); init_rwsem(&namespace->sem); + init_waitqueue_head(&namespace->poll); + namespace->event = 0; list_add(&mnt->mnt_list, &namespace->list); namespace->root = mnt; mnt->mnt_namespace = namespace; diff --git a/fs/proc/base.c b/fs/proc/base.c index a170450..634355e 100644 --- a/fs/proc/base.c +++ b/fs/proc/base.c @@ -70,6 +70,7 @@ #include <linux/seccomp.h> #include <linux/cpuset.h> #include <linux/audit.h> +#include <linux/poll.h> #include "internal.h" /* @@ -660,26 +661,38 @@ static struct file_operations proc_smaps_operations = { #endif extern struct seq_operations mounts_op; +struct proc_mounts { + struct seq_file m; + int event; +}; + static int mounts_open(struct inode *inode, struct file *file) { struct task_struct *task = proc_task(inode); - int ret = seq_open(file, &mounts_op); + struct namespace *namespace; + struct proc_mounts *p; + int ret = -EINVAL; - if (!ret) { - struct seq_file *m = file->private_data; - struct namespace *namespace; - task_lock(task); - namespace = task->namespace; - if (namespace) - get_namespace(namespace); - task_unlock(task); - - if (namespace) - m->private = namespace; - else { - seq_release(inode, file); - ret = -EINVAL; + task_lock(task); + namespace = task->namespace; + if (namespace) + get_namespace(namespace); + task_unlock(task); + + if (namespace) { + ret = -ENOMEM; + p = kmalloc(sizeof(struct proc_mounts), GFP_KERNEL); + if (p) { + file->private_data = &p->m; + ret = seq_open(file, &mounts_op); + if (!ret) { + p->m.private = namespace; + p->event = namespace->event; + return 0; + } + kfree(p); } + put_namespace(namespace); } return ret; } @@ -692,11 +705,30 @@ static int mounts_release(struct inode *inode, struct file *file) return seq_release(inode, file); } +static unsigned mounts_poll(struct file *file, poll_table *wait) +{ + struct proc_mounts *p = file->private_data; + struct namespace *ns = p->m.private; + unsigned res = 0; + + poll_wait(file, &ns->poll, wait); + + spin_lock(&vfsmount_lock); + if (p->event != ns->event) { + p->event = ns->event; + res = POLLERR; + } + spin_unlock(&vfsmount_lock); + + return res; +} + static struct file_operations proc_mounts_operations = { .open = mounts_open, .read = seq_read, .llseek = seq_lseek, .release = mounts_release, + .poll = mounts_poll, }; #define PROC_BLOCK_SIZE (3*1024) /* 4K page size but our output routines use some slack for overruns */ diff --git a/include/linux/namespace.h b/include/linux/namespace.h index 0e5a86f..6f0f25d 100644 --- a/include/linux/namespace.h +++ b/include/linux/namespace.h @@ -10,6 +10,8 @@ struct namespace { struct vfsmount * root; struct list_head list; struct rw_semaphore sem; + wait_queue_head_t poll; + int event; }; extern int copy_namespace(int, struct task_struct *); |
