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98f842e675
Assign a unique proc inode to each namespace, and use that inode number to ensure we only allocate at most one proc inode for every namespace in proc. A single proc inode per namespace allows userspace to test to see if two processes are in the same namespace. This has been a long requested feature and only blocked because a naive implementation would put the id in a global space and would ultimately require having a namespace for the names of namespaces, making migration and certain virtualization tricks impossible. We still don't have per superblock inode numbers for proc, which appears necessary for application unaware checkpoint/restart and migrations (if the application is using namespace file descriptors) but that is now allowd by the design if it becomes important. I have preallocated the ipc and uts initial proc inode numbers so their structures can be statically initialized. Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
89 lines
2.3 KiB
C
89 lines
2.3 KiB
C
#include <linux/mount.h>
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#include <linux/seq_file.h>
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#include <linux/poll.h>
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struct mnt_namespace {
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atomic_t count;
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unsigned int proc_inum;
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struct mount * root;
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struct list_head list;
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struct user_namespace *user_ns;
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u64 seq; /* Sequence number to prevent loops */
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wait_queue_head_t poll;
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int event;
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};
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struct mnt_pcp {
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int mnt_count;
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int mnt_writers;
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};
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struct mount {
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struct list_head mnt_hash;
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struct mount *mnt_parent;
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struct dentry *mnt_mountpoint;
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struct vfsmount mnt;
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#ifdef CONFIG_SMP
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struct mnt_pcp __percpu *mnt_pcp;
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#else
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int mnt_count;
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int mnt_writers;
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#endif
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struct list_head mnt_mounts; /* list of children, anchored here */
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struct list_head mnt_child; /* and going through their mnt_child */
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struct list_head mnt_instance; /* mount instance on sb->s_mounts */
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const char *mnt_devname; /* Name of device e.g. /dev/dsk/hda1 */
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struct list_head mnt_list;
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struct list_head mnt_expire; /* link in fs-specific expiry list */
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struct list_head mnt_share; /* circular list of shared mounts */
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struct list_head mnt_slave_list;/* list of slave mounts */
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struct list_head mnt_slave; /* slave list entry */
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struct mount *mnt_master; /* slave is on master->mnt_slave_list */
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struct mnt_namespace *mnt_ns; /* containing namespace */
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#ifdef CONFIG_FSNOTIFY
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struct hlist_head mnt_fsnotify_marks;
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__u32 mnt_fsnotify_mask;
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#endif
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int mnt_id; /* mount identifier */
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int mnt_group_id; /* peer group identifier */
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int mnt_expiry_mark; /* true if marked for expiry */
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int mnt_pinned;
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int mnt_ghosts;
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};
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#define MNT_NS_INTERNAL ERR_PTR(-EINVAL) /* distinct from any mnt_namespace */
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static inline struct mount *real_mount(struct vfsmount *mnt)
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{
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return container_of(mnt, struct mount, mnt);
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}
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static inline int mnt_has_parent(struct mount *mnt)
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{
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return mnt != mnt->mnt_parent;
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}
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static inline int is_mounted(struct vfsmount *mnt)
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{
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/* neither detached nor internal? */
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return !IS_ERR_OR_NULL(real_mount(mnt));
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}
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extern struct mount *__lookup_mnt(struct vfsmount *, struct dentry *, int);
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static inline void get_mnt_ns(struct mnt_namespace *ns)
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{
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atomic_inc(&ns->count);
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}
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struct proc_mounts {
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struct seq_file m;
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struct mnt_namespace *ns;
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struct path root;
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int (*show)(struct seq_file *, struct vfsmount *);
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};
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#define proc_mounts(p) (container_of((p), struct proc_mounts, m))
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extern const struct seq_operations mounts_op;
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